V4L/DVB (8145a): USB Video Class driver

This driver supports video input devices compliant with the USB Video Class
specification. This means lots of currently manufactured webcams, and probably
most of the future ones.

Signed-off-by: Laurent Pinchart <laurent.pinchart@skynet.be>
Signed-off-by: Mauro Carvalho Chehab <mchehab@infradead.org>

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;
+}