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[karo-tx-linux.git] / drivers / usb / gadget / uvc_video.c
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
14 #include <linux/kernel.h>
15 #include <linux/device.h>
16 #include <linux/errno.h>
17 #include <linux/usb/ch9.h>
18 #include <linux/usb/gadget.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
29 static int
30 uvc_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->buf.bytesused - video->queue.buf_used <= len - 2)
37                 data[1] |= UVC_STREAM_EOF;
38
39         return 2;
40 }
41
42 static int
43 uvc_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 = queue->mem + buf->buf.m.offset + queue->buf_used;
52         nbytes = min((unsigned int)len, buf->buf.bytesused - queue->buf_used);
53
54         memcpy(data, mem, nbytes);
55         queue->buf_used += nbytes;
56
57         return nbytes;
58 }
59
60 static void
61 uvc_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->buf.bytesused == video->queue.buf_used) {
87                 video->queue.buf_used = 0;
88                 buf->state = UVC_BUF_STATE_DONE;
89                 uvc_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->buf.bytesused == video->queue.buf_used)
97                 video->payload_size = 0;
98 }
99
100 static void
101 uvc_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->buf.bytesused == video->queue.buf_used) {
120                 video->queue.buf_used = 0;
121                 buf->state = UVC_BUF_STATE_DONE;
122                 uvc_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  */
161 static void
162 uvc_video_complete(struct usb_ep *ep, struct usb_request *req)
163 {
164         struct uvc_video *video = req->context;
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:
174                 printk(KERN_INFO "VS request cancelled.\n");
175                 goto requeue;
176
177         default:
178                 printk(KERN_INFO "VS request completed with status %d.\n",
179                         req->status);
180                 goto requeue;
181         }
182
183         spin_lock_irqsave(&video->queue.irqlock, flags);
184         buf = uvc_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                 goto requeue;
197         }
198         spin_unlock_irqrestore(&video->queue.irqlock, flags);
199
200         return;
201
202 requeue:
203         spin_lock_irqsave(&video->req_lock, flags);
204         list_add_tail(&req->list, &video->req_free);
205         spin_unlock_irqrestore(&video->req_lock, flags);
206 }
207
208 static int
209 uvc_video_free_requests(struct uvc_video *video)
210 {
211         unsigned int i;
212
213         for (i = 0; i < UVC_NUM_REQUESTS; ++i) {
214                 if (video->req[i]) {
215                         usb_ep_free_request(video->ep, video->req[i]);
216                         video->req[i] = NULL;
217                 }
218
219                 if (video->req_buffer[i]) {
220                         kfree(video->req_buffer[i]);
221                         video->req_buffer[i] = NULL;
222                 }
223         }
224
225         INIT_LIST_HEAD(&video->req_free);
226         video->req_size = 0;
227         return 0;
228 }
229
230 static int
231 uvc_video_alloc_requests(struct uvc_video *video)
232 {
233         unsigned int i;
234         int ret = -ENOMEM;
235
236         BUG_ON(video->req_size);
237
238         for (i = 0; i < UVC_NUM_REQUESTS; ++i) {
239                 video->req_buffer[i] = kmalloc(video->ep->maxpacket, GFP_KERNEL);
240                 if (video->req_buffer[i] == NULL)
241                         goto error;
242
243                 video->req[i] = usb_ep_alloc_request(video->ep, GFP_KERNEL);
244                 if (video->req[i] == NULL)
245                         goto error;
246
247                 video->req[i]->buf = video->req_buffer[i];
248                 video->req[i]->length = 0;
249                 video->req[i]->dma = DMA_ADDR_INVALID;
250                 video->req[i]->complete = uvc_video_complete;
251                 video->req[i]->context = video;
252
253                 list_add_tail(&video->req[i]->list, &video->req_free);
254         }
255
256         video->req_size = video->ep->maxpacket;
257         return 0;
258
259 error:
260         uvc_video_free_requests(video);
261         return ret;
262 }
263
264 /* --------------------------------------------------------------------------
265  * Video streaming
266  */
267
268 /*
269  * uvc_video_pump - Pump video data into the USB requests
270  *
271  * This function fills the available USB requests (listed in req_free) with
272  * video data from the queued buffers.
273  */
274 static int
275 uvc_video_pump(struct uvc_video *video)
276 {
277         struct usb_request *req;
278         struct uvc_buffer *buf;
279         unsigned long flags;
280         int ret;
281
282         /* FIXME TODO Race between uvc_video_pump and requests completion
283          * handler ???
284          */
285
286         while (1) {
287                 /* Retrieve the first available USB request, protected by the
288                  * request lock.
289                  */
290                 spin_lock_irqsave(&video->req_lock, flags);
291                 if (list_empty(&video->req_free)) {
292                         spin_unlock_irqrestore(&video->req_lock, flags);
293                         return 0;
294                 }
295                 req = list_first_entry(&video->req_free, struct usb_request,
296                                         list);
297                 list_del(&req->list);
298                 spin_unlock_irqrestore(&video->req_lock, flags);
299
300                 /* Retrieve the first available video buffer and fill the
301                  * request, protected by the video queue irqlock.
302                  */
303                 spin_lock_irqsave(&video->queue.irqlock, flags);
304                 buf = uvc_queue_head(&video->queue);
305                 if (buf == NULL) {
306                         spin_unlock_irqrestore(&video->queue.irqlock, flags);
307                         break;
308                 }
309
310                 video->encode(req, video, buf);
311
312                 /* Queue the USB request */
313                 if ((ret = usb_ep_queue(video->ep, req, GFP_KERNEL)) < 0) {
314                         printk(KERN_INFO "Failed to queue request (%d)\n", ret);
315                         usb_ep_set_halt(video->ep);
316                         spin_unlock_irqrestore(&video->queue.irqlock, flags);
317                         break;
318                 }
319                 spin_unlock_irqrestore(&video->queue.irqlock, flags);
320         }
321
322         spin_lock_irqsave(&video->req_lock, flags);
323         list_add_tail(&req->list, &video->req_free);
324         spin_unlock_irqrestore(&video->req_lock, flags);
325         return 0;
326 }
327
328 /*
329  * Enable or disable the video stream.
330  */
331 static int
332 uvc_video_enable(struct uvc_video *video, int enable)
333 {
334         unsigned int i;
335         int ret;
336
337         if (video->ep == NULL) {
338                 printk(KERN_INFO "Video enable failed, device is "
339                         "uninitialized.\n");
340                 return -ENODEV;
341         }
342
343         if (!enable) {
344                 for (i = 0; i < UVC_NUM_REQUESTS; ++i)
345                         usb_ep_dequeue(video->ep, video->req[i]);
346
347                 uvc_video_free_requests(video);
348                 uvc_queue_enable(&video->queue, 0);
349                 return 0;
350         }
351
352         if ((ret = uvc_queue_enable(&video->queue, 1)) < 0)
353                 return ret;
354
355         if ((ret = uvc_video_alloc_requests(video)) < 0)
356                 return ret;
357
358         if (video->max_payload_size) {
359                 video->encode = uvc_video_encode_bulk;
360                 video->payload_size = 0;
361         } else
362                 video->encode = uvc_video_encode_isoc;
363
364         return uvc_video_pump(video);
365 }
366
367 /*
368  * Initialize the UVC video stream.
369  */
370 static int
371 uvc_video_init(struct uvc_video *video)
372 {
373         INIT_LIST_HEAD(&video->req_free);
374         spin_lock_init(&video->req_lock);
375
376         video->fcc = V4L2_PIX_FMT_YUYV;
377         video->bpp = 16;
378         video->width = 320;
379         video->height = 240;
380         video->imagesize = 320 * 240 * 2;
381
382         /* Initialize the video buffers queue. */
383         uvc_queue_init(&video->queue, V4L2_BUF_TYPE_VIDEO_OUTPUT);
384         return 0;
385 }
386