[deliverable/linux.git] / drivers / usb / host / xhci.c

/*
 * xHCI host controller driver
 *
 * Copyright (C) 2008 Intel Corp.
 *
 * Author: Sarah Sharp
 * Some code borrowed from the Linux EHCI driver.
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License version 2 as
 * published by the Free Software Foundation.
 *
 * 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; if not, write to the Free Software Foundation,
 * Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
 */

#include <linux/pci.h>
#include <linux/irq.h>
#include <linux/log2.h>
#include <linux/module.h>
#include <linux/moduleparam.h>
#include <linux/slab.h>

#include "xhci.h"

#define DRIVER_AUTHOR "Sarah Sharp"
#define DRIVER_DESC "'eXtensible' Host Controller (xHC) Driver"

/* Some 0.95 hardware can't handle the chain bit on a Link TRB being cleared */
static int link_quirk;
module_param(link_quirk, int, S_IRUGO | S_IWUSR);
MODULE_PARM_DESC(link_quirk, "Don't clear the chain bit on a link TRB");

/* TODO: copied from ehci-hcd.c - can this be refactored? */
/*
 * handshake - spin reading hc until handshake completes or fails
 * @ptr: address of hc register to be read
 * @mask: bits to look at in result of read
 * @done: value of those bits when handshake succeeds
 * @usec: timeout in microseconds
 *
 * Returns negative errno, or zero on success
 *
 * Success happens when the "mask" bits have the specified value (hardware
 * handshake done).  There are two failure modes:  "usec" have passed (major
 * hardware flakeout), or the register reads as all-ones (hardware removed).
 */
static int handshake(struct xhci_hcd *xhci, void __iomem *ptr,
                      u32 mask, u32 done, int usec)
{
        u32     result;

        do {
                result = xhci_readl(xhci, ptr);
                if (result == ~(u32)0)          /* card removed */
                        return -ENODEV;
                result &= mask;
                if (result == done)
                        return 0;
                udelay(1);
                usec--;
        } while (usec > 0);
        return -ETIMEDOUT;
}

/*
 * Disable interrupts and begin the xHCI halting process.
 */
void xhci_quiesce(struct xhci_hcd *xhci)
{
        u32 halted;
        u32 cmd;
        u32 mask;

        mask = ~(XHCI_IRQS);
        halted = xhci_readl(xhci, &xhci->op_regs->status) & STS_HALT;
        if (!halted)
                mask &= ~CMD_RUN;

        cmd = xhci_readl(xhci, &xhci->op_regs->command);
        cmd &= mask;
        xhci_writel(xhci, cmd, &xhci->op_regs->command);
}

/*
 * Force HC into halt state.
 *
 * Disable any IRQs and clear the run/stop bit.
 * HC will complete any current and actively pipelined transactions, and
 * should halt within 16 ms of the run/stop bit being cleared.
 * Read HC Halted bit in the status register to see when the HC is finished.
 */
int xhci_halt(struct xhci_hcd *xhci)
{
        int ret;
        xhci_dbg(xhci, "// Halt the HC\n");
        xhci_quiesce(xhci);

        ret = handshake(xhci, &xhci->op_regs->status,
                        STS_HALT, STS_HALT, XHCI_MAX_HALT_USEC);
        if (!ret)
                xhci->xhc_state |= XHCI_STATE_HALTED;
        return ret;
}

/*
 * Set the run bit and wait for the host to be running.
 */
static int xhci_start(struct xhci_hcd *xhci)
{
        u32 temp;
        int ret;

        temp = xhci_readl(xhci, &xhci->op_regs->command);
        temp |= (CMD_RUN);
        xhci_dbg(xhci, "// Turn on HC, cmd = 0x%x.\n",
                        temp);
        xhci_writel(xhci, temp, &xhci->op_regs->command);

        /*
         * Wait for the HCHalted Status bit to be 0 to indicate the host is
         * running.
         */
        ret = handshake(xhci, &xhci->op_regs->status,
                        STS_HALT, 0, XHCI_MAX_HALT_USEC);
        if (ret == -ETIMEDOUT)
                xhci_err(xhci, "Host took too long to start, "
                                "waited %u microseconds.\n",
                                XHCI_MAX_HALT_USEC);
        if (!ret)
                xhci->xhc_state &= ~XHCI_STATE_HALTED;
        return ret;
}

/*
 * Reset a halted HC.
 *
 * This resets pipelines, timers, counters, state machines, etc.
 * Transactions will be terminated immediately, and operational registers
 * will be set to their defaults.
 */
int xhci_reset(struct xhci_hcd *xhci)
{
        u32 command;
        u32 state;
        int ret;

        state = xhci_readl(xhci, &xhci->op_regs->status);
        if ((state & STS_HALT) == 0) {
                xhci_warn(xhci, "Host controller not halted, aborting reset.\n");
                return 0;
        }

        xhci_dbg(xhci, "// Reset the HC\n");
        command = xhci_readl(xhci, &xhci->op_regs->command);
        command |= CMD_RESET;
        xhci_writel(xhci, command, &xhci->op_regs->command);

        ret = handshake(xhci, &xhci->op_regs->command,
                        CMD_RESET, 0, 250 * 1000);
        if (ret)
                return ret;

        xhci_dbg(xhci, "Wait for controller to be ready for doorbell rings\n");
        /*
         * xHCI cannot write to any doorbells or operational registers other
         * than status until the "Controller Not Ready" flag is cleared.
         */
        return handshake(xhci, &xhci->op_regs->status, STS_CNR, 0, 250 * 1000);
}

/*
 * Free IRQs
 * free all IRQs request
 */
static void xhci_free_irq(struct xhci_hcd *xhci)
{
        int i;
        struct pci_dev *pdev = to_pci_dev(xhci_to_hcd(xhci)->self.controller);

        /* return if using legacy interrupt */
        if (xhci_to_hcd(xhci)->irq >= 0)
                return;

        if (xhci->msix_entries) {
                for (i = 0; i < xhci->msix_count; i++)
                        if (xhci->msix_entries[i].vector)
                                free_irq(xhci->msix_entries[i].vector,
                                                xhci_to_hcd(xhci));
        } else if (pdev->irq >= 0)
                free_irq(pdev->irq, xhci_to_hcd(xhci));

        return;
}

/*
 * Set up MSI
 */
static int xhci_setup_msi(struct xhci_hcd *xhci)
{
        int ret;
        struct pci_dev  *pdev = to_pci_dev(xhci_to_hcd(xhci)->self.controller);

        ret = pci_enable_msi(pdev);
        if (ret) {
                xhci_err(xhci, "failed to allocate MSI entry\n");
                return ret;
        }

        ret = request_irq(pdev->irq, (irq_handler_t)xhci_msi_irq,
                                0, "xhci_hcd", xhci_to_hcd(xhci));
        if (ret) {
                xhci_err(xhci, "disable MSI interrupt\n");
                pci_disable_msi(pdev);
        }

        return ret;
}

/*
 * Set up MSI-X
 */
static int xhci_setup_msix(struct xhci_hcd *xhci)
{
        int i, ret = 0;
        struct usb_hcd *hcd = xhci_to_hcd(xhci);
        struct pci_dev *pdev = to_pci_dev(hcd->self.controller);

        /*
         * calculate number of msi-x vectors supported.
         * - HCS_MAX_INTRS: the max number of interrupts the host can handle,
         *   with max number of interrupters based on the xhci HCSPARAMS1.
         * - num_online_cpus: maximum msi-x vectors per CPUs core.
         *   Add additional 1 vector to ensure always available interrupt.
         */
        xhci->msix_count = min(num_online_cpus() + 1,
                                HCS_MAX_INTRS(xhci->hcs_params1));

        xhci->msix_entries =
                kmalloc((sizeof(struct msix_entry))*xhci->msix_count,
                                GFP_KERNEL);
        if (!xhci->msix_entries) {
                xhci_err(xhci, "Failed to allocate MSI-X entries\n");
                return -ENOMEM;
        }

        for (i = 0; i < xhci->msix_count; i++) {
                xhci->msix_entries[i].entry = i;
                xhci->msix_entries[i].vector = 0;
        }

        ret = pci_enable_msix(pdev, xhci->msix_entries, xhci->msix_count);
        if (ret) {
                xhci_err(xhci, "Failed to enable MSI-X\n");
                goto free_entries;
        }

        for (i = 0; i < xhci->msix_count; i++) {
                ret = request_irq(xhci->msix_entries[i].vector,
                                (irq_handler_t)xhci_msi_irq,
                                0, "xhci_hcd", xhci_to_hcd(xhci));
                if (ret)
                        goto disable_msix;
        }

        hcd->msix_enabled = 1;
        return ret;

disable_msix:
        xhci_err(xhci, "disable MSI-X interrupt\n");
        xhci_free_irq(xhci);
        pci_disable_msix(pdev);
free_entries:
        kfree(xhci->msix_entries);
        xhci->msix_entries = NULL;
        return ret;
}

/* Free any IRQs and disable MSI-X */
static void xhci_cleanup_msix(struct xhci_hcd *xhci)
{
        struct usb_hcd *hcd = xhci_to_hcd(xhci);
        struct pci_dev *pdev = to_pci_dev(hcd->self.controller);

        xhci_free_irq(xhci);

        if (xhci->msix_entries) {
                pci_disable_msix(pdev);
                kfree(xhci->msix_entries);
                xhci->msix_entries = NULL;
        } else {
                pci_disable_msi(pdev);
        }

        hcd->msix_enabled = 0;
        return;
}

/*
 * Initialize memory for HCD and xHC (one-time init).
 *
 * Program the PAGESIZE register, initialize the device context array, create
 * device contexts (?), set up a command ring segment (or two?), create event
 * ring (one for now).
 */
int xhci_init(struct usb_hcd *hcd)
{
        struct xhci_hcd *xhci = hcd_to_xhci(hcd);
        int retval = 0;

        xhci_dbg(xhci, "xhci_init\n");
        spin_lock_init(&xhci->lock);
        if (link_quirk) {
                xhci_dbg(xhci, "QUIRK: Not clearing Link TRB chain bits.\n");
                xhci->quirks |= XHCI_LINK_TRB_QUIRK;
        } else {
                xhci_dbg(xhci, "xHCI doesn't need link TRB QUIRK\n");
        }
        retval = xhci_mem_init(xhci, GFP_KERNEL);
        xhci_dbg(xhci, "Finished xhci_init\n");

        return retval;
}

/*-------------------------------------------------------------------------*/


#ifdef CONFIG_USB_XHCI_HCD_DEBUGGING
static void xhci_event_ring_work(unsigned long arg)
{
        unsigned long flags;
        int temp;
        u64 temp_64;
        struct xhci_hcd *xhci = (struct xhci_hcd *) arg;
        int i, j;

        xhci_dbg(xhci, "Poll event ring: %lu\n", jiffies);

        spin_lock_irqsave(&xhci->lock, flags);
        temp = xhci_readl(xhci, &xhci->op_regs->status);
        xhci_dbg(xhci, "op reg status = 0x%x\n", temp);
        if (temp == 0xffffffff || (xhci->xhc_state & XHCI_STATE_DYING)) {
                xhci_dbg(xhci, "HW died, polling stopped.\n");
                spin_unlock_irqrestore(&xhci->lock, flags);
                return;
        }

        temp = xhci_readl(xhci, &xhci->ir_set->irq_pending);
        xhci_dbg(xhci, "ir_set 0 pending = 0x%x\n", temp);
        xhci_dbg(xhci, "HC error bitmask = 0x%x\n", xhci->error_bitmask);
        xhci->error_bitmask = 0;
        xhci_dbg(xhci, "Event ring:\n");
        xhci_debug_segment(xhci, xhci->event_ring->deq_seg);
        xhci_dbg_ring_ptrs(xhci, xhci->event_ring);
        temp_64 = xhci_read_64(xhci, &xhci->ir_set->erst_dequeue);
        temp_64 &= ~ERST_PTR_MASK;
        xhci_dbg(xhci, "ERST deq = 64'h%0lx\n", (long unsigned int) temp_64);
        xhci_dbg(xhci, "Command ring:\n");
        xhci_debug_segment(xhci, xhci->cmd_ring->deq_seg);
        xhci_dbg_ring_ptrs(xhci, xhci->cmd_ring);
        xhci_dbg_cmd_ptrs(xhci);
        for (i = 0; i < MAX_HC_SLOTS; ++i) {
                if (!xhci->devs[i])
                        continue;
                for (j = 0; j < 31; ++j) {
                        xhci_dbg_ep_rings(xhci, i, j, &xhci->devs[i]->eps[j]);
                }
        }
        spin_unlock_irqrestore(&xhci->lock, flags);

        if (!xhci->zombie)
                mod_timer(&xhci->event_ring_timer, jiffies + POLL_TIMEOUT * HZ);
        else
                xhci_dbg(xhci, "Quit polling the event ring.\n");
}
#endif

static int xhci_run_finished(struct xhci_hcd *xhci)
{
        if (xhci_start(xhci)) {
                xhci_halt(xhci);
                return -ENODEV;
        }
        xhci->shared_hcd->state = HC_STATE_RUNNING;

        if (xhci->quirks & XHCI_NEC_HOST)
                xhci_ring_cmd_db(xhci);

        xhci_dbg(xhci, "Finished xhci_run for USB3 roothub\n");
        return 0;
}

/*
 * Start the HC after it was halted.
 *
 * This function is called by the USB core when the HC driver is added.
 * Its opposite is xhci_stop().
 *
 * xhci_init() must be called once before this function can be called.
 * Reset the HC, enable device slot contexts, program DCBAAP, and
 * set command ring pointer and event ring pointer.
 *
 * Setup MSI-X vectors and enable interrupts.
 */
int xhci_run(struct usb_hcd *hcd)
{
        u32 temp;
        u64 temp_64;
        u32 ret;
        struct xhci_hcd *xhci = hcd_to_xhci(hcd);
        struct pci_dev  *pdev = to_pci_dev(xhci_to_hcd(xhci)->self.controller);

        /* Start the xHCI host controller running only after the USB 2.0 roothub
         * is setup.
         */

        hcd->uses_new_polling = 1;
        if (!usb_hcd_is_primary_hcd(hcd))
                return xhci_run_finished(xhci);

        xhci_dbg(xhci, "xhci_run\n");
        /* unregister the legacy interrupt */
        if (hcd->irq)
                free_irq(hcd->irq, hcd);
        hcd->irq = -1;

        /* Some Fresco Logic host controllers advertise MSI, but fail to
         * generate interrupts.  Don't even try to enable MSI.
         */
        if (xhci->quirks & XHCI_BROKEN_MSI)
                goto legacy_irq;

        ret = xhci_setup_msix(xhci);
        if (ret)
                /* fall back to msi*/
                ret = xhci_setup_msi(xhci);

        if (ret) {
legacy_irq:
                /* fall back to legacy interrupt*/
                ret = request_irq(pdev->irq, &usb_hcd_irq, IRQF_SHARED,
                                        hcd->irq_descr, hcd);
                if (ret) {
                        xhci_err(xhci, "request interrupt %d failed\n",
                                        pdev->irq);
                        return ret;
                }
                hcd->irq = pdev->irq;
        }

#ifdef CONFIG_USB_XHCI_HCD_DEBUGGING
        init_timer(&xhci->event_ring_timer);
        xhci->event_ring_timer.data = (unsigned long) xhci;
        xhci->event_ring_timer.function = xhci_event_ring_work;
        /* Poll the event ring */
        xhci->event_ring_timer.expires = jiffies + POLL_TIMEOUT * HZ;
        xhci->zombie = 0;
        xhci_dbg(xhci, "Setting event ring polling timer\n");
        add_timer(&xhci->event_ring_timer);
#endif

        xhci_dbg(xhci, "Command ring memory map follows:\n");
        xhci_debug_ring(xhci, xhci->cmd_ring);
        xhci_dbg_ring_ptrs(xhci, xhci->cmd_ring);
        xhci_dbg_cmd_ptrs(xhci);

        xhci_dbg(xhci, "ERST memory map follows:\n");
        xhci_dbg_erst(xhci, &xhci->erst);
        xhci_dbg(xhci, "Event ring:\n");
        xhci_debug_ring(xhci, xhci->event_ring);
        xhci_dbg_ring_ptrs(xhci, xhci->event_ring);
        temp_64 = xhci_read_64(xhci, &xhci->ir_set->erst_dequeue);
        temp_64 &= ~ERST_PTR_MASK;
        xhci_dbg(xhci, "ERST deq = 64'h%0lx\n", (long unsigned int) temp_64);

        xhci_dbg(xhci, "// Set the interrupt modulation register\n");
        temp = xhci_readl(xhci, &xhci->ir_set->irq_control);
        temp &= ~ER_IRQ_INTERVAL_MASK;
        temp |= (u32) 160;
        xhci_writel(xhci, temp, &xhci->ir_set->irq_control);

        /* Set the HCD state before we enable the irqs */
        temp = xhci_readl(xhci, &xhci->op_regs->command);
        temp |= (CMD_EIE);
        xhci_dbg(xhci, "// Enable interrupts, cmd = 0x%x.\n",
                        temp);
        xhci_writel(xhci, temp, &xhci->op_regs->command);

        temp = xhci_readl(xhci, &xhci->ir_set->irq_pending);
        xhci_dbg(xhci, "// Enabling event ring interrupter %p by writing 0x%x to irq_pending\n",
                        xhci->ir_set, (unsigned int) ER_IRQ_ENABLE(temp));
        xhci_writel(xhci, ER_IRQ_ENABLE(temp),
                        &xhci->ir_set->irq_pending);
        xhci_print_ir_set(xhci, 0);

        if (xhci->quirks & XHCI_NEC_HOST)
                xhci_queue_vendor_command(xhci, 0, 0, 0,
                                TRB_TYPE(TRB_NEC_GET_FW));

        xhci_dbg(xhci, "Finished xhci_run for USB2 roothub\n");
        return 0;
}

static void xhci_only_stop_hcd(struct usb_hcd *hcd)
{
        struct xhci_hcd *xhci = hcd_to_xhci(hcd);

        spin_lock_irq(&xhci->lock);
        xhci_halt(xhci);

        /* The shared_hcd is going to be deallocated shortly (the USB core only
         * calls this function when allocation fails in usb_add_hcd(), or
         * usb_remove_hcd() is called).  So we need to unset xHCI's pointer.
         */
        xhci->shared_hcd = NULL;
        spin_unlock_irq(&xhci->lock);
}

/*
 * Stop xHCI driver.
 *
 * This function is called by the USB core when the HC driver is removed.
 * Its opposite is xhci_run().
 *
 * Disable device contexts, disable IRQs, and quiesce the HC.
 * Reset the HC, finish any completed transactions, and cleanup memory.
 */
void xhci_stop(struct usb_hcd *hcd)
{
        u32 temp;
        struct xhci_hcd *xhci = hcd_to_xhci(hcd);

        if (!usb_hcd_is_primary_hcd(hcd)) {
                xhci_only_stop_hcd(xhci->shared_hcd);
                return;
        }

        spin_lock_irq(&xhci->lock);
        /* Make sure the xHC is halted for a USB3 roothub
         * (xhci_stop() could be called as part of failed init).
         */
        xhci_halt(xhci);
        xhci_reset(xhci);
        spin_unlock_irq(&xhci->lock);

        xhci_cleanup_msix(xhci);

#ifdef CONFIG_USB_XHCI_HCD_DEBUGGING
        /* Tell the event ring poll function not to reschedule */
        xhci->zombie = 1;
        del_timer_sync(&xhci->event_ring_timer);
#endif

        if (xhci->quirks & XHCI_AMD_PLL_FIX)
                usb_amd_dev_put();

        xhci_dbg(xhci, "// Disabling event ring interrupts\n");
        temp = xhci_readl(xhci, &xhci->op_regs->status);
        xhci_writel(xhci, temp & ~STS_EINT, &xhci->op_regs->status);
        temp = xhci_readl(xhci, &xhci->ir_set->irq_pending);
        xhci_writel(xhci, ER_IRQ_DISABLE(temp),
                        &xhci->ir_set->irq_pending);
        xhci_print_ir_set(xhci, 0);

        xhci_dbg(xhci, "cleaning up memory\n");
        xhci_mem_cleanup(xhci);
        xhci_dbg(xhci, "xhci_stop completed - status = %x\n",
                    xhci_readl(xhci, &xhci->op_regs->status));
}

/*
 * Shutdown HC (not bus-specific)
 *
 * This is called when the machine is rebooting or halting.  We assume that the
 * machine will be powered off, and the HC's internal state will be reset.
 * Don't bother to free memory.
 *
 * This will only ever be called with the main usb_hcd (the USB3 roothub).
 */
void xhci_shutdown(struct usb_hcd *hcd)
{
        struct xhci_hcd *xhci = hcd_to_xhci(hcd);

        spin_lock_irq(&xhci->lock);
        xhci_halt(xhci);
        spin_unlock_irq(&xhci->lock);

        xhci_cleanup_msix(xhci);

        xhci_dbg(xhci, "xhci_shutdown completed - status = %x\n",
                    xhci_readl(xhci, &xhci->op_regs->status));
}

#ifdef CONFIG_PM
static void xhci_save_registers(struct xhci_hcd *xhci)
{
        xhci->s3.command = xhci_readl(xhci, &xhci->op_regs->command);
        xhci->s3.dev_nt = xhci_readl(xhci, &xhci->op_regs->dev_notification);
        xhci->s3.dcbaa_ptr = xhci_read_64(xhci, &xhci->op_regs->dcbaa_ptr);
        xhci->s3.config_reg = xhci_readl(xhci, &xhci->op_regs->config_reg);
        xhci->s3.irq_pending = xhci_readl(xhci, &xhci->ir_set->irq_pending);
        xhci->s3.irq_control = xhci_readl(xhci, &xhci->ir_set->irq_control);
        xhci->s3.erst_size = xhci_readl(xhci, &xhci->ir_set->erst_size);
        xhci->s3.erst_base = xhci_read_64(xhci, &xhci->ir_set->erst_base);
        xhci->s3.erst_dequeue = xhci_read_64(xhci, &xhci->ir_set->erst_dequeue);
}

static void xhci_restore_registers(struct xhci_hcd *xhci)
{
        xhci_writel(xhci, xhci->s3.command, &xhci->op_regs->command);
        xhci_writel(xhci, xhci->s3.dev_nt, &xhci->op_regs->dev_notification);
        xhci_write_64(xhci, xhci->s3.dcbaa_ptr, &xhci->op_regs->dcbaa_ptr);
        xhci_writel(xhci, xhci->s3.config_reg, &xhci->op_regs->config_reg);
        xhci_writel(xhci, xhci->s3.irq_pending, &xhci->ir_set->irq_pending);
        xhci_writel(xhci, xhci->s3.irq_control, &xhci->ir_set->irq_control);
        xhci_writel(xhci, xhci->s3.erst_size, &xhci->ir_set->erst_size);
        xhci_write_64(xhci, xhci->s3.erst_base, &xhci->ir_set->erst_base);
}

static void xhci_set_cmd_ring_deq(struct xhci_hcd *xhci)
{
        u64     val_64;

        /* step 2: initialize command ring buffer */
        val_64 = xhci_read_64(xhci, &xhci->op_regs->cmd_ring);
        val_64 = (val_64 & (u64) CMD_RING_RSVD_BITS) |
                (xhci_trb_virt_to_dma(xhci->cmd_ring->deq_seg,
                                      xhci->cmd_ring->dequeue) &
                 (u64) ~CMD_RING_RSVD_BITS) |
                xhci->cmd_ring->cycle_state;
        xhci_dbg(xhci, "// Setting command ring address to 0x%llx\n",
                        (long unsigned long) val_64);
        xhci_write_64(xhci, val_64, &xhci->op_regs->cmd_ring);
}

/*
 * The whole command ring must be cleared to zero when we suspend the host.
 *
 * The host doesn't save the command ring pointer in the suspend well, so we
 * need to re-program it on resume.  Unfortunately, the pointer must be 64-byte
 * aligned, because of the reserved bits in the command ring dequeue pointer
 * register.  Therefore, we can't just set the dequeue pointer back in the
 * middle of the ring (TRBs are 16-byte aligned).
 */
static void xhci_clear_command_ring(struct xhci_hcd *xhci)
{
        struct xhci_ring *ring;
        struct xhci_segment *seg;

        ring = xhci->cmd_ring;
        seg = ring->deq_seg;
        do {
                memset(seg->trbs, 0, SEGMENT_SIZE);
                seg = seg->next;
        } while (seg != ring->deq_seg);

        /* Reset the software enqueue and dequeue pointers */
        ring->deq_seg = ring->first_seg;
        ring->dequeue = ring->first_seg->trbs;
        ring->enq_seg = ring->deq_seg;
        ring->enqueue = ring->dequeue;

        /*
         * Ring is now zeroed, so the HW should look for change of ownership
         * when the cycle bit is set to 1.
         */
        ring->cycle_state = 1;

        /*
         * Reset the hardware dequeue pointer.
         * Yes, this will need to be re-written after resume, but we're paranoid
         * and want to make sure the hardware doesn't access bogus memory
         * because, say, the BIOS or an SMI started the host without changing
         * the command ring pointers.
         */
        xhci_set_cmd_ring_deq(xhci);
}

/*
 * Stop HC (not bus-specific)
 *
 * This is called when the machine transition into S3/S4 mode.
 *
 */
int xhci_suspend(struct xhci_hcd *xhci)
{
        int                     rc = 0;
        struct usb_hcd          *hcd = xhci_to_hcd(xhci);
        u32                     command;
        int                     i;

        spin_lock_irq(&xhci->lock);
        clear_bit(HCD_FLAG_HW_ACCESSIBLE, &hcd->flags);
        clear_bit(HCD_FLAG_HW_ACCESSIBLE, &xhci->shared_hcd->flags);
        /* step 1: stop endpoint */
        /* skipped assuming that port suspend has done */

        /* step 2: clear Run/Stop bit */
        command = xhci_readl(xhci, &xhci->op_regs->command);
        command &= ~CMD_RUN;
        xhci_writel(xhci, command, &xhci->op_regs->command);
        if (handshake(xhci, &xhci->op_regs->status,
                      STS_HALT, STS_HALT, 100*100)) {
                xhci_warn(xhci, "WARN: xHC CMD_RUN timeout\n");
                spin_unlock_irq(&xhci->lock);
                return -ETIMEDOUT;
        }
        xhci_clear_command_ring(xhci);

        /* step 3: save registers */
        xhci_save_registers(xhci);

        /* step 4: set CSS flag */
        command = xhci_readl(xhci, &xhci->op_regs->command);
        command |= CMD_CSS;
        xhci_writel(xhci, command, &xhci->op_regs->command);
        if (handshake(xhci, &xhci->op_regs->status, STS_SAVE, 0, 10*100)) {
                xhci_warn(xhci, "WARN: xHC CMD_CSS timeout\n");
                spin_unlock_irq(&xhci->lock);
                return -ETIMEDOUT;
        }
        spin_unlock_irq(&xhci->lock);

        /* step 5: remove core well power */
        /* synchronize irq when using MSI-X */
        if (xhci->msix_entries) {
                for (i = 0; i < xhci->msix_count; i++)
                        synchronize_irq(xhci->msix_entries[i].vector);
        }

        return rc;
}

/*
 * start xHC (not bus-specific)
 *
 * This is called when the machine transition from S3/S4 mode.
 *
 */
int xhci_resume(struct xhci_hcd *xhci, bool hibernated)
{
        u32                     command, temp = 0;
        struct usb_hcd          *hcd = xhci_to_hcd(xhci);
        struct usb_hcd          *secondary_hcd;
        int                     retval;

        /* Wait a bit if either of the roothubs need to settle from the
         * transition into bus suspend.
         */
        if (time_before(jiffies, xhci->bus_state[0].next_statechange) ||
                        time_before(jiffies,
                                xhci->bus_state[1].next_statechange))
                msleep(100);

        spin_lock_irq(&xhci->lock);

        if (!hibernated) {
                /* step 1: restore register */
                xhci_restore_registers(xhci);
                /* step 2: initialize command ring buffer */
                xhci_set_cmd_ring_deq(xhci);
                /* step 3: restore state and start state*/
                /* step 3: set CRS flag */
                command = xhci_readl(xhci, &xhci->op_regs->command);
                command |= CMD_CRS;
                xhci_writel(xhci, command, &xhci->op_regs->command);
                if (handshake(xhci, &xhci->op_regs->status,
                              STS_RESTORE, 0, 10*100)) {
                        xhci_dbg(xhci, "WARN: xHC CMD_CSS timeout\n");
                        spin_unlock_irq(&xhci->lock);
                        return -ETIMEDOUT;
                }
                temp = xhci_readl(xhci, &xhci->op_regs->status);
        }

        /* If restore operation fails, re-initialize the HC during resume */
        if ((temp & STS_SRE) || hibernated) {
                /* Let the USB core know _both_ roothubs lost power. */
                usb_root_hub_lost_power(xhci->main_hcd->self.root_hub);
                usb_root_hub_lost_power(xhci->shared_hcd->self.root_hub);

                xhci_dbg(xhci, "Stop HCD\n");
                xhci_halt(xhci);
                xhci_reset(xhci);
                spin_unlock_irq(&xhci->lock);
                xhci_cleanup_msix(xhci);

#ifdef CONFIG_USB_XHCI_HCD_DEBUGGING
                /* Tell the event ring poll function not to reschedule */
                xhci->zombie = 1;
                del_timer_sync(&xhci->event_ring_timer);
#endif

                xhci_dbg(xhci, "// Disabling event ring interrupts\n");
                temp = xhci_readl(xhci, &xhci->op_regs->status);
                xhci_writel(xhci, temp & ~STS_EINT, &xhci->op_regs->status);
                temp = xhci_readl(xhci, &xhci->ir_set->irq_pending);
                xhci_writel(xhci, ER_IRQ_DISABLE(temp),
                                &xhci->ir_set->irq_pending);
                xhci_print_ir_set(xhci, 0);

                xhci_dbg(xhci, "cleaning up memory\n");
                xhci_mem_cleanup(xhci);
                xhci_dbg(xhci, "xhci_stop completed - status = %x\n",
                            xhci_readl(xhci, &xhci->op_regs->status));

                /* USB core calls the PCI reinit and start functions twice:
                 * first with the primary HCD, and then with the secondary HCD.
                 * If we don't do the same, the host will never be started.
                 */
                if (!usb_hcd_is_primary_hcd(hcd))
                        secondary_hcd = hcd;
                else
                        secondary_hcd = xhci->shared_hcd;

                xhci_dbg(xhci, "Initialize the xhci_hcd\n");
                retval = xhci_init(hcd->primary_hcd);
                if (retval)
                        return retval;
                xhci_dbg(xhci, "Start the primary HCD\n");
                retval = xhci_run(hcd->primary_hcd);
                if (retval)
                        goto failed_restart;

                xhci_dbg(xhci, "Start the secondary HCD\n");
                retval = xhci_run(secondary_hcd);
                if (!retval) {
                        set_bit(HCD_FLAG_HW_ACCESSIBLE, &hcd->flags);
                        set_bit(HCD_FLAG_HW_ACCESSIBLE,
                                        &xhci->shared_hcd->flags);
                }
failed_restart:
                hcd->state = HC_STATE_SUSPENDED;
                xhci->shared_hcd->state = HC_STATE_SUSPENDED;
                return retval;
        }

        /* step 4: set Run/Stop bit */
        command = xhci_readl(xhci, &xhci->op_regs->command);
        command |= CMD_RUN;
        xhci_writel(xhci, command, &xhci->op_regs->command);
        handshake(xhci, &xhci->op_regs->status, STS_HALT,
                  0, 250 * 1000);

        /* step 5: walk topology and initialize portsc,
         * portpmsc and portli
         */
        /* this is done in bus_resume */

        /* step 6: restart each of the previously
         * Running endpoints by ringing their doorbells
         */

        set_bit(HCD_FLAG_HW_ACCESSIBLE, &hcd->flags);
        set_bit(HCD_FLAG_HW_ACCESSIBLE, &xhci->shared_hcd->flags);

        spin_unlock_irq(&xhci->lock);
        return 0;
}
#endif  /* CONFIG_PM */

/*-------------------------------------------------------------------------*/

/**
 * xhci_get_endpoint_index - Used for passing endpoint bitmasks between the core and
 * HCDs.  Find the index for an endpoint given its descriptor.  Use the return
 * value to right shift 1 for the bitmask.
 *
 * Index  = (epnum * 2) + direction - 1,
 * where direction = 0 for OUT, 1 for IN.
 * For control endpoints, the IN index is used (OUT index is unused), so
 * index = (epnum * 2) + direction - 1 = (epnum * 2) + 1 - 1 = (epnum * 2)
 */
unsigned int xhci_get_endpoint_index(struct usb_endpoint_descriptor *desc)
{
        unsigned int index;
        if (usb_endpoint_xfer_control(desc))
                index = (unsigned int) (usb_endpoint_num(desc)*2);
        else
                index = (unsigned int) (usb_endpoint_num(desc)*2) +
                        (usb_endpoint_dir_in(desc) ? 1 : 0) - 1;
        return index;
}

/* Find the flag for this endpoint (for use in the control context).  Use the
 * endpoint index to create a bitmask.  The slot context is bit 0, endpoint 0 is
 * bit 1, etc.
 */
unsigned int xhci_get_endpoint_flag(struct usb_endpoint_descriptor *desc)
{
        return 1 << (xhci_get_endpoint_index(desc) + 1);
}

/* Find the flag for this endpoint (for use in the control context).  Use the
 * endpoint index to create a bitmask.  The slot context is bit 0, endpoint 0 is
 * bit 1, etc.
 */
unsigned int xhci_get_endpoint_flag_from_index(unsigned int ep_index)
{
        return 1 << (ep_index + 1);
}

/* Compute the last valid endpoint context index.  Basically, this is the
 * endpoint index plus one.  For slot contexts with more than valid endpoint,
 * we find the most significant bit set in the added contexts flags.
 * e.g. ep 1 IN (with epnum 0x81) => added_ctxs = 0b1000
 * fls(0b1000) = 4, but the endpoint context index is 3, so subtract one.
 */
unsigned int xhci_last_valid_endpoint(u32 added_ctxs)
{
        return fls(added_ctxs) - 1;
}

/* Returns 1 if the arguments are OK;
 * returns 0 this is a root hub; returns -EINVAL for NULL pointers.
 */
static int xhci_check_args(struct usb_hcd *hcd, struct usb_device *udev,
                struct usb_host_endpoint *ep, int check_ep, bool check_virt_dev,
                const char *func) {
        struct xhci_hcd *xhci;
        struct xhci_virt_device *virt_dev;

        if (!hcd || (check_ep && !ep) || !udev) {
                printk(KERN_DEBUG "xHCI %s called with invalid args\n",
                                func);
                return -EINVAL;
        }
        if (!udev->parent) {
                printk(KERN_DEBUG "xHCI %s called for root hub\n",
                                func);
                return 0;
        }

        if (check_virt_dev) {
                xhci = hcd_to_xhci(hcd);
                if (!udev->slot_id || !xhci->devs
                        || !xhci->devs[udev->slot_id]) {
                        printk(KERN_DEBUG "xHCI %s called with unaddressed "
                                                "device\n", func);
                        return -EINVAL;
                }

                virt_dev = xhci->devs[udev->slot_id];
                if (virt_dev->udev != udev) {
                        printk(KERN_DEBUG "xHCI %s called with udev and "
                                          "virt_dev does not match\n", func);
                        return -EINVAL;
                }
        }

        return 1;
}

static int xhci_configure_endpoint(struct xhci_hcd *xhci,
                struct usb_device *udev, struct xhci_command *command,
                bool ctx_change, bool must_succeed);

/*
 * Full speed devices may have a max packet size greater than 8 bytes, but the
 * USB core doesn't know that until it reads the first 8 bytes of the
 * descriptor.  If the usb_device's max packet size changes after that point,
 * we need to issue an evaluate context command and wait on it.
 */
static int xhci_check_maxpacket(struct xhci_hcd *xhci, unsigned int slot_id,
                unsigned int ep_index, struct urb *urb)
{
        struct xhci_container_ctx *in_ctx;
        struct xhci_container_ctx *out_ctx;
        struct xhci_input_control_ctx *ctrl_ctx;
        struct xhci_ep_ctx *ep_ctx;
        int max_packet_size;
        int hw_max_packet_size;
        int ret = 0;

        out_ctx = xhci->devs[slot_id]->out_ctx;
        ep_ctx = xhci_get_ep_ctx(xhci, out_ctx, ep_index);
        hw_max_packet_size = MAX_PACKET_DECODED(le32_to_cpu(ep_ctx->ep_info2));
        max_packet_size = le16_to_cpu(urb->dev->ep0.desc.wMaxPacketSize);
        if (hw_max_packet_size != max_packet_size) {
                xhci_dbg(xhci, "Max Packet Size for ep 0 changed.\n");
                xhci_dbg(xhci, "Max packet size in usb_device = %d\n",
                                max_packet_size);
                xhci_dbg(xhci, "Max packet size in xHCI HW = %d\n",
                                hw_max_packet_size);
                xhci_dbg(xhci, "Issuing evaluate context command.\n");

                /* Set up the modified control endpoint 0 */
                xhci_endpoint_copy(xhci, xhci->devs[slot_id]->in_ctx,
                                xhci->devs[slot_id]->out_ctx, ep_index);
                in_ctx = xhci->devs[slot_id]->in_ctx;
                ep_ctx = xhci_get_ep_ctx(xhci, in_ctx, ep_index);
                ep_ctx->ep_info2 &= cpu_to_le32(~MAX_PACKET_MASK);
                ep_ctx->ep_info2 |= cpu_to_le32(MAX_PACKET(max_packet_size));

                /* Set up the input context flags for the command */
                /* FIXME: This won't work if a non-default control endpoint
                 * changes max packet sizes.
                 */
                ctrl_ctx = xhci_get_input_control_ctx(xhci, in_ctx);
                ctrl_ctx->add_flags = cpu_to_le32(EP0_FLAG);
                ctrl_ctx->drop_flags = 0;

                xhci_dbg(xhci, "Slot %d input context\n", slot_id);
                xhci_dbg_ctx(xhci, in_ctx, ep_index);
                xhci_dbg(xhci, "Slot %d output context\n", slot_id);
                xhci_dbg_ctx(xhci, out_ctx, ep_index);

                ret = xhci_configure_endpoint(xhci, urb->dev, NULL,
                                true, false);

                /* Clean up the input context for later use by bandwidth
                 * functions.
                 */
                ctrl_ctx->add_flags = cpu_to_le32(SLOT_FLAG);
        }
        return ret;
}

/*
 * non-error returns are a promise to giveback() the urb later
 * we drop ownership so next owner (or urb unlink) can get it
 */
int xhci_urb_enqueue(struct usb_hcd *hcd, struct urb *urb, gfp_t mem_flags)
{
        struct xhci_hcd *xhci = hcd_to_xhci(hcd);
        unsigned long flags;
        int ret = 0;
        unsigned int slot_id, ep_index;
        struct urb_priv *urb_priv;
        int size, i;

        if (!urb || xhci_check_args(hcd, urb->dev, urb->ep,
                                        true, true, __func__) <= 0)
                return -EINVAL;

        slot_id = urb->dev->slot_id;
        ep_index = xhci_get_endpoint_index(&urb->ep->desc);

        if (!HCD_HW_ACCESSIBLE(hcd)) {
                if (!in_interrupt())
                        xhci_dbg(xhci, "urb submitted during PCI suspend\n");
                ret = -ESHUTDOWN;
                goto exit;
        }

        if (usb_endpoint_xfer_isoc(&urb->ep->desc))
                size = urb->number_of_packets;
        else
                size = 1;

        urb_priv = kzalloc(sizeof(struct urb_priv) +
                                  size * sizeof(struct xhci_td *), mem_flags);
        if (!urb_priv)
                return -ENOMEM;

        for (i = 0; i < size; i++) {
                urb_priv->td[i] = kzalloc(sizeof(struct xhci_td), mem_flags);
                if (!urb_priv->td[i]) {
                        urb_priv->length = i;
                        xhci_urb_free_priv(xhci, urb_priv);
                        return -ENOMEM;
                }
        }

        urb_priv->length = size;
        urb_priv->td_cnt = 0;
        urb->hcpriv = urb_priv;

        if (usb_endpoint_xfer_control(&urb->ep->desc)) {
                /* Check to see if the max packet size for the default control
                 * endpoint changed during FS device enumeration
                 */
                if (urb->dev->speed == USB_SPEED_FULL) {
                        ret = xhci_check_maxpacket(xhci, slot_id,
                                        ep_index, urb);
                        if (ret < 0)
                                return ret;
                }

                /* We have a spinlock and interrupts disabled, so we must pass
                 * atomic context to this function, which may allocate memory.
                 */
                spin_lock_irqsave(&xhci->lock, flags);
                if (xhci->xhc_state & XHCI_STATE_DYING)
                        goto dying;
                ret = xhci_queue_ctrl_tx(xhci, GFP_ATOMIC, urb,
                                slot_id, ep_index);
                spin_unlock_irqrestore(&xhci->lock, flags);
        } else if (usb_endpoint_xfer_bulk(&urb->ep->desc)) {
                spin_lock_irqsave(&xhci->lock, flags);
                if (xhci->xhc_state & XHCI_STATE_DYING)
                        goto dying;
                if (xhci->devs[slot_id]->eps[ep_index].ep_state &
                                EP_GETTING_STREAMS) {
                        xhci_warn(xhci, "WARN: Can't enqueue URB while bulk ep "
                                        "is transitioning to using streams.\n");
                        ret = -EINVAL;
                } else if (xhci->devs[slot_id]->eps[ep_index].ep_state &
                                EP_GETTING_NO_STREAMS) {
                        xhci_warn(xhci, "WARN: Can't enqueue URB while bulk ep "
                                        "is transitioning to "
                                        "not having streams.\n");
                        ret = -EINVAL;
                } else {
                        ret = xhci_queue_bulk_tx(xhci, GFP_ATOMIC, urb,
                                        slot_id, ep_index);
                }
                spin_unlock_irqrestore(&xhci->lock, flags);
        } else if (usb_endpoint_xfer_int(&urb->ep->desc)) {
                spin_lock_irqsave(&xhci->lock, flags);
                if (xhci->xhc_state & XHCI_STATE_DYING)
                        goto dying;
                ret = xhci_queue_intr_tx(xhci, GFP_ATOMIC, urb,
                                slot_id, ep_index);
                spin_unlock_irqrestore(&xhci->lock, flags);
        } else {
                spin_lock_irqsave(&xhci->lock, flags);
                if (xhci->xhc_state & XHCI_STATE_DYING)
                        goto dying;
                ret = xhci_queue_isoc_tx_prepare(xhci, GFP_ATOMIC, urb,
                                slot_id, ep_index);
                spin_unlock_irqrestore(&xhci->lock, flags);
        }
exit:
        return ret;
dying:
        xhci_urb_free_priv(xhci, urb_priv);
        urb->hcpriv = NULL;
        xhci_dbg(xhci, "Ep 0x%x: URB %p submitted for "
                        "non-responsive xHCI host.\n",
                        urb->ep->desc.bEndpointAddress, urb);
        spin_unlock_irqrestore(&xhci->lock, flags);
        return -ESHUTDOWN;
}

/* Get the right ring for the given URB.
 * If the endpoint supports streams, boundary check the URB's stream ID.
 * If the endpoint doesn't support streams, return the singular endpoint ring.
 */
static struct xhci_ring *xhci_urb_to_transfer_ring(struct xhci_hcd *xhci,
                struct urb *urb)
{
        unsigned int slot_id;
        unsigned int ep_index;
        unsigned int stream_id;
        struct xhci_virt_ep *ep;

        slot_id = urb->dev->slot_id;
        ep_index = xhci_get_endpoint_index(&urb->ep->desc);
        stream_id = urb->stream_id;
        ep = &xhci->devs[slot_id]->eps[ep_index];
        /* Common case: no streams */
        if (!(ep->ep_state & EP_HAS_STREAMS))
                return ep->ring;

        if (stream_id == 0) {
                xhci_warn(xhci,
                                "WARN: Slot ID %u, ep index %u has streams, "
                                "but URB has no stream ID.\n",
                                slot_id, ep_index);
                return NULL;
        }

        if (stream_id < ep->stream_info->num_streams)
                return ep->stream_info->stream_rings[stream_id];

        xhci_warn(xhci,
                        "WARN: Slot ID %u, ep index %u has "
                        "stream IDs 1 to %u allocated, "
                        "but stream ID %u is requested.\n",
                        slot_id, ep_index,
                        ep->stream_info->num_streams - 1,
                        stream_id);
        return NULL;
}

/*
 * Remove the URB's TD from the endpoint ring.  This may cause the HC to stop
 * USB transfers, potentially stopping in the middle of a TRB buffer.  The HC
 * should pick up where it left off in the TD, unless a Set Transfer Ring
 * Dequeue Pointer is issued.
 *
 * The TRBs that make up the buffers for the canceled URB will be "removed" from
 * the ring.  Since the ring is a contiguous structure, they can't be physically
 * removed.  Instead, there are two options:
 *
 *  1) If the HC is in the middle of processing the URB to be canceled, we
 *     simply move the ring's dequeue pointer past those TRBs using the Set
 *     Transfer Ring Dequeue Pointer command.  This will be the common case,
 *     when drivers timeout on the last submitted URB and attempt to cancel.
 *
 *  2) If the HC is in the middle of a different TD, we turn the TRBs into a
 *     series of 1-TRB transfer no-op TDs.  (No-ops shouldn't be chained.)  The
 *     HC will need to invalidate the any TRBs it has cached after the stop
 *     endpoint command, as noted in the xHCI 0.95 errata.
 *
 *  3) The TD may have completed by the time the Stop Endpoint Command
 *     completes, so software needs to handle that case too.
 *
 * This function should protect against the TD enqueueing code ringing the
 * doorbell while this code is waiting for a Stop Endpoint command to complete.
 * It also needs to account for multiple cancellations on happening at the same
 * time for the same endpoint.
 *
 * Note that this function can be called in any context, or so says
 * usb_hcd_unlink_urb()
 */
int xhci_urb_dequeue(struct usb_hcd *hcd, struct urb *urb, int status)
{
        unsigned long flags;
        int ret, i;
        u32 temp;
        struct xhci_hcd *xhci;
        struct urb_priv *urb_priv;
        struct xhci_td *td;
        unsigned int ep_index;
        struct xhci_ring *ep_ring;
        struct xhci_virt_ep *ep;

        xhci = hcd_to_xhci(hcd);
        spin_lock_irqsave(&xhci->lock, flags);
        /* Make sure the URB hasn't completed or been unlinked already */
        ret = usb_hcd_check_unlink_urb(hcd, urb, status);
        if (ret || !urb->hcpriv)
                goto done;
        temp = xhci_readl(xhci, &xhci->op_regs->status);
        if (temp == 0xffffffff || (xhci->xhc_state & XHCI_STATE_HALTED)) {
                xhci_dbg(xhci, "HW died, freeing TD.\n");
                urb_priv = urb->hcpriv;

                usb_hcd_unlink_urb_from_ep(hcd, urb);
                spin_unlock_irqrestore(&xhci->lock, flags);
                usb_hcd_giveback_urb(hcd, urb, -ESHUTDOWN);
                xhci_urb_free_priv(xhci, urb_priv);
                return ret;
        }
        if (xhci->xhc_state & XHCI_STATE_DYING) {
                xhci_dbg(xhci, "Ep 0x%x: URB %p to be canceled on "
                                "non-responsive xHCI host.\n",
                                urb->ep->desc.bEndpointAddress, urb);
                /* Let the stop endpoint command watchdog timer (which set this
                 * state) finish cleaning up the endpoint TD lists.  We must
                 * have caught it in the middle of dropping a lock and giving
                 * back an URB.
                 */
                goto done;
        }

        xhci_dbg(xhci, "Cancel URB %p\n", urb);
        xhci_dbg(xhci, "Event ring:\n");
        xhci_debug_ring(xhci, xhci->event_ring);
        ep_index = xhci_get_endpoint_index(&urb->ep->desc);
        ep = &xhci->devs[urb->dev->slot_id]->eps[ep_index];
        ep_ring = xhci_urb_to_transfer_ring(xhci, urb);
        if (!ep_ring) {
                ret = -EINVAL;
                goto done;
        }

        xhci_dbg(xhci, "Endpoint ring:\n");
        xhci_debug_ring(xhci, ep_ring);

        urb_priv = urb->hcpriv;

        for (i = urb_priv->td_cnt; i < urb_priv->length; i++) {
                td = urb_priv->td[i];
                list_add_tail(&td->cancelled_td_list, &ep->cancelled_td_list);
        }

        /* Queue a stop endpoint command, but only if this is
         * the first cancellation to be handled.
         */
        if (!(ep->ep_state & EP_HALT_PENDING)) {
                ep->ep_state |= EP_HALT_PENDING;
                ep->stop_cmds_pending++;
                ep->stop_cmd_timer.expires = jiffies +
                        XHCI_STOP_EP_CMD_TIMEOUT * HZ;
                add_timer(&ep->stop_cmd_timer);
                xhci_queue_stop_endpoint(xhci, urb->dev->slot_id, ep_index, 0);
                xhci_ring_cmd_db(xhci);
        }
done:
        spin_unlock_irqrestore(&xhci->lock, flags);
        return ret;
}

/* Drop an endpoint from a new bandwidth configuration for this device.
 * Only one call to this function is allowed per endpoint before
 * check_bandwidth() or reset_bandwidth() must be called.
 * A call to xhci_drop_endpoint() followed by a call to xhci_add_endpoint() will
 * add the endpoint to the schedule with possibly new parameters denoted by a
 * different endpoint descriptor in usb_host_endpoint.
 * A call to xhci_add_endpoint() followed by a call to xhci_drop_endpoint() is
 * not allowed.
 *
 * The USB core will not allow URBs to be queued to an endpoint that is being
 * disabled, so there's no need for mutual exclusion to protect
 * the xhci->devs[slot_id] structure.
 */
int xhci_drop_endpoint(struct usb_hcd *hcd, struct usb_device *udev,
                struct usb_host_endpoint *ep)
{
        struct xhci_hcd *xhci;
        struct xhci_container_ctx *in_ctx, *out_ctx;
        struct xhci_input_control_ctx *ctrl_ctx;
        struct xhci_slot_ctx *slot_ctx;
        unsigned int last_ctx;
        unsigned int ep_index;
        struct xhci_ep_ctx *ep_ctx;
        u32 drop_flag;
        u32 new_add_flags, new_drop_flags, new_slot_info;
        int ret;

        ret = xhci_check_args(hcd, udev, ep, 1, true, __func__);
        if (ret <= 0)
                return ret;
        xhci = hcd_to_xhci(hcd);
        if (xhci->xhc_state & XHCI_STATE_DYING)
                return -ENODEV;

        xhci_dbg(xhci, "%s called for udev %p\n", __func__, udev);
        drop_flag = xhci_get_endpoint_flag(&ep->desc);
        if (drop_flag == SLOT_FLAG || drop_flag == EP0_FLAG) {
                xhci_dbg(xhci, "xHCI %s - can't drop slot or ep 0 %#x\n",
                                __func__, drop_flag);
                return 0;
        }

        in_ctx = xhci->devs[udev->slot_id]->in_ctx;
        out_ctx = xhci->devs[udev->slot_id]->out_ctx;
        ctrl_ctx = xhci_get_input_control_ctx(xhci, in_ctx);
        ep_index = xhci_get_endpoint_index(&ep->desc);
        ep_ctx = xhci_get_ep_ctx(xhci, out_ctx, ep_index);
        /* If the HC already knows the endpoint is disabled,
         * or the HCD has noted it is disabled, ignore this request
         */
        if ((le32_to_cpu(ep_ctx->ep_info) & EP_STATE_MASK) ==
            EP_STATE_DISABLED ||
            le32_to_cpu(ctrl_ctx->drop_flags) &
            xhci_get_endpoint_flag(&ep->desc)) {
                xhci_warn(xhci, "xHCI %s called with disabled ep %p\n",
                                __func__, ep);
                return 0;
        }

        ctrl_ctx->drop_flags |= cpu_to_le32(drop_flag);
        new_drop_flags = le32_to_cpu(ctrl_ctx->drop_flags);

        ctrl_ctx->add_flags &= cpu_to_le32(~drop_flag);
        new_add_flags = le32_to_cpu(ctrl_ctx->add_flags);

        last_ctx = xhci_last_valid_endpoint(le32_to_cpu(ctrl_ctx->add_flags));
        slot_ctx = xhci_get_slot_ctx(xhci, in_ctx);
        /* Update the last valid endpoint context, if we deleted the last one */
        if ((le32_to_cpu(slot_ctx->dev_info) & LAST_CTX_MASK) >
            LAST_CTX(last_ctx)) {
                slot_ctx->dev_info &= cpu_to_le32(~LAST_CTX_MASK);
                slot_ctx->dev_info |= cpu_to_le32(LAST_CTX(last_ctx));
        }
        new_slot_info = le32_to_cpu(slot_ctx->dev_info);

        xhci_endpoint_zero(xhci, xhci->devs[udev->slot_id], ep);

        xhci_dbg(xhci, "drop ep 0x%x, slot id %d, new drop flags = %#x, new add flags = %#x, new slot info = %#x\n",
                        (unsigned int) ep->desc.bEndpointAddress,
                        udev->slot_id,
                        (unsigned int) new_drop_flags,
                        (unsigned int) new_add_flags,
                        (unsigned int) new_slot_info);
        return 0;
}

/* Add an endpoint to a new possible bandwidth configuration for this device.
 * Only one call to this function is allowed per endpoint before
 * check_bandwidth() or reset_bandwidth() must be called.
 * A call to xhci_drop_endpoint() followed by a call to xhci_add_endpoint() will
 * add the endpoint to the schedule with possibly new parameters denoted by a
 * different endpoint descriptor in usb_host_endpoint.
 * A call to xhci_add_endpoint() followed by a call to xhci_drop_endpoint() is
 * not allowed.
 *
 * The USB core will not allow URBs to be queued to an endpoint until the
 * configuration or alt setting is installed in the device, so there's no need
 * for mutual exclusion to protect the xhci->devs[slot_id] structure.
 */
int xhci_add_endpoint(struct usb_hcd *hcd, struct usb_device *udev,
                struct usb_host_endpoint *ep)
{
        struct xhci_hcd *xhci;
        struct xhci_container_ctx *in_ctx, *out_ctx;
        unsigned int ep_index;
        struct xhci_ep_ctx *ep_ctx;
        struct xhci_slot_ctx *slot_ctx;
        struct xhci_input_control_ctx *ctrl_ctx;
        u32 added_ctxs;
        unsigned int last_ctx;
        u32 new_add_flags, new_drop_flags, new_slot_info;
        struct xhci_virt_device *virt_dev;
        int ret = 0;

        ret = xhci_check_args(hcd, udev, ep, 1, true, __func__);
        if (ret <= 0) {
                /* So we won't queue a reset ep command for a root hub */
                ep->hcpriv = NULL;
                return ret;
        }
        xhci = hcd_to_xhci(hcd);
        if (xhci->xhc_state & XHCI_STATE_DYING)
                return -ENODEV;

        added_ctxs = xhci_get_endpoint_flag(&ep->desc);
        last_ctx = xhci_last_valid_endpoint(added_ctxs);
        if (added_ctxs == SLOT_FLAG || added_ctxs == EP0_FLAG) {
                /* FIXME when we have to issue an evaluate endpoint command to
                 * deal with ep0 max packet size changing once we get the
                 * descriptors
                 */
                xhci_dbg(xhci, "xHCI %s - can't add slot or ep 0 %#x\n",
                                __func__, added_ctxs);
                return 0;
        }

        virt_dev = xhci->devs[udev->slot_id];
        in_ctx = virt_dev->in_ctx;
        out_ctx = virt_dev->out_ctx;
        ctrl_ctx = xhci_get_input_control_ctx(xhci, in_ctx);
        ep_index = xhci_get_endpoint_index(&ep->desc);
        ep_ctx = xhci_get_ep_ctx(xhci, out_ctx, ep_index);

        /* If this endpoint is already in use, and the upper layers are trying
         * to add it again without dropping it, reject the addition.
         */
        if (virt_dev->eps[ep_index].ring &&
                        !(le32_to_cpu(ctrl_ctx->drop_flags) &
                                xhci_get_endpoint_flag(&ep->desc))) {
                xhci_warn(xhci, "Trying to add endpoint 0x%x "
                                "without dropping it.\n",
                                (unsigned int) ep->desc.bEndpointAddress);
                return -EINVAL;
        }

        /* If the HCD has already noted the endpoint is enabled,
         * ignore this request.
         */
        if (le32_to_cpu(ctrl_ctx->add_flags) &
            xhci_get_endpoint_flag(&ep->desc)) {
                xhci_warn(xhci, "xHCI %s called with enabled ep %p\n",
                                __func__, ep);
                return 0;
        }

        /*
         * Configuration and alternate setting changes must be done in
         * process context, not interrupt context (or so documenation
         * for usb_set_interface() and usb_set_configuration() claim).
         */
        if (xhci_endpoint_init(xhci, virt_dev, udev, ep, GFP_NOIO) < 0) {
                dev_dbg(&udev->dev, "%s - could not initialize ep %#x\n",
                                __func__, ep->desc.bEndpointAddress);
                return -ENOMEM;
        }

        ctrl_ctx->add_flags |= cpu_to_le32(added_ctxs);
        new_add_flags = le32_to_cpu(ctrl_ctx->add_flags);

        /* If xhci_endpoint_disable() was called for this endpoint, but the
         * xHC hasn't been notified yet through the check_bandwidth() call,
         * this re-adds a new state for the endpoint from the new endpoint
         * descriptors.  We must drop and re-add this endpoint, so we leave the
         * drop flags alone.
         */
        new_drop_flags = le32_to_cpu(ctrl_ctx->drop_flags);

        slot_ctx = xhci_get_slot_ctx(xhci, in_ctx);
        /* Update the last valid endpoint context, if we just added one past */
        if ((le32_to_cpu(slot_ctx->dev_info) & LAST_CTX_MASK) <
            LAST_CTX(last_ctx)) {
                slot_ctx->dev_info &= cpu_to_le32(~LAST_CTX_MASK);
                slot_ctx->dev_info |= cpu_to_le32(LAST_CTX(last_ctx));
        }
        new_slot_info = le32_to_cpu(slot_ctx->dev_info);

        /* Store the usb_device pointer for later use */
        ep->hcpriv = udev;

        xhci_dbg(xhci, "add ep 0x%x, slot id %d, new drop flags = %#x, new add flags = %#x, new slot info = %#x\n",
                        (unsigned int) ep->desc.bEndpointAddress,
                        udev->slot_id,
                        (unsigned int) new_drop_flags,
                        (unsigned int) new_add_flags,
                        (unsigned int) new_slot_info);
        return 0;
}

static void xhci_zero_in_ctx(struct xhci_hcd *xhci, struct xhci_virt_device *virt_dev)
{
        struct xhci_input_control_ctx *ctrl_ctx;
        struct xhci_ep_ctx *ep_ctx;
        struct xhci_slot_ctx *slot_ctx;
        int i;

        /* When a device's add flag and drop flag are zero, any subsequent
         * configure endpoint command will leave that endpoint's state
         * untouched.  Make sure we don't leave any old state in the input
         * endpoint contexts.
         */
        ctrl_ctx = xhci_get_input_control_ctx(xhci, virt_dev->in_ctx);
        ctrl_ctx->drop_flags = 0;
        ctrl_ctx->add_flags = 0;
        slot_ctx = xhci_get_slot_ctx(xhci, virt_dev->in_ctx);
        slot_ctx->dev_info &= cpu_to_le32(~LAST_CTX_MASK);
        /* Endpoint 0 is always valid */
        slot_ctx->dev_info |= cpu_to_le32(LAST_CTX(1));
        for (i = 1; i < 31; ++i) {
                ep_ctx = xhci_get_ep_ctx(xhci, virt_dev->in_ctx, i);
                ep_ctx->ep_info = 0;
                ep_ctx->ep_info2 = 0;
                ep_ctx->deq = 0;
                ep_ctx->tx_info = 0;
        }
}

static int xhci_configure_endpoint_result(struct xhci_hcd *xhci,
                struct usb_device *udev, u32 *cmd_status)
{
        int ret;

        switch (*cmd_status) {
        case COMP_ENOMEM:
                dev_warn(&udev->dev, "Not enough host controller resources "
                                "for new device state.\n");
                ret = -ENOMEM;
                /* FIXME: can we allocate more resources for the HC? */
                break;
        case COMP_BW_ERR:
                dev_warn(&udev->dev, "Not enough bandwidth "
                                "for new device state.\n");
                ret = -ENOSPC;
                /* FIXME: can we go back to the old state? */
                break;
        case COMP_TRB_ERR:
                /* the HCD set up something wrong */
                dev_warn(&udev->dev, "ERROR: Endpoint drop flag = 0, "
                                "add flag = 1, "
                                "and endpoint is not disabled.\n");
                ret = -EINVAL;
                break;
        case COMP_DEV_ERR:
                dev_warn(&udev->dev, "ERROR: Incompatible device for endpoint "
                                "configure command.\n");
                ret = -ENODEV;
                break;
        case COMP_SUCCESS:
                dev_dbg(&udev->dev, "Successful Endpoint Configure command\n");
                ret = 0;
                break;
        default:
                xhci_err(xhci, "ERROR: unexpected command completion "
                                "code 0x%x.\n", *cmd_status);
                ret = -EINVAL;
                break;
        }
        return ret;
}

static int xhci_evaluate_context_result(struct xhci_hcd *xhci,
                struct usb_device *udev, u32 *cmd_status)
{
        int ret;
        struct xhci_virt_device *virt_dev = xhci->devs[udev->slot_id];

        switch (*cmd_status) {
        case COMP_EINVAL:
                dev_warn(&udev->dev, "WARN: xHCI driver setup invalid evaluate "
                                "context command.\n");
                ret = -EINVAL;
                break;
        case COMP_EBADSLT:
                dev_warn(&udev->dev, "WARN: slot not enabled for"
                                "evaluate context command.\n");
        case COMP_CTX_STATE:
                dev_warn(&udev->dev, "WARN: invalid context state for "
                                "evaluate context command.\n");
                xhci_dbg_ctx(xhci, virt_dev->out_ctx, 1);
                ret = -EINVAL;
                break;
        case COMP_DEV_ERR:
                dev_warn(&udev->dev, "ERROR: Incompatible device for evaluate "
                                "context command.\n");
                ret = -ENODEV;
                break;
        case COMP_MEL_ERR:
                /* Max Exit Latency too large error */
                dev_warn(&udev->dev, "WARN: Max Exit Latency too large\n");
                ret = -EINVAL;
                break;
        case COMP_SUCCESS:
                dev_dbg(&udev->dev, "Successful evaluate context command\n");
                ret = 0;
                break;
        default:
                xhci_err(xhci, "ERROR: unexpected command completion "
                                "code 0x%x.\n", *cmd_status);
                ret = -EINVAL;
                break;
        }
        return ret;
}

static u32 xhci_count_num_new_endpoints(struct xhci_hcd *xhci,
                struct xhci_container_ctx *in_ctx)
{
        struct xhci_input_control_ctx *ctrl_ctx;
        u32 valid_add_flags;
        u32 valid_drop_flags;

        ctrl_ctx = xhci_get_input_control_ctx(xhci, in_ctx);
        /* Ignore the slot flag (bit 0), and the default control endpoint flag
         * (bit 1).  The default control endpoint is added during the Address
         * Device command and is never removed until the slot is disabled.
         */
        valid_add_flags = ctrl_ctx->add_flags >> 2;
        valid_drop_flags = ctrl_ctx->drop_flags >> 2;

        /* Use hweight32 to count the number of ones in the add flags, or
         * number of endpoints added.  Don't count endpoints that are changed
         * (both added and dropped).
         */
        return hweight32(valid_add_flags) -
                hweight32(valid_add_flags & valid_drop_flags);
}

static unsigned int xhci_count_num_dropped_endpoints(struct xhci_hcd *xhci,
                struct xhci_container_ctx *in_ctx)
{
        struct xhci_input_control_ctx *ctrl_ctx;
        u32 valid_add_flags;
        u32 valid_drop_flags;

        ctrl_ctx = xhci_get_input_control_ctx(xhci, in_ctx);
        valid_add_flags = ctrl_ctx->add_flags >> 2;
        valid_drop_flags = ctrl_ctx->drop_flags >> 2;

        return hweight32(valid_drop_flags) -
                hweight32(valid_add_flags & valid_drop_flags);
}

/*
 * We need to reserve the new number of endpoints before the configure endpoint
 * command completes.  We can't subtract the dropped endpoints from the number
 * of active endpoints until the command completes because we can oversubscribe
 * the host in this case:
 *
 *  - the first configure endpoint command drops more endpoints than it adds
 *  - a second configure endpoint command that adds more endpoints is queued
 *  - the first configure endpoint command fails, so the config is unchanged
 *  - the second command may succeed, even though there isn't enough resources
 *
 * Must be called with xhci->lock held.
 */
static int xhci_reserve_host_resources(struct xhci_hcd *xhci,
                struct xhci_container_ctx *in_ctx)
{
        u32 added_eps;

        added_eps = xhci_count_num_new_endpoints(xhci, in_ctx);
        if (xhci->num_active_eps + added_eps > xhci->limit_active_eps) {
                xhci_dbg(xhci, "Not enough ep ctxs: "
                                "%u active, need to add %u, limit is %u.\n",
                                xhci->num_active_eps, added_eps,
                                xhci->limit_active_eps);
                return -ENOMEM;
        }
        xhci->num_active_eps += added_eps;
        xhci_dbg(xhci, "Adding %u ep ctxs, %u now active.\n", added_eps,
                        xhci->num_active_eps);
        return 0;
}

/*
 * The configure endpoint was failed by the xHC for some other reason, so we
 * need to revert the resources that failed configuration would have used.
 *
 * Must be called with xhci->lock held.
 */
static void xhci_free_host_resources(struct xhci_hcd *xhci,
                struct xhci_container_ctx *in_ctx)
{
        u32 num_failed_eps;

        num_failed_eps = xhci_count_num_new_endpoints(xhci, in_ctx);
        xhci->num_active_eps -= num_failed_eps;
        xhci_dbg(xhci, "Removing %u failed ep ctxs, %u now active.\n",
                        num_failed_eps,
                        xhci->num_active_eps);
}

/*
 * Now that the command has completed, clean up the active endpoint count by
 * subtracting out the endpoints that were dropped (but not changed).
 *
 * Must be called with xhci->lock held.
 */
static void xhci_finish_resource_reservation(struct xhci_hcd *xhci,
                struct xhci_container_ctx *in_ctx)
{
        u32 num_dropped_eps;

        num_dropped_eps = xhci_count_num_dropped_endpoints(xhci, in_ctx);
        xhci->num_active_eps -= num_dropped_eps;
        if (num_dropped_eps)
                xhci_dbg(xhci, "Removing %u dropped ep ctxs, %u now active.\n",
                                num_dropped_eps,
                                xhci->num_active_eps);
}

/* Issue a configure endpoint command or evaluate context command
 * and wait for it to finish.
 */
static int xhci_configure_endpoint(struct xhci_hcd *xhci,
                struct usb_device *udev,
                struct xhci_command *command,
                bool ctx_change, bool must_succeed)
{
        int ret;
        int timeleft;
        unsigned long flags;
        struct xhci_container_ctx *in_ctx;
        struct completion *cmd_completion;
        u32 *cmd_status;
        struct xhci_virt_device *virt_dev;

        spin_lock_irqsave(&xhci->lock, flags);
        virt_dev = xhci->devs[udev->slot_id];
        if (command) {
                in_ctx = command->in_ctx;
                if ((xhci->quirks & XHCI_EP_LIMIT_QUIRK) &&
                                xhci_reserve_host_resources(xhci, in_ctx)) {
                        spin_unlock_irqrestore(&xhci->lock, flags);
                        xhci_warn(xhci, "Not enough host resources, "
                                        "active endpoint contexts = %u\n",
                                        xhci->num_active_eps);
                        return -ENOMEM;
                }

                cmd_completion = command->completion;
                cmd_status = &command->status;
                command->command_trb = xhci->cmd_ring->enqueue;

                /* Enqueue pointer can be left pointing to the link TRB,
                 * we must handle that
                 */
                if ((le32_to_cpu(command->command_trb->link.control)
                     & TRB_TYPE_BITMASK) == TRB_TYPE(TRB_LINK))
                        command->command_trb =
                                xhci->cmd_ring->enq_seg->next->trbs;

                list_add_tail(&command->cmd_list, &virt_dev->cmd_list);
        } else {
                in_ctx = virt_dev->in_ctx;
                if ((xhci->quirks & XHCI_EP_LIMIT_QUIRK) &&
                                xhci_reserve_host_resources(xhci, in_ctx)) {
                        spin_unlock_irqrestore(&xhci->lock, flags);
                        xhci_warn(xhci, "Not enough host resources, "
                                        "active endpoint contexts = %u\n",
                                        xhci->num_active_eps);
                        return -ENOMEM;
                }
                cmd_completion = &virt_dev->cmd_completion;
                cmd_status = &virt_dev->cmd_status;
        }
        init_completion(cmd_completion);

        if (!ctx_change)
                ret = xhci_queue_configure_endpoint(xhci, in_ctx->dma,
                                udev->slot_id, must_succeed);
        else
                ret = xhci_queue_evaluate_context(xhci, in_ctx->dma,
                                udev->slot_id);
        if (ret < 0) {
                if (command)
                        list_del(&command->cmd_list);
                if ((xhci->quirks & XHCI_EP_LIMIT_QUIRK))
                        xhci_free_host_resources(xhci, in_ctx);
                spin_unlock_irqrestore(&xhci->lock, flags);
                xhci_dbg(xhci, "FIXME allocate a new ring segment\n");
                return -ENOMEM;
        }
        xhci_ring_cmd_db(xhci);
        spin_unlock_irqrestore(&xhci->lock, flags);

        /* Wait for the configure endpoint command to complete */
        timeleft = wait_for_completion_interruptible_timeout(
                        cmd_completion,
                        USB_CTRL_SET_TIMEOUT);
        if (timeleft <= 0) {
                xhci_warn(xhci, "%s while waiting for %s command\n",
                                timeleft == 0 ? "Timeout" : "Signal",
                                ctx_change == 0 ?
                                        "configure endpoint" :
                                        "evaluate context");
                /* FIXME cancel the configure endpoint command */
                return -ETIME;
        }

        if (!ctx_change)
                ret = xhci_configure_endpoint_result(xhci, udev, cmd_status);
        else
                ret = xhci_evaluate_context_result(xhci, udev, cmd_status);

        if ((xhci->quirks & XHCI_EP_LIMIT_QUIRK)) {
                spin_lock_irqsave(&xhci->lock, flags);
                /* If the command failed, remove the reserved resources.
                 * Otherwise, clean up the estimate to include dropped eps.
                 */
                if (ret)
                        xhci_free_host_resources(xhci, in_ctx);
                else
                        xhci_finish_resource_reservation(xhci, in_ctx);
                spin_unlock_irqrestore(&xhci->lock, flags);
        }
        return ret;
}

/* Called after one or more calls to xhci_add_endpoint() or
 * xhci_drop_endpoint().  If this call fails, the USB core is expected
 * to call xhci_reset_bandwidth().
 *
 * Since we are in the middle of changing either configuration or
 * installing a new alt setting, the USB core won't allow URBs to be
 * enqueued for any endpoint on the old config or interface.  Nothing
 * else should be touching the xhci->devs[slot_id] structure, so we
 * don't need to take the xhci->lock for manipulating that.
 */
int xhci_check_bandwidth(struct usb_hcd *hcd, struct usb_device *udev)
{
        int i;
        int ret = 0;
        struct xhci_hcd *xhci;
        struct xhci_virt_device *virt_dev;
        struct xhci_input_control_ctx *ctrl_ctx;
        struct xhci_slot_ctx *slot_ctx;

        ret = xhci_check_args(hcd, udev, NULL, 0, true, __func__);
        if (ret <= 0)
                return ret;
        xhci = hcd_to_xhci(hcd);
        if (xhci->xhc_state & XHCI_STATE_DYING)
                return -ENODEV;

        xhci_dbg(xhci, "%s called for udev %p\n", __func__, udev);
        virt_dev = xhci->devs[udev->slot_id];

        /* See section 4.6.6 - A0 = 1; A1 = D0 = D1 = 0 */
        ctrl_ctx = xhci_get_input_control_ctx(xhci, virt_dev->in_ctx);
        ctrl_ctx->add_flags |= cpu_to_le32(SLOT_FLAG);
        ctrl_ctx->add_flags &= cpu_to_le32(~EP0_FLAG);
        ctrl_ctx->drop_flags &= cpu_to_le32(~(SLOT_FLAG | EP0_FLAG));
        xhci_dbg(xhci, "New Input Control Context:\n");
        slot_ctx = xhci_get_slot_ctx(xhci, virt_dev->in_ctx);
        xhci_dbg_ctx(xhci, virt_dev->in_ctx,
                     LAST_CTX_TO_EP_NUM(le32_to_cpu(slot_ctx->dev_info)));

        ret = xhci_configure_endpoint(xhci, udev, NULL,
                        false, false);
        if (ret) {
                /* Callee should call reset_bandwidth() */
                return ret;
        }

        xhci_dbg(xhci, "Output context after successful config ep cmd:\n");
        xhci_dbg_ctx(xhci, virt_dev->out_ctx,
                     LAST_CTX_TO_EP_NUM(le32_to_cpu(slot_ctx->dev_info)));

        /* Free any rings that were dropped, but not changed. */
        for (i = 1; i < 31; ++i) {
                if ((le32_to_cpu(ctrl_ctx->drop_flags) & (1 << (i + 1))) &&
                    !(le32_to_cpu(ctrl_ctx->add_flags) & (1 << (i + 1))))
                        xhci_free_or_cache_endpoint_ring(xhci, virt_dev, i);
        }
        xhci_zero_in_ctx(xhci, virt_dev);
        /*
         * Install any rings for completely new endpoints or changed endpoints,
         * and free or cache any old rings from changed endpoints.
         */
        for (i = 1; i < 31; ++i) {
                if (!virt_dev->eps[i].new_ring)
                        continue;
                /* Only cache or free the old ring if it exists.
                 * It may not if this is the first add of an endpoint.
                 */
                if (virt_dev->eps[i].ring) {
                        xhci_free_or_cache_endpoint_ring(xhci, virt_dev, i);
                }
                virt_dev->eps[i].ring = virt_dev->eps[i].new_ring;
                virt_dev->eps[i].new_ring = NULL;
        }

        return ret;
}

void xhci_reset_bandwidth(struct usb_hcd *hcd, struct usb_device *udev)
{
        struct xhci_hcd *xhci;
        struct xhci_virt_device *virt_dev;
        int i, ret;

        ret = xhci_check_args(hcd, udev, NULL, 0, true, __func__);
        if (ret <= 0)
                return;
        xhci = hcd_to_xhci(hcd);

        xhci_dbg(xhci, "%s called for udev %p\n", __func__, udev);
        virt_dev = xhci->devs[udev->slot_id];
        /* Free any rings allocated for added endpoints */
        for (i = 0; i < 31; ++i) {
                if (virt_dev->eps[i].new_ring) {
                        xhci_ring_free(xhci, virt_dev->eps[i].new_ring);
                        virt_dev->eps[i].new_ring = NULL;
                }
        }
        xhci_zero_in_ctx(xhci, virt_dev);
}

static void xhci_setup_input_ctx_for_config_ep(struct xhci_hcd *xhci,
                struct xhci_container_ctx *in_ctx,
                struct xhci_container_ctx *out_ctx,
                u32 add_flags, u32 drop_flags)
{
        struct xhci_input_control_ctx *ctrl_ctx;
        ctrl_ctx = xhci_get_input_control_ctx(xhci, in_ctx);
        ctrl_ctx->add_flags = cpu_to_le32(add_flags);
        ctrl_ctx->drop_flags = cpu_to_le32(drop_flags);
        xhci_slot_copy(xhci, in_ctx, out_ctx);
        ctrl_ctx->add_flags |= cpu_to_le32(SLOT_FLAG);

        xhci_dbg(xhci, "Input Context:\n");
        xhci_dbg_ctx(xhci, in_ctx, xhci_last_valid_endpoint(add_flags));
}

static void xhci_setup_input_ctx_for_quirk(struct xhci_hcd *xhci,
                unsigned int slot_id, unsigned int ep_index,
                struct xhci_dequeue_state *deq_state)
{
        struct xhci_container_ctx *in_ctx;
        struct xhci_ep_ctx *ep_ctx;
        u32 added_ctxs;
        dma_addr_t addr;

        xhci_endpoint_copy(xhci, xhci->devs[slot_id]->in_ctx,
                        xhci->devs[slot_id]->out_ctx, ep_index);
        in_ctx = xhci->devs[slot_id]->in_ctx;
        ep_ctx = xhci_get_ep_ctx(xhci, in_ctx, ep_index);
        addr = xhci_trb_virt_to_dma(deq_state->new_deq_seg,
                        deq_state->new_deq_ptr);
        if (addr == 0) {
                xhci_warn(xhci, "WARN Cannot submit config ep after "
                                "reset ep command\n");
                xhci_warn(xhci, "WARN deq seg = %p, deq ptr = %p\n",
                                deq_state->new_deq_seg,
                                deq_state->new_deq_ptr);
                return;
        }
        ep_ctx->deq = cpu_to_le64(addr | deq_state->new_cycle_state);

        added_ctxs = xhci_get_endpoint_flag_from_index(ep_index);
        xhci_setup_input_ctx_for_config_ep(xhci, xhci->devs[slot_id]->in_ctx,
                        xhci->devs[slot_id]->out_ctx, added_ctxs, added_ctxs);
}

void xhci_cleanup_stalled_ring(struct xhci_hcd *xhci,
                struct usb_device *udev, unsigned int ep_index)
{
        struct xhci_dequeue_state deq_state;
        struct xhci_virt_ep *ep;

        xhci_dbg(xhci, "Cleaning up stalled endpoint ring\n");
        ep = &xhci->devs[udev->slot_id]->eps[ep_index];
        /* We need to move the HW's dequeue pointer past this TD,
         * or it will attempt to resend it on the next doorbell ring.
         */
        xhci_find_new_dequeue_state(xhci, udev->slot_id,
                        ep_index, ep->stopped_stream, ep->stopped_td,
                        &deq_state);

        /* HW with the reset endpoint quirk will use the saved dequeue state to
         * issue a configure endpoint command later.
         */
        if (!(xhci->quirks & XHCI_RESET_EP_QUIRK)) {
                xhci_dbg(xhci, "Queueing new dequeue state\n");
                xhci_queue_new_dequeue_state(xhci, udev->slot_id,
                                ep_index, ep->stopped_stream, &deq_state);
        } else {
                /* Better hope no one uses the input context between now and the
                 * reset endpoint completion!
                 * XXX: No idea how this hardware will react when stream rings
                 * are enabled.
                 */
                xhci_dbg(xhci, "Setting up input context for "
                                "configure endpoint command\n");
                xhci_setup_input_ctx_for_quirk(xhci, udev->slot_id,
                                ep_index, &deq_state);
        }
}

/* Deal with stalled endpoints.  The core should have sent the control message
 * to clear the halt condition.  However, we need to make the xHCI hardware
 * reset its sequence number, since a device will expect a sequence number of
 * zero after the halt condition is cleared.
 * Context: in_interrupt
 */
void xhci_endpoint_reset(struct usb_hcd *hcd,
                struct usb_host_endpoint *ep)
{
        struct xhci_hcd *xhci;
        struct usb_device *udev;
        unsigned int ep_index;
        unsigned long flags;
        int ret;
        struct xhci_virt_ep *virt_ep;

        xhci = hcd_to_xhci(hcd);
        udev = (struct usb_device *) ep->hcpriv;
        /* Called with a root hub endpoint (or an endpoint that wasn't added
         * with xhci_add_endpoint()
         */
        if (!ep->hcpriv)
                return;
        ep_index = xhci_get_endpoint_index(&ep->desc);
        virt_ep = &xhci->devs[udev->slot_id]->eps[ep_index];
        if (!virt_ep->stopped_td) {
                xhci_dbg(xhci, "Endpoint 0x%x not halted, refusing to reset.\n",
                                ep->desc.bEndpointAddress);
                return;
        }
        if (usb_endpoint_xfer_control(&ep->desc)) {
                xhci_dbg(xhci, "Control endpoint stall already handled.\n");
                return;
        }

        xhci_dbg(xhci, "Queueing reset endpoint command\n");
        spin_lock_irqsave(&xhci->lock, flags);
        ret = xhci_queue_reset_ep(xhci, udev->slot_id, ep_index);
        /*
         * Can't change the ring dequeue pointer until it's transitioned to the
         * stopped state, which is only upon a successful reset endpoint
         * command.  Better hope that last command worked!
         */
        if (!ret) {
                xhci_cleanup_stalled_ring(xhci, udev, ep_index);
                kfree(virt_ep->stopped_td);
                xhci_ring_cmd_db(xhci);
        }
        virt_ep->stopped_td = NULL;
        virt_ep->stopped_trb = NULL;
        virt_ep->stopped_stream = 0;
        spin_unlock_irqrestore(&xhci->lock, flags);

        if (ret)
                xhci_warn(xhci, "FIXME allocate a new ring segment\n");
}

static int xhci_check_streams_endpoint(struct xhci_hcd *xhci,
                struct usb_device *udev, struct usb_host_endpoint *ep,
                unsigned int slot_id)
{
        int ret;
        unsigned int ep_index;
        unsigned int ep_state;

        if (!ep)
                return -EINVAL;
        ret = xhci_check_args(xhci_to_hcd(xhci), udev, ep, 1, true, __func__);
        if (ret <= 0)
                return -EINVAL;
        if (ep->ss_ep_comp.bmAttributes == 0) {
                xhci_warn(xhci, "WARN: SuperSpeed Endpoint Companion"
                                " descriptor for ep 0x%x does not support streams\n",
                                ep->desc.bEndpointAddress);
                return -EINVAL;
        }

        ep_index = xhci_get_endpoint_index(&ep->desc);
        ep_state = xhci->devs[slot_id]->eps[ep_index].ep_state;
        if (ep_state & EP_HAS_STREAMS ||
                        ep_state & EP_GETTING_STREAMS) {
                xhci_warn(xhci, "WARN: SuperSpeed bulk endpoint 0x%x "
                                "already has streams set up.\n",
                                ep->desc.bEndpointAddress);
                xhci_warn(xhci, "Send email to xHCI maintainer and ask for "
                                "dynamic stream context array reallocation.\n");
                return -EINVAL;
        }
        if (!list_empty(&xhci->devs[slot_id]->eps[ep_index].ring->td_list)) {
                xhci_warn(xhci, "Cannot setup streams for SuperSpeed bulk "
                                "endpoint 0x%x; URBs are pending.\n",
                                ep->desc.bEndpointAddress);
                return -EINVAL;
        }
        return 0;
}

static void xhci_calculate_streams_entries(struct xhci_hcd *xhci,
                unsigned int *num_streams, unsigned int *num_stream_ctxs)
{
        unsigned int max_streams;

        /* The stream context array size must be a power of two */
        *num_stream_ctxs = roundup_pow_of_two(*num_streams);
        /*
         * Find out how many primary stream array entries the host controller
         * supports.  Later we may use secondary stream arrays (similar to 2nd
         * level page entries), but that's an optional feature for xHCI host
         * controllers. xHCs must support at least 4 stream IDs.
         */
        max_streams = HCC_MAX_PSA(xhci->hcc_params);
        if (*num_stream_ctxs > max_streams) {
                xhci_dbg(xhci, "xHCI HW only supports %u stream ctx entries.\n",
                                max_streams);
                *num_stream_ctxs = max_streams;
                *num_streams = max_streams;
        }
}

/* Returns an error code if one of the endpoint already has streams.
 * This does not change any data structures, it only checks and gathers
 * information.
 */
static int xhci_calculate_streams_and_bitmask(struct xhci_hcd *xhci,
                struct usb_device *udev,
                struct usb_host_endpoint **eps, unsigned int num_eps,
                unsigned int *num_streams, u32 *changed_ep_bitmask)
{
        unsigned int max_streams;
        unsigned int endpoint_flag;
        int i;
        int ret;

        for (i = 0; i < num_eps; i++) {
                ret = xhci_check_streams_endpoint(xhci, udev,
                                eps[i], udev->slot_id);
                if (ret < 0)
                        return ret;

                max_streams = USB_SS_MAX_STREAMS(
                                eps[i]->ss_ep_comp.bmAttributes);
                if (max_streams < (*num_streams - 1)) {
                        xhci_dbg(xhci, "Ep 0x%x only supports %u stream IDs.\n",
                                        eps[i]->desc.bEndpointAddress,
                                        max_streams);
                        *num_streams = max_streams+1;
                }

                endpoint_flag = xhci_get_endpoint_flag(&eps[i]->desc);
                if (*changed_ep_bitmask & endpoint_flag)
                        return -EINVAL;
                *changed_ep_bitmask |= endpoint_flag;
        }
        return 0;
}

static u32 xhci_calculate_no_streams_bitmask(struct xhci_hcd *xhci,
                struct usb_device *udev,
                struct usb_host_endpoint **eps, unsigned int num_eps)
{
        u32 changed_ep_bitmask = 0;
        unsigned int slot_id;
        unsigned int ep_index;
        unsigned int ep_state;
        int i;

        slot_id = udev->slot_id;
        if (!xhci->devs[slot_id])
                return 0;

        for (i = 0; i < num_eps; i++) {
                ep_index = xhci_get_endpoint_index(&eps[i]->desc);
                ep_state = xhci->devs[slot_id]->eps[ep_index].ep_state;
                /* Are streams already being freed for the endpoint? */
                if (ep_state & EP_GETTING_NO_STREAMS) {
                        xhci_warn(xhci, "WARN Can't disable streams for "
                                        "endpoint 0x%x\n, "
                                        "streams are being disabled already.",
                                        eps[i]->desc.bEndpointAddress);
                        return 0;
                }
                /* Are there actually any streams to free? */
                if (!(ep_state & EP_HAS_STREAMS) &&
                                !(ep_state & EP_GETTING_STREAMS)) {
                        xhci_warn(xhci, "WARN Can't disable streams for "
                                        "endpoint 0x%x\n, "
                                        "streams are already disabled!",
                                        eps[i]->desc.bEndpointAddress);
                        xhci_warn(xhci, "WARN xhci_free_streams() called "
                                        "with non-streams endpoint\n");
                        return 0;
                }
                changed_ep_bitmask |= xhci_get_endpoint_flag(&eps[i]->desc);
        }
        return changed_ep_bitmask;
}

/*
 * The USB device drivers use this function (though the HCD interface in USB
 * core) to prepare a set of bulk endpoints to use streams.  Streams are used to
 * coordinate mass storage command queueing across multiple endpoints (basically
 * a stream ID == a task ID).
 *
 * Setting up streams involves allocating the same size stream context array
 * for each endpoint and issuing a configure endpoint command for all endpoints.
 *
 * Don't allow the call to succeed if one endpoint only supports one stream
 * (which means it doesn't support streams at all).
 *
 * Drivers may get less stream IDs than they asked for, if the host controller
 * hardware or endpoints claim they can't support the number of requested
 * stream IDs.
 */
int xhci_alloc_streams(struct usb_hcd *hcd, struct usb_device *udev,
                struct usb_host_endpoint **eps, unsigned int num_eps,
                unsigned int num_streams, gfp_t mem_flags)
{
        int i, ret;
        struct xhci_hcd *xhci;
        struct xhci_virt_device *vdev;
        struct xhci_command *config_cmd;
        unsigned int ep_index;
        unsigned int num_stream_ctxs;
        unsigned long flags;
        u32 changed_ep_bitmask = 0;

        if (!eps)
                return -EINVAL;

        /* Add one to the number of streams requested to account for
         * stream 0 that is reserved for xHCI usage.
         */
        num_streams += 1;
        xhci = hcd_to_xhci(hcd);
        xhci_dbg(xhci, "Driver wants %u stream IDs (including stream 0).\n",
                        num_streams);

        config_cmd = xhci_alloc_command(xhci, true, true, mem_flags);
        if (!config_cmd) {
                xhci_dbg(xhci, "Could not allocate xHCI command structure.\n");
                return -ENOMEM;
        }

        /* Check to make sure all endpoints are not already configured for
         * streams.  While we're at it, find the maximum number of streams that
         * all the endpoints will support and check for duplicate endpoints.
         */
        spin_lock_irqsave(&xhci->lock, flags);
        ret = xhci_calculate_streams_and_bitmask(xhci, udev, eps,
                        num_eps, &num_streams, &changed_ep_bitmask);
        if (ret < 0) {
                xhci_free_command(xhci, config_cmd);
                spin_unlock_irqrestore(&xhci->lock, flags);
                return ret;
        }
        if (num_streams <= 1) {
                xhci_warn(xhci, "WARN: endpoints can't handle "
                                "more than one stream.\n");
                xhci_free_command(xhci, config_cmd);
                spin_unlock_irqrestore(&xhci->lock, flags);
                return -EINVAL;
        }
        vdev = xhci->devs[udev->slot_id];
        /* Mark each endpoint as being in transition, so
         * xhci_urb_enqueue() will reject all URBs.
         */
        for (i = 0; i < num_eps; i++) {
                ep_index = xhci_get_endpoint_index(&eps[i]->desc);
                vdev->eps[ep_index].ep_state |= EP_GETTING_STREAMS;
        }
        spin_unlock_irqrestore(&xhci->lock, flags);

        /* Setup internal data structures and allocate HW data structures for
         * streams (but don't install the HW structures in the input context
         * until we're sure all memory allocation succeeded).
         */
        xhci_calculate_streams_entries(xhci, &num_streams, &num_stream_ctxs);
        xhci_dbg(xhci, "Need %u stream ctx entries for %u stream IDs.\n",
                        num_stream_ctxs, num_streams);

        for (i = 0; i < num_eps; i++) {
                ep_index = xhci_get_endpoint_index(&eps[i]->desc);
                vdev->eps[ep_index].stream_info = xhci_alloc_stream_info(xhci,
                                num_stream_ctxs,
                                num_streams, mem_flags);
                if (!vdev->eps[ep_index].stream_info)
                        goto cleanup;
                /* Set maxPstreams in endpoint context and update deq ptr to
                 * point to stream context array. FIXME
                 */
        }

        /* Set up the input context for a configure endpoint command. */
        for (i = 0; i < num_eps; i++) {
                struct xhci_ep_ctx *ep_ctx;

                ep_index = xhci_get_endpoint_index(&eps[i]->desc);
                ep_ctx = xhci_get_ep_ctx(xhci, config_cmd->in_ctx, ep_index);

                xhci_endpoint_copy(xhci, config_cmd->in_ctx,
                                vdev->out_ctx, ep_index);
                xhci_setup_streams_ep_input_ctx(xhci, ep_ctx,
                                vdev->eps[ep_index].stream_info);
        }
        /* Tell the HW to drop its old copy of the endpoint context info
         * and add the updated copy from the input context.
         */
        xhci_setup_input_ctx_for_config_ep(xhci, config_cmd->in_ctx,
                        vdev->out_ctx, changed_ep_bitmask, changed_ep_bitmask);

        /* Issue and wait for the configure endpoint command */
        ret = xhci_configure_endpoint(xhci, udev, config_cmd,
                        false, false);

        /* xHC rejected the configure endpoint command for some reason, so we
         * leave the old ring intact and free our internal streams data
         * structure.
         */
        if (ret < 0)
                goto cleanup;

        spin_lock_irqsave(&xhci->lock, flags);
        for (i = 0; i < num_eps; i++) {
                ep_index = xhci_get_endpoint_index(&eps[i]->desc);
                vdev->eps[ep_index].ep_state &= ~EP_GETTING_STREAMS;
                xhci_dbg(xhci, "Slot %u ep ctx %u now has streams.\n",
                         udev->slot_id, ep_index);
                vdev->eps[ep_index].ep_state |= EP_HAS_STREAMS;
        }
        xhci_free_command(xhci, config_cmd);
        spin_unlock_irqrestore(&xhci->lock, flags);

        /* Subtract 1 for stream 0, which drivers can't use */
        return num_streams - 1;

cleanup:
        /* If it didn't work, free the streams! */
        for (i = 0; i < num_eps; i++) {
                ep_index = xhci_get_endpoint_index(&eps[i]->desc);
                xhci_free_stream_info(xhci, vdev->eps[ep_index].stream_info);
                vdev->eps[ep_index].stream_info = NULL;
                /* FIXME Unset maxPstreams in endpoint context and
                 * update deq ptr to point to normal string ring.
                 */
                vdev->eps[ep_index].ep_state &= ~EP_GETTING_STREAMS;
                vdev->eps[ep_index].ep_state &= ~EP_HAS_STREAMS;
                xhci_endpoint_zero(xhci, vdev, eps[i]);
        }
        xhci_free_command(xhci, config_cmd);
        return -ENOMEM;
}

/* Transition the endpoint from using streams to being a "normal" endpoint
 * without streams.
 *
 * Modify the endpoint context state, submit a configure endpoint command,
 * and free all endpoint rings for streams if that completes successfully.
 */
int xhci_free_streams(struct usb_hcd *hcd, struct usb_device *udev,
                struct usb_host_endpoint **eps, unsigned int num_eps,
                gfp_t mem_flags)
{
        int i, ret;
        struct xhci_hcd *xhci;
        struct xhci_virt_device *vdev;
        struct xhci_command *command;
        unsigned int ep_index;
        unsigned long flags;
        u32 changed_ep_bitmask;

        xhci = hcd_to_xhci(hcd);
        vdev = xhci->devs[udev->slot_id];

        /* Set up a configure endpoint command to remove the streams rings */
        spin_lock_irqsave(&xhci->lock, flags);
        changed_ep_bitmask = xhci_calculate_no_streams_bitmask(xhci,
                        udev, eps, num_eps);
        if (changed_ep_bitmask == 0) {
                spin_unlock_irqrestore(&xhci->lock, flags);
                return -EINVAL;
        }

        /* Use the xhci_command structure from the first endpoint.  We may have
         * allocated too many, but the driver may call xhci_free_streams() for
         * each endpoint it grouped into one call to xhci_alloc_streams().
         */
        ep_index = xhci_get_endpoint_index(&eps[0]->desc);
        command = vdev->eps[ep_index].stream_info->free_streams_command;
        for (i = 0; i < num_eps; i++) {
                struct xhci_ep_ctx *ep_ctx;

                ep_index = xhci_get_endpoint_index(&eps[i]->desc);
                ep_ctx = xhci_get_ep_ctx(xhci, command->in_ctx, ep_index);
                xhci->devs[udev->slot_id]->eps[ep_index].ep_state |=
                        EP_GETTING_NO_STREAMS;

                xhci_endpoint_copy(xhci, command->in_ctx,
                                vdev->out_ctx, ep_index);
                xhci_setup_no_streams_ep_input_ctx(xhci, ep_ctx,
                                &vdev->eps[ep_index]);
        }
        xhci_setup_input_ctx_for_config_ep(xhci, command->in_ctx,
                        vdev->out_ctx, changed_ep_bitmask, changed_ep_bitmask);
        spin_unlock_irqrestore(&xhci->lock, flags);

        /* Issue and wait for the configure endpoint command,
         * which must succeed.
         */
        ret = xhci_configure_endpoint(xhci, udev, command,
                        false, true);

        /* xHC rejected the configure endpoint command for some reason, so we
         * leave the streams rings intact.
         */
        if (ret < 0)
                return ret;

        spin_lock_irqsave(&xhci->lock, flags);
        for (i = 0; i < num_eps; i++) {
                ep_index = xhci_get_endpoint_index(&eps[i]->desc);
                xhci_free_stream_info(xhci, vdev->eps[ep_index].stream_info);
                vdev->eps[ep_index].stream_info = NULL;
                /* FIXME Unset maxPstreams in endpoint context and
                 * update deq ptr to point to normal string ring.
                 */
                vdev->eps[ep_index].ep_state &= ~EP_GETTING_NO_STREAMS;
                vdev->eps[ep_index].ep_state &= ~EP_HAS_STREAMS;
        }
        spin_unlock_irqrestore(&xhci->lock, flags);

        return 0;
}

/*
 * Deletes endpoint resources for endpoints that were active before a Reset
 * Device command, or a Disable Slot command.  The Reset Device command leaves
 * the control endpoint intact, whereas the Disable Slot command deletes it.
 *
 * Must be called with xhci->lock held.
 */
void xhci_free_device_endpoint_resources(struct xhci_hcd *xhci,
        struct xhci_virt_device *virt_dev, bool drop_control_ep)
{
        int i;
        unsigned int num_dropped_eps = 0;
        unsigned int drop_flags = 0;

        for (i = (drop_control_ep ? 0 : 1); i < 31; i++) {
                if (virt_dev->eps[i].ring) {
                        drop_flags |= 1 << i;
                        num_dropped_eps++;
                }
        }
        xhci->num_active_eps -= num_dropped_eps;
        if (num_dropped_eps)
                xhci_dbg(xhci, "Dropped %u ep ctxs, flags = 0x%x, "
                                "%u now active.\n",
                                num_dropped_eps, drop_flags,
                                xhci->num_active_eps);
}

/*
 * This submits a Reset Device Command, which will set the device state to 0,
 * set the device address to 0, and disable all the endpoints except the default
 * control endpoint.  The USB core should come back and call
 * xhci_address_device(), and then re-set up the configuration.  If this is
 * called because of a usb_reset_and_verify_device(), then the old alternate
 * settings will be re-installed through the normal bandwidth allocation
 * functions.
 *
 * Wait for the Reset Device command to finish.  Remove all structures
 * associated with the endpoints that were disabled.  Clear the input device
 * structure?  Cache the rings?  Reset the control endpoint 0 max packet size?
 *
 * If the virt_dev to be reset does not exist or does not match the udev,
 * it means the device is lost, possibly due to the xHC restore error and
 * re-initialization during S3/S4. In this case, call xhci_alloc_dev() to
 * re-allocate the device.
 */
int xhci_discover_or_reset_device(struct usb_hcd *hcd, struct usb_device *udev)
{
        int ret, i;
        unsigned long flags;
        struct xhci_hcd *xhci;
        unsigned int slot_id;
        struct xhci_virt_device *virt_dev;
        struct xhci_command *reset_device_cmd;
        int timeleft;
        int last_freed_endpoint;
        struct xhci_slot_ctx *slot_ctx;

        ret = xhci_check_args(hcd, udev, NULL, 0, false, __func__);
        if (ret <= 0)
                return ret;
        xhci = hcd_to_xhci(hcd);
        slot_id = udev->slot_id;
        virt_dev = xhci->devs[slot_id];
        if (!virt_dev) {
                xhci_dbg(xhci, "The device to be reset with slot ID %u does "
                                "not exist. Re-allocate the device\n", slot_id);
                ret = xhci_alloc_dev(hcd, udev);
                if (ret == 1)
                        return 0;
                else
                        return -EINVAL;
        }

        if (virt_dev->udev != udev) {
                /* If the virt_dev and the udev does not match, this virt_dev
                 * may belong to another udev.
                 * Re-allocate the device.
                 */
                xhci_dbg(xhci, "The device to be reset with slot ID %u does "
                                "not match the udev. Re-allocate the device\n",
                                slot_id);
                ret = xhci_alloc_dev(hcd, udev);
                if (ret == 1)
                        return 0;
                else
                        return -EINVAL;
        }

        /* If device is not setup, there is no point in resetting it */
        slot_ctx = xhci_get_slot_ctx(xhci, virt_dev->out_ctx);
        if (GET_SLOT_STATE(le32_to_cpu(slot_ctx->dev_state)) ==
                                                SLOT_STATE_DISABLED)
                return 0;

        xhci_dbg(xhci, "Resetting device with slot ID %u\n", slot_id);
        /* Allocate the command structure that holds the struct completion.
         * Assume we're in process context, since the normal device reset
         * process has to wait for the device anyway.  Storage devices are
         * reset as part of error handling, so use GFP_NOIO instead of
         * GFP_KERNEL.
         */
        reset_device_cmd = xhci_alloc_command(xhci, false, true, GFP_NOIO);
        if (!reset_device_cmd) {
                xhci_dbg(xhci, "Couldn't allocate command structure.\n");
                return -ENOMEM;
        }

        /* Attempt to submit the Reset Device command to the command ring */
        spin_lock_irqsave(&xhci->lock, flags);
        reset_device_cmd->command_trb = xhci->cmd_ring->enqueue;

        /* Enqueue pointer can be left pointing to the link TRB,
         * we must handle that
         */
        if ((le32_to_cpu(reset_device_cmd->command_trb->link.control)
             & TRB_TYPE_BITMASK) == TRB_TYPE(TRB_LINK))
                reset_device_cmd->command_trb =
                        xhci->cmd_ring->enq_seg->next->trbs;

        list_add_tail(&reset_device_cmd->cmd_list, &virt_dev->cmd_list);
        ret = xhci_queue_reset_device(xhci, slot_id);
        if (ret) {
                xhci_dbg(xhci, "FIXME: allocate a command ring segment\n");
                list_del(&reset_device_cmd->cmd_list);
                spin_unlock_irqrestore(&xhci->lock, flags);
                goto command_cleanup;
        }
        xhci_ring_cmd_db(xhci);
        spin_unlock_irqrestore(&xhci->lock, flags);

        /* Wait for the Reset Device command to finish */
        timeleft = wait_for_completion_interruptible_timeout(
                        reset_device_cmd->completion,
                        USB_CTRL_SET_TIMEOUT);
        if (timeleft <= 0) {
                xhci_warn(xhci, "%s while waiting for reset device command\n",
                                timeleft == 0 ? "Timeout" : "Signal");
                spin_lock_irqsave(&xhci->lock, flags);
                /* The timeout might have raced with the event ring handler, so
                 * only delete from the list if the item isn't poisoned.
                 */
                if (reset_device_cmd->cmd_list.next != LIST_POISON1)
                        list_del(&reset_device_cmd->cmd_list);
                spin_unlock_irqrestore(&xhci->lock, flags);
                ret = -ETIME;
                goto command_cleanup;
        }

        /* The Reset Device command can't fail, according to the 0.95/0.96 spec,
         * unless we tried to reset a slot ID that wasn't enabled,
         * or the device wasn't in the addressed or configured state.
         */
        ret = reset_device_cmd->status;
        switch (ret) {
        case COMP_EBADSLT: /* 0.95 completion code for bad slot ID */
        case COMP_CTX_STATE: /* 0.96 completion code for same thing */
                xhci_info(xhci, "Can't reset device (slot ID %u) in %s state\n",
                                slot_id,
                                xhci_get_slot_state(xhci, virt_dev->out_ctx));
                xhci_info(xhci, "Not freeing device rings.\n");
                /* Don't treat this as an error.  May change my mind later. */
                ret = 0;
                goto command_cleanup;
        case COMP_SUCCESS:
                xhci_dbg(xhci, "Successful reset device command.\n");
                break;
        default:
                if (xhci_is_vendor_info_code(xhci, ret))
                        break;
                xhci_warn(xhci, "Unknown completion code %u for "
                                "reset device command.\n", ret);
                ret = -EINVAL;
                goto command_cleanup;
        }

        /* Free up host controller endpoint resources */
        if ((xhci->quirks & XHCI_EP_LIMIT_QUIRK)) {
                spin_lock_irqsave(&xhci->lock, flags);
                /* Don't delete the default control endpoint resources */
                xhci_free_device_endpoint_resources(xhci, virt_dev, false);
                spin_unlock_irqrestore(&xhci->lock, flags);
        }

        /* Everything but endpoint 0 is disabled, so free or cache the rings. */
        last_freed_endpoint = 1;
        for (i = 1; i < 31; ++i) {
                struct xhci_virt_ep *ep = &virt_dev->eps[i];

                if (ep->ep_state & EP_HAS_STREAMS) {
                        xhci_free_stream_info(xhci, ep->stream_info);
                        ep->stream_info = NULL;
                        ep->ep_state &= ~EP_HAS_STREAMS;
                }

                if (ep->ring) {
                        xhci_free_or_cache_endpoint_ring(xhci, virt_dev, i);
                        last_freed_endpoint = i;
                }
        }
        xhci_dbg(xhci, "Output context after successful reset device cmd:\n");
        xhci_dbg_ctx(xhci, virt_dev->out_ctx, last_freed_endpoint);
        ret = 0;

command_cleanup:
        xhci_free_command(xhci, reset_device_cmd);
        return ret;
}

/*
 * At this point, the struct usb_device is about to go away, the device has
 * disconnected, and all traffic has been stopped and the endpoints have been
 * disabled.  Free any HC data structures associated with that device.
 */
void xhci_free_dev(struct usb_hcd *hcd, struct usb_device *udev)
{
        struct xhci_hcd *xhci = hcd_to_xhci(hcd);
        struct xhci_virt_device *virt_dev;
        unsigned long flags;
        u32 state;
        int i, ret;

        ret = xhci_check_args(hcd, udev, NULL, 0, true, __func__);
        if (ret <= 0)
                return;

        virt_dev = xhci->devs[udev->slot_id];

        /* Stop any wayward timer functions (which may grab the lock) */
        for (i = 0; i < 31; ++i) {
                virt_dev->eps[i].ep_state &= ~EP_HALT_PENDING;
                del_timer_sync(&virt_dev->eps[i].stop_cmd_timer);
        }

        spin_lock_irqsave(&xhci->lock, flags);
        /* Don't disable the slot if the host controller is dead. */
        state = xhci_readl(xhci, &xhci->op_regs->status);
        if (state == 0xffffffff || (xhci->xhc_state & XHCI_STATE_DYING)) {
                xhci_free_virt_device(xhci, udev->slot_id);
                spin_unlock_irqrestore(&xhci->lock, flags);
                return;
        }

        if (xhci_queue_slot_control(xhci, TRB_DISABLE_SLOT, udev->slot_id)) {
                spin_unlock_irqrestore(&xhci->lock, flags);
                xhci_dbg(xhci, "FIXME: allocate a command ring segment\n");
                return;
        }
        xhci_ring_cmd_db(xhci);
        spin_unlock_irqrestore(&xhci->lock, flags);
        /*
         * Event command completion handler will free any data structures
         * associated with the slot.  XXX Can free sleep?
         */
}

/*
 * Checks if we have enough host controller resources for the default control
 * endpoint.
 *
 * Must be called with xhci->lock held.
 */
static int xhci_reserve_host_control_ep_resources(struct xhci_hcd *xhci)
{
        if (xhci->num_active_eps + 1 > xhci->limit_active_eps) {
                xhci_dbg(xhci, "Not enough ep ctxs: "
                                "%u active, need to add 1, limit is %u.\n",
                                xhci->num_active_eps, xhci->limit_active_eps);
                return -ENOMEM;
        }
        xhci->num_active_eps += 1;
        xhci_dbg(xhci, "Adding 1 ep ctx, %u now active.\n",
                        xhci->num_active_eps);
        return 0;
}


/*
 * Returns 0 if the xHC ran out of device slots, the Enable Slot command
 * timed out, or allocating memory failed.  Returns 1 on success.
 */
int xhci_alloc_dev(struct usb_hcd *hcd, struct usb_device *udev)
{
        struct xhci_hcd *xhci = hcd_to_xhci(hcd);
        unsigned long flags;
        int timeleft;
        int ret;

        spin_lock_irqsave(&xhci->lock, flags);
        ret = xhci_queue_slot_control(xhci, TRB_ENABLE_SLOT, 0);
        if (ret) {
                spin_unlock_irqrestore(&xhci->lock, flags);
                xhci_dbg(xhci, "FIXME: allocate a command ring segment\n");
                return 0;
        }
        xhci_ring_cmd_db(xhci);
        spin_unlock_irqrestore(&xhci->lock, flags);

        /* XXX: how much time for xHC slot assignment? */
        timeleft = wait_for_completion_interruptible_timeout(&xhci->addr_dev,
                        USB_CTRL_SET_TIMEOUT);
        if (timeleft <= 0) {
                xhci_warn(xhci, "%s while waiting for a slot\n",
                                timeleft == 0 ? "Timeout" : "Signal");
                /* FIXME cancel the enable slot request */
                return 0;
        }

        if (!xhci->slot_id) {
                xhci_err(xhci, "Error while assigning device slot ID\n");
                return 0;
        }

        if ((xhci->quirks & XHCI_EP_LIMIT_QUIRK)) {
                spin_lock_irqsave(&xhci->lock, flags);
                ret = xhci_reserve_host_control_ep_resources(xhci);
                if (ret) {
                        spin_unlock_irqrestore(&xhci->lock, flags);
                        xhci_warn(xhci, "Not enough host resources, "
                                        "active endpoint contexts = %u\n",
                                        xhci->num_active_eps);
                        goto disable_slot;
                }
                spin_unlock_irqrestore(&xhci->lock, flags);
        }
        /* Use GFP_NOIO, since this function can be called from
         * xhci_discover_or_reset_device(), which may be called as part of
         * mass storage driver error handling.
         */
        if (!xhci_alloc_virt_device(xhci, xhci->slot_id, udev, GFP_NOIO)) {
                xhci_warn(xhci, "Could not allocate xHCI USB device data structures\n");
                goto disable_slot;
        }
        udev->slot_id = xhci->slot_id;
        /* Is this a LS or FS device under a HS hub? */
        /* Hub or peripherial? */
        return 1;

disable_slot:
        /* Disable slot, if we can do it without mem alloc */
        spin_lock_irqsave(&xhci->lock, flags);
        if (!xhci_queue_slot_control(xhci, TRB_DISABLE_SLOT, udev->slot_id))
                xhci_ring_cmd_db(xhci);
        spin_unlock_irqrestore(&xhci->lock, flags);
        return 0;
}

/*
 * Issue an Address Device command (which will issue a SetAddress request to
 * the device).
 * We should be protected by the usb_address0_mutex in khubd's hub_port_init, so
 * we should only issue and wait on one address command at the same time.
 *
 * We add one to the device address issued by the hardware because the USB core
 * uses address 1 for the root hubs (even though they're not really devices).
 */
int xhci_address_device(struct usb_hcd *hcd, struct usb_device *udev)
{
        unsigned long flags;
        int timeleft;
        struct xhci_virt_device *virt_dev;
        int ret = 0;
        struct xhci_hcd *xhci = hcd_to_xhci(hcd);
        struct xhci_slot_ctx *slot_ctx;
        struct xhci_input_control_ctx *ctrl_ctx;
        u64 temp_64;

        if (!udev->slot_id) {
                xhci_dbg(xhci, "Bad Slot ID %d\n", udev->slot_id);
                return -EINVAL;
        }

        virt_dev = xhci->devs[udev->slot_id];

        if (WARN_ON(!virt_dev)) {
                /*
                 * In plug/unplug torture test with an NEC controller,
                 * a zero-dereference was observed once due to virt_dev = 0.
                 * Print useful debug rather than crash if it is observed again!
                 */
                xhci_warn(xhci, "Virt dev invalid for slot_id 0x%x!\n",
                        udev->slot_id);
                return -EINVAL;
        }

        slot_ctx = xhci_get_slot_ctx(xhci, virt_dev->in_ctx);
        /*
         * If this is the first Set Address since device plug-in or
         * virt_device realloaction after a resume with an xHCI power loss,
         * then set up the slot context.
         */
        if (!slot_ctx->dev_info)
                xhci_setup_addressable_virt_dev(xhci, udev);
        /* Otherwise, update the control endpoint ring enqueue pointer. */
        else
                xhci_copy_ep0_dequeue_into_input_ctx(xhci, udev);
        xhci_dbg(xhci, "Slot ID %d Input Context:\n", udev->slot_id);
        xhci_dbg_ctx(xhci, virt_dev->in_ctx, 2);

        spin_lock_irqsave(&xhci->lock, flags);
        ret = xhci_queue_address_device(xhci, virt_dev->in_ctx->dma,
                                        udev->slot_id);
        if (ret) {
                spin_unlock_irqrestore(&xhci->lock, flags);
                xhci_dbg(xhci, "FIXME: allocate a command ring segment\n");
                return ret;
        }
        xhci_ring_cmd_db(xhci);
        spin_unlock_irqrestore(&xhci->lock, flags);

        /* ctrl tx can take up to 5 sec; XXX: need more time for xHC? */
        timeleft = wait_for_completion_interruptible_timeout(&xhci->addr_dev,
                        USB_CTRL_SET_TIMEOUT);
        /* FIXME: From section 4.3.4: "Software shall be responsible for timing
         * the SetAddress() "recovery interval" required by USB and aborting the
         * command on a timeout.
         */
        if (timeleft <= 0) {
                xhci_warn(xhci, "%s while waiting for a slot\n",
                                timeleft == 0 ? "Timeout" : "Signal");
                /* FIXME cancel the address device command */
                return -ETIME;
        }

        switch (virt_dev->cmd_status) {
        case COMP_CTX_STATE:
        case COMP_EBADSLT:
                xhci_err(xhci, "Setup ERROR: address device command for slot %d.\n",
                                udev->slot_id);
                ret = -EINVAL;
                break;
        case COMP_TX_ERR:
                dev_warn(&udev->dev, "Device not responding to set address.\n");
                ret = -EPROTO;
                break;
        case COMP_DEV_ERR:
                dev_warn(&udev->dev, "ERROR: Incompatible device for address "
                                "device command.\n");
                ret = -ENODEV;
                break;
        case COMP_SUCCESS:
                xhci_dbg(xhci, "Successful Address Device command\n");
                break;
        default:
                xhci_err(xhci, "ERROR: unexpected command completion "
                                "code 0x%x.\n", virt_dev->cmd_status);
                xhci_dbg(xhci, "Slot ID %d Output Context:\n", udev->slot_id);
                xhci_dbg_ctx(xhci, virt_dev->out_ctx, 2);
                ret = -EINVAL;
                break;
        }
        if (ret) {
                return ret;
        }
        temp_64 = xhci_read_64(xhci, &xhci->op_regs->dcbaa_ptr);
        xhci_dbg(xhci, "Op regs DCBAA ptr = %#016llx\n", temp_64);
        xhci_dbg(xhci, "Slot ID %d dcbaa entry @%p = %#016llx\n",
                 udev->slot_id,
                 &xhci->dcbaa->dev_context_ptrs[udev->slot_id],
                 (unsigned long long)
                 le64_to_cpu(xhci->dcbaa->dev_context_ptrs[udev->slot_id]));
        xhci_dbg(xhci, "Output Context DMA address = %#08llx\n",
                        (unsigned long long)virt_dev->out_ctx->dma);
        xhci_dbg(xhci, "Slot ID %d Input Context:\n", udev->slot_id);
        xhci_dbg_ctx(xhci, virt_dev->in_ctx, 2);
        xhci_dbg(xhci, "Slot ID %d Output Context:\n", udev->slot_id);
        xhci_dbg_ctx(xhci, virt_dev->out_ctx, 2);
        /*
         * USB core uses address 1 for the roothubs, so we add one to the
         * address given back to us by the HC.
         */
        slot_ctx = xhci_get_slot_ctx(xhci, virt_dev->out_ctx);
        /* Use kernel assigned address for devices; store xHC assigned
         * address locally. */
        virt_dev->address = (le32_to_cpu(slot_ctx->dev_state) & DEV_ADDR_MASK)
                + 1;
        /* Zero the input context control for later use */
        ctrl_ctx = xhci_get_input_control_ctx(xhci, virt_dev->in_ctx);
        ctrl_ctx->add_flags = 0;
        ctrl_ctx->drop_flags = 0;

        xhci_dbg(xhci, "Internal device address = %d\n", virt_dev->address);

        return 0;
}

/* Once a hub descriptor is fetched for a device, we need to update the xHC's
 * internal data structures for the device.
 */
int xhci_update_hub_device(struct usb_hcd *hcd, struct usb_device *hdev,
                        struct usb_tt *tt, gfp_t mem_flags)
{
        struct xhci_hcd *xhci = hcd_to_xhci(hcd);
        struct xhci_virt_device *vdev;
        struct xhci_command *config_cmd;
        struct xhci_input_control_ctx *ctrl_ctx;
        struct xhci_slot_ctx *slot_ctx;
        unsigned long flags;
        unsigned think_time;
        int ret;

        /* Ignore root hubs */
        if (!hdev->parent)
                return 0;

        vdev = xhci->devs[hdev->slot_id];
        if (!vdev) {
                xhci_warn(xhci, "Cannot update hub desc for unknown device.\n");
                return -EINVAL;
        }
        config_cmd = xhci_alloc_command(xhci, true, true, mem_flags);
        if (!config_cmd) {
                xhci_dbg(xhci, "Could not allocate xHCI command structure.\n");
                return -ENOMEM;
        }

        spin_lock_irqsave(&xhci->lock, flags);
        xhci_slot_copy(xhci, config_cmd->in_ctx, vdev->out_ctx);
        ctrl_ctx = xhci_get_input_control_ctx(xhci, config_cmd->in_ctx);
        ctrl_ctx->add_flags |= cpu_to_le32(SLOT_FLAG);
        slot_ctx = xhci_get_slot_ctx(xhci, config_cmd->in_ctx);
        slot_ctx->dev_info |= cpu_to_le32(DEV_HUB);
        if (tt->multi)
                slot_ctx->dev_info |= cpu_to_le32(DEV_MTT);
        if (xhci->hci_version > 0x95) {
                xhci_dbg(xhci, "xHCI version %x needs hub "
                                "TT think time and number of ports\n",
                                (unsigned int) xhci->hci_version);
                slot_ctx->dev_info2 |= cpu_to_le32(XHCI_MAX_PORTS(hdev->maxchild));
                /* Set TT think time - convert from ns to FS bit times.
                 * 0 = 8 FS bit times, 1 = 16 FS bit times,
                 * 2 = 24 FS bit times, 3 = 32 FS bit times.
                 *
                 * xHCI 1.0: this field shall be 0 if the device is not a
                 * High-spped hub.
                 */
                think_time = tt->think_time;
                if (think_time != 0)
                        think_time = (think_time / 666) - 1;
                if (xhci->hci_version < 0x100 || hdev->speed == USB_SPEED_HIGH)
                        slot_ctx->tt_info |=
                                cpu_to_le32(TT_THINK_TIME(think_time));
        } else {
                xhci_dbg(xhci, "xHCI version %x doesn't need hub "
                                "TT think time or number of ports\n",
                                (unsigned int) xhci->hci_version);
        }
        slot_ctx->dev_state = 0;
        spin_unlock_irqrestore(&xhci->lock, flags);

        xhci_dbg(xhci, "Set up %s for hub device.\n",
                        (xhci->hci_version > 0x95) ?
                        "configure endpoint" : "evaluate context");
        xhci_dbg(xhci, "Slot %u Input Context:\n", hdev->slot_id);
        xhci_dbg_ctx(xhci, config_cmd->in_ctx, 0);

        /* Issue and wait for the configure endpoint or
         * evaluate context command.
         */
        if (xhci->hci_version > 0x95)
                ret = xhci_configure_endpoint(xhci, hdev, config_cmd,
                                false, false);
        else
                ret = xhci_configure_endpoint(xhci, hdev, config_cmd,
                                true, false);

        xhci_dbg(xhci, "Slot %u Output Context:\n", hdev->slot_id);
        xhci_dbg_ctx(xhci, vdev->out_ctx, 0);

        xhci_free_command(xhci, config_cmd);
        return ret;
}

int xhci_get_frame(struct usb_hcd *hcd)
{
        struct xhci_hcd *xhci = hcd_to_xhci(hcd);
        /* EHCI mods by the periodic size.  Why? */
        return xhci_readl(xhci, &xhci->run_regs->microframe_index) >> 3;
}

MODULE_DESCRIPTION(DRIVER_DESC);
MODULE_AUTHOR(DRIVER_AUTHOR);
MODULE_LICENSE("GPL");

static int __init xhci_hcd_init(void)
{
#ifdef CONFIG_PCI
        int retval = 0;

        retval = xhci_register_pci();

        if (retval < 0) {
                printk(KERN_DEBUG "Problem registering PCI driver.");
                return retval;
        }
#endif
        /*
         * Check the compiler generated sizes of structures that must be laid
         * out in specific ways for hardware access.
         */
        BUILD_BUG_ON(sizeof(struct xhci_doorbell_array) != 256*32/8);
        BUILD_BUG_ON(sizeof(struct xhci_slot_ctx) != 8*32/8);
        BUILD_BUG_ON(sizeof(struct xhci_ep_ctx) != 8*32/8);
        /* xhci_device_control has eight fields, and also
         * embeds one xhci_slot_ctx and 31 xhci_ep_ctx
         */
        BUILD_BUG_ON(sizeof(struct xhci_stream_ctx) != 4*32/8);
        BUILD_BUG_ON(sizeof(union xhci_trb) != 4*32/8);
        BUILD_BUG_ON(sizeof(struct xhci_erst_entry) != 4*32/8);
        BUILD_BUG_ON(sizeof(struct xhci_cap_regs) != 7*32/8);
        BUILD_BUG_ON(sizeof(struct xhci_intr_reg) != 8*32/8);
        /* xhci_run_regs has eight fields and embeds 128 xhci_intr_regs */
        BUILD_BUG_ON(sizeof(struct xhci_run_regs) != (8+8*128)*32/8);
        BUILD_BUG_ON(sizeof(struct xhci_doorbell_array) != 256*32/8);
        return 0;
}
module_init(xhci_hcd_init);

static void __exit xhci_hcd_cleanup(void)
{
#ifdef CONFIG_PCI
        xhci_unregister_pci();
#endif
}
module_exit(xhci_hcd_cleanup);