Merge branch 'perf-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel...

[cris-mirror.git] / drivers / media / v4l2-core / videobuf2-v4l2.c

/*
 * videobuf2-v4l2.c - V4L2 driver helper framework
 *
 * Copyright (C) 2010 Samsung Electronics
 *
 * Author: Pawel Osciak <pawel@osciak.com>
 *         Marek Szyprowski <m.szyprowski@samsung.com>
 *
 * The vb2_thread implementation was based on code from videobuf-dvb.c:
 *      (c) 2004 Gerd Knorr <kraxel@bytesex.org> [SUSE Labs]
 *
 * 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.
 */

#include <linux/err.h>
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/mm.h>
#include <linux/poll.h>
#include <linux/slab.h>
#include <linux/sched.h>
#include <linux/freezer.h>
#include <linux/kthread.h>

#include <media/v4l2-dev.h>
#include <media/v4l2-fh.h>
#include <media/v4l2-event.h>
#include <media/v4l2-common.h>

#include <media/videobuf2-v4l2.h>

static int debug;
module_param(debug, int, 0644);

#define dprintk(level, fmt, arg...)                                           \
        do {                                                                  \
                if (debug >= level)                                           \
                        pr_info("vb2-v4l2: %s: " fmt, __func__, ## arg); \
        } while (0)

/* Flags that are set by the vb2 core */
#define V4L2_BUFFER_MASK_FLAGS  (V4L2_BUF_FLAG_MAPPED | V4L2_BUF_FLAG_QUEUED | \
                                 V4L2_BUF_FLAG_DONE | V4L2_BUF_FLAG_ERROR | \
                                 V4L2_BUF_FLAG_PREPARED | \
                                 V4L2_BUF_FLAG_TIMESTAMP_MASK)
/* Output buffer flags that should be passed on to the driver */
#define V4L2_BUFFER_OUT_FLAGS   (V4L2_BUF_FLAG_PFRAME | V4L2_BUF_FLAG_BFRAME | \
                                 V4L2_BUF_FLAG_KEYFRAME | V4L2_BUF_FLAG_TIMECODE)

/**
 * __verify_planes_array() - verify that the planes array passed in struct
 * v4l2_buffer from userspace can be safely used
 */
static int __verify_planes_array(struct vb2_buffer *vb, const struct v4l2_buffer *b)
{
        if (!V4L2_TYPE_IS_MULTIPLANAR(b->type))
                return 0;

        /* Is memory for copying plane information present? */
        if (b->m.planes == NULL) {
                dprintk(1, "multi-planar buffer passed but "
                           "planes array not provided\n");
                return -EINVAL;
        }

        if (b->length < vb->num_planes || b->length > VB2_MAX_PLANES) {
                dprintk(1, "incorrect planes array length, "
                           "expected %d, got %d\n", vb->num_planes, b->length);
                return -EINVAL;
        }

        return 0;
}

static int __verify_planes_array_core(struct vb2_buffer *vb, const void *pb)
{
        return __verify_planes_array(vb, pb);
}

/**
 * __verify_length() - Verify that the bytesused value for each plane fits in
 * the plane length and that the data offset doesn't exceed the bytesused value.
 */
static int __verify_length(struct vb2_buffer *vb, const struct v4l2_buffer *b)
{
        unsigned int length;
        unsigned int bytesused;
        unsigned int plane;

        if (!V4L2_TYPE_IS_OUTPUT(b->type))
                return 0;

        if (V4L2_TYPE_IS_MULTIPLANAR(b->type)) {
                for (plane = 0; plane < vb->num_planes; ++plane) {
                        length = (b->memory == VB2_MEMORY_USERPTR ||
                                  b->memory == VB2_MEMORY_DMABUF)
                               ? b->m.planes[plane].length
                                : vb->planes[plane].length;
                        bytesused = b->m.planes[plane].bytesused
                                  ? b->m.planes[plane].bytesused : length;

                        if (b->m.planes[plane].bytesused > length)
                                return -EINVAL;

                        if (b->m.planes[plane].data_offset > 0 &&
                            b->m.planes[plane].data_offset >= bytesused)
                                return -EINVAL;
                }
        } else {
                length = (b->memory == VB2_MEMORY_USERPTR)
                        ? b->length : vb->planes[0].length;

                if (b->bytesused > length)
                        return -EINVAL;
        }

        return 0;
}

static void __copy_timestamp(struct vb2_buffer *vb, const void *pb)
{
        const struct v4l2_buffer *b = pb;
        struct vb2_v4l2_buffer *vbuf = to_vb2_v4l2_buffer(vb);
        struct vb2_queue *q = vb->vb2_queue;

        if (q->is_output) {
                /*
                 * For output buffers copy the timestamp if needed,
                 * and the timecode field and flag if needed.
                 */
                if (q->copy_timestamp)
                        vb->timestamp = timeval_to_ns(&b->timestamp);
                vbuf->flags |= b->flags & V4L2_BUF_FLAG_TIMECODE;
                if (b->flags & V4L2_BUF_FLAG_TIMECODE)
                        vbuf->timecode = b->timecode;
        }
};

static void vb2_warn_zero_bytesused(struct vb2_buffer *vb)
{
        static bool check_once;

        if (check_once)
                return;

        check_once = true;
        WARN_ON(1);

        pr_warn("use of bytesused == 0 is deprecated and will be removed in the future,\n");
        if (vb->vb2_queue->allow_zero_bytesused)
                pr_warn("use VIDIOC_DECODER_CMD(V4L2_DEC_CMD_STOP) instead.\n");
        else
                pr_warn("use the actual size instead.\n");
}

static int vb2_queue_or_prepare_buf(struct vb2_queue *q, struct v4l2_buffer *b,
                                    const char *opname)
{
        if (b->type != q->type) {
                dprintk(1, "%s: invalid buffer type\n", opname);
                return -EINVAL;
        }

        if (b->index >= q->num_buffers) {
                dprintk(1, "%s: buffer index out of range\n", opname);
                return -EINVAL;
        }

        if (q->bufs[b->index] == NULL) {
                /* Should never happen */
                dprintk(1, "%s: buffer is NULL\n", opname);
                return -EINVAL;
        }

        if (b->memory != q->memory) {
                dprintk(1, "%s: invalid memory type\n", opname);
                return -EINVAL;
        }

        return __verify_planes_array(q->bufs[b->index], b);
}

/**
 * __fill_v4l2_buffer() - fill in a struct v4l2_buffer with information to be
 * returned to userspace
 */
static void __fill_v4l2_buffer(struct vb2_buffer *vb, void *pb)
{
        struct v4l2_buffer *b = pb;
        struct vb2_v4l2_buffer *vbuf = to_vb2_v4l2_buffer(vb);
        struct vb2_queue *q = vb->vb2_queue;
        unsigned int plane;

        /* Copy back data such as timestamp, flags, etc. */
        b->index = vb->index;
        b->type = vb->type;
        b->memory = vb->memory;
        b->bytesused = 0;

        b->flags = vbuf->flags;
        b->field = vbuf->field;
        b->timestamp = ns_to_timeval(vb->timestamp);
        b->timecode = vbuf->timecode;
        b->sequence = vbuf->sequence;
        b->reserved2 = 0;
        b->reserved = 0;

        if (q->is_multiplanar) {
                /*
                 * Fill in plane-related data if userspace provided an array
                 * for it. The caller has already verified memory and size.
                 */
                b->length = vb->num_planes;
                for (plane = 0; plane < vb->num_planes; ++plane) {
                        struct v4l2_plane *pdst = &b->m.planes[plane];
                        struct vb2_plane *psrc = &vb->planes[plane];

                        pdst->bytesused = psrc->bytesused;
                        pdst->length = psrc->length;
                        if (q->memory == VB2_MEMORY_MMAP)
                                pdst->m.mem_offset = psrc->m.offset;
                        else if (q->memory == VB2_MEMORY_USERPTR)
                                pdst->m.userptr = psrc->m.userptr;
                        else if (q->memory == VB2_MEMORY_DMABUF)
                                pdst->m.fd = psrc->m.fd;
                        pdst->data_offset = psrc->data_offset;
                        memset(pdst->reserved, 0, sizeof(pdst->reserved));
                }
        } else {
                /*
                 * We use length and offset in v4l2_planes array even for
                 * single-planar buffers, but userspace does not.
                 */
                b->length = vb->planes[0].length;
                b->bytesused = vb->planes[0].bytesused;
                if (q->memory == VB2_MEMORY_MMAP)
                        b->m.offset = vb->planes[0].m.offset;
                else if (q->memory == VB2_MEMORY_USERPTR)
                        b->m.userptr = vb->planes[0].m.userptr;
                else if (q->memory == VB2_MEMORY_DMABUF)
                        b->m.fd = vb->planes[0].m.fd;
        }

        /*
         * Clear any buffer state related flags.
         */
        b->flags &= ~V4L2_BUFFER_MASK_FLAGS;
        b->flags |= q->timestamp_flags & V4L2_BUF_FLAG_TIMESTAMP_MASK;
        if (!q->copy_timestamp) {
                /*
                 * For non-COPY timestamps, drop timestamp source bits
                 * and obtain the timestamp source from the queue.
                 */
                b->flags &= ~V4L2_BUF_FLAG_TSTAMP_SRC_MASK;
                b->flags |= q->timestamp_flags & V4L2_BUF_FLAG_TSTAMP_SRC_MASK;
        }

        switch (vb->state) {
        case VB2_BUF_STATE_QUEUED:
        case VB2_BUF_STATE_ACTIVE:
                b->flags |= V4L2_BUF_FLAG_QUEUED;
                break;
        case VB2_BUF_STATE_ERROR:
                b->flags |= V4L2_BUF_FLAG_ERROR;
                /* fall through */
        case VB2_BUF_STATE_DONE:
                b->flags |= V4L2_BUF_FLAG_DONE;
                break;
        case VB2_BUF_STATE_PREPARED:
                b->flags |= V4L2_BUF_FLAG_PREPARED;
                break;
        case VB2_BUF_STATE_PREPARING:
        case VB2_BUF_STATE_DEQUEUED:
        case VB2_BUF_STATE_REQUEUEING:
                /* nothing */
                break;
        }

        if (vb2_buffer_in_use(q, vb))
                b->flags |= V4L2_BUF_FLAG_MAPPED;

        if (!q->is_output &&
                b->flags & V4L2_BUF_FLAG_DONE &&
                b->flags & V4L2_BUF_FLAG_LAST)
                q->last_buffer_dequeued = true;
}

/**
 * __fill_vb2_buffer() - fill a vb2_buffer with information provided in a
 * v4l2_buffer by the userspace. It also verifies that struct
 * v4l2_buffer has a valid number of planes.
 */
static int __fill_vb2_buffer(struct vb2_buffer *vb,
                const void *pb, struct vb2_plane *planes)
{
        struct vb2_queue *q = vb->vb2_queue;
        const struct v4l2_buffer *b = pb;
        struct vb2_v4l2_buffer *vbuf = to_vb2_v4l2_buffer(vb);
        unsigned int plane;
        int ret;

        ret = __verify_length(vb, b);
        if (ret < 0) {
                dprintk(1, "plane parameters verification failed: %d\n", ret);
                return ret;
        }
        if (b->field == V4L2_FIELD_ALTERNATE && q->is_output) {
                /*
                 * If the format's field is ALTERNATE, then the buffer's field
                 * should be either TOP or BOTTOM, not ALTERNATE since that
                 * makes no sense. The driver has to know whether the
                 * buffer represents a top or a bottom field in order to
                 * program any DMA correctly. Using ALTERNATE is wrong, since
                 * that just says that it is either a top or a bottom field,
                 * but not which of the two it is.
                 */
                dprintk(1, "the field is incorrectly set to ALTERNATE "
                                        "for an output buffer\n");
                return -EINVAL;
        }
        vb->timestamp = 0;
        vbuf->sequence = 0;

        if (V4L2_TYPE_IS_MULTIPLANAR(b->type)) {
                if (b->memory == VB2_MEMORY_USERPTR) {
                        for (plane = 0; plane < vb->num_planes; ++plane) {
                                planes[plane].m.userptr =
                                        b->m.planes[plane].m.userptr;
                                planes[plane].length =
                                        b->m.planes[plane].length;
                        }
                }
                if (b->memory == VB2_MEMORY_DMABUF) {
                        for (plane = 0; plane < vb->num_planes; ++plane) {
                                planes[plane].m.fd =
                                        b->m.planes[plane].m.fd;
                                planes[plane].length =
                                        b->m.planes[plane].length;
                        }
                }

                /* Fill in driver-provided information for OUTPUT types */
                if (V4L2_TYPE_IS_OUTPUT(b->type)) {
                        /*
                         * Will have to go up to b->length when API starts
                         * accepting variable number of planes.
                         *
                         * If bytesused == 0 for the output buffer, then fall
                         * back to the full buffer size. In that case
                         * userspace clearly never bothered to set it and
                         * it's a safe assumption that they really meant to
                         * use the full plane sizes.
                         *
                         * Some drivers, e.g. old codec drivers, use bytesused == 0
                         * as a way to indicate that streaming is finished.
                         * In that case, the driver should use the
                         * allow_zero_bytesused flag to keep old userspace
                         * applications working.
                         */
                        for (plane = 0; plane < vb->num_planes; ++plane) {
                                struct vb2_plane *pdst = &planes[plane];
                                struct v4l2_plane *psrc = &b->m.planes[plane];

                                if (psrc->bytesused == 0)
                                        vb2_warn_zero_bytesused(vb);

                                if (vb->vb2_queue->allow_zero_bytesused)
                                        pdst->bytesused = psrc->bytesused;
                                else
                                        pdst->bytesused = psrc->bytesused ?
                                                psrc->bytesused : pdst->length;
                                pdst->data_offset = psrc->data_offset;
                        }
                }
        } else {
                /*
                 * Single-planar buffers do not use planes array,
                 * so fill in relevant v4l2_buffer struct fields instead.
                 * In videobuf we use our internal V4l2_planes struct for
                 * single-planar buffers as well, for simplicity.
                 *
                 * If bytesused == 0 for the output buffer, then fall back
                 * to the full buffer size as that's a sensible default.
                 *
                 * Some drivers, e.g. old codec drivers, use bytesused == 0 as
                 * a way to indicate that streaming is finished. In that case,
                 * the driver should use the allow_zero_bytesused flag to keep
                 * old userspace applications working.
                 */
                if (b->memory == VB2_MEMORY_USERPTR) {
                        planes[0].m.userptr = b->m.userptr;
                        planes[0].length = b->length;
                }

                if (b->memory == VB2_MEMORY_DMABUF) {
                        planes[0].m.fd = b->m.fd;
                        planes[0].length = b->length;
                }

                if (V4L2_TYPE_IS_OUTPUT(b->type)) {
                        if (b->bytesused == 0)
                                vb2_warn_zero_bytesused(vb);

                        if (vb->vb2_queue->allow_zero_bytesused)
                                planes[0].bytesused = b->bytesused;
                        else
                                planes[0].bytesused = b->bytesused ?
                                        b->bytesused : planes[0].length;
                } else
                        planes[0].bytesused = 0;

        }

        /* Zero flags that the vb2 core handles */
        vbuf->flags = b->flags & ~V4L2_BUFFER_MASK_FLAGS;
        if (!vb->vb2_queue->copy_timestamp || !V4L2_TYPE_IS_OUTPUT(b->type)) {
                /*
                 * Non-COPY timestamps and non-OUTPUT queues will get
                 * their timestamp and timestamp source flags from the
                 * queue.
                 */
                vbuf->flags &= ~V4L2_BUF_FLAG_TSTAMP_SRC_MASK;
        }

        if (V4L2_TYPE_IS_OUTPUT(b->type)) {
                /*
                 * For output buffers mask out the timecode flag:
                 * this will be handled later in vb2_qbuf().
                 * The 'field' is valid metadata for this output buffer
                 * and so that needs to be copied here.
                 */
                vbuf->flags &= ~V4L2_BUF_FLAG_TIMECODE;
                vbuf->field = b->field;
        } else {
                /* Zero any output buffer flags as this is a capture buffer */
                vbuf->flags &= ~V4L2_BUFFER_OUT_FLAGS;
        }

        return 0;
}

static const struct vb2_buf_ops v4l2_buf_ops = {
        .verify_planes_array    = __verify_planes_array_core,
        .fill_user_buffer       = __fill_v4l2_buffer,
        .fill_vb2_buffer        = __fill_vb2_buffer,
        .copy_timestamp         = __copy_timestamp,
};

/**
 * vb2_querybuf() - query video buffer information
 * @q:          videobuf queue
 * @b:          buffer struct passed from userspace to vidioc_querybuf handler
 *              in driver
 *
 * Should be called from vidioc_querybuf ioctl handler in driver.
 * This function will verify the passed v4l2_buffer structure and fill the
 * relevant information for the userspace.
 *
 * The return values from this function are intended to be directly returned
 * from vidioc_querybuf handler in driver.
 */
int vb2_querybuf(struct vb2_queue *q, struct v4l2_buffer *b)
{
        struct vb2_buffer *vb;
        int ret;

        if (b->type != q->type) {
                dprintk(1, "wrong buffer type\n");
                return -EINVAL;
        }

        if (b->index >= q->num_buffers) {
                dprintk(1, "buffer index out of range\n");
                return -EINVAL;
        }
        vb = q->bufs[b->index];
        ret = __verify_planes_array(vb, b);
        if (!ret)
                vb2_core_querybuf(q, b->index, b);
        return ret;
}
EXPORT_SYMBOL(vb2_querybuf);

/**
 * vb2_reqbufs() - Wrapper for vb2_core_reqbufs() that also verifies
 * the memory and type values.
 * @q:          videobuf2 queue
 * @req:        struct passed from userspace to vidioc_reqbufs handler
 *              in driver
 */
int vb2_reqbufs(struct vb2_queue *q, struct v4l2_requestbuffers *req)
{
        int ret = vb2_verify_memory_type(q, req->memory, req->type);

        return ret ? ret : vb2_core_reqbufs(q, req->memory, &req->count);
}
EXPORT_SYMBOL_GPL(vb2_reqbufs);

/**
 * vb2_prepare_buf() - Pass ownership of a buffer from userspace to the kernel
 * @q:          videobuf2 queue
 * @b:          buffer structure passed from userspace to vidioc_prepare_buf
 *              handler in driver
 *
 * Should be called from vidioc_prepare_buf ioctl handler of a driver.
 * This function:
 * 1) verifies the passed buffer,
 * 2) calls buf_prepare callback in the driver (if provided), in which
 *    driver-specific buffer initialization can be performed,
 *
 * The return values from this function are intended to be directly returned
 * from vidioc_prepare_buf handler in driver.
 */
int vb2_prepare_buf(struct vb2_queue *q, struct v4l2_buffer *b)
{
        int ret;

        if (vb2_fileio_is_active(q)) {
                dprintk(1, "file io in progress\n");
                return -EBUSY;
        }

        ret = vb2_queue_or_prepare_buf(q, b, "prepare_buf");

        return ret ? ret : vb2_core_prepare_buf(q, b->index, b);
}
EXPORT_SYMBOL_GPL(vb2_prepare_buf);

/**
 * vb2_create_bufs() - Wrapper for vb2_core_create_bufs() that also verifies
 * the memory and type values.
 * @q:          videobuf2 queue
 * @create:     creation parameters, passed from userspace to vidioc_create_bufs
 *              handler in driver
 */
int vb2_create_bufs(struct vb2_queue *q, struct v4l2_create_buffers *create)
{
        unsigned requested_planes = 1;
        unsigned requested_sizes[VIDEO_MAX_PLANES];
        struct v4l2_format *f = &create->format;
        int ret = vb2_verify_memory_type(q, create->memory, f->type);
        unsigned i;

        create->index = q->num_buffers;
        if (create->count == 0)
                return ret != -EBUSY ? ret : 0;

        switch (f->type) {
        case V4L2_BUF_TYPE_VIDEO_CAPTURE_MPLANE:
        case V4L2_BUF_TYPE_VIDEO_OUTPUT_MPLANE:
                requested_planes = f->fmt.pix_mp.num_planes;
                if (requested_planes == 0 ||
                    requested_planes > VIDEO_MAX_PLANES)
                        return -EINVAL;
                for (i = 0; i < requested_planes; i++)
                        requested_sizes[i] =
                                f->fmt.pix_mp.plane_fmt[i].sizeimage;
                break;
        case V4L2_BUF_TYPE_VIDEO_CAPTURE:
        case V4L2_BUF_TYPE_VIDEO_OUTPUT:
                requested_sizes[0] = f->fmt.pix.sizeimage;
                break;
        case V4L2_BUF_TYPE_VBI_CAPTURE:
        case V4L2_BUF_TYPE_VBI_OUTPUT:
                requested_sizes[0] = f->fmt.vbi.samples_per_line *
                        (f->fmt.vbi.count[0] + f->fmt.vbi.count[1]);
                break;
        case V4L2_BUF_TYPE_SLICED_VBI_CAPTURE:
        case V4L2_BUF_TYPE_SLICED_VBI_OUTPUT:
                requested_sizes[0] = f->fmt.sliced.io_size;
                break;
        case V4L2_BUF_TYPE_SDR_CAPTURE:
        case V4L2_BUF_TYPE_SDR_OUTPUT:
                requested_sizes[0] = f->fmt.sdr.buffersize;
                break;
        default:
                return -EINVAL;
        }
        for (i = 0; i < requested_planes; i++)
                if (requested_sizes[i] == 0)
                        return -EINVAL;
        return ret ? ret : vb2_core_create_bufs(q, create->memory,
                &create->count, requested_planes, requested_sizes);
}
EXPORT_SYMBOL_GPL(vb2_create_bufs);

/**
 * vb2_qbuf() - Queue a buffer from userspace
 * @q:          videobuf2 queue
 * @b:          buffer structure passed from userspace to vidioc_qbuf handler
 *              in driver
 *
 * Should be called from vidioc_qbuf ioctl handler of a driver.
 * This function:
 * 1) verifies the passed buffer,
 * 2) if necessary, calls buf_prepare callback in the driver (if provided), in
 *    which driver-specific buffer initialization can be performed,
 * 3) if streaming is on, queues the buffer in driver by the means of buf_queue
 *    callback for processing.
 *
 * The return values from this function are intended to be directly returned
 * from vidioc_qbuf handler in driver.
 */
int vb2_qbuf(struct vb2_queue *q, struct v4l2_buffer *b)
{
        int ret;

        if (vb2_fileio_is_active(q)) {
                dprintk(1, "file io in progress\n");
                return -EBUSY;
        }

        ret = vb2_queue_or_prepare_buf(q, b, "qbuf");
        return ret ? ret : vb2_core_qbuf(q, b->index, b);
}
EXPORT_SYMBOL_GPL(vb2_qbuf);

/**
 * vb2_dqbuf() - Dequeue a buffer to the userspace
 * @q:          videobuf2 queue
 * @b:          buffer structure passed from userspace to vidioc_dqbuf handler
 *              in driver
 * @nonblocking: if true, this call will not sleep waiting for a buffer if no
 *               buffers ready for dequeuing are present. Normally the driver
 *               would be passing (file->f_flags & O_NONBLOCK) here
 *
 * Should be called from vidioc_dqbuf ioctl handler of a driver.
 * This function:
 * 1) verifies the passed buffer,
 * 2) calls buf_finish callback in the driver (if provided), in which
 *    driver can perform any additional operations that may be required before
 *    returning the buffer to userspace, such as cache sync,
 * 3) the buffer struct members are filled with relevant information for
 *    the userspace.
 *
 * The return values from this function are intended to be directly returned
 * from vidioc_dqbuf handler in driver.
 */
int vb2_dqbuf(struct vb2_queue *q, struct v4l2_buffer *b, bool nonblocking)
{
        int ret;

        if (vb2_fileio_is_active(q)) {
                dprintk(1, "file io in progress\n");
                return -EBUSY;
        }

        if (b->type != q->type) {
                dprintk(1, "invalid buffer type\n");
                return -EINVAL;
        }

        ret = vb2_core_dqbuf(q, NULL, b, nonblocking);

        /*
         *  After calling the VIDIOC_DQBUF V4L2_BUF_FLAG_DONE must be
         *  cleared.
         */
        b->flags &= ~V4L2_BUF_FLAG_DONE;

        return ret;
}
EXPORT_SYMBOL_GPL(vb2_dqbuf);

/**
 * vb2_streamon - start streaming
 * @q:          videobuf2 queue
 * @type:       type argument passed from userspace to vidioc_streamon handler
 *
 * Should be called from vidioc_streamon handler of a driver.
 * This function:
 * 1) verifies current state
 * 2) passes any previously queued buffers to the driver and starts streaming
 *
 * The return values from this function are intended to be directly returned
 * from vidioc_streamon handler in the driver.
 */
int vb2_streamon(struct vb2_queue *q, enum v4l2_buf_type type)
{
        if (vb2_fileio_is_active(q)) {
                dprintk(1, "file io in progress\n");
                return -EBUSY;
        }
        return vb2_core_streamon(q, type);
}
EXPORT_SYMBOL_GPL(vb2_streamon);

/**
 * vb2_streamoff - stop streaming
 * @q:          videobuf2 queue
 * @type:       type argument passed from userspace to vidioc_streamoff handler
 *
 * Should be called from vidioc_streamoff handler of a driver.
 * This function:
 * 1) verifies current state,
 * 2) stop streaming and dequeues any queued buffers, including those previously
 *    passed to the driver (after waiting for the driver to finish).
 *
 * This call can be used for pausing playback.
 * The return values from this function are intended to be directly returned
 * from vidioc_streamoff handler in the driver
 */
int vb2_streamoff(struct vb2_queue *q, enum v4l2_buf_type type)
{
        if (vb2_fileio_is_active(q)) {
                dprintk(1, "file io in progress\n");
                return -EBUSY;
        }
        return vb2_core_streamoff(q, type);
}
EXPORT_SYMBOL_GPL(vb2_streamoff);

/**
 * vb2_expbuf() - Export a buffer as a file descriptor
 * @q:          videobuf2 queue
 * @eb:         export buffer structure passed from userspace to vidioc_expbuf
 *              handler in driver
 *
 * The return values from this function are intended to be directly returned
 * from vidioc_expbuf handler in driver.
 */
int vb2_expbuf(struct vb2_queue *q, struct v4l2_exportbuffer *eb)
{
        return vb2_core_expbuf(q, &eb->fd, eb->type, eb->index,
                                eb->plane, eb->flags);
}
EXPORT_SYMBOL_GPL(vb2_expbuf);

/**
 * vb2_queue_init() - initialize a videobuf2 queue
 * @q:          videobuf2 queue; this structure should be allocated in driver
 *
 * The vb2_queue structure should be allocated by the driver. The driver is
 * responsible of clearing it's content and setting initial values for some
 * required entries before calling this function.
 * q->ops, q->mem_ops, q->type and q->io_modes are mandatory. Please refer
 * to the struct vb2_queue description in include/media/videobuf2-core.h
 * for more information.
 */
int vb2_queue_init(struct vb2_queue *q)
{
        /*
         * Sanity check
         */
        if (WARN_ON(!q)                   ||
            WARN_ON(q->timestamp_flags &
                    ~(V4L2_BUF_FLAG_TIMESTAMP_MASK |
                      V4L2_BUF_FLAG_TSTAMP_SRC_MASK)))
                return -EINVAL;

        /* Warn that the driver should choose an appropriate timestamp type */
        WARN_ON((q->timestamp_flags & V4L2_BUF_FLAG_TIMESTAMP_MASK) ==
                V4L2_BUF_FLAG_TIMESTAMP_UNKNOWN);

        /* Warn that vb2_memory should match with v4l2_memory */
        if (WARN_ON(VB2_MEMORY_MMAP != (int)V4L2_MEMORY_MMAP)
                || WARN_ON(VB2_MEMORY_USERPTR != (int)V4L2_MEMORY_USERPTR)
                || WARN_ON(VB2_MEMORY_DMABUF != (int)V4L2_MEMORY_DMABUF))
                return -EINVAL;

        if (q->buf_struct_size == 0)
                q->buf_struct_size = sizeof(struct vb2_v4l2_buffer);

        q->buf_ops = &v4l2_buf_ops;
        q->is_multiplanar = V4L2_TYPE_IS_MULTIPLANAR(q->type);
        q->is_output = V4L2_TYPE_IS_OUTPUT(q->type);
        q->copy_timestamp = (q->timestamp_flags & V4L2_BUF_FLAG_TIMESTAMP_MASK)
                        == V4L2_BUF_FLAG_TIMESTAMP_COPY;
        /*
         * For compatibility with vb1: if QBUF hasn't been called yet, then
         * return POLLERR as well. This only affects capture queues, output
         * queues will always initialize waiting_for_buffers to false.
         */
        q->quirk_poll_must_check_waiting_for_buffers = true;

        return vb2_core_queue_init(q);
}
EXPORT_SYMBOL_GPL(vb2_queue_init);

/**
 * vb2_queue_release() - stop streaming, release the queue and free memory
 * @q:          videobuf2 queue
 *
 * This function stops streaming and performs necessary clean ups, including
 * freeing video buffer memory. The driver is responsible for freeing
 * the vb2_queue structure itself.
 */
void vb2_queue_release(struct vb2_queue *q)
{
        vb2_core_queue_release(q);
}
EXPORT_SYMBOL_GPL(vb2_queue_release);

/**
 * vb2_poll() - implements poll userspace operation
 * @q:          videobuf2 queue
 * @file:       file argument passed to the poll file operation handler
 * @wait:       wait argument passed to the poll file operation handler
 *
 * This function implements poll file operation handler for a driver.
 * For CAPTURE queues, if a buffer is ready to be dequeued, the userspace will
 * be informed that the file descriptor of a video device is available for
 * reading.
 * For OUTPUT queues, if a buffer is ready to be dequeued, the file descriptor
 * will be reported as available for writing.
 *
 * If the driver uses struct v4l2_fh, then vb2_poll() will also check for any
 * pending events.
 *
 * The return values from this function are intended to be directly returned
 * from poll handler in driver.
 */
unsigned int vb2_poll(struct vb2_queue *q, struct file *file, poll_table *wait)
{
        struct video_device *vfd = video_devdata(file);
        unsigned long req_events = poll_requested_events(wait);
        unsigned int res = 0;

        if (test_bit(V4L2_FL_USES_V4L2_FH, &vfd->flags)) {
                struct v4l2_fh *fh = file->private_data;

                if (v4l2_event_pending(fh))
                        res = POLLPRI;
                else if (req_events & POLLPRI)
                        poll_wait(file, &fh->wait, wait);
        }

        return res | vb2_core_poll(q, file, wait);
}
EXPORT_SYMBOL_GPL(vb2_poll);

/*
 * The following functions are not part of the vb2 core API, but are helper
 * functions that plug into struct v4l2_ioctl_ops, struct v4l2_file_operations
 * and struct vb2_ops.
 * They contain boilerplate code that most if not all drivers have to do
 * and so they simplify the driver code.
 */

/* The queue is busy if there is a owner and you are not that owner. */
static inline bool vb2_queue_is_busy(struct video_device *vdev, struct file *file)
{
        return vdev->queue->owner && vdev->queue->owner != file->private_data;
}

/* vb2 ioctl helpers */

int vb2_ioctl_reqbufs(struct file *file, void *priv,
                          struct v4l2_requestbuffers *p)
{
        struct video_device *vdev = video_devdata(file);
        int res = vb2_verify_memory_type(vdev->queue, p->memory, p->type);

        if (res)
                return res;
        if (vb2_queue_is_busy(vdev, file))
                return -EBUSY;
        res = vb2_core_reqbufs(vdev->queue, p->memory, &p->count);
        /* If count == 0, then the owner has released all buffers and he
           is no longer owner of the queue. Otherwise we have a new owner. */
        if (res == 0)
                vdev->queue->owner = p->count ? file->private_data : NULL;
        return res;
}
EXPORT_SYMBOL_GPL(vb2_ioctl_reqbufs);

int vb2_ioctl_create_bufs(struct file *file, void *priv,
                          struct v4l2_create_buffers *p)
{
        struct video_device *vdev = video_devdata(file);
        int res = vb2_verify_memory_type(vdev->queue, p->memory,
                        p->format.type);

        p->index = vdev->queue->num_buffers;
        /*
         * If count == 0, then just check if memory and type are valid.
         * Any -EBUSY result from vb2_verify_memory_type can be mapped to 0.
         */
        if (p->count == 0)
                return res != -EBUSY ? res : 0;
        if (res)
                return res;
        if (vb2_queue_is_busy(vdev, file))
                return -EBUSY;

        res = vb2_create_bufs(vdev->queue, p);
        if (res == 0)
                vdev->queue->owner = file->private_data;
        return res;
}
EXPORT_SYMBOL_GPL(vb2_ioctl_create_bufs);

int vb2_ioctl_prepare_buf(struct file *file, void *priv,
                          struct v4l2_buffer *p)
{
        struct video_device *vdev = video_devdata(file);

        if (vb2_queue_is_busy(vdev, file))
                return -EBUSY;
        return vb2_prepare_buf(vdev->queue, p);
}
EXPORT_SYMBOL_GPL(vb2_ioctl_prepare_buf);

int vb2_ioctl_querybuf(struct file *file, void *priv, struct v4l2_buffer *p)
{
        struct video_device *vdev = video_devdata(file);

        /* No need to call vb2_queue_is_busy(), anyone can query buffers. */
        return vb2_querybuf(vdev->queue, p);
}
EXPORT_SYMBOL_GPL(vb2_ioctl_querybuf);

int vb2_ioctl_qbuf(struct file *file, void *priv, struct v4l2_buffer *p)
{
        struct video_device *vdev = video_devdata(file);

        if (vb2_queue_is_busy(vdev, file))
                return -EBUSY;
        return vb2_qbuf(vdev->queue, p);
}
EXPORT_SYMBOL_GPL(vb2_ioctl_qbuf);

int vb2_ioctl_dqbuf(struct file *file, void *priv, struct v4l2_buffer *p)
{
        struct video_device *vdev = video_devdata(file);

        if (vb2_queue_is_busy(vdev, file))
                return -EBUSY;
        return vb2_dqbuf(vdev->queue, p, file->f_flags & O_NONBLOCK);
}
EXPORT_SYMBOL_GPL(vb2_ioctl_dqbuf);

int vb2_ioctl_streamon(struct file *file, void *priv, enum v4l2_buf_type i)
{
        struct video_device *vdev = video_devdata(file);

        if (vb2_queue_is_busy(vdev, file))
                return -EBUSY;
        return vb2_streamon(vdev->queue, i);
}
EXPORT_SYMBOL_GPL(vb2_ioctl_streamon);

int vb2_ioctl_streamoff(struct file *file, void *priv, enum v4l2_buf_type i)
{
        struct video_device *vdev = video_devdata(file);

        if (vb2_queue_is_busy(vdev, file))
                return -EBUSY;
        return vb2_streamoff(vdev->queue, i);
}
EXPORT_SYMBOL_GPL(vb2_ioctl_streamoff);

int vb2_ioctl_expbuf(struct file *file, void *priv, struct v4l2_exportbuffer *p)
{
        struct video_device *vdev = video_devdata(file);

        if (vb2_queue_is_busy(vdev, file))
                return -EBUSY;
        return vb2_expbuf(vdev->queue, p);
}
EXPORT_SYMBOL_GPL(vb2_ioctl_expbuf);

/* v4l2_file_operations helpers */

int vb2_fop_mmap(struct file *file, struct vm_area_struct *vma)
{
        struct video_device *vdev = video_devdata(file);

        return vb2_mmap(vdev->queue, vma);
}
EXPORT_SYMBOL_GPL(vb2_fop_mmap);

int _vb2_fop_release(struct file *file, struct mutex *lock)
{
        struct video_device *vdev = video_devdata(file);

        if (lock)
                mutex_lock(lock);
        if (file->private_data == vdev->queue->owner) {
                vb2_queue_release(vdev->queue);
                vdev->queue->owner = NULL;
        }
        if (lock)
                mutex_unlock(lock);
        return v4l2_fh_release(file);
}
EXPORT_SYMBOL_GPL(_vb2_fop_release);

int vb2_fop_release(struct file *file)
{
        struct video_device *vdev = video_devdata(file);
        struct mutex *lock = vdev->queue->lock ? vdev->queue->lock : vdev->lock;

        return _vb2_fop_release(file, lock);
}
EXPORT_SYMBOL_GPL(vb2_fop_release);

ssize_t vb2_fop_write(struct file *file, const char __user *buf,
                size_t count, loff_t *ppos)
{
        struct video_device *vdev = video_devdata(file);
        struct mutex *lock = vdev->queue->lock ? vdev->queue->lock : vdev->lock;
        int err = -EBUSY;

        if (!(vdev->queue->io_modes & VB2_WRITE))
                return -EINVAL;
        if (lock && mutex_lock_interruptible(lock))
                return -ERESTARTSYS;
        if (vb2_queue_is_busy(vdev, file))
                goto exit;
        err = vb2_write(vdev->queue, buf, count, ppos,
                       file->f_flags & O_NONBLOCK);
        if (vdev->queue->fileio)
                vdev->queue->owner = file->private_data;
exit:
        if (lock)
                mutex_unlock(lock);
        return err;
}
EXPORT_SYMBOL_GPL(vb2_fop_write);

ssize_t vb2_fop_read(struct file *file, char __user *buf,
                size_t count, loff_t *ppos)
{
        struct video_device *vdev = video_devdata(file);
        struct mutex *lock = vdev->queue->lock ? vdev->queue->lock : vdev->lock;
        int err = -EBUSY;

        if (!(vdev->queue->io_modes & VB2_READ))
                return -EINVAL;
        if (lock && mutex_lock_interruptible(lock))
                return -ERESTARTSYS;
        if (vb2_queue_is_busy(vdev, file))
                goto exit;
        err = vb2_read(vdev->queue, buf, count, ppos,
                       file->f_flags & O_NONBLOCK);
        if (vdev->queue->fileio)
                vdev->queue->owner = file->private_data;
exit:
        if (lock)
                mutex_unlock(lock);
        return err;
}
EXPORT_SYMBOL_GPL(vb2_fop_read);

unsigned int vb2_fop_poll(struct file *file, poll_table *wait)
{
        struct video_device *vdev = video_devdata(file);
        struct vb2_queue *q = vdev->queue;
        struct mutex *lock = q->lock ? q->lock : vdev->lock;
        unsigned res;
        void *fileio;

        /*
         * If this helper doesn't know how to lock, then you shouldn't be using
         * it but you should write your own.
         */
        WARN_ON(!lock);

        if (lock && mutex_lock_interruptible(lock))
                return POLLERR;

        fileio = q->fileio;

        res = vb2_poll(vdev->queue, file, wait);

        /* If fileio was started, then we have a new queue owner. */
        if (!fileio && q->fileio)
                q->owner = file->private_data;
        if (lock)
                mutex_unlock(lock);
        return res;
}
EXPORT_SYMBOL_GPL(vb2_fop_poll);

#ifndef CONFIG_MMU
unsigned long vb2_fop_get_unmapped_area(struct file *file, unsigned long addr,
                unsigned long len, unsigned long pgoff, unsigned long flags)
{
        struct video_device *vdev = video_devdata(file);

        return vb2_get_unmapped_area(vdev->queue, addr, len, pgoff, flags);
}
EXPORT_SYMBOL_GPL(vb2_fop_get_unmapped_area);
#endif

/* vb2_ops helpers. Only use if vq->lock is non-NULL. */

void vb2_ops_wait_prepare(struct vb2_queue *vq)
{
        mutex_unlock(vq->lock);
}
EXPORT_SYMBOL_GPL(vb2_ops_wait_prepare);

void vb2_ops_wait_finish(struct vb2_queue *vq)
{
        mutex_lock(vq->lock);
}
EXPORT_SYMBOL_GPL(vb2_ops_wait_finish);

MODULE_DESCRIPTION("Driver helper framework for Video for Linux 2");
MODULE_AUTHOR("Pawel Osciak <pawel@osciak.com>, Marek Szyprowski");
MODULE_LICENSE("GPL");