1/*
2 *	uvc_video.c  --  USB Video Class Gadget driver
3 *
4 *	Copyright (C) 2009-2010
5 *	    Laurent Pinchart (laurent.pinchart@ideasonboard.com)
6 *
7 *	This program is free software; you can redistribute it and/or modify
8 *	it under the terms of the GNU General Public License as published by
9 *	the Free Software Foundation; either version 2 of the License, or
10 *	(at your option) any later version.
11 */
12
13#include <linux/kernel.h>
14#include <linux/device.h>
15#include <linux/errno.h>
16#include <linux/usb/ch9.h>
17#include <linux/usb/gadget.h>
18#include <linux/usb/video.h>
19
20#include <media/v4l2-dev.h>
21
22#include "uvc.h"
23#include "uvc_queue.h"
24
25/* --------------------------------------------------------------------------
26 * Video codecs
27 */
28
29static int
30uvc_video_encode_header(struct uvc_video *video, struct uvc_buffer *buf,
31		u8 *data, int len)
32{
33	data[0] = 2;
34	data[1] = UVC_STREAM_EOH | video->fid;
35
36	if (buf->bytesused - video->queue.buf_used <= len - 2)
37		data[1] |= UVC_STREAM_EOF;
38
39	return 2;
40}
41
42static int
43uvc_video_encode_data(struct uvc_video *video, struct uvc_buffer *buf,
44		u8 *data, int len)
45{
46	struct uvc_video_queue *queue = &video->queue;
47	unsigned int nbytes;
48	void *mem;
49
50	/* Copy video data to the USB buffer. */
51	mem = buf->mem + queue->buf_used;
52	nbytes = min((unsigned int)len, buf->bytesused - queue->buf_used);
53
54	memcpy(data, mem, nbytes);
55	queue->buf_used += nbytes;
56
57	return nbytes;
58}
59
60static void
61uvc_video_encode_bulk(struct usb_request *req, struct uvc_video *video,
62		struct uvc_buffer *buf)
63{
64	void *mem = req->buf;
65	int len = video->req_size;
66	int ret;
67
68	/* Add a header at the beginning of the payload. */
69	if (video->payload_size == 0) {
70		ret = uvc_video_encode_header(video, buf, mem, len);
71		video->payload_size += ret;
72		mem += ret;
73		len -= ret;
74	}
75
76	/* Process video data. */
77	len = min((int)(video->max_payload_size - video->payload_size), len);
78	ret = uvc_video_encode_data(video, buf, mem, len);
79
80	video->payload_size += ret;
81	len -= ret;
82
83	req->length = video->req_size - len;
84	req->zero = video->payload_size == video->max_payload_size;
85
86	if (buf->bytesused == video->queue.buf_used) {
87		video->queue.buf_used = 0;
88		buf->state = UVC_BUF_STATE_DONE;
89		uvcg_queue_next_buffer(&video->queue, buf);
90		video->fid ^= UVC_STREAM_FID;
91
92		video->payload_size = 0;
93	}
94
95	if (video->payload_size == video->max_payload_size ||
96	    buf->bytesused == video->queue.buf_used)
97		video->payload_size = 0;
98}
99
100static void
101uvc_video_encode_isoc(struct usb_request *req, struct uvc_video *video,
102		struct uvc_buffer *buf)
103{
104	void *mem = req->buf;
105	int len = video->req_size;
106	int ret;
107
108	/* Add the header. */
109	ret = uvc_video_encode_header(video, buf, mem, len);
110	mem += ret;
111	len -= ret;
112
113	/* Process video data. */
114	ret = uvc_video_encode_data(video, buf, mem, len);
115	len -= ret;
116
117	req->length = video->req_size - len;
118
119	if (buf->bytesused == video->queue.buf_used) {
120		video->queue.buf_used = 0;
121		buf->state = UVC_BUF_STATE_DONE;
122		uvcg_queue_next_buffer(&video->queue, buf);
123		video->fid ^= UVC_STREAM_FID;
124	}
125}
126
127/* --------------------------------------------------------------------------
128 * Request handling
129 */
130
131/*
132 * I somehow feel that synchronisation won't be easy to achieve here. We have
133 * three events that control USB requests submission:
134 *
135 * - USB request completion: the completion handler will resubmit the request
136 *   if a video buffer is available.
137 *
138 * - USB interface setting selection: in response to a SET_INTERFACE request,
139 *   the handler will start streaming if a video buffer is available and if
140 *   video is not currently streaming.
141 *
142 * - V4L2 buffer queueing: the driver will start streaming if video is not
143 *   currently streaming.
144 *
145 * Race conditions between those 3 events might lead to deadlocks or other
146 * nasty side effects.
147 *
148 * The "video currently streaming" condition can't be detected by the irqqueue
149 * being empty, as a request can still be in flight. A separate "queue paused"
150 * flag is thus needed.
151 *
152 * The paused flag will be set when we try to retrieve the irqqueue head if the
153 * queue is empty, and cleared when we queue a buffer.
154 *
155 * The USB request completion handler will get the buffer at the irqqueue head
156 * under protection of the queue spinlock. If the queue is empty, the streaming
157 * paused flag will be set. Right after releasing the spinlock a userspace
158 * application can queue a buffer. The flag will then cleared, and the ioctl
159 * handler will restart the video stream.
160 */
161static void
162uvc_video_complete(struct usb_ep *ep, struct usb_request *req)
163{
164	struct uvc_video *video = req->context;
165	struct uvc_video_queue *queue = &video->queue;
166	struct uvc_buffer *buf;
167	unsigned long flags;
168	int ret;
169
170	switch (req->status) {
171	case 0:
172		break;
173
174	case -ESHUTDOWN:	/* disconnect from host. */
175		printk(KERN_DEBUG "VS request cancelled.\n");
176		uvcg_queue_cancel(queue, 1);
177		goto requeue;
178
179	default:
180		printk(KERN_INFO "VS request completed with status %d.\n",
181			req->status);
182		uvcg_queue_cancel(queue, 0);
183		goto requeue;
184	}
185
186	spin_lock_irqsave(&video->queue.irqlock, flags);
187	buf = uvcg_queue_head(&video->queue);
188	if (buf == NULL) {
189		spin_unlock_irqrestore(&video->queue.irqlock, flags);
190		goto requeue;
191	}
192
193	video->encode(req, video, buf);
194
195	if ((ret = usb_ep_queue(ep, req, GFP_ATOMIC)) < 0) {
196		printk(KERN_INFO "Failed to queue request (%d).\n", ret);
197		usb_ep_set_halt(ep);
198		spin_unlock_irqrestore(&video->queue.irqlock, flags);
199		uvcg_queue_cancel(queue, 0);
200		goto requeue;
201	}
202	spin_unlock_irqrestore(&video->queue.irqlock, flags);
203
204	return;
205
206requeue:
207	spin_lock_irqsave(&video->req_lock, flags);
208	list_add_tail(&req->list, &video->req_free);
209	spin_unlock_irqrestore(&video->req_lock, flags);
210}
211
212static int
213uvc_video_free_requests(struct uvc_video *video)
214{
215	unsigned int i;
216
217	for (i = 0; i < UVC_NUM_REQUESTS; ++i) {
218		if (video->req[i]) {
219			usb_ep_free_request(video->ep, video->req[i]);
220			video->req[i] = NULL;
221		}
222
223		if (video->req_buffer[i]) {
224			kfree(video->req_buffer[i]);
225			video->req_buffer[i] = NULL;
226		}
227	}
228
229	INIT_LIST_HEAD(&video->req_free);
230	video->req_size = 0;
231	return 0;
232}
233
234static int
235uvc_video_alloc_requests(struct uvc_video *video)
236{
237	unsigned int req_size;
238	unsigned int i;
239	int ret = -ENOMEM;
240
241	BUG_ON(video->req_size);
242
243	req_size = video->ep->maxpacket
244		 * max_t(unsigned int, video->ep->maxburst, 1)
245		 * (video->ep->mult + 1);
246
247	for (i = 0; i < UVC_NUM_REQUESTS; ++i) {
248		video->req_buffer[i] = kmalloc(req_size, GFP_KERNEL);
249		if (video->req_buffer[i] == NULL)
250			goto error;
251
252		video->req[i] = usb_ep_alloc_request(video->ep, GFP_KERNEL);
253		if (video->req[i] == NULL)
254			goto error;
255
256		video->req[i]->buf = video->req_buffer[i];
257		video->req[i]->length = 0;
258		video->req[i]->complete = uvc_video_complete;
259		video->req[i]->context = video;
260
261		list_add_tail(&video->req[i]->list, &video->req_free);
262	}
263
264	video->req_size = req_size;
265
266	return 0;
267
268error:
269	uvc_video_free_requests(video);
270	return ret;
271}
272
273/* --------------------------------------------------------------------------
274 * Video streaming
275 */
276
277/*
278 * uvcg_video_pump - Pump video data into the USB requests
279 *
280 * This function fills the available USB requests (listed in req_free) with
281 * video data from the queued buffers.
282 */
283int uvcg_video_pump(struct uvc_video *video)
284{
285	struct uvc_video_queue *queue = &video->queue;
286	struct usb_request *req;
287	struct uvc_buffer *buf;
288	unsigned long flags;
289	int ret;
290
291	/* FIXME TODO Race between uvcg_video_pump and requests completion
292	 * handler ???
293	 */
294
295	while (1) {
296		/* Retrieve the first available USB request, protected by the
297		 * request lock.
298		 */
299		spin_lock_irqsave(&video->req_lock, flags);
300		if (list_empty(&video->req_free)) {
301			spin_unlock_irqrestore(&video->req_lock, flags);
302			return 0;
303		}
304		req = list_first_entry(&video->req_free, struct usb_request,
305					list);
306		list_del(&req->list);
307		spin_unlock_irqrestore(&video->req_lock, flags);
308
309		/* Retrieve the first available video buffer and fill the
310		 * request, protected by the video queue irqlock.
311		 */
312		spin_lock_irqsave(&queue->irqlock, flags);
313		buf = uvcg_queue_head(queue);
314		if (buf == NULL) {
315			spin_unlock_irqrestore(&queue->irqlock, flags);
316			break;
317		}
318
319		video->encode(req, video, buf);
320
321		/* Queue the USB request */
322		ret = usb_ep_queue(video->ep, req, GFP_ATOMIC);
323		if (ret < 0) {
324			printk(KERN_INFO "Failed to queue request (%d)\n", ret);
325			usb_ep_set_halt(video->ep);
326			spin_unlock_irqrestore(&queue->irqlock, flags);
327			uvcg_queue_cancel(queue, 0);
328			break;
329		}
330		spin_unlock_irqrestore(&queue->irqlock, flags);
331	}
332
333	spin_lock_irqsave(&video->req_lock, flags);
334	list_add_tail(&req->list, &video->req_free);
335	spin_unlock_irqrestore(&video->req_lock, flags);
336	return 0;
337}
338
339/*
340 * Enable or disable the video stream.
341 */
342int uvcg_video_enable(struct uvc_video *video, int enable)
343{
344	unsigned int i;
345	int ret;
346
347	if (video->ep == NULL) {
348		printk(KERN_INFO "Video enable failed, device is "
349			"uninitialized.\n");
350		return -ENODEV;
351	}
352
353	if (!enable) {
354		for (i = 0; i < UVC_NUM_REQUESTS; ++i)
355			if (video->req[i])
356				usb_ep_dequeue(video->ep, video->req[i]);
357
358		uvc_video_free_requests(video);
359		uvcg_queue_enable(&video->queue, 0);
360		return 0;
361	}
362
363	if ((ret = uvcg_queue_enable(&video->queue, 1)) < 0)
364		return ret;
365
366	if ((ret = uvc_video_alloc_requests(video)) < 0)
367		return ret;
368
369	if (video->max_payload_size) {
370		video->encode = uvc_video_encode_bulk;
371		video->payload_size = 0;
372	} else
373		video->encode = uvc_video_encode_isoc;
374
375	return uvcg_video_pump(video);
376}
377
378/*
379 * Initialize the UVC video stream.
380 */
381int uvcg_video_init(struct uvc_video *video)
382{
383	INIT_LIST_HEAD(&video->req_free);
384	spin_lock_init(&video->req_lock);
385
386	video->fcc = V4L2_PIX_FMT_YUYV;
387	video->bpp = 16;
388	video->width = 320;
389	video->height = 240;
390	video->imagesize = 320 * 240 * 2;
391
392	/* Initialize the video buffers queue. */
393	uvcg_queue_init(&video->queue, V4L2_BUF_TYPE_VIDEO_OUTPUT);
394	return 0;
395}
396
397