drivers/usb/gadget/function/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 #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
  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->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 = buf->mem + queue->buf_used;
  52         nbytes = min((unsigned int)len, 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->bytesused == video->queue.buf_used) {
  87                 video->queue.buf_used = 0;
  88                 buf->state = UVC_BUF_STATE_DONE;
  89                 uvcg_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->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->bytesused == video->queue.buf_used) {
 120                 video->queue.buf_used = 0;
 121                 buf->state = UVC_BUF_STATE_DONE;
 122                 uvcg_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_video_queue *queue = &video->queue;
 166         struct uvc_buffer *buf;
 167         unsigned long flags;
 168         int ret;
 169
 170         switch (req->status) {
 171         case 0:
 172                 break;
 173
 174         case -ESHUTDOWN:        /* disconnect from host. */
 175                 printk(KERN_DEBUG "VS request cancelled.\n");
 176                 uvcg_queue_cancel(queue, 1);
 177                 goto requeue;
 178
 179         default:
 180                 printk(KERN_INFO "VS request completed with status %d.\n",
 181                         req->status);
 182                 uvcg_queue_cancel(queue, 0);
 183                 goto requeue;
 184         }
 185
 186         spin_lock_irqsave(&video->queue.irqlock, flags);
 187         buf = uvcg_queue_head(&video->queue);
 188         if (buf == NULL) {
 189                 spin_unlock_irqrestore(&video->queue.irqlock, flags);
 190                 goto requeue;
 191         }
 192
 193         video->encode(req, video, buf);
 194
 195         if ((ret = usb_ep_queue(ep, req, GFP_ATOMIC)) < 0) {
 196                 printk(KERN_INFO "Failed to queue request (%d).\n", ret);
 197                 usb_ep_set_halt(ep);
 198                 spin_unlock_irqrestore(&video->queue.irqlock, flags);
 199                 uvcg_queue_cancel(queue, 0);
 200                 goto requeue;
 201         }
 202         spin_unlock_irqrestore(&video->queue.irqlock, flags);
 203
 204         return;
 205
 206 requeue:
 207         spin_lock_irqsave(&video->req_lock, flags);
 208         list_add_tail(&req->list, &video->req_free);
 209         spin_unlock_irqrestore(&video->req_lock, flags);
 210 }
 211
 212 static int
 213 uvc_video_free_requests(struct uvc_video *video)
 214 {
 215         unsigned int i;
 216
 217         for (i = 0; i < UVC_NUM_REQUESTS; ++i) {
 218                 if (video->req[i]) {
 219                         usb_ep_free_request(video->ep, video->req[i]);
 220                         video->req[i] = NULL;
 221                 }
 222
 223                 if (video->req_buffer[i]) {
 224                         kfree(video->req_buffer[i]);
 225                         video->req_buffer[i] = NULL;
 226                 }
 227         }
 228
 229         INIT_LIST_HEAD(&video->req_free);
 230         video->req_size = 0;
 231         return 0;
 232 }
 233
 234 static int
 235 uvc_video_alloc_requests(struct uvc_video *video)
 236 {
 237         unsigned int req_size;
 238         unsigned int i;
 239         int ret = -ENOMEM;
 240
 241         BUG_ON(video->req_size);
 242
 243         req_size = video->ep->maxpacket
 244                  * max_t(unsigned int, video->ep->maxburst, 1)
 245                  * (video->ep->mult + 1);
 246
 247         for (i = 0; i < UVC_NUM_REQUESTS; ++i) {
 248                 video->req_buffer[i] = kmalloc(req_size, GFP_KERNEL);
 249                 if (video->req_buffer[i] == NULL)
 250                         goto error;
 251
 252                 video->req[i] = usb_ep_alloc_request(video->ep, GFP_KERNEL);
 253                 if (video->req[i] == NULL)
 254                         goto error;
 255
 256                 video->req[i]->buf = video->req_buffer[i];
 257                 video->req[i]->length = 0;
 258                 video->req[i]->complete = uvc_video_complete;
 259                 video->req[i]->context = video;
 260
 261                 list_add_tail(&video->req[i]->list, &video->req_free);
 262         }
 263
 264         video->req_size = req_size;
 265
 266         return 0;
 267
 268 error:
 269         uvc_video_free_requests(video);
 270         return ret;
 271 }
 272
 273 /* --------------------------------------------------------------------------
 274  * Video streaming
 275  */
 276
 277 /*
 278  * uvcg_video_pump - Pump video data into the USB requests
 279  *
 280  * This function fills the available USB requests (listed in req_free) with
 281  * video data from the queued buffers.
 282  */
 283 int uvcg_video_pump(struct uvc_video *video)
 284 {
 285         struct uvc_video_queue *queue = &video->queue;
 286         struct usb_request *req;
 287         struct uvc_buffer *buf;
 288         unsigned long flags;
 289         int ret;
 290
 291         /* FIXME TODO Race between uvcg_video_pump and requests completion
 292          * handler ???
 293          */
 294
 295         while (1) {
 296                 /* Retrieve the first available USB request, protected by the
 297                  * request lock.
 298                  */
 299                 spin_lock_irqsave(&video->req_lock, flags);
 300                 if (list_empty(&video->req_free)) {
 301                         spin_unlock_irqrestore(&video->req_lock, flags);
 302                         return 0;
 303                 }
 304                 req = list_first_entry(&video->req_free, struct usb_request,
 305                                         list);
 306                 list_del(&req->list);
 307                 spin_unlock_irqrestore(&video->req_lock, flags);
 308
 309                 /* Retrieve the first available video buffer and fill the
 310                  * request, protected by the video queue irqlock.
 311                  */
 312                 spin_lock_irqsave(&queue->irqlock, flags);
 313                 buf = uvcg_queue_head(queue);
 314                 if (buf == NULL) {
 315                         spin_unlock_irqrestore(&queue->irqlock, flags);
 316                         break;
 317                 }
 318
 319                 video->encode(req, video, buf);
 320
 321                 /* Queue the USB request */
 322                 ret = usb_ep_queue(video->ep, req, GFP_ATOMIC);
 323                 if (ret < 0) {
 324                         printk(KERN_INFO "Failed to queue request (%d)\n", ret);
 325                         usb_ep_set_halt(video->ep);
 326                         spin_unlock_irqrestore(&queue->irqlock, flags);
 327                         uvcg_queue_cancel(queue, 0);
 328                         break;
 329                 }
 330                 spin_unlock_irqrestore(&queue->irqlock, flags);
 331         }
 332
 333         spin_lock_irqsave(&video->req_lock, flags);
 334         list_add_tail(&req->list, &video->req_free);
 335         spin_unlock_irqrestore(&video->req_lock, flags);
 336         return 0;
 337 }
 338
 339 /*
 340  * Enable or disable the video stream.
 341  */
 342 int uvcg_video_enable(struct uvc_video *video, int enable)
 343 {
 344         unsigned int i;
 345         int ret;
 346
 347         if (video->ep == NULL) {
 348                 printk(KERN_INFO "Video enable failed, device is "
 349                         "uninitialized.\n");
 350                 return -ENODEV;
 351         }
 352
 353         if (!enable) {
 354                 for (i = 0; i < UVC_NUM_REQUESTS; ++i)
 355                         usb_ep_dequeue(video->ep, video->req[i]);
 356
 357                 uvc_video_free_requests(video);
 358                 uvcg_queue_enable(&video->queue, 0);
 359                 return 0;
 360         }
 361
 362         if ((ret = uvcg_queue_enable(&video->queue, 1)) < 0)
 363                 return ret;
 364
 365         if ((ret = uvc_video_alloc_requests(video)) < 0)
 366                 return ret;
 367
 368         if (video->max_payload_size) {
 369                 video->encode = uvc_video_encode_bulk;
 370                 video->payload_size = 0;
 371         } else
 372                 video->encode = uvc_video_encode_isoc;
 373
 374         return uvcg_video_pump(video);
 375 }
 376
 377 /*
 378  * Initialize the UVC video stream.
 379  */
 380 int uvcg_video_init(struct uvc_video *video)
 381 {
 382         INIT_LIST_HEAD(&video->req_free);
 383         spin_lock_init(&video->req_lock);
 384
 385         video->fcc = V4L2_PIX_FMT_YUYV;
 386         video->bpp = 16;
 387         video->width = 320;
 388         video->height = 240;
 389         video->imagesize = 320 * 240 * 2;
 390
 391         /* Initialize the video buffers queue. */
 392         uvcg_queue_init(&video->queue, V4L2_BUF_TYPE_VIDEO_OUTPUT);
 393         return 0;
 394 }
 395