1 // SPDX-License-Identifier: GPL-2.0+
2 /*
3  *	uvc_video.c  --  USB Video Class Gadget driver
4  *
5  *	Copyright (C) 2009-2010
6  *	    Laurent Pinchart (laurent.pinchart@ideasonboard.com)
7  */
8 
9 #include <linux/kernel.h>
10 #include <linux/device.h>
11 #include <linux/errno.h>
12 #include <linux/usb/ch9.h>
13 #include <linux/usb/gadget.h>
14 #include <linux/usb/video.h>
15 
16 #include <media/v4l2-dev.h>
17 
18 #include "uvc.h"
19 #include "uvc_queue.h"
20 #include "uvc_video.h"
21 
22 /* --------------------------------------------------------------------------
23  * Video codecs
24  */
25 
26 static int
27 uvc_video_encode_header(struct uvc_video *video, struct uvc_buffer *buf,
28 		u8 *data, int len)
29 {
30 	data[0] = 2;
31 	data[1] = UVC_STREAM_EOH | video->fid;
32 
33 	if (buf->bytesused - video->queue.buf_used <= len - 2)
34 		data[1] |= UVC_STREAM_EOF;
35 
36 	return 2;
37 }
38 
39 static int
40 uvc_video_encode_data(struct uvc_video *video, struct uvc_buffer *buf,
41 		u8 *data, int len)
42 {
43 	struct uvc_video_queue *queue = &video->queue;
44 	unsigned int nbytes;
45 	void *mem;
46 
47 	/* Copy video data to the USB buffer. */
48 	mem = buf->mem + queue->buf_used;
49 	nbytes = min((unsigned int)len, buf->bytesused - queue->buf_used);
50 
51 	memcpy(data, mem, nbytes);
52 	queue->buf_used += nbytes;
53 
54 	return nbytes;
55 }
56 
57 static void
58 uvc_video_encode_bulk(struct usb_request *req, struct uvc_video *video,
59 		struct uvc_buffer *buf)
60 {
61 	void *mem = req->buf;
62 	int len = video->req_size;
63 	int ret;
64 
65 	/* Add a header at the beginning of the payload. */
66 	if (video->payload_size == 0) {
67 		ret = uvc_video_encode_header(video, buf, mem, len);
68 		video->payload_size += ret;
69 		mem += ret;
70 		len -= ret;
71 	}
72 
73 	/* Process video data. */
74 	len = min((int)(video->max_payload_size - video->payload_size), len);
75 	ret = uvc_video_encode_data(video, buf, mem, len);
76 
77 	video->payload_size += ret;
78 	len -= ret;
79 
80 	req->length = video->req_size - len;
81 	req->zero = video->payload_size == video->max_payload_size;
82 
83 	if (buf->bytesused == video->queue.buf_used) {
84 		video->queue.buf_used = 0;
85 		buf->state = UVC_BUF_STATE_DONE;
86 		uvcg_queue_next_buffer(&video->queue, buf);
87 		video->fid ^= UVC_STREAM_FID;
88 
89 		video->payload_size = 0;
90 	}
91 
92 	if (video->payload_size == video->max_payload_size ||
93 	    buf->bytesused == video->queue.buf_used)
94 		video->payload_size = 0;
95 }
96 
97 static void
98 uvc_video_encode_isoc(struct usb_request *req, struct uvc_video *video,
99 		struct uvc_buffer *buf)
100 {
101 	void *mem = req->buf;
102 	int len = video->req_size;
103 	int ret;
104 
105 	/* Add the header. */
106 	ret = uvc_video_encode_header(video, buf, mem, len);
107 	mem += ret;
108 	len -= ret;
109 
110 	/* Process video data. */
111 	ret = uvc_video_encode_data(video, buf, mem, len);
112 	len -= ret;
113 
114 	req->length = video->req_size - len;
115 
116 	if (buf->bytesused == video->queue.buf_used) {
117 		video->queue.buf_used = 0;
118 		buf->state = UVC_BUF_STATE_DONE;
119 		uvcg_queue_next_buffer(&video->queue, buf);
120 		video->fid ^= UVC_STREAM_FID;
121 	}
122 }
123 
124 /* --------------------------------------------------------------------------
125  * Request handling
126  */
127 
128 /*
129  * I somehow feel that synchronisation won't be easy to achieve here. We have
130  * three events that control USB requests submission:
131  *
132  * - USB request completion: the completion handler will resubmit the request
133  *   if a video buffer is available.
134  *
135  * - USB interface setting selection: in response to a SET_INTERFACE request,
136  *   the handler will start streaming if a video buffer is available and if
137  *   video is not currently streaming.
138  *
139  * - V4L2 buffer queueing: the driver will start streaming if video is not
140  *   currently streaming.
141  *
142  * Race conditions between those 3 events might lead to deadlocks or other
143  * nasty side effects.
144  *
145  * The "video currently streaming" condition can't be detected by the irqqueue
146  * being empty, as a request can still be in flight. A separate "queue paused"
147  * flag is thus needed.
148  *
149  * The paused flag will be set when we try to retrieve the irqqueue head if the
150  * queue is empty, and cleared when we queue a buffer.
151  *
152  * The USB request completion handler will get the buffer at the irqqueue head
153  * under protection of the queue spinlock. If the queue is empty, the streaming
154  * paused flag will be set. Right after releasing the spinlock a userspace
155  * application can queue a buffer. The flag will then cleared, and the ioctl
156  * handler will restart the video stream.
157  */
158 static void
159 uvc_video_complete(struct usb_ep *ep, struct usb_request *req)
160 {
161 	struct uvc_video *video = req->context;
162 	struct uvc_video_queue *queue = &video->queue;
163 	struct uvc_buffer *buf;
164 	unsigned long flags;
165 	int ret;
166 
167 	switch (req->status) {
168 	case 0:
169 		break;
170 
171 	case -ESHUTDOWN:	/* disconnect from host. */
172 		printk(KERN_DEBUG "VS request cancelled.\n");
173 		uvcg_queue_cancel(queue, 1);
174 		goto requeue;
175 
176 	default:
177 		printk(KERN_INFO "VS request completed with status %d.\n",
178 			req->status);
179 		uvcg_queue_cancel(queue, 0);
180 		goto requeue;
181 	}
182 
183 	spin_lock_irqsave(&video->queue.irqlock, flags);
184 	buf = uvcg_queue_head(&video->queue);
185 	if (buf == NULL) {
186 		spin_unlock_irqrestore(&video->queue.irqlock, flags);
187 		goto requeue;
188 	}
189 
190 	video->encode(req, video, buf);
191 
192 	if ((ret = usb_ep_queue(ep, req, GFP_ATOMIC)) < 0) {
193 		printk(KERN_INFO "Failed to queue request (%d).\n", ret);
194 		usb_ep_set_halt(ep);
195 		spin_unlock_irqrestore(&video->queue.irqlock, flags);
196 		uvcg_queue_cancel(queue, 0);
197 		goto requeue;
198 	}
199 	spin_unlock_irqrestore(&video->queue.irqlock, flags);
200 
201 	return;
202 
203 requeue:
204 	spin_lock_irqsave(&video->req_lock, flags);
205 	list_add_tail(&req->list, &video->req_free);
206 	spin_unlock_irqrestore(&video->req_lock, flags);
207 }
208 
209 static int
210 uvc_video_free_requests(struct uvc_video *video)
211 {
212 	unsigned int i;
213 
214 	for (i = 0; i < UVC_NUM_REQUESTS; ++i) {
215 		if (video->req[i]) {
216 			usb_ep_free_request(video->ep, video->req[i]);
217 			video->req[i] = NULL;
218 		}
219 
220 		if (video->req_buffer[i]) {
221 			kfree(video->req_buffer[i]);
222 			video->req_buffer[i] = NULL;
223 		}
224 	}
225 
226 	INIT_LIST_HEAD(&video->req_free);
227 	video->req_size = 0;
228 	return 0;
229 }
230 
231 static int
232 uvc_video_alloc_requests(struct uvc_video *video)
233 {
234 	unsigned int req_size;
235 	unsigned int i;
236 	int ret = -ENOMEM;
237 
238 	BUG_ON(video->req_size);
239 
240 	req_size = video->ep->maxpacket
241 		 * max_t(unsigned int, video->ep->maxburst, 1)
242 		 * (video->ep->mult);
243 
244 	for (i = 0; i < UVC_NUM_REQUESTS; ++i) {
245 		video->req_buffer[i] = kmalloc(req_size, GFP_KERNEL);
246 		if (video->req_buffer[i] == NULL)
247 			goto error;
248 
249 		video->req[i] = usb_ep_alloc_request(video->ep, GFP_KERNEL);
250 		if (video->req[i] == NULL)
251 			goto error;
252 
253 		video->req[i]->buf = video->req_buffer[i];
254 		video->req[i]->length = 0;
255 		video->req[i]->complete = uvc_video_complete;
256 		video->req[i]->context = video;
257 
258 		list_add_tail(&video->req[i]->list, &video->req_free);
259 	}
260 
261 	video->req_size = req_size;
262 
263 	return 0;
264 
265 error:
266 	uvc_video_free_requests(video);
267 	return ret;
268 }
269 
270 /* --------------------------------------------------------------------------
271  * Video streaming
272  */
273 
274 /*
275  * uvcg_video_pump - Pump video data into the USB requests
276  *
277  * This function fills the available USB requests (listed in req_free) with
278  * video data from the queued buffers.
279  */
280 int uvcg_video_pump(struct uvc_video *video)
281 {
282 	struct uvc_video_queue *queue = &video->queue;
283 	struct usb_request *req;
284 	struct uvc_buffer *buf;
285 	unsigned long flags;
286 	int ret;
287 
288 	/* FIXME TODO Race between uvcg_video_pump and requests completion
289 	 * handler ???
290 	 */
291 
292 	while (1) {
293 		/* Retrieve the first available USB request, protected by the
294 		 * request lock.
295 		 */
296 		spin_lock_irqsave(&video->req_lock, flags);
297 		if (list_empty(&video->req_free)) {
298 			spin_unlock_irqrestore(&video->req_lock, flags);
299 			return 0;
300 		}
301 		req = list_first_entry(&video->req_free, struct usb_request,
302 					list);
303 		list_del(&req->list);
304 		spin_unlock_irqrestore(&video->req_lock, flags);
305 
306 		/* Retrieve the first available video buffer and fill the
307 		 * request, protected by the video queue irqlock.
308 		 */
309 		spin_lock_irqsave(&queue->irqlock, flags);
310 		buf = uvcg_queue_head(queue);
311 		if (buf == NULL) {
312 			spin_unlock_irqrestore(&queue->irqlock, flags);
313 			break;
314 		}
315 
316 		video->encode(req, video, buf);
317 
318 		/* Queue the USB request */
319 		ret = usb_ep_queue(video->ep, req, GFP_ATOMIC);
320 		if (ret < 0) {
321 			printk(KERN_INFO "Failed to queue request (%d)\n", ret);
322 			usb_ep_set_halt(video->ep);
323 			spin_unlock_irqrestore(&queue->irqlock, flags);
324 			uvcg_queue_cancel(queue, 0);
325 			break;
326 		}
327 		spin_unlock_irqrestore(&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 int uvcg_video_enable(struct uvc_video *video, int enable)
340 {
341 	unsigned int i;
342 	int ret;
343 
344 	if (video->ep == NULL) {
345 		printk(KERN_INFO "Video enable failed, device is "
346 			"uninitialized.\n");
347 		return -ENODEV;
348 	}
349 
350 	if (!enable) {
351 		for (i = 0; i < UVC_NUM_REQUESTS; ++i)
352 			if (video->req[i])
353 				usb_ep_dequeue(video->ep, video->req[i]);
354 
355 		uvc_video_free_requests(video);
356 		uvcg_queue_enable(&video->queue, 0);
357 		return 0;
358 	}
359 
360 	if ((ret = uvcg_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 uvcg_video_pump(video);
373 }
374 
375 /*
376  * Initialize the UVC video stream.
377  */
378 int uvcg_video_init(struct uvc_video *video)
379 {
380 	INIT_LIST_HEAD(&video->req_free);
381 	spin_lock_init(&video->req_lock);
382 
383 	video->fcc = V4L2_PIX_FMT_YUYV;
384 	video->bpp = 16;
385 	video->width = 320;
386 	video->height = 240;
387 	video->imagesize = 320 * 240 * 2;
388 
389 	/* Initialize the video buffers queue. */
390 	uvcg_queue_init(&video->queue, V4L2_BUF_TYPE_VIDEO_OUTPUT,
391 			&video->mutex);
392 	return 0;
393 }
394 
395