[PATCH] libata: use xfer_mask helpers in ata_dev_set_mode()

[deliverable/linux.git] / drivers / scsi / libata-core.c

/*
 *  libata-core.c - helper library for ATA
 *
 *  Maintained by:  Jeff Garzik <jgarzik@pobox.com>
 *                  Please ALWAYS copy linux-ide@vger.kernel.org
 *                  on emails.
 *
 *  Copyright 2003-2004 Red Hat, Inc.  All rights reserved.
 *  Copyright 2003-2004 Jeff Garzik
 *
 *
 *  This program is free software; you can redistribute it and/or modify
 *  it under the terms of the GNU General Public License as published by
 *  the Free Software Foundation; either version 2, or (at your option)
 *  any later version.
 *
 *  This program is distributed in the hope that it will be useful,
 *  but WITHOUT ANY WARRANTY; without even the implied warranty of
 *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 *  GNU General Public License for more details.
 *
 *  You should have received a copy of the GNU General Public License
 *  along with this program; see the file COPYING.  If not, write to
 *  the Free Software Foundation, 675 Mass Ave, Cambridge, MA 02139, USA.
 *
 *
 *  libata documentation is available via 'make {ps|pdf}docs',
 *  as Documentation/DocBook/libata.*
 *
 *  Hardware documentation available from http://www.t13.org/ and
 *  http://www.sata-io.org/
 *
 */

#include <linux/config.h>
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/pci.h>
#include <linux/init.h>
#include <linux/list.h>
#include <linux/mm.h>
#include <linux/highmem.h>
#include <linux/spinlock.h>
#include <linux/blkdev.h>
#include <linux/delay.h>
#include <linux/timer.h>
#include <linux/interrupt.h>
#include <linux/completion.h>
#include <linux/suspend.h>
#include <linux/workqueue.h>
#include <linux/jiffies.h>
#include <linux/scatterlist.h>
#include <scsi/scsi.h>
#include "scsi_priv.h"
#include <scsi/scsi_cmnd.h>
#include <scsi/scsi_host.h>
#include <linux/libata.h>
#include <asm/io.h>
#include <asm/semaphore.h>
#include <asm/byteorder.h>

#include "libata.h"

static unsigned int ata_dev_init_params(struct ata_port *ap,
                                        struct ata_device *dev);
static void ata_set_mode(struct ata_port *ap);
static void ata_dev_set_xfermode(struct ata_port *ap, struct ata_device *dev);
static unsigned int ata_get_mode_mask(const struct ata_port *ap, int shift);
static int fgb(u32 bitmap);
static int ata_choose_xfer_mode(const struct ata_port *ap,
                                u8 *xfer_mode_out,
                                unsigned int *xfer_shift_out);

static unsigned int ata_unique_id = 1;
static struct workqueue_struct *ata_wq;

int atapi_enabled = 0;
module_param(atapi_enabled, int, 0444);
MODULE_PARM_DESC(atapi_enabled, "Enable discovery of ATAPI devices (0=off, 1=on)");

int libata_fua = 0;
module_param_named(fua, libata_fua, int, 0444);
MODULE_PARM_DESC(fua, "FUA support (0=off, 1=on)");

MODULE_AUTHOR("Jeff Garzik");
MODULE_DESCRIPTION("Library module for ATA devices");
MODULE_LICENSE("GPL");
MODULE_VERSION(DRV_VERSION);


/**
 *      ata_tf_to_fis - Convert ATA taskfile to SATA FIS structure
 *      @tf: Taskfile to convert
 *      @fis: Buffer into which data will output
 *      @pmp: Port multiplier port
 *
 *      Converts a standard ATA taskfile to a Serial ATA
 *      FIS structure (Register - Host to Device).
 *
 *      LOCKING:
 *      Inherited from caller.
 */

void ata_tf_to_fis(const struct ata_taskfile *tf, u8 *fis, u8 pmp)
{
        fis[0] = 0x27;  /* Register - Host to Device FIS */
        fis[1] = (pmp & 0xf) | (1 << 7); /* Port multiplier number,
                                            bit 7 indicates Command FIS */
        fis[2] = tf->command;
        fis[3] = tf->feature;

        fis[4] = tf->lbal;
        fis[5] = tf->lbam;
        fis[6] = tf->lbah;
        fis[7] = tf->device;

        fis[8] = tf->hob_lbal;
        fis[9] = tf->hob_lbam;
        fis[10] = tf->hob_lbah;
        fis[11] = tf->hob_feature;

        fis[12] = tf->nsect;
        fis[13] = tf->hob_nsect;
        fis[14] = 0;
        fis[15] = tf->ctl;

        fis[16] = 0;
        fis[17] = 0;
        fis[18] = 0;
        fis[19] = 0;
}

/**
 *      ata_tf_from_fis - Convert SATA FIS to ATA taskfile
 *      @fis: Buffer from which data will be input
 *      @tf: Taskfile to output
 *
 *      Converts a serial ATA FIS structure to a standard ATA taskfile.
 *
 *      LOCKING:
 *      Inherited from caller.
 */

void ata_tf_from_fis(const u8 *fis, struct ata_taskfile *tf)
{
        tf->command     = fis[2];       /* status */
        tf->feature     = fis[3];       /* error */

        tf->lbal        = fis[4];
        tf->lbam        = fis[5];
        tf->lbah        = fis[6];
        tf->device      = fis[7];

        tf->hob_lbal    = fis[8];
        tf->hob_lbam    = fis[9];
        tf->hob_lbah    = fis[10];

        tf->nsect       = fis[12];
        tf->hob_nsect   = fis[13];
}

static const u8 ata_rw_cmds[] = {
        /* pio multi */
        ATA_CMD_READ_MULTI,
        ATA_CMD_WRITE_MULTI,
        ATA_CMD_READ_MULTI_EXT,
        ATA_CMD_WRITE_MULTI_EXT,
        0,
        0,
        0,
        ATA_CMD_WRITE_MULTI_FUA_EXT,
        /* pio */
        ATA_CMD_PIO_READ,
        ATA_CMD_PIO_WRITE,
        ATA_CMD_PIO_READ_EXT,
        ATA_CMD_PIO_WRITE_EXT,
        0,
        0,
        0,
        0,
        /* dma */
        ATA_CMD_READ,
        ATA_CMD_WRITE,
        ATA_CMD_READ_EXT,
        ATA_CMD_WRITE_EXT,
        0,
        0,
        0,
        ATA_CMD_WRITE_FUA_EXT
};

/**
 *      ata_rwcmd_protocol - set taskfile r/w commands and protocol
 *      @qc: command to examine and configure
 *
 *      Examine the device configuration and tf->flags to calculate 
 *      the proper read/write commands and protocol to use.
 *
 *      LOCKING:
 *      caller.
 */
int ata_rwcmd_protocol(struct ata_queued_cmd *qc)
{
        struct ata_taskfile *tf = &qc->tf;
        struct ata_device *dev = qc->dev;
        u8 cmd;

        int index, fua, lba48, write;
 
        fua = (tf->flags & ATA_TFLAG_FUA) ? 4 : 0;
        lba48 = (tf->flags & ATA_TFLAG_LBA48) ? 2 : 0;
        write = (tf->flags & ATA_TFLAG_WRITE) ? 1 : 0;

        if (dev->flags & ATA_DFLAG_PIO) {
                tf->protocol = ATA_PROT_PIO;
                index = dev->multi_count ? 0 : 8;
        } else if (lba48 && (qc->ap->flags & ATA_FLAG_PIO_LBA48)) {
                /* Unable to use DMA due to host limitation */
                tf->protocol = ATA_PROT_PIO;
                index = dev->multi_count ? 0 : 8;
        } else {
                tf->protocol = ATA_PROT_DMA;
                index = 16;
        }

        cmd = ata_rw_cmds[index + fua + lba48 + write];
        if (cmd) {
                tf->command = cmd;
                return 0;
        }
        return -1;
}

/**
 *      ata_pack_xfermask - Pack pio, mwdma and udma masks into xfer_mask
 *      @pio_mask: pio_mask
 *      @mwdma_mask: mwdma_mask
 *      @udma_mask: udma_mask
 *
 *      Pack @pio_mask, @mwdma_mask and @udma_mask into a single
 *      unsigned int xfer_mask.
 *
 *      LOCKING:
 *      None.
 *
 *      RETURNS:
 *      Packed xfer_mask.
 */
static unsigned int ata_pack_xfermask(unsigned int pio_mask,
                                      unsigned int mwdma_mask,
                                      unsigned int udma_mask)
{
        return ((pio_mask << ATA_SHIFT_PIO) & ATA_MASK_PIO) |
                ((mwdma_mask << ATA_SHIFT_MWDMA) & ATA_MASK_MWDMA) |
                ((udma_mask << ATA_SHIFT_UDMA) & ATA_MASK_UDMA);
}

static const struct ata_xfer_ent {
        unsigned int shift, bits;
        u8 base;
} ata_xfer_tbl[] = {
        { ATA_SHIFT_PIO, ATA_BITS_PIO, XFER_PIO_0 },
        { ATA_SHIFT_MWDMA, ATA_BITS_MWDMA, XFER_MW_DMA_0 },
        { ATA_SHIFT_UDMA, ATA_BITS_UDMA, XFER_UDMA_0 },
        { -1, },
};

/**
 *      ata_xfer_mask2mode - Find matching XFER_* for the given xfer_mask
 *      @xfer_mask: xfer_mask of interest
 *
 *      Return matching XFER_* value for @xfer_mask.  Only the highest
 *      bit of @xfer_mask is considered.
 *
 *      LOCKING:
 *      None.
 *
 *      RETURNS:
 *      Matching XFER_* value, 0 if no match found.
 */
static u8 ata_xfer_mask2mode(unsigned int xfer_mask)
{
        int highbit = fls(xfer_mask) - 1;
        const struct ata_xfer_ent *ent;

        for (ent = ata_xfer_tbl; ent->shift >= 0; ent++)
                if (highbit >= ent->shift && highbit < ent->shift + ent->bits)
                        return ent->base + highbit - ent->shift;
        return 0;
}

/**
 *      ata_xfer_mode2mask - Find matching xfer_mask for XFER_*
 *      @xfer_mode: XFER_* of interest
 *
 *      Return matching xfer_mask for @xfer_mode.
 *
 *      LOCKING:
 *      None.
 *
 *      RETURNS:
 *      Matching xfer_mask, 0 if no match found.
 */
static unsigned int ata_xfer_mode2mask(u8 xfer_mode)
{
        const struct ata_xfer_ent *ent;

        for (ent = ata_xfer_tbl; ent->shift >= 0; ent++)
                if (xfer_mode >= ent->base && xfer_mode < ent->base + ent->bits)
                        return 1 << (ent->shift + xfer_mode - ent->base);
        return 0;
}

/**
 *      ata_xfer_mode2shift - Find matching xfer_shift for XFER_*
 *      @xfer_mode: XFER_* of interest
 *
 *      Return matching xfer_shift for @xfer_mode.
 *
 *      LOCKING:
 *      None.
 *
 *      RETURNS:
 *      Matching xfer_shift, -1 if no match found.
 */
static int ata_xfer_mode2shift(unsigned int xfer_mode)
{
        const struct ata_xfer_ent *ent;

        for (ent = ata_xfer_tbl; ent->shift >= 0; ent++)
                if (xfer_mode >= ent->base && xfer_mode < ent->base + ent->bits)
                        return ent->shift;
        return -1;
}

static const char * const xfer_mode_str[] = {
        "PIO0",
        "PIO1",
        "PIO2",
        "PIO3",
        "PIO4",
        "MWDMA0",
        "MWDMA1",
        "MWDMA2",
        "UDMA/16",
        "UDMA/25",
        "UDMA/33",
        "UDMA/44",
        "UDMA/66",
        "UDMA/100",
        "UDMA/133",
        "UDMA7",
};

/**
 *      ata_mode_string - convert xfer_mask to string
 *      @xfer_mask: mask of bits supported; only highest bit counts.
 *
 *      Determine string which represents the highest speed
 *      (highest bit in @modemask).
 *
 *      LOCKING:
 *      None.
 *
 *      RETURNS:
 *      Constant C string representing highest speed listed in
 *      @mode_mask, or the constant C string "<n/a>".
 */

static const char *ata_mode_string(unsigned int xfer_mask)
{
        int highbit;

        highbit = fls(xfer_mask) - 1;
        if (highbit >= 0 && highbit < ARRAY_SIZE(xfer_mode_str))
                return xfer_mode_str[highbit];
        return "<n/a>";
}

/**
 *      ata_pio_devchk - PATA device presence detection
 *      @ap: ATA channel to examine
 *      @device: Device to examine (starting at zero)
 *
 *      This technique was originally described in
 *      Hale Landis's ATADRVR (www.ata-atapi.com), and
 *      later found its way into the ATA/ATAPI spec.
 *
 *      Write a pattern to the ATA shadow registers,
 *      and if a device is present, it will respond by
 *      correctly storing and echoing back the
 *      ATA shadow register contents.
 *
 *      LOCKING:
 *      caller.
 */

static unsigned int ata_pio_devchk(struct ata_port *ap,
                                   unsigned int device)
{
        struct ata_ioports *ioaddr = &ap->ioaddr;
        u8 nsect, lbal;

        ap->ops->dev_select(ap, device);

        outb(0x55, ioaddr->nsect_addr);
        outb(0xaa, ioaddr->lbal_addr);

        outb(0xaa, ioaddr->nsect_addr);
        outb(0x55, ioaddr->lbal_addr);

        outb(0x55, ioaddr->nsect_addr);
        outb(0xaa, ioaddr->lbal_addr);

        nsect = inb(ioaddr->nsect_addr);
        lbal = inb(ioaddr->lbal_addr);

        if ((nsect == 0x55) && (lbal == 0xaa))
                return 1;       /* we found a device */

        return 0;               /* nothing found */
}

/**
 *      ata_mmio_devchk - PATA device presence detection
 *      @ap: ATA channel to examine
 *      @device: Device to examine (starting at zero)
 *
 *      This technique was originally described in
 *      Hale Landis's ATADRVR (www.ata-atapi.com), and
 *      later found its way into the ATA/ATAPI spec.
 *
 *      Write a pattern to the ATA shadow registers,
 *      and if a device is present, it will respond by
 *      correctly storing and echoing back the
 *      ATA shadow register contents.
 *
 *      LOCKING:
 *      caller.
 */

static unsigned int ata_mmio_devchk(struct ata_port *ap,
                                    unsigned int device)
{
        struct ata_ioports *ioaddr = &ap->ioaddr;
        u8 nsect, lbal;

        ap->ops->dev_select(ap, device);

        writeb(0x55, (void __iomem *) ioaddr->nsect_addr);
        writeb(0xaa, (void __iomem *) ioaddr->lbal_addr);

        writeb(0xaa, (void __iomem *) ioaddr->nsect_addr);
        writeb(0x55, (void __iomem *) ioaddr->lbal_addr);

        writeb(0x55, (void __iomem *) ioaddr->nsect_addr);
        writeb(0xaa, (void __iomem *) ioaddr->lbal_addr);

        nsect = readb((void __iomem *) ioaddr->nsect_addr);
        lbal = readb((void __iomem *) ioaddr->lbal_addr);

        if ((nsect == 0x55) && (lbal == 0xaa))
                return 1;       /* we found a device */

        return 0;               /* nothing found */
}

/**
 *      ata_devchk - PATA device presence detection
 *      @ap: ATA channel to examine
 *      @device: Device to examine (starting at zero)
 *
 *      Dispatch ATA device presence detection, depending
 *      on whether we are using PIO or MMIO to talk to the
 *      ATA shadow registers.
 *
 *      LOCKING:
 *      caller.
 */

static unsigned int ata_devchk(struct ata_port *ap,
                                    unsigned int device)
{
        if (ap->flags & ATA_FLAG_MMIO)
                return ata_mmio_devchk(ap, device);
        return ata_pio_devchk(ap, device);
}

/**
 *      ata_dev_classify - determine device type based on ATA-spec signature
 *      @tf: ATA taskfile register set for device to be identified
 *
 *      Determine from taskfile register contents whether a device is
 *      ATA or ATAPI, as per "Signature and persistence" section
 *      of ATA/PI spec (volume 1, sect 5.14).
 *
 *      LOCKING:
 *      None.
 *
 *      RETURNS:
 *      Device type, %ATA_DEV_ATA, %ATA_DEV_ATAPI, or %ATA_DEV_UNKNOWN
 *      the event of failure.
 */

unsigned int ata_dev_classify(const struct ata_taskfile *tf)
{
        /* Apple's open source Darwin code hints that some devices only
         * put a proper signature into the LBA mid/high registers,
         * So, we only check those.  It's sufficient for uniqueness.
         */

        if (((tf->lbam == 0) && (tf->lbah == 0)) ||
            ((tf->lbam == 0x3c) && (tf->lbah == 0xc3))) {
                DPRINTK("found ATA device by sig\n");
                return ATA_DEV_ATA;
        }

        if (((tf->lbam == 0x14) && (tf->lbah == 0xeb)) ||
            ((tf->lbam == 0x69) && (tf->lbah == 0x96))) {
                DPRINTK("found ATAPI device by sig\n");
                return ATA_DEV_ATAPI;
        }

        DPRINTK("unknown device\n");
        return ATA_DEV_UNKNOWN;
}

/**
 *      ata_dev_try_classify - Parse returned ATA device signature
 *      @ap: ATA channel to examine
 *      @device: Device to examine (starting at zero)
 *      @r_err: Value of error register on completion
 *
 *      After an event -- SRST, E.D.D., or SATA COMRESET -- occurs,
 *      an ATA/ATAPI-defined set of values is placed in the ATA
 *      shadow registers, indicating the results of device detection
 *      and diagnostics.
 *
 *      Select the ATA device, and read the values from the ATA shadow
 *      registers.  Then parse according to the Error register value,
 *      and the spec-defined values examined by ata_dev_classify().
 *
 *      LOCKING:
 *      caller.
 *
 *      RETURNS:
 *      Device type - %ATA_DEV_ATA, %ATA_DEV_ATAPI or %ATA_DEV_NONE.
 */

static unsigned int
ata_dev_try_classify(struct ata_port *ap, unsigned int device, u8 *r_err)
{
        struct ata_taskfile tf;
        unsigned int class;
        u8 err;

        ap->ops->dev_select(ap, device);

        memset(&tf, 0, sizeof(tf));

        ap->ops->tf_read(ap, &tf);
        err = tf.feature;
        if (r_err)
                *r_err = err;

        /* see if device passed diags */
        if (err == 1)
                /* do nothing */ ;
        else if ((device == 0) && (err == 0x81))
                /* do nothing */ ;
        else
                return ATA_DEV_NONE;

        /* determine if device is ATA or ATAPI */
        class = ata_dev_classify(&tf);

        if (class == ATA_DEV_UNKNOWN)
                return ATA_DEV_NONE;
        if ((class == ATA_DEV_ATA) && (ata_chk_status(ap) == 0))
                return ATA_DEV_NONE;
        return class;
}

/**
 *      ata_id_string - Convert IDENTIFY DEVICE page into string
 *      @id: IDENTIFY DEVICE results we will examine
 *      @s: string into which data is output
 *      @ofs: offset into identify device page
 *      @len: length of string to return. must be an even number.
 *
 *      The strings in the IDENTIFY DEVICE page are broken up into
 *      16-bit chunks.  Run through the string, and output each
 *      8-bit chunk linearly, regardless of platform.
 *
 *      LOCKING:
 *      caller.
 */

void ata_id_string(const u16 *id, unsigned char *s,
                   unsigned int ofs, unsigned int len)
{
        unsigned int c;

        while (len > 0) {
                c = id[ofs] >> 8;
                *s = c;
                s++;

                c = id[ofs] & 0xff;
                *s = c;
                s++;

                ofs++;
                len -= 2;
        }
}

/**
 *      ata_id_c_string - Convert IDENTIFY DEVICE page into C string
 *      @id: IDENTIFY DEVICE results we will examine
 *      @s: string into which data is output
 *      @ofs: offset into identify device page
 *      @len: length of string to return. must be an odd number.
 *
 *      This function is identical to ata_id_string except that it
 *      trims trailing spaces and terminates the resulting string with
 *      null.  @len must be actual maximum length (even number) + 1.
 *
 *      LOCKING:
 *      caller.
 */
void ata_id_c_string(const u16 *id, unsigned char *s,
                     unsigned int ofs, unsigned int len)
{
        unsigned char *p;

        WARN_ON(!(len & 1));

        ata_id_string(id, s, ofs, len - 1);

        p = s + strnlen(s, len - 1);
        while (p > s && p[-1] == ' ')
                p--;
        *p = '\0';
}

static u64 ata_id_n_sectors(const u16 *id)
{
        if (ata_id_has_lba(id)) {
                if (ata_id_has_lba48(id))
                        return ata_id_u64(id, 100);
                else
                        return ata_id_u32(id, 60);
        } else {
                if (ata_id_current_chs_valid(id))
                        return ata_id_u32(id, 57);
                else
                        return id[1] * id[3] * id[6];
        }
}

/**
 *      ata_noop_dev_select - Select device 0/1 on ATA bus
 *      @ap: ATA channel to manipulate
 *      @device: ATA device (numbered from zero) to select
 *
 *      This function performs no actual function.
 *
 *      May be used as the dev_select() entry in ata_port_operations.
 *
 *      LOCKING:
 *      caller.
 */
void ata_noop_dev_select (struct ata_port *ap, unsigned int device)
{
}


/**
 *      ata_std_dev_select - Select device 0/1 on ATA bus
 *      @ap: ATA channel to manipulate
 *      @device: ATA device (numbered from zero) to select
 *
 *      Use the method defined in the ATA specification to
 *      make either device 0, or device 1, active on the
 *      ATA channel.  Works with both PIO and MMIO.
 *
 *      May be used as the dev_select() entry in ata_port_operations.
 *
 *      LOCKING:
 *      caller.
 */

void ata_std_dev_select (struct ata_port *ap, unsigned int device)
{
        u8 tmp;

        if (device == 0)
                tmp = ATA_DEVICE_OBS;
        else
                tmp = ATA_DEVICE_OBS | ATA_DEV1;

        if (ap->flags & ATA_FLAG_MMIO) {
                writeb(tmp, (void __iomem *) ap->ioaddr.device_addr);
        } else {
                outb(tmp, ap->ioaddr.device_addr);
        }
        ata_pause(ap);          /* needed; also flushes, for mmio */
}

/**
 *      ata_dev_select - Select device 0/1 on ATA bus
 *      @ap: ATA channel to manipulate
 *      @device: ATA device (numbered from zero) to select
 *      @wait: non-zero to wait for Status register BSY bit to clear
 *      @can_sleep: non-zero if context allows sleeping
 *
 *      Use the method defined in the ATA specification to
 *      make either device 0, or device 1, active on the
 *      ATA channel.
 *
 *      This is a high-level version of ata_std_dev_select(),
 *      which additionally provides the services of inserting
 *      the proper pauses and status polling, where needed.
 *
 *      LOCKING:
 *      caller.
 */

void ata_dev_select(struct ata_port *ap, unsigned int device,
                           unsigned int wait, unsigned int can_sleep)
{
        VPRINTK("ENTER, ata%u: device %u, wait %u\n",
                ap->id, device, wait);

        if (wait)
                ata_wait_idle(ap);

        ap->ops->dev_select(ap, device);

        if (wait) {
                if (can_sleep && ap->device[device].class == ATA_DEV_ATAPI)
                        msleep(150);
                ata_wait_idle(ap);
        }
}

/**
 *      ata_dump_id - IDENTIFY DEVICE info debugging output
 *      @id: IDENTIFY DEVICE page to dump
 *
 *      Dump selected 16-bit words from the given IDENTIFY DEVICE
 *      page.
 *
 *      LOCKING:
 *      caller.
 */

static inline void ata_dump_id(const u16 *id)
{
        DPRINTK("49==0x%04x  "
                "53==0x%04x  "
                "63==0x%04x  "
                "64==0x%04x  "
                "75==0x%04x  \n",
                id[49],
                id[53],
                id[63],
                id[64],
                id[75]);
        DPRINTK("80==0x%04x  "
                "81==0x%04x  "
                "82==0x%04x  "
                "83==0x%04x  "
                "84==0x%04x  \n",
                id[80],
                id[81],
                id[82],
                id[83],
                id[84]);
        DPRINTK("88==0x%04x  "
                "93==0x%04x\n",
                id[88],
                id[93]);
}

/**
 *      ata_id_xfermask - Compute xfermask from the given IDENTIFY data
 *      @id: IDENTIFY data to compute xfer mask from
 *
 *      Compute the xfermask for this device. This is not as trivial
 *      as it seems if we must consider early devices correctly.
 *
 *      FIXME: pre IDE drive timing (do we care ?).
 *
 *      LOCKING:
 *      None.
 *
 *      RETURNS:
 *      Computed xfermask
 */
static unsigned int ata_id_xfermask(const u16 *id)
{
        unsigned int pio_mask, mwdma_mask, udma_mask;

        /* Usual case. Word 53 indicates word 64 is valid */
        if (id[ATA_ID_FIELD_VALID] & (1 << 1)) {
                pio_mask = id[ATA_ID_PIO_MODES] & 0x03;
                pio_mask <<= 3;
                pio_mask |= 0x7;
        } else {
                /* If word 64 isn't valid then Word 51 high byte holds
                 * the PIO timing number for the maximum. Turn it into
                 * a mask.
                 */
                pio_mask = (2 << (id[ATA_ID_OLD_PIO_MODES] & 0xFF)) - 1 ;

                /* But wait.. there's more. Design your standards by
                 * committee and you too can get a free iordy field to
                 * process. However its the speeds not the modes that
                 * are supported... Note drivers using the timing API
                 * will get this right anyway
                 */
        }

        mwdma_mask = id[ATA_ID_MWDMA_MODES] & 0x07;
        udma_mask = id[ATA_ID_UDMA_MODES] & 0xff;

        return ata_pack_xfermask(pio_mask, mwdma_mask, udma_mask);
}

/*
 *      Compute the PIO modes available for this device. This is not as
 *      trivial as it seems if we must consider early devices correctly.
 *
 *      FIXME: pre IDE drive timing (do we care ?). 
 */

static unsigned int ata_pio_modes(const struct ata_device *adev)
{
        u16 modes;

        /* Usual case. Word 53 indicates word 64 is valid */
        if (adev->id[ATA_ID_FIELD_VALID] & (1 << 1)) {
                modes = adev->id[ATA_ID_PIO_MODES] & 0x03;
                modes <<= 3;
                modes |= 0x7;
                return modes;
        }

        /* If word 64 isn't valid then Word 51 high byte holds the PIO timing
           number for the maximum. Turn it into a mask and return it */
        modes = (2 << ((adev->id[ATA_ID_OLD_PIO_MODES] >> 8) & 0xFF)) - 1 ;
        return modes;
        /* But wait.. there's more. Design your standards by committee and
           you too can get a free iordy field to process. However its the 
           speeds not the modes that are supported... Note drivers using the
           timing API will get this right anyway */
}

/**
 *      ata_port_queue_task - Queue port_task
 *      @ap: The ata_port to queue port_task for
 *
 *      Schedule @fn(@data) for execution after @delay jiffies using
 *      port_task.  There is one port_task per port and it's the
 *      user(low level driver)'s responsibility to make sure that only
 *      one task is active at any given time.
 *
 *      libata core layer takes care of synchronization between
 *      port_task and EH.  ata_port_queue_task() may be ignored for EH
 *      synchronization.
 *
 *      LOCKING:
 *      Inherited from caller.
 */
void ata_port_queue_task(struct ata_port *ap, void (*fn)(void *), void *data,
                         unsigned long delay)
{
        int rc;

        if (ap->flags & ATA_FLAG_FLUSH_PORT_TASK)
                return;

        PREPARE_WORK(&ap->port_task, fn, data);

        if (!delay)
                rc = queue_work(ata_wq, &ap->port_task);
        else
                rc = queue_delayed_work(ata_wq, &ap->port_task, delay);

        /* rc == 0 means that another user is using port task */
        WARN_ON(rc == 0);
}

/**
 *      ata_port_flush_task - Flush port_task
 *      @ap: The ata_port to flush port_task for
 *
 *      After this function completes, port_task is guranteed not to
 *      be running or scheduled.
 *
 *      LOCKING:
 *      Kernel thread context (may sleep)
 */
void ata_port_flush_task(struct ata_port *ap)
{
        unsigned long flags;

        DPRINTK("ENTER\n");

        spin_lock_irqsave(&ap->host_set->lock, flags);
        ap->flags |= ATA_FLAG_FLUSH_PORT_TASK;
        spin_unlock_irqrestore(&ap->host_set->lock, flags);

        DPRINTK("flush #1\n");
        flush_workqueue(ata_wq);

        /*
         * At this point, if a task is running, it's guaranteed to see
         * the FLUSH flag; thus, it will never queue pio tasks again.
         * Cancel and flush.
         */
        if (!cancel_delayed_work(&ap->port_task)) {
                DPRINTK("flush #2\n");
                flush_workqueue(ata_wq);
        }

        spin_lock_irqsave(&ap->host_set->lock, flags);
        ap->flags &= ~ATA_FLAG_FLUSH_PORT_TASK;
        spin_unlock_irqrestore(&ap->host_set->lock, flags);

        DPRINTK("EXIT\n");
}

void ata_qc_complete_internal(struct ata_queued_cmd *qc)
{
        struct completion *waiting = qc->private_data;

        qc->ap->ops->tf_read(qc->ap, &qc->tf);
        complete(waiting);
}

/**
 *      ata_exec_internal - execute libata internal command
 *      @ap: Port to which the command is sent
 *      @dev: Device to which the command is sent
 *      @tf: Taskfile registers for the command and the result
 *      @dma_dir: Data tranfer direction of the command
 *      @buf: Data buffer of the command
 *      @buflen: Length of data buffer
 *
 *      Executes libata internal command with timeout.  @tf contains
 *      command on entry and result on return.  Timeout and error
 *      conditions are reported via return value.  No recovery action
 *      is taken after a command times out.  It's caller's duty to
 *      clean up after timeout.
 *
 *      LOCKING:
 *      None.  Should be called with kernel context, might sleep.
 */

static unsigned
ata_exec_internal(struct ata_port *ap, struct ata_device *dev,
                  struct ata_taskfile *tf,
                  int dma_dir, void *buf, unsigned int buflen)
{
        u8 command = tf->command;
        struct ata_queued_cmd *qc;
        DECLARE_COMPLETION(wait);
        unsigned long flags;
        unsigned int err_mask;

        spin_lock_irqsave(&ap->host_set->lock, flags);

        qc = ata_qc_new_init(ap, dev);
        BUG_ON(qc == NULL);

        qc->tf = *tf;
        qc->dma_dir = dma_dir;
        if (dma_dir != DMA_NONE) {
                ata_sg_init_one(qc, buf, buflen);
                qc->nsect = buflen / ATA_SECT_SIZE;
        }

        qc->private_data = &wait;
        qc->complete_fn = ata_qc_complete_internal;

        qc->err_mask = ata_qc_issue(qc);
        if (qc->err_mask)
                ata_qc_complete(qc);

        spin_unlock_irqrestore(&ap->host_set->lock, flags);

        if (!wait_for_completion_timeout(&wait, ATA_TMOUT_INTERNAL)) {
                spin_lock_irqsave(&ap->host_set->lock, flags);

                /* We're racing with irq here.  If we lose, the
                 * following test prevents us from completing the qc
                 * again.  If completion irq occurs after here but
                 * before the caller cleans up, it will result in a
                 * spurious interrupt.  We can live with that.
                 */
                if (qc->flags & ATA_QCFLAG_ACTIVE) {
                        qc->err_mask = AC_ERR_TIMEOUT;
                        ata_qc_complete(qc);
                        printk(KERN_WARNING "ata%u: qc timeout (cmd 0x%x)\n",
                               ap->id, command);
                }

                spin_unlock_irqrestore(&ap->host_set->lock, flags);
        }

        *tf = qc->tf;
        err_mask = qc->err_mask;

        ata_qc_free(qc);

        return err_mask;
}

/**
 *      ata_pio_need_iordy      -       check if iordy needed
 *      @adev: ATA device
 *
 *      Check if the current speed of the device requires IORDY. Used
 *      by various controllers for chip configuration.
 */

unsigned int ata_pio_need_iordy(const struct ata_device *adev)
{
        int pio;
        int speed = adev->pio_mode - XFER_PIO_0;

        if (speed < 2)
                return 0;
        if (speed > 2)
                return 1;
                
        /* If we have no drive specific rule, then PIO 2 is non IORDY */

        if (adev->id[ATA_ID_FIELD_VALID] & 2) { /* EIDE */
                pio = adev->id[ATA_ID_EIDE_PIO];
                /* Is the speed faster than the drive allows non IORDY ? */
                if (pio) {
                        /* This is cycle times not frequency - watch the logic! */
                        if (pio > 240)  /* PIO2 is 240nS per cycle */
                                return 1;
                        return 0;
                }
        }
        return 0;
}

/**
 *      ata_dev_read_id - Read ID data from the specified device
 *      @ap: port on which target device resides
 *      @dev: target device
 *      @p_class: pointer to class of the target device (may be changed)
 *      @post_reset: is this read ID post-reset?
 *      @p_id: read IDENTIFY page (newly allocated)
 *
 *      Read ID data from the specified device.  ATA_CMD_ID_ATA is
 *      performed on ATA devices and ATA_CMD_ID_ATAPI on ATAPI
 *      devices.  This function also takes care of EDD signature
 *      misreporting (to be removed once EDD support is gone) and
 *      issues ATA_CMD_INIT_DEV_PARAMS for pre-ATA4 drives.
 *
 *      LOCKING:
 *      Kernel thread context (may sleep)
 *
 *      RETURNS:
 *      0 on success, -errno otherwise.
 */
static int ata_dev_read_id(struct ata_port *ap, struct ata_device *dev,
                           unsigned int *p_class, int post_reset, u16 **p_id)
{
        unsigned int class = *p_class;
        unsigned int using_edd;
        struct ata_taskfile tf;
        unsigned int err_mask = 0;
        u16 *id;
        const char *reason;
        int rc;

        DPRINTK("ENTER, host %u, dev %u\n", ap->id, dev->devno);

        if (ap->ops->probe_reset ||
            ap->flags & (ATA_FLAG_SRST | ATA_FLAG_SATA_RESET))
                using_edd = 0;
        else
                using_edd = 1;

        ata_dev_select(ap, dev->devno, 1, 1); /* select device 0/1 */

        id = kmalloc(sizeof(id[0]) * ATA_ID_WORDS, GFP_KERNEL);
        if (id == NULL) {
                rc = -ENOMEM;
                reason = "out of memory";
                goto err_out;
        }

 retry:
        ata_tf_init(ap, &tf, dev->devno);

        switch (class) {
        case ATA_DEV_ATA:
                tf.command = ATA_CMD_ID_ATA;
                break;
        case ATA_DEV_ATAPI:
                tf.command = ATA_CMD_ID_ATAPI;
                break;
        default:
                rc = -ENODEV;
                reason = "unsupported class";
                goto err_out;
        }

        tf.protocol = ATA_PROT_PIO;

        err_mask = ata_exec_internal(ap, dev, &tf, DMA_FROM_DEVICE,
                                     id, sizeof(id[0]) * ATA_ID_WORDS);

        if (err_mask) {
                rc = -EIO;
                reason = "I/O error";

                if (err_mask & ~AC_ERR_DEV)
                        goto err_out;

                /*
                 * arg!  EDD works for all test cases, but seems to return
                 * the ATA signature for some ATAPI devices.  Until the
                 * reason for this is found and fixed, we fix up the mess
                 * here.  If IDENTIFY DEVICE returns command aborted
                 * (as ATAPI devices do), then we issue an
                 * IDENTIFY PACKET DEVICE.
                 *
                 * ATA software reset (SRST, the default) does not appear
                 * to have this problem.
                 */
                if ((using_edd) && (class == ATA_DEV_ATA)) {
                        u8 err = tf.feature;
                        if (err & ATA_ABORTED) {
                                class = ATA_DEV_ATAPI;
                                goto retry;
                        }
                }
                goto err_out;
        }

        swap_buf_le16(id, ATA_ID_WORDS);

        /* print device capabilities */
        printk(KERN_DEBUG "ata%u: dev %u cfg "
               "49:%04x 82:%04x 83:%04x 84:%04x 85:%04x 86:%04x 87:%04x 88:%04x\n",
               ap->id, dev->devno,
               id[49], id[82], id[83], id[84], id[85], id[86], id[87], id[88]);

        /* sanity check */
        if ((class == ATA_DEV_ATA) != ata_id_is_ata(id)) {
                rc = -EINVAL;
                reason = "device reports illegal type";
                goto err_out;
        }

        if (post_reset && class == ATA_DEV_ATA) {
                /*
                 * The exact sequence expected by certain pre-ATA4 drives is:
                 * SRST RESET
                 * IDENTIFY
                 * INITIALIZE DEVICE PARAMETERS
                 * anything else..
                 * Some drives were very specific about that exact sequence.
                 */
                if (ata_id_major_version(id) < 4 || !ata_id_has_lba(id)) {
                        err_mask = ata_dev_init_params(ap, dev);
                        if (err_mask) {
                                rc = -EIO;
                                reason = "INIT_DEV_PARAMS failed";
                                goto err_out;
                        }

                        /* current CHS translation info (id[53-58]) might be
                         * changed. reread the identify device info.
                         */
                        post_reset = 0;
                        goto retry;
                }
        }

        *p_class = class;
        *p_id = id;
        return 0;

 err_out:
        printk(KERN_WARNING "ata%u: dev %u failed to IDENTIFY (%s)\n",
               ap->id, dev->devno, reason);
        kfree(id);
        return rc;
}

static inline u8 ata_dev_knobble(const struct ata_port *ap,
                                 struct ata_device *dev)
{
        return ((ap->cbl == ATA_CBL_SATA) && (!ata_id_is_sata(dev->id)));
}

/**
 *      ata_dev_configure - Configure the specified ATA/ATAPI device
 *      @ap: Port on which target device resides
 *      @dev: Target device to configure
 *      @print_info: Enable device info printout
 *
 *      Configure @dev according to @dev->id.  Generic and low-level
 *      driver specific fixups are also applied.
 *
 *      LOCKING:
 *      Kernel thread context (may sleep)
 *
 *      RETURNS:
 *      0 on success, -errno otherwise
 */
static int ata_dev_configure(struct ata_port *ap, struct ata_device *dev,
                             int print_info)
{
        unsigned int xfer_mask;
        int i, rc;

        if (!ata_dev_present(dev)) {
                DPRINTK("ENTER/EXIT (host %u, dev %u) -- nodev\n",
                        ap->id, dev->devno);
                return 0;
        }

        DPRINTK("ENTER, host %u, dev %u\n", ap->id, dev->devno);

        /* initialize to-be-configured parameters */
        dev->flags = 0;
        dev->max_sectors = 0;
        dev->cdb_len = 0;
        dev->n_sectors = 0;
        dev->cylinders = 0;
        dev->heads = 0;
        dev->sectors = 0;

        /*
         * common ATA, ATAPI feature tests
         */

        /* we require DMA support (bits 8 of word 49) */
        if (!ata_id_has_dma(dev->id)) {
                printk(KERN_DEBUG "ata%u: no dma\n", ap->id);
                rc = -EINVAL;
                goto err_out_nosup;
        }

        /* find max transfer mode; for printk only */
        xfer_mask = ata_id_xfermask(dev->id);

        ata_dump_id(dev->id);

        /* ATA-specific feature tests */
        if (dev->class == ATA_DEV_ATA) {
                dev->n_sectors = ata_id_n_sectors(dev->id);

                if (ata_id_has_lba(dev->id)) {
                        const char *lba_desc;

                        lba_desc = "LBA";
                        dev->flags |= ATA_DFLAG_LBA;
                        if (ata_id_has_lba48(dev->id)) {
                                dev->flags |= ATA_DFLAG_LBA48;
                                lba_desc = "LBA48";
                        }

                        /* print device info to dmesg */
                        if (print_info)
                                printk(KERN_INFO "ata%u: dev %u ATA-%d, "
                                       "max %s, %Lu sectors: %s\n",
                                       ap->id, dev->devno,
                                       ata_id_major_version(dev->id),
                                       ata_mode_string(xfer_mask),
                                       (unsigned long long)dev->n_sectors,
                                       lba_desc);
                } else {
                        /* CHS */

                        /* Default translation */
                        dev->cylinders  = dev->id[1];
                        dev->heads      = dev->id[3];
                        dev->sectors    = dev->id[6];

                        if (ata_id_current_chs_valid(dev->id)) {
                                /* Current CHS translation is valid. */
                                dev->cylinders = dev->id[54];
                                dev->heads     = dev->id[55];
                                dev->sectors   = dev->id[56];
                        }

                        /* print device info to dmesg */
                        if (print_info)
                                printk(KERN_INFO "ata%u: dev %u ATA-%d, "
                                       "max %s, %Lu sectors: CHS %u/%u/%u\n",
                                       ap->id, dev->devno,
                                       ata_id_major_version(dev->id),
                                       ata_mode_string(xfer_mask),
                                       (unsigned long long)dev->n_sectors,
                                       dev->cylinders, dev->heads, dev->sectors);
                }

                dev->cdb_len = 16;
        }

        /* ATAPI-specific feature tests */
        else if (dev->class == ATA_DEV_ATAPI) {
                rc = atapi_cdb_len(dev->id);
                if ((rc < 12) || (rc > ATAPI_CDB_LEN)) {
                        printk(KERN_WARNING "ata%u: unsupported CDB len\n", ap->id);
                        rc = -EINVAL;
                        goto err_out_nosup;
                }
                dev->cdb_len = (unsigned int) rc;

                /* print device info to dmesg */
                if (print_info)
                        printk(KERN_INFO "ata%u: dev %u ATAPI, max %s\n",
                               ap->id, dev->devno, ata_mode_string(xfer_mask));
        }

        ap->host->max_cmd_len = 0;
        for (i = 0; i < ATA_MAX_DEVICES; i++)
                ap->host->max_cmd_len = max_t(unsigned int,
                                              ap->host->max_cmd_len,
                                              ap->device[i].cdb_len);

        /* limit bridge transfers to udma5, 200 sectors */
        if (ata_dev_knobble(ap, dev)) {
                if (print_info)
                        printk(KERN_INFO "ata%u(%u): applying bridge limits\n",
                               ap->id, dev->devno);
                ap->udma_mask &= ATA_UDMA5;
                dev->max_sectors = ATA_MAX_SECTORS;
        }

        if (ap->ops->dev_config)
                ap->ops->dev_config(ap, dev);

        DPRINTK("EXIT, drv_stat = 0x%x\n", ata_chk_status(ap));
        return 0;

err_out_nosup:
        printk(KERN_WARNING "ata%u: dev %u not supported, ignoring\n",
               ap->id, dev->devno);
        DPRINTK("EXIT, err\n");
        return rc;
}

/**
 *      ata_bus_probe - Reset and probe ATA bus
 *      @ap: Bus to probe
 *
 *      Master ATA bus probing function.  Initiates a hardware-dependent
 *      bus reset, then attempts to identify any devices found on
 *      the bus.
 *
 *      LOCKING:
 *      PCI/etc. bus probe sem.
 *
 *      RETURNS:
 *      Zero on success, non-zero on error.
 */

static int ata_bus_probe(struct ata_port *ap)
{
        unsigned int classes[ATA_MAX_DEVICES];
        unsigned int i, rc, found = 0;

        ata_port_probe(ap);

        /* reset */
        if (ap->ops->probe_reset) {
                rc = ap->ops->probe_reset(ap, classes);
                if (rc) {
                        printk("ata%u: reset failed (errno=%d)\n", ap->id, rc);
                        return rc;
                }

                for (i = 0; i < ATA_MAX_DEVICES; i++)
                        if (classes[i] == ATA_DEV_UNKNOWN)
                                classes[i] = ATA_DEV_NONE;
        } else {
                ap->ops->phy_reset(ap);

                for (i = 0; i < ATA_MAX_DEVICES; i++) {
                        if (!(ap->flags & ATA_FLAG_PORT_DISABLED))
                                classes[i] = ap->device[i].class;
                        else
                                ap->device[i].class = ATA_DEV_UNKNOWN;
                }
                ata_port_probe(ap);
        }

        /* read IDENTIFY page and configure devices */
        for (i = 0; i < ATA_MAX_DEVICES; i++) {
                struct ata_device *dev = &ap->device[i];

                dev->class = classes[i];

                if (!ata_dev_present(dev))
                        continue;

                WARN_ON(dev->id != NULL);
                if (ata_dev_read_id(ap, dev, &dev->class, 1, &dev->id)) {
                        dev->class = ATA_DEV_NONE;
                        continue;
                }

                if (ata_dev_configure(ap, dev, 1)) {
                        dev->class++;   /* disable device */
                        continue;
                }

                found = 1;
        }

        if (!found)
                goto err_out_disable;

        ata_set_mode(ap);
        if (ap->flags & ATA_FLAG_PORT_DISABLED)
                goto err_out_disable;

        return 0;

err_out_disable:
        ap->ops->port_disable(ap);
        return -1;
}

/**
 *      ata_port_probe - Mark port as enabled
 *      @ap: Port for which we indicate enablement
 *
 *      Modify @ap data structure such that the system
 *      thinks that the entire port is enabled.
 *
 *      LOCKING: host_set lock, or some other form of
 *      serialization.
 */

void ata_port_probe(struct ata_port *ap)
{
        ap->flags &= ~ATA_FLAG_PORT_DISABLED;
}

/**
 *      sata_print_link_status - Print SATA link status
 *      @ap: SATA port to printk link status about
 *
 *      This function prints link speed and status of a SATA link.
 *
 *      LOCKING:
 *      None.
 */
static void sata_print_link_status(struct ata_port *ap)
{
        u32 sstatus, tmp;
        const char *speed;

        if (!ap->ops->scr_read)
                return;

        sstatus = scr_read(ap, SCR_STATUS);

        if (sata_dev_present(ap)) {
                tmp = (sstatus >> 4) & 0xf;
                if (tmp & (1 << 0))
                        speed = "1.5";
                else if (tmp & (1 << 1))
                        speed = "3.0";
                else
                        speed = "<unknown>";
                printk(KERN_INFO "ata%u: SATA link up %s Gbps (SStatus %X)\n",
                       ap->id, speed, sstatus);
        } else {
                printk(KERN_INFO "ata%u: SATA link down (SStatus %X)\n",
                       ap->id, sstatus);
        }
}

/**
 *      __sata_phy_reset - Wake/reset a low-level SATA PHY
 *      @ap: SATA port associated with target SATA PHY.
 *
 *      This function issues commands to standard SATA Sxxx
 *      PHY registers, to wake up the phy (and device), and
 *      clear any reset condition.
 *
 *      LOCKING:
 *      PCI/etc. bus probe sem.
 *
 */
void __sata_phy_reset(struct ata_port *ap)
{
        u32 sstatus;
        unsigned long timeout = jiffies + (HZ * 5);

        if (ap->flags & ATA_FLAG_SATA_RESET) {
                /* issue phy wake/reset */
                scr_write_flush(ap, SCR_CONTROL, 0x301);
                /* Couldn't find anything in SATA I/II specs, but
                 * AHCI-1.1 10.4.2 says at least 1 ms. */
                mdelay(1);
        }
        scr_write_flush(ap, SCR_CONTROL, 0x300); /* phy wake/clear reset */

        /* wait for phy to become ready, if necessary */
        do {
                msleep(200);
                sstatus = scr_read(ap, SCR_STATUS);
                if ((sstatus & 0xf) != 1)
                        break;
        } while (time_before(jiffies, timeout));

        /* print link status */
        sata_print_link_status(ap);

        /* TODO: phy layer with polling, timeouts, etc. */
        if (sata_dev_present(ap))
                ata_port_probe(ap);
        else
                ata_port_disable(ap);

        if (ap->flags & ATA_FLAG_PORT_DISABLED)
                return;

        if (ata_busy_sleep(ap, ATA_TMOUT_BOOT_QUICK, ATA_TMOUT_BOOT)) {
                ata_port_disable(ap);
                return;
        }

        ap->cbl = ATA_CBL_SATA;
}

/**
 *      sata_phy_reset - Reset SATA bus.
 *      @ap: SATA port associated with target SATA PHY.
 *
 *      This function resets the SATA bus, and then probes
 *      the bus for devices.
 *
 *      LOCKING:
 *      PCI/etc. bus probe sem.
 *
 */
void sata_phy_reset(struct ata_port *ap)
{
        __sata_phy_reset(ap);
        if (ap->flags & ATA_FLAG_PORT_DISABLED)
                return;
        ata_bus_reset(ap);
}

/**
 *      ata_port_disable - Disable port.
 *      @ap: Port to be disabled.
 *
 *      Modify @ap data structure such that the system
 *      thinks that the entire port is disabled, and should
 *      never attempt to probe or communicate with devices
 *      on this port.
 *
 *      LOCKING: host_set lock, or some other form of
 *      serialization.
 */

void ata_port_disable(struct ata_port *ap)
{
        ap->device[0].class = ATA_DEV_NONE;
        ap->device[1].class = ATA_DEV_NONE;
        ap->flags |= ATA_FLAG_PORT_DISABLED;
}

/*
 * This mode timing computation functionality is ported over from
 * drivers/ide/ide-timing.h and was originally written by Vojtech Pavlik
 */
/*
 * PIO 0-5, MWDMA 0-2 and UDMA 0-6 timings (in nanoseconds).
 * These were taken from ATA/ATAPI-6 standard, rev 0a, except
 * for PIO 5, which is a nonstandard extension and UDMA6, which
 * is currently supported only by Maxtor drives. 
 */

static const struct ata_timing ata_timing[] = {

        { XFER_UDMA_6,     0,   0,   0,   0,   0,   0,   0,  15 },
        { XFER_UDMA_5,     0,   0,   0,   0,   0,   0,   0,  20 },
        { XFER_UDMA_4,     0,   0,   0,   0,   0,   0,   0,  30 },
        { XFER_UDMA_3,     0,   0,   0,   0,   0,   0,   0,  45 },

        { XFER_UDMA_2,     0,   0,   0,   0,   0,   0,   0,  60 },
        { XFER_UDMA_1,     0,   0,   0,   0,   0,   0,   0,  80 },
        { XFER_UDMA_0,     0,   0,   0,   0,   0,   0,   0, 120 },

/*      { XFER_UDMA_SLOW,  0,   0,   0,   0,   0,   0,   0, 150 }, */
                                          
        { XFER_MW_DMA_2,  25,   0,   0,   0,  70,  25, 120,   0 },
        { XFER_MW_DMA_1,  45,   0,   0,   0,  80,  50, 150,   0 },
        { XFER_MW_DMA_0,  60,   0,   0,   0, 215, 215, 480,   0 },
                                          
        { XFER_SW_DMA_2,  60,   0,   0,   0, 120, 120, 240,   0 },
        { XFER_SW_DMA_1,  90,   0,   0,   0, 240, 240, 480,   0 },
        { XFER_SW_DMA_0, 120,   0,   0,   0, 480, 480, 960,   0 },

/*      { XFER_PIO_5,     20,  50,  30, 100,  50,  30, 100,   0 }, */
        { XFER_PIO_4,     25,  70,  25, 120,  70,  25, 120,   0 },
        { XFER_PIO_3,     30,  80,  70, 180,  80,  70, 180,   0 },

        { XFER_PIO_2,     30, 290,  40, 330, 100,  90, 240,   0 },
        { XFER_PIO_1,     50, 290,  93, 383, 125, 100, 383,   0 },
        { XFER_PIO_0,     70, 290, 240, 600, 165, 150, 600,   0 },

/*      { XFER_PIO_SLOW, 120, 290, 240, 960, 290, 240, 960,   0 }, */

        { 0xFF }
};

#define ENOUGH(v,unit)          (((v)-1)/(unit)+1)
#define EZ(v,unit)              ((v)?ENOUGH(v,unit):0)

static void ata_timing_quantize(const struct ata_timing *t, struct ata_timing *q, int T, int UT)
{
        q->setup   = EZ(t->setup   * 1000,  T);
        q->act8b   = EZ(t->act8b   * 1000,  T);
        q->rec8b   = EZ(t->rec8b   * 1000,  T);
        q->cyc8b   = EZ(t->cyc8b   * 1000,  T);
        q->active  = EZ(t->active  * 1000,  T);
        q->recover = EZ(t->recover * 1000,  T);
        q->cycle   = EZ(t->cycle   * 1000,  T);
        q->udma    = EZ(t->udma    * 1000, UT);
}

void ata_timing_merge(const struct ata_timing *a, const struct ata_timing *b,
                      struct ata_timing *m, unsigned int what)
{
        if (what & ATA_TIMING_SETUP  ) m->setup   = max(a->setup,   b->setup);
        if (what & ATA_TIMING_ACT8B  ) m->act8b   = max(a->act8b,   b->act8b);
        if (what & ATA_TIMING_REC8B  ) m->rec8b   = max(a->rec8b,   b->rec8b);
        if (what & ATA_TIMING_CYC8B  ) m->cyc8b   = max(a->cyc8b,   b->cyc8b);
        if (what & ATA_TIMING_ACTIVE ) m->active  = max(a->active,  b->active);
        if (what & ATA_TIMING_RECOVER) m->recover = max(a->recover, b->recover);
        if (what & ATA_TIMING_CYCLE  ) m->cycle   = max(a->cycle,   b->cycle);
        if (what & ATA_TIMING_UDMA   ) m->udma    = max(a->udma,    b->udma);
}

static const struct ata_timing* ata_timing_find_mode(unsigned short speed)
{
        const struct ata_timing *t;

        for (t = ata_timing; t->mode != speed; t++)
                if (t->mode == 0xFF)
                        return NULL;
        return t; 
}

int ata_timing_compute(struct ata_device *adev, unsigned short speed,
                       struct ata_timing *t, int T, int UT)
{
        const struct ata_timing *s;
        struct ata_timing p;

        /*
         * Find the mode. 
         */

        if (!(s = ata_timing_find_mode(speed)))
                return -EINVAL;

        memcpy(t, s, sizeof(*s));

        /*
         * If the drive is an EIDE drive, it can tell us it needs extended
         * PIO/MW_DMA cycle timing.
         */

        if (adev->id[ATA_ID_FIELD_VALID] & 2) { /* EIDE drive */
                memset(&p, 0, sizeof(p));
                if(speed >= XFER_PIO_0 && speed <= XFER_SW_DMA_0) {
                        if (speed <= XFER_PIO_2) p.cycle = p.cyc8b = adev->id[ATA_ID_EIDE_PIO];
                                            else p.cycle = p.cyc8b = adev->id[ATA_ID_EIDE_PIO_IORDY];
                } else if(speed >= XFER_MW_DMA_0 && speed <= XFER_MW_DMA_2) {
                        p.cycle = adev->id[ATA_ID_EIDE_DMA_MIN];
                }
                ata_timing_merge(&p, t, t, ATA_TIMING_CYCLE | ATA_TIMING_CYC8B);
        }

        /*
         * Convert the timing to bus clock counts.
         */

        ata_timing_quantize(t, t, T, UT);

        /*
         * Even in DMA/UDMA modes we still use PIO access for IDENTIFY,
         * S.M.A.R.T * and some other commands. We have to ensure that the
         * DMA cycle timing is slower/equal than the fastest PIO timing.
         */

        if (speed > XFER_PIO_4) {
                ata_timing_compute(adev, adev->pio_mode, &p, T, UT);
                ata_timing_merge(&p, t, t, ATA_TIMING_ALL);
        }

        /*
         * Lengthen active & recovery time so that cycle time is correct.
         */

        if (t->act8b + t->rec8b < t->cyc8b) {
                t->act8b += (t->cyc8b - (t->act8b + t->rec8b)) / 2;
                t->rec8b = t->cyc8b - t->act8b;
        }

        if (t->active + t->recover < t->cycle) {
                t->active += (t->cycle - (t->active + t->recover)) / 2;
                t->recover = t->cycle - t->active;
        }

        return 0;
}

static const struct {
        unsigned int shift;
        u8 base;
} xfer_mode_classes[] = {
        { ATA_SHIFT_UDMA,       XFER_UDMA_0 },
        { ATA_SHIFT_MWDMA,      XFER_MW_DMA_0 },
        { ATA_SHIFT_PIO,        XFER_PIO_0 },
};

static u8 base_from_shift(unsigned int shift)
{
        int i;

        for (i = 0; i < ARRAY_SIZE(xfer_mode_classes); i++)
                if (xfer_mode_classes[i].shift == shift)
                        return xfer_mode_classes[i].base;

        return 0xff;
}

static void ata_dev_set_mode(struct ata_port *ap, struct ata_device *dev)
{
        if (!ata_dev_present(dev) || (ap->flags & ATA_FLAG_PORT_DISABLED))
                return;

        if (dev->xfer_shift == ATA_SHIFT_PIO)
                dev->flags |= ATA_DFLAG_PIO;

        ata_dev_set_xfermode(ap, dev);

        if (ata_dev_revalidate(ap, dev, 0)) {
                printk(KERN_ERR "ata%u: failed to revalidate after set "
                       "xfermode, disabled\n", ap->id);
                ata_port_disable(ap);
        }

        DPRINTK("xfer_shift=%u, xfer_mode=0x%x\n",
                dev->xfer_shift, (int)dev->xfer_mode);

        printk(KERN_INFO "ata%u: dev %u configured for %s\n",
               ap->id, dev->devno,
               ata_mode_string(ata_xfer_mode2mask(dev->xfer_mode)));
}

static int ata_host_set_pio(struct ata_port *ap)
{
        unsigned int mask;
        int x, i;
        u8 base, xfer_mode;

        mask = ata_get_mode_mask(ap, ATA_SHIFT_PIO);
        x = fgb(mask);
        if (x < 0) {
                printk(KERN_WARNING "ata%u: no PIO support\n", ap->id);
                return -1;
        }

        base = base_from_shift(ATA_SHIFT_PIO);
        xfer_mode = base + x;

        DPRINTK("base 0x%x xfer_mode 0x%x mask 0x%x x %d\n",
                (int)base, (int)xfer_mode, mask, x);

        for (i = 0; i < ATA_MAX_DEVICES; i++) {
                struct ata_device *dev = &ap->device[i];
                if (ata_dev_present(dev)) {
                        dev->pio_mode = xfer_mode;
                        dev->xfer_mode = xfer_mode;
                        dev->xfer_shift = ATA_SHIFT_PIO;
                        if (ap->ops->set_piomode)
                                ap->ops->set_piomode(ap, dev);
                }
        }

        return 0;
}

static void ata_host_set_dma(struct ata_port *ap, u8 xfer_mode,
                            unsigned int xfer_shift)
{
        int i;

        for (i = 0; i < ATA_MAX_DEVICES; i++) {
                struct ata_device *dev = &ap->device[i];
                if (ata_dev_present(dev)) {
                        dev->dma_mode = xfer_mode;
                        dev->xfer_mode = xfer_mode;
                        dev->xfer_shift = xfer_shift;
                        if (ap->ops->set_dmamode)
                                ap->ops->set_dmamode(ap, dev);
                }
        }
}

/**
 *      ata_set_mode - Program timings and issue SET FEATURES - XFER
 *      @ap: port on which timings will be programmed
 *
 *      Set ATA device disk transfer mode (PIO3, UDMA6, etc.).
 *
 *      LOCKING:
 *      PCI/etc. bus probe sem.
 */
static void ata_set_mode(struct ata_port *ap)
{
        unsigned int xfer_shift;
        u8 xfer_mode;
        int rc;

        /* step 1: always set host PIO timings */
        rc = ata_host_set_pio(ap);
        if (rc)
                goto err_out;

        /* step 2: choose the best data xfer mode */
        xfer_mode = xfer_shift = 0;
        rc = ata_choose_xfer_mode(ap, &xfer_mode, &xfer_shift);
        if (rc)
                goto err_out;

        /* step 3: if that xfer mode isn't PIO, set host DMA timings */
        if (xfer_shift != ATA_SHIFT_PIO)
                ata_host_set_dma(ap, xfer_mode, xfer_shift);

        /* step 4: update devices' xfer mode */
        ata_dev_set_mode(ap, &ap->device[0]);
        ata_dev_set_mode(ap, &ap->device[1]);

        if (ap->flags & ATA_FLAG_PORT_DISABLED)
                return;

        if (ap->ops->post_set_mode)
                ap->ops->post_set_mode(ap);

        return;

err_out:
        ata_port_disable(ap);
}

/**
 *      ata_tf_to_host - issue ATA taskfile to host controller
 *      @ap: port to which command is being issued
 *      @tf: ATA taskfile register set
 *
 *      Issues ATA taskfile register set to ATA host controller,
 *      with proper synchronization with interrupt handler and
 *      other threads.
 *
 *      LOCKING:
 *      spin_lock_irqsave(host_set lock)
 */

static inline void ata_tf_to_host(struct ata_port *ap,
                                  const struct ata_taskfile *tf)
{
        ap->ops->tf_load(ap, tf);
        ap->ops->exec_command(ap, tf);
}

/**
 *      ata_busy_sleep - sleep until BSY clears, or timeout
 *      @ap: port containing status register to be polled
 *      @tmout_pat: impatience timeout
 *      @tmout: overall timeout
 *
 *      Sleep until ATA Status register bit BSY clears,
 *      or a timeout occurs.
 *
 *      LOCKING: None.
 */

unsigned int ata_busy_sleep (struct ata_port *ap,
                             unsigned long tmout_pat, unsigned long tmout)
{
        unsigned long timer_start, timeout;
        u8 status;

        status = ata_busy_wait(ap, ATA_BUSY, 300);
        timer_start = jiffies;
        timeout = timer_start + tmout_pat;
        while ((status & ATA_BUSY) && (time_before(jiffies, timeout))) {
                msleep(50);
                status = ata_busy_wait(ap, ATA_BUSY, 3);
        }

        if (status & ATA_BUSY)
                printk(KERN_WARNING "ata%u is slow to respond, "
                       "please be patient\n", ap->id);

        timeout = timer_start + tmout;
        while ((status & ATA_BUSY) && (time_before(jiffies, timeout))) {
                msleep(50);
                status = ata_chk_status(ap);
        }

        if (status & ATA_BUSY) {
                printk(KERN_ERR "ata%u failed to respond (%lu secs)\n",
                       ap->id, tmout / HZ);
                return 1;
        }

        return 0;
}

static void ata_bus_post_reset(struct ata_port *ap, unsigned int devmask)
{
        struct ata_ioports *ioaddr = &ap->ioaddr;
        unsigned int dev0 = devmask & (1 << 0);
        unsigned int dev1 = devmask & (1 << 1);
        unsigned long timeout;

        /* if device 0 was found in ata_devchk, wait for its
         * BSY bit to clear
         */
        if (dev0)
                ata_busy_sleep(ap, ATA_TMOUT_BOOT_QUICK, ATA_TMOUT_BOOT);

        /* if device 1 was found in ata_devchk, wait for
         * register access, then wait for BSY to clear
         */
        timeout = jiffies + ATA_TMOUT_BOOT;
        while (dev1) {
                u8 nsect, lbal;

                ap->ops->dev_select(ap, 1);
                if (ap->flags & ATA_FLAG_MMIO) {
                        nsect = readb((void __iomem *) ioaddr->nsect_addr);
                        lbal = readb((void __iomem *) ioaddr->lbal_addr);
                } else {
                        nsect = inb(ioaddr->nsect_addr);
                        lbal = inb(ioaddr->lbal_addr);
                }
                if ((nsect == 1) && (lbal == 1))
                        break;
                if (time_after(jiffies, timeout)) {
                        dev1 = 0;
                        break;
                }
                msleep(50);     /* give drive a breather */
        }
        if (dev1)
                ata_busy_sleep(ap, ATA_TMOUT_BOOT_QUICK, ATA_TMOUT_BOOT);

        /* is all this really necessary? */
        ap->ops->dev_select(ap, 0);
        if (dev1)
                ap->ops->dev_select(ap, 1);
        if (dev0)
                ap->ops->dev_select(ap, 0);
}

/**
 *      ata_bus_edd - Issue EXECUTE DEVICE DIAGNOSTIC command.
 *      @ap: Port to reset and probe
 *
 *      Use the EXECUTE DEVICE DIAGNOSTIC command to reset and
 *      probe the bus.  Not often used these days.
 *
 *      LOCKING:
 *      PCI/etc. bus probe sem.
 *      Obtains host_set lock.
 *
 */

static unsigned int ata_bus_edd(struct ata_port *ap)
{
        struct ata_taskfile tf;
        unsigned long flags;

        /* set up execute-device-diag (bus reset) taskfile */
        /* also, take interrupts to a known state (disabled) */
        DPRINTK("execute-device-diag\n");
        ata_tf_init(ap, &tf, 0);
        tf.ctl |= ATA_NIEN;
        tf.command = ATA_CMD_EDD;
        tf.protocol = ATA_PROT_NODATA;

        /* do bus reset */
        spin_lock_irqsave(&ap->host_set->lock, flags);
        ata_tf_to_host(ap, &tf);
        spin_unlock_irqrestore(&ap->host_set->lock, flags);

        /* spec says at least 2ms.  but who knows with those
         * crazy ATAPI devices...
         */
        msleep(150);

        return ata_busy_sleep(ap, ATA_TMOUT_BOOT_QUICK, ATA_TMOUT_BOOT);
}

static unsigned int ata_bus_softreset(struct ata_port *ap,
                                      unsigned int devmask)
{
        struct ata_ioports *ioaddr = &ap->ioaddr;

        DPRINTK("ata%u: bus reset via SRST\n", ap->id);

        /* software reset.  causes dev0 to be selected */
        if (ap->flags & ATA_FLAG_MMIO) {
                writeb(ap->ctl, (void __iomem *) ioaddr->ctl_addr);
                udelay(20);     /* FIXME: flush */
                writeb(ap->ctl | ATA_SRST, (void __iomem *) ioaddr->ctl_addr);
                udelay(20);     /* FIXME: flush */
                writeb(ap->ctl, (void __iomem *) ioaddr->ctl_addr);
        } else {
                outb(ap->ctl, ioaddr->ctl_addr);
                udelay(10);
                outb(ap->ctl | ATA_SRST, ioaddr->ctl_addr);
                udelay(10);
                outb(ap->ctl, ioaddr->ctl_addr);
        }

        /* spec mandates ">= 2ms" before checking status.
         * We wait 150ms, because that was the magic delay used for
         * ATAPI devices in Hale Landis's ATADRVR, for the period of time
         * between when the ATA command register is written, and then
         * status is checked.  Because waiting for "a while" before
         * checking status is fine, post SRST, we perform this magic
         * delay here as well.
         */
        msleep(150);

        ata_bus_post_reset(ap, devmask);

        return 0;
}

/**
 *      ata_bus_reset - reset host port and associated ATA channel
 *      @ap: port to reset
 *
 *      This is typically the first time we actually start issuing
 *      commands to the ATA channel.  We wait for BSY to clear, then
 *      issue EXECUTE DEVICE DIAGNOSTIC command, polling for its
 *      result.  Determine what devices, if any, are on the channel
 *      by looking at the device 0/1 error register.  Look at the signature
 *      stored in each device's taskfile registers, to determine if
 *      the device is ATA or ATAPI.
 *
 *      LOCKING:
 *      PCI/etc. bus probe sem.
 *      Obtains host_set lock.
 *
 *      SIDE EFFECTS:
 *      Sets ATA_FLAG_PORT_DISABLED if bus reset fails.
 */

void ata_bus_reset(struct ata_port *ap)
{
        struct ata_ioports *ioaddr = &ap->ioaddr;
        unsigned int slave_possible = ap->flags & ATA_FLAG_SLAVE_POSS;
        u8 err;
        unsigned int dev0, dev1 = 0, rc = 0, devmask = 0;

        DPRINTK("ENTER, host %u, port %u\n", ap->id, ap->port_no);

        /* determine if device 0/1 are present */
        if (ap->flags & ATA_FLAG_SATA_RESET)
                dev0 = 1;
        else {
                dev0 = ata_devchk(ap, 0);
                if (slave_possible)
                        dev1 = ata_devchk(ap, 1);
        }

        if (dev0)
                devmask |= (1 << 0);
        if (dev1)
                devmask |= (1 << 1);

        /* select device 0 again */
        ap->ops->dev_select(ap, 0);

        /* issue bus reset */
        if (ap->flags & ATA_FLAG_SRST)
                rc = ata_bus_softreset(ap, devmask);
        else if ((ap->flags & ATA_FLAG_SATA_RESET) == 0) {
                /* set up device control */
                if (ap->flags & ATA_FLAG_MMIO)
                        writeb(ap->ctl, (void __iomem *) ioaddr->ctl_addr);
                else
                        outb(ap->ctl, ioaddr->ctl_addr);
                rc = ata_bus_edd(ap);
        }

        if (rc)
                goto err_out;

        /*
         * determine by signature whether we have ATA or ATAPI devices
         */
        ap->device[0].class = ata_dev_try_classify(ap, 0, &err);
        if ((slave_possible) && (err != 0x81))
                ap->device[1].class = ata_dev_try_classify(ap, 1, &err);

        /* re-enable interrupts */
        if (ap->ioaddr.ctl_addr)        /* FIXME: hack. create a hook instead */
                ata_irq_on(ap);

        /* is double-select really necessary? */
        if (ap->device[1].class != ATA_DEV_NONE)
                ap->ops->dev_select(ap, 1);
        if (ap->device[0].class != ATA_DEV_NONE)
                ap->ops->dev_select(ap, 0);

        /* if no devices were detected, disable this port */
        if ((ap->device[0].class == ATA_DEV_NONE) &&
            (ap->device[1].class == ATA_DEV_NONE))
                goto err_out;

        if (ap->flags & (ATA_FLAG_SATA_RESET | ATA_FLAG_SRST)) {
                /* set up device control for ATA_FLAG_SATA_RESET */
                if (ap->flags & ATA_FLAG_MMIO)
                        writeb(ap->ctl, (void __iomem *) ioaddr->ctl_addr);
                else
                        outb(ap->ctl, ioaddr->ctl_addr);
        }

        DPRINTK("EXIT\n");
        return;

err_out:
        printk(KERN_ERR "ata%u: disabling port\n", ap->id);
        ap->ops->port_disable(ap);

        DPRINTK("EXIT\n");
}

static int sata_phy_resume(struct ata_port *ap)
{
        unsigned long timeout = jiffies + (HZ * 5);
        u32 sstatus;

        scr_write_flush(ap, SCR_CONTROL, 0x300);

        /* Wait for phy to become ready, if necessary. */
        do {
                msleep(200);
                sstatus = scr_read(ap, SCR_STATUS);
                if ((sstatus & 0xf) != 1)
                        return 0;
        } while (time_before(jiffies, timeout));

        return -1;
}

/**
 *      ata_std_probeinit - initialize probing
 *      @ap: port to be probed
 *
 *      @ap is about to be probed.  Initialize it.  This function is
 *      to be used as standard callback for ata_drive_probe_reset().
 *
 *      NOTE!!! Do not use this function as probeinit if a low level
 *      driver implements only hardreset.  Just pass NULL as probeinit
 *      in that case.  Using this function is probably okay but doing
 *      so makes reset sequence different from the original
 *      ->phy_reset implementation and Jeff nervous.  :-P
 */
extern void ata_std_probeinit(struct ata_port *ap)
{
        if (ap->flags & ATA_FLAG_SATA && ap->ops->scr_read) {
                sata_phy_resume(ap);
                if (sata_dev_present(ap))
                        ata_busy_sleep(ap, ATA_TMOUT_BOOT_QUICK, ATA_TMOUT_BOOT);
        }
}

/**
 *      ata_std_softreset - reset host port via ATA SRST
 *      @ap: port to reset
 *      @verbose: fail verbosely
 *      @classes: resulting classes of attached devices
 *
 *      Reset host port using ATA SRST.  This function is to be used
 *      as standard callback for ata_drive_*_reset() functions.
 *
 *      LOCKING:
 *      Kernel thread context (may sleep)
 *
 *      RETURNS:
 *      0 on success, -errno otherwise.
 */
int ata_std_softreset(struct ata_port *ap, int verbose, unsigned int *classes)
{
        unsigned int slave_possible = ap->flags & ATA_FLAG_SLAVE_POSS;
        unsigned int devmask = 0, err_mask;
        u8 err;

        DPRINTK("ENTER\n");

        if (ap->ops->scr_read && !sata_dev_present(ap)) {
                classes[0] = ATA_DEV_NONE;
                goto out;
        }

        /* determine if device 0/1 are present */
        if (ata_devchk(ap, 0))
                devmask |= (1 << 0);
        if (slave_possible && ata_devchk(ap, 1))
                devmask |= (1 << 1);

        /* select device 0 again */
        ap->ops->dev_select(ap, 0);

        /* issue bus reset */
        DPRINTK("about to softreset, devmask=%x\n", devmask);
        err_mask = ata_bus_softreset(ap, devmask);
        if (err_mask) {
                if (verbose)
                        printk(KERN_ERR "ata%u: SRST failed (err_mask=0x%x)\n",
                               ap->id, err_mask);
                else
                        DPRINTK("EXIT, softreset failed (err_mask=0x%x)\n",
                                err_mask);
                return -EIO;
        }

        /* determine by signature whether we have ATA or ATAPI devices */
        classes[0] = ata_dev_try_classify(ap, 0, &err);
        if (slave_possible && err != 0x81)
                classes[1] = ata_dev_try_classify(ap, 1, &err);

 out:
        DPRINTK("EXIT, classes[0]=%u [1]=%u\n", classes[0], classes[1]);
        return 0;
}

/**
 *      sata_std_hardreset - reset host port via SATA phy reset
 *      @ap: port to reset
 *      @verbose: fail verbosely
 *      @class: resulting class of attached device
 *
 *      SATA phy-reset host port using DET bits of SControl register.
 *      This function is to be used as standard callback for
 *      ata_drive_*_reset().
 *
 *      LOCKING:
 *      Kernel thread context (may sleep)
 *
 *      RETURNS:
 *      0 on success, -errno otherwise.
 */
int sata_std_hardreset(struct ata_port *ap, int verbose, unsigned int *class)
{
        DPRINTK("ENTER\n");

        /* Issue phy wake/reset */
        scr_write_flush(ap, SCR_CONTROL, 0x301);

        /*
         * Couldn't find anything in SATA I/II specs, but AHCI-1.1
         * 10.4.2 says at least 1 ms.
         */
        msleep(1);

        /* Bring phy back */
        sata_phy_resume(ap);

        /* TODO: phy layer with polling, timeouts, etc. */
        if (!sata_dev_present(ap)) {
                *class = ATA_DEV_NONE;
                DPRINTK("EXIT, link offline\n");
                return 0;
        }

        if (ata_busy_sleep(ap, ATA_TMOUT_BOOT_QUICK, ATA_TMOUT_BOOT)) {
                if (verbose)
                        printk(KERN_ERR "ata%u: COMRESET failed "
                               "(device not ready)\n", ap->id);
                else
                        DPRINTK("EXIT, device not ready\n");
                return -EIO;
        }

        ap->ops->dev_select(ap, 0);     /* probably unnecessary */

        *class = ata_dev_try_classify(ap, 0, NULL);

        DPRINTK("EXIT, class=%u\n", *class);
        return 0;
}

/**
 *      ata_std_postreset - standard postreset callback
 *      @ap: the target ata_port
 *      @classes: classes of attached devices
 *
 *      This function is invoked after a successful reset.  Note that
 *      the device might have been reset more than once using
 *      different reset methods before postreset is invoked.
 *
 *      This function is to be used as standard callback for
 *      ata_drive_*_reset().
 *
 *      LOCKING:
 *      Kernel thread context (may sleep)
 */
void ata_std_postreset(struct ata_port *ap, unsigned int *classes)
{
        DPRINTK("ENTER\n");

        /* set cable type if it isn't already set */
        if (ap->cbl == ATA_CBL_NONE && ap->flags & ATA_FLAG_SATA)
                ap->cbl = ATA_CBL_SATA;

        /* print link status */
        if (ap->cbl == ATA_CBL_SATA)
                sata_print_link_status(ap);

        /* re-enable interrupts */
        if (ap->ioaddr.ctl_addr)        /* FIXME: hack. create a hook instead */
                ata_irq_on(ap);

        /* is double-select really necessary? */
        if (classes[0] != ATA_DEV_NONE)
                ap->ops->dev_select(ap, 1);
        if (classes[1] != ATA_DEV_NONE)
                ap->ops->dev_select(ap, 0);

        /* bail out if no device is present */
        if (classes[0] == ATA_DEV_NONE && classes[1] == ATA_DEV_NONE) {
                DPRINTK("EXIT, no device\n");
                return;
        }

        /* set up device control */
        if (ap->ioaddr.ctl_addr) {
                if (ap->flags & ATA_FLAG_MMIO)
                        writeb(ap->ctl, (void __iomem *) ap->ioaddr.ctl_addr);
                else
                        outb(ap->ctl, ap->ioaddr.ctl_addr);
        }

        DPRINTK("EXIT\n");
}

/**
 *      ata_std_probe_reset - standard probe reset method
 *      @ap: prot to perform probe-reset
 *      @classes: resulting classes of attached devices
 *
 *      The stock off-the-shelf ->probe_reset method.
 *
 *      LOCKING:
 *      Kernel thread context (may sleep)
 *
 *      RETURNS:
 *      0 on success, -errno otherwise.
 */
int ata_std_probe_reset(struct ata_port *ap, unsigned int *classes)
{
        ata_reset_fn_t hardreset;

        hardreset = NULL;
        if (ap->flags & ATA_FLAG_SATA && ap->ops->scr_read)
                hardreset = sata_std_hardreset;

        return ata_drive_probe_reset(ap, ata_std_probeinit,
                                     ata_std_softreset, hardreset,
                                     ata_std_postreset, classes);
}

static int do_probe_reset(struct ata_port *ap, ata_reset_fn_t reset,
                          ata_postreset_fn_t postreset,
                          unsigned int *classes)
{
        int i, rc;

        for (i = 0; i < ATA_MAX_DEVICES; i++)
                classes[i] = ATA_DEV_UNKNOWN;

        rc = reset(ap, 0, classes);
        if (rc)
                return rc;

        /* If any class isn't ATA_DEV_UNKNOWN, consider classification
         * is complete and convert all ATA_DEV_UNKNOWN to
         * ATA_DEV_NONE.
         */
        for (i = 0; i < ATA_MAX_DEVICES; i++)
                if (classes[i] != ATA_DEV_UNKNOWN)
                        break;

        if (i < ATA_MAX_DEVICES)
                for (i = 0; i < ATA_MAX_DEVICES; i++)
                        if (classes[i] == ATA_DEV_UNKNOWN)
                                classes[i] = ATA_DEV_NONE;

        if (postreset)
                postreset(ap, classes);

        return classes[0] != ATA_DEV_UNKNOWN ? 0 : -ENODEV;
}

/**
 *      ata_drive_probe_reset - Perform probe reset with given methods
 *      @ap: port to reset
 *      @probeinit: probeinit method (can be NULL)
 *      @softreset: softreset method (can be NULL)
 *      @hardreset: hardreset method (can be NULL)
 *      @postreset: postreset method (can be NULL)
 *      @classes: resulting classes of attached devices
 *
 *      Reset the specified port and classify attached devices using
 *      given methods.  This function prefers softreset but tries all
 *      possible reset sequences to reset and classify devices.  This
 *      function is intended to be used for constructing ->probe_reset
 *      callback by low level drivers.
 *
 *      Reset methods should follow the following rules.
 *
 *      - Return 0 on sucess, -errno on failure.
 *      - If classification is supported, fill classes[] with
 *        recognized class codes.
 *      - If classification is not supported, leave classes[] alone.
 *      - If verbose is non-zero, print error message on failure;
 *        otherwise, shut up.
 *
 *      LOCKING:
 *      Kernel thread context (may sleep)
 *
 *      RETURNS:
 *      0 on success, -EINVAL if no reset method is avaliable, -ENODEV
 *      if classification fails, and any error code from reset
 *      methods.
 */
int ata_drive_probe_reset(struct ata_port *ap, ata_probeinit_fn_t probeinit,
                          ata_reset_fn_t softreset, ata_reset_fn_t hardreset,
                          ata_postreset_fn_t postreset, unsigned int *classes)
{
        int rc = -EINVAL;

        if (probeinit)
                probeinit(ap);

        if (softreset) {
                rc = do_probe_reset(ap, softreset, postreset, classes);
                if (rc == 0)
                        return 0;
        }

        if (!hardreset)
                return rc;

        rc = do_probe_reset(ap, hardreset, postreset, classes);
        if (rc == 0 || rc != -ENODEV)
                return rc;

        if (softreset)
                rc = do_probe_reset(ap, softreset, postreset, classes);

        return rc;
}

/**
 *      ata_dev_same_device - Determine whether new ID matches configured device
 *      @ap: port on which the device to compare against resides
 *      @dev: device to compare against
 *      @new_class: class of the new device
 *      @new_id: IDENTIFY page of the new device
 *
 *      Compare @new_class and @new_id against @dev and determine
 *      whether @dev is the device indicated by @new_class and
 *      @new_id.
 *
 *      LOCKING:
 *      None.
 *
 *      RETURNS:
 *      1 if @dev matches @new_class and @new_id, 0 otherwise.
 */
static int ata_dev_same_device(struct ata_port *ap, struct ata_device *dev,
                               unsigned int new_class, const u16 *new_id)
{
        const u16 *old_id = dev->id;
        unsigned char model[2][41], serial[2][21];
        u64 new_n_sectors;

        if (dev->class != new_class) {
                printk(KERN_INFO
                       "ata%u: dev %u class mismatch %d != %d\n",
                       ap->id, dev->devno, dev->class, new_class);
                return 0;
        }

        ata_id_c_string(old_id, model[0], ATA_ID_PROD_OFS, sizeof(model[0]));
        ata_id_c_string(new_id, model[1], ATA_ID_PROD_OFS, sizeof(model[1]));
        ata_id_c_string(old_id, serial[0], ATA_ID_SERNO_OFS, sizeof(serial[0]));
        ata_id_c_string(new_id, serial[1], ATA_ID_SERNO_OFS, sizeof(serial[1]));
        new_n_sectors = ata_id_n_sectors(new_id);

        if (strcmp(model[0], model[1])) {
                printk(KERN_INFO
                       "ata%u: dev %u model number mismatch '%s' != '%s'\n",
                       ap->id, dev->devno, model[0], model[1]);
                return 0;
        }

        if (strcmp(serial[0], serial[1])) {
                printk(KERN_INFO
                       "ata%u: dev %u serial number mismatch '%s' != '%s'\n",
                       ap->id, dev->devno, serial[0], serial[1]);
                return 0;
        }

        if (dev->class == ATA_DEV_ATA && dev->n_sectors != new_n_sectors) {
                printk(KERN_INFO
                       "ata%u: dev %u n_sectors mismatch %llu != %llu\n",
                       ap->id, dev->devno, (unsigned long long)dev->n_sectors,
                       (unsigned long long)new_n_sectors);
                return 0;
        }

        return 1;
}

/**
 *      ata_dev_revalidate - Revalidate ATA device
 *      @ap: port on which the device to revalidate resides
 *      @dev: device to revalidate
 *      @post_reset: is this revalidation after reset?
 *
 *      Re-read IDENTIFY page and make sure @dev is still attached to
 *      the port.
 *
 *      LOCKING:
 *      Kernel thread context (may sleep)
 *
 *      RETURNS:
 *      0 on success, negative errno otherwise
 */
int ata_dev_revalidate(struct ata_port *ap, struct ata_device *dev,
                       int post_reset)
{
        unsigned int class;
        u16 *id;
        int rc;

        if (!ata_dev_present(dev))
                return -ENODEV;

        class = dev->class;
        id = NULL;

        /* allocate & read ID data */
        rc = ata_dev_read_id(ap, dev, &class, post_reset, &id);
        if (rc)
                goto fail;

        /* is the device still there? */
        if (!ata_dev_same_device(ap, dev, class, id)) {
                rc = -ENODEV;
                goto fail;
        }

        kfree(dev->id);
        dev->id = id;

        /* configure device according to the new ID */
        return ata_dev_configure(ap, dev, 0);

 fail:
        printk(KERN_ERR "ata%u: dev %u revalidation failed (errno=%d)\n",
               ap->id, dev->devno, rc);
        kfree(id);
        return rc;
}

static void ata_pr_blacklisted(const struct ata_port *ap,
                               const struct ata_device *dev)
{
        printk(KERN_WARNING "ata%u: dev %u is on DMA blacklist, disabling DMA\n",
                ap->id, dev->devno);
}

static const char * const ata_dma_blacklist [] = {
        "WDC AC11000H",
        "WDC AC22100H",
        "WDC AC32500H",
        "WDC AC33100H",
        "WDC AC31600H",
        "WDC AC32100H",
        "WDC AC23200L",
        "Compaq CRD-8241B",
        "CRD-8400B",
        "CRD-8480B",
        "CRD-8482B",
        "CRD-84",
        "SanDisk SDP3B",
        "SanDisk SDP3B-64",
        "SANYO CD-ROM CRD",
        "HITACHI CDR-8",
        "HITACHI CDR-8335",
        "HITACHI CDR-8435",
        "Toshiba CD-ROM XM-6202B",
        "TOSHIBA CD-ROM XM-1702BC",
        "CD-532E-A",
        "E-IDE CD-ROM CR-840",
        "CD-ROM Drive/F5A",
        "WPI CDD-820",
        "SAMSUNG CD-ROM SC-148C",
        "SAMSUNG CD-ROM SC",
        "SanDisk SDP3B-64",
        "ATAPI CD-ROM DRIVE 40X MAXIMUM",
        "_NEC DV5800A",
};

static int ata_dma_blacklisted(const struct ata_device *dev)
{
        unsigned char model_num[41];
        int i;

        ata_id_c_string(dev->id, model_num, ATA_ID_PROD_OFS, sizeof(model_num));

        for (i = 0; i < ARRAY_SIZE(ata_dma_blacklist); i++)
                if (!strcmp(ata_dma_blacklist[i], model_num))
                        return 1;

        return 0;
}

static unsigned int ata_get_mode_mask(const struct ata_port *ap, int shift)
{
        const struct ata_device *master, *slave;
        unsigned int mask;

        master = &ap->device[0];
        slave = &ap->device[1];

        WARN_ON(!ata_dev_present(master) && !ata_dev_present(slave));

        if (shift == ATA_SHIFT_UDMA) {
                mask = ap->udma_mask;
                if (ata_dev_present(master)) {
                        mask &= (master->id[ATA_ID_UDMA_MODES] & 0xff);
                        if (ata_dma_blacklisted(master)) {
                                mask = 0;
                                ata_pr_blacklisted(ap, master);
                        }
                }
                if (ata_dev_present(slave)) {
                        mask &= (slave->id[ATA_ID_UDMA_MODES] & 0xff);
                        if (ata_dma_blacklisted(slave)) {
                                mask = 0;
                                ata_pr_blacklisted(ap, slave);
                        }
                }
        }
        else if (shift == ATA_SHIFT_MWDMA) {
                mask = ap->mwdma_mask;
                if (ata_dev_present(master)) {
                        mask &= (master->id[ATA_ID_MWDMA_MODES] & 0x07);
                        if (ata_dma_blacklisted(master)) {
                                mask = 0;
                                ata_pr_blacklisted(ap, master);
                        }
                }
                if (ata_dev_present(slave)) {
                        mask &= (slave->id[ATA_ID_MWDMA_MODES] & 0x07);
                        if (ata_dma_blacklisted(slave)) {
                                mask = 0;
                                ata_pr_blacklisted(ap, slave);
                        }
                }
        }
        else if (shift == ATA_SHIFT_PIO) {
                mask = ap->pio_mask;
                if (ata_dev_present(master)) {
                        /* spec doesn't return explicit support for
                         * PIO0-2, so we fake it
                         */
                        u16 tmp_mode = master->id[ATA_ID_PIO_MODES] & 0x03;
                        tmp_mode <<= 3;
                        tmp_mode |= 0x7;
                        mask &= tmp_mode;
                }
                if (ata_dev_present(slave)) {
                        /* spec doesn't return explicit support for
                         * PIO0-2, so we fake it
                         */
                        u16 tmp_mode = slave->id[ATA_ID_PIO_MODES] & 0x03;
                        tmp_mode <<= 3;
                        tmp_mode |= 0x7;
                        mask &= tmp_mode;
                }
        }
        else {
                mask = 0xffffffff; /* shut up compiler warning */
                BUG();
        }

        return mask;
}

/* find greatest bit */
static int fgb(u32 bitmap)
{
        unsigned int i;
        int x = -1;

        for (i = 0; i < 32; i++)
                if (bitmap & (1 << i))
                        x = i;

        return x;
}

/**
 *      ata_choose_xfer_mode - attempt to find best transfer mode
 *      @ap: Port for which an xfer mode will be selected
 *      @xfer_mode_out: (output) SET FEATURES - XFER MODE code
 *      @xfer_shift_out: (output) bit shift that selects this mode
 *
 *      Based on host and device capabilities, determine the
 *      maximum transfer mode that is amenable to all.
 *
 *      LOCKING:
 *      PCI/etc. bus probe sem.
 *
 *      RETURNS:
 *      Zero on success, negative on error.
 */

static int ata_choose_xfer_mode(const struct ata_port *ap,
                                u8 *xfer_mode_out,
                                unsigned int *xfer_shift_out)
{
        unsigned int mask, shift;
        int x, i;

        for (i = 0; i < ARRAY_SIZE(xfer_mode_classes); i++) {
                shift = xfer_mode_classes[i].shift;
                mask = ata_get_mode_mask(ap, shift);

                x = fgb(mask);
                if (x >= 0) {
                        *xfer_mode_out = xfer_mode_classes[i].base + x;
                        *xfer_shift_out = shift;
                        return 0;
                }
        }

        return -1;
}

/**
 *      ata_dev_set_xfermode - Issue SET FEATURES - XFER MODE command
 *      @ap: Port associated with device @dev
 *      @dev: Device to which command will be sent
 *
 *      Issue SET FEATURES - XFER MODE command to device @dev
 *      on port @ap.
 *
 *      LOCKING:
 *      PCI/etc. bus probe sem.
 */

static void ata_dev_set_xfermode(struct ata_port *ap, struct ata_device *dev)
{
        struct ata_taskfile tf;

        /* set up set-features taskfile */
        DPRINTK("set features - xfer mode\n");

        ata_tf_init(ap, &tf, dev->devno);
        tf.command = ATA_CMD_SET_FEATURES;
        tf.feature = SETFEATURES_XFER;
        tf.flags |= ATA_TFLAG_ISADDR | ATA_TFLAG_DEVICE;
        tf.protocol = ATA_PROT_NODATA;
        tf.nsect = dev->xfer_mode;

        if (ata_exec_internal(ap, dev, &tf, DMA_NONE, NULL, 0)) {
                printk(KERN_ERR "ata%u: failed to set xfermode, disabled\n",
                       ap->id);
                ata_port_disable(ap);
        }

        DPRINTK("EXIT\n");
}

/**
 *      ata_dev_init_params - Issue INIT DEV PARAMS command
 *      @ap: Port associated with device @dev
 *      @dev: Device to which command will be sent
 *
 *      LOCKING:
 *      Kernel thread context (may sleep)
 *
 *      RETURNS:
 *      0 on success, AC_ERR_* mask otherwise.
 */

static unsigned int ata_dev_init_params(struct ata_port *ap,
                                        struct ata_device *dev)
{
        struct ata_taskfile tf;
        unsigned int err_mask;
        u16 sectors = dev->id[6];
        u16 heads   = dev->id[3];

        /* Number of sectors per track 1-255. Number of heads 1-16 */
        if (sectors < 1 || sectors > 255 || heads < 1 || heads > 16)
                return 0;

        /* set up init dev params taskfile */
        DPRINTK("init dev params \n");

        ata_tf_init(ap, &tf, dev->devno);
        tf.command = ATA_CMD_INIT_DEV_PARAMS;
        tf.flags |= ATA_TFLAG_ISADDR | ATA_TFLAG_DEVICE;
        tf.protocol = ATA_PROT_NODATA;
        tf.nsect = sectors;
        tf.device |= (heads - 1) & 0x0f; /* max head = num. of heads - 1 */

        err_mask = ata_exec_internal(ap, dev, &tf, DMA_NONE, NULL, 0);

        DPRINTK("EXIT, err_mask=%x\n", err_mask);
        return err_mask;
}

/**
 *      ata_sg_clean - Unmap DMA memory associated with command
 *      @qc: Command containing DMA memory to be released
 *
 *      Unmap all mapped DMA memory associated with this command.
 *
 *      LOCKING:
 *      spin_lock_irqsave(host_set lock)
 */

static void ata_sg_clean(struct ata_queued_cmd *qc)
{
        struct ata_port *ap = qc->ap;
        struct scatterlist *sg = qc->__sg;
        int dir = qc->dma_dir;
        void *pad_buf = NULL;

        WARN_ON(!(qc->flags & ATA_QCFLAG_DMAMAP));
        WARN_ON(sg == NULL);

        if (qc->flags & ATA_QCFLAG_SINGLE)
                WARN_ON(qc->n_elem > 1);

        VPRINTK("unmapping %u sg elements\n", qc->n_elem);

        /* if we padded the buffer out to 32-bit bound, and data
         * xfer direction is from-device, we must copy from the
         * pad buffer back into the supplied buffer
         */
        if (qc->pad_len && !(qc->tf.flags & ATA_TFLAG_WRITE))
                pad_buf = ap->pad + (qc->tag * ATA_DMA_PAD_SZ);

        if (qc->flags & ATA_QCFLAG_SG) {
                if (qc->n_elem)
                        dma_unmap_sg(ap->host_set->dev, sg, qc->n_elem, dir);
                /* restore last sg */
                sg[qc->orig_n_elem - 1].length += qc->pad_len;
                if (pad_buf) {
                        struct scatterlist *psg = &qc->pad_sgent;
                        void *addr = kmap_atomic(psg->page, KM_IRQ0);
                        memcpy(addr + psg->offset, pad_buf, qc->pad_len);
                        kunmap_atomic(addr, KM_IRQ0);
                }
        } else {
                if (qc->n_elem)
                        dma_unmap_single(ap->host_set->dev,
                                sg_dma_address(&sg[0]), sg_dma_len(&sg[0]),
                                dir);
                /* restore sg */
                sg->length += qc->pad_len;
                if (pad_buf)
                        memcpy(qc->buf_virt + sg->length - qc->pad_len,
                               pad_buf, qc->pad_len);
        }

        qc->flags &= ~ATA_QCFLAG_DMAMAP;
        qc->__sg = NULL;
}

/**
 *      ata_fill_sg - Fill PCI IDE PRD table
 *      @qc: Metadata associated with taskfile to be transferred
 *
 *      Fill PCI IDE PRD (scatter-gather) table with segments
 *      associated with the current disk command.
 *
 *      LOCKING:
 *      spin_lock_irqsave(host_set lock)
 *
 */
static void ata_fill_sg(struct ata_queued_cmd *qc)
{
        struct ata_port *ap = qc->ap;
        struct scatterlist *sg;
        unsigned int idx;

        WARN_ON(qc->__sg == NULL);
        WARN_ON(qc->n_elem == 0 && qc->pad_len == 0);

        idx = 0;
        ata_for_each_sg(sg, qc) {
                u32 addr, offset;
                u32 sg_len, len;

                /* determine if physical DMA addr spans 64K boundary.
                 * Note h/w doesn't support 64-bit, so we unconditionally
                 * truncate dma_addr_t to u32.
                 */
                addr = (u32) sg_dma_address(sg);
                sg_len = sg_dma_len(sg);

                while (sg_len) {
                        offset = addr & 0xffff;
                        len = sg_len;
                        if ((offset + sg_len) > 0x10000)
                                len = 0x10000 - offset;

                        ap->prd[idx].addr = cpu_to_le32(addr);
                        ap->prd[idx].flags_len = cpu_to_le32(len & 0xffff);
                        VPRINTK("PRD[%u] = (0x%X, 0x%X)\n", idx, addr, len);

                        idx++;
                        sg_len -= len;
                        addr += len;
                }
        }

        if (idx)
                ap->prd[idx - 1].flags_len |= cpu_to_le32(ATA_PRD_EOT);
}
/**
 *      ata_check_atapi_dma - Check whether ATAPI DMA can be supported
 *      @qc: Metadata associated with taskfile to check
 *
 *      Allow low-level driver to filter ATA PACKET commands, returning
 *      a status indicating whether or not it is OK to use DMA for the
 *      supplied PACKET command.
 *
 *      LOCKING:
 *      spin_lock_irqsave(host_set lock)
 *
 *      RETURNS: 0 when ATAPI DMA can be used
 *               nonzero otherwise
 */
int ata_check_atapi_dma(struct ata_queued_cmd *qc)
{
        struct ata_port *ap = qc->ap;
        int rc = 0; /* Assume ATAPI DMA is OK by default */

        if (ap->ops->check_atapi_dma)
                rc = ap->ops->check_atapi_dma(qc);

        return rc;
}
/**
 *      ata_qc_prep - Prepare taskfile for submission
 *      @qc: Metadata associated with taskfile to be prepared
 *
 *      Prepare ATA taskfile for submission.
 *
 *      LOCKING:
 *      spin_lock_irqsave(host_set lock)
 */
void ata_qc_prep(struct ata_queued_cmd *qc)
{
        if (!(qc->flags & ATA_QCFLAG_DMAMAP))
                return;

        ata_fill_sg(qc);
}

/**
 *      ata_sg_init_one - Associate command with memory buffer
 *      @qc: Command to be associated
 *      @buf: Memory buffer
 *      @buflen: Length of memory buffer, in bytes.
 *
 *      Initialize the data-related elements of queued_cmd @qc
 *      to point to a single memory buffer, @buf of byte length @buflen.
 *
 *      LOCKING:
 *      spin_lock_irqsave(host_set lock)
 */

void ata_sg_init_one(struct ata_queued_cmd *qc, void *buf, unsigned int buflen)
{
        struct scatterlist *sg;

        qc->flags |= ATA_QCFLAG_SINGLE;

        memset(&qc->sgent, 0, sizeof(qc->sgent));
        qc->__sg = &qc->sgent;
        qc->n_elem = 1;
        qc->orig_n_elem = 1;
        qc->buf_virt = buf;

        sg = qc->__sg;
        sg_init_one(sg, buf, buflen);
}

/**
 *      ata_sg_init - Associate command with scatter-gather table.
 *      @qc: Command to be associated
 *      @sg: Scatter-gather table.
 *      @n_elem: Number of elements in s/g table.
 *
 *      Initialize the data-related elements of queued_cmd @qc
 *      to point to a scatter-gather table @sg, containing @n_elem
 *      elements.
 *
 *      LOCKING:
 *      spin_lock_irqsave(host_set lock)
 */

void ata_sg_init(struct ata_queued_cmd *qc, struct scatterlist *sg,
                 unsigned int n_elem)
{
        qc->flags |= ATA_QCFLAG_SG;
        qc->__sg = sg;
        qc->n_elem = n_elem;
        qc->orig_n_elem = n_elem;
}

/**
 *      ata_sg_setup_one - DMA-map the memory buffer associated with a command.
 *      @qc: Command with memory buffer to be mapped.
 *
 *      DMA-map the memory buffer associated with queued_cmd @qc.
 *
 *      LOCKING:
 *      spin_lock_irqsave(host_set lock)
 *
 *      RETURNS:
 *      Zero on success, negative on error.
 */

static int ata_sg_setup_one(struct ata_queued_cmd *qc)
{
        struct ata_port *ap = qc->ap;
        int dir = qc->dma_dir;
        struct scatterlist *sg = qc->__sg;
        dma_addr_t dma_address;
        int trim_sg = 0;

        /* we must lengthen transfers to end on a 32-bit boundary */
        qc->pad_len = sg->length & 3;
        if (qc->pad_len) {
                void *pad_buf = ap->pad + (qc->tag * ATA_DMA_PAD_SZ);
                struct scatterlist *psg = &qc->pad_sgent;

                WARN_ON(qc->dev->class != ATA_DEV_ATAPI);

                memset(pad_buf, 0, ATA_DMA_PAD_SZ);

                if (qc->tf.flags & ATA_TFLAG_WRITE)
                        memcpy(pad_buf, qc->buf_virt + sg->length - qc->pad_len,
                               qc->pad_len);

                sg_dma_address(psg) = ap->pad_dma + (qc->tag * ATA_DMA_PAD_SZ);
                sg_dma_len(psg) = ATA_DMA_PAD_SZ;
                /* trim sg */
                sg->length -= qc->pad_len;
                if (sg->length == 0)
                        trim_sg = 1;

                DPRINTK("padding done, sg->length=%u pad_len=%u\n",
                        sg->length, qc->pad_len);
        }

        if (trim_sg) {
                qc->n_elem--;
                goto skip_map;
        }

        dma_address = dma_map_single(ap->host_set->dev, qc->buf_virt,
                                     sg->length, dir);
        if (dma_mapping_error(dma_address)) {
                /* restore sg */
                sg->length += qc->pad_len;
                return -1;
        }

        sg_dma_address(sg) = dma_address;
        sg_dma_len(sg) = sg->length;

skip_map:
        DPRINTK("mapped buffer of %d bytes for %s\n", sg_dma_len(sg),
                qc->tf.flags & ATA_TFLAG_WRITE ? "write" : "read");

        return 0;
}

/**
 *      ata_sg_setup - DMA-map the scatter-gather table associated with a command.
 *      @qc: Command with scatter-gather table to be mapped.
 *
 *      DMA-map the scatter-gather table associated with queued_cmd @qc.
 *
 *      LOCKING:
 *      spin_lock_irqsave(host_set lock)
 *
 *      RETURNS:
 *      Zero on success, negative on error.
 *
 */

static int ata_sg_setup(struct ata_queued_cmd *qc)
{
        struct ata_port *ap = qc->ap;
        struct scatterlist *sg = qc->__sg;
        struct scatterlist *lsg = &sg[qc->n_elem - 1];
        int n_elem, pre_n_elem, dir, trim_sg = 0;

        VPRINTK("ENTER, ata%u\n", ap->id);
        WARN_ON(!(qc->flags & ATA_QCFLAG_SG));

        /* we must lengthen transfers to end on a 32-bit boundary */
        qc->pad_len = lsg->length & 3;
        if (qc->pad_len) {
                void *pad_buf = ap->pad + (qc->tag * ATA_DMA_PAD_SZ);
                struct scatterlist *psg = &qc->pad_sgent;
                unsigned int offset;

                WARN_ON(qc->dev->class != ATA_DEV_ATAPI);

                memset(pad_buf, 0, ATA_DMA_PAD_SZ);

                /*
                 * psg->page/offset are used to copy to-be-written
                 * data in this function or read data in ata_sg_clean.
                 */
                offset = lsg->offset + lsg->length - qc->pad_len;
                psg->page = nth_page(lsg->page, offset >> PAGE_SHIFT);
                psg->offset = offset_in_page(offset);

                if (qc->tf.flags & ATA_TFLAG_WRITE) {
                        void *addr = kmap_atomic(psg->page, KM_IRQ0);
                        memcpy(pad_buf, addr + psg->offset, qc->pad_len);
                        kunmap_atomic(addr, KM_IRQ0);
                }

                sg_dma_address(psg) = ap->pad_dma + (qc->tag * ATA_DMA_PAD_SZ);
                sg_dma_len(psg) = ATA_DMA_PAD_SZ;
                /* trim last sg */
                lsg->length -= qc->pad_len;
                if (lsg->length == 0)
                        trim_sg = 1;

                DPRINTK("padding done, sg[%d].length=%u pad_len=%u\n",
                        qc->n_elem - 1, lsg->length, qc->pad_len);
        }

        pre_n_elem = qc->n_elem;
        if (trim_sg && pre_n_elem)
                pre_n_elem--;

        if (!pre_n_elem) {
                n_elem = 0;
                goto skip_map;
        }

        dir = qc->dma_dir;
        n_elem = dma_map_sg(ap->host_set->dev, sg, pre_n_elem, dir);
        if (n_elem < 1) {
                /* restore last sg */
                lsg->length += qc->pad_len;
                return -1;
        }

        DPRINTK("%d sg elements mapped\n", n_elem);

skip_map:
        qc->n_elem = n_elem;

        return 0;
}

/**
 *      ata_poll_qc_complete - turn irq back on and finish qc
 *      @qc: Command to complete
 *      @err_mask: ATA status register content
 *
 *      LOCKING:
 *      None.  (grabs host lock)
 */

void ata_poll_qc_complete(struct ata_queued_cmd *qc)
{
        struct ata_port *ap = qc->ap;
        unsigned long flags;

        spin_lock_irqsave(&ap->host_set->lock, flags);
        ap->flags &= ~ATA_FLAG_NOINTR;
        ata_irq_on(ap);
        ata_qc_complete(qc);
        spin_unlock_irqrestore(&ap->host_set->lock, flags);
}

/**
 *      ata_pio_poll - poll using PIO, depending on current state
 *      @ap: the target ata_port
 *
 *      LOCKING:
 *      None.  (executing in kernel thread context)
 *
 *      RETURNS:
 *      timeout value to use
 */

static unsigned long ata_pio_poll(struct ata_port *ap)
{
        struct ata_queued_cmd *qc;
        u8 status;
        unsigned int poll_state = HSM_ST_UNKNOWN;
        unsigned int reg_state = HSM_ST_UNKNOWN;

        qc = ata_qc_from_tag(ap, ap->active_tag);
        WARN_ON(qc == NULL);

        switch (ap->hsm_task_state) {
        case HSM_ST:
        case HSM_ST_POLL:
                poll_state = HSM_ST_POLL;
                reg_state = HSM_ST;
                break;
        case HSM_ST_LAST:
        case HSM_ST_LAST_POLL:
                poll_state = HSM_ST_LAST_POLL;
                reg_state = HSM_ST_LAST;
                break;
        default:
                BUG();
                break;
        }

        status = ata_chk_status(ap);
        if (status & ATA_BUSY) {
                if (time_after(jiffies, ap->pio_task_timeout)) {
                        qc->err_mask |= AC_ERR_TIMEOUT;
                        ap->hsm_task_state = HSM_ST_TMOUT;
                        return 0;
                }
                ap->hsm_task_state = poll_state;
                return ATA_SHORT_PAUSE;
        }

        ap->hsm_task_state = reg_state;
        return 0;
}

/**
 *      ata_pio_complete - check if drive is busy or idle
 *      @ap: the target ata_port
 *
 *      LOCKING:
 *      None.  (executing in kernel thread context)
 *
 *      RETURNS:
 *      Non-zero if qc completed, zero otherwise.
 */

static int ata_pio_complete (struct ata_port *ap)
{
        struct ata_queued_cmd *qc;
        u8 drv_stat;

        /*
         * This is purely heuristic.  This is a fast path.  Sometimes when
         * we enter, BSY will be cleared in a chk-status or two.  If not,
         * the drive is probably seeking or something.  Snooze for a couple
         * msecs, then chk-status again.  If still busy, fall back to
         * HSM_ST_POLL state.
         */
        drv_stat = ata_busy_wait(ap, ATA_BUSY, 10);
        if (drv_stat & ATA_BUSY) {
                msleep(2);
                drv_stat = ata_busy_wait(ap, ATA_BUSY, 10);
                if (drv_stat & ATA_BUSY) {
                        ap->hsm_task_state = HSM_ST_LAST_POLL;
                        ap->pio_task_timeout = jiffies + ATA_TMOUT_PIO;
                        return 0;
                }
        }

        qc = ata_qc_from_tag(ap, ap->active_tag);
        WARN_ON(qc == NULL);

        drv_stat = ata_wait_idle(ap);
        if (!ata_ok(drv_stat)) {
                qc->err_mask |= __ac_err_mask(drv_stat);
                ap->hsm_task_state = HSM_ST_ERR;
                return 0;
        }

        ap->hsm_task_state = HSM_ST_IDLE;

        WARN_ON(qc->err_mask);
        ata_poll_qc_complete(qc);

        /* another command may start at this point */

        return 1;
}


/**
 *      swap_buf_le16 - swap halves of 16-bit words in place
 *      @buf:  Buffer to swap
 *      @buf_words:  Number of 16-bit words in buffer.
 *
 *      Swap halves of 16-bit words if needed to convert from
 *      little-endian byte order to native cpu byte order, or
 *      vice-versa.
 *
 *      LOCKING:
 *      Inherited from caller.
 */
void swap_buf_le16(u16 *buf, unsigned int buf_words)
{
#ifdef __BIG_ENDIAN
        unsigned int i;

        for (i = 0; i < buf_words; i++)
                buf[i] = le16_to_cpu(buf[i]);
#endif /* __BIG_ENDIAN */
}

/**
 *      ata_mmio_data_xfer - Transfer data by MMIO
 *      @ap: port to read/write
 *      @buf: data buffer
 *      @buflen: buffer length
 *      @write_data: read/write
 *
 *      Transfer data from/to the device data register by MMIO.
 *
 *      LOCKING:
 *      Inherited from caller.
 */

static void ata_mmio_data_xfer(struct ata_port *ap, unsigned char *buf,
                               unsigned int buflen, int write_data)
{
        unsigned int i;
        unsigned int words = buflen >> 1;
        u16 *buf16 = (u16 *) buf;
        void __iomem *mmio = (void __iomem *)ap->ioaddr.data_addr;

        /* Transfer multiple of 2 bytes */
        if (write_data) {
                for (i = 0; i < words; i++)
                        writew(le16_to_cpu(buf16[i]), mmio);
        } else {
                for (i = 0; i < words; i++)
                        buf16[i] = cpu_to_le16(readw(mmio));
        }

        /* Transfer trailing 1 byte, if any. */
        if (unlikely(buflen & 0x01)) {
                u16 align_buf[1] = { 0 };
                unsigned char *trailing_buf = buf + buflen - 1;

                if (write_data) {
                        memcpy(align_buf, trailing_buf, 1);
                        writew(le16_to_cpu(align_buf[0]), mmio);
                } else {
                        align_buf[0] = cpu_to_le16(readw(mmio));
                        memcpy(trailing_buf, align_buf, 1);
                }
        }
}

/**
 *      ata_pio_data_xfer - Transfer data by PIO
 *      @ap: port to read/write
 *      @buf: data buffer
 *      @buflen: buffer length
 *      @write_data: read/write
 *
 *      Transfer data from/to the device data register by PIO.
 *
 *      LOCKING:
 *      Inherited from caller.
 */

static void ata_pio_data_xfer(struct ata_port *ap, unsigned char *buf,
                              unsigned int buflen, int write_data)
{
        unsigned int words = buflen >> 1;

        /* Transfer multiple of 2 bytes */
        if (write_data)
                outsw(ap->ioaddr.data_addr, buf, words);
        else
                insw(ap->ioaddr.data_addr, buf, words);

        /* Transfer trailing 1 byte, if any. */
        if (unlikely(buflen & 0x01)) {
                u16 align_buf[1] = { 0 };
                unsigned char *trailing_buf = buf + buflen - 1;

                if (write_data) {
                        memcpy(align_buf, trailing_buf, 1);
                        outw(le16_to_cpu(align_buf[0]), ap->ioaddr.data_addr);
                } else {
                        align_buf[0] = cpu_to_le16(inw(ap->ioaddr.data_addr));
                        memcpy(trailing_buf, align_buf, 1);
                }
        }
}

/**
 *      ata_data_xfer - Transfer data from/to the data register.
 *      @ap: port to read/write
 *      @buf: data buffer
 *      @buflen: buffer length
 *      @do_write: read/write
 *
 *      Transfer data from/to the device data register.
 *
 *      LOCKING:
 *      Inherited from caller.
 */

static void ata_data_xfer(struct ata_port *ap, unsigned char *buf,
                          unsigned int buflen, int do_write)
{
        /* Make the crap hardware pay the costs not the good stuff */
        if (unlikely(ap->flags & ATA_FLAG_IRQ_MASK)) {
                unsigned long flags;
                local_irq_save(flags);
                if (ap->flags & ATA_FLAG_MMIO)
                        ata_mmio_data_xfer(ap, buf, buflen, do_write);
                else
                        ata_pio_data_xfer(ap, buf, buflen, do_write);
                local_irq_restore(flags);
        } else {
                if (ap->flags & ATA_FLAG_MMIO)
                        ata_mmio_data_xfer(ap, buf, buflen, do_write);
                else
                        ata_pio_data_xfer(ap, buf, buflen, do_write);
        }
}

/**
 *      ata_pio_sector - Transfer ATA_SECT_SIZE (512 bytes) of data.
 *      @qc: Command on going
 *
 *      Transfer ATA_SECT_SIZE of data from/to the ATA device.
 *
 *      LOCKING:
 *      Inherited from caller.
 */

static void ata_pio_sector(struct ata_queued_cmd *qc)
{
        int do_write = (qc->tf.flags & ATA_TFLAG_WRITE);
        struct scatterlist *sg = qc->__sg;
        struct ata_port *ap = qc->ap;
        struct page *page;
        unsigned int offset;
        unsigned char *buf;

        if (qc->cursect == (qc->nsect - 1))
                ap->hsm_task_state = HSM_ST_LAST;

        page = sg[qc->cursg].page;
        offset = sg[qc->cursg].offset + qc->cursg_ofs * ATA_SECT_SIZE;

        /* get the current page and offset */
        page = nth_page(page, (offset >> PAGE_SHIFT));
        offset %= PAGE_SIZE;

        buf = kmap(page) + offset;

        qc->cursect++;
        qc->cursg_ofs++;

        if ((qc->cursg_ofs * ATA_SECT_SIZE) == (&sg[qc->cursg])->length) {
                qc->cursg++;
                qc->cursg_ofs = 0;
        }

        DPRINTK("data %s\n", qc->tf.flags & ATA_TFLAG_WRITE ? "write" : "read");

        /* do the actual data transfer */
        do_write = (qc->tf.flags & ATA_TFLAG_WRITE);
        ata_data_xfer(ap, buf, ATA_SECT_SIZE, do_write);

        kunmap(page);
}

/**
 *      __atapi_pio_bytes - Transfer data from/to the ATAPI device.
 *      @qc: Command on going
 *      @bytes: number of bytes
 *
 *      Transfer Transfer data from/to the ATAPI device.
 *
 *      LOCKING:
 *      Inherited from caller.
 *
 */

static void __atapi_pio_bytes(struct ata_queued_cmd *qc, unsigned int bytes)
{
        int do_write = (qc->tf.flags & ATA_TFLAG_WRITE);
        struct scatterlist *sg = qc->__sg;
        struct ata_port *ap = qc->ap;
        struct page *page;
        unsigned char *buf;
        unsigned int offset, count;

        if (qc->curbytes + bytes >= qc->nbytes)
                ap->hsm_task_state = HSM_ST_LAST;

next_sg:
        if (unlikely(qc->cursg >= qc->n_elem)) {
                /*
                 * The end of qc->sg is reached and the device expects
                 * more data to transfer. In order not to overrun qc->sg
                 * and fulfill length specified in the byte count register,
                 *    - for read case, discard trailing data from the device
                 *    - for write case, padding zero data to the device
                 */
                u16 pad_buf[1] = { 0 };
                unsigned int words = bytes >> 1;
                unsigned int i;

                if (words) /* warning if bytes > 1 */
                        printk(KERN_WARNING "ata%u: %u bytes trailing data\n",
                               ap->id, bytes);

                for (i = 0; i < words; i++)
                        ata_data_xfer(ap, (unsigned char*)pad_buf, 2, do_write);

                ap->hsm_task_state = HSM_ST_LAST;
                return;
        }

        sg = &qc->__sg[qc->cursg];

        page = sg->page;
        offset = sg->offset + qc->cursg_ofs;

        /* get the current page and offset */
        page = nth_page(page, (offset >> PAGE_SHIFT));
        offset %= PAGE_SIZE;

        /* don't overrun current sg */
        count = min(sg->length - qc->cursg_ofs, bytes);

        /* don't cross page boundaries */
        count = min(count, (unsigned int)PAGE_SIZE - offset);

        buf = kmap(page) + offset;

        bytes -= count;
        qc->curbytes += count;
        qc->cursg_ofs += count;

        if (qc->cursg_ofs == sg->length) {
                qc->cursg++;
                qc->cursg_ofs = 0;
        }

        DPRINTK("data %s\n", qc->tf.flags & ATA_TFLAG_WRITE ? "write" : "read");

        /* do the actual data transfer */
        ata_data_xfer(ap, buf, count, do_write);

        kunmap(page);

        if (bytes)
                goto next_sg;
}

/**
 *      atapi_pio_bytes - Transfer data from/to the ATAPI device.
 *      @qc: Command on going
 *
 *      Transfer Transfer data from/to the ATAPI device.
 *
 *      LOCKING:
 *      Inherited from caller.
 */

static void atapi_pio_bytes(struct ata_queued_cmd *qc)
{
        struct ata_port *ap = qc->ap;
        struct ata_device *dev = qc->dev;
        unsigned int ireason, bc_lo, bc_hi, bytes;
        int i_write, do_write = (qc->tf.flags & ATA_TFLAG_WRITE) ? 1 : 0;

        ap->ops->tf_read(ap, &qc->tf);
        ireason = qc->tf.nsect;
        bc_lo = qc->tf.lbam;
        bc_hi = qc->tf.lbah;
        bytes = (bc_hi << 8) | bc_lo;

        /* shall be cleared to zero, indicating xfer of data */
        if (ireason & (1 << 0))
                goto err_out;

        /* make sure transfer direction matches expected */
        i_write = ((ireason & (1 << 1)) == 0) ? 1 : 0;
        if (do_write != i_write)
                goto err_out;

        __atapi_pio_bytes(qc, bytes);

        return;

err_out:
        printk(KERN_INFO "ata%u: dev %u: ATAPI check failed\n",
              ap->id, dev->devno);
        qc->err_mask |= AC_ERR_HSM;
        ap->hsm_task_state = HSM_ST_ERR;
}

/**
 *      ata_pio_block - start PIO on a block
 *      @ap: the target ata_port
 *
 *      LOCKING:
 *      None.  (executing in kernel thread context)
 */

static void ata_pio_block(struct ata_port *ap)
{
        struct ata_queued_cmd *qc;
        u8 status;

        /*
         * This is purely heuristic.  This is a fast path.
         * Sometimes when we enter, BSY will be cleared in
         * a chk-status or two.  If not, the drive is probably seeking
         * or something.  Snooze for a couple msecs, then
         * chk-status again.  If still busy, fall back to
         * HSM_ST_POLL state.
         */
        status = ata_busy_wait(ap, ATA_BUSY, 5);
        if (status & ATA_BUSY) {
                msleep(2);
                status = ata_busy_wait(ap, ATA_BUSY, 10);
                if (status & ATA_BUSY) {
                        ap->hsm_task_state = HSM_ST_POLL;
                        ap->pio_task_timeout = jiffies + ATA_TMOUT_PIO;
                        return;
                }
        }

        qc = ata_qc_from_tag(ap, ap->active_tag);
        WARN_ON(qc == NULL);

        /* check error */
        if (status & (ATA_ERR | ATA_DF)) {
                qc->err_mask |= AC_ERR_DEV;
                ap->hsm_task_state = HSM_ST_ERR;
                return;
        }

        /* transfer data if any */
        if (is_atapi_taskfile(&qc->tf)) {
                /* DRQ=0 means no more data to transfer */
                if ((status & ATA_DRQ) == 0) {
                        ap->hsm_task_state = HSM_ST_LAST;
                        return;
                }

                atapi_pio_bytes(qc);
        } else {
                /* handle BSY=0, DRQ=0 as error */
                if ((status & ATA_DRQ) == 0) {
                        qc->err_mask |= AC_ERR_HSM;
                        ap->hsm_task_state = HSM_ST_ERR;
                        return;
                }

                ata_pio_sector(qc);
        }
}

static void ata_pio_error(struct ata_port *ap)
{
        struct ata_queued_cmd *qc;

        qc = ata_qc_from_tag(ap, ap->active_tag);
        WARN_ON(qc == NULL);

        if (qc->tf.command != ATA_CMD_PACKET)
                printk(KERN_WARNING "ata%u: PIO error\n", ap->id);

        /* make sure qc->err_mask is available to 
         * know what's wrong and recover
         */
        WARN_ON(qc->err_mask == 0);

        ap->hsm_task_state = HSM_ST_IDLE;

        ata_poll_qc_complete(qc);
}

static void ata_pio_task(void *_data)
{
        struct ata_port *ap = _data;
        unsigned long timeout;
        int qc_completed;

fsm_start:
        timeout = 0;
        qc_completed = 0;

        switch (ap->hsm_task_state) {
        case HSM_ST_IDLE:
                return;

        case HSM_ST:
                ata_pio_block(ap);
                break;

        case HSM_ST_LAST:
                qc_completed = ata_pio_complete(ap);
                break;

        case HSM_ST_POLL:
        case HSM_ST_LAST_POLL:
                timeout = ata_pio_poll(ap);
                break;

        case HSM_ST_TMOUT:
        case HSM_ST_ERR:
                ata_pio_error(ap);
                return;
        }

        if (timeout)
                ata_port_queue_task(ap, ata_pio_task, ap, timeout);
        else if (!qc_completed)
                goto fsm_start;
}

/**
 *      atapi_packet_task - Write CDB bytes to hardware
 *      @_data: Port to which ATAPI device is attached.
 *
 *      When device has indicated its readiness to accept
 *      a CDB, this function is called.  Send the CDB.
 *      If DMA is to be performed, exit immediately.
 *      Otherwise, we are in polling mode, so poll
 *      status under operation succeeds or fails.
 *
 *      LOCKING:
 *      Kernel thread context (may sleep)
 */

static void atapi_packet_task(void *_data)
{
        struct ata_port *ap = _data;
        struct ata_queued_cmd *qc;
        u8 status;

        qc = ata_qc_from_tag(ap, ap->active_tag);
        WARN_ON(qc == NULL);
        WARN_ON(!(qc->flags & ATA_QCFLAG_ACTIVE));

        /* sleep-wait for BSY to clear */
        DPRINTK("busy wait\n");
        if (ata_busy_sleep(ap, ATA_TMOUT_CDB_QUICK, ATA_TMOUT_CDB)) {
                qc->err_mask |= AC_ERR_TIMEOUT;
                goto err_out;
        }

        /* make sure DRQ is set */
        status = ata_chk_status(ap);
        if ((status & (ATA_BUSY | ATA_DRQ)) != ATA_DRQ) {
                qc->err_mask |= AC_ERR_HSM;
                goto err_out;
        }

        /* send SCSI cdb */
        DPRINTK("send cdb\n");
        WARN_ON(qc->dev->cdb_len < 12);

        if (qc->tf.protocol == ATA_PROT_ATAPI_DMA ||
            qc->tf.protocol == ATA_PROT_ATAPI_NODATA) {
                unsigned long flags;

                /* Once we're done issuing command and kicking bmdma,
                 * irq handler takes over.  To not lose irq, we need
                 * to clear NOINTR flag before sending cdb, but
                 * interrupt handler shouldn't be invoked before we're
                 * finished.  Hence, the following locking.
                 */
                spin_lock_irqsave(&ap->host_set->lock, flags);
                ap->flags &= ~ATA_FLAG_NOINTR;
                ata_data_xfer(ap, qc->cdb, qc->dev->cdb_len, 1);
                if (qc->tf.protocol == ATA_PROT_ATAPI_DMA)
                        ap->ops->bmdma_start(qc);       /* initiate bmdma */
                spin_unlock_irqrestore(&ap->host_set->lock, flags);
        } else {
                ata_data_xfer(ap, qc->cdb, qc->dev->cdb_len, 1);

                /* PIO commands are handled by polling */
                ap->hsm_task_state = HSM_ST;
                ata_port_queue_task(ap, ata_pio_task, ap, 0);
        }

        return;

err_out:
        ata_poll_qc_complete(qc);
}

/**
 *      ata_qc_timeout - Handle timeout of queued command
 *      @qc: Command that timed out
 *
 *      Some part of the kernel (currently, only the SCSI layer)
 *      has noticed that the active command on port @ap has not
 *      completed after a specified length of time.  Handle this
 *      condition by disabling DMA (if necessary) and completing
 *      transactions, with error if necessary.
 *
 *      This also handles the case of the "lost interrupt", where
 *      for some reason (possibly hardware bug, possibly driver bug)
 *      an interrupt was not delivered to the driver, even though the
 *      transaction completed successfully.
 *
 *      LOCKING:
 *      Inherited from SCSI layer (none, can sleep)
 */

static void ata_qc_timeout(struct ata_queued_cmd *qc)
{
        struct ata_port *ap = qc->ap;
        struct ata_host_set *host_set = ap->host_set;
        u8 host_stat = 0, drv_stat;
        unsigned long flags;

        DPRINTK("ENTER\n");

        ap->hsm_task_state = HSM_ST_IDLE;

        spin_lock_irqsave(&host_set->lock, flags);

        switch (qc->tf.protocol) {

        case ATA_PROT_DMA:
        case ATA_PROT_ATAPI_DMA:
                host_stat = ap->ops->bmdma_status(ap);

                /* before we do anything else, clear DMA-Start bit */
                ap->ops->bmdma_stop(qc);

                /* fall through */

        default:
                ata_altstatus(ap);
                drv_stat = ata_chk_status(ap);

                /* ack bmdma irq events */
                ap->ops->irq_clear(ap);

                printk(KERN_ERR "ata%u: command 0x%x timeout, stat 0x%x host_stat 0x%x\n",
                       ap->id, qc->tf.command, drv_stat, host_stat);

                /* complete taskfile transaction */
                qc->err_mask |= ac_err_mask(drv_stat);
                break;
        }

        spin_unlock_irqrestore(&host_set->lock, flags);

        ata_eh_qc_complete(qc);

        DPRINTK("EXIT\n");
}

/**
 *      ata_eng_timeout - Handle timeout of queued command
 *      @ap: Port on which timed-out command is active
 *
 *      Some part of the kernel (currently, only the SCSI layer)
 *      has noticed that the active command on port @ap has not
 *      completed after a specified length of time.  Handle this
 *      condition by disabling DMA (if necessary) and completing
 *      transactions, with error if necessary.
 *
 *      This also handles the case of the "lost interrupt", where
 *      for some reason (possibly hardware bug, possibly driver bug)
 *      an interrupt was not delivered to the driver, even though the
 *      transaction completed successfully.
 *
 *      LOCKING:
 *      Inherited from SCSI layer (none, can sleep)
 */

void ata_eng_timeout(struct ata_port *ap)
{
        DPRINTK("ENTER\n");

        ata_qc_timeout(ata_qc_from_tag(ap, ap->active_tag));

        DPRINTK("EXIT\n");
}

/**
 *      ata_qc_new - Request an available ATA command, for queueing
 *      @ap: Port associated with device @dev
 *      @dev: Device from whom we request an available command structure
 *
 *      LOCKING:
 *      None.
 */

static struct ata_queued_cmd *ata_qc_new(struct ata_port *ap)
{
        struct ata_queued_cmd *qc = NULL;
        unsigned int i;

        for (i = 0; i < ATA_MAX_QUEUE; i++)
                if (!test_and_set_bit(i, &ap->qactive)) {
                        qc = ata_qc_from_tag(ap, i);
                        break;
                }

        if (qc)
                qc->tag = i;

        return qc;
}

/**
 *      ata_qc_new_init - Request an available ATA command, and initialize it
 *      @ap: Port associated with device @dev
 *      @dev: Device from whom we request an available command structure
 *
 *      LOCKING:
 *      None.
 */

struct ata_queued_cmd *ata_qc_new_init(struct ata_port *ap,
                                      struct ata_device *dev)
{
        struct ata_queued_cmd *qc;

        qc = ata_qc_new(ap);
        if (qc) {
                qc->scsicmd = NULL;
                qc->ap = ap;
                qc->dev = dev;

                ata_qc_reinit(qc);
        }

        return qc;
}

/**
 *      ata_qc_free - free unused ata_queued_cmd
 *      @qc: Command to complete
 *
 *      Designed to free unused ata_queued_cmd object
 *      in case something prevents using it.
 *
 *      LOCKING:
 *      spin_lock_irqsave(host_set lock)
 */
void ata_qc_free(struct ata_queued_cmd *qc)
{
        struct ata_port *ap = qc->ap;
        unsigned int tag;

        WARN_ON(qc == NULL);    /* ata_qc_from_tag _might_ return NULL */

        qc->flags = 0;
        tag = qc->tag;
        if (likely(ata_tag_valid(tag))) {
                if (tag == ap->active_tag)
                        ap->active_tag = ATA_TAG_POISON;
                qc->tag = ATA_TAG_POISON;
                clear_bit(tag, &ap->qactive);
        }
}

void __ata_qc_complete(struct ata_queued_cmd *qc)
{
        WARN_ON(qc == NULL);    /* ata_qc_from_tag _might_ return NULL */
        WARN_ON(!(qc->flags & ATA_QCFLAG_ACTIVE));

        if (likely(qc->flags & ATA_QCFLAG_DMAMAP))
                ata_sg_clean(qc);

        /* atapi: mark qc as inactive to prevent the interrupt handler
         * from completing the command twice later, before the error handler
         * is called. (when rc != 0 and atapi request sense is needed)
         */
        qc->flags &= ~ATA_QCFLAG_ACTIVE;

        /* call completion callback */
        qc->complete_fn(qc);
}

static inline int ata_should_dma_map(struct ata_queued_cmd *qc)
{
        struct ata_port *ap = qc->ap;

        switch (qc->tf.protocol) {
        case ATA_PROT_DMA:
        case ATA_PROT_ATAPI_DMA:
                return 1;

        case ATA_PROT_ATAPI:
        case ATA_PROT_PIO:
        case ATA_PROT_PIO_MULT:
                if (ap->flags & ATA_FLAG_PIO_DMA)
                        return 1;

                /* fall through */

        default:
                return 0;
        }

        /* never reached */
}

/**
 *      ata_qc_issue - issue taskfile to device
 *      @qc: command to issue to device
 *
 *      Prepare an ATA command to submission to device.
 *      This includes mapping the data into a DMA-able
 *      area, filling in the S/G table, and finally
 *      writing the taskfile to hardware, starting the command.
 *
 *      LOCKING:
 *      spin_lock_irqsave(host_set lock)
 *
 *      RETURNS:
 *      Zero on success, AC_ERR_* mask on failure
 */

unsigned int ata_qc_issue(struct ata_queued_cmd *qc)
{
        struct ata_port *ap = qc->ap;

        if (ata_should_dma_map(qc)) {
                if (qc->flags & ATA_QCFLAG_SG) {
                        if (ata_sg_setup(qc))
                                goto sg_err;
                } else if (qc->flags & ATA_QCFLAG_SINGLE) {
                        if (ata_sg_setup_one(qc))
                                goto sg_err;
                }
        } else {
                qc->flags &= ~ATA_QCFLAG_DMAMAP;
        }

        ap->ops->qc_prep(qc);

        qc->ap->active_tag = qc->tag;
        qc->flags |= ATA_QCFLAG_ACTIVE;

        return ap->ops->qc_issue(qc);

sg_err:
        qc->flags &= ~ATA_QCFLAG_DMAMAP;
        return AC_ERR_SYSTEM;
}


/**
 *      ata_qc_issue_prot - issue taskfile to device in proto-dependent manner
 *      @qc: command to issue to device
 *
 *      Using various libata functions and hooks, this function
 *      starts an ATA command.  ATA commands are grouped into
 *      classes called "protocols", and issuing each type of protocol
 *      is slightly different.
 *
 *      May be used as the qc_issue() entry in ata_port_operations.
 *
 *      LOCKING:
 *      spin_lock_irqsave(host_set lock)
 *
 *      RETURNS:
 *      Zero on success, AC_ERR_* mask on failure
 */

unsigned int ata_qc_issue_prot(struct ata_queued_cmd *qc)
{
        struct ata_port *ap = qc->ap;

        ata_dev_select(ap, qc->dev->devno, 1, 0);

        switch (qc->tf.protocol) {
        case ATA_PROT_NODATA:
                ata_tf_to_host(ap, &qc->tf);
                break;

        case ATA_PROT_DMA:
                ap->ops->tf_load(ap, &qc->tf);   /* load tf registers */
                ap->ops->bmdma_setup(qc);           /* set up bmdma */
                ap->ops->bmdma_start(qc);           /* initiate bmdma */
                break;

        case ATA_PROT_PIO: /* load tf registers, initiate polling pio */
                ata_qc_set_polling(qc);
                ata_tf_to_host(ap, &qc->tf);
                ap->hsm_task_state = HSM_ST;
                ata_port_queue_task(ap, ata_pio_task, ap, 0);
                break;

        case ATA_PROT_ATAPI:
                ata_qc_set_polling(qc);
                ata_tf_to_host(ap, &qc->tf);
                ata_port_queue_task(ap, atapi_packet_task, ap, 0);
                break;

        case ATA_PROT_ATAPI_NODATA:
                ap->flags |= ATA_FLAG_NOINTR;
                ata_tf_to_host(ap, &qc->tf);
                ata_port_queue_task(ap, atapi_packet_task, ap, 0);
                break;

        case ATA_PROT_ATAPI_DMA:
                ap->flags |= ATA_FLAG_NOINTR;
                ap->ops->tf_load(ap, &qc->tf);   /* load tf registers */
                ap->ops->bmdma_setup(qc);           /* set up bmdma */
                ata_port_queue_task(ap, atapi_packet_task, ap, 0);
                break;

        default:
                WARN_ON(1);
                return AC_ERR_SYSTEM;
        }

        return 0;
}

/**
 *      ata_bmdma_setup_mmio - Set up PCI IDE BMDMA transaction
 *      @qc: Info associated with this ATA transaction.
 *
 *      LOCKING:
 *      spin_lock_irqsave(host_set lock)
 */

static void ata_bmdma_setup_mmio (struct ata_queued_cmd *qc)
{
        struct ata_port *ap = qc->ap;
        unsigned int rw = (qc->tf.flags & ATA_TFLAG_WRITE);
        u8 dmactl;
        void __iomem *mmio = (void __iomem *) ap->ioaddr.bmdma_addr;

        /* load PRD table addr. */
        mb();   /* make sure PRD table writes are visible to controller */
        writel(ap->prd_dma, mmio + ATA_DMA_TABLE_OFS);

        /* specify data direction, triple-check start bit is clear */
        dmactl = readb(mmio + ATA_DMA_CMD);
        dmactl &= ~(ATA_DMA_WR | ATA_DMA_START);
        if (!rw)
                dmactl |= ATA_DMA_WR;
        writeb(dmactl, mmio + ATA_DMA_CMD);

        /* issue r/w command */
        ap->ops->exec_command(ap, &qc->tf);
}

/**
 *      ata_bmdma_start_mmio - Start a PCI IDE BMDMA transaction
 *      @qc: Info associated with this ATA transaction.
 *
 *      LOCKING:
 *      spin_lock_irqsave(host_set lock)
 */

static void ata_bmdma_start_mmio (struct ata_queued_cmd *qc)
{
        struct ata_port *ap = qc->ap;
        void __iomem *mmio = (void __iomem *) ap->ioaddr.bmdma_addr;
        u8 dmactl;

        /* start host DMA transaction */
        dmactl = readb(mmio + ATA_DMA_CMD);
        writeb(dmactl | ATA_DMA_START, mmio + ATA_DMA_CMD);

        /* Strictly, one may wish to issue a readb() here, to
         * flush the mmio write.  However, control also passes
         * to the hardware at this point, and it will interrupt
         * us when we are to resume control.  So, in effect,
         * we don't care when the mmio write flushes.
         * Further, a read of the DMA status register _immediately_
         * following the write may not be what certain flaky hardware
         * is expected, so I think it is best to not add a readb()
         * without first all the MMIO ATA cards/mobos.
         * Or maybe I'm just being paranoid.
         */
}

/**
 *      ata_bmdma_setup_pio - Set up PCI IDE BMDMA transaction (PIO)
 *      @qc: Info associated with this ATA transaction.
 *
 *      LOCKING:
 *      spin_lock_irqsave(host_set lock)
 */

static void ata_bmdma_setup_pio (struct ata_queued_cmd *qc)
{
        struct ata_port *ap = qc->ap;
        unsigned int rw = (qc->tf.flags & ATA_TFLAG_WRITE);
        u8 dmactl;

        /* load PRD table addr. */
        outl(ap->prd_dma, ap->ioaddr.bmdma_addr + ATA_DMA_TABLE_OFS);

        /* specify data direction, triple-check start bit is clear */
        dmactl = inb(ap->ioaddr.bmdma_addr + ATA_DMA_CMD);
        dmactl &= ~(ATA_DMA_WR | ATA_DMA_START);
        if (!rw)
                dmactl |= ATA_DMA_WR;
        outb(dmactl, ap->ioaddr.bmdma_addr + ATA_DMA_CMD);

        /* issue r/w command */
        ap->ops->exec_command(ap, &qc->tf);
}

/**
 *      ata_bmdma_start_pio - Start a PCI IDE BMDMA transaction (PIO)
 *      @qc: Info associated with this ATA transaction.
 *
 *      LOCKING:
 *      spin_lock_irqsave(host_set lock)
 */

static void ata_bmdma_start_pio (struct ata_queued_cmd *qc)
{
        struct ata_port *ap = qc->ap;
        u8 dmactl;

        /* start host DMA transaction */
        dmactl = inb(ap->ioaddr.bmdma_addr + ATA_DMA_CMD);
        outb(dmactl | ATA_DMA_START,
             ap->ioaddr.bmdma_addr + ATA_DMA_CMD);
}


/**
 *      ata_bmdma_start - Start a PCI IDE BMDMA transaction
 *      @qc: Info associated with this ATA transaction.
 *
 *      Writes the ATA_DMA_START flag to the DMA command register.
 *
 *      May be used as the bmdma_start() entry in ata_port_operations.
 *
 *      LOCKING:
 *      spin_lock_irqsave(host_set lock)
 */
void ata_bmdma_start(struct ata_queued_cmd *qc)
{
        if (qc->ap->flags & ATA_FLAG_MMIO)
                ata_bmdma_start_mmio(qc);
        else
                ata_bmdma_start_pio(qc);
}


/**
 *      ata_bmdma_setup - Set up PCI IDE BMDMA transaction
 *      @qc: Info associated with this ATA transaction.
 *
 *      Writes address of PRD table to device's PRD Table Address
 *      register, sets the DMA control register, and calls
 *      ops->exec_command() to start the transfer.
 *
 *      May be used as the bmdma_setup() entry in ata_port_operations.
 *
 *      LOCKING:
 *      spin_lock_irqsave(host_set lock)
 */
void ata_bmdma_setup(struct ata_queued_cmd *qc)
{
        if (qc->ap->flags & ATA_FLAG_MMIO)
                ata_bmdma_setup_mmio(qc);
        else
                ata_bmdma_setup_pio(qc);
}


/**
 *      ata_bmdma_irq_clear - Clear PCI IDE BMDMA interrupt.
 *      @ap: Port associated with this ATA transaction.
 *
 *      Clear interrupt and error flags in DMA status register.
 *
 *      May be used as the irq_clear() entry in ata_port_operations.
 *
 *      LOCKING:
 *      spin_lock_irqsave(host_set lock)
 */

void ata_bmdma_irq_clear(struct ata_port *ap)
{
    if (ap->flags & ATA_FLAG_MMIO) {
        void __iomem *mmio = ((void __iomem *) ap->ioaddr.bmdma_addr) + ATA_DMA_STATUS;
        writeb(readb(mmio), mmio);
    } else {
        unsigned long addr = ap->ioaddr.bmdma_addr + ATA_DMA_STATUS;
        outb(inb(addr), addr);
    }

}


/**
 *      ata_bmdma_status - Read PCI IDE BMDMA status
 *      @ap: Port associated with this ATA transaction.
 *
 *      Read and return BMDMA status register.
 *
 *      May be used as the bmdma_status() entry in ata_port_operations.
 *
 *      LOCKING:
 *      spin_lock_irqsave(host_set lock)
 */

u8 ata_bmdma_status(struct ata_port *ap)
{
        u8 host_stat;
        if (ap->flags & ATA_FLAG_MMIO) {
                void __iomem *mmio = (void __iomem *) ap->ioaddr.bmdma_addr;
                host_stat = readb(mmio + ATA_DMA_STATUS);
        } else
                host_stat = inb(ap->ioaddr.bmdma_addr + ATA_DMA_STATUS);
        return host_stat;
}


/**
 *      ata_bmdma_stop - Stop PCI IDE BMDMA transfer
 *      @qc: Command we are ending DMA for
 *
 *      Clears the ATA_DMA_START flag in the dma control register
 *
 *      May be used as the bmdma_stop() entry in ata_port_operations.
 *
 *      LOCKING:
 *      spin_lock_irqsave(host_set lock)
 */

void ata_bmdma_stop(struct ata_queued_cmd *qc)
{
        struct ata_port *ap = qc->ap;
        if (ap->flags & ATA_FLAG_MMIO) {
                void __iomem *mmio = (void __iomem *) ap->ioaddr.bmdma_addr;

                /* clear start/stop bit */
                writeb(readb(mmio + ATA_DMA_CMD) & ~ATA_DMA_START,
                        mmio + ATA_DMA_CMD);
        } else {
                /* clear start/stop bit */
                outb(inb(ap->ioaddr.bmdma_addr + ATA_DMA_CMD) & ~ATA_DMA_START,
                        ap->ioaddr.bmdma_addr + ATA_DMA_CMD);
        }

        /* one-PIO-cycle guaranteed wait, per spec, for HDMA1:0 transition */
        ata_altstatus(ap);        /* dummy read */
}

/**
 *      ata_host_intr - Handle host interrupt for given (port, task)
 *      @ap: Port on which interrupt arrived (possibly...)
 *      @qc: Taskfile currently active in engine
 *
 *      Handle host interrupt for given queued command.  Currently,
 *      only DMA interrupts are handled.  All other commands are
 *      handled via polling with interrupts disabled (nIEN bit).
 *
 *      LOCKING:
 *      spin_lock_irqsave(host_set lock)
 *
 *      RETURNS:
 *      One if interrupt was handled, zero if not (shared irq).
 */

inline unsigned int ata_host_intr (struct ata_port *ap,
                                   struct ata_queued_cmd *qc)
{
        u8 status, host_stat;

        switch (qc->tf.protocol) {

        case ATA_PROT_DMA:
        case ATA_PROT_ATAPI_DMA:
        case ATA_PROT_ATAPI:
                /* check status of DMA engine */
                host_stat = ap->ops->bmdma_status(ap);
                VPRINTK("ata%u: host_stat 0x%X\n", ap->id, host_stat);

                /* if it's not our irq... */
                if (!(host_stat & ATA_DMA_INTR))
                        goto idle_irq;

                /* before we do anything else, clear DMA-Start bit */
                ap->ops->bmdma_stop(qc);

                /* fall through */

        case ATA_PROT_ATAPI_NODATA:
        case ATA_PROT_NODATA:
                /* check altstatus */
                status = ata_altstatus(ap);
                if (status & ATA_BUSY)
                        goto idle_irq;

                /* check main status, clearing INTRQ */
                status = ata_chk_status(ap);
                if (unlikely(status & ATA_BUSY))
                        goto idle_irq;
                DPRINTK("ata%u: protocol %d (dev_stat 0x%X)\n",
                        ap->id, qc->tf.protocol, status);

                /* ack bmdma irq events */
                ap->ops->irq_clear(ap);

                /* complete taskfile transaction */
                qc->err_mask |= ac_err_mask(status);
                ata_qc_complete(qc);
                break;

        default:
                goto idle_irq;
        }

        return 1;       /* irq handled */

idle_irq:
        ap->stats.idle_irq++;

#ifdef ATA_IRQ_TRAP
        if ((ap->stats.idle_irq % 1000) == 0) {
                handled = 1;
                ata_irq_ack(ap, 0); /* debug trap */
                printk(KERN_WARNING "ata%d: irq trap\n", ap->id);
        }
#endif
        return 0;       /* irq not handled */
}

/**
 *      ata_interrupt - Default ATA host interrupt handler
 *      @irq: irq line (unused)
 *      @dev_instance: pointer to our ata_host_set information structure
 *      @regs: unused
 *
 *      Default interrupt handler for PCI IDE devices.  Calls
 *      ata_host_intr() for each port that is not disabled.
 *
 *      LOCKING:
 *      Obtains host_set lock during operation.
 *
 *      RETURNS:
 *      IRQ_NONE or IRQ_HANDLED.
 */

irqreturn_t ata_interrupt (int irq, void *dev_instance, struct pt_regs *regs)
{
        struct ata_host_set *host_set = dev_instance;
        unsigned int i;
        unsigned int handled = 0;
        unsigned long flags;

        /* TODO: make _irqsave conditional on x86 PCI IDE legacy mode */
        spin_lock_irqsave(&host_set->lock, flags);

        for (i = 0; i < host_set->n_ports; i++) {
                struct ata_port *ap;

                ap = host_set->ports[i];
                if (ap &&
                    !(ap->flags & (ATA_FLAG_PORT_DISABLED | ATA_FLAG_NOINTR))) {
                        struct ata_queued_cmd *qc;

                        qc = ata_qc_from_tag(ap, ap->active_tag);
                        if (qc && (!(qc->tf.ctl & ATA_NIEN)) &&
                            (qc->flags & ATA_QCFLAG_ACTIVE))
                                handled |= ata_host_intr(ap, qc);
                }
        }

        spin_unlock_irqrestore(&host_set->lock, flags);

        return IRQ_RETVAL(handled);
}


/*
 * Execute a 'simple' command, that only consists of the opcode 'cmd' itself,
 * without filling any other registers
 */
static int ata_do_simple_cmd(struct ata_port *ap, struct ata_device *dev,
                             u8 cmd)
{
        struct ata_taskfile tf;
        int err;

        ata_tf_init(ap, &tf, dev->devno);

        tf.command = cmd;
        tf.flags |= ATA_TFLAG_DEVICE;
        tf.protocol = ATA_PROT_NODATA;

        err = ata_exec_internal(ap, dev, &tf, DMA_NONE, NULL, 0);
        if (err)
                printk(KERN_ERR "%s: ata command failed: %d\n",
                                __FUNCTION__, err);

        return err;
}

static int ata_flush_cache(struct ata_port *ap, struct ata_device *dev)
{
        u8 cmd;

        if (!ata_try_flush_cache(dev))
                return 0;

        if (ata_id_has_flush_ext(dev->id))
                cmd = ATA_CMD_FLUSH_EXT;
        else
                cmd = ATA_CMD_FLUSH;

        return ata_do_simple_cmd(ap, dev, cmd);
}

static int ata_standby_drive(struct ata_port *ap, struct ata_device *dev)
{
        return ata_do_simple_cmd(ap, dev, ATA_CMD_STANDBYNOW1);
}

static int ata_start_drive(struct ata_port *ap, struct ata_device *dev)
{
        return ata_do_simple_cmd(ap, dev, ATA_CMD_IDLEIMMEDIATE);
}

/**
 *      ata_device_resume - wakeup a previously suspended devices
 *      @ap: port the device is connected to
 *      @dev: the device to resume
 *
 *      Kick the drive back into action, by sending it an idle immediate
 *      command and making sure its transfer mode matches between drive
 *      and host.
 *
 */
int ata_device_resume(struct ata_port *ap, struct ata_device *dev)
{
        if (ap->flags & ATA_FLAG_SUSPENDED) {
                ap->flags &= ~ATA_FLAG_SUSPENDED;
                ata_set_mode(ap);
        }
        if (!ata_dev_present(dev))
                return 0;
        if (dev->class == ATA_DEV_ATA)
                ata_start_drive(ap, dev);

        return 0;
}

/**
 *      ata_device_suspend - prepare a device for suspend
 *      @ap: port the device is connected to
 *      @dev: the device to suspend
 *
 *      Flush the cache on the drive, if appropriate, then issue a
 *      standbynow command.
 */
int ata_device_suspend(struct ata_port *ap, struct ata_device *dev)
{
        if (!ata_dev_present(dev))
                return 0;
        if (dev->class == ATA_DEV_ATA)
                ata_flush_cache(ap, dev);

        ata_standby_drive(ap, dev);
        ap->flags |= ATA_FLAG_SUSPENDED;
        return 0;
}

/**
 *      ata_port_start - Set port up for dma.
 *      @ap: Port to initialize
 *
 *      Called just after data structures for each port are
 *      initialized.  Allocates space for PRD table.
 *
 *      May be used as the port_start() entry in ata_port_operations.
 *
 *      LOCKING:
 *      Inherited from caller.
 */

int ata_port_start (struct ata_port *ap)
{
        struct device *dev = ap->host_set->dev;
        int rc;

        ap->prd = dma_alloc_coherent(dev, ATA_PRD_TBL_SZ, &ap->prd_dma, GFP_KERNEL);
        if (!ap->prd)
                return -ENOMEM;

        rc = ata_pad_alloc(ap, dev);
        if (rc) {
                dma_free_coherent(dev, ATA_PRD_TBL_SZ, ap->prd, ap->prd_dma);
                return rc;
        }

        DPRINTK("prd alloc, virt %p, dma %llx\n", ap->prd, (unsigned long long) ap->prd_dma);

        return 0;
}


/**
 *      ata_port_stop - Undo ata_port_start()
 *      @ap: Port to shut down
 *
 *      Frees the PRD table.
 *
 *      May be used as the port_stop() entry in ata_port_operations.
 *
 *      LOCKING:
 *      Inherited from caller.
 */

void ata_port_stop (struct ata_port *ap)
{
        struct device *dev = ap->host_set->dev;

        dma_free_coherent(dev, ATA_PRD_TBL_SZ, ap->prd, ap->prd_dma);
        ata_pad_free(ap, dev);
}

void ata_host_stop (struct ata_host_set *host_set)
{
        if (host_set->mmio_base)
                iounmap(host_set->mmio_base);
}


/**
 *      ata_host_remove - Unregister SCSI host structure with upper layers
 *      @ap: Port to unregister
 *      @do_unregister: 1 if we fully unregister, 0 to just stop the port
 *
 *      LOCKING:
 *      Inherited from caller.
 */

static void ata_host_remove(struct ata_port *ap, unsigned int do_unregister)
{
        struct Scsi_Host *sh = ap->host;

        DPRINTK("ENTER\n");

        if (do_unregister)
                scsi_remove_host(sh);

        ap->ops->port_stop(ap);
}

/**
 *      ata_host_init - Initialize an ata_port structure
 *      @ap: Structure to initialize
 *      @host: associated SCSI mid-layer structure
 *      @host_set: Collection of hosts to which @ap belongs
 *      @ent: Probe information provided by low-level driver
 *      @port_no: Port number associated with this ata_port
 *
 *      Initialize a new ata_port structure, and its associated
 *      scsi_host.
 *
 *      LOCKING:
 *      Inherited from caller.
 */

static void ata_host_init(struct ata_port *ap, struct Scsi_Host *host,
                          struct ata_host_set *host_set,
                          const struct ata_probe_ent *ent, unsigned int port_no)
{
        unsigned int i;

        host->max_id = 16;
        host->max_lun = 1;
        host->max_channel = 1;
        host->unique_id = ata_unique_id++;
        host->max_cmd_len = 12;

        ap->flags = ATA_FLAG_PORT_DISABLED;
        ap->id = host->unique_id;
        ap->host = host;
        ap->ctl = ATA_DEVCTL_OBS;
        ap->host_set = host_set;
        ap->port_no = port_no;
        ap->hard_port_no =
                ent->legacy_mode ? ent->hard_port_no : port_no;
        ap->pio_mask = ent->pio_mask;
        ap->mwdma_mask = ent->mwdma_mask;
        ap->udma_mask = ent->udma_mask;
        ap->flags |= ent->host_flags;
        ap->ops = ent->port_ops;
        ap->cbl = ATA_CBL_NONE;
        ap->active_tag = ATA_TAG_POISON;
        ap->last_ctl = 0xFF;

        INIT_WORK(&ap->port_task, NULL, NULL);
        INIT_LIST_HEAD(&ap->eh_done_q);

        for (i = 0; i < ATA_MAX_DEVICES; i++)
                ap->device[i].devno = i;

#ifdef ATA_IRQ_TRAP
        ap->stats.unhandled_irq = 1;
        ap->stats.idle_irq = 1;
#endif

        memcpy(&ap->ioaddr, &ent->port[port_no], sizeof(struct ata_ioports));
}

/**
 *      ata_host_add - Attach low-level ATA driver to system
 *      @ent: Information provided by low-level driver
 *      @host_set: Collections of ports to which we add
 *      @port_no: Port number associated with this host
 *
 *      Attach low-level ATA driver to system.
 *
 *      LOCKING:
 *      PCI/etc. bus probe sem.
 *
 *      RETURNS:
 *      New ata_port on success, for NULL on error.
 */

static struct ata_port * ata_host_add(const struct ata_probe_ent *ent,
                                      struct ata_host_set *host_set,
                                      unsigned int port_no)
{
        struct Scsi_Host *host;
        struct ata_port *ap;
        int rc;

        DPRINTK("ENTER\n");
        host = scsi_host_alloc(ent->sht, sizeof(struct ata_port));
        if (!host)
                return NULL;

        ap = (struct ata_port *) &host->hostdata[0];

        ata_host_init(ap, host, host_set, ent, port_no);

        rc = ap->ops->port_start(ap);
        if (rc)
                goto err_out;

        return ap;

err_out:
        scsi_host_put(host);
        return NULL;
}

/**
 *      ata_device_add - Register hardware device with ATA and SCSI layers
 *      @ent: Probe information describing hardware device to be registered
 *
 *      This function processes the information provided in the probe
 *      information struct @ent, allocates the necessary ATA and SCSI
 *      host information structures, initializes them, and registers
 *      everything with requisite kernel subsystems.
 *
 *      This function requests irqs, probes the ATA bus, and probes
 *      the SCSI bus.
 *
 *      LOCKING:
 *      PCI/etc. bus probe sem.
 *
 *      RETURNS:
 *      Number of ports registered.  Zero on error (no ports registered).
 */

int ata_device_add(const struct ata_probe_ent *ent)
{
        unsigned int count = 0, i;
        struct device *dev = ent->dev;
        struct ata_host_set *host_set;

        DPRINTK("ENTER\n");
        /* alloc a container for our list of ATA ports (buses) */
        host_set = kzalloc(sizeof(struct ata_host_set) +
                           (ent->n_ports * sizeof(void *)), GFP_KERNEL);
        if (!host_set)
                return 0;
        spin_lock_init(&host_set->lock);

        host_set->dev = dev;
        host_set->n_ports = ent->n_ports;
        host_set->irq = ent->irq;
        host_set->mmio_base = ent->mmio_base;
        host_set->private_data = ent->private_data;
        host_set->ops = ent->port_ops;

        /* register each port bound to this device */
        for (i = 0; i < ent->n_ports; i++) {
                struct ata_port *ap;
                unsigned long xfer_mode_mask;

                ap = ata_host_add(ent, host_set, i);
                if (!ap)
                        goto err_out;

                host_set->ports[i] = ap;
                xfer_mode_mask =(ap->udma_mask << ATA_SHIFT_UDMA) |
                                (ap->mwdma_mask << ATA_SHIFT_MWDMA) |
                                (ap->pio_mask << ATA_SHIFT_PIO);

                /* print per-port info to dmesg */
                printk(KERN_INFO "ata%u: %cATA max %s cmd 0x%lX ctl 0x%lX "
                                 "bmdma 0x%lX irq %lu\n",
                        ap->id,
                        ap->flags & ATA_FLAG_SATA ? 'S' : 'P',
                        ata_mode_string(xfer_mode_mask),
                        ap->ioaddr.cmd_addr,
                        ap->ioaddr.ctl_addr,
                        ap->ioaddr.bmdma_addr,
                        ent->irq);

                ata_chk_status(ap);
                host_set->ops->irq_clear(ap);
                count++;
        }

        if (!count)
                goto err_free_ret;

        /* obtain irq, that is shared between channels */
        if (request_irq(ent->irq, ent->port_ops->irq_handler, ent->irq_flags,
                        DRV_NAME, host_set))
                goto err_out;

        /* perform each probe synchronously */
        DPRINTK("probe begin\n");
        for (i = 0; i < count; i++) {
                struct ata_port *ap;
                int rc;

                ap = host_set->ports[i];

                DPRINTK("ata%u: bus probe begin\n", ap->id);
                rc = ata_bus_probe(ap);
                DPRINTK("ata%u: bus probe end\n", ap->id);

                if (rc) {
                        /* FIXME: do something useful here?
                         * Current libata behavior will
                         * tear down everything when
                         * the module is removed
                         * or the h/w is unplugged.
                         */
                }

                rc = scsi_add_host(ap->host, dev);
                if (rc) {
                        printk(KERN_ERR "ata%u: scsi_add_host failed\n",
                               ap->id);
                        /* FIXME: do something useful here */
                        /* FIXME: handle unconditional calls to
                         * scsi_scan_host and ata_host_remove, below,
                         * at the very least
                         */
                }
        }

        /* probes are done, now scan each port's disk(s) */
        DPRINTK("host probe begin\n");
        for (i = 0; i < count; i++) {
                struct ata_port *ap = host_set->ports[i];

                ata_scsi_scan_host(ap);
        }

        dev_set_drvdata(dev, host_set);

        VPRINTK("EXIT, returning %u\n", ent->n_ports);
        return ent->n_ports; /* success */

err_out:
        for (i = 0; i < count; i++) {
                ata_host_remove(host_set->ports[i], 1);
                scsi_host_put(host_set->ports[i]->host);
        }
err_free_ret:
        kfree(host_set);
        VPRINTK("EXIT, returning 0\n");
        return 0;
}

/**
 *      ata_host_set_remove - PCI layer callback for device removal
 *      @host_set: ATA host set that was removed
 *
 *      Unregister all objects associated with this host set. Free those 
 *      objects.
 *
 *      LOCKING:
 *      Inherited from calling layer (may sleep).
 */

void ata_host_set_remove(struct ata_host_set *host_set)
{
        struct ata_port *ap;
        unsigned int i;

        for (i = 0; i < host_set->n_ports; i++) {
                ap = host_set->ports[i];
                scsi_remove_host(ap->host);
        }

        free_irq(host_set->irq, host_set);

        for (i = 0; i < host_set->n_ports; i++) {
                ap = host_set->ports[i];

                ata_scsi_release(ap->host);

                if ((ap->flags & ATA_FLAG_NO_LEGACY) == 0) {
                        struct ata_ioports *ioaddr = &ap->ioaddr;

                        if (ioaddr->cmd_addr == 0x1f0)
                                release_region(0x1f0, 8);
                        else if (ioaddr->cmd_addr == 0x170)
                                release_region(0x170, 8);
                }

                scsi_host_put(ap->host);
        }

        if (host_set->ops->host_stop)
                host_set->ops->host_stop(host_set);

        kfree(host_set);
}

/**
 *      ata_scsi_release - SCSI layer callback hook for host unload
 *      @host: libata host to be unloaded
 *
 *      Performs all duties necessary to shut down a libata port...
 *      Kill port kthread, disable port, and release resources.
 *
 *      LOCKING:
 *      Inherited from SCSI layer.
 *
 *      RETURNS:
 *      One.
 */

int ata_scsi_release(struct Scsi_Host *host)
{
        struct ata_port *ap = (struct ata_port *) &host->hostdata[0];
        int i;

        DPRINTK("ENTER\n");

        ap->ops->port_disable(ap);
        ata_host_remove(ap, 0);
        for (i = 0; i < ATA_MAX_DEVICES; i++)
                kfree(ap->device[i].id);

        DPRINTK("EXIT\n");
        return 1;
}

/**
 *      ata_std_ports - initialize ioaddr with standard port offsets.
 *      @ioaddr: IO address structure to be initialized
 *
 *      Utility function which initializes data_addr, error_addr,
 *      feature_addr, nsect_addr, lbal_addr, lbam_addr, lbah_addr,
 *      device_addr, status_addr, and command_addr to standard offsets
 *      relative to cmd_addr.
 *
 *      Does not set ctl_addr, altstatus_addr, bmdma_addr, or scr_addr.
 */

void ata_std_ports(struct ata_ioports *ioaddr)
{
        ioaddr->data_addr = ioaddr->cmd_addr + ATA_REG_DATA;
        ioaddr->error_addr = ioaddr->cmd_addr + ATA_REG_ERR;
        ioaddr->feature_addr = ioaddr->cmd_addr + ATA_REG_FEATURE;
        ioaddr->nsect_addr = ioaddr->cmd_addr + ATA_REG_NSECT;
        ioaddr->lbal_addr = ioaddr->cmd_addr + ATA_REG_LBAL;
        ioaddr->lbam_addr = ioaddr->cmd_addr + ATA_REG_LBAM;
        ioaddr->lbah_addr = ioaddr->cmd_addr + ATA_REG_LBAH;
        ioaddr->device_addr = ioaddr->cmd_addr + ATA_REG_DEVICE;
        ioaddr->status_addr = ioaddr->cmd_addr + ATA_REG_STATUS;
        ioaddr->command_addr = ioaddr->cmd_addr + ATA_REG_CMD;
}


#ifdef CONFIG_PCI

void ata_pci_host_stop (struct ata_host_set *host_set)
{
        struct pci_dev *pdev = to_pci_dev(host_set->dev);

        pci_iounmap(pdev, host_set->mmio_base);
}

/**
 *      ata_pci_remove_one - PCI layer callback for device removal
 *      @pdev: PCI device that was removed
 *
 *      PCI layer indicates to libata via this hook that
 *      hot-unplug or module unload event has occurred.
 *      Handle this by unregistering all objects associated
 *      with this PCI device.  Free those objects.  Then finally
 *      release PCI resources and disable device.
 *
 *      LOCKING:
 *      Inherited from PCI layer (may sleep).
 */

void ata_pci_remove_one (struct pci_dev *pdev)
{
        struct device *dev = pci_dev_to_dev(pdev);
        struct ata_host_set *host_set = dev_get_drvdata(dev);

        ata_host_set_remove(host_set);
        pci_release_regions(pdev);
        pci_disable_device(pdev);
        dev_set_drvdata(dev, NULL);
}

/* move to PCI subsystem */
int pci_test_config_bits(struct pci_dev *pdev, const struct pci_bits *bits)
{
        unsigned long tmp = 0;

        switch (bits->width) {
        case 1: {
                u8 tmp8 = 0;
                pci_read_config_byte(pdev, bits->reg, &tmp8);
                tmp = tmp8;
                break;
        }
        case 2: {
                u16 tmp16 = 0;
                pci_read_config_word(pdev, bits->reg, &tmp16);
                tmp = tmp16;
                break;
        }
        case 4: {
                u32 tmp32 = 0;
                pci_read_config_dword(pdev, bits->reg, &tmp32);
                tmp = tmp32;
                break;
        }

        default:
                return -EINVAL;
        }

        tmp &= bits->mask;

        return (tmp == bits->val) ? 1 : 0;
}

int ata_pci_device_suspend(struct pci_dev *pdev, pm_message_t state)
{
        pci_save_state(pdev);
        pci_disable_device(pdev);
        pci_set_power_state(pdev, PCI_D3hot);
        return 0;
}

int ata_pci_device_resume(struct pci_dev *pdev)
{
        pci_set_power_state(pdev, PCI_D0);
        pci_restore_state(pdev);
        pci_enable_device(pdev);
        pci_set_master(pdev);
        return 0;
}
#endif /* CONFIG_PCI */


static int __init ata_init(void)
{
        ata_wq = create_workqueue("ata");
        if (!ata_wq)
                return -ENOMEM;

        printk(KERN_DEBUG "libata version " DRV_VERSION " loaded.\n");
        return 0;
}

static void __exit ata_exit(void)
{
        destroy_workqueue(ata_wq);
}

module_init(ata_init);
module_exit(ata_exit);

static unsigned long ratelimit_time;
static spinlock_t ata_ratelimit_lock = SPIN_LOCK_UNLOCKED;

int ata_ratelimit(void)
{
        int rc;
        unsigned long flags;

        spin_lock_irqsave(&ata_ratelimit_lock, flags);

        if (time_after(jiffies, ratelimit_time)) {
                rc = 1;
                ratelimit_time = jiffies + (HZ/5);
        } else
                rc = 0;

        spin_unlock_irqrestore(&ata_ratelimit_lock, flags);

        return rc;
}

/*
 * libata is essentially a library of internal helper functions for
 * low-level ATA host controller drivers.  As such, the API/ABI is
 * likely to change as new drivers are added and updated.
 * Do not depend on ABI/API stability.
 */

EXPORT_SYMBOL_GPL(ata_std_bios_param);
EXPORT_SYMBOL_GPL(ata_std_ports);
EXPORT_SYMBOL_GPL(ata_device_add);
EXPORT_SYMBOL_GPL(ata_host_set_remove);
EXPORT_SYMBOL_GPL(ata_sg_init);
EXPORT_SYMBOL_GPL(ata_sg_init_one);
EXPORT_SYMBOL_GPL(__ata_qc_complete);
EXPORT_SYMBOL_GPL(ata_qc_issue_prot);
EXPORT_SYMBOL_GPL(ata_eng_timeout);
EXPORT_SYMBOL_GPL(ata_tf_load);
EXPORT_SYMBOL_GPL(ata_tf_read);
EXPORT_SYMBOL_GPL(ata_noop_dev_select);
EXPORT_SYMBOL_GPL(ata_std_dev_select);
EXPORT_SYMBOL_GPL(ata_tf_to_fis);
EXPORT_SYMBOL_GPL(ata_tf_from_fis);
EXPORT_SYMBOL_GPL(ata_check_status);
EXPORT_SYMBOL_GPL(ata_altstatus);
EXPORT_SYMBOL_GPL(ata_exec_command);
EXPORT_SYMBOL_GPL(ata_port_start);
EXPORT_SYMBOL_GPL(ata_port_stop);
EXPORT_SYMBOL_GPL(ata_host_stop);
EXPORT_SYMBOL_GPL(ata_interrupt);
EXPORT_SYMBOL_GPL(ata_qc_prep);
EXPORT_SYMBOL_GPL(ata_bmdma_setup);
EXPORT_SYMBOL_GPL(ata_bmdma_start);
EXPORT_SYMBOL_GPL(ata_bmdma_irq_clear);
EXPORT_SYMBOL_GPL(ata_bmdma_status);
EXPORT_SYMBOL_GPL(ata_bmdma_stop);
EXPORT_SYMBOL_GPL(ata_port_probe);
EXPORT_SYMBOL_GPL(sata_phy_reset);
EXPORT_SYMBOL_GPL(__sata_phy_reset);
EXPORT_SYMBOL_GPL(ata_bus_reset);
EXPORT_SYMBOL_GPL(ata_std_probeinit);
EXPORT_SYMBOL_GPL(ata_std_softreset);
EXPORT_SYMBOL_GPL(sata_std_hardreset);
EXPORT_SYMBOL_GPL(ata_std_postreset);
EXPORT_SYMBOL_GPL(ata_std_probe_reset);
EXPORT_SYMBOL_GPL(ata_drive_probe_reset);
EXPORT_SYMBOL_GPL(ata_dev_revalidate);
EXPORT_SYMBOL_GPL(ata_port_disable);
EXPORT_SYMBOL_GPL(ata_ratelimit);
EXPORT_SYMBOL_GPL(ata_busy_sleep);
EXPORT_SYMBOL_GPL(ata_port_queue_task);
EXPORT_SYMBOL_GPL(ata_scsi_ioctl);
EXPORT_SYMBOL_GPL(ata_scsi_queuecmd);
EXPORT_SYMBOL_GPL(ata_scsi_timed_out);
EXPORT_SYMBOL_GPL(ata_scsi_error);
EXPORT_SYMBOL_GPL(ata_scsi_slave_config);
EXPORT_SYMBOL_GPL(ata_scsi_release);
EXPORT_SYMBOL_GPL(ata_host_intr);
EXPORT_SYMBOL_GPL(ata_dev_classify);
EXPORT_SYMBOL_GPL(ata_id_string);
EXPORT_SYMBOL_GPL(ata_id_c_string);
EXPORT_SYMBOL_GPL(ata_scsi_simulate);
EXPORT_SYMBOL_GPL(ata_eh_qc_complete);
EXPORT_SYMBOL_GPL(ata_eh_qc_retry);

EXPORT_SYMBOL_GPL(ata_pio_need_iordy);
EXPORT_SYMBOL_GPL(ata_timing_compute);
EXPORT_SYMBOL_GPL(ata_timing_merge);

#ifdef CONFIG_PCI
EXPORT_SYMBOL_GPL(pci_test_config_bits);
EXPORT_SYMBOL_GPL(ata_pci_host_stop);
EXPORT_SYMBOL_GPL(ata_pci_init_native_mode);
EXPORT_SYMBOL_GPL(ata_pci_init_one);
EXPORT_SYMBOL_GPL(ata_pci_remove_one);
EXPORT_SYMBOL_GPL(ata_pci_device_suspend);
EXPORT_SYMBOL_GPL(ata_pci_device_resume);
#endif /* CONFIG_PCI */

EXPORT_SYMBOL_GPL(ata_device_suspend);
EXPORT_SYMBOL_GPL(ata_device_resume);
EXPORT_SYMBOL_GPL(ata_scsi_device_suspend);
EXPORT_SYMBOL_GPL(ata_scsi_device_resume);