gsc-m2m.c

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/*
 * Copyright (c) 2011 - 2012 Samsung Electronics Co., Ltd.
 *      http://www.samsung.com
 *
 * Samsung EXYNOS5 SoC series G-Scaler driver
 *
 * 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/kernel.h>
#include <linux/types.h>
#include <linux/errno.h>
#include <linux/bug.h>
#include <linux/interrupt.h>
#include <linux/workqueue.h>
#include <linux/device.h>
#include <linux/platform_device.h>
#include <linux/list.h>
#include <linux/io.h>
#include <linux/slab.h>
#include <linux/clk.h>

#include <media/v4l2-ioctl.h>

#include "gsc-core.h"

static int gsc_m2m_ctx_stop_req(struct gsc_ctx *ctx)
{
    struct gsc_ctx *curr_ctx;
    struct gsc_dev *gsc = ctx->gsc_dev;
    int ret;

    curr_ctx = v4l2_m2m_get_curr_priv(gsc->m2m.m2m_dev);
    if (!gsc_m2m_pending(gsc) || (curr_ctx != ctx))
        return 0;

    gsc_ctx_state_lock_set(GSC_CTX_STOP_REQ, ctx);
    ret = wait_event_timeout(gsc->irq_queue,
            !gsc_ctx_state_is_set(GSC_CTX_STOP_REQ, ctx),
            GSC_SHUTDOWN_TIMEOUT);

    return ret == 0 ? -ETIMEDOUT : ret;
}

static int gsc_m2m_start_streaming(struct vb2_queue *q, unsigned int count)
{
    struct gsc_ctx *ctx = q->drv_priv;
    int ret;

    ret = pm_runtime_get_sync(&ctx->gsc_dev->pdev->dev);
    return ret > 0 ? 0 : ret;
}

static int gsc_m2m_stop_streaming(struct vb2_queue *q)
{
    struct gsc_ctx *ctx = q->drv_priv;
    int ret;

    ret = gsc_m2m_ctx_stop_req(ctx);
    if (ret == -ETIMEDOUT)
        gsc_m2m_job_finish(ctx, VB2_BUF_STATE_ERROR);

    pm_runtime_put(&ctx->gsc_dev->pdev->dev);

    return 0;
}

void gsc_m2m_job_finish(struct gsc_ctx *ctx, int vb_state)
{
    struct vb2_buffer *src_vb, *dst_vb;

    if (!ctx || !ctx->m2m_ctx)
        return;

    src_vb = v4l2_m2m_src_buf_remove(ctx->m2m_ctx);
    dst_vb = v4l2_m2m_dst_buf_remove(ctx->m2m_ctx);

    if (src_vb && dst_vb) {
        v4l2_m2m_buf_done(src_vb, vb_state);
        v4l2_m2m_buf_done(dst_vb, vb_state);

        v4l2_m2m_job_finish(ctx->gsc_dev->m2m.m2m_dev,
                    ctx->m2m_ctx);
    }
}


static void gsc_m2m_job_abort(void *priv)
{
    struct gsc_ctx *ctx = priv;
    int ret;

    ret = gsc_m2m_ctx_stop_req(ctx);
    if (ret == -ETIMEDOUT)
        gsc_m2m_job_finish(ctx, VB2_BUF_STATE_ERROR);
}

static int gsc_fill_addr(struct gsc_ctx *ctx)
{
    struct gsc_frame *s_frame, *d_frame;
    struct vb2_buffer *vb = NULL;
    int ret;

    s_frame = &ctx->s_frame;
    d_frame = &ctx->d_frame;

    vb = v4l2_m2m_next_src_buf(ctx->m2m_ctx);
    ret = gsc_prepare_addr(ctx, vb, s_frame, &s_frame->addr);
    if (ret)
        return ret;

    vb = v4l2_m2m_next_dst_buf(ctx->m2m_ctx);
    return gsc_prepare_addr(ctx, vb, d_frame, &d_frame->addr);
}

static void gsc_m2m_device_run(void *priv)
{
    struct gsc_ctx *ctx = priv;
    struct gsc_dev *gsc;
    unsigned long flags;
    u32 ret;
    bool is_set = false;

    if (WARN(!ctx, "null hardware context\n"))
        return;

    gsc = ctx->gsc_dev;
    spin_lock_irqsave(&gsc->slock, flags);

    set_bit(ST_M2M_PEND, &gsc->state);

    /* Reconfigure hardware if the context has changed. */
    if (gsc->m2m.ctx != ctx) {
        pr_debug("gsc->m2m.ctx = 0x%p, current_ctx = 0x%p",
                gsc->m2m.ctx, ctx);
        ctx->state |= GSC_PARAMS;
        gsc->m2m.ctx = ctx;
    }

    is_set = (ctx->state & GSC_CTX_STOP_REQ) ? 1 : 0;
    ctx->state &= ~GSC_CTX_STOP_REQ;
    if (is_set) {
        wake_up(&gsc->irq_queue);
        goto put_device;
    }

    ret = gsc_fill_addr(ctx);
    if (ret) {
        pr_err("Wrong address");
        goto put_device;
    }

    gsc_set_prefbuf(gsc, &ctx->s_frame);
    gsc_hw_set_input_addr(gsc, &ctx->s_frame.addr, GSC_M2M_BUF_NUM);
    gsc_hw_set_output_addr(gsc, &ctx->d_frame.addr, GSC_M2M_BUF_NUM);

    if (ctx->state & GSC_PARAMS) {
        gsc_hw_set_input_buf_masking(gsc, GSC_M2M_BUF_NUM, false);
        gsc_hw_set_output_buf_masking(gsc, GSC_M2M_BUF_NUM, false);
        gsc_hw_set_frm_done_irq_mask(gsc, false);
        gsc_hw_set_gsc_irq_enable(gsc, true);

        if (gsc_set_scaler_info(ctx)) {
            pr_err("Scaler setup error");
            goto put_device;
        }

        gsc_hw_set_input_path(ctx);
        gsc_hw_set_in_size(ctx);
        gsc_hw_set_in_image_format(ctx);

        gsc_hw_set_output_path(ctx);
        gsc_hw_set_out_size(ctx);
        gsc_hw_set_out_image_format(ctx);

        gsc_hw_set_prescaler(ctx);
        gsc_hw_set_mainscaler(ctx);
        gsc_hw_set_rotation(ctx);
        gsc_hw_set_global_alpha(ctx);
    }

    /* update shadow registers */
    gsc_hw_set_sfr_update(ctx);

    ctx->state &= ~GSC_PARAMS;
    gsc_hw_enable_control(gsc, true);

    spin_unlock_irqrestore(&gsc->slock, flags);
    return;

put_device:
    ctx->state &= ~GSC_PARAMS;
    spin_unlock_irqrestore(&gsc->slock, flags);
}

static int gsc_m2m_queue_setup(struct vb2_queue *vq,
            const struct v4l2_format *fmt,
            unsigned int *num_buffers, unsigned int *num_planes,
            unsigned int sizes[], void *allocators[])
{
    struct gsc_ctx *ctx = vb2_get_drv_priv(vq);
    struct gsc_frame *frame;
    int i;

    frame = ctx_get_frame(ctx, vq->type);
    if (IS_ERR(frame))
        return PTR_ERR(frame);

    if (!frame->fmt)
        return -EINVAL;

    *num_planes = frame->fmt->num_planes;
    for (i = 0; i < frame->fmt->num_planes; i++) {
        sizes[i] = frame->payload[i];
        allocators[i] = ctx->gsc_dev->alloc_ctx;
    }
    return 0;
}

static int gsc_m2m_buf_prepare(struct vb2_buffer *vb)
{
    struct gsc_ctx *ctx = vb2_get_drv_priv(vb->vb2_queue);
    struct gsc_frame *frame;
    int i;

    frame = ctx_get_frame(ctx, vb->vb2_queue->type);
    if (IS_ERR(frame))
        return PTR_ERR(frame);

    if (!V4L2_TYPE_IS_OUTPUT(vb->vb2_queue->type)) {
        for (i = 0; i < frame->fmt->num_planes; i++)
            vb2_set_plane_payload(vb, i, frame->payload[i]);
    }

    return 0;
}

static void gsc_m2m_buf_queue(struct vb2_buffer *vb)
{
    struct gsc_ctx *ctx = vb2_get_drv_priv(vb->vb2_queue);

    pr_debug("ctx: %p, ctx->state: 0x%x", ctx, ctx->state);

    if (ctx->m2m_ctx)
        v4l2_m2m_buf_queue(ctx->m2m_ctx, vb);
}

static struct vb2_ops gsc_m2m_qops = {
    .queue_setup     = gsc_m2m_queue_setup,
    .buf_prepare     = gsc_m2m_buf_prepare,
    .buf_queue   = gsc_m2m_buf_queue,
    .wait_prepare    = gsc_unlock,
    .wait_finish     = gsc_lock,
    .stop_streaming  = gsc_m2m_stop_streaming,
    .start_streaming = gsc_m2m_start_streaming,
};

static int gsc_m2m_querycap(struct file *file, void *fh,
               struct v4l2_capability *cap)
{
    struct gsc_ctx *ctx = fh_to_ctx(fh);
    struct gsc_dev *gsc = ctx->gsc_dev;

    strlcpy(cap->driver, gsc->pdev->name, sizeof(cap->driver));
    strlcpy(cap->card, gsc->pdev->name, sizeof(cap->card));
    strlcpy(cap->bus_info, "platform", sizeof(cap->bus_info));
    cap->device_caps = V4L2_CAP_STREAMING | V4L2_CAP_VIDEO_M2M_MPLANE |
        V4L2_CAP_VIDEO_CAPTURE_MPLANE | V4L2_CAP_VIDEO_OUTPUT_MPLANE;

    cap->capabilities = cap->device_caps | V4L2_CAP_DEVICE_CAPS;
    return 0;
}

static int gsc_m2m_enum_fmt_mplane(struct file *file, void *priv,
                struct v4l2_fmtdesc *f)
{
    return gsc_enum_fmt_mplane(f);
}

static int gsc_m2m_g_fmt_mplane(struct file *file, void *fh,
                 struct v4l2_format *f)
{
    struct gsc_ctx *ctx = fh_to_ctx(fh);

    return gsc_g_fmt_mplane(ctx, f);
}

static int gsc_m2m_try_fmt_mplane(struct file *file, void *fh,
                  struct v4l2_format *f)
{
    struct gsc_ctx *ctx = fh_to_ctx(fh);

    return gsc_try_fmt_mplane(ctx, f);
}

static int gsc_m2m_s_fmt_mplane(struct file *file, void *fh,
                 struct v4l2_format *f)
{
    struct gsc_ctx *ctx = fh_to_ctx(fh);
    struct vb2_queue *vq;
    struct gsc_frame *frame;
    struct v4l2_pix_format_mplane *pix;
    int i, ret = 0;

    ret = gsc_m2m_try_fmt_mplane(file, fh, f);
    if (ret)
        return ret;

    vq = v4l2_m2m_get_vq(ctx->m2m_ctx, f->type);

    if (vb2_is_streaming(vq)) {
        pr_err("queue (%d) busy", f->type);
        return -EBUSY;
    }

    if (V4L2_TYPE_IS_OUTPUT(f->type))
        frame = &ctx->s_frame;
    else
        frame = &ctx->d_frame;

    pix = &f->fmt.pix_mp;
    frame->fmt = find_fmt(&pix->pixelformat, NULL, 0);
    frame->colorspace = pix->colorspace;
    if (!frame->fmt)
        return -EINVAL;

    for (i = 0; i < frame->fmt->num_planes; i++)
        frame->payload[i] = pix->plane_fmt[i].sizeimage;

    gsc_set_frame_size(frame, pix->width, pix->height);

    if (f->type == V4L2_BUF_TYPE_VIDEO_CAPTURE_MPLANE)
        gsc_ctx_state_lock_set(GSC_PARAMS | GSC_DST_FMT, ctx);
    else
        gsc_ctx_state_lock_set(GSC_PARAMS | GSC_SRC_FMT, ctx);

    pr_debug("f_w: %d, f_h: %d", frame->f_width, frame->f_height);

    return 0;
}

static int gsc_m2m_reqbufs(struct file *file, void *fh,
              struct v4l2_requestbuffers *reqbufs)
{
    struct gsc_ctx *ctx = fh_to_ctx(fh);
    struct gsc_dev *gsc = ctx->gsc_dev;
    struct gsc_frame *frame;
    u32 max_cnt;

    max_cnt = (reqbufs->type == V4L2_BUF_TYPE_VIDEO_OUTPUT_MPLANE) ?
        gsc->variant->in_buf_cnt : gsc->variant->out_buf_cnt;
    if (reqbufs->count > max_cnt) {
        return -EINVAL;
    } else if (reqbufs->count == 0) {
        if (reqbufs->type == V4L2_BUF_TYPE_VIDEO_OUTPUT_MPLANE)
            gsc_ctx_state_lock_clear(GSC_SRC_FMT, ctx);
        else
            gsc_ctx_state_lock_clear(GSC_DST_FMT, ctx);
    }

    frame = ctx_get_frame(ctx, reqbufs->type);

    return v4l2_m2m_reqbufs(file, ctx->m2m_ctx, reqbufs);
}

static int gsc_m2m_querybuf(struct file *file, void *fh,
                    struct v4l2_buffer *buf)
{
    struct gsc_ctx *ctx = fh_to_ctx(fh);
    return v4l2_m2m_querybuf(file, ctx->m2m_ctx, buf);
}

static int gsc_m2m_qbuf(struct file *file, void *fh,
              struct v4l2_buffer *buf)
{
    struct gsc_ctx *ctx = fh_to_ctx(fh);
    return v4l2_m2m_qbuf(file, ctx->m2m_ctx, buf);
}

static int gsc_m2m_dqbuf(struct file *file, void *fh,
               struct v4l2_buffer *buf)
{
    struct gsc_ctx *ctx = fh_to_ctx(fh);
    return v4l2_m2m_dqbuf(file, ctx->m2m_ctx, buf);
}

static int gsc_m2m_streamon(struct file *file, void *fh,
               enum v4l2_buf_type type)
{
    struct gsc_ctx *ctx = fh_to_ctx(fh);

    /* The source and target color format need to be set */
    if (V4L2_TYPE_IS_OUTPUT(type)) {
        if (!gsc_ctx_state_is_set(GSC_SRC_FMT, ctx))
            return -EINVAL;
    } else if (!gsc_ctx_state_is_set(GSC_DST_FMT, ctx)) {
        return -EINVAL;
    }

    return v4l2_m2m_streamon(file, ctx->m2m_ctx, type);
}

static int gsc_m2m_streamoff(struct file *file, void *fh,
                enum v4l2_buf_type type)
{
    struct gsc_ctx *ctx = fh_to_ctx(fh);
    return v4l2_m2m_streamoff(file, ctx->m2m_ctx, type);
}

/* Return 1 if rectangle a is enclosed in rectangle b, or 0 otherwise. */
static int is_rectangle_enclosed(struct v4l2_rect *a, struct v4l2_rect *b)
{
    if (a->left < b->left || a->top < b->top)
        return 0;

    if (a->left + a->width > b->left + b->width)
        return 0;

    if (a->top + a->height > b->top + b->height)
        return 0;

    return 1;
}

static int gsc_m2m_g_selection(struct file *file, void *fh,
            struct v4l2_selection *s)
{
    struct gsc_frame *frame;
    struct gsc_ctx *ctx = fh_to_ctx(fh);

    if ((s->type != V4L2_BUF_TYPE_VIDEO_CAPTURE_MPLANE) &&
        (s->type != V4L2_BUF_TYPE_VIDEO_OUTPUT_MPLANE))
        return -EINVAL;

    frame = ctx_get_frame(ctx, s->type);
    if (IS_ERR(frame))
        return PTR_ERR(frame);

    switch (s->target) {
    case V4L2_SEL_TGT_COMPOSE_DEFAULT:
    case V4L2_SEL_TGT_COMPOSE_BOUNDS:
    case V4L2_SEL_TGT_CROP_BOUNDS:
    case V4L2_SEL_TGT_CROP_DEFAULT:
        s->r.left = 0;
        s->r.top = 0;
        s->r.width = frame->f_width;
        s->r.height = frame->f_height;
        return 0;

    case V4L2_SEL_TGT_COMPOSE:
    case V4L2_SEL_TGT_CROP:
        s->r.left = frame->crop.left;
        s->r.top = frame->crop.top;
        s->r.width = frame->crop.width;
        s->r.height = frame->crop.height;
        return 0;
    }

    return -EINVAL;
}

static int gsc_m2m_s_selection(struct file *file, void *fh,
                struct v4l2_selection *s)
{
    struct gsc_frame *frame;
    struct gsc_ctx *ctx = fh_to_ctx(fh);
    struct v4l2_crop cr;
    struct gsc_variant *variant = ctx->gsc_dev->variant;
    int ret;

    cr.type = s->type;
    cr.c = s->r;

    if ((s->type != V4L2_BUF_TYPE_VIDEO_CAPTURE_MPLANE) &&
        (s->type != V4L2_BUF_TYPE_VIDEO_OUTPUT_MPLANE))
        return -EINVAL;

    ret = gsc_try_crop(ctx, &cr);
    if (ret)
        return ret;

    if (s->flags & V4L2_SEL_FLAG_LE &&
        !is_rectangle_enclosed(&cr.c, &s->r))
        return -ERANGE;

    if (s->flags & V4L2_SEL_FLAG_GE &&
        !is_rectangle_enclosed(&s->r, &cr.c))
        return -ERANGE;

    s->r = cr.c;

    switch (s->target) {
    case V4L2_SEL_TGT_COMPOSE_BOUNDS:
    case V4L2_SEL_TGT_COMPOSE_DEFAULT:
    case V4L2_SEL_TGT_COMPOSE:
        frame = &ctx->s_frame;
        break;

    case V4L2_SEL_TGT_CROP_BOUNDS:
    case V4L2_SEL_TGT_CROP:
    case V4L2_SEL_TGT_CROP_DEFAULT:
        frame = &ctx->d_frame;
        break;

    default:
        return -EINVAL;
    }

    /* Check to see if scaling ratio is within supported range */
    if (gsc_ctx_state_is_set(GSC_DST_FMT | GSC_SRC_FMT, ctx)) {
        if (s->type == V4L2_BUF_TYPE_VIDEO_OUTPUT_MPLANE) {
            ret = gsc_check_scaler_ratio(variant, cr.c.width,
                cr.c.height, ctx->d_frame.crop.width,
                ctx->d_frame.crop.height,
                ctx->gsc_ctrls.rotate->val, ctx->out_path);
        } else {
            ret = gsc_check_scaler_ratio(variant,
                ctx->s_frame.crop.width,
                ctx->s_frame.crop.height, cr.c.width,
                cr.c.height, ctx->gsc_ctrls.rotate->val,
                ctx->out_path);
        }

        if (ret) {
            pr_err("Out of scaler range");
            return -EINVAL;
        }
    }

    frame->crop = cr.c;

    gsc_ctx_state_lock_set(GSC_PARAMS, ctx);
    return 0;
}

static const struct v4l2_ioctl_ops gsc_m2m_ioctl_ops = {
    .vidioc_querycap        = gsc_m2m_querycap,
    .vidioc_enum_fmt_vid_cap_mplane = gsc_m2m_enum_fmt_mplane,
    .vidioc_enum_fmt_vid_out_mplane = gsc_m2m_enum_fmt_mplane,
    .vidioc_g_fmt_vid_cap_mplane    = gsc_m2m_g_fmt_mplane,
    .vidioc_g_fmt_vid_out_mplane    = gsc_m2m_g_fmt_mplane,
    .vidioc_try_fmt_vid_cap_mplane  = gsc_m2m_try_fmt_mplane,
    .vidioc_try_fmt_vid_out_mplane  = gsc_m2m_try_fmt_mplane,
    .vidioc_s_fmt_vid_cap_mplane    = gsc_m2m_s_fmt_mplane,
    .vidioc_s_fmt_vid_out_mplane    = gsc_m2m_s_fmt_mplane,
    .vidioc_reqbufs         = gsc_m2m_reqbufs,
    .vidioc_querybuf        = gsc_m2m_querybuf,
    .vidioc_qbuf            = gsc_m2m_qbuf,
    .vidioc_dqbuf           = gsc_m2m_dqbuf,
    .vidioc_streamon        = gsc_m2m_streamon,
    .vidioc_streamoff       = gsc_m2m_streamoff,
    .vidioc_g_selection     = gsc_m2m_g_selection,
    .vidioc_s_selection     = gsc_m2m_s_selection
};

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

    memset(src_vq, 0, sizeof(*src_vq));
    src_vq->type = V4L2_BUF_TYPE_VIDEO_OUTPUT_MPLANE;
    src_vq->io_modes = VB2_MMAP | VB2_USERPTR;
    src_vq->drv_priv = ctx;
    src_vq->ops = &gsc_m2m_qops;
    src_vq->mem_ops = &vb2_dma_contig_memops;
    src_vq->buf_struct_size = sizeof(struct v4l2_m2m_buffer);

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

    memset(dst_vq, 0, sizeof(*dst_vq));
    dst_vq->type = V4L2_BUF_TYPE_VIDEO_CAPTURE_MPLANE;
    dst_vq->io_modes = VB2_MMAP | VB2_USERPTR;
    dst_vq->drv_priv = ctx;
    dst_vq->ops = &gsc_m2m_qops;
    dst_vq->mem_ops = &vb2_dma_contig_memops;
    dst_vq->buf_struct_size = sizeof(struct v4l2_m2m_buffer);

    return vb2_queue_init(dst_vq);
}

static int gsc_m2m_open(struct file *file)
{
    struct gsc_dev *gsc = video_drvdata(file);
    struct gsc_ctx *ctx = NULL;
    int ret;

    pr_debug("pid: %d, state: 0x%lx", task_pid_nr(current), gsc->state);

    if (mutex_lock_interruptible(&gsc->lock))
        return -ERESTARTSYS;

    ctx = kzalloc(sizeof (*ctx), GFP_KERNEL);
    if (!ctx) {
        ret = -ENOMEM;
        goto unlock;
    }

    v4l2_fh_init(&ctx->fh, gsc->m2m.vfd);
    ret = gsc_ctrls_create(ctx);
    if (ret)
        goto error_fh;

    /* Use separate control handler per file handle */
    ctx->fh.ctrl_handler = &ctx->ctrl_handler;
    file->private_data = &ctx->fh;
    v4l2_fh_add(&ctx->fh);

    ctx->gsc_dev = gsc;
    /* Default color format */
    ctx->s_frame.fmt = get_format(0);
    ctx->d_frame.fmt = get_format(0);
    /* Setup the device context for mem2mem mode. */
    ctx->state = GSC_CTX_M2M;
    ctx->flags = 0;
    ctx->in_path = GSC_DMA;
    ctx->out_path = GSC_DMA;

    ctx->m2m_ctx = v4l2_m2m_ctx_init(gsc->m2m.m2m_dev, ctx, queue_init);
    if (IS_ERR(ctx->m2m_ctx)) {
        pr_err("Failed to initialize m2m context");
        ret = PTR_ERR(ctx->m2m_ctx);
        goto error_ctrls;
    }

    if (gsc->m2m.refcnt++ == 0)
        set_bit(ST_M2M_OPEN, &gsc->state);

    pr_debug("gsc m2m driver is opened, ctx(0x%p)", ctx);

    mutex_unlock(&gsc->lock);
    return 0;

error_ctrls:
    gsc_ctrls_delete(ctx);
error_fh:
    v4l2_fh_del(&ctx->fh);
    v4l2_fh_exit(&ctx->fh);
    kfree(ctx);
unlock:
    mutex_unlock(&gsc->lock);
    return ret;
}

static int gsc_m2m_release(struct file *file)
{
    struct gsc_ctx *ctx = fh_to_ctx(file->private_data);
    struct gsc_dev *gsc = ctx->gsc_dev;

    pr_debug("pid: %d, state: 0x%lx, refcnt= %d",
        task_pid_nr(current), gsc->state, gsc->m2m.refcnt);

    mutex_lock(&gsc->lock);

    v4l2_m2m_ctx_release(ctx->m2m_ctx);
    gsc_ctrls_delete(ctx);
    v4l2_fh_del(&ctx->fh);
    v4l2_fh_exit(&ctx->fh);

    if (--gsc->m2m.refcnt <= 0)
        clear_bit(ST_M2M_OPEN, &gsc->state);
    kfree(ctx);

    mutex_unlock(&gsc->lock);
    return 0;
}

static unsigned int gsc_m2m_poll(struct file *file,
                    struct poll_table_struct *wait)
{
    struct gsc_ctx *ctx = fh_to_ctx(file->private_data);
    struct gsc_dev *gsc = ctx->gsc_dev;
    int ret;

    if (mutex_lock_interruptible(&gsc->lock))
        return -ERESTARTSYS;

    ret = v4l2_m2m_poll(file, ctx->m2m_ctx, wait);
    mutex_unlock(&gsc->lock);

    return ret;
}

static int gsc_m2m_mmap(struct file *file, struct vm_area_struct *vma)
{
    struct gsc_ctx *ctx = fh_to_ctx(file->private_data);
    struct gsc_dev *gsc = ctx->gsc_dev;
    int ret;

    if (mutex_lock_interruptible(&gsc->lock))
        return -ERESTARTSYS;

    ret = v4l2_m2m_mmap(file, ctx->m2m_ctx, vma);
    mutex_unlock(&gsc->lock);

    return ret;
}

static const struct v4l2_file_operations gsc_m2m_fops = {
    .owner      = THIS_MODULE,
    .open       = gsc_m2m_open,
    .release    = gsc_m2m_release,
    .poll       = gsc_m2m_poll,
    .unlocked_ioctl = video_ioctl2,
    .mmap       = gsc_m2m_mmap,
};

static struct v4l2_m2m_ops gsc_m2m_ops = {
    .device_run = gsc_m2m_device_run,
    .job_abort  = gsc_m2m_job_abort,
};

int gsc_register_m2m_device(struct gsc_dev *gsc)
{
    struct platform_device *pdev;
    int ret;

    if (!gsc)
        return -ENODEV;

    pdev = gsc->pdev;

    gsc->vdev.fops      = &gsc_m2m_fops;
    gsc->vdev.ioctl_ops = &gsc_m2m_ioctl_ops;
    gsc->vdev.release   = video_device_release_empty;
    gsc->vdev.lock      = &gsc->lock;
    gsc->vdev.vfl_dir   = VFL_DIR_M2M;
    snprintf(gsc->vdev.name, sizeof(gsc->vdev.name), "%s.%d:m2m",
                    GSC_MODULE_NAME, gsc->id);

    video_set_drvdata(&gsc->vdev, gsc);

    gsc->m2m.vfd = &gsc->vdev;
    gsc->m2m.m2m_dev = v4l2_m2m_init(&gsc_m2m_ops);
    if (IS_ERR(gsc->m2m.m2m_dev)) {
        dev_err(&pdev->dev, "failed to initialize v4l2-m2m device\n");
        ret = PTR_ERR(gsc->m2m.m2m_dev);
        goto err_m2m_r1;
    }

    ret = video_register_device(&gsc->vdev, VFL_TYPE_GRABBER, -1);
    if (ret) {
        dev_err(&pdev->dev,
             "%s(): failed to register video device\n", __func__);
        goto err_m2m_r2;
    }

    pr_debug("gsc m2m driver registered as /dev/video%d", gsc->vdev.num);
    return 0;

err_m2m_r2:
    v4l2_m2m_release(gsc->m2m.m2m_dev);
err_m2m_r1:
    video_device_release(gsc->m2m.vfd);

    return ret;
}

void gsc_unregister_m2m_device(struct gsc_dev *gsc)
{
    if (gsc)
        v4l2_m2m_release(gsc->m2m.m2m_dev);
}