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