[mirror_ubuntu-bionic-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/slab.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>

/*
 * 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 unsigned char misc_minors[DYNAMIC_MINORS / 8];

extern int pmu_device_init(void);

#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 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 *old_fops, *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;
	}

	err = 0;
	old_fops = file->f_op;
	file->f_op = new_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);
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,
};


/**
 *	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.
 *
 *	A zero is returned on success and a negative errno code for
 *	failure.
 */
 
int misc_register(struct miscdevice * misc)
{
	struct miscdevice *c;
	dev_t dev;
	int err = 0;

	INIT_LIST_HEAD(&misc->list);

	mutex_lock(&misc_mtx);
	list_for_each_entry(c, &misc_list, list) {
		if (c->minor == misc->minor) {
			mutex_unlock(&misc_mtx);
			return -EBUSY;
		}
	}

	if (misc->minor == MISC_DYNAMIC_MINOR) {
		int i = DYNAMIC_MINORS;
		while (--i >= 0)
			if ( (misc_minors[i>>3] & (1 << (i&7))) == 0)
				break;
		if (i<0) {
			mutex_unlock(&misc_mtx);
			return -EBUSY;
		}
		misc->minor = i;
	}

	if (misc->minor < DYNAMIC_MINORS)
		misc_minors[misc->minor >> 3] |= 1 << (misc->minor & 7);
	dev = MKDEV(MISC_MAJOR, misc->minor);

	misc->this_device = device_create(misc_class, misc->parent, dev,
					  "%s", misc->name);
	if (IS_ERR(misc->this_device)) {
		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(). Success
 *	is indicated by a zero return, a negative errno code
 *	indicates an error.
 */

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

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

	mutex_lock(&misc_mtx);
	list_del(&misc->list);
	device_destroy(misc_class, MKDEV(MISC_MAJOR, misc->minor));
	if (i < DYNAMIC_MINORS && i>0) {
		misc_minors[i>>3] &= ~(1 << (misc->minor & 7));
	}
	mutex_unlock(&misc_mtx);
	return 0;
}

EXPORT_SYMBOL(misc_register);
EXPORT_SYMBOL(misc_deregister);

static int __init misc_init(void)
{
	int err;

#ifdef CONFIG_PROC_FS
	proc_create("misc", 0, NULL, &misc_proc_fops);
#endif
	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;
	return 0;

fail_printk:
	printk("unable to get major %d for misc devices\n", MISC_MAJOR);
	class_destroy(misc_class);
fail_remove:
	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>
	43	#include <linux/slab.h>
0e82d5b6	44	#include <linux/mutex.h>
1da177e4 LT	45	#include <linux/proc_fs.h>
1da177e4 LT	46	#include <linux/seq_file.h>
1da177e4 LT	47	#include <linux/stat.h>
	48	#include <linux/init.h>
	49	#include <linux/device.h>
	50	#include <linux/tty.h>
	51	#include <linux/kmod.h>
	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 */
	63	static unsigned char misc_minors[DYNAMIC_MINORS / 8];
	64
1da177e4	65	extern int pmu_device_init(void);
1da177e4 LT	66
	67	#ifdef CONFIG_PROC_FS
	68	static void misc_seq_start(struct seq_file seq, loff_t *pos)
	69	{
0e82d5b6	70	mutex_lock(&misc_mtx);
46c65b71	71	return seq_list_start(&misc_list, *pos);
1da177e4 LT	72	}
	73
	74	static void misc_seq_next(struct seq_file seq, void v, loff_t pos)
	75	{
46c65b71	76	return seq_list_next(v, &misc_list, pos);
1da177e4 LT	77	}
	78
	79	static void misc_seq_stop(struct seq_file seq, void v)
	80	{
0e82d5b6	81	mutex_unlock(&misc_mtx);
1da177e4 LT	82	}
	83
	84	static int misc_seq_show(struct seq_file seq, void v)
	85	{
46c65b71	86	const struct miscdevice *p = list_entry(v, struct miscdevice, list);
1da177e4 LT	87
	88	seq_printf(seq, "%3i %s\n", p->minor, p->name ? p->name : "");
	89	return 0;
	90	}
	91
	92
	93	static struct seq_operations misc_seq_ops = {
	94	.start = misc_seq_start,
	95	.next = misc_seq_next,
	96	.stop = misc_seq_stop,
	97	.show = misc_seq_show,
	98	};
	99
	100	static int misc_seq_open(struct inode inode, struct file file)
	101	{
	102	return seq_open(file, &misc_seq_ops);
	103	}
	104
62322d25	105	static const struct file_operations misc_proc_fops = {
1da177e4 LT	106	.owner = THIS_MODULE,
	107	.open = misc_seq_open,
	108	.read = seq_read,
	109	.llseek = seq_lseek,
	110	.release = seq_release,
	111	};
	112	#endif
	113
	114	static int misc_open(struct inode * inode, struct file * file)
	115	{
	116	int minor = iminor(inode);
	117	struct miscdevice *c;
	118	int err = -ENODEV;
99ac48f5	119	const struct file_operations old_fops, new_fops = NULL;
1da177e4	120
0e82d5b6	121	mutex_lock(&misc_mtx);
1da177e4 LT	122
	123	list_for_each_entry(c, &misc_list, list) {
	124	if (c->minor == minor) {
	125	new_fops = fops_get(c->fops);
	126	break;
	127	}
	128	}
	129
	130	if (!new_fops) {
0e82d5b6	131	mutex_unlock(&misc_mtx);
1da177e4	132	request_module("char-major-%d-%d", MISC_MAJOR, minor);
0e82d5b6	133	mutex_lock(&misc_mtx);
1da177e4 LT	134
	135	list_for_each_entry(c, &misc_list, list) {
	136	if (c->minor == minor) {
	137	new_fops = fops_get(c->fops);
	138	break;
	139	}
	140	}
	141	if (!new_fops)
	142	goto fail;
	143	}
	144
	145	err = 0;
	146	old_fops = file->f_op;
	147	file->f_op = new_fops;
	148	if (file->f_op->open) {
	149	err=file->f_op->open(inode,file);
	150	if (err) {
	151	fops_put(file->f_op);
	152	file->f_op = fops_get(old_fops);
	153	}
	154	}
	155	fops_put(old_fops);
	156	fail:
0e82d5b6	157	mutex_unlock(&misc_mtx);
1da177e4 LT	158	return err;
	159	}
	160
ca8eca68	161	static struct class *misc_class;
1da177e4	162
62322d25	163	static const struct file_operations misc_fops = {
1da177e4 LT	164	.owner = THIS_MODULE,
	165	.open = misc_open,
	166	};
	167
	168
	169	/**
	170	* misc_register - register a miscellaneous device
	171	* @misc: device structure
	172	*
	173	* Register a miscellaneous device with the kernel. If the minor
	174	* number is set to %MISC_DYNAMIC_MINOR a minor number is assigned
	175	* and placed in the minor field of the structure. For other cases
	176	* the minor number requested is used.
	177	*
	178	* The structure passed is linked into the kernel and may not be
	179	* destroyed until it has been unregistered.
	180	*
	181	* A zero is returned on success and a negative errno code for
	182	* failure.
	183	*/
	184
	185	int misc_register(struct miscdevice * misc)
	186	{
	187	struct miscdevice *c;
	188	dev_t dev;
7c69ef79	189	int err = 0;
1da177e4	190
5d469ec0 NH	191	INIT_LIST_HEAD(&misc->list);
5d469ec0 NH	192
0e82d5b6	193	mutex_lock(&misc_mtx);
1da177e4 LT	194	list_for_each_entry(c, &misc_list, list) {
1da177e4 LT	195	if (c->minor == misc->minor) {
0e82d5b6	196	mutex_unlock(&misc_mtx);
1da177e4 LT	197	return -EBUSY;
	198	}
	199	}
	200
	201	if (misc->minor == MISC_DYNAMIC_MINOR) {
	202	int i = DYNAMIC_MINORS;
	203	while (--i >= 0)
	204	if ( (misc_minors[i>>3] & (1 << (i&7))) == 0)
	205	break;
	206	if (i<0) {
0e82d5b6	207	mutex_unlock(&misc_mtx);
1da177e4 LT	208	return -EBUSY;
	209	}
	210	misc->minor = i;
	211	}
	212
	213	if (misc->minor < DYNAMIC_MINORS)
	214	misc_minors[misc->minor >> 3] \|= 1 << (misc->minor & 7);
1da177e4 LT	215	dev = MKDEV(MISC_MAJOR, misc->minor);
1da177e4 LT	216
94fbcded	217	misc->this_device = device_create(misc_class, misc->parent, dev,
ca8eca68	218	"%s", misc->name);
94fbcded GKH	219	if (IS_ERR(misc->this_device)) {
94fbcded GKH	220	err = PTR_ERR(misc->this_device);
1da177e4 LT	221	goto out;
	222	}
	223
1da177e4 LT	224	/*
	225	* Add it to the front, so that later devices can "override"
	226	* earlier defaults
	227	*/
	228	list_add(&misc->list, &misc_list);
	229	out:
0e82d5b6	230	mutex_unlock(&misc_mtx);
1da177e4 LT	231	return err;
	232	}
	233
	234	/**
b844eba2	235	* misc_deregister - unregister a miscellaneous device
1da177e4 LT	236	* @misc: device to unregister
	237	*
	238	* Unregister a miscellaneous device that was previously
	239	* successfully registered with misc_register(). Success
	240	* is indicated by a zero return, a negative errno code
	241	* indicates an error.
	242	*/
	243
b844eba2	244	int misc_deregister(struct miscdevice *misc)
1da177e4 LT	245	{
	246	int i = misc->minor;
	247
	248	if (list_empty(&misc->list))
	249	return -EINVAL;
	250
0e82d5b6	251	mutex_lock(&misc_mtx);
1da177e4	252	list_del(&misc->list);
b844eba2	253	device_destroy(misc_class, MKDEV(MISC_MAJOR, misc->minor));
1da177e4 LT	254	if (i < DYNAMIC_MINORS && i>0) {
	255	misc_minors[i>>3] &= ~(1 << (misc->minor & 7));
	256	}
0e82d5b6	257	mutex_unlock(&misc_mtx);
1da177e4 LT	258	return 0;
	259	}
	260
	261	EXPORT_SYMBOL(misc_register);
b844eba2	262	EXPORT_SYMBOL(misc_deregister);
1da177e4 LT	263
	264	static int __init misc_init(void)
	265	{
1b502217	266	int err;
1da177e4	267
1b502217 DL	268	#ifdef CONFIG_PROC_FS
1b502217 DL	269	proc_create("misc", 0, NULL, &misc_proc_fops);
1da177e4	270	#endif
ca8eca68	271	misc_class = class_create(THIS_MODULE, "misc");
1b502217	272	err = PTR_ERR(misc_class);
1da177e4	273	if (IS_ERR(misc_class))
1b502217	274	goto fail_remove;
573fc113	275
1b502217 DL	276	err = -EIO;
	277	if (register_chrdev(MISC_MAJOR,"misc",&misc_fops))
	278	goto fail_printk;
1da177e4	279	return 0;
1b502217 DL	280
	281	fail_printk:
	282	printk("unable to get major %d for misc devices\n", MISC_MAJOR);
	283	class_destroy(misc_class);
	284	fail_remove:
	285	remove_proc_entry("misc", NULL);
	286	return err;
1da177e4 LT	287	}
1da177e4 LT	288	subsys_initcall(misc_init);