drivers/usb/gadget/function/uvc_video.c

   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 static int uvcg_video_ep_queue(struct uvc_video *video, struct usb_request *req)
 129 {
 130         int ret;
 131
 132         ret = usb_ep_queue(video->ep, req, GFP_ATOMIC);
 133         if (ret < 0) {
 134                 printk(KERN_INFO "Failed to queue request (%d).\n", ret);
 135                 /* Isochronous endpoints can't be halted. */
 136                 if (usb_endpoint_xfer_bulk(video->ep->desc))
 137                         usb_ep_set_halt(video->ep);
 138         }
 139
 140         return ret;
 141 }
 142
 143 /*
 144  * I somehow feel that synchronisation won't be easy to achieve here. We have
 145  * three events that control USB requests submission:
 146  *
 147  * - USB request completion: the completion handler will resubmit the request
 148  *   if a video buffer is available.
 149  *
 150  * - USB interface setting selection: in response to a SET_INTERFACE request,
 151  *   the handler will start streaming if a video buffer is available and if
 152  *   video is not currently streaming.
 153  *
 154  * - V4L2 buffer queueing: the driver will start streaming if video is not
 155  *   currently streaming.
 156  *
 157  * Race conditions between those 3 events might lead to deadlocks or other
 158  * nasty side effects.
 159  *
 160  * The "video currently streaming" condition can't be detected by the irqqueue
 161  * being empty, as a request can still be in flight. A separate "queue paused"
 162  * flag is thus needed.
 163  *
 164  * The paused flag will be set when we try to retrieve the irqqueue head if the
 165  * queue is empty, and cleared when we queue a buffer.
 166  *
 167  * The USB request completion handler will get the buffer at the irqqueue head
 168  * under protection of the queue spinlock. If the queue is empty, the streaming
 169  * paused flag will be set. Right after releasing the spinlock a userspace
 170  * application can queue a buffer. The flag will then cleared, and the ioctl
 171  * handler will restart the video stream.
 172  */
 173 static void
 174 uvc_video_complete(struct usb_ep *ep, struct usb_request *req)
 175 {
 176         struct uvc_video *video = req->context;
 177         struct uvc_video_queue *queue = &video->queue;
 178         struct uvc_buffer *buf;
 179         unsigned long flags;
 180         int ret;
 181
 182         switch (req->status) {
 183         case 0:
 184                 break;
 185
 186         case -ESHUTDOWN:        /* disconnect from host. */
 187                 printk(KERN_DEBUG "VS request cancelled.\n");
 188                 uvcg_queue_cancel(queue, 1);
 189                 goto requeue;
 190
 191         default:
 192                 printk(KERN_INFO "VS request completed with status %d.\n",
 193                         req->status);
 194                 uvcg_queue_cancel(queue, 0);
 195                 goto requeue;
 196         }
 197
 198         spin_lock_irqsave(&video->queue.irqlock, flags);
 199         buf = uvcg_queue_head(&video->queue);
 200         if (buf == NULL) {
 201                 spin_unlock_irqrestore(&video->queue.irqlock, flags);
 202                 goto requeue;
 203         }
 204
 205         video->encode(req, video, buf);
 206
 207         ret = uvcg_video_ep_queue(video, req);
 208         spin_unlock_irqrestore(&video->queue.irqlock, flags);
 209
 210         if (ret < 0) {
 211                 uvcg_queue_cancel(queue, 0);
 212                 goto requeue;
 213         }
 214
 215         return;
 216
 217 requeue:
 218         spin_lock_irqsave(&video->req_lock, flags);
 219         list_add_tail(&req->list, &video->req_free);
 220         spin_unlock_irqrestore(&video->req_lock, flags);
 221 }
 222
 223 static int
 224 uvc_video_free_requests(struct uvc_video *video)
 225 {
 226         unsigned int i;
 227
 228         for (i = 0; i < UVC_NUM_REQUESTS; ++i) {
 229                 if (video->req[i]) {
 230                         usb_ep_free_request(video->ep, video->req[i]);
 231                         video->req[i] = NULL;
 232                 }
 233
 234                 if (video->req_buffer[i]) {
 235                         kfree(video->req_buffer[i]);
 236                         video->req_buffer[i] = NULL;
 237                 }
 238         }
 239
 240         INIT_LIST_HEAD(&video->req_free);
 241         video->req_size = 0;
 242         return 0;
 243 }
 244
 245 static int
 246 uvc_video_alloc_requests(struct uvc_video *video)
 247 {
 248         unsigned int req_size;
 249         unsigned int i;
 250         int ret = -ENOMEM;
 251
 252         BUG_ON(video->req_size);
 253
 254         req_size = video->ep->maxpacket
 255                  * max_t(unsigned int, video->ep->maxburst, 1)
 256                  * (video->ep->mult);
 257
 258         for (i = 0; i < UVC_NUM_REQUESTS; ++i) {
 259                 video->req_buffer[i] = kmalloc(req_size, GFP_KERNEL);
 260                 if (video->req_buffer[i] == NULL)
 261                         goto error;
 262
 263                 video->req[i] = usb_ep_alloc_request(video->ep, GFP_KERNEL);
 264                 if (video->req[i] == NULL)
 265                         goto error;
 266
 267                 video->req[i]->buf = video->req_buffer[i];
 268                 video->req[i]->length = 0;
 269                 video->req[i]->complete = uvc_video_complete;
 270                 video->req[i]->context = video;
 271
 272                 list_add_tail(&video->req[i]->list, &video->req_free);
 273         }
 274
 275         video->req_size = req_size;
 276
 277         return 0;
 278
 279 error:
 280         uvc_video_free_requests(video);
 281         return ret;
 282 }
 283
 284 /* --------------------------------------------------------------------------
 285  * Video streaming
 286  */
 287
 288 /*
 289  * uvcg_video_pump - Pump video data into the USB requests
 290  *
 291  * This function fills the available USB requests (listed in req_free) with
 292  * video data from the queued buffers.
 293  */
 294 int uvcg_video_pump(struct uvc_video *video)
 295 {
 296         struct uvc_video_queue *queue = &video->queue;
 297         struct usb_request *req;
 298         struct uvc_buffer *buf;
 299         unsigned long flags;
 300         int ret;
 301
 302         /* FIXME TODO Race between uvcg_video_pump and requests completion
 303          * handler ???
 304          */
 305
 306         while (1) {
 307                 /* Retrieve the first available USB request, protected by the
 308                  * request lock.
 309                  */
 310                 spin_lock_irqsave(&video->req_lock, flags);
 311                 if (list_empty(&video->req_free)) {
 312                         spin_unlock_irqrestore(&video->req_lock, flags);
 313                         return 0;
 314                 }
 315                 req = list_first_entry(&video->req_free, struct usb_request,
 316                                         list);
 317                 list_del(&req->list);
 318                 spin_unlock_irqrestore(&video->req_lock, flags);
 319
 320                 /* Retrieve the first available video buffer and fill the
 321                  * request, protected by the video queue irqlock.
 322                  */
 323                 spin_lock_irqsave(&queue->irqlock, flags);
 324                 buf = uvcg_queue_head(queue);
 325                 if (buf == NULL) {
 326                         spin_unlock_irqrestore(&queue->irqlock, flags);
 327                         break;
 328                 }
 329
 330                 video->encode(req, video, buf);
 331
 332                 /* Queue the USB request */
 333                 ret = uvcg_video_ep_queue(video, req);
 334                 spin_unlock_irqrestore(&queue->irqlock, flags);
 335
 336                 if (ret < 0) {
 337                         uvcg_queue_cancel(queue, 0);
 338                         break;
 339                 }
 340         }
 341
 342         spin_lock_irqsave(&video->req_lock, flags);
 343         list_add_tail(&req->list, &video->req_free);
 344         spin_unlock_irqrestore(&video->req_lock, flags);
 345         return 0;
 346 }
 347
 348 /*
 349  * Enable or disable the video stream.
 350  */
 351 int uvcg_video_enable(struct uvc_video *video, int enable)
 352 {
 353         unsigned int i;
 354         int ret;
 355
 356         if (video->ep == NULL) {
 357                 printk(KERN_INFO "Video enable failed, device is "
 358                         "uninitialized.\n");
 359                 return -ENODEV;
 360         }
 361
 362         if (!enable) {
 363                 for (i = 0; i < UVC_NUM_REQUESTS; ++i)
 364                         if (video->req[i])
 365                                 usb_ep_dequeue(video->ep, video->req[i]);
 366
 367                 uvc_video_free_requests(video);
 368                 uvcg_queue_enable(&video->queue, 0);
 369                 return 0;
 370         }
 371
 372         if ((ret = uvcg_queue_enable(&video->queue, 1)) < 0)
 373                 return ret;
 374
 375         if ((ret = uvc_video_alloc_requests(video)) < 0)
 376                 return ret;
 377
 378         if (video->max_payload_size) {
 379                 video->encode = uvc_video_encode_bulk;
 380                 video->payload_size = 0;
 381         } else
 382                 video->encode = uvc_video_encode_isoc;
 383
 384         return uvcg_video_pump(video);
 385 }
 386
 387 /*
 388  * Initialize the UVC video stream.
 389  */
 390 int uvcg_video_init(struct uvc_video *video)
 391 {
 392         INIT_LIST_HEAD(&video->req_free);
 393         spin_lock_init(&video->req_lock);
 394
 395         video->fcc = V4L2_PIX_FMT_YUYV;
 396         video->bpp = 16;
 397         video->width = 320;
 398         video->height = 240;
 399         video->imagesize = 320 * 240 * 2;
 400
 401         /* Initialize the video buffers queue. */
 402         uvcg_queue_init(&video->queue, V4L2_BUF_TYPE_VIDEO_OUTPUT,
 403                         &video->mutex);
 404         return 0;
 405 }
 406