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 uvcg_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,
45 			   unsigned int *nbuffers, unsigned int *nplanes,
46 			   unsigned int sizes[], struct device *alloc_devs[])
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 vb2_v4l2_buffer *vbuf = to_vb2_v4l2_buffer(vb);
65 	struct uvc_buffer *buf = container_of(vbuf, struct uvc_buffer, buf);
66 
67 	if (vb->type == V4L2_BUF_TYPE_VIDEO_OUTPUT &&
68 	    vb2_get_plane_payload(vb, 0) > vb2_plane_size(vb, 0)) {
69 		uvc_trace(UVC_TRACE_CAPTURE, "[E] Bytes used out of bounds.\n");
70 		return -EINVAL;
71 	}
72 
73 	if (unlikely(queue->flags & UVC_QUEUE_DISCONNECTED))
74 		return -ENODEV;
75 
76 	buf->state = UVC_BUF_STATE_QUEUED;
77 	buf->mem = vb2_plane_vaddr(vb, 0);
78 	buf->length = vb2_plane_size(vb, 0);
79 	if (vb->type == V4L2_BUF_TYPE_VIDEO_CAPTURE)
80 		buf->bytesused = 0;
81 	else
82 		buf->bytesused = vb2_get_plane_payload(vb, 0);
83 
84 	return 0;
85 }
86 
87 static void uvc_buffer_queue(struct vb2_buffer *vb)
88 {
89 	struct uvc_video_queue *queue = vb2_get_drv_priv(vb->vb2_queue);
90 	struct vb2_v4l2_buffer *vbuf = to_vb2_v4l2_buffer(vb);
91 	struct uvc_buffer *buf = container_of(vbuf, struct uvc_buffer, buf);
92 	unsigned long flags;
93 
94 	spin_lock_irqsave(&queue->irqlock, flags);
95 
96 	if (likely(!(queue->flags & UVC_QUEUE_DISCONNECTED))) {
97 		list_add_tail(&buf->queue, &queue->irqqueue);
98 	} else {
99 		/* If the device is disconnected return the buffer to userspace
100 		 * directly. The next QBUF call will fail with -ENODEV.
101 		 */
102 		buf->state = UVC_BUF_STATE_ERROR;
103 		vb2_buffer_done(vb, VB2_BUF_STATE_ERROR);
104 	}
105 
106 	spin_unlock_irqrestore(&queue->irqlock, flags);
107 }
108 
109 static struct vb2_ops uvc_queue_qops = {
110 	.queue_setup = uvc_queue_setup,
111 	.buf_prepare = uvc_buffer_prepare,
112 	.buf_queue = uvc_buffer_queue,
113 	.wait_prepare = vb2_ops_wait_prepare,
114 	.wait_finish = vb2_ops_wait_finish,
115 };
116 
117 int uvcg_queue_init(struct uvc_video_queue *queue, enum v4l2_buf_type type,
118 		    struct mutex *lock)
119 {
120 	int ret;
121 
122 	queue->queue.type = type;
123 	queue->queue.io_modes = VB2_MMAP | VB2_USERPTR | VB2_DMABUF;
124 	queue->queue.drv_priv = queue;
125 	queue->queue.buf_struct_size = sizeof(struct uvc_buffer);
126 	queue->queue.ops = &uvc_queue_qops;
127 	queue->queue.lock = lock;
128 	queue->queue.mem_ops = &vb2_vmalloc_memops;
129 	queue->queue.timestamp_flags = V4L2_BUF_FLAG_TIMESTAMP_MONOTONIC
130 				     | V4L2_BUF_FLAG_TSTAMP_SRC_EOF;
131 	ret = vb2_queue_init(&queue->queue);
132 	if (ret)
133 		return ret;
134 
135 	spin_lock_init(&queue->irqlock);
136 	INIT_LIST_HEAD(&queue->irqqueue);
137 	queue->flags = 0;
138 
139 	return 0;
140 }
141 
142 /*
143  * Free the video buffers.
144  */
145 void uvcg_free_buffers(struct uvc_video_queue *queue)
146 {
147 	vb2_queue_release(&queue->queue);
148 }
149 
150 /*
151  * Allocate the video buffers.
152  */
153 int uvcg_alloc_buffers(struct uvc_video_queue *queue,
154 			      struct v4l2_requestbuffers *rb)
155 {
156 	int ret;
157 
158 	ret = vb2_reqbufs(&queue->queue, rb);
159 
160 	return ret ? ret : rb->count;
161 }
162 
163 int uvcg_query_buffer(struct uvc_video_queue *queue, struct v4l2_buffer *buf)
164 {
165 	return vb2_querybuf(&queue->queue, buf);
166 }
167 
168 int uvcg_queue_buffer(struct uvc_video_queue *queue, struct v4l2_buffer *buf)
169 {
170 	unsigned long flags;
171 	int ret;
172 
173 	ret = vb2_qbuf(&queue->queue, buf);
174 	if (ret < 0)
175 		return ret;
176 
177 	spin_lock_irqsave(&queue->irqlock, flags);
178 	ret = (queue->flags & UVC_QUEUE_PAUSED) != 0;
179 	queue->flags &= ~UVC_QUEUE_PAUSED;
180 	spin_unlock_irqrestore(&queue->irqlock, flags);
181 	return ret;
182 }
183 
184 /*
185  * Dequeue a video buffer. If nonblocking is false, block until a buffer is
186  * available.
187  */
188 int uvcg_dequeue_buffer(struct uvc_video_queue *queue, struct v4l2_buffer *buf,
189 			int nonblocking)
190 {
191 	return vb2_dqbuf(&queue->queue, buf, nonblocking);
192 }
193 
194 /*
195  * Poll the video queue.
196  *
197  * This function implements video queue polling and is intended to be used by
198  * the device poll handler.
199  */
200 unsigned int uvcg_queue_poll(struct uvc_video_queue *queue, struct file *file,
201 			     poll_table *wait)
202 {
203 	return vb2_poll(&queue->queue, file, wait);
204 }
205 
206 int uvcg_queue_mmap(struct uvc_video_queue *queue, struct vm_area_struct *vma)
207 {
208 	return vb2_mmap(&queue->queue, vma);
209 }
210 
211 #ifndef CONFIG_MMU
212 /*
213  * Get unmapped area.
214  *
215  * NO-MMU arch need this function to make mmap() work correctly.
216  */
217 unsigned long uvcg_queue_get_unmapped_area(struct uvc_video_queue *queue,
218 					   unsigned long pgoff)
219 {
220 	return vb2_get_unmapped_area(&queue->queue, 0, 0, pgoff, 0);
221 }
222 #endif
223 
224 /*
225  * Cancel the video buffers queue.
226  *
227  * Cancelling the queue marks all buffers on the irq queue as erroneous,
228  * wakes them up and removes them from the queue.
229  *
230  * If the disconnect parameter is set, further calls to uvc_queue_buffer will
231  * fail with -ENODEV.
232  *
233  * This function acquires the irq spinlock and can be called from interrupt
234  * context.
235  */
236 void uvcg_queue_cancel(struct uvc_video_queue *queue, int disconnect)
237 {
238 	struct uvc_buffer *buf;
239 	unsigned long flags;
240 
241 	spin_lock_irqsave(&queue->irqlock, flags);
242 	while (!list_empty(&queue->irqqueue)) {
243 		buf = list_first_entry(&queue->irqqueue, struct uvc_buffer,
244 				       queue);
245 		list_del(&buf->queue);
246 		buf->state = UVC_BUF_STATE_ERROR;
247 		vb2_buffer_done(&buf->buf.vb2_buf, VB2_BUF_STATE_ERROR);
248 	}
249 	/* This must be protected by the irqlock spinlock to avoid race
250 	 * conditions between uvc_queue_buffer and the disconnection event that
251 	 * could result in an interruptible wait in uvc_dequeue_buffer. Do not
252 	 * blindly replace this logic by checking for the UVC_DEV_DISCONNECTED
253 	 * state outside the queue code.
254 	 */
255 	if (disconnect)
256 		queue->flags |= UVC_QUEUE_DISCONNECTED;
257 	spin_unlock_irqrestore(&queue->irqlock, flags);
258 }
259 
260 /*
261  * Enable or disable the video buffers queue.
262  *
263  * The queue must be enabled before starting video acquisition and must be
264  * disabled after stopping it. This ensures that the video buffers queue
265  * state can be properly initialized before buffers are accessed from the
266  * interrupt handler.
267  *
268  * Enabling the video queue initializes parameters (such as sequence number,
269  * sync pattern, ...). If the queue is already enabled, return -EBUSY.
270  *
271  * Disabling the video queue cancels the queue and removes all buffers from
272  * the main queue.
273  *
274  * This function can't be called from interrupt context. Use
275  * uvcg_queue_cancel() instead.
276  */
277 int uvcg_queue_enable(struct uvc_video_queue *queue, int enable)
278 {
279 	unsigned long flags;
280 	int ret = 0;
281 
282 	if (enable) {
283 		ret = vb2_streamon(&queue->queue, queue->queue.type);
284 		if (ret < 0)
285 			return ret;
286 
287 		queue->sequence = 0;
288 		queue->buf_used = 0;
289 	} else {
290 		ret = vb2_streamoff(&queue->queue, queue->queue.type);
291 		if (ret < 0)
292 			return ret;
293 
294 		spin_lock_irqsave(&queue->irqlock, flags);
295 		INIT_LIST_HEAD(&queue->irqqueue);
296 
297 		/*
298 		 * FIXME: We need to clear the DISCONNECTED flag to ensure that
299 		 * applications will be able to queue buffers for the next
300 		 * streaming run. However, clearing it here doesn't guarantee
301 		 * that the device will be reconnected in the meantime.
302 		 */
303 		queue->flags &= ~UVC_QUEUE_DISCONNECTED;
304 		spin_unlock_irqrestore(&queue->irqlock, flags);
305 	}
306 
307 	return ret;
308 }
309 
310 /* called with &queue_irqlock held.. */
311 struct uvc_buffer *uvcg_queue_next_buffer(struct uvc_video_queue *queue,
312 					  struct uvc_buffer *buf)
313 {
314 	struct uvc_buffer *nextbuf;
315 
316 	if ((queue->flags & UVC_QUEUE_DROP_INCOMPLETE) &&
317 	     buf->length != buf->bytesused) {
318 		buf->state = UVC_BUF_STATE_QUEUED;
319 		vb2_set_plane_payload(&buf->buf.vb2_buf, 0, 0);
320 		return buf;
321 	}
322 
323 	list_del(&buf->queue);
324 	if (!list_empty(&queue->irqqueue))
325 		nextbuf = list_first_entry(&queue->irqqueue, struct uvc_buffer,
326 					   queue);
327 	else
328 		nextbuf = NULL;
329 
330 	buf->buf.field = V4L2_FIELD_NONE;
331 	buf->buf.sequence = queue->sequence++;
332 	buf->buf.vb2_buf.timestamp = ktime_get_ns();
333 
334 	vb2_set_plane_payload(&buf->buf.vb2_buf, 0, buf->bytesused);
335 	vb2_buffer_done(&buf->buf.vb2_buf, VB2_BUF_STATE_DONE);
336 
337 	return nextbuf;
338 }
339 
340 struct uvc_buffer *uvcg_queue_head(struct uvc_video_queue *queue)
341 {
342 	struct uvc_buffer *buf = NULL;
343 
344 	if (!list_empty(&queue->irqqueue))
345 		buf = list_first_entry(&queue->irqqueue, struct uvc_buffer,
346 				       queue);
347 	else
348 		queue->flags |= UVC_QUEUE_PAUSED;
349 
350 	return buf;
351 }
352 
353