Merge branch 'restriper' of git://github.com/idryomov/btrfs-unstable into integration

[deliverable/linux.git] / drivers / media / video / marvell-ccic / mcam-core.c

/*
 * The Marvell camera core.  This device appears in a number of settings,
 * so it needs platform-specific support outside of the core.
 *
 * Copyright 2011 Jonathan Corbet corbet@lwn.net
 */
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/fs.h>
#include <linux/mm.h>
#include <linux/i2c.h>
#include <linux/interrupt.h>
#include <linux/spinlock.h>
#include <linux/slab.h>
#include <linux/device.h>
#include <linux/wait.h>
#include <linux/list.h>
#include <linux/dma-mapping.h>
#include <linux/delay.h>
#include <linux/vmalloc.h>
#include <linux/io.h>
#include <linux/videodev2.h>
#include <media/v4l2-device.h>
#include <media/v4l2-ioctl.h>
#include <media/v4l2-chip-ident.h>
#include <media/ov7670.h>
#include <media/videobuf2-vmalloc.h>
#include <media/videobuf2-dma-contig.h>
#include <media/videobuf2-dma-sg.h>

#include "mcam-core.h"

/*
 * Basic frame stats - to be deleted shortly
 */
static int frames;
static int singles;
static int delivered;

#ifdef MCAM_MODE_VMALLOC
/*
 * Internal DMA buffer management.  Since the controller cannot do S/G I/O,
 * we must have physically contiguous buffers to bring frames into.
 * These parameters control how many buffers we use, whether we
 * allocate them at load time (better chance of success, but nails down
 * memory) or when somebody tries to use the camera (riskier), and,
 * for load-time allocation, how big they should be.
 *
 * The controller can cycle through three buffers.  We could use
 * more by flipping pointers around, but it probably makes little
 * sense.
 */

static int alloc_bufs_at_read;
module_param(alloc_bufs_at_read, bool, 0444);
MODULE_PARM_DESC(alloc_bufs_at_read,
                "Non-zero value causes DMA buffers to be allocated when the "
                "video capture device is read, rather than at module load "
                "time.  This saves memory, but decreases the chances of "
                "successfully getting those buffers.  This parameter is "
                "only used in the vmalloc buffer mode");

static int n_dma_bufs = 3;
module_param(n_dma_bufs, uint, 0644);
MODULE_PARM_DESC(n_dma_bufs,
                "The number of DMA buffers to allocate.  Can be either two "
                "(saves memory, makes timing tighter) or three.");

static int dma_buf_size = VGA_WIDTH * VGA_HEIGHT * 2;  /* Worst case */
module_param(dma_buf_size, uint, 0444);
MODULE_PARM_DESC(dma_buf_size,
                "The size of the allocated DMA buffers.  If actual operating "
                "parameters require larger buffers, an attempt to reallocate "
                "will be made.");
#else /* MCAM_MODE_VMALLOC */
static const int alloc_bufs_at_read = 0;
static const int n_dma_bufs = 3;  /* Used by S/G_PARM */
#endif /* MCAM_MODE_VMALLOC */

static int flip;
module_param(flip, bool, 0444);
MODULE_PARM_DESC(flip,
                "If set, the sensor will be instructed to flip the image "
                "vertically.");

static int buffer_mode = -1;
module_param(buffer_mode, int, 0444);
MODULE_PARM_DESC(buffer_mode,
                "Set the buffer mode to be used; default is to go with what "
                "the platform driver asks for.  Set to 0 for vmalloc, 1 for "
                "DMA contiguous.");

/*
 * Status flags.  Always manipulated with bit operations.
 */
#define CF_BUF0_VALID    0      /* Buffers valid - first three */
#define CF_BUF1_VALID    1
#define CF_BUF2_VALID    2
#define CF_DMA_ACTIVE    3      /* A frame is incoming */
#define CF_CONFIG_NEEDED 4      /* Must configure hardware */
#define CF_SINGLE_BUFFER 5      /* Running with a single buffer */
#define CF_SG_RESTART    6      /* SG restart needed */

#define sensor_call(cam, o, f, args...) \
        v4l2_subdev_call(cam->sensor, o, f, ##args)

static struct mcam_format_struct {
        __u8 *desc;
        __u32 pixelformat;
        int bpp;   /* Bytes per pixel */
        enum v4l2_mbus_pixelcode mbus_code;
} mcam_formats[] = {
        {
                .desc           = "YUYV 4:2:2",
                .pixelformat    = V4L2_PIX_FMT_YUYV,
                .mbus_code      = V4L2_MBUS_FMT_YUYV8_2X8,
                .bpp            = 2,
        },
        {
                .desc           = "RGB 444",
                .pixelformat    = V4L2_PIX_FMT_RGB444,
                .mbus_code      = V4L2_MBUS_FMT_RGB444_2X8_PADHI_LE,
                .bpp            = 2,
        },
        {
                .desc           = "RGB 565",
                .pixelformat    = V4L2_PIX_FMT_RGB565,
                .mbus_code      = V4L2_MBUS_FMT_RGB565_2X8_LE,
                .bpp            = 2,
        },
        {
                .desc           = "Raw RGB Bayer",
                .pixelformat    = V4L2_PIX_FMT_SBGGR8,
                .mbus_code      = V4L2_MBUS_FMT_SBGGR8_1X8,
                .bpp            = 1
        },
};
#define N_MCAM_FMTS ARRAY_SIZE(mcam_formats)

static struct mcam_format_struct *mcam_find_format(u32 pixelformat)
{
        unsigned i;

        for (i = 0; i < N_MCAM_FMTS; i++)
                if (mcam_formats[i].pixelformat == pixelformat)
                        return mcam_formats + i;
        /* Not found? Then return the first format. */
        return mcam_formats;
}

/*
 * The default format we use until somebody says otherwise.
 */
static const struct v4l2_pix_format mcam_def_pix_format = {
        .width          = VGA_WIDTH,
        .height         = VGA_HEIGHT,
        .pixelformat    = V4L2_PIX_FMT_YUYV,
        .field          = V4L2_FIELD_NONE,
        .bytesperline   = VGA_WIDTH*2,
        .sizeimage      = VGA_WIDTH*VGA_HEIGHT*2,
};

static const enum v4l2_mbus_pixelcode mcam_def_mbus_code =
                                        V4L2_MBUS_FMT_YUYV8_2X8;


/*
 * The two-word DMA descriptor format used by the Armada 610 and like.  There
 * Is a three-word format as well (set C1_DESC_3WORD) where the third
 * word is a pointer to the next descriptor, but we don't use it.  Two-word
 * descriptors have to be contiguous in memory.
 */
struct mcam_dma_desc {
        u32 dma_addr;
        u32 segment_len;
};

/*
 * Our buffer type for working with videobuf2.  Note that the vb2
 * developers have decreed that struct vb2_buffer must be at the
 * beginning of this structure.
 */
struct mcam_vb_buffer {
        struct vb2_buffer vb_buf;
        struct list_head queue;
        struct mcam_dma_desc *dma_desc; /* Descriptor virtual address */
        dma_addr_t dma_desc_pa;         /* Descriptor physical address */
        int dma_desc_nent;              /* Number of mapped descriptors */
};

static inline struct mcam_vb_buffer *vb_to_mvb(struct vb2_buffer *vb)
{
        return container_of(vb, struct mcam_vb_buffer, vb_buf);
}

/*
 * Hand a completed buffer back to user space.
 */
static void mcam_buffer_done(struct mcam_camera *cam, int frame,
                struct vb2_buffer *vbuf)
{
        vbuf->v4l2_buf.bytesused = cam->pix_format.sizeimage;
        vbuf->v4l2_buf.sequence = cam->buf_seq[frame];
        vb2_set_plane_payload(vbuf, 0, cam->pix_format.sizeimage);
        vb2_buffer_done(vbuf, VB2_BUF_STATE_DONE);
}



/*
 * Debugging and related.
 */
#define cam_err(cam, fmt, arg...) \
        dev_err((cam)->dev, fmt, ##arg);
#define cam_warn(cam, fmt, arg...) \
        dev_warn((cam)->dev, fmt, ##arg);
#define cam_dbg(cam, fmt, arg...) \
        dev_dbg((cam)->dev, fmt, ##arg);


/*
 * Flag manipulation helpers
 */
static void mcam_reset_buffers(struct mcam_camera *cam)
{
        int i;

        cam->next_buf = -1;
        for (i = 0; i < cam->nbufs; i++)
                clear_bit(i, &cam->flags);
}

static inline int mcam_needs_config(struct mcam_camera *cam)
{
        return test_bit(CF_CONFIG_NEEDED, &cam->flags);
}

static void mcam_set_config_needed(struct mcam_camera *cam, int needed)
{
        if (needed)
                set_bit(CF_CONFIG_NEEDED, &cam->flags);
        else
                clear_bit(CF_CONFIG_NEEDED, &cam->flags);
}

/* ------------------------------------------------------------------- */
/*
 * Make the controller start grabbing images.  Everything must
 * be set up before doing this.
 */
static void mcam_ctlr_start(struct mcam_camera *cam)
{
        /* set_bit performs a read, so no other barrier should be
           needed here */
        mcam_reg_set_bit(cam, REG_CTRL0, C0_ENABLE);
}

static void mcam_ctlr_stop(struct mcam_camera *cam)
{
        mcam_reg_clear_bit(cam, REG_CTRL0, C0_ENABLE);
}

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

#ifdef MCAM_MODE_VMALLOC
/*
 * Code specific to the vmalloc buffer mode.
 */

/*
 * Allocate in-kernel DMA buffers for vmalloc mode.
 */
static int mcam_alloc_dma_bufs(struct mcam_camera *cam, int loadtime)
{
        int i;

        mcam_set_config_needed(cam, 1);
        if (loadtime)
                cam->dma_buf_size = dma_buf_size;
        else
                cam->dma_buf_size = cam->pix_format.sizeimage;
        if (n_dma_bufs > 3)
                n_dma_bufs = 3;

        cam->nbufs = 0;
        for (i = 0; i < n_dma_bufs; i++) {
                cam->dma_bufs[i] = dma_alloc_coherent(cam->dev,
                                cam->dma_buf_size, cam->dma_handles + i,
                                GFP_KERNEL);
                if (cam->dma_bufs[i] == NULL) {
                        cam_warn(cam, "Failed to allocate DMA buffer\n");
                        break;
                }
                (cam->nbufs)++;
        }

        switch (cam->nbufs) {
        case 1:
                dma_free_coherent(cam->dev, cam->dma_buf_size,
                                cam->dma_bufs[0], cam->dma_handles[0]);
                cam->nbufs = 0;
        case 0:
                cam_err(cam, "Insufficient DMA buffers, cannot operate\n");
                return -ENOMEM;

        case 2:
                if (n_dma_bufs > 2)
                        cam_warn(cam, "Will limp along with only 2 buffers\n");
                break;
        }
        return 0;
}

static void mcam_free_dma_bufs(struct mcam_camera *cam)
{
        int i;

        for (i = 0; i < cam->nbufs; i++) {
                dma_free_coherent(cam->dev, cam->dma_buf_size,
                                cam->dma_bufs[i], cam->dma_handles[i]);
                cam->dma_bufs[i] = NULL;
        }
        cam->nbufs = 0;
}


/*
 * Set up DMA buffers when operating in vmalloc mode
 */
static void mcam_ctlr_dma_vmalloc(struct mcam_camera *cam)
{
        /*
         * Store the first two Y buffers (we aren't supporting
         * planar formats for now, so no UV bufs).  Then either
         * set the third if it exists, or tell the controller
         * to just use two.
         */
        mcam_reg_write(cam, REG_Y0BAR, cam->dma_handles[0]);
        mcam_reg_write(cam, REG_Y1BAR, cam->dma_handles[1]);
        if (cam->nbufs > 2) {
                mcam_reg_write(cam, REG_Y2BAR, cam->dma_handles[2]);
                mcam_reg_clear_bit(cam, REG_CTRL1, C1_TWOBUFS);
        } else
                mcam_reg_set_bit(cam, REG_CTRL1, C1_TWOBUFS);
        if (cam->chip_id == V4L2_IDENT_CAFE)
                mcam_reg_write(cam, REG_UBAR, 0); /* 32 bits only */
}

/*
 * Copy data out to user space in the vmalloc case
 */
static void mcam_frame_tasklet(unsigned long data)
{
        struct mcam_camera *cam = (struct mcam_camera *) data;
        int i;
        unsigned long flags;
        struct mcam_vb_buffer *buf;

        spin_lock_irqsave(&cam->dev_lock, flags);
        for (i = 0; i < cam->nbufs; i++) {
                int bufno = cam->next_buf;

                if (cam->state != S_STREAMING || bufno < 0)
                        break;  /* I/O got stopped */
                if (++(cam->next_buf) >= cam->nbufs)
                        cam->next_buf = 0;
                if (!test_bit(bufno, &cam->flags))
                        continue;
                if (list_empty(&cam->buffers)) {
                        singles++;
                        break;  /* Leave it valid, hope for better later */
                }
                delivered++;
                clear_bit(bufno, &cam->flags);
                buf = list_first_entry(&cam->buffers, struct mcam_vb_buffer,
                                queue);
                list_del_init(&buf->queue);
                /*
                 * Drop the lock during the big copy.  This *should* be safe...
                 */
                spin_unlock_irqrestore(&cam->dev_lock, flags);
                memcpy(vb2_plane_vaddr(&buf->vb_buf, 0), cam->dma_bufs[bufno],
                                cam->pix_format.sizeimage);
                mcam_buffer_done(cam, bufno, &buf->vb_buf);
                spin_lock_irqsave(&cam->dev_lock, flags);
        }
        spin_unlock_irqrestore(&cam->dev_lock, flags);
}


/*
 * Make sure our allocated buffers are up to the task.
 */
static int mcam_check_dma_buffers(struct mcam_camera *cam)
{
        if (cam->nbufs > 0 && cam->dma_buf_size < cam->pix_format.sizeimage)
                        mcam_free_dma_bufs(cam);
        if (cam->nbufs == 0)
                return mcam_alloc_dma_bufs(cam, 0);
        return 0;
}

static void mcam_vmalloc_done(struct mcam_camera *cam, int frame)
{
        tasklet_schedule(&cam->s_tasklet);
}

#else /* MCAM_MODE_VMALLOC */

static inline int mcam_alloc_dma_bufs(struct mcam_camera *cam, int loadtime)
{
        return 0;
}

static inline void mcam_free_dma_bufs(struct mcam_camera *cam)
{
        return;
}

static inline int mcam_check_dma_buffers(struct mcam_camera *cam)
{
        return 0;
}



#endif /* MCAM_MODE_VMALLOC */


#ifdef MCAM_MODE_DMA_CONTIG
/* ---------------------------------------------------------------------- */
/*
 * DMA-contiguous code.
 */
/*
 * Set up a contiguous buffer for the given frame.  Here also is where
 * the underrun strategy is set: if there is no buffer available, reuse
 * the buffer from the other BAR and set the CF_SINGLE_BUFFER flag to
 * keep the interrupt handler from giving that buffer back to user
 * space.  In this way, we always have a buffer to DMA to and don't
 * have to try to play games stopping and restarting the controller.
 */
static void mcam_set_contig_buffer(struct mcam_camera *cam, int frame)
{
        struct mcam_vb_buffer *buf;
        /*
         * If there are no available buffers, go into single mode
         */
        if (list_empty(&cam->buffers)) {
                buf = cam->vb_bufs[frame ^ 0x1];
                cam->vb_bufs[frame] = buf;
                mcam_reg_write(cam, frame == 0 ? REG_Y0BAR : REG_Y1BAR,
                                vb2_dma_contig_plane_dma_addr(&buf->vb_buf, 0));
                set_bit(CF_SINGLE_BUFFER, &cam->flags);
                singles++;
                return;
        }
        /*
         * OK, we have a buffer we can use.
         */
        buf = list_first_entry(&cam->buffers, struct mcam_vb_buffer, queue);
        list_del_init(&buf->queue);
        mcam_reg_write(cam, frame == 0 ? REG_Y0BAR : REG_Y1BAR,
                        vb2_dma_contig_plane_dma_addr(&buf->vb_buf, 0));
        cam->vb_bufs[frame] = buf;
        clear_bit(CF_SINGLE_BUFFER, &cam->flags);
}

/*
 * Initial B_DMA_contig setup.
 */
static void mcam_ctlr_dma_contig(struct mcam_camera *cam)
{
        mcam_reg_set_bit(cam, REG_CTRL1, C1_TWOBUFS);
        cam->nbufs = 2;
        mcam_set_contig_buffer(cam, 0);
        mcam_set_contig_buffer(cam, 1);
}

/*
 * Frame completion handling.
 */
static void mcam_dma_contig_done(struct mcam_camera *cam, int frame)
{
        struct mcam_vb_buffer *buf = cam->vb_bufs[frame];

        if (!test_bit(CF_SINGLE_BUFFER, &cam->flags)) {
                delivered++;
                mcam_buffer_done(cam, frame, &buf->vb_buf);
        }
        mcam_set_contig_buffer(cam, frame);
}

#endif /* MCAM_MODE_DMA_CONTIG */

#ifdef MCAM_MODE_DMA_SG
/* ---------------------------------------------------------------------- */
/*
 * Scatter/gather-specific code.
 */

/*
 * Set up the next buffer for S/G I/O; caller should be sure that
 * the controller is stopped and a buffer is available.
 */
static void mcam_sg_next_buffer(struct mcam_camera *cam)
{
        struct mcam_vb_buffer *buf;

        buf = list_first_entry(&cam->buffers, struct mcam_vb_buffer, queue);
        list_del_init(&buf->queue);
        mcam_reg_write(cam, REG_DMA_DESC_Y, buf->dma_desc_pa);
        mcam_reg_write(cam, REG_DESC_LEN_Y,
                        buf->dma_desc_nent*sizeof(struct mcam_dma_desc));
        mcam_reg_write(cam, REG_DESC_LEN_U, 0);
        mcam_reg_write(cam, REG_DESC_LEN_V, 0);
        cam->vb_bufs[0] = buf;
}

/*
 * Initial B_DMA_sg setup
 */
static void mcam_ctlr_dma_sg(struct mcam_camera *cam)
{
        mcam_reg_clear_bit(cam, REG_CTRL1, C1_DESC_3WORD);
        mcam_sg_next_buffer(cam);
        mcam_reg_set_bit(cam, REG_CTRL1, C1_DESC_ENA);
        cam->nbufs = 3;
}


/*
 * Frame completion with S/G is trickier.  We can't muck with
 * a descriptor chain on the fly, since the controller buffers it
 * internally.  So we have to actually stop and restart; Marvell
 * says this is the way to do it.
 *
 * Of course, stopping is easier said than done; experience shows
 * that the controller can start a frame *after* C0_ENABLE has been
 * cleared.  So when running in S/G mode, the controller is "stopped"
 * on receipt of the start-of-frame interrupt.  That means we can
 * safely change the DMA descriptor array here and restart things
 * (assuming there's another buffer waiting to go).
 */
static void mcam_dma_sg_done(struct mcam_camera *cam, int frame)
{
        struct mcam_vb_buffer *buf = cam->vb_bufs[0];

        /*
         * Very Bad Not Good Things happen if you don't clear
         * C1_DESC_ENA before making any descriptor changes.
         */
        mcam_reg_clear_bit(cam, REG_CTRL1, C1_DESC_ENA);
        /*
         * If we have another buffer available, put it in and
         * restart the engine.
         */
        if (!list_empty(&cam->buffers)) {
                mcam_sg_next_buffer(cam);
                mcam_reg_set_bit(cam, REG_CTRL1, C1_DESC_ENA);
                mcam_ctlr_start(cam);
        /*
         * Otherwise set CF_SG_RESTART and the controller will
         * be restarted once another buffer shows up.
         */
        } else {
                set_bit(CF_SG_RESTART, &cam->flags);
                singles++;
        }
        /*
         * Now we can give the completed frame back to user space.
         */
        delivered++;
        mcam_buffer_done(cam, frame, &buf->vb_buf);
}


/*
 * Scatter/gather mode requires stopping the controller between
 * frames so we can put in a new DMA descriptor array.  If no new
 * buffer exists at frame completion, the controller is left stopped;
 * this function is charged with gettig things going again.
 */
static void mcam_sg_restart(struct mcam_camera *cam)
{
        mcam_ctlr_dma_sg(cam);
        mcam_ctlr_start(cam);
        clear_bit(CF_SG_RESTART, &cam->flags);
}

#else /* MCAM_MODE_DMA_SG */

static inline void mcam_sg_restart(struct mcam_camera *cam)
{
        return;
}

#endif /* MCAM_MODE_DMA_SG */

/* ---------------------------------------------------------------------- */
/*
 * Buffer-mode-independent controller code.
 */

/*
 * Image format setup
 */
static void mcam_ctlr_image(struct mcam_camera *cam)
{
        int imgsz;
        struct v4l2_pix_format *fmt = &cam->pix_format;

        imgsz = ((fmt->height << IMGSZ_V_SHIFT) & IMGSZ_V_MASK) |
                (fmt->bytesperline & IMGSZ_H_MASK);
        mcam_reg_write(cam, REG_IMGSIZE, imgsz);
        mcam_reg_write(cam, REG_IMGOFFSET, 0);
        /* YPITCH just drops the last two bits */
        mcam_reg_write_mask(cam, REG_IMGPITCH, fmt->bytesperline,
                        IMGP_YP_MASK);
        /*
         * Tell the controller about the image format we are using.
         */
        switch (cam->pix_format.pixelformat) {
        case V4L2_PIX_FMT_YUYV:
            mcam_reg_write_mask(cam, REG_CTRL0,
                            C0_DF_YUV|C0_YUV_PACKED|C0_YUVE_YUYV,
                            C0_DF_MASK);
            break;

        case V4L2_PIX_FMT_RGB444:
            mcam_reg_write_mask(cam, REG_CTRL0,
                            C0_DF_RGB|C0_RGBF_444|C0_RGB4_XRGB,
                            C0_DF_MASK);
                /* Alpha value? */
            break;

        case V4L2_PIX_FMT_RGB565:
            mcam_reg_write_mask(cam, REG_CTRL0,
                            C0_DF_RGB|C0_RGBF_565|C0_RGB5_BGGR,
                            C0_DF_MASK);
            break;

        default:
            cam_err(cam, "Unknown format %x\n", cam->pix_format.pixelformat);
            break;
        }
        /*
         * Make sure it knows we want to use hsync/vsync.
         */
        mcam_reg_write_mask(cam, REG_CTRL0, C0_SIF_HVSYNC,
                        C0_SIFM_MASK);
}


/*
 * Configure the controller for operation; caller holds the
 * device mutex.
 */
static int mcam_ctlr_configure(struct mcam_camera *cam)
{
        unsigned long flags;

        spin_lock_irqsave(&cam->dev_lock, flags);
        cam->dma_setup(cam);
        mcam_ctlr_image(cam);
        mcam_set_config_needed(cam, 0);
        clear_bit(CF_SG_RESTART, &cam->flags);
        spin_unlock_irqrestore(&cam->dev_lock, flags);
        return 0;
}

static void mcam_ctlr_irq_enable(struct mcam_camera *cam)
{
        /*
         * Clear any pending interrupts, since we do not
         * expect to have I/O active prior to enabling.
         */
        mcam_reg_write(cam, REG_IRQSTAT, FRAMEIRQS);
        mcam_reg_set_bit(cam, REG_IRQMASK, FRAMEIRQS);
}

static void mcam_ctlr_irq_disable(struct mcam_camera *cam)
{
        mcam_reg_clear_bit(cam, REG_IRQMASK, FRAMEIRQS);
}



static void mcam_ctlr_init(struct mcam_camera *cam)
{
        unsigned long flags;

        spin_lock_irqsave(&cam->dev_lock, flags);
        /*
         * Make sure it's not powered down.
         */
        mcam_reg_clear_bit(cam, REG_CTRL1, C1_PWRDWN);
        /*
         * Turn off the enable bit.  It sure should be off anyway,
         * but it's good to be sure.
         */
        mcam_reg_clear_bit(cam, REG_CTRL0, C0_ENABLE);
        /*
         * Clock the sensor appropriately.  Controller clock should
         * be 48MHz, sensor "typical" value is half that.
         */
        mcam_reg_write_mask(cam, REG_CLKCTRL, 2, CLK_DIV_MASK);
        spin_unlock_irqrestore(&cam->dev_lock, flags);
}


/*
 * Stop the controller, and don't return until we're really sure that no
 * further DMA is going on.
 */
static void mcam_ctlr_stop_dma(struct mcam_camera *cam)
{
        unsigned long flags;

        /*
         * Theory: stop the camera controller (whether it is operating
         * or not).  Delay briefly just in case we race with the SOF
         * interrupt, then wait until no DMA is active.
         */
        spin_lock_irqsave(&cam->dev_lock, flags);
        clear_bit(CF_SG_RESTART, &cam->flags);
        mcam_ctlr_stop(cam);
        cam->state = S_IDLE;
        spin_unlock_irqrestore(&cam->dev_lock, flags);
        msleep(40);
        if (test_bit(CF_DMA_ACTIVE, &cam->flags))
                cam_err(cam, "Timeout waiting for DMA to end\n");
                /* This would be bad news - what now? */
        spin_lock_irqsave(&cam->dev_lock, flags);
        mcam_ctlr_irq_disable(cam);
        spin_unlock_irqrestore(&cam->dev_lock, flags);
}

/*
 * Power up and down.
 */
static void mcam_ctlr_power_up(struct mcam_camera *cam)
{
        unsigned long flags;

        spin_lock_irqsave(&cam->dev_lock, flags);
        cam->plat_power_up(cam);
        mcam_reg_clear_bit(cam, REG_CTRL1, C1_PWRDWN);
        spin_unlock_irqrestore(&cam->dev_lock, flags);
        msleep(5); /* Just to be sure */
}

static void mcam_ctlr_power_down(struct mcam_camera *cam)
{
        unsigned long flags;

        spin_lock_irqsave(&cam->dev_lock, flags);
        /*
         * School of hard knocks department: be sure we do any register
         * twiddling on the controller *before* calling the platform
         * power down routine.
         */
        mcam_reg_set_bit(cam, REG_CTRL1, C1_PWRDWN);
        cam->plat_power_down(cam);
        spin_unlock_irqrestore(&cam->dev_lock, flags);
}

/* -------------------------------------------------------------------- */
/*
 * Communications with the sensor.
 */

static int __mcam_cam_reset(struct mcam_camera *cam)
{
        return sensor_call(cam, core, reset, 0);
}

/*
 * We have found the sensor on the i2c.  Let's try to have a
 * conversation.
 */
static int mcam_cam_init(struct mcam_camera *cam)
{
        struct v4l2_dbg_chip_ident chip;
        int ret;

        mutex_lock(&cam->s_mutex);
        if (cam->state != S_NOTREADY)
                cam_warn(cam, "Cam init with device in funky state %d",
                                cam->state);
        ret = __mcam_cam_reset(cam);
        if (ret)
                goto out;
        chip.ident = V4L2_IDENT_NONE;
        chip.match.type = V4L2_CHIP_MATCH_I2C_ADDR;
        chip.match.addr = cam->sensor_addr;
        ret = sensor_call(cam, core, g_chip_ident, &chip);
        if (ret)
                goto out;
        cam->sensor_type = chip.ident;
        if (cam->sensor_type != V4L2_IDENT_OV7670) {
                cam_err(cam, "Unsupported sensor type 0x%x", cam->sensor_type);
                ret = -EINVAL;
                goto out;
        }
/* Get/set parameters? */
        ret = 0;
        cam->state = S_IDLE;
out:
        mcam_ctlr_power_down(cam);
        mutex_unlock(&cam->s_mutex);
        return ret;
}

/*
 * Configure the sensor to match the parameters we have.  Caller should
 * hold s_mutex
 */
static int mcam_cam_set_flip(struct mcam_camera *cam)
{
        struct v4l2_control ctrl;

        memset(&ctrl, 0, sizeof(ctrl));
        ctrl.id = V4L2_CID_VFLIP;
        ctrl.value = flip;
        return sensor_call(cam, core, s_ctrl, &ctrl);
}


static int mcam_cam_configure(struct mcam_camera *cam)
{
        struct v4l2_mbus_framefmt mbus_fmt;
        int ret;

        v4l2_fill_mbus_format(&mbus_fmt, &cam->pix_format, cam->mbus_code);
        ret = sensor_call(cam, core, init, 0);
        if (ret == 0)
                ret = sensor_call(cam, video, s_mbus_fmt, &mbus_fmt);
        /*
         * OV7670 does weird things if flip is set *before* format...
         */
        ret += mcam_cam_set_flip(cam);
        return ret;
}

/*
 * Get everything ready, and start grabbing frames.
 */
static int mcam_read_setup(struct mcam_camera *cam)
{
        int ret;
        unsigned long flags;

        /*
         * Configuration.  If we still don't have DMA buffers,
         * make one last, desperate attempt.
         */
        if (cam->buffer_mode == B_vmalloc && cam->nbufs == 0 &&
                        mcam_alloc_dma_bufs(cam, 0))
                return -ENOMEM;

        if (mcam_needs_config(cam)) {
                mcam_cam_configure(cam);
                ret = mcam_ctlr_configure(cam);
                if (ret)
                        return ret;
        }

        /*
         * Turn it loose.
         */
        spin_lock_irqsave(&cam->dev_lock, flags);
        mcam_reset_buffers(cam);
        mcam_ctlr_irq_enable(cam);
        cam->state = S_STREAMING;
        mcam_ctlr_start(cam);
        spin_unlock_irqrestore(&cam->dev_lock, flags);
        return 0;
}

/* ----------------------------------------------------------------------- */
/*
 * Videobuf2 interface code.
 */

static int mcam_vb_queue_setup(struct vb2_queue *vq,
                const struct v4l2_format *fmt, unsigned int *nbufs,
                unsigned int *num_planes, unsigned int sizes[],
                void *alloc_ctxs[])
{
        struct mcam_camera *cam = vb2_get_drv_priv(vq);
        int minbufs = (cam->buffer_mode == B_DMA_contig) ? 3 : 2;

        sizes[0] = cam->pix_format.sizeimage;
        *num_planes = 1; /* Someday we have to support planar formats... */
        if (*nbufs < minbufs)
                *nbufs = minbufs;
        if (cam->buffer_mode == B_DMA_contig)
                alloc_ctxs[0] = cam->vb_alloc_ctx;
        return 0;
}


static void mcam_vb_buf_queue(struct vb2_buffer *vb)
{
        struct mcam_vb_buffer *mvb = vb_to_mvb(vb);
        struct mcam_camera *cam = vb2_get_drv_priv(vb->vb2_queue);
        unsigned long flags;
        int start;

        spin_lock_irqsave(&cam->dev_lock, flags);
        start = (cam->state == S_BUFWAIT) && !list_empty(&cam->buffers);
        list_add(&mvb->queue, &cam->buffers);
        if (test_bit(CF_SG_RESTART, &cam->flags))
                mcam_sg_restart(cam);
        spin_unlock_irqrestore(&cam->dev_lock, flags);
        if (start)
                mcam_read_setup(cam);
}


/*
 * vb2 uses these to release the mutex when waiting in dqbuf.  I'm
 * not actually sure we need to do this (I'm not sure that vb2_dqbuf() needs
 * to be called with the mutex held), but better safe than sorry.
 */
static void mcam_vb_wait_prepare(struct vb2_queue *vq)
{
        struct mcam_camera *cam = vb2_get_drv_priv(vq);

        mutex_unlock(&cam->s_mutex);
}

static void mcam_vb_wait_finish(struct vb2_queue *vq)
{
        struct mcam_camera *cam = vb2_get_drv_priv(vq);

        mutex_lock(&cam->s_mutex);
}

/*
 * These need to be called with the mutex held from vb2
 */
static int mcam_vb_start_streaming(struct vb2_queue *vq, unsigned int count)
{
        struct mcam_camera *cam = vb2_get_drv_priv(vq);

        if (cam->state != S_IDLE) {
                INIT_LIST_HEAD(&cam->buffers);
                return -EINVAL;
        }
        cam->sequence = 0;
        /*
         * Videobuf2 sneakily hoards all the buffers and won't
         * give them to us until *after* streaming starts.  But
         * we can't actually start streaming until we have a
         * destination.  So go into a wait state and hope they
         * give us buffers soon.
         */
        if (cam->buffer_mode != B_vmalloc && list_empty(&cam->buffers)) {
                cam->state = S_BUFWAIT;
                return 0;
        }
        return mcam_read_setup(cam);
}

static int mcam_vb_stop_streaming(struct vb2_queue *vq)
{
        struct mcam_camera *cam = vb2_get_drv_priv(vq);
        unsigned long flags;

        if (cam->state == S_BUFWAIT) {
                /* They never gave us buffers */
                cam->state = S_IDLE;
                return 0;
        }
        if (cam->state != S_STREAMING)
                return -EINVAL;
        mcam_ctlr_stop_dma(cam);
        /*
         * VB2 reclaims the buffers, so we need to forget
         * about them.
         */
        spin_lock_irqsave(&cam->dev_lock, flags);
        INIT_LIST_HEAD(&cam->buffers);
        spin_unlock_irqrestore(&cam->dev_lock, flags);
        return 0;
}


static const struct vb2_ops mcam_vb2_ops = {
        .queue_setup            = mcam_vb_queue_setup,
        .buf_queue              = mcam_vb_buf_queue,
        .start_streaming        = mcam_vb_start_streaming,
        .stop_streaming         = mcam_vb_stop_streaming,
        .wait_prepare           = mcam_vb_wait_prepare,
        .wait_finish            = mcam_vb_wait_finish,
};


#ifdef MCAM_MODE_DMA_SG
/*
 * Scatter/gather mode uses all of the above functions plus a
 * few extras to deal with DMA mapping.
 */
static int mcam_vb_sg_buf_init(struct vb2_buffer *vb)
{
        struct mcam_vb_buffer *mvb = vb_to_mvb(vb);
        struct mcam_camera *cam = vb2_get_drv_priv(vb->vb2_queue);
        int ndesc = cam->pix_format.sizeimage/PAGE_SIZE + 1;

        mvb->dma_desc = dma_alloc_coherent(cam->dev,
                        ndesc * sizeof(struct mcam_dma_desc),
                        &mvb->dma_desc_pa, GFP_KERNEL);
        if (mvb->dma_desc == NULL) {
                cam_err(cam, "Unable to get DMA descriptor array\n");
                return -ENOMEM;
        }
        return 0;
}

static int mcam_vb_sg_buf_prepare(struct vb2_buffer *vb)
{
        struct mcam_vb_buffer *mvb = vb_to_mvb(vb);
        struct mcam_camera *cam = vb2_get_drv_priv(vb->vb2_queue);
        struct vb2_dma_sg_desc *sgd = vb2_dma_sg_plane_desc(vb, 0);
        struct mcam_dma_desc *desc = mvb->dma_desc;
        struct scatterlist *sg;
        int i;

        mvb->dma_desc_nent = dma_map_sg(cam->dev, sgd->sglist, sgd->num_pages,
                        DMA_FROM_DEVICE);
        if (mvb->dma_desc_nent <= 0)
                return -EIO;  /* Not sure what's right here */
        for_each_sg(sgd->sglist, sg, mvb->dma_desc_nent, i) {
                desc->dma_addr = sg_dma_address(sg);
                desc->segment_len = sg_dma_len(sg);
                desc++;
        }
        return 0;
}

static int mcam_vb_sg_buf_finish(struct vb2_buffer *vb)
{
        struct mcam_camera *cam = vb2_get_drv_priv(vb->vb2_queue);
        struct vb2_dma_sg_desc *sgd = vb2_dma_sg_plane_desc(vb, 0);

        dma_unmap_sg(cam->dev, sgd->sglist, sgd->num_pages, DMA_FROM_DEVICE);
        return 0;
}

static void mcam_vb_sg_buf_cleanup(struct vb2_buffer *vb)
{
        struct mcam_camera *cam = vb2_get_drv_priv(vb->vb2_queue);
        struct mcam_vb_buffer *mvb = vb_to_mvb(vb);
        int ndesc = cam->pix_format.sizeimage/PAGE_SIZE + 1;

        dma_free_coherent(cam->dev, ndesc * sizeof(struct mcam_dma_desc),
                        mvb->dma_desc, mvb->dma_desc_pa);
}


static const struct vb2_ops mcam_vb2_sg_ops = {
        .queue_setup            = mcam_vb_queue_setup,
        .buf_init               = mcam_vb_sg_buf_init,
        .buf_prepare            = mcam_vb_sg_buf_prepare,
        .buf_queue              = mcam_vb_buf_queue,
        .buf_finish             = mcam_vb_sg_buf_finish,
        .buf_cleanup            = mcam_vb_sg_buf_cleanup,
        .start_streaming        = mcam_vb_start_streaming,
        .stop_streaming         = mcam_vb_stop_streaming,
        .wait_prepare           = mcam_vb_wait_prepare,
        .wait_finish            = mcam_vb_wait_finish,
};

#endif /* MCAM_MODE_DMA_SG */

static int mcam_setup_vb2(struct mcam_camera *cam)
{
        struct vb2_queue *vq = &cam->vb_queue;

        memset(vq, 0, sizeof(*vq));
        vq->type = V4L2_BUF_TYPE_VIDEO_CAPTURE;
        vq->drv_priv = cam;
        INIT_LIST_HEAD(&cam->buffers);
        switch (cam->buffer_mode) {
        case B_DMA_contig:
#ifdef MCAM_MODE_DMA_CONTIG
                vq->ops = &mcam_vb2_ops;
                vq->mem_ops = &vb2_dma_contig_memops;
                cam->vb_alloc_ctx = vb2_dma_contig_init_ctx(cam->dev);
                vq->io_modes = VB2_MMAP | VB2_USERPTR;
                cam->dma_setup = mcam_ctlr_dma_contig;
                cam->frame_complete = mcam_dma_contig_done;
#endif
                break;
        case B_DMA_sg:
#ifdef MCAM_MODE_DMA_SG
                vq->ops = &mcam_vb2_sg_ops;
                vq->mem_ops = &vb2_dma_sg_memops;
                vq->io_modes = VB2_MMAP | VB2_USERPTR;
                cam->dma_setup = mcam_ctlr_dma_sg;
                cam->frame_complete = mcam_dma_sg_done;
#endif
                break;
        case B_vmalloc:
#ifdef MCAM_MODE_VMALLOC
                tasklet_init(&cam->s_tasklet, mcam_frame_tasklet,
                                (unsigned long) cam);
                vq->ops = &mcam_vb2_ops;
                vq->mem_ops = &vb2_vmalloc_memops;
                vq->buf_struct_size = sizeof(struct mcam_vb_buffer);
                vq->io_modes = VB2_MMAP;
                cam->dma_setup = mcam_ctlr_dma_vmalloc;
                cam->frame_complete = mcam_vmalloc_done;
#endif
                break;
        }
        return vb2_queue_init(vq);
}

static void mcam_cleanup_vb2(struct mcam_camera *cam)
{
        vb2_queue_release(&cam->vb_queue);
#ifdef MCAM_MODE_DMA_CONTIG
        if (cam->buffer_mode == B_DMA_contig)
                vb2_dma_contig_cleanup_ctx(cam->vb_alloc_ctx);
#endif
}


/* ---------------------------------------------------------------------- */
/*
 * The long list of V4L2 ioctl() operations.
 */

static int mcam_vidioc_streamon(struct file *filp, void *priv,
                enum v4l2_buf_type type)
{
        struct mcam_camera *cam = filp->private_data;
        int ret;

        mutex_lock(&cam->s_mutex);
        ret = vb2_streamon(&cam->vb_queue, type);
        mutex_unlock(&cam->s_mutex);
        return ret;
}


static int mcam_vidioc_streamoff(struct file *filp, void *priv,
                enum v4l2_buf_type type)
{
        struct mcam_camera *cam = filp->private_data;
        int ret;

        mutex_lock(&cam->s_mutex);
        ret = vb2_streamoff(&cam->vb_queue, type);
        mutex_unlock(&cam->s_mutex);
        return ret;
}


static int mcam_vidioc_reqbufs(struct file *filp, void *priv,
                struct v4l2_requestbuffers *req)
{
        struct mcam_camera *cam = filp->private_data;
        int ret;

        mutex_lock(&cam->s_mutex);
        ret = vb2_reqbufs(&cam->vb_queue, req);
        mutex_unlock(&cam->s_mutex);
        return ret;
}


static int mcam_vidioc_querybuf(struct file *filp, void *priv,
                struct v4l2_buffer *buf)
{
        struct mcam_camera *cam = filp->private_data;
        int ret;

        mutex_lock(&cam->s_mutex);
        ret = vb2_querybuf(&cam->vb_queue, buf);
        mutex_unlock(&cam->s_mutex);
        return ret;
}

static int mcam_vidioc_qbuf(struct file *filp, void *priv,
                struct v4l2_buffer *buf)
{
        struct mcam_camera *cam = filp->private_data;
        int ret;

        mutex_lock(&cam->s_mutex);
        ret = vb2_qbuf(&cam->vb_queue, buf);
        mutex_unlock(&cam->s_mutex);
        return ret;
}

static int mcam_vidioc_dqbuf(struct file *filp, void *priv,
                struct v4l2_buffer *buf)
{
        struct mcam_camera *cam = filp->private_data;
        int ret;

        mutex_lock(&cam->s_mutex);
        ret = vb2_dqbuf(&cam->vb_queue, buf, filp->f_flags & O_NONBLOCK);
        mutex_unlock(&cam->s_mutex);
        return ret;
}



static int mcam_vidioc_queryctrl(struct file *filp, void *priv,
                struct v4l2_queryctrl *qc)
{
        struct mcam_camera *cam = priv;
        int ret;

        mutex_lock(&cam->s_mutex);
        ret = sensor_call(cam, core, queryctrl, qc);
        mutex_unlock(&cam->s_mutex);
        return ret;
}


static int mcam_vidioc_g_ctrl(struct file *filp, void *priv,
                struct v4l2_control *ctrl)
{
        struct mcam_camera *cam = priv;
        int ret;

        mutex_lock(&cam->s_mutex);
        ret = sensor_call(cam, core, g_ctrl, ctrl);
        mutex_unlock(&cam->s_mutex);
        return ret;
}


static int mcam_vidioc_s_ctrl(struct file *filp, void *priv,
                struct v4l2_control *ctrl)
{
        struct mcam_camera *cam = priv;
        int ret;

        mutex_lock(&cam->s_mutex);
        ret = sensor_call(cam, core, s_ctrl, ctrl);
        mutex_unlock(&cam->s_mutex);
        return ret;
}


static int mcam_vidioc_querycap(struct file *file, void *priv,
                struct v4l2_capability *cap)
{
        strcpy(cap->driver, "marvell_ccic");
        strcpy(cap->card, "marvell_ccic");
        cap->version = 1;
        cap->capabilities = V4L2_CAP_VIDEO_CAPTURE |
                V4L2_CAP_READWRITE | V4L2_CAP_STREAMING;
        return 0;
}


static int mcam_vidioc_enum_fmt_vid_cap(struct file *filp,
                void *priv, struct v4l2_fmtdesc *fmt)
{
        if (fmt->index >= N_MCAM_FMTS)
                return -EINVAL;
        strlcpy(fmt->description, mcam_formats[fmt->index].desc,
                        sizeof(fmt->description));
        fmt->pixelformat = mcam_formats[fmt->index].pixelformat;
        return 0;
}

static int mcam_vidioc_try_fmt_vid_cap(struct file *filp, void *priv,
                struct v4l2_format *fmt)
{
        struct mcam_camera *cam = priv;
        struct mcam_format_struct *f;
        struct v4l2_pix_format *pix = &fmt->fmt.pix;
        struct v4l2_mbus_framefmt mbus_fmt;
        int ret;

        f = mcam_find_format(pix->pixelformat);
        pix->pixelformat = f->pixelformat;
        v4l2_fill_mbus_format(&mbus_fmt, pix, f->mbus_code);
        mutex_lock(&cam->s_mutex);
        ret = sensor_call(cam, video, try_mbus_fmt, &mbus_fmt);
        mutex_unlock(&cam->s_mutex);
        v4l2_fill_pix_format(pix, &mbus_fmt);
        pix->bytesperline = pix->width * f->bpp;
        pix->sizeimage = pix->height * pix->bytesperline;
        return ret;
}

static int mcam_vidioc_s_fmt_vid_cap(struct file *filp, void *priv,
                struct v4l2_format *fmt)
{
        struct mcam_camera *cam = priv;
        struct mcam_format_struct *f;
        int ret;

        /*
         * Can't do anything if the device is not idle
         * Also can't if there are streaming buffers in place.
         */
        if (cam->state != S_IDLE || cam->vb_queue.num_buffers > 0)
                return -EBUSY;

        f = mcam_find_format(fmt->fmt.pix.pixelformat);

        /*
         * See if the formatting works in principle.
         */
        ret = mcam_vidioc_try_fmt_vid_cap(filp, priv, fmt);
        if (ret)
                return ret;
        /*
         * Now we start to change things for real, so let's do it
         * under lock.
         */
        mutex_lock(&cam->s_mutex);
        cam->pix_format = fmt->fmt.pix;
        cam->mbus_code = f->mbus_code;

        /*
         * Make sure we have appropriate DMA buffers.
         */
        if (cam->buffer_mode == B_vmalloc) {
                ret = mcam_check_dma_buffers(cam);
                if (ret)
                        goto out;
        }
        mcam_set_config_needed(cam, 1);
        ret = 0;
out:
        mutex_unlock(&cam->s_mutex);
        return ret;
}

/*
 * Return our stored notion of how the camera is/should be configured.
 * The V4l2 spec wants us to be smarter, and actually get this from
 * the camera (and not mess with it at open time).  Someday.
 */
static int mcam_vidioc_g_fmt_vid_cap(struct file *filp, void *priv,
                struct v4l2_format *f)
{
        struct mcam_camera *cam = priv;

        f->fmt.pix = cam->pix_format;
        return 0;
}

/*
 * We only have one input - the sensor - so minimize the nonsense here.
 */
static int mcam_vidioc_enum_input(struct file *filp, void *priv,
                struct v4l2_input *input)
{
        if (input->index != 0)
                return -EINVAL;

        input->type = V4L2_INPUT_TYPE_CAMERA;
        input->std = V4L2_STD_ALL; /* Not sure what should go here */
        strcpy(input->name, "Camera");
        return 0;
}

static int mcam_vidioc_g_input(struct file *filp, void *priv, unsigned int *i)
{
        *i = 0;
        return 0;
}

static int mcam_vidioc_s_input(struct file *filp, void *priv, unsigned int i)
{
        if (i != 0)
                return -EINVAL;
        return 0;
}

/* from vivi.c */
static int mcam_vidioc_s_std(struct file *filp, void *priv, v4l2_std_id *a)
{
        return 0;
}

/*
 * G/S_PARM.  Most of this is done by the sensor, but we are
 * the level which controls the number of read buffers.
 */
static int mcam_vidioc_g_parm(struct file *filp, void *priv,
                struct v4l2_streamparm *parms)
{
        struct mcam_camera *cam = priv;
        int ret;

        mutex_lock(&cam->s_mutex);
        ret = sensor_call(cam, video, g_parm, parms);
        mutex_unlock(&cam->s_mutex);
        parms->parm.capture.readbuffers = n_dma_bufs;
        return ret;
}

static int mcam_vidioc_s_parm(struct file *filp, void *priv,
                struct v4l2_streamparm *parms)
{
        struct mcam_camera *cam = priv;
        int ret;

        mutex_lock(&cam->s_mutex);
        ret = sensor_call(cam, video, s_parm, parms);
        mutex_unlock(&cam->s_mutex);
        parms->parm.capture.readbuffers = n_dma_bufs;
        return ret;
}

static int mcam_vidioc_g_chip_ident(struct file *file, void *priv,
                struct v4l2_dbg_chip_ident *chip)
{
        struct mcam_camera *cam = priv;

        chip->ident = V4L2_IDENT_NONE;
        chip->revision = 0;
        if (v4l2_chip_match_host(&chip->match)) {
                chip->ident = cam->chip_id;
                return 0;
        }
        return sensor_call(cam, core, g_chip_ident, chip);
}

static int mcam_vidioc_enum_framesizes(struct file *filp, void *priv,
                struct v4l2_frmsizeenum *sizes)
{
        struct mcam_camera *cam = priv;
        int ret;

        mutex_lock(&cam->s_mutex);
        ret = sensor_call(cam, video, enum_framesizes, sizes);
        mutex_unlock(&cam->s_mutex);
        return ret;
}

static int mcam_vidioc_enum_frameintervals(struct file *filp, void *priv,
                struct v4l2_frmivalenum *interval)
{
        struct mcam_camera *cam = priv;
        int ret;

        mutex_lock(&cam->s_mutex);
        ret = sensor_call(cam, video, enum_frameintervals, interval);
        mutex_unlock(&cam->s_mutex);
        return ret;
}

#ifdef CONFIG_VIDEO_ADV_DEBUG
static int mcam_vidioc_g_register(struct file *file, void *priv,
                struct v4l2_dbg_register *reg)
{
        struct mcam_camera *cam = priv;

        if (v4l2_chip_match_host(&reg->match)) {
                reg->val = mcam_reg_read(cam, reg->reg);
                reg->size = 4;
                return 0;
        }
        return sensor_call(cam, core, g_register, reg);
}

static int mcam_vidioc_s_register(struct file *file, void *priv,
                struct v4l2_dbg_register *reg)
{
        struct mcam_camera *cam = priv;

        if (v4l2_chip_match_host(&reg->match)) {
                mcam_reg_write(cam, reg->reg, reg->val);
                return 0;
        }
        return sensor_call(cam, core, s_register, reg);
}
#endif

static const struct v4l2_ioctl_ops mcam_v4l_ioctl_ops = {
        .vidioc_querycap        = mcam_vidioc_querycap,
        .vidioc_enum_fmt_vid_cap = mcam_vidioc_enum_fmt_vid_cap,
        .vidioc_try_fmt_vid_cap = mcam_vidioc_try_fmt_vid_cap,
        .vidioc_s_fmt_vid_cap   = mcam_vidioc_s_fmt_vid_cap,
        .vidioc_g_fmt_vid_cap   = mcam_vidioc_g_fmt_vid_cap,
        .vidioc_enum_input      = mcam_vidioc_enum_input,
        .vidioc_g_input         = mcam_vidioc_g_input,
        .vidioc_s_input         = mcam_vidioc_s_input,
        .vidioc_s_std           = mcam_vidioc_s_std,
        .vidioc_reqbufs         = mcam_vidioc_reqbufs,
        .vidioc_querybuf        = mcam_vidioc_querybuf,
        .vidioc_qbuf            = mcam_vidioc_qbuf,
        .vidioc_dqbuf           = mcam_vidioc_dqbuf,
        .vidioc_streamon        = mcam_vidioc_streamon,
        .vidioc_streamoff       = mcam_vidioc_streamoff,
        .vidioc_queryctrl       = mcam_vidioc_queryctrl,
        .vidioc_g_ctrl          = mcam_vidioc_g_ctrl,
        .vidioc_s_ctrl          = mcam_vidioc_s_ctrl,
        .vidioc_g_parm          = mcam_vidioc_g_parm,
        .vidioc_s_parm          = mcam_vidioc_s_parm,
        .vidioc_enum_framesizes = mcam_vidioc_enum_framesizes,
        .vidioc_enum_frameintervals = mcam_vidioc_enum_frameintervals,
        .vidioc_g_chip_ident    = mcam_vidioc_g_chip_ident,
#ifdef CONFIG_VIDEO_ADV_DEBUG
        .vidioc_g_register      = mcam_vidioc_g_register,
        .vidioc_s_register      = mcam_vidioc_s_register,
#endif
};

/* ---------------------------------------------------------------------- */
/*
 * Our various file operations.
 */
static int mcam_v4l_open(struct file *filp)
{
        struct mcam_camera *cam = video_drvdata(filp);
        int ret = 0;

        filp->private_data = cam;

        frames = singles = delivered = 0;
        mutex_lock(&cam->s_mutex);
        if (cam->users == 0) {
                ret = mcam_setup_vb2(cam);
                if (ret)
                        goto out;
                mcam_ctlr_power_up(cam);
                __mcam_cam_reset(cam);
                mcam_set_config_needed(cam, 1);
        }
        (cam->users)++;
out:
        mutex_unlock(&cam->s_mutex);
        return ret;
}


static int mcam_v4l_release(struct file *filp)
{
        struct mcam_camera *cam = filp->private_data;

        cam_err(cam, "Release, %d frames, %d singles, %d delivered\n", frames,
                        singles, delivered);
        mutex_lock(&cam->s_mutex);
        (cam->users)--;
        if (filp == cam->owner) {
                mcam_ctlr_stop_dma(cam);
                cam->owner = NULL;
        }
        if (cam->users == 0) {
                mcam_cleanup_vb2(cam);
                mcam_ctlr_power_down(cam);
                if (cam->buffer_mode == B_vmalloc && alloc_bufs_at_read)
                        mcam_free_dma_bufs(cam);
        }
        mutex_unlock(&cam->s_mutex);
        return 0;
}

static ssize_t mcam_v4l_read(struct file *filp,
                char __user *buffer, size_t len, loff_t *pos)
{
        struct mcam_camera *cam = filp->private_data;
        int ret;

        mutex_lock(&cam->s_mutex);
        ret = vb2_read(&cam->vb_queue, buffer, len, pos,
                        filp->f_flags & O_NONBLOCK);
        mutex_unlock(&cam->s_mutex);
        return ret;
}



static unsigned int mcam_v4l_poll(struct file *filp,
                struct poll_table_struct *pt)
{
        struct mcam_camera *cam = filp->private_data;
        int ret;

        mutex_lock(&cam->s_mutex);
        ret = vb2_poll(&cam->vb_queue, filp, pt);
        mutex_unlock(&cam->s_mutex);
        return ret;
}


static int mcam_v4l_mmap(struct file *filp, struct vm_area_struct *vma)
{
        struct mcam_camera *cam = filp->private_data;
        int ret;

        mutex_lock(&cam->s_mutex);
        ret = vb2_mmap(&cam->vb_queue, vma);
        mutex_unlock(&cam->s_mutex);
        return ret;
}



static const struct v4l2_file_operations mcam_v4l_fops = {
        .owner = THIS_MODULE,
        .open = mcam_v4l_open,
        .release = mcam_v4l_release,
        .read = mcam_v4l_read,
        .poll = mcam_v4l_poll,
        .mmap = mcam_v4l_mmap,
        .unlocked_ioctl = video_ioctl2,
};


/*
 * This template device holds all of those v4l2 methods; we
 * clone it for specific real devices.
 */
static struct video_device mcam_v4l_template = {
        .name = "mcam",
        .tvnorms = V4L2_STD_NTSC_M,
        .current_norm = V4L2_STD_NTSC_M,  /* make mplayer happy */

        .fops = &mcam_v4l_fops,
        .ioctl_ops = &mcam_v4l_ioctl_ops,
        .release = video_device_release_empty,
};

/* ---------------------------------------------------------------------- */
/*
 * Interrupt handler stuff
 */
static void mcam_frame_complete(struct mcam_camera *cam, int frame)
{
        /*
         * Basic frame housekeeping.
         */
        set_bit(frame, &cam->flags);
        clear_bit(CF_DMA_ACTIVE, &cam->flags);
        cam->next_buf = frame;
        cam->buf_seq[frame] = ++(cam->sequence);
        frames++;
        /*
         * "This should never happen"
         */
        if (cam->state != S_STREAMING)
                return;
        /*
         * Process the frame and set up the next one.
         */
        cam->frame_complete(cam, frame);
}


/*
 * The interrupt handler; this needs to be called from the
 * platform irq handler with the lock held.
 */
int mccic_irq(struct mcam_camera *cam, unsigned int irqs)
{
        unsigned int frame, handled = 0;

        mcam_reg_write(cam, REG_IRQSTAT, FRAMEIRQS); /* Clear'em all */
        /*
         * Handle any frame completions.  There really should
         * not be more than one of these, or we have fallen
         * far behind.
         *
         * When running in S/G mode, the frame number lacks any
         * real meaning - there's only one descriptor array - but
         * the controller still picks a different one to signal
         * each time.
         */
        for (frame = 0; frame < cam->nbufs; frame++)
                if (irqs & (IRQ_EOF0 << frame)) {
                        mcam_frame_complete(cam, frame);
                        handled = 1;
                }
        /*
         * If a frame starts, note that we have DMA active.  This
         * code assumes that we won't get multiple frame interrupts
         * at once; may want to rethink that.
         */
        if (irqs & (IRQ_SOF0 | IRQ_SOF1 | IRQ_SOF2)) {
                set_bit(CF_DMA_ACTIVE, &cam->flags);
                handled = 1;
                if (cam->buffer_mode == B_DMA_sg)
                        mcam_ctlr_stop(cam);
        }
        return handled;
}

/* ---------------------------------------------------------------------- */
/*
 * Registration and such.
 */
static struct ov7670_config sensor_cfg = {
        /*
         * Exclude QCIF mode, because it only captures a tiny portion
         * of the sensor FOV
         */
        .min_width = 320,
        .min_height = 240,
};


int mccic_register(struct mcam_camera *cam)
{
        struct i2c_board_info ov7670_info = {
                .type = "ov7670",
                .addr = 0x42 >> 1,
                .platform_data = &sensor_cfg,
        };
        int ret;

        /*
         * Validate the requested buffer mode.
         */
        if (buffer_mode >= 0)
                cam->buffer_mode = buffer_mode;
        if (cam->buffer_mode == B_DMA_sg &&
                        cam->chip_id == V4L2_IDENT_CAFE) {
                printk(KERN_ERR "marvell-cam: Cafe can't do S/G I/O, "
                        "attempting vmalloc mode instead\n");
                cam->buffer_mode = B_vmalloc;
        }
        if (!mcam_buffer_mode_supported(cam->buffer_mode)) {
                printk(KERN_ERR "marvell-cam: buffer mode %d unsupported\n",
                                cam->buffer_mode);
                return -EINVAL;
        }
        /*
         * Register with V4L
         */
        ret = v4l2_device_register(cam->dev, &cam->v4l2_dev);
        if (ret)
                return ret;

        mutex_init(&cam->s_mutex);
        cam->state = S_NOTREADY;
        mcam_set_config_needed(cam, 1);
        cam->pix_format = mcam_def_pix_format;
        cam->mbus_code = mcam_def_mbus_code;
        INIT_LIST_HEAD(&cam->buffers);
        mcam_ctlr_init(cam);

        /*
         * Try to find the sensor.
         */
        sensor_cfg.clock_speed = cam->clock_speed;
        sensor_cfg.use_smbus = cam->use_smbus;
        cam->sensor_addr = ov7670_info.addr;
        cam->sensor = v4l2_i2c_new_subdev_board(&cam->v4l2_dev,
                        cam->i2c_adapter, &ov7670_info, NULL);
        if (cam->sensor == NULL) {
                ret = -ENODEV;
                goto out_unregister;
        }

        ret = mcam_cam_init(cam);
        if (ret)
                goto out_unregister;
        /*
         * Get the v4l2 setup done.
         */
        mutex_lock(&cam->s_mutex);
        cam->vdev = mcam_v4l_template;
        cam->vdev.debug = 0;
        cam->vdev.v4l2_dev = &cam->v4l2_dev;
        ret = video_register_device(&cam->vdev, VFL_TYPE_GRABBER, -1);
        if (ret)
                goto out;
        video_set_drvdata(&cam->vdev, cam);

        /*
         * If so requested, try to get our DMA buffers now.
         */
        if (cam->buffer_mode == B_vmalloc && !alloc_bufs_at_read) {
                if (mcam_alloc_dma_bufs(cam, 1))
                        cam_warn(cam, "Unable to alloc DMA buffers at load"
                                        " will try again later.");
        }

out:
        mutex_unlock(&cam->s_mutex);
        return ret;
out_unregister:
        v4l2_device_unregister(&cam->v4l2_dev);
        return ret;
}


void mccic_shutdown(struct mcam_camera *cam)
{
        /*
         * If we have no users (and we really, really should have no
         * users) the device will already be powered down.  Trying to
         * take it down again will wedge the machine, which is frowned
         * upon.
         */
        if (cam->users > 0) {
                cam_warn(cam, "Removing a device with users!\n");
                mcam_ctlr_power_down(cam);
        }
        vb2_queue_release(&cam->vb_queue);
        if (cam->buffer_mode == B_vmalloc)
                mcam_free_dma_bufs(cam);
        video_unregister_device(&cam->vdev);
        v4l2_device_unregister(&cam->v4l2_dev);
}

/*
 * Power management
 */
#ifdef CONFIG_PM

void mccic_suspend(struct mcam_camera *cam)
{
        enum mcam_state cstate = cam->state;

        mcam_ctlr_stop_dma(cam);
        mcam_ctlr_power_down(cam);
        cam->state = cstate;
}

int mccic_resume(struct mcam_camera *cam)
{
        int ret = 0;

        mutex_lock(&cam->s_mutex);
        if (cam->users > 0) {
                mcam_ctlr_power_up(cam);
                __mcam_cam_reset(cam);
        } else {
                mcam_ctlr_power_down(cam);
        }
        mutex_unlock(&cam->s_mutex);

        set_bit(CF_CONFIG_NEEDED, &cam->flags);
        if (cam->state == S_STREAMING)
                ret = mcam_read_setup(cam);
        return ret;
}
#endif /* CONFIG_PM */