aboutsummaryrefslogtreecommitdiffstats
path: root/drivers/usb/gadget/uvc_video.c
blob: de8cbc46518dc2c45b19dfd743715f5449e5e6c8 (plain) (blame)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
/*
 *	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 <media/v4l2-dev.h>

#include "uvc.h"
#include "uvc_queue.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->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 = queue->mem + buf->buf.m.offset + queue->buf_used;
	nbytes = min((unsigned int)len, buf->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->buf.bytesused == video->queue.buf_used) {
		video->queue.buf_used = 0;
		buf->state = UVC_BUF_STATE_DONE;
		uvc_queue_next_buffer(&video->queue, buf);
		video->fid ^= UVC_STREAM_FID;

		video->payload_size = 0;
	}

	if (video->payload_size == video->max_payload_size ||
	    buf->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->buf.bytesused == video->queue.buf_used) {
		video->queue.buf_used = 0;
		buf->state = UVC_BUF_STATE_DONE;
		uvc_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_buffer *buf;
	unsigned long flags;
	int ret;

	switch (req->status) {
	case 0:
		break;

	case -ESHUTDOWN:
		printk(KERN_INFO "VS request cancelled.\n");
		goto requeue;

	default:
		printk(KERN_INFO "VS request completed with status %d.\n",
			req->status);
		goto requeue;
	}

	spin_lock_irqsave(&video->queue.irqlock, flags);
	buf = uvc_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);
		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 i;
	int ret = -ENOMEM;

	BUG_ON(video->req_size);

	for (i = 0; i < UVC_NUM_REQUESTS; ++i) {
		video->req_buffer[i] = kmalloc(video->ep->maxpacket, 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]->dma = DMA_ADDR_INVALID;
		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 = video->ep->maxpacket;
	return 0;

error:
	uvc_video_free_requests(video);
	return ret;
}

/* --------------------------------------------------------------------------
 * Video streaming
 */

/*
 * uvc_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
uvc_video_pump(struct uvc_video *video)
{
	struct usb_request *req;
	struct uvc_buffer *buf;
	unsigned long flags;
	int ret;

	/* FIXME TODO Race between uvc_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(&video->queue.irqlock, flags);
		buf = uvc_queue_head(&video->queue);
		if (buf == NULL) {
			spin_unlock_irqrestore(&video->queue.irqlock, flags);
			break;
		}

		video->encode(req, video, buf);

		/* Queue the USB request */
		if ((ret = usb_ep_queue(video->ep, req, GFP_KERNEL)) < 0) {
			printk(KERN_INFO "Failed to queue request (%d)\n", ret);
			usb_ep_set_halt(video->ep);
			spin_unlock_irqrestore(&video->queue.irqlock, flags);
			break;
		}
		spin_unlock_irqrestore(&video->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
uvc_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)
			usb_ep_dequeue(video->ep, video->req[i]);

		uvc_video_free_requests(video);
		uvc_queue_enable(&video->queue, 0);
		return 0;
	}

	if ((ret = uvc_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 uvc_video_pump(video);
}

/*
 * Initialize the UVC video stream.
 */
int
uvc_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. */
	uvc_queue_init(&video->queue, V4L2_BUF_TYPE_VIDEO_OUTPUT);
	return 0;
}