/*
 * A virtual v4l2-mem2mem example device.
 *
 * This is a virtual device driver for testing mem-to-mem videobuf framework.
 * It simulates a device that uses memory buffers for both source and
 * destination, processes the data and issues an "irq" (simulated by a timer).
 * The device is capable of multi-instance, multi-buffer-per-transaction
 * operation (via the mem2mem framework).
 *
 * Copyright (c) 2009-2010 Samsung Electronics Co., Ltd.
 * Pawel Osciak, <pawel@osciak.com>
 * Marek Szyprowski, <m.szyprowski@samsung.com>
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by the
 * Free Software Foundation; either version 2 of the
 * License, or (at your option) any later version
 */
#include <linux/module.h>
#include <linux/delay.h>
#include <linux/fs.h>
#include <linux/timer.h>
#include <linux/sched.h>
#include <linux/slab.h>

#include <linux/platform_device.h>
#include <media/v4l2-mem2mem.h>
#include <media/v4l2-device.h>
#include <media/v4l2-ioctl.h>
#include <media/v4l2-ctrls.h>
#include <media/v4l2-event.h>
#include <media/videobuf2-vmalloc.h>

MODULE_DESCRIPTION("Virtual device for mem2mem framework testing");
MODULE_AUTHOR("Pawel Osciak, <pawel@osciak.com>");
MODULE_LICENSE("GPL");
MODULE_VERSION("0.1.1");
MODULE_ALIAS("mem2mem_testdev");

static unsigned debug;
module_param(debug, uint, 0644);
MODULE_PARM_DESC(debug, "activates debug info");

#define MIN_W 32
#define MIN_H 32
#define MAX_W 640
#define MAX_H 480
#define DIM_ALIGN_MASK 7 /* 8-byte alignment for line length */

/* Flags that indicate a format can be used for capture/output */
#define MEM2MEM_CAPTURE (1 << 0)
#define MEM2MEM_OUTPUT  (1 << 1)

#define MEM2MEM_NAME            "vim2m"

/* Per queue */
#define MEM2MEM_DEF_NUM_BUFS    VIDEO_MAX_FRAME
/* In bytes, per queue */
#define MEM2MEM_VID_MEM_LIMIT   (16 * 1024 * 1024)

/* Default transaction time in msec */
#define MEM2MEM_DEF_TRANSTIME   40
#define MEM2MEM_COLOR_STEP      (0xff >> 4)
#define MEM2MEM_NUM_TILES       8

/* Flags that indicate processing mode */
#define MEM2MEM_HFLIP   (1 << 0)
#define MEM2MEM_VFLIP   (1 << 1)

#define dprintk(dev, fmt, arg...) \
        v4l2_dbg(1, debug, &dev->v4l2_dev, "%s: " fmt, __func__, ## arg)


static void vim2m_dev_release(struct device *dev)
{}

static struct platform_device vim2m_pdev = {
        .name           = MEM2MEM_NAME,
        .dev.release    = vim2m_dev_release,
};

struct vim2m_fmt {
        u32     fourcc;
        int     depth;
        /* Types the format can be used for */
        u32     types;
};

static struct vim2m_fmt formats[] = {
        {
                .fourcc = V4L2_PIX_FMT_RGB565X, /* rrrrrggg gggbbbbb */
                .depth  = 16,
                /* Both capture and output format */
                .types  = MEM2MEM_CAPTURE | MEM2MEM_OUTPUT,
        },
        {
                .fourcc = V4L2_PIX_FMT_YUYV,
                .depth  = 16,
                /* Output-only format */
                .types  = MEM2MEM_OUTPUT,
        },
};

#define NUM_FORMATS ARRAY_SIZE(formats)

/* Per-queue, driver-specific private data */
struct vim2m_q_data {
        unsigned int            width;
        unsigned int            height;
        unsigned int            sizeimage;
        unsigned int            sequence;
        struct vim2m_fmt        *fmt;
};

enum {
        V4L2_M2M_SRC = 0,
        V4L2_M2M_DST = 1,
};

#define V4L2_CID_TRANS_TIME_MSEC        (V4L2_CID_USER_BASE + 0x1000)
#define V4L2_CID_TRANS_NUM_BUFS         (V4L2_CID_USER_BASE + 0x1001)

static struct vim2m_fmt *find_format(struct v4l2_format *f)
{
        struct vim2m_fmt *fmt;
        unsigned int k;

        for (k = 0; k < NUM_FORMATS; k++) {
                fmt = &formats[k];
                if (fmt->fourcc == f->fmt.pix.pixelformat)
                        break;
        }

        if (k == NUM_FORMATS)
                return NULL;

        return &formats[k];
}

struct vim2m_dev {
        struct v4l2_device      v4l2_dev;
        struct video_device     vfd;

        atomic_t                num_inst;
        struct mutex            dev_mutex;
        spinlock_t              irqlock;

        struct timer_list       timer;

        struct v4l2_m2m_dev     *m2m_dev;
};

struct vim2m_ctx {
        struct v4l2_fh          fh;
        struct vim2m_dev        *dev;

        struct v4l2_ctrl_handler hdl;

        /* Processed buffers in this transaction */
        u8                      num_processed;

        /* Transaction length (i.e. how many buffers per transaction) */
        u32                     translen;
        /* Transaction time (i.e. simulated processing time) in milliseconds */
        u32                     transtime;

        /* Abort requested by m2m */
        int                     aborting;

        /* Processing mode */
        int                     mode;

        enum v4l2_colorspace    colorspace;

        /* Source and destination queue data */
        struct vim2m_q_data   q_data[2];
};

static inline struct vim2m_ctx *file2ctx(struct file *file)
{
        return container_of(file->private_data, struct vim2m_ctx, fh);
}

static struct vim2m_q_data *get_q_data(struct vim2m_ctx *ctx,
                                         enum v4l2_buf_type type)
{
        switch (type) {
        case V4L2_BUF_TYPE_VIDEO_OUTPUT:
                return &ctx->q_data[V4L2_M2M_SRC];
        case V4L2_BUF_TYPE_VIDEO_CAPTURE:
                return &ctx->q_data[V4L2_M2M_DST];
        default:
                BUG();
        }
        return NULL;
}


static int device_process(struct vim2m_ctx *ctx,
                          struct vb2_v4l2_buffer *in_vb,
                          struct vb2_v4l2_buffer *out_vb)
{
        struct vim2m_dev *dev = ctx->dev;
        struct vim2m_q_data *q_data;
        u8 *p_in, *p_out;
        int x, y, t, w;
        int tile_w, bytes_left;
        int width, height, bytesperline;

        q_data = get_q_data(ctx, V4L2_BUF_TYPE_VIDEO_OUTPUT);

        width   = q_data->width;
        height  = q_data->height;
        bytesperline    = (q_data->width * q_data->fmt->depth) >> 3;

        p_in = vb2_plane_vaddr(&in_vb->vb2_buf, 0);
        p_out = vb2_plane_vaddr(&out_vb->vb2_buf, 0);
        if (!p_in || !p_out) {
                v4l2_err(&dev->v4l2_dev,
                         "Acquiring kernel pointers to buffers failed\n");
                return -EFAULT;
        }

        if (vb2_plane_size(&in_vb->vb2_buf, 0) >
                        vb2_plane_size(&out_vb->vb2_buf, 0)) {
                v4l2_err(&dev->v4l2_dev, "Output buffer is too small\n");
                return -EINVAL;
        }

        tile_w = (width * (q_data[V4L2_M2M_DST].fmt->depth >> 3))
                / MEM2MEM_NUM_TILES;
        bytes_left = bytesperline - tile_w * MEM2MEM_NUM_TILES;
        w = 0;

        out_vb->sequence =
                get_q_data(ctx, V4L2_BUF_TYPE_VIDEO_CAPTURE)->sequence++;
        in_vb->sequence = q_data->sequence++;
        out_vb->vb2_buf.timestamp = in_vb->vb2_buf.timestamp;

        if (in_vb->flags & V4L2_BUF_FLAG_TIMECODE)
                out_vb->timecode = in_vb->timecode;
        out_vb->field = in_vb->field;
        out_vb->flags = in_vb->flags &
                (V4L2_BUF_FLAG_TIMECODE |
                 V4L2_BUF_FLAG_KEYFRAME |
                 V4L2_BUF_FLAG_PFRAME |
                 V4L2_BUF_FLAG_BFRAME |
                 V4L2_BUF_FLAG_TSTAMP_SRC_MASK);

        switch (ctx->mode) {
        case MEM2MEM_HFLIP | MEM2MEM_VFLIP:
                p_out += bytesperline * height - bytes_left;
                for (y = 0; y < height; ++y) {
                        for (t = 0; t < MEM2MEM_NUM_TILES; ++t) {
                                if (w & 0x1) {
                                        for (x = 0; x < tile_w; ++x)
                                                *--p_out = *p_in++ +
                                                        MEM2MEM_COLOR_STEP;
                                } else {
                                        for (x = 0; x < tile_w; ++x)
                                                *--p_out = *p_in++ -
                                                        MEM2MEM_COLOR_STEP;
                                }
                                ++w;
                        }
                        p_in += bytes_left;
                        p_out -= bytes_left;
                }
                break;

        case MEM2MEM_HFLIP:
                for (y = 0; y < height; ++y) {
                        p_out += MEM2MEM_NUM_TILES * tile_w;
                        for (t = 0; t < MEM2MEM_NUM_TILES; ++t) {
                                if (w & 0x01) {
                                        for (x = 0; x < tile_w; ++x)
                                                *--p_out = *p_in++ +
                                                        MEM2MEM_COLOR_STEP;
                                } else {
                                        for (x = 0; x < tile_w; ++x)
                                                *--p_out = *p_in++ -
                                                        MEM2MEM_COLOR_STEP;
                                }
                                ++w;
                        }
                        p_in += bytes_left;
                        p_out += bytesperline;
                }
                break;

        case MEM2MEM_VFLIP:
                p_out += bytesperline * (height - 1);
                for (y = 0; y < height; ++y) {
                        for (t = 0; t < MEM2MEM_NUM_TILES; ++t) {
                                if (w & 0x1) {
                                        for (x = 0; x < tile_w; ++x)
                                                *p_out++ = *p_in++ +
                                                        MEM2MEM_COLOR_STEP;
                                } else {
                                        for (x = 0; x < tile_w; ++x)
                                                *p_out++ = *p_in++ -
                                                        MEM2MEM_COLOR_STEP;
                                }
                                ++w;
                        }
                        p_in += bytes_left;
                        p_out += bytes_left - 2 * bytesperline;
                }
                break;

        default:
                for (y = 0; y < height; ++y) {
                        for (t = 0; t < MEM2MEM_NUM_TILES; ++t) {
                                if (w & 0x1) {
                                        for (x = 0; x < tile_w; ++x)
                                                *p_out++ = *p_in++ +
                                                        MEM2MEM_COLOR_STEP;
                                } else {
                                        for (x = 0; x < tile_w; ++x)
                                                *p_out++ = *p_in++ -
                                                        MEM2MEM_COLOR_STEP;
                                }
                                ++w;
                        }
                        p_in += bytes_left;
                        p_out += bytes_left;
                }
        }

        return 0;
}

static void schedule_irq(struct vim2m_dev *dev, int msec_timeout)
{
        dprintk(dev, "Scheduling a simulated irq\n");
        mod_timer(&dev->timer, jiffies + msecs_to_jiffies(msec_timeout));
}

/*
 * mem2mem callbacks
 */

/**
 * job_ready() - check whether an instance is ready to be scheduled to run
 */
static int job_ready(void *priv)
{
        struct vim2m_ctx *ctx = priv;

        if (v4l2_m2m_num_src_bufs_ready(ctx->fh.m2m_ctx) < ctx->translen
            || v4l2_m2m_num_dst_bufs_ready(ctx->fh.m2m_ctx) < ctx->translen) {
                dprintk(ctx->dev, "Not enough buffers available\n");
                return 0;
        }

        return 1;
}

static void job_abort(void *priv)
{
        struct vim2m_ctx *ctx = priv;

        /* Will cancel the transaction in the next interrupt handler */
        ctx->aborting = 1;
}

/* device_run() - prepares and starts the device
 *
 * This simulates all the immediate preparations required before starting
 * a device. This will be called by the framework when it decides to schedule
 * a particular instance.
 */
static void device_run(void *priv)
{
        struct vim2m_ctx *ctx = priv;
        struct vim2m_dev *dev = ctx->dev;
        struct vb2_v4l2_buffer *src_buf, *dst_buf;

        src_buf = v4l2_m2m_next_src_buf(ctx->fh.m2m_ctx);
        dst_buf = v4l2_m2m_next_dst_buf(ctx->fh.m2m_ctx);

        device_process(ctx, src_buf, dst_buf);

        /* Run a timer, which simulates a hardware irq  */
        schedule_irq(dev, ctx->transtime);
}

static void device_isr(unsigned long priv)
{
        struct vim2m_dev *vim2m_dev = (struct vim2m_dev *)priv;
        struct vim2m_ctx *curr_ctx;
        struct vb2_v4l2_buffer *src_vb, *dst_vb;
        unsigned long flags;

        curr_ctx = v4l2_m2m_get_curr_priv(vim2m_dev->m2m_dev);

        if (NULL == curr_ctx) {
                pr_err("Instance released before the end of transaction\n");
                return;
        }

        src_vb = v4l2_m2m_src_buf_remove(curr_ctx->fh.m2m_ctx);
        dst_vb = v4l2_m2m_dst_buf_remove(curr_ctx->fh.m2m_ctx);

        curr_ctx->num_processed++;

        spin_lock_irqsave(&vim2m_dev->irqlock, flags);
        v4l2_m2m_buf_done(src_vb, VB2_BUF_STATE_DONE);
        v4l2_m2m_buf_done(dst_vb, VB2_BUF_STATE_DONE);
        spin_unlock_irqrestore(&vim2m_dev->irqlock, flags);

        if (curr_ctx->num_processed == curr_ctx->translen
            || curr_ctx->aborting) {
                dprintk(curr_ctx->dev, "Finishing transaction\n");
                curr_ctx->num_processed = 0;
                v4l2_m2m_job_finish(vim2m_dev->m2m_dev, curr_ctx->fh.m2m_ctx);
        } else {
                device_run(curr_ctx);
        }
}

/*
 * video ioctls
 */
static int vidioc_querycap(struct file *file, void *priv,
                           struct v4l2_capability *cap)
{
        strncpy(cap->driver, MEM2MEM_NAME, sizeof(cap->driver) - 1);
        strncpy(cap->card, MEM2MEM_NAME, sizeof(cap->card) - 1);
        snprintf(cap->bus_info, sizeof(cap->bus_info),
                        "platform:%s", MEM2MEM_NAME);
        cap->device_caps = V4L2_CAP_VIDEO_M2M | V4L2_CAP_STREAMING;
        cap->capabilities = cap->device_caps | V4L2_CAP_DEVICE_CAPS;
        return 0;
}

static int enum_fmt(struct v4l2_fmtdesc *f, u32 type)
{
        int i, num;
        struct vim2m_fmt *fmt;

        num = 0;

        for (i = 0; i < NUM_FORMATS; ++i) {
                if (formats[i].types & type) {
                        /* index-th format of type type found ? */
                        if (num == f->index)
                                break;
                        /* Correct type but haven't reached our index yet,
                         * just increment per-type index */
                        ++num;
                }
        }

        if (i < NUM_FORMATS) {
                /* Format found */
                fmt = &formats[i];
                f->pixelformat = fmt->fourcc;
                return 0;
        }

        /* Format not found */
        return -EINVAL;
}

static int vidioc_enum_fmt_vid_cap(struct file *file, void *priv,
                                   struct v4l2_fmtdesc *f)
{
        return enum_fmt(f, MEM2MEM_CAPTURE);
}

static int vidioc_enum_fmt_vid_out(struct file *file, void *priv,
                                   struct v4l2_fmtdesc *f)
{
        return enum_fmt(f, MEM2MEM_OUTPUT);
}

static int vidioc_g_fmt(struct vim2m_ctx *ctx, struct v4l2_format *f)
{
        struct vb2_queue *vq;
        struct vim2m_q_data *q_data;

        vq = v4l2_m2m_get_vq(ctx->fh.m2m_ctx, f->type);
        if (!vq)
                return -EINVAL;

        q_data = get_q_data(ctx, f->type);

        f->fmt.pix.width        = q_data->width;
        f->fmt.pix.height       = q_data->height;
        f->fmt.pix.field        = V4L2_FIELD_NONE;
        f->fmt.pix.pixelformat  = q_data->fmt->fourcc;
        f->fmt.pix.bytesperline = (q_data->width * q_data->fmt->depth) >> 3;
        f->fmt.pix.sizeimage    = q_data->sizeimage;
        f->fmt.pix.colorspace   = ctx->colorspace;

        return 0;
}

static int vidioc_g_fmt_vid_out(struct file *file, void *priv,
                                struct v4l2_format *f)
{
        return vidioc_g_fmt(file2ctx(file), f);
}

static int vidioc_g_fmt_vid_cap(struct file *file, void *priv,
                                struct v4l2_format *f)
{
        return vidioc_g_fmt(file2ctx(file), f);
}

static int vidioc_try_fmt(struct v4l2_format *f, struct vim2m_fmt *fmt)
{
        /* V4L2 specification suggests the driver corrects the format struct
         * if any of the dimensions is unsupported */
        if (f->fmt.pix.height < MIN_H)
                f->fmt.pix.height = MIN_H;
        else if (f->fmt.pix.height > MAX_H)
                f->fmt.pix.height = MAX_H;

        if (f->fmt.pix.width < MIN_W)
                f->fmt.pix.width = MIN_W;
        else if (f->fmt.pix.width > MAX_W)
                f->fmt.pix.width = MAX_W;

        f->fmt.pix.width &= ~DIM_ALIGN_MASK;
        f->fmt.pix.bytesperline = (f->fmt.pix.width * fmt->depth) >> 3;
        f->fmt.pix.sizeimage = f->fmt.pix.height * f->fmt.pix.bytesperline;
        f->fmt.pix.field = V4L2_FIELD_NONE;

        return 0;
}

static int vidioc_try_fmt_vid_cap(struct file *file, void *priv,
                                  struct v4l2_format *f)
{
        struct vim2m_fmt *fmt;
        struct vim2m_ctx *ctx = file2ctx(file);

        fmt = find_format(f);
        if (!fmt) {
                f->fmt.pix.pixelformat = formats[0].fourcc;
                fmt = find_format(f);
        }
        if (!(fmt->types & MEM2MEM_CAPTURE)) {
                v4l2_err(&ctx->dev->v4l2_dev,
                         "Fourcc format (0x%08x) invalid.\n",
                         f->fmt.pix.pixelformat);
                return -EINVAL;
        }
        f->fmt.pix.colorspace = ctx->colorspace;

        return vidioc_try_fmt(f, fmt);
}

static int vidioc_try_fmt_vid_out(struct file *file, void *priv,
                                  struct v4l2_format *f)
{
        struct vim2m_fmt *fmt;
        struct vim2m_ctx *ctx = file2ctx(file);

        fmt = find_format(f);
        if (!fmt) {
                f->fmt.pix.pixelformat = formats[0].fourcc;
                fmt = find_format(f);
        }
        if (!(fmt->types & MEM2MEM_OUTPUT)) {
                v4l2_err(&ctx->dev->v4l2_dev,
                         "Fourcc format (0x%08x) invalid.\n",
                         f->fmt.pix.pixelformat);
                return -EINVAL;
        }
        if (!f->fmt.pix.colorspace)
                f->fmt.pix.colorspace = V4L2_COLORSPACE_REC709;

        return vidioc_try_fmt(f, fmt);
}

static int vidioc_s_fmt(struct vim2m_ctx *ctx, struct v4l2_format *f)
{
        struct vim2m_q_data *q_data;
        struct vb2_queue *vq;

        vq = v4l2_m2m_get_vq(ctx->fh.m2m_ctx, f->type);
        if (!vq)
                return -EINVAL;

        q_data = get_q_data(ctx, f->type);
        if (!q_data)
                return -EINVAL;

        if (vb2_is_busy(vq)) {
                v4l2_err(&ctx->dev->v4l2_dev, "%s queue busy\n", __func__);
                return -EBUSY;
        }

        q_data->fmt             = find_format(f);
        q_data->width           = f->fmt.pix.width;
        q_data->height          = f->fmt.pix.height;
        q_data->sizeimage       = q_data->width * q_data->height
                                * q_data->fmt->depth >> 3;

        dprintk(ctx->dev,
                "Setting format for type %d, wxh: %dx%d, fmt: %d\n",
                f->type, q_data->width, q_data->height, q_data->fmt->fourcc);

        return 0;
}

static int vidioc_s_fmt_vid_cap(struct file *file, void *priv,
                                struct v4l2_format *f)
{
        int ret;

        ret = vidioc_try_fmt_vid_cap(file, priv, f);
        if (ret)
                return ret;

        return vidioc_s_fmt(file2ctx(file), f);
}

static int vidioc_s_fmt_vid_out(struct file *file, void *priv,
                                struct v4l2_format *f)
{
        struct vim2m_ctx *ctx = file2ctx(file);
        int ret;

        ret = vidioc_try_fmt_vid_out(file, priv, f);
        if (ret)
                return ret;

        ret = vidioc_s_fmt(file2ctx(file), f);
        if (!ret)
                ctx->colorspace = f->fmt.pix.colorspace;
        return ret;
}

static int vim2m_s_ctrl(struct v4l2_ctrl *ctrl)
{
        struct vim2m_ctx *ctx =
                container_of(ctrl->handler, struct vim2m_ctx, hdl);

        switch (ctrl->id) {
        case V4L2_CID_HFLIP:
                if (ctrl->val)
                        ctx->mode |= MEM2MEM_HFLIP;
                else
                        ctx->mode &= ~MEM2MEM_HFLIP;
                break;

        case V4L2_CID_VFLIP:
                if (ctrl->val)
                        ctx->mode |= MEM2MEM_VFLIP;
                else
                        ctx->mode &= ~MEM2MEM_VFLIP;
                break;

        case V4L2_CID_TRANS_TIME_MSEC:
                ctx->transtime = ctrl->val;
                break;

        case V4L2_CID_TRANS_NUM_BUFS:
                ctx->translen = ctrl->val;
                break;

        default:
                v4l2_err(&ctx->dev->v4l2_dev, "Invalid control\n");
                return -EINVAL;
        }

        return 0;
}

static const struct v4l2_ctrl_ops vim2m_ctrl_ops = {
        .s_ctrl = vim2m_s_ctrl,
};


static const struct v4l2_ioctl_ops vim2m_ioctl_ops = {
        .vidioc_querycap        = vidioc_querycap,

        .vidioc_enum_fmt_vid_cap = vidioc_enum_fmt_vid_cap,
        .vidioc_g_fmt_vid_cap   = vidioc_g_fmt_vid_cap,
        .vidioc_try_fmt_vid_cap = vidioc_try_fmt_vid_cap,
        .vidioc_s_fmt_vid_cap   = vidioc_s_fmt_vid_cap,

        .vidioc_enum_fmt_vid_out = vidioc_enum_fmt_vid_out,
        .vidioc_g_fmt_vid_out   = vidioc_g_fmt_vid_out,
        .vidioc_try_fmt_vid_out = vidioc_try_fmt_vid_out,
        .vidioc_s_fmt_vid_out   = vidioc_s_fmt_vid_out,

        .vidioc_reqbufs         = v4l2_m2m_ioctl_reqbufs,
        .vidioc_querybuf        = v4l2_m2m_ioctl_querybuf,
        .vidioc_qbuf            = v4l2_m2m_ioctl_qbuf,
        .vidioc_dqbuf           = v4l2_m2m_ioctl_dqbuf,
        .vidioc_prepare_buf     = v4l2_m2m_ioctl_prepare_buf,
        .vidioc_create_bufs     = v4l2_m2m_ioctl_create_bufs,
        .vidioc_expbuf          = v4l2_m2m_ioctl_expbuf,

        .vidioc_streamon        = v4l2_m2m_ioctl_streamon,
        .vidioc_streamoff       = v4l2_m2m_ioctl_streamoff,

        .vidioc_subscribe_event = v4l2_ctrl_subscribe_event,
        .vidioc_unsubscribe_event = v4l2_event_unsubscribe,
};


/*
 * Queue operations
 */

static int vim2m_queue_setup(struct vb2_queue *vq,
                                unsigned int *nbuffers, unsigned int *nplanes,
                                unsigned int sizes[], void *alloc_ctxs[])
{
        struct vim2m_ctx *ctx = vb2_get_drv_priv(vq);
        struct vim2m_q_data *q_data;
        unsigned int size, count = *nbuffers;

        q_data = get_q_data(ctx, vq->type);

        size = q_data->width * q_data->height * q_data->fmt->depth >> 3;

        while (size * count > MEM2MEM_VID_MEM_LIMIT)
                (count)--;
        *nbuffers = count;

        if (*nplanes)
                return sizes[0] < size ? -EINVAL : 0;

        *nplanes = 1;
        sizes[0] = size;

        /*
         * videobuf2-vmalloc allocator is context-less so no need to set
         * alloc_ctxs array.
         */

        dprintk(ctx->dev, "get %d buffer(s) of size %d each.\n", count, size);

        return 0;
}

static int vim2m_buf_prepare(struct vb2_buffer *vb)
{
        struct vb2_v4l2_buffer *vbuf = to_vb2_v4l2_buffer(vb);
        struct vim2m_ctx *ctx = vb2_get_drv_priv(vb->vb2_queue);
        struct vim2m_q_data *q_data;

        dprintk(ctx->dev, "type: %d\n", vb->vb2_queue->type);

        q_data = get_q_data(ctx, vb->vb2_queue->type);
        if (V4L2_TYPE_IS_OUTPUT(vb->vb2_queue->type)) {
                if (vbuf->field == V4L2_FIELD_ANY)
                        vbuf->field = V4L2_FIELD_NONE;
                if (vbuf->field != V4L2_FIELD_NONE) {
                        dprintk(ctx->dev, "%s field isn't supported\n",
                                        __func__);
                        return -EINVAL;
                }
        }

        if (vb2_plane_size(vb, 0) < q_data->sizeimage) {
                dprintk(ctx->dev, "%s data will not fit into plane (%lu < %lu)\n",
                                __func__, vb2_plane_size(vb, 0), (long)q_data->sizeimage);
                return -EINVAL;
        }

        vb2_set_plane_payload(vb, 0, q_data->sizeimage);

        return 0;
}

static void vim2m_buf_queue(struct vb2_buffer *vb)
{
        struct vb2_v4l2_buffer *vbuf = to_vb2_v4l2_buffer(vb);
        struct vim2m_ctx *ctx = vb2_get_drv_priv(vb->vb2_queue);

        v4l2_m2m_buf_queue(ctx->fh.m2m_ctx, vbuf);
}

static int vim2m_start_streaming(struct vb2_queue *q, unsigned count)
{
        struct vim2m_ctx *ctx = vb2_get_drv_priv(q);
        struct vim2m_q_data *q_data = get_q_data(ctx, q->type);

        q_data->sequence = 0;
        return 0;
}

static void vim2m_stop_streaming(struct vb2_queue *q)
{
        struct vim2m_ctx *ctx = vb2_get_drv_priv(q);
        struct vb2_v4l2_buffer *vbuf;
        unsigned long flags;

        for (;;) {
                if (V4L2_TYPE_IS_OUTPUT(q->type))
                        vbuf = v4l2_m2m_src_buf_remove(ctx->fh.m2m_ctx);
                else
                        vbuf = v4l2_m2m_dst_buf_remove(ctx->fh.m2m_ctx);
                if (vbuf == NULL)
                        return;
                spin_lock_irqsave(&ctx->dev->irqlock, flags);
                v4l2_m2m_buf_done(vbuf, VB2_BUF_STATE_ERROR);
                spin_unlock_irqrestore(&ctx->dev->irqlock, flags);
        }
}

static struct vb2_ops vim2m_qops = {
        .queue_setup     = vim2m_queue_setup,
        .buf_prepare     = vim2m_buf_prepare,
        .buf_queue       = vim2m_buf_queue,
        .start_streaming = vim2m_start_streaming,
        .stop_streaming  = vim2m_stop_streaming,
        .wait_prepare    = vb2_ops_wait_prepare,
        .wait_finish     = vb2_ops_wait_finish,
};

static int queue_init(void *priv, struct vb2_queue *src_vq, struct vb2_queue *dst_vq)
{
        struct vim2m_ctx *ctx = priv;
        int ret;

        src_vq->type = V4L2_BUF_TYPE_VIDEO_OUTPUT;
        src_vq->io_modes = VB2_MMAP | VB2_USERPTR | VB2_DMABUF;
        src_vq->drv_priv = ctx;
        src_vq->buf_struct_size = sizeof(struct v4l2_m2m_buffer);
        src_vq->ops = &vim2m_qops;
        src_vq->mem_ops = &vb2_vmalloc_memops;
        src_vq->timestamp_flags = V4L2_BUF_FLAG_TIMESTAMP_COPY;
        src_vq->lock = &ctx->dev->dev_mutex;

        ret = vb2_queue_init(src_vq);
        if (ret)
                return ret;

        dst_vq->type = V4L2_BUF_TYPE_VIDEO_CAPTURE;
        dst_vq->io_modes = VB2_MMAP | VB2_USERPTR | VB2_DMABUF;
        dst_vq->drv_priv = ctx;
        dst_vq->buf_struct_size = sizeof(struct v4l2_m2m_buffer);
        dst_vq->ops = &vim2m_qops;
        dst_vq->mem_ops = &vb2_vmalloc_memops;
        dst_vq->timestamp_flags = V4L2_BUF_FLAG_TIMESTAMP_COPY;
        dst_vq->lock = &ctx->dev->dev_mutex;

        return vb2_queue_init(dst_vq);
}

static const struct v4l2_ctrl_config vim2m_ctrl_trans_time_msec = {
        .ops = &vim2m_ctrl_ops,
        .id = V4L2_CID_TRANS_TIME_MSEC,
        .name = "Transaction Time (msec)",
        .type = V4L2_CTRL_TYPE_INTEGER,
        .def = MEM2MEM_DEF_TRANSTIME,
        .min = 1,
        .max = 10001,
        .step = 1,
};

static const struct v4l2_ctrl_config vim2m_ctrl_trans_num_bufs = {
        .ops = &vim2m_ctrl_ops,
        .id = V4L2_CID_TRANS_NUM_BUFS,
        .name = "Buffers Per Transaction",
        .type = V4L2_CTRL_TYPE_INTEGER,
        .def = 1,
        .min = 1,
        .max = MEM2MEM_DEF_NUM_BUFS,
        .step = 1,
};

/*
 * File operations
 */
static int vim2m_open(struct file *file)
{
        struct vim2m_dev *dev = video_drvdata(file);
        struct vim2m_ctx *ctx = NULL;
        struct v4l2_ctrl_handler *hdl;
        int rc = 0;

        if (mutex_lock_interruptible(&dev->dev_mutex))
                return -ERESTARTSYS;
        ctx = kzalloc(sizeof(*ctx), GFP_KERNEL);
        if (!ctx) {
                rc = -ENOMEM;
                goto open_unlock;
        }

        v4l2_fh_init(&ctx->fh, video_devdata(file));
        file->private_data = &ctx->fh;
        ctx->dev = dev;
        hdl = &ctx->hdl;
        v4l2_ctrl_handler_init(hdl, 4);
        v4l2_ctrl_new_std(hdl, &vim2m_ctrl_ops, V4L2_CID_HFLIP, 0, 1, 1, 0);
        v4l2_ctrl_new_std(hdl, &vim2m_ctrl_ops, V4L2_CID_VFLIP, 0, 1, 1, 0);
        v4l2_ctrl_new_custom(hdl, &vim2m_ctrl_trans_time_msec, NULL);
        v4l2_ctrl_new_custom(hdl, &vim2m_ctrl_trans_num_bufs, NULL);
        if (hdl->error) {
                rc = hdl->error;
                v4l2_ctrl_handler_free(hdl);
                goto open_unlock;
        }
        ctx->fh.ctrl_handler = hdl;
        v4l2_ctrl_handler_setup(hdl);

        ctx->q_data[V4L2_M2M_SRC].fmt = &formats[0];
        ctx->q_data[V4L2_M2M_SRC].width = 640;
        ctx->q_data[V4L2_M2M_SRC].height = 480;
        ctx->q_data[V4L2_M2M_SRC].sizeimage =
                ctx->q_data[V4L2_M2M_SRC].width *
                ctx->q_data[V4L2_M2M_SRC].height *
                (ctx->q_data[V4L2_M2M_SRC].fmt->depth >> 3);
        ctx->q_data[V4L2_M2M_DST] = ctx->q_data[V4L2_M2M_SRC];
        ctx->colorspace = V4L2_COLORSPACE_REC709;

        ctx->fh.m2m_ctx = v4l2_m2m_ctx_init(dev->m2m_dev, ctx, &queue_init);

        if (IS_ERR(ctx->fh.m2m_ctx)) {
                rc = PTR_ERR(ctx->fh.m2m_ctx);

                v4l2_ctrl_handler_free(hdl);
                kfree(ctx);
                goto open_unlock;
        }

        v4l2_fh_add(&ctx->fh);
        atomic_inc(&dev->num_inst);

        dprintk(dev, "Created instance: %p, m2m_ctx: %p\n",
                ctx, ctx->fh.m2m_ctx);

open_unlock:
        mutex_unlock(&dev->dev_mutex);
        return rc;
}

static int vim2m_release(struct file *file)
{
        struct vim2m_dev *dev = video_drvdata(file);
        struct vim2m_ctx *ctx = file2ctx(file);

        dprintk(dev, "Releasing instance %p\n", ctx);

        v4l2_fh_del(&ctx->fh);
        v4l2_fh_exit(&ctx->fh);
        v4l2_ctrl_handler_free(&ctx->hdl);
        mutex_lock(&dev->dev_mutex);
        v4l2_m2m_ctx_release(ctx->fh.m2m_ctx);
        mutex_unlock(&dev->dev_mutex);
        kfree(ctx);

        atomic_dec(&dev->num_inst);

        return 0;
}

static const struct v4l2_file_operations vim2m_fops = {
        .owner          = THIS_MODULE,
        .open           = vim2m_open,
        .release        = vim2m_release,
        .poll           = v4l2_m2m_fop_poll,
        .unlocked_ioctl = video_ioctl2,
        .mmap           = v4l2_m2m_fop_mmap,
};

static struct video_device vim2m_videodev = {
        .name           = MEM2MEM_NAME,
        .vfl_dir        = VFL_DIR_M2M,
        .fops           = &vim2m_fops,
        .ioctl_ops      = &vim2m_ioctl_ops,
        .minor          = -1,
        .release        = video_device_release_empty,
};

static struct v4l2_m2m_ops m2m_ops = {
        .device_run     = device_run,
        .job_ready      = job_ready,
        .job_abort      = job_abort,
};

static int vim2m_probe(struct platform_device *pdev)
{
        struct vim2m_dev *dev;
        struct video_device *vfd;
        int ret;

        dev = devm_kzalloc(&pdev->dev, sizeof(*dev), GFP_KERNEL);
        if (!dev)
                return -ENOMEM;

        spin_lock_init(&dev->irqlock);

        ret = v4l2_device_register(&pdev->dev, &dev->v4l2_dev);
        if (ret)
                return ret;

        atomic_set(&dev->num_inst, 0);
        mutex_init(&dev->dev_mutex);

        dev->vfd = vim2m_videodev;
        vfd = &dev->vfd;
        vfd->lock = &dev->dev_mutex;
        vfd->v4l2_dev = &dev->v4l2_dev;

        ret = video_register_device(vfd, VFL_TYPE_GRABBER, 0);
        if (ret) {
                v4l2_err(&dev->v4l2_dev, "Failed to register video device\n");
                goto unreg_dev;
        }

        video_set_drvdata(vfd, dev);
        snprintf(vfd->name, sizeof(vfd->name), "%s", vim2m_videodev.name);
        v4l2_info(&dev->v4l2_dev,
                        "Device registered as /dev/video%d\n", vfd->num);

        setup_timer(&dev->timer, device_isr, (long)dev);
        platform_set_drvdata(pdev, dev);

        dev->m2m_dev = v4l2_m2m_init(&m2m_ops);
        if (IS_ERR(dev->m2m_dev)) {
                v4l2_err(&dev->v4l2_dev, "Failed to init mem2mem device\n");
                ret = PTR_ERR(dev->m2m_dev);
                goto err_m2m;
        }

        return 0;

err_m2m:
        v4l2_m2m_release(dev->m2m_dev);
        video_unregister_device(&dev->vfd);
unreg_dev:
        v4l2_device_unregister(&dev->v4l2_dev);

        return ret;
}

static int vim2m_remove(struct platform_device *pdev)
{
        struct vim2m_dev *dev = platform_get_drvdata(pdev);

        v4l2_info(&dev->v4l2_dev, "Removing " MEM2MEM_NAME);
        v4l2_m2m_release(dev->m2m_dev);
        del_timer_sync(&dev->timer);
        video_unregister_device(&dev->vfd);
        v4l2_device_unregister(&dev->v4l2_dev);

        return 0;
}

static struct platform_driver vim2m_pdrv = {
        .probe          = vim2m_probe,
        .remove         = vim2m_remove,
        .driver         = {
                .name   = MEM2MEM_NAME,
        },
};

static void __exit vim2m_exit(void)
{
        platform_driver_unregister(&vim2m_pdrv);
        platform_device_unregister(&vim2m_pdev);
}

static int __init vim2m_init(void)
{
        int ret;

        ret = platform_device_register(&vim2m_pdev);
        if (ret)
                return ret;

        ret = platform_driver_register(&vim2m_pdrv);
        if (ret)
                platform_device_unregister(&vim2m_pdev);

        return ret;
}

module_init(vim2m_init);
module_exit(vim2m_exit);