uvc_queue.c

Go to the documentation of this file.

/*
 *      uvc_queue.c  --  USB Video Class driver - Buffers management
 *
 *      Copyright (C) 2005-2010
 *          Laurent Pinchart ([email protected])
 *
 *      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/atomic.h>
#include <linux/kernel.h>
#include <linux/mm.h>
#include <linux/list.h>
#include <linux/module.h>
#include <linux/usb.h>
#include <linux/videodev2.h>
#include <linux/vmalloc.h>
#include <linux/wait.h>
#include <media/videobuf2-vmalloc.h>

#include "uvcvideo.h"

/* ------------------------------------------------------------------------
 * Video buffers queue management.
 *
 * Video queues is initialized by uvc_queue_init(). The function performs
 * basic initialization of the uvc_video_queue struct and never fails.
 *
 * Video buffers are managed by videobuf2. The driver uses a mutex to protect
 * the videobuf2 queue operations by serializing calls to videobuf2 and a
 * spinlock to protect the IRQ queue that holds the buffers to be processed by
 * the driver.
 */

/* -----------------------------------------------------------------------------
 * videobuf2 queue operations
 */

static int uvc_queue_setup(struct vb2_queue *vq, const struct v4l2_format *fmt,
               unsigned int *nbuffers, unsigned int *nplanes,
               unsigned int sizes[], void *alloc_ctxs[])
{
    struct uvc_video_queue *queue = vb2_get_drv_priv(vq);
    struct uvc_streaming *stream =
            container_of(queue, struct uvc_streaming, queue);

    if (*nbuffers > UVC_MAX_VIDEO_BUFFERS)
        *nbuffers = UVC_MAX_VIDEO_BUFFERS;

    *nplanes = 1;

    sizes[0] = stream->ctrl.dwMaxVideoFrameSize;

    return 0;
}

static int uvc_buffer_prepare(struct vb2_buffer *vb)
{
    struct uvc_video_queue *queue = vb2_get_drv_priv(vb->vb2_queue);
    struct uvc_buffer *buf = container_of(vb, struct uvc_buffer, buf);

    if (vb->v4l2_buf.type == V4L2_BUF_TYPE_VIDEO_OUTPUT &&
        vb2_get_plane_payload(vb, 0) > vb2_plane_size(vb, 0)) {
        uvc_trace(UVC_TRACE_CAPTURE, "[E] Bytes used out of bounds.\n");
        return -EINVAL;
    }

    if (unlikely(queue->flags & UVC_QUEUE_DISCONNECTED))
        return -ENODEV;

    buf->state = UVC_BUF_STATE_QUEUED;
    buf->error = 0;
    buf->mem = vb2_plane_vaddr(vb, 0);
    buf->length = vb2_plane_size(vb, 0);
    if (vb->v4l2_buf.type == V4L2_BUF_TYPE_VIDEO_CAPTURE)
        buf->bytesused = 0;
    else
        buf->bytesused = vb2_get_plane_payload(vb, 0);

    return 0;
}

static void uvc_buffer_queue(struct vb2_buffer *vb)
{
    struct uvc_video_queue *queue = vb2_get_drv_priv(vb->vb2_queue);
    struct uvc_buffer *buf = container_of(vb, struct uvc_buffer, buf);
    unsigned long flags;

    spin_lock_irqsave(&queue->irqlock, flags);
    if (likely(!(queue->flags & UVC_QUEUE_DISCONNECTED))) {
        list_add_tail(&buf->queue, &queue->irqqueue);
    } else {
        /* If the device is disconnected return the buffer to userspace
         * directly. The next QBUF call will fail with -ENODEV.
         */
        buf->state = UVC_BUF_STATE_ERROR;
        vb2_buffer_done(&buf->buf, VB2_BUF_STATE_ERROR);
    }

    spin_unlock_irqrestore(&queue->irqlock, flags);
}

static int uvc_buffer_finish(struct vb2_buffer *vb)
{
    struct uvc_video_queue *queue = vb2_get_drv_priv(vb->vb2_queue);
    struct uvc_streaming *stream =
            container_of(queue, struct uvc_streaming, queue);
    struct uvc_buffer *buf = container_of(vb, struct uvc_buffer, buf);

    uvc_video_clock_update(stream, &vb->v4l2_buf, buf);
    return 0;
}

static struct vb2_ops uvc_queue_qops = {
    .queue_setup = uvc_queue_setup,
    .buf_prepare = uvc_buffer_prepare,
    .buf_queue = uvc_buffer_queue,
    .buf_finish = uvc_buffer_finish,
};

int uvc_queue_init(struct uvc_video_queue *queue, enum v4l2_buf_type type,
            int drop_corrupted)
{
    int ret;

    queue->queue.type = type;
    queue->queue.io_modes = VB2_MMAP | VB2_USERPTR;
    queue->queue.drv_priv = queue;
    queue->queue.buf_struct_size = sizeof(struct uvc_buffer);
    queue->queue.ops = &uvc_queue_qops;
    queue->queue.mem_ops = &vb2_vmalloc_memops;
    ret = vb2_queue_init(&queue->queue);
    if (ret)
        return ret;

    mutex_init(&queue->mutex);
    spin_lock_init(&queue->irqlock);
    INIT_LIST_HEAD(&queue->irqqueue);
    queue->flags = drop_corrupted ? UVC_QUEUE_DROP_CORRUPTED : 0;

    return 0;
}

/* -----------------------------------------------------------------------------
 * V4L2 queue operations
 */

int uvc_alloc_buffers(struct uvc_video_queue *queue,
              struct v4l2_requestbuffers *rb)
{
    int ret;

    mutex_lock(&queue->mutex);
    ret = vb2_reqbufs(&queue->queue, rb);
    mutex_unlock(&queue->mutex);

    return ret ? ret : rb->count;
}

void uvc_free_buffers(struct uvc_video_queue *queue)
{
    mutex_lock(&queue->mutex);
    vb2_queue_release(&queue->queue);
    mutex_unlock(&queue->mutex);
}

int uvc_query_buffer(struct uvc_video_queue *queue, struct v4l2_buffer *buf)
{
    int ret;

    mutex_lock(&queue->mutex);
    ret = vb2_querybuf(&queue->queue, buf);
    mutex_unlock(&queue->mutex);

    return ret;
}

int uvc_queue_buffer(struct uvc_video_queue *queue, struct v4l2_buffer *buf)
{
    int ret;

    mutex_lock(&queue->mutex);
    ret = vb2_qbuf(&queue->queue, buf);
    mutex_unlock(&queue->mutex);

    return ret;
}

int uvc_dequeue_buffer(struct uvc_video_queue *queue, struct v4l2_buffer *buf,
               int nonblocking)
{
    int ret;

    mutex_lock(&queue->mutex);
    ret = vb2_dqbuf(&queue->queue, buf, nonblocking);
    mutex_unlock(&queue->mutex);

    return ret;
}

int uvc_queue_mmap(struct uvc_video_queue *queue, struct vm_area_struct *vma)
{
    int ret;

    mutex_lock(&queue->mutex);
    ret = vb2_mmap(&queue->queue, vma);
    mutex_unlock(&queue->mutex);

    return ret;
}

#ifndef CONFIG_MMU
unsigned long uvc_queue_get_unmapped_area(struct uvc_video_queue *queue,
        unsigned long pgoff)
{
    unsigned long ret;

    mutex_lock(&queue->mutex);
    ret = vb2_get_unmapped_area(&queue->queue, 0, 0, pgoff, 0);
    mutex_unlock(&queue->mutex);
    return ret;
}
#endif

unsigned int uvc_queue_poll(struct uvc_video_queue *queue, struct file *file,
                poll_table *wait)
{
    unsigned int ret;

    mutex_lock(&queue->mutex);
    ret = vb2_poll(&queue->queue, file, wait);
    mutex_unlock(&queue->mutex);

    return ret;
}

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

/*
 * Check if buffers have been allocated.
 */
int uvc_queue_allocated(struct uvc_video_queue *queue)
{
    int allocated;

    mutex_lock(&queue->mutex);
    allocated = vb2_is_busy(&queue->queue);
    mutex_unlock(&queue->mutex);

    return allocated;
}

/*
 * Enable or disable the video buffers queue.
 *
 * The queue must be enabled before starting video acquisition and must be
 * disabled after stopping it. This ensures that the video buffers queue
 * state can be properly initialized before buffers are accessed from the
 * interrupt handler.
 *
 * Enabling the video queue returns -EBUSY if the queue is already enabled.
 *
 * Disabling the video queue cancels the queue and removes all buffers from
 * the main queue.
 *
 * This function can't be called from interrupt context. Use
 * uvc_queue_cancel() instead.
 */
int uvc_queue_enable(struct uvc_video_queue *queue, int enable)
{
    unsigned long flags;
    int ret;

    mutex_lock(&queue->mutex);
    if (enable) {
        ret = vb2_streamon(&queue->queue, queue->queue.type);
        if (ret < 0)
            goto done;

        queue->buf_used = 0;
    } else {
        ret = vb2_streamoff(&queue->queue, queue->queue.type);
        if (ret < 0)
            goto done;

        spin_lock_irqsave(&queue->irqlock, flags);
        INIT_LIST_HEAD(&queue->irqqueue);
        spin_unlock_irqrestore(&queue->irqlock, flags);
    }

done:
    mutex_unlock(&queue->mutex);
    return ret;
}

/*
 * Cancel the video buffers queue.
 *
 * Cancelling the queue marks all buffers on the irq queue as erroneous,
 * wakes them up and removes them from the queue.
 *
 * If the disconnect parameter is set, further calls to uvc_queue_buffer will
 * fail with -ENODEV.
 *
 * This function acquires the irq spinlock and can be called from interrupt
 * context.
 */
void uvc_queue_cancel(struct uvc_video_queue *queue, int disconnect)
{
    struct uvc_buffer *buf;
    unsigned long flags;

    spin_lock_irqsave(&queue->irqlock, flags);
    while (!list_empty(&queue->irqqueue)) {
        buf = list_first_entry(&queue->irqqueue, struct uvc_buffer,
                       queue);
        list_del(&buf->queue);
        buf->state = UVC_BUF_STATE_ERROR;
        vb2_buffer_done(&buf->buf, VB2_BUF_STATE_ERROR);
    }
    /* This must be protected by the irqlock spinlock to avoid race
     * conditions between uvc_buffer_queue and the disconnection event that
     * could result in an interruptible wait in uvc_dequeue_buffer. Do not
     * blindly replace this logic by checking for the UVC_QUEUE_DISCONNECTED
     * state outside the queue code.
     */
    if (disconnect)
        queue->flags |= UVC_QUEUE_DISCONNECTED;
    spin_unlock_irqrestore(&queue->irqlock, flags);
}

struct uvc_buffer *uvc_queue_next_buffer(struct uvc_video_queue *queue,
        struct uvc_buffer *buf)
{
    struct uvc_buffer *nextbuf;
    unsigned long flags;

    if ((queue->flags & UVC_QUEUE_DROP_CORRUPTED) && buf->error) {
        buf->error = 0;
        buf->state = UVC_BUF_STATE_QUEUED;
        buf->bytesused = 0;
        vb2_set_plane_payload(&buf->buf, 0, 0);
        return buf;
    }

    spin_lock_irqsave(&queue->irqlock, flags);
    list_del(&buf->queue);
    if (!list_empty(&queue->irqqueue))
        nextbuf = list_first_entry(&queue->irqqueue, struct uvc_buffer,
                       queue);
    else
        nextbuf = NULL;
    spin_unlock_irqrestore(&queue->irqlock, flags);

    buf->state = buf->error ? VB2_BUF_STATE_ERROR : UVC_BUF_STATE_DONE;
    vb2_set_plane_payload(&buf->buf, 0, buf->bytesused);
    vb2_buffer_done(&buf->buf, VB2_BUF_STATE_DONE);

    return nextbuf;
}