diff options
Diffstat (limited to 'drivers/media/video/uvc/uvc_queue.c')
| -rw-r--r-- | drivers/media/video/uvc/uvc_queue.c | 477 |
1 files changed, 477 insertions, 0 deletions
diff --git a/drivers/media/video/uvc/uvc_queue.c b/drivers/media/video/uvc/uvc_queue.c new file mode 100644 index 0000000..0923f0e --- /dev/null +++ b/drivers/media/video/uvc/uvc_queue.c @@ -0,0 +1,477 @@ +/* + * uvc_queue.c -- USB Video Class driver - Buffers management + * + * Copyright (C) 2005-2008 + * Laurent Pinchart (laurent.pinchart@skynet.be) + * + * 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/kernel.h> +#include <linux/version.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 <asm/atomic.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 buffer allocation and freeing are performed by uvc_alloc_buffers and + * uvc_free_buffers respectively. The former acquires the video queue lock, + * while the later must be called with the lock held (so that allocation can + * free previously allocated buffers). Trying to free buffers that are mapped + * to user space will return -EBUSY. + * + * Video buffers are managed using two queues. However, unlike most USB video + * drivers which use an in queue and an out queue, we use a main queue which + * holds all queued buffers (both 'empty' and 'done' buffers), and an irq + * queue which holds empty buffers. This design (copied from video-buf) + * minimizes locking in interrupt, as only one queue is shared between + * interrupt and user contexts. + * + * Use cases + * --------- + * + * Unless stated otherwise, all operations which modify the irq buffers queue + * are protected by the irq spinlock. + * + * 1. The user queues the buffers, starts streaming and dequeues a buffer. + * + * The buffers are added to the main and irq queues. Both operations are + * protected by the queue lock, and the latert is protected by the irq + * spinlock as well. + * + * The completion handler fetches a buffer from the irq queue and fills it + * with video data. If no buffer is available (irq queue empty), the handler + * returns immediately. + * + * When the buffer is full, the completion handler removes it from the irq + * queue, marks it as ready (UVC_BUF_STATE_DONE) and wake its wait queue. + * At that point, any process waiting on the buffer will be woken up. If a + * process tries to dequeue a buffer after it has been marked ready, the + * dequeing will succeed immediately. + * + * 2. Buffers are queued, user is waiting on a buffer and the device gets + * disconnected. + * + * When the device is disconnected, the kernel calls the completion handler + * with an appropriate status code. The handler marks all buffers in the + * irq queue as being erroneous (UVC_BUF_STATE_ERROR) and wakes them up so + * that any process waiting on a buffer gets woken up. + * + * Waking up up the first buffer on the irq list is not enough, as the + * process waiting on the buffer might restart the dequeue operation + * immediately. + * + */ + +void uvc_queue_init(struct uvc_video_queue *queue) +{ + mutex_init(&queue->mutex); + spin_lock_init(&queue->irqlock); + INIT_LIST_HEAD(&queue->mainqueue); + INIT_LIST_HEAD(&queue->irqqueue); +} + +/* + * Allocate the video buffers. + * + * Pages are reserved to make sure they will not be swaped, as they will be + * filled in URB completion handler. + * + * Buffers will be individually mapped, so they must all be page aligned. + */ +int uvc_alloc_buffers(struct uvc_video_queue *queue, unsigned int nbuffers, + unsigned int buflength) +{ + unsigned int bufsize = PAGE_ALIGN(buflength); + unsigned int i; + void *mem = NULL; + int ret; + + if (nbuffers > UVC_MAX_VIDEO_BUFFERS) + nbuffers = UVC_MAX_VIDEO_BUFFERS; + + mutex_lock(&queue->mutex); + + if ((ret = uvc_free_buffers(queue)) < 0) + goto done; + + /* Bail out if no buffers should be allocated. */ + if (nbuffers == 0) + goto done; + + /* Decrement the number of buffers until allocation succeeds. */ + for (; nbuffers > 0; --nbuffers) { + mem = vmalloc_32(nbuffers * bufsize); + if (mem != NULL) + break; + } + + if (mem == NULL) { + ret = -ENOMEM; + goto done; + } + + for (i = 0; i < nbuffers; ++i) { + memset(&queue->buffer[i], 0, sizeof queue->buffer[i]); + queue->buffer[i].buf.index = i; + queue->buffer[i].buf.m.offset = i * bufsize; + queue->buffer[i].buf.length = buflength; + queue->buffer[i].buf.type = V4L2_BUF_TYPE_VIDEO_CAPTURE; + queue->buffer[i].buf.sequence = 0; + queue->buffer[i].buf.field = V4L2_FIELD_NONE; + queue->buffer[i].buf.memory = V4L2_MEMORY_MMAP; + queue->buffer[i].buf.flags = 0; + init_waitqueue_head(&queue->buffer[i].wait); + } + + queue->mem = mem; + queue->count = nbuffers; + queue->buf_size = bufsize; + ret = nbuffers; + +done: + mutex_unlock(&queue->mutex); + return ret; +} + +/* + * Free the video buffers. + * + * This function must be called with the queue lock held. + */ +int uvc_free_buffers(struct uvc_video_queue *queue) +{ + unsigned int i; + + for (i = 0; i < queue->count; ++i) { + if (queue->buffer[i].vma_use_count != 0) + return -EBUSY; + } + + if (queue->count) { + vfree(queue->mem); + queue->count = 0; + } + + return 0; +} + +static void __uvc_query_buffer(struct uvc_buffer *buf, + struct v4l2_buffer *v4l2_buf) +{ + memcpy(v4l2_buf, &buf->buf, sizeof *v4l2_buf); + + if (buf->vma_use_count) + v4l2_buf->flags |= V4L2_BUF_FLAG_MAPPED; + + switch (buf->state) { + case UVC_BUF_STATE_ERROR: + case UVC_BUF_STATE_DONE: + v4l2_buf->flags |= V4L2_BUF_FLAG_DONE; + break; + case UVC_BUF_STATE_QUEUED: + case UVC_BUF_STATE_ACTIVE: + v4l2_buf->flags |= V4L2_BUF_FLAG_QUEUED; + break; + case UVC_BUF_STATE_IDLE: + default: + break; + } +} + +int uvc_query_buffer(struct uvc_video_queue *queue, + struct v4l2_buffer *v4l2_buf) +{ + int ret = 0; + + mutex_lock(&queue->mutex); + if (v4l2_buf->index >= queue->count) { + ret = -EINVAL; + goto done; + } + + __uvc_query_buffer(&queue->buffer[v4l2_buf->index], v4l2_buf); + +done: + mutex_unlock(&queue->mutex); + return ret; +} + +/* + * Queue a video buffer. Attempting to queue a buffer that has already been + * queued will return -EINVAL. + */ +int uvc_queue_buffer(struct uvc_video_queue *queue, + struct v4l2_buffer *v4l2_buf) +{ + struct uvc_buffer *buf; + unsigned long flags; + int ret = 0; + + uvc_trace(UVC_TRACE_CAPTURE, "Queuing buffer %u.\n", v4l2_buf->index); + + if (v4l2_buf->type != V4L2_BUF_TYPE_VIDEO_CAPTURE || + v4l2_buf->memory != V4L2_MEMORY_MMAP) { + uvc_trace(UVC_TRACE_CAPTURE, "[E] Invalid buffer type (%u) " + "and/or memory (%u).\n", v4l2_buf->type, + v4l2_buf->memory); + return -EINVAL; + } + + mutex_lock(&queue->mutex); + if (v4l2_buf->index >= queue->count) { + uvc_trace(UVC_TRACE_CAPTURE, "[E] Out of range index.\n"); + ret = -EINVAL; + goto done; + } + + buf = &queue->buffer[v4l2_buf->index]; + if (buf->state != UVC_BUF_STATE_IDLE) { + uvc_trace(UVC_TRACE_CAPTURE, "[E] Invalid buffer state " + "(%u).\n", buf->state); + ret = -EINVAL; + goto done; + } + + spin_lock_irqsave(&queue->irqlock, flags); + if (queue->flags & UVC_QUEUE_DISCONNECTED) { + spin_unlock_irqrestore(&queue->irqlock, flags); + ret = -ENODEV; + goto done; + } + buf->state = UVC_BUF_STATE_QUEUED; + buf->buf.bytesused = 0; + list_add_tail(&buf->stream, &queue->mainqueue); + list_add_tail(&buf->queue, &queue->irqqueue); + spin_unlock_irqrestore(&queue->irqlock, flags); + +done: + mutex_unlock(&queue->mutex); + return ret; +} + +static int uvc_queue_waiton(struct uvc_buffer *buf, int nonblocking) +{ + if (nonblocking) { + return (buf->state != UVC_BUF_STATE_QUEUED && + buf->state != UVC_BUF_STATE_ACTIVE) + ? 0 : -EAGAIN; + } + + return wait_event_interruptible(buf->wait, + buf->state != UVC_BUF_STATE_QUEUED && + buf->state != UVC_BUF_STATE_ACTIVE); +} + +/* + * Dequeue a video buffer. If nonblocking is false, block until a buffer is + * available. + */ +int uvc_dequeue_buffer(struct uvc_video_queue *queue, + struct v4l2_buffer *v4l2_buf, int nonblocking) +{ + struct uvc_buffer *buf; + int ret = 0; + + if (v4l2_buf->type != V4L2_BUF_TYPE_VIDEO_CAPTURE || + v4l2_buf->memory != V4L2_MEMORY_MMAP) { + uvc_trace(UVC_TRACE_CAPTURE, "[E] Invalid buffer type (%u) " + "and/or memory (%u).\n", v4l2_buf->type, + v4l2_buf->memory); + return -EINVAL; + } + + mutex_lock(&queue->mutex); + if (list_empty(&queue->mainqueue)) { + uvc_trace(UVC_TRACE_CAPTURE, "[E] Empty buffer queue.\n"); + ret = -EINVAL; + goto done; + } + + buf = list_first_entry(&queue->mainqueue, struct uvc_buffer, stream); + if ((ret = uvc_queue_waiton(buf, nonblocking)) < 0) + goto done; + + uvc_trace(UVC_TRACE_CAPTURE, "Dequeuing buffer %u (%u, %u bytes).\n", + buf->buf.index, buf->state, buf->buf.bytesused); + + switch (buf->state) { + case UVC_BUF_STATE_ERROR: + uvc_trace(UVC_TRACE_CAPTURE, "[W] Corrupted data " + "(transmission error).\n"); + ret = -EIO; + case UVC_BUF_STATE_DONE: + buf->state = UVC_BUF_STATE_IDLE; + break; + + case UVC_BUF_STATE_IDLE: + case UVC_BUF_STATE_QUEUED: + case UVC_BUF_STATE_ACTIVE: + default: + uvc_trace(UVC_TRACE_CAPTURE, "[E] Invalid buffer state %u " + "(driver bug?).\n", buf->state); + ret = -EINVAL; + goto done; + } + + list_del(&buf->stream); + __uvc_query_buffer(buf, v4l2_buf); + +done: + mutex_unlock(&queue->mutex); + return ret; +} + +/* + * Poll the video queue. + * + * This function implements video queue polling and is intended to be used by + * the device poll handler. + */ +unsigned int uvc_queue_poll(struct uvc_video_queue *queue, struct file *file, + poll_table *wait) +{ + struct uvc_buffer *buf; + unsigned int mask = 0; + + mutex_lock(&queue->mutex); + if (list_empty(&queue->mainqueue)) { + mask |= POLLERR; + goto done; + } + buf = list_first_entry(&queue->mainqueue, struct uvc_buffer, stream); + + poll_wait(file, &buf->wait, wait); + if (buf->state == UVC_BUF_STATE_DONE || + buf->state == UVC_BUF_STATE_ERROR) + mask |= POLLIN | POLLRDNORM; + +done: + mutex_unlock(&queue->mutex); + return mask; +} + +/* + * 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 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. + */ +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; + } 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; +} + +/* + * Cancel the video buffers queue. + * + * Cancelling the queue marks all buffers on the irq queue as erroneous, + * wakes them up and remove 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; + wake_up(&buf->wait); + } + /* This must be protected by the irqlock spinlock to avoid race + * conditions between uvc_queue_buffer 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_DEV_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_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; +} |
