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 #include "uvc_video.h"
  25
  26 /* --------------------------------------------------------------------------
  27  * Video codecs
  28  */
  29
  30 static int
  31 uvc_video_encode_header(struct uvc_video *video, struct uvc_buffer *buf,
  32                 u8 *data, int len)
  33 {
  34         data[0] = 2;
  35         data[1] = UVC_STREAM_EOH | video->fid;
  36
  37         if (buf->bytesused - video->queue.buf_used <= len - 2)
  38                 data[1] |= UVC_STREAM_EOF;
  39
  40         return 2;
  41 }
  42
  43 static int
  44 uvc_video_encode_data(struct uvc_video *video, struct uvc_buffer *buf,
  45                 u8 *data, int len)
  46 {
  47         struct uvc_video_queue *queue = &video->queue;
  48         unsigned int nbytes;
  49         void *mem;
  50
  51         /* Copy video data to the USB buffer. */
  52         mem = buf->mem + queue->buf_used;
  53         nbytes = min((unsigned int)len, buf->bytesused - queue->buf_used);
  54
  55         memcpy(data, mem, nbytes);
  56         queue->buf_used += nbytes;
  57
  58         return nbytes;
  59 }
  60
  61 static void
  62 uvc_video_encode_bulk(struct usb_request *req, struct uvc_video *video,
  63                 struct uvc_buffer *buf)
  64 {
  65         void *mem = req->buf;
  66         int len = video->req_size;
  67         int ret;
  68
  69         /* Add a header at the beginning of the payload. */
  70         if (video->payload_size == 0) {
  71                 ret = uvc_video_encode_header(video, buf, mem, len);
  72                 video->payload_size += ret;
  73                 mem += ret;
  74                 len -= ret;
  75         }
  76
  77         /* Process video data. */
  78         len = min((int)(video->max_payload_size - video->payload_size), len);
  79         ret = uvc_video_encode_data(video, buf, mem, len);
  80
  81         video->payload_size += ret;
  82         len -= ret;
  83
  84         req->length = video->req_size - len;
  85         req->zero = video->payload_size == video->max_payload_size;
  86
  87         if (buf->bytesused == video->queue.buf_used) {
  88                 video->queue.buf_used = 0;
  89                 buf->state = UVC_BUF_STATE_DONE;
  90                 uvcg_queue_next_buffer(&video->queue, buf);
  91                 video->fid ^= UVC_STREAM_FID;
  92
  93                 video->payload_size = 0;
  94         }
  95
  96         if (video->payload_size == video->max_payload_size ||
  97             buf->bytesused == video->queue.buf_used)
  98                 video->payload_size = 0;
  99 }
 100
 101 static void
 102 uvc_video_encode_isoc(struct usb_request *req, struct uvc_video *video,
 103                 struct uvc_buffer *buf)
 104 {
 105         void *mem = req->buf;
 106         int len = video->req_size;
 107         int ret;
 108
 109         /* Add the header. */
 110         ret = uvc_video_encode_header(video, buf, mem, len);
 111         mem += ret;
 112         len -= ret;
 113
 114         /* Process video data. */
 115         ret = uvc_video_encode_data(video, buf, mem, len);
 116         len -= ret;
 117
 118         req->length = video->req_size - len;
 119
 120         if (buf->bytesused == video->queue.buf_used) {
 121                 video->queue.buf_used = 0;
 122                 buf->state = UVC_BUF_STATE_DONE;
 123                 uvcg_queue_next_buffer(&video->queue, buf);
 124                 video->fid ^= UVC_STREAM_FID;
 125         }
 126 }
 127
 128 /* --------------------------------------------------------------------------
 129  * Request handling
 130  */
 131
 132 /*
 133  * I somehow feel that synchronisation won't be easy to achieve here. We have
 134  * three events that control USB requests submission:
 135  *
 136  * - USB request completion: the completion handler will resubmit the request
 137  *   if a video buffer is available.
 138  *
 139  * - USB interface setting selection: in response to a SET_INTERFACE request,
 140  *   the handler will start streaming if a video buffer is available and if
 141  *   video is not currently streaming.
 142  *
 143  * - V4L2 buffer queueing: the driver will start streaming if video is not
 144  *   currently streaming.
 145  *
 146  * Race conditions between those 3 events might lead to deadlocks or other
 147  * nasty side effects.
 148  *
 149  * The "video currently streaming" condition can't be detected by the irqqueue
 150  * being empty, as a request can still be in flight. A separate "queue paused"
 151  * flag is thus needed.
 152  *
 153  * The paused flag will be set when we try to retrieve the irqqueue head if the
 154  * queue is empty, and cleared when we queue a buffer.
 155  *
 156  * The USB request completion handler will get the buffer at the irqqueue head
 157  * under protection of the queue spinlock. If the queue is empty, the streaming
 158  * paused flag will be set. Right after releasing the spinlock a userspace
 159  * application can queue a buffer. The flag will then cleared, and the ioctl
 160  * handler will restart the video stream.
 161  */
 162 static void
 163 uvc_video_complete(struct usb_ep *ep, struct usb_request *req)
 164 {
 165         struct uvc_video *video = req->context;
 166         struct uvc_video_queue *queue = &video->queue;
 167         struct uvc_buffer *buf;
 168         unsigned long flags;
 169         int ret;
 170
 171         switch (req->status) {
 172         case 0:
 173                 break;
 174
 175         case -ESHUTDOWN:        /* disconnect from host. */
 176                 printk(KERN_DEBUG "VS request cancelled.\n");
 177                 uvcg_queue_cancel(queue, 1);
 178                 goto requeue;
 179
 180         default:
 181                 printk(KERN_INFO "VS request completed with status %d.\n",
 182                         req->status);
 183                 uvcg_queue_cancel(queue, 0);
 184                 goto requeue;
 185         }
 186
 187         spin_lock_irqsave(&video->queue.irqlock, flags);
 188         buf = uvcg_queue_head(&video->queue);
 189         if (buf == NULL) {
 190                 spin_unlock_irqrestore(&video->queue.irqlock, flags);
 191                 goto requeue;
 192         }
 193
 194         video->encode(req, video, buf);
 195
 196         if ((ret = usb_ep_queue(ep, req, GFP_ATOMIC)) < 0) {
 197                 printk(KERN_INFO "Failed to queue request (%d).\n", ret);
 198                 usb_ep_set_halt(ep);
 199                 spin_unlock_irqrestore(&video->queue.irqlock, flags);
 200                 uvcg_queue_cancel(queue, 0);
 201                 goto requeue;
 202         }
 203         spin_unlock_irqrestore(&video->queue.irqlock, flags);
 204
 205         return;
 206
 207 requeue:
 208         spin_lock_irqsave(&video->req_lock, flags);
 209         list_add_tail(&req->list, &video->req_free);
 210         spin_unlock_irqrestore(&video->req_lock, flags);
 211 }
 212
 213 static int
 214 uvc_video_free_requests(struct uvc_video *video)
 215 {
 216         unsigned int i;
 217
 218         for (i = 0; i < UVC_NUM_REQUESTS; ++i) {
 219                 if (video->req[i]) {
 220                         usb_ep_free_request(video->ep, video->req[i]);
 221                         video->req[i] = NULL;
 222                 }
 223
 224                 if (video->req_buffer[i]) {
 225                         kfree(video->req_buffer[i]);
 226                         video->req_buffer[i] = NULL;
 227                 }
 228         }
 229
 230         INIT_LIST_HEAD(&video->req_free);
 231         video->req_size = 0;
 232         return 0;
 233 }
 234
 235 static int
 236 uvc_video_alloc_requests(struct uvc_video *video)
 237 {
 238         unsigned int req_size;
 239         unsigned int i;
 240         int ret = -ENOMEM;
 241
 242         BUG_ON(video->req_size);
 243
 244         req_size = video->ep->maxpacket
 245                  * max_t(unsigned int, video->ep->maxburst, 1)
 246                  * (video->ep->mult);
 247
 248         for (i = 0; i < UVC_NUM_REQUESTS; ++i) {
 249                 video->req_buffer[i] = kmalloc(req_size, GFP_KERNEL);
 250                 if (video->req_buffer[i] == NULL)
 251                         goto error;
 252
 253                 video->req[i] = usb_ep_alloc_request(video->ep, GFP_KERNEL);
 254                 if (video->req[i] == NULL)
 255                         goto error;
 256
 257                 video->req[i]->buf = video->req_buffer[i];
 258                 video->req[i]->length = 0;
 259                 video->req[i]->complete = uvc_video_complete;
 260                 video->req[i]->context = video;
 261
 262                 list_add_tail(&video->req[i]->list, &video->req_free);
 263         }
 264
 265         video->req_size = req_size;
 266
 267         return 0;
 268
 269 error:
 270         uvc_video_free_requests(video);
 271         return ret;
 272 }
 273
 274 /* --------------------------------------------------------------------------
 275  * Video streaming
 276  */
 277
 278 /*
 279  * uvcg_video_pump - Pump video data into the USB requests
 280  *
 281  * This function fills the available USB requests (listed in req_free) with
 282  * video data from the queued buffers.
 283  */
 284 int uvcg_video_pump(struct uvc_video *video)
 285 {
 286         struct uvc_video_queue *queue = &video->queue;
 287         struct usb_request *req;
 288         struct uvc_buffer *buf;
 289         unsigned long flags;
 290         int ret;
 291
 292         /* FIXME TODO Race between uvcg_video_pump and requests completion
 293          * handler ???
 294          */
 295
 296         while (1) {
 297                 /* Retrieve the first available USB request, protected by the
 298                  * request lock.
 299                  */
 300                 spin_lock_irqsave(&video->req_lock, flags);
 301                 if (list_empty(&video->req_free)) {
 302                         spin_unlock_irqrestore(&video->req_lock, flags);
 303                         return 0;
 304                 }
 305                 req = list_first_entry(&video->req_free, struct usb_request,
 306                                         list);
 307                 list_del(&req->list);
 308                 spin_unlock_irqrestore(&video->req_lock, flags);
 309
 310                 /* Retrieve the first available video buffer and fill the
 311                  * request, protected by the video queue irqlock.
 312                  */
 313                 spin_lock_irqsave(&queue->irqlock, flags);
 314                 buf = uvcg_queue_head(queue);
 315                 if (buf == NULL) {
 316                         spin_unlock_irqrestore(&queue->irqlock, flags);
 317                         break;
 318                 }
 319
 320                 video->encode(req, video, buf);
 321
 322                 /* Queue the USB request */
 323                 ret = usb_ep_queue(video->ep, req, GFP_ATOMIC);
 324                 if (ret < 0) {
 325                         printk(KERN_INFO "Failed to queue request (%d)\n", ret);
 326                         usb_ep_set_halt(video->ep);
 327                         spin_unlock_irqrestore(&queue->irqlock, flags);
 328                         uvcg_queue_cancel(queue, 0);
 329                         break;
 330                 }
 331                 spin_unlock_irqrestore(&queue->irqlock, flags);
 332         }
 333
 334         spin_lock_irqsave(&video->req_lock, flags);
 335         list_add_tail(&req->list, &video->req_free);
 336         spin_unlock_irqrestore(&video->req_lock, flags);
 337         return 0;
 338 }
 339
 340 /*
 341  * Enable or disable the video stream.
 342  */
 343 int uvcg_video_enable(struct uvc_video *video, int enable)
 344 {
 345         unsigned int i;
 346         int ret;
 347
 348         if (video->ep == NULL) {
 349                 printk(KERN_INFO "Video enable failed, device is "
 350                         "uninitialized.\n");
 351                 return -ENODEV;
 352         }
 353
 354         if (!enable) {
 355                 for (i = 0; i < UVC_NUM_REQUESTS; ++i)
 356                         if (video->req[i])
 357                                 usb_ep_dequeue(video->ep, video->req[i]);
 358
 359                 uvc_video_free_requests(video);
 360                 uvcg_queue_enable(&video->queue, 0);
 361                 return 0;
 362         }
 363
 364         if ((ret = uvcg_queue_enable(&video->queue, 1)) < 0)
 365                 return ret;
 366
 367         if ((ret = uvc_video_alloc_requests(video)) < 0)
 368                 return ret;
 369
 370         if (video->max_payload_size) {
 371                 video->encode = uvc_video_encode_bulk;
 372                 video->payload_size = 0;
 373         } else
 374                 video->encode = uvc_video_encode_isoc;
 375
 376         return uvcg_video_pump(video);
 377 }
 378
 379 /*
 380  * Initialize the UVC video stream.
 381  */
 382 int uvcg_video_init(struct uvc_video *video)
 383 {
 384         INIT_LIST_HEAD(&video->req_free);
 385         spin_lock_init(&video->req_lock);
 386
 387         video->fcc = V4L2_PIX_FMT_YUYV;
 388         video->bpp = 16;
 389         video->width = 320;
 390         video->height = 240;
 391         video->imagesize = 320 * 240 * 2;
 392
 393         /* Initialize the video buffers queue. */
 394         uvcg_queue_init(&video->queue, V4L2_BUF_TYPE_VIDEO_OUTPUT,
 395                         &video->mutex);
 396         return 0;
 397 }
 398