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