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