1 /*
2  *	uvc_queue.c  --  USB Video Class driver - Buffers management
3  *
4  *	Copyright (C) 2005-2010
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/atomic.h>
14 #include <linux/kernel.h>
15 #include <linux/mm.h>
16 #include <linux/list.h>
17 #include <linux/module.h>
18 #include <linux/usb.h>
19 #include <linux/videodev2.h>
20 #include <linux/vmalloc.h>
21 #include <linux/wait.h>
22 
23 #include <media/v4l2-common.h>
24 #include <media/videobuf2-vmalloc.h>
25 
26 #include "uvc.h"
27 
28 /* ------------------------------------------------------------------------
29  * Video buffers queue management.
30  *
31  * Video queues is initialized by uvc_queue_init(). The function performs
32  * basic initialization of the uvc_video_queue struct and never fails.
33  *
34  * Video buffers are managed by videobuf2. The driver uses a mutex to protect
35  * the videobuf2 queue operations by serializing calls to videobuf2 and a
36  * spinlock to protect the IRQ queue that holds the buffers to be processed by
37  * the driver.
38  */
39 
40 /* -----------------------------------------------------------------------------
41  * videobuf2 queue operations
42  */
43 
44 static int uvc_queue_setup(struct vb2_queue *vq, const struct v4l2_format *fmt,
45 			   unsigned int *nbuffers, unsigned int *nplanes,
46 			   unsigned int sizes[], void *alloc_ctxs[])
47 {
48 	struct uvc_video_queue *queue = vb2_get_drv_priv(vq);
49 	struct uvc_video *video = container_of(queue, struct uvc_video, queue);
50 
51 	if (*nbuffers > UVC_MAX_VIDEO_BUFFERS)
52 		*nbuffers = UVC_MAX_VIDEO_BUFFERS;
53 
54 	*nplanes = 1;
55 
56 	sizes[0] = video->imagesize;
57 
58 	return 0;
59 }
60 
61 static int uvc_buffer_prepare(struct vb2_buffer *vb)
62 {
63 	struct uvc_video_queue *queue = vb2_get_drv_priv(vb->vb2_queue);
64 	struct uvc_buffer *buf = container_of(vb, struct uvc_buffer, buf);
65 
66 	if (vb->v4l2_buf.type == V4L2_BUF_TYPE_VIDEO_OUTPUT &&
67 	    vb2_get_plane_payload(vb, 0) > vb2_plane_size(vb, 0)) {
68 		uvc_trace(UVC_TRACE_CAPTURE, "[E] Bytes used out of bounds.\n");
69 		return -EINVAL;
70 	}
71 
72 	if (unlikely(queue->flags & UVC_QUEUE_DISCONNECTED))
73 		return -ENODEV;
74 
75 	buf->state = UVC_BUF_STATE_QUEUED;
76 	buf->mem = vb2_plane_vaddr(vb, 0);
77 	buf->length = vb2_plane_size(vb, 0);
78 	if (vb->v4l2_buf.type == V4L2_BUF_TYPE_VIDEO_CAPTURE)
79 		buf->bytesused = 0;
80 	else
81 		buf->bytesused = vb2_get_plane_payload(vb, 0);
82 
83 	return 0;
84 }
85 
86 static void uvc_buffer_queue(struct vb2_buffer *vb)
87 {
88 	struct uvc_video_queue *queue = vb2_get_drv_priv(vb->vb2_queue);
89 	struct uvc_buffer *buf = container_of(vb, struct uvc_buffer, buf);
90 	unsigned long flags;
91 
92 	spin_lock_irqsave(&queue->irqlock, flags);
93 
94 	if (likely(!(queue->flags & UVC_QUEUE_DISCONNECTED))) {
95 		list_add_tail(&buf->queue, &queue->irqqueue);
96 	} else {
97 		/* If the device is disconnected return the buffer to userspace
98 		 * directly. The next QBUF call will fail with -ENODEV.
99 		 */
100 		buf->state = UVC_BUF_STATE_ERROR;
101 		vb2_buffer_done(&buf->buf, VB2_BUF_STATE_ERROR);
102 	}
103 
104 	spin_unlock_irqrestore(&queue->irqlock, flags);
105 }
106 
107 static void uvc_wait_prepare(struct vb2_queue *vq)
108 {
109 	struct uvc_video_queue *queue = vb2_get_drv_priv(vq);
110 
111 	mutex_unlock(&queue->mutex);
112 }
113 
114 static void uvc_wait_finish(struct vb2_queue *vq)
115 {
116 	struct uvc_video_queue *queue = vb2_get_drv_priv(vq);
117 
118 	mutex_lock(&queue->mutex);
119 }
120 
121 static struct vb2_ops uvc_queue_qops = {
122 	.queue_setup = uvc_queue_setup,
123 	.buf_prepare = uvc_buffer_prepare,
124 	.buf_queue = uvc_buffer_queue,
125 	.wait_prepare = uvc_wait_prepare,
126 	.wait_finish = uvc_wait_finish,
127 };
128 
129 static int uvc_queue_init(struct uvc_video_queue *queue,
130 			  enum v4l2_buf_type type)
131 {
132 	int ret;
133 
134 	queue->queue.type = type;
135 	queue->queue.io_modes = VB2_MMAP | VB2_USERPTR;
136 	queue->queue.drv_priv = queue;
137 	queue->queue.buf_struct_size = sizeof(struct uvc_buffer);
138 	queue->queue.ops = &uvc_queue_qops;
139 	queue->queue.mem_ops = &vb2_vmalloc_memops;
140 	queue->queue.timestamp_flags = V4L2_BUF_FLAG_TIMESTAMP_MONOTONIC
141 				     | V4L2_BUF_FLAG_TSTAMP_SRC_EOF;
142 	ret = vb2_queue_init(&queue->queue);
143 	if (ret)
144 		return ret;
145 
146 	mutex_init(&queue->mutex);
147 	spin_lock_init(&queue->irqlock);
148 	INIT_LIST_HEAD(&queue->irqqueue);
149 	queue->flags = 0;
150 
151 	return 0;
152 }
153 
154 /*
155  * Free the video buffers.
156  */
157 static void uvc_free_buffers(struct uvc_video_queue *queue)
158 {
159 	mutex_lock(&queue->mutex);
160 	vb2_queue_release(&queue->queue);
161 	mutex_unlock(&queue->mutex);
162 }
163 
164 /*
165  * Allocate the video buffers.
166  */
167 static int uvc_alloc_buffers(struct uvc_video_queue *queue,
168 			     struct v4l2_requestbuffers *rb)
169 {
170 	int ret;
171 
172 	mutex_lock(&queue->mutex);
173 	ret = vb2_reqbufs(&queue->queue, rb);
174 	mutex_unlock(&queue->mutex);
175 
176 	return ret ? ret : rb->count;
177 }
178 
179 static int uvc_query_buffer(struct uvc_video_queue *queue,
180 			    struct v4l2_buffer *buf)
181 {
182 	int ret;
183 
184 	mutex_lock(&queue->mutex);
185 	ret = vb2_querybuf(&queue->queue, buf);
186 	mutex_unlock(&queue->mutex);
187 
188 	return ret;
189 }
190 
191 static int uvc_queue_buffer(struct uvc_video_queue *queue,
192 			    struct v4l2_buffer *buf)
193 {
194 	unsigned long flags;
195 	int ret;
196 
197 	mutex_lock(&queue->mutex);
198 	ret = vb2_qbuf(&queue->queue, buf);
199 	if (ret < 0)
200 		goto done;
201 
202 	spin_lock_irqsave(&queue->irqlock, flags);
203 	ret = (queue->flags & UVC_QUEUE_PAUSED) != 0;
204 	queue->flags &= ~UVC_QUEUE_PAUSED;
205 	spin_unlock_irqrestore(&queue->irqlock, flags);
206 
207 done:
208 	mutex_unlock(&queue->mutex);
209 	return ret;
210 }
211 
212 /*
213  * Dequeue a video buffer. If nonblocking is false, block until a buffer is
214  * available.
215  */
216 static int uvc_dequeue_buffer(struct uvc_video_queue *queue,
217 			      struct v4l2_buffer *buf, int nonblocking)
218 {
219 	int ret;
220 
221 	mutex_lock(&queue->mutex);
222 	ret = vb2_dqbuf(&queue->queue, buf, nonblocking);
223 	mutex_unlock(&queue->mutex);
224 
225 	return ret;
226 }
227 
228 /*
229  * Poll the video queue.
230  *
231  * This function implements video queue polling and is intended to be used by
232  * the device poll handler.
233  */
234 static unsigned int uvc_queue_poll(struct uvc_video_queue *queue,
235 				   struct file *file, poll_table *wait)
236 {
237 	unsigned int ret;
238 
239 	mutex_lock(&queue->mutex);
240 	ret = vb2_poll(&queue->queue, file, wait);
241 	mutex_unlock(&queue->mutex);
242 
243 	return ret;
244 }
245 
246 static int uvc_queue_mmap(struct uvc_video_queue *queue,
247 			  struct vm_area_struct *vma)
248 {
249 	int ret;
250 
251 	mutex_lock(&queue->mutex);
252 	ret = vb2_mmap(&queue->queue, vma);
253 	mutex_unlock(&queue->mutex);
254 
255 	return ret;
256 }
257 
258 #ifndef CONFIG_MMU
259 /*
260  * Get unmapped area.
261  *
262  * NO-MMU arch need this function to make mmap() work correctly.
263  */
264 static unsigned long uvc_queue_get_unmapped_area(struct uvc_video_queue *queue,
265 		unsigned long pgoff)
266 {
267 	unsigned long ret;
268 
269 	mutex_lock(&queue->mutex);
270 	ret = vb2_get_unmapped_area(&queue->queue, 0, 0, pgoff, 0);
271 	mutex_unlock(&queue->mutex);
272 	return ret;
273 }
274 #endif
275 
276 /*
277  * Cancel the video buffers queue.
278  *
279  * Cancelling the queue marks all buffers on the irq queue as erroneous,
280  * wakes them up and removes them from the queue.
281  *
282  * If the disconnect parameter is set, further calls to uvc_queue_buffer will
283  * fail with -ENODEV.
284  *
285  * This function acquires the irq spinlock and can be called from interrupt
286  * context.
287  */
288 static void uvc_queue_cancel(struct uvc_video_queue *queue, int disconnect)
289 {
290 	struct uvc_buffer *buf;
291 	unsigned long flags;
292 
293 	spin_lock_irqsave(&queue->irqlock, flags);
294 	while (!list_empty(&queue->irqqueue)) {
295 		buf = list_first_entry(&queue->irqqueue, struct uvc_buffer,
296 				       queue);
297 		list_del(&buf->queue);
298 		buf->state = UVC_BUF_STATE_ERROR;
299 		vb2_buffer_done(&buf->buf, VB2_BUF_STATE_ERROR);
300 	}
301 	/* This must be protected by the irqlock spinlock to avoid race
302 	 * conditions between uvc_queue_buffer and the disconnection event that
303 	 * could result in an interruptible wait in uvc_dequeue_buffer. Do not
304 	 * blindly replace this logic by checking for the UVC_DEV_DISCONNECTED
305 	 * state outside the queue code.
306 	 */
307 	if (disconnect)
308 		queue->flags |= UVC_QUEUE_DISCONNECTED;
309 	spin_unlock_irqrestore(&queue->irqlock, flags);
310 }
311 
312 /*
313  * Enable or disable the video buffers queue.
314  *
315  * The queue must be enabled before starting video acquisition and must be
316  * disabled after stopping it. This ensures that the video buffers queue
317  * state can be properly initialized before buffers are accessed from the
318  * interrupt handler.
319  *
320  * Enabling the video queue initializes parameters (such as sequence number,
321  * sync pattern, ...). If the queue is already enabled, return -EBUSY.
322  *
323  * Disabling the video queue cancels the queue and removes all buffers from
324  * the main queue.
325  *
326  * This function can't be called from interrupt context. Use
327  * uvc_queue_cancel() instead.
328  */
329 static int uvc_queue_enable(struct uvc_video_queue *queue, int enable)
330 {
331 	unsigned long flags;
332 	int ret = 0;
333 
334 	mutex_lock(&queue->mutex);
335 	if (enable) {
336 		ret = vb2_streamon(&queue->queue, queue->queue.type);
337 		if (ret < 0)
338 			goto done;
339 
340 		queue->sequence = 0;
341 		queue->buf_used = 0;
342 	} else {
343 		ret = vb2_streamoff(&queue->queue, queue->queue.type);
344 		if (ret < 0)
345 			goto done;
346 
347 		spin_lock_irqsave(&queue->irqlock, flags);
348 		INIT_LIST_HEAD(&queue->irqqueue);
349 
350 		/*
351 		 * FIXME: We need to clear the DISCONNECTED flag to ensure that
352 		 * applications will be able to queue buffers for the next
353 		 * streaming run. However, clearing it here doesn't guarantee
354 		 * that the device will be reconnected in the meantime.
355 		 */
356 		queue->flags &= ~UVC_QUEUE_DISCONNECTED;
357 		spin_unlock_irqrestore(&queue->irqlock, flags);
358 	}
359 
360 done:
361 	mutex_unlock(&queue->mutex);
362 	return ret;
363 }
364 
365 /* called with &queue_irqlock held.. */
366 static struct uvc_buffer *uvc_queue_next_buffer(struct uvc_video_queue *queue,
367 						struct uvc_buffer *buf)
368 {
369 	struct uvc_buffer *nextbuf;
370 
371 	if ((queue->flags & UVC_QUEUE_DROP_INCOMPLETE) &&
372 	     buf->length != buf->bytesused) {
373 		buf->state = UVC_BUF_STATE_QUEUED;
374 		vb2_set_plane_payload(&buf->buf, 0, 0);
375 		return buf;
376 	}
377 
378 	list_del(&buf->queue);
379 	if (!list_empty(&queue->irqqueue))
380 		nextbuf = list_first_entry(&queue->irqqueue, struct uvc_buffer,
381 					   queue);
382 	else
383 		nextbuf = NULL;
384 
385 	buf->buf.v4l2_buf.field = V4L2_FIELD_NONE;
386 	buf->buf.v4l2_buf.sequence = queue->sequence++;
387 	v4l2_get_timestamp(&buf->buf.v4l2_buf.timestamp);
388 
389 	vb2_set_plane_payload(&buf->buf, 0, buf->bytesused);
390 	vb2_buffer_done(&buf->buf, VB2_BUF_STATE_DONE);
391 
392 	return nextbuf;
393 }
394 
395 static struct uvc_buffer *uvc_queue_head(struct uvc_video_queue *queue)
396 {
397 	struct uvc_buffer *buf = NULL;
398 
399 	if (!list_empty(&queue->irqqueue))
400 		buf = list_first_entry(&queue->irqqueue, struct uvc_buffer,
401 				       queue);
402 	else
403 		queue->flags |= UVC_QUEUE_PAUSED;
404 
405 	return buf;
406 }
407 
408