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60063497a9
This allows us to move duplicated code in <asm/atomic.h> (atomic_inc_not_zero() for now) to <linux/atomic.h> Signed-off-by: Arun Sharma <asharma@fb.com> Reviewed-by: Eric Dumazet <eric.dumazet@gmail.com> Cc: Ingo Molnar <mingo@elte.hu> Cc: David Miller <davem@davemloft.net> Cc: Eric Dumazet <eric.dumazet@gmail.com> Acked-by: Mike Frysinger <vapier@gentoo.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
589 lines
15 KiB
C
589 lines
15 KiB
C
/*
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* uvc_queue.c -- USB Video Class driver - Buffers management
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*
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* Copyright (C) 2005-2010
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* Laurent Pinchart (laurent.pinchart@ideasonboard.com)
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation; either version 2 of the License, or
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* (at your option) any later version.
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*
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*/
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#include <linux/kernel.h>
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#include <linux/mm.h>
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#include <linux/list.h>
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#include <linux/module.h>
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#include <linux/usb.h>
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#include <linux/videodev2.h>
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#include <linux/vmalloc.h>
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#include <linux/wait.h>
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#include <linux/atomic.h>
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#include "uvc.h"
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/* ------------------------------------------------------------------------
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* Video buffers queue management.
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*
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* Video queues is initialized by uvc_queue_init(). The function performs
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* basic initialization of the uvc_video_queue struct and never fails.
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*
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* Video buffer allocation and freeing are performed by uvc_alloc_buffers and
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* uvc_free_buffers respectively. The former acquires the video queue lock,
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* while the later must be called with the lock held (so that allocation can
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* free previously allocated buffers). Trying to free buffers that are mapped
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* to user space will return -EBUSY.
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*
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* Video buffers are managed using two queues. However, unlike most USB video
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* drivers that use an in queue and an out queue, we use a main queue to hold
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* all queued buffers (both 'empty' and 'done' buffers), and an irq queue to
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* hold empty buffers. This design (copied from video-buf) minimizes locking
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* in interrupt, as only one queue is shared between interrupt and user
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* contexts.
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*
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* Use cases
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* ---------
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*
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* Unless stated otherwise, all operations that modify the irq buffers queue
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* are protected by the irq spinlock.
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*
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* 1. The user queues the buffers, starts streaming and dequeues a buffer.
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*
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* The buffers are added to the main and irq queues. Both operations are
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* protected by the queue lock, and the later is protected by the irq
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* spinlock as well.
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*
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* The completion handler fetches a buffer from the irq queue and fills it
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* with video data. If no buffer is available (irq queue empty), the handler
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* returns immediately.
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*
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* When the buffer is full, the completion handler removes it from the irq
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* queue, marks it as ready (UVC_BUF_STATE_DONE) and wakes its wait queue.
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* At that point, any process waiting on the buffer will be woken up. If a
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* process tries to dequeue a buffer after it has been marked ready, the
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* dequeing will succeed immediately.
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*
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* 2. Buffers are queued, user is waiting on a buffer and the device gets
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* disconnected.
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*
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* When the device is disconnected, the kernel calls the completion handler
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* with an appropriate status code. The handler marks all buffers in the
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* irq queue as being erroneous (UVC_BUF_STATE_ERROR) and wakes them up so
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* that any process waiting on a buffer gets woken up.
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*
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* Waking up up the first buffer on the irq list is not enough, as the
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* process waiting on the buffer might restart the dequeue operation
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* immediately.
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*
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*/
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static void
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uvc_queue_init(struct uvc_video_queue *queue, enum v4l2_buf_type type)
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{
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mutex_init(&queue->mutex);
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spin_lock_init(&queue->irqlock);
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INIT_LIST_HEAD(&queue->mainqueue);
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INIT_LIST_HEAD(&queue->irqqueue);
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queue->type = type;
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}
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/*
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* Free the video buffers.
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*
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* This function must be called with the queue lock held.
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*/
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static int uvc_free_buffers(struct uvc_video_queue *queue)
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{
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unsigned int i;
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for (i = 0; i < queue->count; ++i) {
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if (queue->buffer[i].vma_use_count != 0)
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return -EBUSY;
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}
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if (queue->count) {
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vfree(queue->mem);
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queue->count = 0;
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}
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return 0;
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}
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/*
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* Allocate the video buffers.
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*
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* Pages are reserved to make sure they will not be swapped, as they will be
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* filled in the URB completion handler.
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*
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* Buffers will be individually mapped, so they must all be page aligned.
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*/
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static int
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uvc_alloc_buffers(struct uvc_video_queue *queue, unsigned int nbuffers,
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unsigned int buflength)
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{
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unsigned int bufsize = PAGE_ALIGN(buflength);
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unsigned int i;
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void *mem = NULL;
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int ret;
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if (nbuffers > UVC_MAX_VIDEO_BUFFERS)
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nbuffers = UVC_MAX_VIDEO_BUFFERS;
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mutex_lock(&queue->mutex);
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if ((ret = uvc_free_buffers(queue)) < 0)
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goto done;
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/* Bail out if no buffers should be allocated. */
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if (nbuffers == 0)
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goto done;
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/* Decrement the number of buffers until allocation succeeds. */
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for (; nbuffers > 0; --nbuffers) {
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mem = vmalloc_32(nbuffers * bufsize);
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if (mem != NULL)
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break;
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}
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if (mem == NULL) {
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ret = -ENOMEM;
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goto done;
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}
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for (i = 0; i < nbuffers; ++i) {
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memset(&queue->buffer[i], 0, sizeof queue->buffer[i]);
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queue->buffer[i].buf.index = i;
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queue->buffer[i].buf.m.offset = i * bufsize;
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queue->buffer[i].buf.length = buflength;
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queue->buffer[i].buf.type = queue->type;
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queue->buffer[i].buf.sequence = 0;
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queue->buffer[i].buf.field = V4L2_FIELD_NONE;
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queue->buffer[i].buf.memory = V4L2_MEMORY_MMAP;
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queue->buffer[i].buf.flags = 0;
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init_waitqueue_head(&queue->buffer[i].wait);
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}
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queue->mem = mem;
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queue->count = nbuffers;
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queue->buf_size = bufsize;
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ret = nbuffers;
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done:
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mutex_unlock(&queue->mutex);
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return ret;
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}
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static void __uvc_query_buffer(struct uvc_buffer *buf,
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struct v4l2_buffer *v4l2_buf)
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{
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memcpy(v4l2_buf, &buf->buf, sizeof *v4l2_buf);
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if (buf->vma_use_count)
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v4l2_buf->flags |= V4L2_BUF_FLAG_MAPPED;
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switch (buf->state) {
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case UVC_BUF_STATE_ERROR:
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case UVC_BUF_STATE_DONE:
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v4l2_buf->flags |= V4L2_BUF_FLAG_DONE;
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break;
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case UVC_BUF_STATE_QUEUED:
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case UVC_BUF_STATE_ACTIVE:
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v4l2_buf->flags |= V4L2_BUF_FLAG_QUEUED;
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break;
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case UVC_BUF_STATE_IDLE:
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default:
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break;
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}
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}
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static int
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uvc_query_buffer(struct uvc_video_queue *queue, struct v4l2_buffer *v4l2_buf)
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{
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int ret = 0;
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mutex_lock(&queue->mutex);
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if (v4l2_buf->index >= queue->count) {
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ret = -EINVAL;
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goto done;
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}
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__uvc_query_buffer(&queue->buffer[v4l2_buf->index], v4l2_buf);
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done:
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mutex_unlock(&queue->mutex);
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return ret;
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}
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/*
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* Queue a video buffer. Attempting to queue a buffer that has already been
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* queued will return -EINVAL.
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*/
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static int
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uvc_queue_buffer(struct uvc_video_queue *queue, struct v4l2_buffer *v4l2_buf)
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{
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struct uvc_buffer *buf;
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unsigned long flags;
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int ret = 0;
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uvc_trace(UVC_TRACE_CAPTURE, "Queuing buffer %u.\n", v4l2_buf->index);
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if (v4l2_buf->type != queue->type ||
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v4l2_buf->memory != V4L2_MEMORY_MMAP) {
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uvc_trace(UVC_TRACE_CAPTURE, "[E] Invalid buffer type (%u) "
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"and/or memory (%u).\n", v4l2_buf->type,
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v4l2_buf->memory);
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return -EINVAL;
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}
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mutex_lock(&queue->mutex);
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if (v4l2_buf->index >= queue->count) {
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uvc_trace(UVC_TRACE_CAPTURE, "[E] Out of range index.\n");
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ret = -EINVAL;
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goto done;
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}
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buf = &queue->buffer[v4l2_buf->index];
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if (buf->state != UVC_BUF_STATE_IDLE) {
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uvc_trace(UVC_TRACE_CAPTURE, "[E] Invalid buffer state "
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"(%u).\n", buf->state);
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ret = -EINVAL;
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goto done;
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}
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if (v4l2_buf->type == V4L2_BUF_TYPE_VIDEO_OUTPUT &&
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v4l2_buf->bytesused > buf->buf.length) {
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uvc_trace(UVC_TRACE_CAPTURE, "[E] Bytes used out of bounds.\n");
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ret = -EINVAL;
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goto done;
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}
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if (v4l2_buf->type == V4L2_BUF_TYPE_VIDEO_CAPTURE)
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buf->buf.bytesused = 0;
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else
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buf->buf.bytesused = v4l2_buf->bytesused;
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spin_lock_irqsave(&queue->irqlock, flags);
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if (queue->flags & UVC_QUEUE_DISCONNECTED) {
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spin_unlock_irqrestore(&queue->irqlock, flags);
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ret = -ENODEV;
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goto done;
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}
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buf->state = UVC_BUF_STATE_QUEUED;
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ret = (queue->flags & UVC_QUEUE_PAUSED) != 0;
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queue->flags &= ~UVC_QUEUE_PAUSED;
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list_add_tail(&buf->stream, &queue->mainqueue);
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list_add_tail(&buf->queue, &queue->irqqueue);
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spin_unlock_irqrestore(&queue->irqlock, flags);
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done:
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mutex_unlock(&queue->mutex);
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return ret;
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}
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static int uvc_queue_waiton(struct uvc_buffer *buf, int nonblocking)
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{
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if (nonblocking) {
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return (buf->state != UVC_BUF_STATE_QUEUED &&
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buf->state != UVC_BUF_STATE_ACTIVE)
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? 0 : -EAGAIN;
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}
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return wait_event_interruptible(buf->wait,
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buf->state != UVC_BUF_STATE_QUEUED &&
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buf->state != UVC_BUF_STATE_ACTIVE);
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}
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/*
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* Dequeue a video buffer. If nonblocking is false, block until a buffer is
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* available.
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*/
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static int
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uvc_dequeue_buffer(struct uvc_video_queue *queue, struct v4l2_buffer *v4l2_buf,
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int nonblocking)
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{
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struct uvc_buffer *buf;
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int ret = 0;
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if (v4l2_buf->type != queue->type ||
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v4l2_buf->memory != V4L2_MEMORY_MMAP) {
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uvc_trace(UVC_TRACE_CAPTURE, "[E] Invalid buffer type (%u) "
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"and/or memory (%u).\n", v4l2_buf->type,
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v4l2_buf->memory);
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return -EINVAL;
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}
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mutex_lock(&queue->mutex);
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if (list_empty(&queue->mainqueue)) {
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uvc_trace(UVC_TRACE_CAPTURE, "[E] Empty buffer queue.\n");
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ret = -EINVAL;
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goto done;
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}
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buf = list_first_entry(&queue->mainqueue, struct uvc_buffer, stream);
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if ((ret = uvc_queue_waiton(buf, nonblocking)) < 0)
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goto done;
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uvc_trace(UVC_TRACE_CAPTURE, "Dequeuing buffer %u (%u, %u bytes).\n",
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buf->buf.index, buf->state, buf->buf.bytesused);
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switch (buf->state) {
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case UVC_BUF_STATE_ERROR:
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uvc_trace(UVC_TRACE_CAPTURE, "[W] Corrupted data "
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"(transmission error).\n");
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ret = -EIO;
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case UVC_BUF_STATE_DONE:
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buf->state = UVC_BUF_STATE_IDLE;
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break;
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case UVC_BUF_STATE_IDLE:
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case UVC_BUF_STATE_QUEUED:
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case UVC_BUF_STATE_ACTIVE:
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default:
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uvc_trace(UVC_TRACE_CAPTURE, "[E] Invalid buffer state %u "
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"(driver bug?).\n", buf->state);
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ret = -EINVAL;
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goto done;
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}
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list_del(&buf->stream);
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__uvc_query_buffer(buf, v4l2_buf);
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done:
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mutex_unlock(&queue->mutex);
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return ret;
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}
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/*
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* Poll the video queue.
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*
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* This function implements video queue polling and is intended to be used by
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* the device poll handler.
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*/
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static unsigned int
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uvc_queue_poll(struct uvc_video_queue *queue, struct file *file,
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poll_table *wait)
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{
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struct uvc_buffer *buf;
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unsigned int mask = 0;
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mutex_lock(&queue->mutex);
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if (list_empty(&queue->mainqueue))
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goto done;
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buf = list_first_entry(&queue->mainqueue, struct uvc_buffer, stream);
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poll_wait(file, &buf->wait, wait);
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if (buf->state == UVC_BUF_STATE_DONE ||
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buf->state == UVC_BUF_STATE_ERROR)
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mask |= POLLOUT | POLLWRNORM;
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done:
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mutex_unlock(&queue->mutex);
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return mask;
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}
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/*
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* VMA operations.
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*/
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static void uvc_vm_open(struct vm_area_struct *vma)
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{
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struct uvc_buffer *buffer = vma->vm_private_data;
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buffer->vma_use_count++;
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}
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static void uvc_vm_close(struct vm_area_struct *vma)
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{
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struct uvc_buffer *buffer = vma->vm_private_data;
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buffer->vma_use_count--;
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}
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static struct vm_operations_struct uvc_vm_ops = {
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.open = uvc_vm_open,
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.close = uvc_vm_close,
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};
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/*
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* Memory-map a buffer.
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*
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* This function implements video buffer memory mapping and is intended to be
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* used by the device mmap handler.
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*/
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static int
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uvc_queue_mmap(struct uvc_video_queue *queue, struct vm_area_struct *vma)
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{
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struct uvc_buffer *uninitialized_var(buffer);
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struct page *page;
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unsigned long addr, start, size;
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unsigned int i;
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int ret = 0;
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start = vma->vm_start;
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size = vma->vm_end - vma->vm_start;
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mutex_lock(&queue->mutex);
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for (i = 0; i < queue->count; ++i) {
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buffer = &queue->buffer[i];
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if ((buffer->buf.m.offset >> PAGE_SHIFT) == vma->vm_pgoff)
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break;
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}
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if (i == queue->count || size != queue->buf_size) {
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ret = -EINVAL;
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goto done;
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}
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/*
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* VM_IO marks the area as being an mmaped region for I/O to a
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* device. It also prevents the region from being core dumped.
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*/
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vma->vm_flags |= VM_IO;
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addr = (unsigned long)queue->mem + buffer->buf.m.offset;
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while (size > 0) {
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page = vmalloc_to_page((void *)addr);
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if ((ret = vm_insert_page(vma, start, page)) < 0)
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goto done;
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start += PAGE_SIZE;
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addr += PAGE_SIZE;
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size -= PAGE_SIZE;
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}
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vma->vm_ops = &uvc_vm_ops;
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vma->vm_private_data = buffer;
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uvc_vm_open(vma);
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done:
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mutex_unlock(&queue->mutex);
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return ret;
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}
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/*
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* Cancel the video buffers queue.
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*
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* Cancelling the queue marks all buffers on the irq queue as erroneous,
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* wakes them up and removes them from the queue.
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*
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* If the disconnect parameter is set, further calls to uvc_queue_buffer will
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* fail with -ENODEV.
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*
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* This function acquires the irq spinlock and can be called from interrupt
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* context.
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*/
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static void uvc_queue_cancel(struct uvc_video_queue *queue, int disconnect)
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{
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struct uvc_buffer *buf;
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unsigned long flags;
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spin_lock_irqsave(&queue->irqlock, flags);
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while (!list_empty(&queue->irqqueue)) {
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buf = list_first_entry(&queue->irqqueue, struct uvc_buffer,
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queue);
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list_del(&buf->queue);
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buf->state = UVC_BUF_STATE_ERROR;
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wake_up(&buf->wait);
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}
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/* This must be protected by the irqlock spinlock to avoid race
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* conditions between uvc_queue_buffer and the disconnection event that
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* could result in an interruptible wait in uvc_dequeue_buffer. Do not
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* blindly replace this logic by checking for the UVC_DEV_DISCONNECTED
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* state outside the queue code.
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*/
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if (disconnect)
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queue->flags |= UVC_QUEUE_DISCONNECTED;
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spin_unlock_irqrestore(&queue->irqlock, flags);
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}
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/*
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* Enable or disable the video buffers queue.
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*
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* The queue must be enabled before starting video acquisition and must be
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* 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 initializes parameters (such as sequence number,
|
|
* sync pattern, ...). If the queue is already enabled, return -EBUSY.
|
|
*
|
|
* 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.
|
|
*/
|
|
static int uvc_queue_enable(struct uvc_video_queue *queue, int enable)
|
|
{
|
|
unsigned int i;
|
|
int ret = 0;
|
|
|
|
mutex_lock(&queue->mutex);
|
|
if (enable) {
|
|
if (uvc_queue_streaming(queue)) {
|
|
ret = -EBUSY;
|
|
goto done;
|
|
}
|
|
queue->sequence = 0;
|
|
queue->flags |= UVC_QUEUE_STREAMING;
|
|
queue->buf_used = 0;
|
|
} else {
|
|
uvc_queue_cancel(queue, 0);
|
|
INIT_LIST_HEAD(&queue->mainqueue);
|
|
|
|
for (i = 0; i < queue->count; ++i)
|
|
queue->buffer[i].state = UVC_BUF_STATE_IDLE;
|
|
|
|
queue->flags &= ~UVC_QUEUE_STREAMING;
|
|
}
|
|
|
|
done:
|
|
mutex_unlock(&queue->mutex);
|
|
return ret;
|
|
}
|
|
|
|
static 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_INCOMPLETE) &&
|
|
buf->buf.length != buf->buf.bytesused) {
|
|
buf->state = UVC_BUF_STATE_QUEUED;
|
|
buf->buf.bytesused = 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->buf.sequence = queue->sequence++;
|
|
do_gettimeofday(&buf->buf.timestamp);
|
|
|
|
wake_up(&buf->wait);
|
|
return nextbuf;
|
|
}
|
|
|
|
static struct uvc_buffer *uvc_queue_head(struct uvc_video_queue *queue)
|
|
{
|
|
struct uvc_buffer *buf = NULL;
|
|
|
|
if (!list_empty(&queue->irqqueue))
|
|
buf = list_first_entry(&queue->irqqueue, struct uvc_buffer,
|
|
queue);
|
|
else
|
|
queue->flags |= UVC_QUEUE_PAUSED;
|
|
|
|
return buf;
|
|
}
|
|
|