[deliverable/linux.git] / drivers / media / media-devnode.c

/*
 * Media device node
 *
 * Copyright (C) 2010 Nokia Corporation
 *
 * Based on drivers/media/video/v4l2_dev.c code authored by
 *	Mauro Carvalho Chehab <mchehab@infradead.org> (version 2)
 *	Alan Cox, <alan@lxorguk.ukuu.org.uk> (version 1)
 *
 * Contacts: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
 *	     Sakari Ailus <sakari.ailus@iki.fi>
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License version 2 as
 * published by the Free Software Foundation.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
 *
 * --
 *
 * Generic media device node infrastructure to register and unregister
 * character devices using a dynamic major number and proper reference
 * counting.
 */

#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt

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

#include <media/media-devnode.h>

#define MEDIA_NUM_DEVICES	256
#define MEDIA_NAME		"media"

static dev_t media_dev_t;

/*
 *	Active devices
 */
static DEFINE_MUTEX(media_devnode_lock);
static DECLARE_BITMAP(media_devnode_nums, MEDIA_NUM_DEVICES);

/* Called when the last user of the media device exits. */
static void media_devnode_release(struct device *cd)
{
	struct media_devnode *mdev = to_media_devnode(cd);

	mutex_lock(&media_devnode_lock);

	/* Delete the cdev on this minor as well */
	cdev_del(&mdev->cdev);

	/* Mark device node number as free */
	clear_bit(mdev->minor, media_devnode_nums);

	mutex_unlock(&media_devnode_lock);

	/* Release media_devnode and perform other cleanups as needed. */
	if (mdev->release)
		mdev->release(mdev);
}

static struct bus_type media_bus_type = {
	.name = MEDIA_NAME,
};

static ssize_t media_read(struct file *filp, char __user *buf,
		size_t sz, loff_t *off)
{
	struct media_devnode *mdev = media_devnode_data(filp);

	if (!mdev->fops->read)
		return -EINVAL;
	if (!media_devnode_is_registered(mdev))
		return -EIO;
	return mdev->fops->read(filp, buf, sz, off);
}

static ssize_t media_write(struct file *filp, const char __user *buf,
		size_t sz, loff_t *off)
{
	struct media_devnode *mdev = media_devnode_data(filp);

	if (!mdev->fops->write)
		return -EINVAL;
	if (!media_devnode_is_registered(mdev))
		return -EIO;
	return mdev->fops->write(filp, buf, sz, off);
}

static unsigned int media_poll(struct file *filp,
			       struct poll_table_struct *poll)
{
	struct media_devnode *mdev = media_devnode_data(filp);

	if (!media_devnode_is_registered(mdev))
		return POLLERR | POLLHUP;
	if (!mdev->fops->poll)
		return DEFAULT_POLLMASK;
	return mdev->fops->poll(filp, poll);
}

static long
__media_ioctl(struct file *filp, unsigned int cmd, unsigned long arg,
	      long (*ioctl_func)(struct file *filp, unsigned int cmd,
				 unsigned long arg))
{
	struct media_devnode *mdev = media_devnode_data(filp);

	if (!ioctl_func)
		return -ENOTTY;

	if (!media_devnode_is_registered(mdev))
		return -EIO;

	return ioctl_func(filp, cmd, arg);
}

static long media_ioctl(struct file *filp, unsigned int cmd, unsigned long arg)
{
	struct media_devnode *mdev = media_devnode_data(filp);

	return __media_ioctl(filp, cmd, arg, mdev->fops->ioctl);
}

#ifdef CONFIG_COMPAT

static long media_compat_ioctl(struct file *filp, unsigned int cmd,
			       unsigned long arg)
{
	struct media_devnode *mdev = media_devnode_data(filp);

	return __media_ioctl(filp, cmd, arg, mdev->fops->compat_ioctl);
}

#endif /* CONFIG_COMPAT */

/* Override for the open function */
static int media_open(struct inode *inode, struct file *filp)
{
	struct media_devnode *mdev;
	int ret;

	/* Check if the media device is available. This needs to be done with
	 * the media_devnode_lock held to prevent an open/unregister race:
	 * without the lock, the device could be unregistered and freed between
	 * the media_devnode_is_registered() and get_device() calls, leading to
	 * a crash.
	 */
	mutex_lock(&media_devnode_lock);
	mdev = container_of(inode->i_cdev, struct media_devnode, cdev);
	/* return ENXIO if the media device has been removed
	   already or if it is not registered anymore. */
	if (!media_devnode_is_registered(mdev)) {
		mutex_unlock(&media_devnode_lock);
		return -ENXIO;
	}
	/* and increase the device refcount */
	get_device(&mdev->dev);
	mutex_unlock(&media_devnode_lock);

	filp->private_data = mdev;

	if (mdev->fops->open) {
		ret = mdev->fops->open(filp);
		if (ret) {
			put_device(&mdev->dev);
			filp->private_data = NULL;
			return ret;
		}
	}

	return 0;
}

/* Override for the release function */
static int media_release(struct inode *inode, struct file *filp)
{
	struct media_devnode *mdev = media_devnode_data(filp);

	if (mdev->fops->release)
		mdev->fops->release(filp);

	filp->private_data = NULL;

	/* decrease the refcount unconditionally since the release()
	   return value is ignored. */
	put_device(&mdev->dev);
	return 0;
}

static const struct file_operations media_devnode_fops = {
	.owner = THIS_MODULE,
	.read = media_read,
	.write = media_write,
	.open = media_open,
	.unlocked_ioctl = media_ioctl,
#ifdef CONFIG_COMPAT
	.compat_ioctl = media_compat_ioctl,
#endif /* CONFIG_COMPAT */
	.release = media_release,
	.poll = media_poll,
	.llseek = no_llseek,
};

int __must_check media_devnode_register(struct media_devnode *mdev,
					struct module *owner)
{
	int minor;
	int ret;

	/* Part 1: Find a free minor number */
	mutex_lock(&media_devnode_lock);
	minor = find_next_zero_bit(media_devnode_nums, MEDIA_NUM_DEVICES, 0);
	if (minor == MEDIA_NUM_DEVICES) {
		mutex_unlock(&media_devnode_lock);
		pr_err("could not get a free minor\n");
		return -ENFILE;
	}

	set_bit(minor, media_devnode_nums);
	mutex_unlock(&media_devnode_lock);

	mdev->minor = minor;

	/* Part 2: Initialize and register the character device */
	cdev_init(&mdev->cdev, &media_devnode_fops);
	mdev->cdev.owner = owner;

	ret = cdev_add(&mdev->cdev, MKDEV(MAJOR(media_dev_t), mdev->minor), 1);
	if (ret < 0) {
		pr_err("%s: cdev_add failed\n", __func__);
		goto error;
	}

	/* Part 3: Register the media device */
	mdev->dev.bus = &media_bus_type;
	mdev->dev.devt = MKDEV(MAJOR(media_dev_t), mdev->minor);
	mdev->dev.release = media_devnode_release;
	if (mdev->parent)
		mdev->dev.parent = mdev->parent;
	dev_set_name(&mdev->dev, "media%d", mdev->minor);
	ret = device_register(&mdev->dev);
	if (ret < 0) {
		pr_err("%s: device_register failed\n", __func__);
		goto error;
	}

	/* Part 4: Activate this minor. The char device can now be used. */
	set_bit(MEDIA_FLAG_REGISTERED, &mdev->flags);

	return 0;

error:
	mutex_lock(&media_devnode_lock);
	cdev_del(&mdev->cdev);
	clear_bit(mdev->minor, media_devnode_nums);
	mutex_unlock(&media_devnode_lock);

	return ret;
}

void media_devnode_unregister(struct media_devnode *mdev)
{
	/* Check if mdev was ever registered at all */
	if (!media_devnode_is_registered(mdev))
		return;

	mutex_lock(&media_devnode_lock);
	clear_bit(MEDIA_FLAG_REGISTERED, &mdev->flags);
	mutex_unlock(&media_devnode_lock);
	device_unregister(&mdev->dev);
}

/*
 *	Initialise media for linux
 */
static int __init media_devnode_init(void)
{
	int ret;

	pr_info("Linux media interface: v0.10\n");
	ret = alloc_chrdev_region(&media_dev_t, 0, MEDIA_NUM_DEVICES,
				  MEDIA_NAME);
	if (ret < 0) {
		pr_warn("unable to allocate major\n");
		return ret;
	}

	ret = bus_register(&media_bus_type);
	if (ret < 0) {
		unregister_chrdev_region(media_dev_t, MEDIA_NUM_DEVICES);
		pr_warn("bus_register failed\n");
		return -EIO;
	}

	return 0;
}

static void __exit media_devnode_exit(void)
{
	bus_unregister(&media_bus_type);
	unregister_chrdev_region(media_dev_t, MEDIA_NUM_DEVICES);
}

subsys_initcall(media_devnode_init);
module_exit(media_devnode_exit)

MODULE_AUTHOR("Laurent Pinchart <laurent.pinchart@ideasonboard.com>");
MODULE_DESCRIPTION("Device node registration for media drivers");
MODULE_LICENSE("GPL");
Commit	Line	Data
cf4b9211 LP	1	/*
	2	* Media device node
	3	*
	4	* Copyright (C) 2010 Nokia Corporation
	5	*
	6	* Based on drivers/media/video/v4l2_dev.c code authored by
	7	* Mauro Carvalho Chehab <mchehab@infradead.org> (version 2)
	8	* Alan Cox, <alan@lxorguk.ukuu.org.uk> (version 1)
	9	*
	10	* Contacts: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
	11	* Sakari Ailus <sakari.ailus@iki.fi>
	12	*
	13	* This program is free software; you can redistribute it and/or modify
	14	* it under the terms of the GNU General Public License version 2 as
	15	* published by the Free Software Foundation.
	16	*
	17	* This program is distributed in the hope that it will be useful,
	18	* but WITHOUT ANY WARRANTY; without even the implied warranty of
	19	* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
	20	* GNU General Public License for more details.
	21	*
	22	* You should have received a copy of the GNU General Public License
	23	* along with this program; if not, write to the Free Software
	24	* Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
	25	*
	26	* --
	27	*
	28	* Generic media device node infrastructure to register and unregister
	29	* character devices using a dynamic major number and proper reference
	30	* counting.
	31	*/
	32
3c16b2b3 SK	33	#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
3c16b2b3 SK	34
cf4b9211 LP	35	#include <linux/errno.h>
	36	#include <linux/init.h>
	37	#include <linux/module.h>
	38	#include <linux/kernel.h>
	39	#include <linux/kmod.h>
	40	#include <linux/slab.h>
	41	#include <linux/mm.h>
	42	#include <linux/string.h>
	43	#include <linux/types.h>
	44	#include <linux/uaccess.h>
cf4b9211 LP	45
	46	#include <media/media-devnode.h>
	47
	48	#define MEDIA_NUM_DEVICES 256
	49	#define MEDIA_NAME "media"
	50
	51	static dev_t media_dev_t;
	52
	53	/*
	54	* Active devices
	55	*/
	56	static DEFINE_MUTEX(media_devnode_lock);
	57	static DECLARE_BITMAP(media_devnode_nums, MEDIA_NUM_DEVICES);
	58
	59	/* Called when the last user of the media device exits. */
	60	static void media_devnode_release(struct device *cd)
	61	{
	62	struct media_devnode *mdev = to_media_devnode(cd);
	63
	64	mutex_lock(&media_devnode_lock);
	65
	66	/* Delete the cdev on this minor as well */
	67	cdev_del(&mdev->cdev);
	68
	69	/* Mark device node number as free */
	70	clear_bit(mdev->minor, media_devnode_nums);
	71
	72	mutex_unlock(&media_devnode_lock);
	73
	74	/* Release media_devnode and perform other cleanups as needed. */
	75	if (mdev->release)
	76	mdev->release(mdev);
	77	}
	78
	79	static struct bus_type media_bus_type = {
	80	.name = MEDIA_NAME,
	81	};
	82
	83	static ssize_t media_read(struct file filp, char __user buf,
	84	size_t sz, loff_t *off)
	85	{
	86	struct media_devnode *mdev = media_devnode_data(filp);
	87
	88	if (!mdev->fops->read)
	89	return -EINVAL;
	90	if (!media_devnode_is_registered(mdev))
	91	return -EIO;
	92	return mdev->fops->read(filp, buf, sz, off);
	93	}
	94
	95	static ssize_t media_write(struct file filp, const char __user buf,
	96	size_t sz, loff_t *off)
	97	{
	98	struct media_devnode *mdev = media_devnode_data(filp);
	99
	100	if (!mdev->fops->write)
	101	return -EINVAL;
	102	if (!media_devnode_is_registered(mdev))
	103	return -EIO;
	104	return mdev->fops->write(filp, buf, sz, off);
	105	}
	106
	107	static unsigned int media_poll(struct file *filp,
	108	struct poll_table_struct *poll)
109	{
110	struct media_devnode *mdev = media_devnode_data(filp);
111
112	if (!media_devnode_is_registered(mdev))
113	return POLLERR \| POLLHUP;
114	if (!mdev->fops->poll)
115	return DEFAULT_POLLMASK;
116	return mdev->fops->poll(filp, poll);
117	}
118
c6c1d50b SA	119	static long
	120	__media_ioctl(struct file *filp, unsigned int cmd, unsigned long arg,
	121	long (ioctl_func)(struct file filp, unsigned int cmd,
	122	unsigned long arg))
cf4b9211 LP	123	{
	124	struct media_devnode *mdev = media_devnode_data(filp);
	125
c6c1d50b	126	if (!ioctl_func)
cf4b9211 LP	127	return -ENOTTY;
	128
	129	if (!media_devnode_is_registered(mdev))
	130	return -EIO;
	131
c6c1d50b SA	132	return ioctl_func(filp, cmd, arg);
	133	}
	134
	135	static long media_ioctl(struct file *filp, unsigned int cmd, unsigned long arg)
	136	{
	137	struct media_devnode *mdev = media_devnode_data(filp);
	138
	139	return __media_ioctl(filp, cmd, arg, mdev->fops->ioctl);
cf4b9211 LP	140	}
cf4b9211 LP	141
c6c1d50b SA	142	#ifdef CONFIG_COMPAT
	143
	144	static long media_compat_ioctl(struct file *filp, unsigned int cmd,
	145	unsigned long arg)
	146	{
	147	struct media_devnode *mdev = media_devnode_data(filp);
	148
	149	return __media_ioctl(filp, cmd, arg, mdev->fops->compat_ioctl);
	150	}
	151
	152	#endif /* CONFIG_COMPAT */
	153
cf4b9211 LP	154	/* Override for the open function */
	155	static int media_open(struct inode inode, struct file filp)
	156	{
	157	struct media_devnode *mdev;
	158	int ret;
	159
	160	/* Check if the media device is available. This needs to be done with
	161	* the media_devnode_lock held to prevent an open/unregister race:
	162	* without the lock, the device could be unregistered and freed between
	163	* the media_devnode_is_registered() and get_device() calls, leading to
	164	* a crash.
	165	*/
	166	mutex_lock(&media_devnode_lock);
	167	mdev = container_of(inode->i_cdev, struct media_devnode, cdev);
	168	/* return ENXIO if the media device has been removed
	169	already or if it is not registered anymore. */
	170	if (!media_devnode_is_registered(mdev)) {
	171	mutex_unlock(&media_devnode_lock);
	172	return -ENXIO;
	173	}
	174	/* and increase the device refcount */
	175	get_device(&mdev->dev);
	176	mutex_unlock(&media_devnode_lock);
	177
	178	filp->private_data = mdev;
	179
	180	if (mdev->fops->open) {
	181	ret = mdev->fops->open(filp);
	182	if (ret) {
	183	put_device(&mdev->dev);
d40ec6fd	184	filp->private_data = NULL;
cf4b9211 LP	185	return ret;
	186	}
	187	}
	188
	189	return 0;
	190	}
	191
	192	/* Override for the release function */
	193	static int media_release(struct inode inode, struct file filp)
	194	{
	195	struct media_devnode *mdev = media_devnode_data(filp);
cf4b9211 LP	196
	197	if (mdev->fops->release)
	198	mdev->fops->release(filp);
	199
bf244f66 MK	200	filp->private_data = NULL;
bf244f66 MK	201
cf4b9211 LP	202	/* decrease the refcount unconditionally since the release()
	203	return value is ignored. */
	204	put_device(&mdev->dev);
8b37c645	205	return 0;
cf4b9211 LP	206	}
	207
	208	static const struct file_operations media_devnode_fops = {
	209	.owner = THIS_MODULE,
	210	.read = media_read,
	211	.write = media_write,
	212	.open = media_open,
	213	.unlocked_ioctl = media_ioctl,
c6c1d50b SA	214	#ifdef CONFIG_COMPAT
	215	.compat_ioctl = media_compat_ioctl,
	216	#endif /* CONFIG_COMPAT */
cf4b9211 LP	217	.release = media_release,
	218	.poll = media_poll,
	219	.llseek = no_llseek,
	220	};
	221
85de721c SA	222	int __must_check media_devnode_register(struct media_devnode *mdev,
85de721c SA	223	struct module *owner)
cf4b9211 LP	224	{
	225	int minor;
	226	int ret;
	227
	228	/* Part 1: Find a free minor number */
	229	mutex_lock(&media_devnode_lock);
8c89ddd5	230	minor = find_next_zero_bit(media_devnode_nums, MEDIA_NUM_DEVICES, 0);
cf4b9211 LP	231	if (minor == MEDIA_NUM_DEVICES) {
cf4b9211 LP	232	mutex_unlock(&media_devnode_lock);
3c16b2b3	233	pr_err("could not get a free minor\n");
cf4b9211 LP	234	return -ENFILE;
	235	}
	236
8c89ddd5	237	set_bit(minor, media_devnode_nums);
cf4b9211 LP	238	mutex_unlock(&media_devnode_lock);
	239
	240	mdev->minor = minor;
	241
	242	/* Part 2: Initialize and register the character device */
	243	cdev_init(&mdev->cdev, &media_devnode_fops);
85de721c	244	mdev->cdev.owner = owner;
cf4b9211 LP	245
	246	ret = cdev_add(&mdev->cdev, MKDEV(MAJOR(media_dev_t), mdev->minor), 1);
	247	if (ret < 0) {
3c16b2b3	248	pr_err("%s: cdev_add failed\n", __func__);
cf4b9211 LP	249	goto error;
	250	}
	251
	252	/* Part 3: Register the media device */
	253	mdev->dev.bus = &media_bus_type;
	254	mdev->dev.devt = MKDEV(MAJOR(media_dev_t), mdev->minor);
	255	mdev->dev.release = media_devnode_release;
	256	if (mdev->parent)
	257	mdev->dev.parent = mdev->parent;
	258	dev_set_name(&mdev->dev, "media%d", mdev->minor);
	259	ret = device_register(&mdev->dev);
	260	if (ret < 0) {
3c16b2b3	261	pr_err("%s: device_register failed\n", __func__);
cf4b9211 LP	262	goto error;
	263	}
	264
	265	/* Part 4: Activate this minor. The char device can now be used. */
	266	set_bit(MEDIA_FLAG_REGISTERED, &mdev->flags);
	267
	268	return 0;
	269
	270	error:
88336e17	271	mutex_lock(&media_devnode_lock);
cf4b9211 LP	272	cdev_del(&mdev->cdev);
cf4b9211 LP	273	clear_bit(mdev->minor, media_devnode_nums);
88336e17 MK	274	mutex_unlock(&media_devnode_lock);
88336e17 MK	275
cf4b9211 LP	276	return ret;
	277	}
	278
cf4b9211 LP	279	void media_devnode_unregister(struct media_devnode *mdev)
	280	{
	281	/* Check if mdev was ever registered at all */
	282	if (!media_devnode_is_registered(mdev))
	283	return;
	284
	285	mutex_lock(&media_devnode_lock);
	286	clear_bit(MEDIA_FLAG_REGISTERED, &mdev->flags);
	287	mutex_unlock(&media_devnode_lock);
	288	device_unregister(&mdev->dev);
	289	}
	290
	291	/*
	292	* Initialise media for linux
	293	*/
	294	static int __init media_devnode_init(void)
	295	{
	296	int ret;
	297
3c16b2b3	298	pr_info("Linux media interface: v0.10\n");
cf4b9211 LP	299	ret = alloc_chrdev_region(&media_dev_t, 0, MEDIA_NUM_DEVICES,
	300	MEDIA_NAME);
	301	if (ret < 0) {
3c16b2b3	302	pr_warn("unable to allocate major\n");
cf4b9211 LP	303	return ret;
	304	}
	305
	306	ret = bus_register(&media_bus_type);
	307	if (ret < 0) {
	308	unregister_chrdev_region(media_dev_t, MEDIA_NUM_DEVICES);
3c16b2b3	309	pr_warn("bus_register failed\n");
cf4b9211 LP	310	return -EIO;
	311	}
	312
	313	return 0;
	314	}
	315
	316	static void __exit media_devnode_exit(void)
	317	{
	318	bus_unregister(&media_bus_type);
	319	unregister_chrdev_region(media_dev_t, MEDIA_NUM_DEVICES);
	320	}
	321
ff732d28	322	subsys_initcall(media_devnode_init);
cf4b9211 LP	323	module_exit(media_devnode_exit)
	324
	325	MODULE_AUTHOR("Laurent Pinchart <laurent.pinchart@ideasonboard.com>");
	326	MODULE_DESCRIPTION("Device node registration for media drivers");
	327	MODULE_LICENSE("GPL");