--- /dev/null
+/*
+ * uvc_video.c -- USB Video Class Gadget driver
+ *
+ * Copyright (C) 2009-2010
+ * Laurent Pinchart (laurent.pinchart@ideasonboard.com)
+ *
+ * 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/device.h>
+#include <linux/errno.h>
+#include <linux/usb/ch9.h>
+#include <linux/usb/gadget.h>
+#include <linux/usb/video.h>
+
+#include <media/v4l2-dev.h>
+
+#include "uvc.h"
+#include "uvc_queue.h"
+#include "uvc_video.h"
+
+/* --------------------------------------------------------------------------
+ * Video codecs
+ */
+
+static int
+uvc_video_encode_header(struct uvc_video *video, struct uvc_buffer *buf,
+ u8 *data, int len)
+{
+ data[0] = 2;
+ data[1] = UVC_STREAM_EOH | video->fid;
+
+ if (buf->bytesused - video->queue.buf_used <= len - 2)
+ data[1] |= UVC_STREAM_EOF;
+
+ return 2;
+}
+
+static int
+uvc_video_encode_data(struct uvc_video *video, struct uvc_buffer *buf,
+ u8 *data, int len)
+{
+ struct uvc_video_queue *queue = &video->queue;
+ unsigned int nbytes;
+ void *mem;
+
+ /* Copy video data to the USB buffer. */
+ mem = buf->mem + queue->buf_used;
+ nbytes = min((unsigned int)len, buf->bytesused - queue->buf_used);
+
+ memcpy(data, mem, nbytes);
+ queue->buf_used += nbytes;
+
+ return nbytes;
+}
+
+static void
+uvc_video_encode_bulk(struct usb_request *req, struct uvc_video *video,
+ struct uvc_buffer *buf)
+{
+ void *mem = req->buf;
+ int len = video->req_size;
+ int ret;
+
+ /* Add a header at the beginning of the payload. */
+ if (video->payload_size == 0) {
+ ret = uvc_video_encode_header(video, buf, mem, len);
+ video->payload_size += ret;
+ mem += ret;
+ len -= ret;
+ }
+
+ /* Process video data. */
+ len = min((int)(video->max_payload_size - video->payload_size), len);
+ ret = uvc_video_encode_data(video, buf, mem, len);
+
+ video->payload_size += ret;
+ len -= ret;
+
+ req->length = video->req_size - len;
+ req->zero = video->payload_size == video->max_payload_size;
+
+ if (buf->bytesused == video->queue.buf_used) {
+ video->queue.buf_used = 0;
+ buf->state = UVC_BUF_STATE_DONE;
+ uvcg_queue_next_buffer(&video->queue, buf);
+ video->fid ^= UVC_STREAM_FID;
+
+ video->payload_size = 0;
+ }
+
+ if (video->payload_size == video->max_payload_size ||
+ buf->bytesused == video->queue.buf_used)
+ video->payload_size = 0;
+}
+
+static void
+uvc_video_encode_isoc(struct usb_request *req, struct uvc_video *video,
+ struct uvc_buffer *buf)
+{
+ void *mem = req->buf;
+ int len = video->req_size;
+ int ret;
+
+ /* Add the header. */
+ ret = uvc_video_encode_header(video, buf, mem, len);
+ mem += ret;
+ len -= ret;
+
+ /* Process video data. */
+ ret = uvc_video_encode_data(video, buf, mem, len);
+ len -= ret;
+
+ req->length = video->req_size - len;
+
+ if (buf->bytesused == video->queue.buf_used) {
+ video->queue.buf_used = 0;
+ buf->state = UVC_BUF_STATE_DONE;
+ uvcg_queue_next_buffer(&video->queue, buf);
+ video->fid ^= UVC_STREAM_FID;
+ }
+}
+
+/* --------------------------------------------------------------------------
+ * Request handling
+ */
+
+/*
+ * I somehow feel that synchronisation won't be easy to achieve here. We have
+ * three events that control USB requests submission:
+ *
+ * - USB request completion: the completion handler will resubmit the request
+ * if a video buffer is available.
+ *
+ * - USB interface setting selection: in response to a SET_INTERFACE request,
+ * the handler will start streaming if a video buffer is available and if
+ * video is not currently streaming.
+ *
+ * - V4L2 buffer queueing: the driver will start streaming if video is not
+ * currently streaming.
+ *
+ * Race conditions between those 3 events might lead to deadlocks or other
+ * nasty side effects.
+ *
+ * The "video currently streaming" condition can't be detected by the irqqueue
+ * being empty, as a request can still be in flight. A separate "queue paused"
+ * flag is thus needed.
+ *
+ * The paused flag will be set when we try to retrieve the irqqueue head if the
+ * queue is empty, and cleared when we queue a buffer.
+ *
+ * The USB request completion handler will get the buffer at the irqqueue head
+ * under protection of the queue spinlock. If the queue is empty, the streaming
+ * paused flag will be set. Right after releasing the spinlock a userspace
+ * application can queue a buffer. The flag will then cleared, and the ioctl
+ * handler will restart the video stream.
+ */
+static void
+uvc_video_complete(struct usb_ep *ep, struct usb_request *req)
+{
+ struct uvc_video *video = req->context;
+ struct uvc_video_queue *queue = &video->queue;
+ struct uvc_buffer *buf;
+ unsigned long flags;
+ int ret;
+
+ switch (req->status) {
+ case 0:
+ break;
+
+ case -ESHUTDOWN: /* disconnect from host. */
+ printk(KERN_DEBUG "VS request cancelled.\n");
+ uvcg_queue_cancel(queue, 1);
+ goto requeue;
+
+ default:
+ printk(KERN_INFO "VS request completed with status %d.\n",
+ req->status);
+ uvcg_queue_cancel(queue, 0);
+ goto requeue;
+ }
+
+ spin_lock_irqsave(&video->queue.irqlock, flags);
+ buf = uvcg_queue_head(&video->queue);
+ if (buf == NULL) {
+ spin_unlock_irqrestore(&video->queue.irqlock, flags);
+ goto requeue;
+ }
+
+ video->encode(req, video, buf);
+
+ if ((ret = usb_ep_queue(ep, req, GFP_ATOMIC)) < 0) {
+ printk(KERN_INFO "Failed to queue request (%d).\n", ret);
+ usb_ep_set_halt(ep);
+ spin_unlock_irqrestore(&video->queue.irqlock, flags);
+ uvcg_queue_cancel(queue, 0);
+ goto requeue;
+ }
+ spin_unlock_irqrestore(&video->queue.irqlock, flags);
+
+ return;
+
+requeue:
+ spin_lock_irqsave(&video->req_lock, flags);
+ list_add_tail(&req->list, &video->req_free);
+ spin_unlock_irqrestore(&video->req_lock, flags);
+}
+
+static int
+uvc_video_free_requests(struct uvc_video *video)
+{
+ unsigned int i;
+
+ for (i = 0; i < UVC_NUM_REQUESTS; ++i) {
+ if (video->req[i]) {
+ usb_ep_free_request(video->ep, video->req[i]);
+ video->req[i] = NULL;
+ }
+
+ if (video->req_buffer[i]) {
+ kfree(video->req_buffer[i]);
+ video->req_buffer[i] = NULL;
+ }
+ }
+
+ INIT_LIST_HEAD(&video->req_free);
+ video->req_size = 0;
+ return 0;
+}
+
+static int
+uvc_video_alloc_requests(struct uvc_video *video)
+{
+ unsigned int req_size;
+ unsigned int i;
+ int ret = -ENOMEM;
+
+ BUG_ON(video->req_size);
+
+ req_size = video->ep->maxpacket
+ * max_t(unsigned int, video->ep->maxburst, 1)
+ * (video->ep->mult + 1);
+
+ for (i = 0; i < UVC_NUM_REQUESTS; ++i) {
+ video->req_buffer[i] = kmalloc(req_size, GFP_KERNEL);
+ if (video->req_buffer[i] == NULL)
+ goto error;
+
+ video->req[i] = usb_ep_alloc_request(video->ep, GFP_KERNEL);
+ if (video->req[i] == NULL)
+ goto error;
+
+ video->req[i]->buf = video->req_buffer[i];
+ video->req[i]->length = 0;
+ video->req[i]->complete = uvc_video_complete;
+ video->req[i]->context = video;
+
+ list_add_tail(&video->req[i]->list, &video->req_free);
+ }
+
+ video->req_size = req_size;
+
+ return 0;
+
+error:
+ uvc_video_free_requests(video);
+ return ret;
+}
+
+/* --------------------------------------------------------------------------
+ * Video streaming
+ */
+
+/*
+ * uvcg_video_pump - Pump video data into the USB requests
+ *
+ * This function fills the available USB requests (listed in req_free) with
+ * video data from the queued buffers.
+ */
+int uvcg_video_pump(struct uvc_video *video)
+{
+ struct uvc_video_queue *queue = &video->queue;
+ struct usb_request *req;
+ struct uvc_buffer *buf;
+ unsigned long flags;
+ int ret;
+
+ /* FIXME TODO Race between uvcg_video_pump and requests completion
+ * handler ???
+ */
+
+ while (1) {
+ /* Retrieve the first available USB request, protected by the
+ * request lock.
+ */
+ spin_lock_irqsave(&video->req_lock, flags);
+ if (list_empty(&video->req_free)) {
+ spin_unlock_irqrestore(&video->req_lock, flags);
+ return 0;
+ }
+ req = list_first_entry(&video->req_free, struct usb_request,
+ list);
+ list_del(&req->list);
+ spin_unlock_irqrestore(&video->req_lock, flags);
+
+ /* Retrieve the first available video buffer and fill the
+ * request, protected by the video queue irqlock.
+ */
+ spin_lock_irqsave(&queue->irqlock, flags);
+ buf = uvcg_queue_head(queue);
+ if (buf == NULL) {
+ spin_unlock_irqrestore(&queue->irqlock, flags);
+ break;
+ }
+
+ video->encode(req, video, buf);
+
+ /* Queue the USB request */
+ ret = usb_ep_queue(video->ep, req, GFP_ATOMIC);
+ if (ret < 0) {
+ printk(KERN_INFO "Failed to queue request (%d)\n", ret);
+ usb_ep_set_halt(video->ep);
+ spin_unlock_irqrestore(&queue->irqlock, flags);
+ uvcg_queue_cancel(queue, 0);
+ break;
+ }
+ spin_unlock_irqrestore(&queue->irqlock, flags);
+ }
+
+ spin_lock_irqsave(&video->req_lock, flags);
+ list_add_tail(&req->list, &video->req_free);
+ spin_unlock_irqrestore(&video->req_lock, flags);
+ return 0;
+}
+
+/*
+ * Enable or disable the video stream.
+ */
+int uvcg_video_enable(struct uvc_video *video, int enable)
+{
+ unsigned int i;
+ int ret;
+
+ if (video->ep == NULL) {
+ printk(KERN_INFO "Video enable failed, device is "
+ "uninitialized.\n");
+ return -ENODEV;
+ }
+
+ if (!enable) {
+ for (i = 0; i < UVC_NUM_REQUESTS; ++i)
+ if (video->req[i])
+ usb_ep_dequeue(video->ep, video->req[i]);
+
+ uvc_video_free_requests(video);
+ uvcg_queue_enable(&video->queue, 0);
+ return 0;
+ }
+
+ if ((ret = uvcg_queue_enable(&video->queue, 1)) < 0)
+ return ret;
+
+ if ((ret = uvc_video_alloc_requests(video)) < 0)
+ return ret;
+
+ if (video->max_payload_size) {
+ video->encode = uvc_video_encode_bulk;
+ video->payload_size = 0;
+ } else
+ video->encode = uvc_video_encode_isoc;
+
+ return uvcg_video_pump(video);
+}
+
+/*
+ * Initialize the UVC video stream.
+ */
+int uvcg_video_init(struct uvc_video *video)
+{
+ INIT_LIST_HEAD(&video->req_free);
+ spin_lock_init(&video->req_lock);
+
+ video->fcc = V4L2_PIX_FMT_YUYV;
+ video->bpp = 16;
+ video->width = 320;
+ video->height = 240;
+ video->imagesize = 320 * 240 * 2;
+
+ /* Initialize the video buffers queue. */
+ uvcg_queue_init(&video->queue, V4L2_BUF_TYPE_VIDEO_OUTPUT,
+ &video->mutex);
+ return 0;
+}
+
Code Review / kvmfornfv.git / blobdiff