[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>
#include <media/media-device.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 *devnode = to_media_devnode(cd);

	mutex_lock(&media_devnode_lock);
	/* Mark device node number as free */
	clear_bit(devnode->minor, media_devnode_nums);
	mutex_unlock(&media_devnode_lock);

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

	kfree(devnode);
	pr_debug("%s: Media Devnode Deallocated\n", __func__);
}

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 *devnode = media_devnode_data(filp);

	if (!devnode->fops->read)
		return -EINVAL;
	if (!media_devnode_is_registered(devnode))
		return -EIO;
	return devnode->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 *devnode = media_devnode_data(filp);

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

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

	if (!media_devnode_is_registered(devnode))
		return POLLERR | POLLHUP;
	if (!devnode->fops->poll)
		return DEFAULT_POLLMASK;
	return devnode->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 *devnode = media_devnode_data(filp);

	if (!ioctl_func)
		return -ENOTTY;

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

	return ioctl_func(filp, cmd, arg);
}

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

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

#ifdef CONFIG_COMPAT

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

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

#endif /* CONFIG_COMPAT */

/* Override for the open function */
static int media_open(struct inode *inode, struct file *filp)
{
	struct media_devnode *devnode;
	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);
	devnode = 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(devnode)) {
		mutex_unlock(&media_devnode_lock);
		return -ENXIO;
	}
	/* and increase the device refcount */
	get_device(&devnode->dev);
	mutex_unlock(&media_devnode_lock);

	filp->private_data = devnode;

	if (devnode->fops->open) {
		ret = devnode->fops->open(filp);
		if (ret) {
			put_device(&devnode->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 *devnode = media_devnode_data(filp);

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

	filp->private_data = NULL;

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

	pr_debug("%s: Media Release\n", __func__);
	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_device *mdev,
					struct media_devnode *devnode,
					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");
		kfree(devnode);
		return -ENFILE;
	}

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

	devnode->minor = minor;
	devnode->media_dev = mdev;

	/* Part 1: Initialize dev now to use dev.kobj for cdev.kobj.parent */
	devnode->dev.bus = &media_bus_type;
	devnode->dev.devt = MKDEV(MAJOR(media_dev_t), devnode->minor);
	devnode->dev.release = media_devnode_release;
	if (devnode->parent)
		devnode->dev.parent = devnode->parent;
	dev_set_name(&devnode->dev, "media%d", devnode->minor);
	device_initialize(&devnode->dev);

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

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

	/* Part 3: Add the media device */
	ret = device_add(&devnode->dev);
	if (ret < 0) {
		pr_err("%s: device_add failed\n", __func__);
		goto device_add_error;
	}

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

	return 0;

device_add_error:
	cdev_del(&devnode->cdev);
cdev_add_error:
	mutex_lock(&media_devnode_lock);
	clear_bit(devnode->minor, media_devnode_nums);
	devnode->media_dev = NULL;
	mutex_unlock(&media_devnode_lock);

	put_device(&devnode->dev);
	return ret;
}

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

	mutex_lock(&media_devnode_lock);
	clear_bit(MEDIA_FLAG_REGISTERED, &devnode->flags);
	mutex_unlock(&media_devnode_lock);
}

void media_devnode_unregister(struct media_devnode *devnode)
{
	mutex_lock(&media_devnode_lock);
	/* Delete the cdev on this minor as well */
	cdev_del(&devnode->cdev);
	mutex_unlock(&media_devnode_lock);
	device_del(&devnode->dev);
	devnode->media_dev = NULL;
	put_device(&devnode->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
	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
	33	#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
	34
	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>
	45
	46	#include <media/media-devnode.h>
	47	#include <media/media-device.h>
	48
	49	#define MEDIA_NUM_DEVICES 256
	50	#define MEDIA_NAME "media"
	51
	52	static dev_t media_dev_t;
	53
	54	/*
	55	* Active devices
	56	*/
	57	static DEFINE_MUTEX(media_devnode_lock);
	58	static DECLARE_BITMAP(media_devnode_nums, MEDIA_NUM_DEVICES);
	59
	60	/* Called when the last user of the media device exits. */
	61	static void media_devnode_release(struct device *cd)
	62	{
	63	struct media_devnode *devnode = to_media_devnode(cd);
	64
	65	mutex_lock(&media_devnode_lock);
	66	/* Mark device node number as free */
	67	clear_bit(devnode->minor, media_devnode_nums);
	68	mutex_unlock(&media_devnode_lock);
	69
	70	/* Release media_devnode and perform other cleanups as needed. */
	71	if (devnode->release)
	72	devnode->release(devnode);
	73
	74	kfree(devnode);
	75	pr_debug("%s: Media Devnode Deallocated\n", __func__);
	76	}
	77
	78	static struct bus_type media_bus_type = {
	79	.name = MEDIA_NAME,
	80	};
	81
	82	static ssize_t media_read(struct file filp, char __user buf,
	83	size_t sz, loff_t *off)
	84	{
	85	struct media_devnode *devnode = media_devnode_data(filp);
	86
	87	if (!devnode->fops->read)
	88	return -EINVAL;
	89	if (!media_devnode_is_registered(devnode))
	90	return -EIO;
	91	return devnode->fops->read(filp, buf, sz, off);
	92	}
	93
	94	static ssize_t media_write(struct file filp, const char __user buf,
	95	size_t sz, loff_t *off)
	96	{
	97	struct media_devnode *devnode = media_devnode_data(filp);
	98
	99	if (!devnode->fops->write)
	100	return -EINVAL;
	101	if (!media_devnode_is_registered(devnode))
	102	return -EIO;
	103	return devnode->fops->write(filp, buf, sz, off);
	104	}
	105
	106	static unsigned int media_poll(struct file *filp,
	107	struct poll_table_struct *poll)
	108	{
	109	struct media_devnode *devnode = media_devnode_data(filp);
	110
	111	if (!media_devnode_is_registered(devnode))
	112	return POLLERR \| POLLHUP;
	113	if (!devnode->fops->poll)
	114	return DEFAULT_POLLMASK;
	115	return devnode->fops->poll(filp, poll);
	116	}
	117
	118	static long
	119	__media_ioctl(struct file *filp, unsigned int cmd, unsigned long arg,
	120	long (ioctl_func)(struct file filp, unsigned int cmd,
	121	unsigned long arg))
	122	{
	123	struct media_devnode *devnode = media_devnode_data(filp);
	124
	125	if (!ioctl_func)
	126	return -ENOTTY;
	127
	128	if (!media_devnode_is_registered(devnode))
	129	return -EIO;
	130
	131	return ioctl_func(filp, cmd, arg);
	132	}
	133
	134	static long media_ioctl(struct file *filp, unsigned int cmd, unsigned long arg)
	135	{
	136	struct media_devnode *devnode = media_devnode_data(filp);
	137
	138	return __media_ioctl(filp, cmd, arg, devnode->fops->ioctl);
	139	}
	140
	141	#ifdef CONFIG_COMPAT
	142
	143	static long media_compat_ioctl(struct file *filp, unsigned int cmd,
	144	unsigned long arg)
	145	{
	146	struct media_devnode *devnode = media_devnode_data(filp);
	147
	148	return __media_ioctl(filp, cmd, arg, devnode->fops->compat_ioctl);
	149	}
	150
	151	#endif /* CONFIG_COMPAT */
	152
	153	/* Override for the open function */
	154	static int media_open(struct inode inode, struct file filp)
	155	{
	156	struct media_devnode *devnode;
	157	int ret;
	158
	159	/* Check if the media device is available. This needs to be done with
	160	* the media_devnode_lock held to prevent an open/unregister race:
	161	* without the lock, the device could be unregistered and freed between
	162	* the media_devnode_is_registered() and get_device() calls, leading to
	163	* a crash.
	164	*/
	165	mutex_lock(&media_devnode_lock);
	166	devnode = container_of(inode->i_cdev, struct media_devnode, cdev);
	167	/* return ENXIO if the media device has been removed
	168	already or if it is not registered anymore. */
	169	if (!media_devnode_is_registered(devnode)) {
	170	mutex_unlock(&media_devnode_lock);
	171	return -ENXIO;
	172	}
	173	/* and increase the device refcount */
	174	get_device(&devnode->dev);
	175	mutex_unlock(&media_devnode_lock);
	176
	177	filp->private_data = devnode;
	178
	179	if (devnode->fops->open) {
	180	ret = devnode->fops->open(filp);
	181	if (ret) {
	182	put_device(&devnode->dev);
	183	filp->private_data = NULL;
	184	return ret;
	185	}
	186	}
	187
	188	return 0;
	189	}
	190
	191	/* Override for the release function */
	192	static int media_release(struct inode inode, struct file filp)
	193	{
	194	struct media_devnode *devnode = media_devnode_data(filp);
	195
	196	if (devnode->fops->release)
	197	devnode->fops->release(filp);
	198
	199	filp->private_data = NULL;
	200
	201	/* decrease the refcount unconditionally since the release()
	202	return value is ignored. */
	203	put_device(&devnode->dev);
	204
	205	pr_debug("%s: Media Release\n", __func__);
	206	return 0;
	207	}
	208
	209	static const struct file_operations media_devnode_fops = {
	210	.owner = THIS_MODULE,
	211	.read = media_read,
	212	.write = media_write,
	213	.open = media_open,
	214	.unlocked_ioctl = media_ioctl,
	215	#ifdef CONFIG_COMPAT
	216	.compat_ioctl = media_compat_ioctl,
	217	#endif /* CONFIG_COMPAT */
	218	.release = media_release,
	219	.poll = media_poll,
	220	.llseek = no_llseek,
	221	};
	222
	223	int __must_check media_devnode_register(struct media_device *mdev,
	224	struct media_devnode *devnode,
	225	struct module *owner)
	226	{
	227	int minor;
	228	int ret;
	229
	230	/* Part 1: Find a free minor number */
	231	mutex_lock(&media_devnode_lock);
	232	minor = find_next_zero_bit(media_devnode_nums, MEDIA_NUM_DEVICES, 0);
	233	if (minor == MEDIA_NUM_DEVICES) {
	234	mutex_unlock(&media_devnode_lock);
	235	pr_err("could not get a free minor\n");
	236	kfree(devnode);
	237	return -ENFILE;
	238	}
	239
	240	set_bit(minor, media_devnode_nums);
	241	mutex_unlock(&media_devnode_lock);
	242
	243	devnode->minor = minor;
	244	devnode->media_dev = mdev;
	245
	246	/* Part 1: Initialize dev now to use dev.kobj for cdev.kobj.parent */
	247	devnode->dev.bus = &media_bus_type;
	248	devnode->dev.devt = MKDEV(MAJOR(media_dev_t), devnode->minor);
	249	devnode->dev.release = media_devnode_release;
	250	if (devnode->parent)
	251	devnode->dev.parent = devnode->parent;
	252	dev_set_name(&devnode->dev, "media%d", devnode->minor);
	253	device_initialize(&devnode->dev);
	254
	255	/* Part 2: Initialize and register the character device */
	256	cdev_init(&devnode->cdev, &media_devnode_fops);
	257	devnode->cdev.owner = owner;
	258	devnode->cdev.kobj.parent = &devnode->dev.kobj;
	259
	260	ret = cdev_add(&devnode->cdev, MKDEV(MAJOR(media_dev_t), devnode->minor), 1);
	261	if (ret < 0) {
	262	pr_err("%s: cdev_add failed\n", __func__);
	263	goto cdev_add_error;
	264	}
	265
	266	/* Part 3: Add the media device */
	267	ret = device_add(&devnode->dev);
	268	if (ret < 0) {
	269	pr_err("%s: device_add failed\n", __func__);
	270	goto device_add_error;
	271	}
	272
	273	/* Part 4: Activate this minor. The char device can now be used. */
	274	set_bit(MEDIA_FLAG_REGISTERED, &devnode->flags);
	275
	276	return 0;
	277
	278	device_add_error:
	279	cdev_del(&devnode->cdev);
	280	cdev_add_error:
	281	mutex_lock(&media_devnode_lock);
	282	clear_bit(devnode->minor, media_devnode_nums);
	283	devnode->media_dev = NULL;
	284	mutex_unlock(&media_devnode_lock);
	285
	286	put_device(&devnode->dev);
	287	return ret;
	288	}
	289
	290	void media_devnode_unregister_prepare(struct media_devnode *devnode)
	291	{
	292	/* Check if devnode was ever registered at all */
	293	if (!media_devnode_is_registered(devnode))
	294	return;
	295
	296	mutex_lock(&media_devnode_lock);
	297	clear_bit(MEDIA_FLAG_REGISTERED, &devnode->flags);
	298	mutex_unlock(&media_devnode_lock);
	299	}
	300
	301	void media_devnode_unregister(struct media_devnode *devnode)
	302	{
	303	mutex_lock(&media_devnode_lock);
	304	/* Delete the cdev on this minor as well */
	305	cdev_del(&devnode->cdev);
	306	mutex_unlock(&media_devnode_lock);
	307	device_del(&devnode->dev);
	308	devnode->media_dev = NULL;
	309	put_device(&devnode->dev);
	310	}
	311
	312	/*
	313	* Initialise media for linux
	314	*/
	315	static int __init media_devnode_init(void)
	316	{
	317	int ret;
	318
	319	pr_info("Linux media interface: v0.10\n");
	320	ret = alloc_chrdev_region(&media_dev_t, 0, MEDIA_NUM_DEVICES,
	321	MEDIA_NAME);
	322	if (ret < 0) {
	323	pr_warn("unable to allocate major\n");
	324	return ret;
	325	}
	326
	327	ret = bus_register(&media_bus_type);
	328	if (ret < 0) {
	329	unregister_chrdev_region(media_dev_t, MEDIA_NUM_DEVICES);
	330	pr_warn("bus_register failed\n");
	331	return -EIO;
	332	}
	333
	334	return 0;
	335	}
	336
	337	static void __exit media_devnode_exit(void)
	338	{
	339	bus_unregister(&media_bus_type);
	340	unregister_chrdev_region(media_dev_t, MEDIA_NUM_DEVICES);
	341	}
	342
	343	subsys_initcall(media_devnode_init);
	344	module_exit(media_devnode_exit)
	345
	346	MODULE_AUTHOR("Laurent Pinchart <laurent.pinchart@ideasonboard.com>");
	347	MODULE_DESCRIPTION("Device node registration for media drivers");
	348	MODULE_LICENSE("GPL");