[mirror_ubuntu-zesty-kernel.git] / drivers / char / misc.c

/*
 * linux/drivers/char/misc.c
 *
 * Generic misc open routine by Johan Myreen
 *
 * Based on code from Linus
 *
 * Teemu Rantanen's Microsoft Busmouse support and Derrick Cole's
 *   changes incorporated into 0.97pl4
 *   by Peter Cervasio (pete%q106fm.uucp@wupost.wustl.edu) (08SEP92)
 *   See busmouse.c for particulars.
 *
 * Made things a lot mode modular - easy to compile in just one or two
 * of the misc drivers, as they are now completely independent. Linus.
 *
 * Support for loadable modules. 8-Sep-95 Philip Blundell <pjb27@cam.ac.uk>
 *
 * Fixed a failing symbol register to free the device registration
 *		Alan Cox <alan@lxorguk.ukuu.org.uk> 21-Jan-96
 *
 * Dynamic minors and /proc/mice by Alessandro Rubini. 26-Mar-96
 *
 * Renamed to misc and miscdevice to be more accurate. Alan Cox 26-Mar-96
 *
 * Handling of mouse minor numbers for kerneld:
 *  Idea by Jacques Gelinas <jack@solucorp.qc.ca>,
 *  adapted by Bjorn Ekwall <bj0rn@blox.se>
 *  corrected by Alan Cox <alan@lxorguk.ukuu.org.uk>
 *
 * Changes for kmod (from kerneld):
 *	Cyrus Durgin <cider@speakeasy.org>
 *
 * Added devfs support. Richard Gooch <rgooch@atnf.csiro.au>  10-Jan-1998
 */

#include <linux/module.h>

#include <linux/fs.h>
#include <linux/errno.h>
#include <linux/miscdevice.h>
#include <linux/kernel.h>
#include <linux/major.h>
#include <linux/mutex.h>
#include <linux/proc_fs.h>
#include <linux/seq_file.h>
#include <linux/stat.h>
#include <linux/init.h>
#include <linux/device.h>
#include <linux/tty.h>
#include <linux/kmod.h>
#include <linux/gfp.h>

/*
 * Head entry for the doubly linked miscdevice list
 */
static LIST_HEAD(misc_list);
static DEFINE_MUTEX(misc_mtx);

/*
 * Assigned numbers, used for dynamic minors
 */
#define DYNAMIC_MINORS 64 /* like dynamic majors */
static DECLARE_BITMAP(misc_minors, DYNAMIC_MINORS);

#ifdef CONFIG_PROC_FS
static void *misc_seq_start(struct seq_file *seq, loff_t *pos)
{
	mutex_lock(&misc_mtx);
	return seq_list_start(&misc_list, *pos);
}

static void *misc_seq_next(struct seq_file *seq, void *v, loff_t *pos)
{
	return seq_list_next(v, &misc_list, pos);
}

static void misc_seq_stop(struct seq_file *seq, void *v)
{
	mutex_unlock(&misc_mtx);
}

static int misc_seq_show(struct seq_file *seq, void *v)
{
	const struct miscdevice *p = list_entry(v, struct miscdevice, list);

	seq_printf(seq, "%3i %s\n", p->minor, p->name ? p->name : "");
	return 0;
}


static const struct seq_operations misc_seq_ops = {
	.start = misc_seq_start,
	.next  = misc_seq_next,
	.stop  = misc_seq_stop,
	.show  = misc_seq_show,
};

static int misc_seq_open(struct inode *inode, struct file *file)
{
	return seq_open(file, &misc_seq_ops);
}

static const struct file_operations misc_proc_fops = {
	.owner	 = THIS_MODULE,
	.open    = misc_seq_open,
	.read    = seq_read,
	.llseek  = seq_lseek,
	.release = seq_release,
};
#endif

static int misc_open(struct inode * inode, struct file * file)
{
	int minor = iminor(inode);
	struct miscdevice *c;
	int err = -ENODEV;
	const struct file_operations *new_fops = NULL;

	mutex_lock(&misc_mtx);

	list_for_each_entry(c, &misc_list, list) {
		if (c->minor == minor) {
			new_fops = fops_get(c->fops);
			break;
		}
	}

	if (!new_fops) {
		mutex_unlock(&misc_mtx);
		request_module("char-major-%d-%d", MISC_MAJOR, minor);
		mutex_lock(&misc_mtx);

		list_for_each_entry(c, &misc_list, list) {
			if (c->minor == minor) {
				new_fops = fops_get(c->fops);
				break;
			}
		}
		if (!new_fops)
			goto fail;
	}

	/*
	 * Place the miscdevice in the file's
	 * private_data so it can be used by the
	 * file operations, including f_op->open below
	 */
	file->private_data = c;

	err = 0;
	replace_fops(file, new_fops);
	if (file->f_op->open)
		err = file->f_op->open(inode,file);
fail:
	mutex_unlock(&misc_mtx);
	return err;
}

static struct class *misc_class;

static const struct file_operations misc_fops = {
	.owner		= THIS_MODULE,
	.open		= misc_open,
	.llseek		= noop_llseek,
};

/**
 *	misc_register	-	register a miscellaneous device
 *	@misc: device structure
 *
 *	Register a miscellaneous device with the kernel. If the minor
 *	number is set to %MISC_DYNAMIC_MINOR a minor number is assigned
 *	and placed in the minor field of the structure. For other cases
 *	the minor number requested is used.
 *
 *	The structure passed is linked into the kernel and may not be
 *	destroyed until it has been unregistered. By default, an open()
 *	syscall to the device sets file->private_data to point to the
 *	structure. Drivers don't need open in fops for this.
 *
 *	A zero is returned on success and a negative errno code for
 *	failure.
 */

int misc_register(struct miscdevice * misc)
{
	dev_t dev;
	int err = 0;
	bool is_dynamic = (misc->minor == MISC_DYNAMIC_MINOR);

	INIT_LIST_HEAD(&misc->list);

	mutex_lock(&misc_mtx);

	if (is_dynamic) {
		int i = find_first_zero_bit(misc_minors, DYNAMIC_MINORS);
		if (i >= DYNAMIC_MINORS) {
			err = -EBUSY;
			goto out;
		}
		misc->minor = DYNAMIC_MINORS - i - 1;
		set_bit(i, misc_minors);
	} else {
		struct miscdevice *c;

		list_for_each_entry(c, &misc_list, list) {
			if (c->minor == misc->minor) {
				err = -EBUSY;
				goto out;
			}
		}
	}

	dev = MKDEV(MISC_MAJOR, misc->minor);

	misc->this_device =
		device_create_with_groups(misc_class, misc->parent, dev,
					  misc, misc->groups, "%s", misc->name);
	if (IS_ERR(misc->this_device)) {
		if (is_dynamic) {
			int i = DYNAMIC_MINORS - misc->minor - 1;

			if (i < DYNAMIC_MINORS && i >= 0)
				clear_bit(i, misc_minors);
			misc->minor = MISC_DYNAMIC_MINOR;
		}
		err = PTR_ERR(misc->this_device);
		goto out;
	}

	/*
	 * Add it to the front, so that later devices can "override"
	 * earlier defaults
	 */
	list_add(&misc->list, &misc_list);
 out:
	mutex_unlock(&misc_mtx);
	return err;
}

/**
 *	misc_deregister - unregister a miscellaneous device
 *	@misc: device to unregister
 *
 *	Unregister a miscellaneous device that was previously
 *	successfully registered with misc_register().
 */

void misc_deregister(struct miscdevice *misc)
{
	int i = DYNAMIC_MINORS - misc->minor - 1;

	if (WARN_ON(list_empty(&misc->list)))
		return;

	mutex_lock(&misc_mtx);
	list_del(&misc->list);
	device_destroy(misc_class, MKDEV(MISC_MAJOR, misc->minor));
	if (i < DYNAMIC_MINORS && i >= 0)
		clear_bit(i, misc_minors);
	mutex_unlock(&misc_mtx);
}

EXPORT_SYMBOL(misc_register);
EXPORT_SYMBOL(misc_deregister);

static char *misc_devnode(struct device *dev, umode_t *mode)
{
	struct miscdevice *c = dev_get_drvdata(dev);

	if (mode && c->mode)
		*mode = c->mode;
	if (c->nodename)
		return kstrdup(c->nodename, GFP_KERNEL);
	return NULL;
}

static int __init misc_init(void)
{
	int err;
	struct proc_dir_entry *ret;

	ret = proc_create("misc", 0, NULL, &misc_proc_fops);
	misc_class = class_create(THIS_MODULE, "misc");
	err = PTR_ERR(misc_class);
	if (IS_ERR(misc_class))
		goto fail_remove;

	err = -EIO;
	if (register_chrdev(MISC_MAJOR,"misc",&misc_fops))
		goto fail_printk;
	misc_class->devnode = misc_devnode;
	return 0;

fail_printk:
	printk("unable to get major %d for misc devices\n", MISC_MAJOR);
	class_destroy(misc_class);
fail_remove:
	if (ret)
		remove_proc_entry("misc", NULL);
	return err;
}
subsys_initcall(misc_init);
Commit	Line	Data
1da177e4 LT	1	/*
	2	* linux/drivers/char/misc.c
	3	*
	4	* Generic misc open routine by Johan Myreen
	5	*
	6	* Based on code from Linus
	7	*
	8	* Teemu Rantanen's Microsoft Busmouse support and Derrick Cole's
	9	* changes incorporated into 0.97pl4
	10	* by Peter Cervasio (pete%q106fm.uucp@wupost.wustl.edu) (08SEP92)
	11	* See busmouse.c for particulars.
	12	*
	13	* Made things a lot mode modular - easy to compile in just one or two
	14	* of the misc drivers, as they are now completely independent. Linus.
	15	*
	16	* Support for loadable modules. 8-Sep-95 Philip Blundell <pjb27@cam.ac.uk>
	17	*
	18	* Fixed a failing symbol register to free the device registration
	19	* Alan Cox <alan@lxorguk.ukuu.org.uk> 21-Jan-96
	20	*
	21	* Dynamic minors and /proc/mice by Alessandro Rubini. 26-Mar-96
	22	*
	23	* Renamed to misc and miscdevice to be more accurate. Alan Cox 26-Mar-96
	24	*
	25	* Handling of mouse minor numbers for kerneld:
	26	* Idea by Jacques Gelinas <jack@solucorp.qc.ca>,
	27	* adapted by Bjorn Ekwall <bj0rn@blox.se>
	28	* corrected by Alan Cox <alan@lxorguk.ukuu.org.uk>
	29	*
	30	* Changes for kmod (from kerneld):
	31	* Cyrus Durgin <cider@speakeasy.org>
	32	*
	33	* Added devfs support. Richard Gooch <rgooch@atnf.csiro.au> 10-Jan-1998
	34	*/
	35
	36	#include <linux/module.h>
1da177e4 LT	37
	38	#include <linux/fs.h>
	39	#include <linux/errno.h>
	40	#include <linux/miscdevice.h>
	41	#include <linux/kernel.h>
	42	#include <linux/major.h>
0e82d5b6	43	#include <linux/mutex.h>
1da177e4 LT	44	#include <linux/proc_fs.h>
1da177e4 LT	45	#include <linux/seq_file.h>
1da177e4 LT	46	#include <linux/stat.h>
	47	#include <linux/init.h>
	48	#include <linux/device.h>
	49	#include <linux/tty.h>
	50	#include <linux/kmod.h>
5a0e3ad6	51	#include <linux/gfp.h>
1da177e4 LT	52
	53	/*
	54	* Head entry for the doubly linked miscdevice list
	55	*/
	56	static LIST_HEAD(misc_list);
0e82d5b6	57	static DEFINE_MUTEX(misc_mtx);
1da177e4 LT	58
	59	/*
	60	* Assigned numbers, used for dynamic minors
	61	*/
	62	#define DYNAMIC_MINORS 64 /* like dynamic majors */
1f2f38d8	63	static DECLARE_BITMAP(misc_minors, DYNAMIC_MINORS);
1da177e4	64
1da177e4 LT	65	#ifdef CONFIG_PROC_FS
	66	static void misc_seq_start(struct seq_file seq, loff_t *pos)
	67	{
0e82d5b6	68	mutex_lock(&misc_mtx);
46c65b71	69	return seq_list_start(&misc_list, *pos);
1da177e4 LT	70	}
	71
	72	static void misc_seq_next(struct seq_file seq, void v, loff_t pos)
	73	{
46c65b71	74	return seq_list_next(v, &misc_list, pos);
1da177e4 LT	75	}
	76
	77	static void misc_seq_stop(struct seq_file seq, void v)
	78	{
0e82d5b6	79	mutex_unlock(&misc_mtx);
1da177e4 LT	80	}
	81
	82	static int misc_seq_show(struct seq_file seq, void v)
	83	{
46c65b71	84	const struct miscdevice *p = list_entry(v, struct miscdevice, list);
1da177e4 LT	85
	86	seq_printf(seq, "%3i %s\n", p->minor, p->name ? p->name : "");
	87	return 0;
	88	}
	89
	90
88e9d34c	91	static const struct seq_operations misc_seq_ops = {
1da177e4 LT	92	.start = misc_seq_start,
	93	.next = misc_seq_next,
	94	.stop = misc_seq_stop,
	95	.show = misc_seq_show,
	96	};
	97
	98	static int misc_seq_open(struct inode inode, struct file file)
	99	{
	100	return seq_open(file, &misc_seq_ops);
	101	}
	102
62322d25	103	static const struct file_operations misc_proc_fops = {
1da177e4 LT	104	.owner = THIS_MODULE,
	105	.open = misc_seq_open,
	106	.read = seq_read,
	107	.llseek = seq_lseek,
	108	.release = seq_release,
	109	};
	110	#endif
	111
	112	static int misc_open(struct inode * inode, struct file * file)
	113	{
	114	int minor = iminor(inode);
	115	struct miscdevice *c;
	116	int err = -ENODEV;
e84f9e57	117	const struct file_operations *new_fops = NULL;
40b798ef	118
0e82d5b6	119	mutex_lock(&misc_mtx);
898bc282	120
1da177e4 LT	121	list_for_each_entry(c, &misc_list, list) {
1da177e4 LT	122	if (c->minor == minor) {
898bc282	123	new_fops = fops_get(c->fops);
1da177e4 LT	124	break;
	125	}
	126	}
898bc282	127
1da177e4	128	if (!new_fops) {
0e82d5b6	129	mutex_unlock(&misc_mtx);
1da177e4	130	request_module("char-major-%d-%d", MISC_MAJOR, minor);
0e82d5b6	131	mutex_lock(&misc_mtx);
1da177e4 LT	132
	133	list_for_each_entry(c, &misc_list, list) {
	134	if (c->minor == minor) {
	135	new_fops = fops_get(c->fops);
	136	break;
	137	}
	138	}
	139	if (!new_fops)
	140	goto fail;
	141	}
	142
0b509d8d TVB	143	/*
	144	* Place the miscdevice in the file's
	145	* private_data so it can be used by the
	146	* file operations, including f_op->open below
	147	*/
	148	file->private_data = c;
	149
1da177e4	150	err = 0;
e84f9e57	151	replace_fops(file, new_fops);
0b509d8d	152	if (file->f_op->open)
e84f9e57	153	err = file->f_op->open(inode,file);
1da177e4	154	fail:
0e82d5b6	155	mutex_unlock(&misc_mtx);
1da177e4 LT	156	return err;
	157	}
	158
ca8eca68	159	static struct class *misc_class;
1da177e4	160
62322d25	161	static const struct file_operations misc_fops = {
1da177e4 LT	162	.owner = THIS_MODULE,
1da177e4 LT	163	.open = misc_open,
6038f373	164	.llseek = noop_llseek,
1da177e4 LT	165	};
1da177e4 LT	166
1da177e4 LT	167	/**
	168	* misc_register - register a miscellaneous device
	169	* @misc: device structure
898bc282	170	*
1da177e4 LT	171	* Register a miscellaneous device with the kernel. If the minor
	172	* number is set to %MISC_DYNAMIC_MINOR a minor number is assigned
	173	* and placed in the minor field of the structure. For other cases
	174	* the minor number requested is used.
	175	*
	176	* The structure passed is linked into the kernel and may not be
03190c67 MK	177	* destroyed until it has been unregistered. By default, an open()
	178	* syscall to the device sets file->private_data to point to the
	179	* structure. Drivers don't need open in fops for this.
1da177e4 LT	180	*
	181	* A zero is returned on success and a negative errno code for
	182	* failure.
	183	*/
898bc282	184
1da177e4 LT	185	int misc_register(struct miscdevice * misc)
1da177e4 LT	186	{
1da177e4	187	dev_t dev;
7c69ef79	188	int err = 0;
b575f712	189	bool is_dynamic = (misc->minor == MISC_DYNAMIC_MINOR);
1da177e4	190
5d469ec0 NH	191	INIT_LIST_HEAD(&misc->list);
5d469ec0 NH	192
0e82d5b6	193	mutex_lock(&misc_mtx);
1da177e4	194
b575f712	195	if (is_dynamic) {
1f2f38d8 TLSC	196	int i = find_first_zero_bit(misc_minors, DYNAMIC_MINORS);
1f2f38d8 TLSC	197	if (i >= DYNAMIC_MINORS) {
684116ca EW	198	err = -EBUSY;
684116ca EW	199	goto out;
1da177e4	200	}
1f2f38d8 TLSC	201	misc->minor = DYNAMIC_MINORS - i - 1;
1f2f38d8 TLSC	202	set_bit(i, misc_minors);
3c94ce6f DK	203	} else {
	204	struct miscdevice *c;
	205
	206	list_for_each_entry(c, &misc_list, list) {
	207	if (c->minor == misc->minor) {
684116ca EW	208	err = -EBUSY;
684116ca EW	209	goto out;
3c94ce6f DK	210	}
3c94ce6f DK	211	}
1da177e4 LT	212	}
1da177e4 LT	213
1da177e4 LT	214	dev = MKDEV(MISC_MAJOR, misc->minor);
1da177e4 LT	215
bd735995 TI	216	misc->this_device =
	217	device_create_with_groups(misc_class, misc->parent, dev,
	218	misc, misc->groups, "%s", misc->name);
94fbcded	219	if (IS_ERR(misc->this_device)) {
b575f712 VZ	220	if (is_dynamic) {
	221	int i = DYNAMIC_MINORS - misc->minor - 1;
	222
	223	if (i < DYNAMIC_MINORS && i >= 0)
	224	clear_bit(i, misc_minors);
	225	misc->minor = MISC_DYNAMIC_MINOR;
	226	}
94fbcded	227	err = PTR_ERR(misc->this_device);
1da177e4 LT	228	goto out;
	229	}
	230
1da177e4 LT	231	/*
	232	* Add it to the front, so that later devices can "override"
	233	* earlier defaults
	234	*/
	235	list_add(&misc->list, &misc_list);
	236	out:
0e82d5b6	237	mutex_unlock(&misc_mtx);
1da177e4 LT	238	return err;
	239	}
	240
	241	/**
b844eba2	242	* misc_deregister - unregister a miscellaneous device
1da177e4 LT	243	* @misc: device to unregister
	244	*
	245	* Unregister a miscellaneous device that was previously
f368ed60	246	* successfully registered with misc_register().
1da177e4 LT	247	*/
1da177e4 LT	248
f368ed60	249	void misc_deregister(struct miscdevice *misc)
1da177e4	250	{
1f2f38d8	251	int i = DYNAMIC_MINORS - misc->minor - 1;
1da177e4	252
b329becf	253	if (WARN_ON(list_empty(&misc->list)))
f368ed60	254	return;
1da177e4	255
0e82d5b6	256	mutex_lock(&misc_mtx);
1da177e4	257	list_del(&misc->list);
b844eba2	258	device_destroy(misc_class, MKDEV(MISC_MAJOR, misc->minor));
4ae717da	259	if (i < DYNAMIC_MINORS && i >= 0)
1f2f38d8	260	clear_bit(i, misc_minors);
0e82d5b6	261	mutex_unlock(&misc_mtx);
1da177e4 LT	262	}
	263
	264	EXPORT_SYMBOL(misc_register);
b844eba2	265	EXPORT_SYMBOL(misc_deregister);
1da177e4	266
2c9ede55	267	static char misc_devnode(struct device dev, umode_t *mode)
d4056405 KS	268	{
	269	struct miscdevice *c = dev_get_drvdata(dev);
	270
e454cea2 KS	271	if (mode && c->mode)
	272	*mode = c->mode;
	273	if (c->nodename)
	274	return kstrdup(c->nodename, GFP_KERNEL);
d4056405 KS	275	return NULL;
	276	}
	277
1da177e4 LT	278	static int __init misc_init(void)
1da177e4 LT	279	{
1b502217	280	int err;
1037b278	281	struct proc_dir_entry *ret;
1da177e4	282
1037b278	283	ret = proc_create("misc", 0, NULL, &misc_proc_fops);
ca8eca68	284	misc_class = class_create(THIS_MODULE, "misc");
1b502217	285	err = PTR_ERR(misc_class);
1da177e4	286	if (IS_ERR(misc_class))
1b502217	287	goto fail_remove;
573fc113	288
1b502217 DL	289	err = -EIO;
	290	if (register_chrdev(MISC_MAJOR,"misc",&misc_fops))
	291	goto fail_printk;
e454cea2	292	misc_class->devnode = misc_devnode;
1da177e4	293	return 0;
1b502217 DL	294
	295	fail_printk:
	296	printk("unable to get major %d for misc devices\n", MISC_MAJOR);
	297	class_destroy(misc_class);
	298	fail_remove:
1037b278 SM	299	if (ret)
1037b278 SM	300	remove_proc_entry("misc", NULL);
1b502217	301	return err;
1da177e4 LT	302	}
1da177e4 LT	303	subsys_initcall(misc_init);