aboutsummaryrefslogtreecommitdiffstats
path: root/drivers/media/video/v4l2-dev.c
blob: 88eeee1d8baf5a80c5c9161e1c3f1779e601fbb1 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
/*
 * Video capture interface for Linux version 2
 *
 *	A generic video device interface for the LINUX operating system
 *	using a set of device structures/vectors for low level operations.
 *
 *	This program is free software; you can redistribute it and/or
 *	modify it under the terms of the GNU General Public License
 *	as published by the Free Software Foundation; either version
 *	2 of the License, or (at your option) any later version.
 *
 * Authors:	Alan Cox, <alan@redhat.com> (version 1)
 *              Mauro Carvalho Chehab <mchehab@infradead.org> (version 2)
 *
 * Fixes:	20000516  Claudio Matsuoka <claudio@conectiva.com>
 *		- Added procfs support
 */

#include <linux/module.h>
#include <linux/types.h>
#include <linux/kernel.h>
#include <linux/mm.h>
#include <linux/string.h>
#include <linux/errno.h>
#include <linux/init.h>
#include <linux/kmod.h>
#include <linux/slab.h>
#include <linux/smp_lock.h>
#include <asm/uaccess.h>
#include <asm/system.h>

#include <media/v4l2-common.h>

#define VIDEO_NUM_DEVICES	256
#define VIDEO_NAME              "video4linux"

/*
 *	sysfs stuff
 */

static ssize_t show_index(struct device *cd,
			 struct device_attribute *attr, char *buf)
{
	struct video_device *vfd = container_of(cd, struct video_device, dev);
	return sprintf(buf, "%i\n", vfd->index);
}

static ssize_t show_name(struct device *cd,
			 struct device_attribute *attr, char *buf)
{
	struct video_device *vfd = container_of(cd, struct video_device, dev);
	return sprintf(buf, "%.*s\n", (int)sizeof(vfd->name), vfd->name);
}

static struct device_attribute video_device_attrs[] = {
	__ATTR(name, S_IRUGO, show_name, NULL),
	__ATTR(index, S_IRUGO, show_index, NULL),
	__ATTR_NULL
};

struct video_device *video_device_alloc(void)
{
	struct video_device *vfd;

	vfd = kzalloc(sizeof(*vfd), GFP_KERNEL);
	return vfd;
}
EXPORT_SYMBOL(video_device_alloc);

void video_device_release(struct video_device *vfd)
{
	kfree(vfd);
}
EXPORT_SYMBOL(video_device_release);

static void video_release(struct device *cd)
{
	struct video_device *vfd = container_of(cd, struct video_device, dev);

#if 1
	/* needed until all drivers are fixed */
	if (!vfd->release)
		return;
#endif
	vfd->release(vfd);
}

static struct class video_class = {
	.name = VIDEO_NAME,
	.dev_attrs = video_device_attrs,
	.dev_release = video_release,
};

/*
 *	Active devices
 */

static struct video_device *video_device[VIDEO_NUM_DEVICES];
static DEFINE_MUTEX(videodev_lock);

struct video_device *video_devdata(struct file *file)
{
	return video_device[iminor(file->f_path.dentry->d_inode)];
}
EXPORT_SYMBOL(video_devdata);

/*
 *	Open a video device - FIXME: Obsoleted
 */
static int video_open(struct inode *inode, struct file *file)
{
	unsigned int minor = iminor(inode);
	int err = 0;
	struct video_device *vfl;
	const struct file_operations *old_fops;

	if (minor >= VIDEO_NUM_DEVICES)
		return -ENODEV;
	lock_kernel();
	mutex_lock(&videodev_lock);
	vfl = video_device[minor];
	if (vfl == NULL) {
		mutex_unlock(&videodev_lock);
		request_module("char-major-%d-%d", VIDEO_MAJOR, minor);
		mutex_lock(&videodev_lock);
		vfl = video_device[minor];
		if (vfl == NULL) {
			mutex_unlock(&videodev_lock);
			unlock_kernel();
			return -ENODEV;
		}
	}
	old_fops = file->f_op;
	file->f_op = fops_get(vfl->fops);
	if (file->f_op->open)
		err = file->f_op->open(inode, file);
	if (err) {
		fops_put(file->f_op);
		file->f_op = fops_get(old_fops);
	}
	fops_put(old_fops);
	mutex_unlock(&videodev_lock);
	unlock_kernel();
	return err;
}

/*
 * open/release helper functions -- handle exclusive opens
 * Should be removed soon
 */
int video_exclusive_open(struct inode *inode, struct file *file)
{
	struct video_device *vfl = video_devdata(file);
	int retval = 0;

	mutex_lock(&vfl->lock);
	if (vfl->users)
		retval = -EBUSY;
	else
		vfl->users++;
	mutex_unlock(&vfl->lock);
	return retval;
}
EXPORT_SYMBOL(video_exclusive_open);

int video_exclusive_release(struct inode *inode, struct file *file)
{
	struct video_device *vfl = video_devdata(file);

	vfl->users--;
	return 0;
}
EXPORT_SYMBOL(video_exclusive_release);

/**
 * get_index - assign stream number based on parent device
 * @vdev: video_device to assign index number to, vdev->dev should be assigned
 * @num: -1 if auto assign, requested number otherwise
 *
 *
 * returns -ENFILE if num is already in use, a free index number if
 * successful.
 */
static int get_index(struct video_device *vdev, int num)
{
	u32 used = 0;
	const int max_index = sizeof(used) * 8 - 1;
	int i;

	/* Currently a single v4l driver instance cannot create more than
	   32 devices.
	   Increase to u64 or an array of u32 if more are needed. */
	if (num > max_index) {
		printk(KERN_ERR "videodev: %s num is too large\n", __func__);
		return -EINVAL;
	}

	for (i = 0; i < VIDEO_NUM_DEVICES; i++) {
		if (video_device[i] != NULL &&
		    video_device[i] != vdev &&
		    video_device[i]->parent == vdev->parent) {
			used |= 1 << video_device[i]->index;
		}
	}

	if (num >= 0) {
		if (used & (1 << num))
			return -ENFILE;
		return num;
	}

	i = ffz(used);
	return i > max_index ? -ENFILE : i;
}

static const struct file_operations video_fops;

int video_register_device(struct video_device *vfd, int type, int nr)
{
	return video_register_device_index(vfd, type, nr, -1);
}
EXPORT_SYMBOL(video_register_device);

/**
 *	video_register_device - register video4linux devices
 *	@vfd:  video device structure we want to register
 *	@type: type of device to register
 *	@nr:   which device number (0 == /dev/video0, 1 == /dev/video1, ...
 *             -1 == first free)
 *
 *	The registration code assigns minor numbers based on the type
 *	requested. -ENFILE is returned in all the device slots for this
 *	category are full. If not then the minor field is set and the
 *	driver initialize function is called (if non %NULL).
 *
 *	Zero is returned on success.
 *
 *	Valid types are
 *
 *	%VFL_TYPE_GRABBER - A frame grabber
 *
 *	%VFL_TYPE_VTX - A teletext device
 *
 *	%VFL_TYPE_VBI - Vertical blank data (undecoded)
 *
 *	%VFL_TYPE_RADIO - A radio card
 */

int video_register_device_index(struct video_device *vfd, int type, int nr,
					int index)
{
	int i = 0;
	int base;
	int end;
	int ret;
	char *name_base;

	switch (type) {
	case VFL_TYPE_GRABBER:
		base = MINOR_VFL_TYPE_GRABBER_MIN;
		end = MINOR_VFL_TYPE_GRABBER_MAX+1;
		name_base = "video";
		break;
	case VFL_TYPE_VTX:
		base = MINOR_VFL_TYPE_VTX_MIN;
		end = MINOR_VFL_TYPE_VTX_MAX+1;
		name_base = "vtx";
		break;
	case VFL_TYPE_VBI:
		base = MINOR_VFL_TYPE_VBI_MIN;
		end = MINOR_VFL_TYPE_VBI_MAX+1;
		name_base = "vbi";
		break;
	case VFL_TYPE_RADIO:
		base = MINOR_VFL_TYPE_RADIO_MIN;
		end = MINOR_VFL_TYPE_RADIO_MAX+1;
		name_base = "radio";
		break;
	default:
		printk(KERN_ERR "%s called with unknown type: %d\n",
		       __func__, type);
		return -1;
	}

	/* pick a minor number */
	mutex_lock(&videodev_lock);
	if (nr >= 0  &&  nr < end-base) {
		/* use the one the driver asked for */
		i = base + nr;
		if (NULL != video_device[i]) {
			mutex_unlock(&videodev_lock);
			return -ENFILE;
		}
	} else {
		/* use first free */
		for (i = base; i < end; i++)
			if (NULL == video_device[i])
				break;
		if (i == end) {
			mutex_unlock(&videodev_lock);
			return -ENFILE;
		}
	}
	video_device[i] = vfd;
	vfd->minor = i;

	ret = get_index(vfd, index);
	vfd->index = ret;

	mutex_unlock(&videodev_lock);

	if (ret < 0) {
		printk(KERN_ERR "%s: get_index failed\n", __func__);
		goto fail_minor;
	}

	mutex_init(&vfd->lock);

	/* sysfs class */
	memset(&vfd->dev, 0x00, sizeof(vfd->dev));
	vfd->dev.class = &video_class;
	vfd->dev.devt = MKDEV(VIDEO_MAJOR, vfd->minor);
	if (vfd->parent)
		vfd->dev.parent = vfd->parent;
	sprintf(vfd->dev.bus_id, "%s%d", name_base, i - base);
	ret = device_register(&vfd->dev);
	if (ret < 0) {
		printk(KERN_ERR "%s: device_register failed\n", __func__);
		goto fail_minor;
	}

#if 1
	/* needed until all drivers are fixed */
	if (!vfd->release)
		printk(KERN_WARNING "videodev: \"%s\" has no release callback. "
		       "Please fix your driver for proper sysfs support, see "
		       "http://lwn.net/Articles/36850/\n", vfd->name);
#endif
	return 0;

fail_minor:
	mutex_lock(&videodev_lock);
	video_device[vfd->minor] = NULL;
	vfd->minor = -1;
	mutex_unlock(&videodev_lock);
	return ret;
}
EXPORT_SYMBOL(video_register_device_index);

/**
 *	video_unregister_device - unregister a video4linux device
 *	@vfd: the device to unregister
 *
 *	This unregisters the passed device and deassigns the minor
 *	number. Future open calls will be met with errors.
 */

void video_unregister_device(struct video_device *vfd)
{
	mutex_lock(&videodev_lock);
	if (video_device[vfd->minor] != vfd)
		panic("videodev: bad unregister");

	video_device[vfd->minor] = NULL;
	device_unregister(&vfd->dev);
	mutex_unlock(&videodev_lock);
}
EXPORT_SYMBOL(video_unregister_device);

/*
 * Video fs operations
 */
static const struct file_operations video_fops = {
	.owner		= THIS_MODULE,
	.llseek		= no_llseek,
	.open		= video_open,
};

/*
 *	Initialise video for linux
 */

static int __init videodev_init(void)
{
	int ret;

	printk(KERN_INFO "Linux video capture interface: v2.00\n");
	if (register_chrdev(VIDEO_MAJOR, VIDEO_NAME, &video_fops)) {
		printk(KERN_WARNING "video_dev: unable to get major %d\n", VIDEO_MAJOR);
		return -EIO;
	}

	ret = class_register(&video_class);
	if (ret < 0) {
		unregister_chrdev(VIDEO_MAJOR, VIDEO_NAME);
		printk(KERN_WARNING "video_dev: class_register failed\n");
		return -EIO;
	}

	return 0;
}

static void __exit videodev_exit(void)
{
	class_unregister(&video_class);
	unregister_chrdev(VIDEO_MAJOR, VIDEO_NAME);
}

module_init(videodev_init)
module_exit(videodev_exit)

MODULE_AUTHOR("Alan Cox, Mauro Carvalho Chehab <mchehab@infradead.org>");
MODULE_DESCRIPTION("Device registrar for Video4Linux drivers v2");
MODULE_LICENSE("GPL");


/*
 * Local variables:
 * c-basic-offset: 8
 * End:
 */

Privacy Policy