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 #include "uvc_video.h"
25 
26 /* --------------------------------------------------------------------------
27  * Video codecs
28  */
29 
30 static int
31 uvc_video_encode_header(struct uvc_video *video, struct uvc_buffer *buf,
32 		u8 *data, int len)
33 {
34 	data[0] = 2;
35 	data[1] = UVC_STREAM_EOH | video->fid;
36 
37 	if (buf->bytesused - video->queue.buf_used <= len - 2)
38 		data[1] |= UVC_STREAM_EOF;
39 
40 	return 2;
41 }
42 
43 static int
44 uvc_video_encode_data(struct uvc_video *video, struct uvc_buffer *buf,
45 		u8 *data, int len)
46 {
47 	struct uvc_video_queue *queue = &video->queue;
48 	unsigned int nbytes;
49 	void *mem;
50 
51 	/* Copy video data to the USB buffer. */
52 	mem = buf->mem + queue->buf_used;
53 	nbytes = min((unsigned int)len, buf->bytesused - queue->buf_used);
54 
55 	memcpy(data, mem, nbytes);
56 	queue->buf_used += nbytes;
57 
58 	return nbytes;
59 }
60 
61 static void
62 uvc_video_encode_bulk(struct usb_request *req, struct uvc_video *video,
63 		struct uvc_buffer *buf)
64 {
65 	void *mem = req->buf;
66 	int len = video->req_size;
67 	int ret;
68 
69 	/* Add a header at the beginning of the payload. */
70 	if (video->payload_size == 0) {
71 		ret = uvc_video_encode_header(video, buf, mem, len);
72 		video->payload_size += ret;
73 		mem += ret;
74 		len -= ret;
75 	}
76 
77 	/* Process video data. */
78 	len = min((int)(video->max_payload_size - video->payload_size), len);
79 	ret = uvc_video_encode_data(video, buf, mem, len);
80 
81 	video->payload_size += ret;
82 	len -= ret;
83 
84 	req->length = video->req_size - len;
85 	req->zero = video->payload_size == video->max_payload_size;
86 
87 	if (buf->bytesused == video->queue.buf_used) {
88 		video->queue.buf_used = 0;
89 		buf->state = UVC_BUF_STATE_DONE;
90 		uvcg_queue_next_buffer(&video->queue, buf);
91 		video->fid ^= UVC_STREAM_FID;
92 
93 		video->payload_size = 0;
94 	}
95 
96 	if (video->payload_size == video->max_payload_size ||
97 	    buf->bytesused == video->queue.buf_used)
98 		video->payload_size = 0;
99 }
100 
101 static void
102 uvc_video_encode_isoc(struct usb_request *req, struct uvc_video *video,
103 		struct uvc_buffer *buf)
104 {
105 	void *mem = req->buf;
106 	int len = video->req_size;
107 	int ret;
108 
109 	/* Add the header. */
110 	ret = uvc_video_encode_header(video, buf, mem, len);
111 	mem += ret;
112 	len -= ret;
113 
114 	/* Process video data. */
115 	ret = uvc_video_encode_data(video, buf, mem, len);
116 	len -= ret;
117 
118 	req->length = video->req_size - len;
119 
120 	if (buf->bytesused == video->queue.buf_used) {
121 		video->queue.buf_used = 0;
122 		buf->state = UVC_BUF_STATE_DONE;
123 		uvcg_queue_next_buffer(&video->queue, buf);
124 		video->fid ^= UVC_STREAM_FID;
125 	}
126 }
127 
128 /* --------------------------------------------------------------------------
129  * Request handling
130  */
131 
132 /*
133  * I somehow feel that synchronisation won't be easy to achieve here. We have
134  * three events that control USB requests submission:
135  *
136  * - USB request completion: the completion handler will resubmit the request
137  *   if a video buffer is available.
138  *
139  * - USB interface setting selection: in response to a SET_INTERFACE request,
140  *   the handler will start streaming if a video buffer is available and if
141  *   video is not currently streaming.
142  *
143  * - V4L2 buffer queueing: the driver will start streaming if video is not
144  *   currently streaming.
145  *
146  * Race conditions between those 3 events might lead to deadlocks or other
147  * nasty side effects.
148  *
149  * The "video currently streaming" condition can't be detected by the irqqueue
150  * being empty, as a request can still be in flight. A separate "queue paused"
151  * flag is thus needed.
152  *
153  * The paused flag will be set when we try to retrieve the irqqueue head if the
154  * queue is empty, and cleared when we queue a buffer.
155  *
156  * The USB request completion handler will get the buffer at the irqqueue head
157  * under protection of the queue spinlock. If the queue is empty, the streaming
158  * paused flag will be set. Right after releasing the spinlock a userspace
159  * application can queue a buffer. The flag will then cleared, and the ioctl
160  * handler will restart the video stream.
161  */
162 static void
163 uvc_video_complete(struct usb_ep *ep, struct usb_request *req)
164 {
165 	struct uvc_video *video = req->context;
166 	struct uvc_video_queue *queue = &video->queue;
167 	struct uvc_buffer *buf;
168 	unsigned long flags;
169 	int ret;
170 
171 	switch (req->status) {
172 	case 0:
173 		break;
174 
175 	case -ESHUTDOWN:	/* disconnect from host. */
176 		printk(KERN_DEBUG "VS request cancelled.\n");
177 		uvcg_queue_cancel(queue, 1);
178 		goto requeue;
179 
180 	default:
181 		printk(KERN_INFO "VS request completed with status %d.\n",
182 			req->status);
183 		uvcg_queue_cancel(queue, 0);
184 		goto requeue;
185 	}
186 
187 	spin_lock_irqsave(&video->queue.irqlock, flags);
188 	buf = uvcg_queue_head(&video->queue);
189 	if (buf == NULL) {
190 		spin_unlock_irqrestore(&video->queue.irqlock, flags);
191 		goto requeue;
192 	}
193 
194 	video->encode(req, video, buf);
195 
196 	if ((ret = usb_ep_queue(ep, req, GFP_ATOMIC)) < 0) {
197 		printk(KERN_INFO "Failed to queue request (%d).\n", ret);
198 		usb_ep_set_halt(ep);
199 		spin_unlock_irqrestore(&video->queue.irqlock, flags);
200 		uvcg_queue_cancel(queue, 0);
201 		goto requeue;
202 	}
203 	spin_unlock_irqrestore(&video->queue.irqlock, flags);
204 
205 	return;
206 
207 requeue:
208 	spin_lock_irqsave(&video->req_lock, flags);
209 	list_add_tail(&req->list, &video->req_free);
210 	spin_unlock_irqrestore(&video->req_lock, flags);
211 }
212 
213 static int
214 uvc_video_free_requests(struct uvc_video *video)
215 {
216 	unsigned int i;
217 
218 	for (i = 0; i < UVC_NUM_REQUESTS; ++i) {
219 		if (video->req[i]) {
220 			usb_ep_free_request(video->ep, video->req[i]);
221 			video->req[i] = NULL;
222 		}
223 
224 		if (video->req_buffer[i]) {
225 			kfree(video->req_buffer[i]);
226 			video->req_buffer[i] = NULL;
227 		}
228 	}
229 
230 	INIT_LIST_HEAD(&video->req_free);
231 	video->req_size = 0;
232 	return 0;
233 }
234 
235 static int
236 uvc_video_alloc_requests(struct uvc_video *video)
237 {
238 	unsigned int req_size;
239 	unsigned int i;
240 	int ret = -ENOMEM;
241 
242 	BUG_ON(video->req_size);
243 
244 	req_size = video->ep->maxpacket
245 		 * max_t(unsigned int, video->ep->maxburst, 1)
246 		 * (video->ep->mult);
247 
248 	for (i = 0; i < UVC_NUM_REQUESTS; ++i) {
249 		video->req_buffer[i] = kmalloc(req_size, GFP_KERNEL);
250 		if (video->req_buffer[i] == NULL)
251 			goto error;
252 
253 		video->req[i] = usb_ep_alloc_request(video->ep, GFP_KERNEL);
254 		if (video->req[i] == NULL)
255 			goto error;
256 
257 		video->req[i]->buf = video->req_buffer[i];
258 		video->req[i]->length = 0;
259 		video->req[i]->complete = uvc_video_complete;
260 		video->req[i]->context = video;
261 
262 		list_add_tail(&video->req[i]->list, &video->req_free);
263 	}
264 
265 	video->req_size = req_size;
266 
267 	return 0;
268 
269 error:
270 	uvc_video_free_requests(video);
271 	return ret;
272 }
273 
274 /* --------------------------------------------------------------------------
275  * Video streaming
276  */
277 
278 /*
279  * uvcg_video_pump - Pump video data into the USB requests
280  *
281  * This function fills the available USB requests (listed in req_free) with
282  * video data from the queued buffers.
283  */
284 int uvcg_video_pump(struct uvc_video *video)
285 {
286 	struct uvc_video_queue *queue = &video->queue;
287 	struct usb_request *req;
288 	struct uvc_buffer *buf;
289 	unsigned long flags;
290 	int ret;
291 
292 	/* FIXME TODO Race between uvcg_video_pump and requests completion
293 	 * handler ???
294 	 */
295 
296 	while (1) {
297 		/* Retrieve the first available USB request, protected by the
298 		 * request lock.
299 		 */
300 		spin_lock_irqsave(&video->req_lock, flags);
301 		if (list_empty(&video->req_free)) {
302 			spin_unlock_irqrestore(&video->req_lock, flags);
303 			return 0;
304 		}
305 		req = list_first_entry(&video->req_free, struct usb_request,
306 					list);
307 		list_del(&req->list);
308 		spin_unlock_irqrestore(&video->req_lock, flags);
309 
310 		/* Retrieve the first available video buffer and fill the
311 		 * request, protected by the video queue irqlock.
312 		 */
313 		spin_lock_irqsave(&queue->irqlock, flags);
314 		buf = uvcg_queue_head(queue);
315 		if (buf == NULL) {
316 			spin_unlock_irqrestore(&queue->irqlock, flags);
317 			break;
318 		}
319 
320 		video->encode(req, video, buf);
321 
322 		/* Queue the USB request */
323 		ret = usb_ep_queue(video->ep, req, GFP_ATOMIC);
324 		if (ret < 0) {
325 			printk(KERN_INFO "Failed to queue request (%d)\n", ret);
326 			usb_ep_set_halt(video->ep);
327 			spin_unlock_irqrestore(&queue->irqlock, flags);
328 			uvcg_queue_cancel(queue, 0);
329 			break;
330 		}
331 		spin_unlock_irqrestore(&queue->irqlock, flags);
332 	}
333 
334 	spin_lock_irqsave(&video->req_lock, flags);
335 	list_add_tail(&req->list, &video->req_free);
336 	spin_unlock_irqrestore(&video->req_lock, flags);
337 	return 0;
338 }
339 
340 /*
341  * Enable or disable the video stream.
342  */
343 int uvcg_video_enable(struct uvc_video *video, int enable)
344 {
345 	unsigned int i;
346 	int ret;
347 
348 	if (video->ep == NULL) {
349 		printk(KERN_INFO "Video enable failed, device is "
350 			"uninitialized.\n");
351 		return -ENODEV;
352 	}
353 
354 	if (!enable) {
355 		for (i = 0; i < UVC_NUM_REQUESTS; ++i)
356 			if (video->req[i])
357 				usb_ep_dequeue(video->ep, video->req[i]);
358 
359 		uvc_video_free_requests(video);
360 		uvcg_queue_enable(&video->queue, 0);
361 		return 0;
362 	}
363 
364 	if ((ret = uvcg_queue_enable(&video->queue, 1)) < 0)
365 		return ret;
366 
367 	if ((ret = uvc_video_alloc_requests(video)) < 0)
368 		return ret;
369 
370 	if (video->max_payload_size) {
371 		video->encode = uvc_video_encode_bulk;
372 		video->payload_size = 0;
373 	} else
374 		video->encode = uvc_video_encode_isoc;
375 
376 	return uvcg_video_pump(video);
377 }
378 
379 /*
380  * Initialize the UVC video stream.
381  */
382 int uvcg_video_init(struct uvc_video *video)
383 {
384 	INIT_LIST_HEAD(&video->req_free);
385 	spin_lock_init(&video->req_lock);
386 
387 	video->fcc = V4L2_PIX_FMT_YUYV;
388 	video->bpp = 16;
389 	video->width = 320;
390 	video->height = 240;
391 	video->imagesize = 320 * 240 * 2;
392 
393 	/* Initialize the video buffers queue. */
394 	uvcg_queue_init(&video->queue, V4L2_BUF_TYPE_VIDEO_OUTPUT,
395 			&video->mutex);
396 	return 0;
397 }
398 
399