[deliverable/linux.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)
{
	struct miscdevice *p;
	loff_t off = 0;

	mutex_lock(&misc_mtx);
	list_for_each_entry(p, &misc_list, list) {
		if (*pos == off++) 
			return p;
	}
	return NULL;
}

static void *misc_seq_next(struct seq_file *seq, void *v, loff_t *pos)
{
	struct list_head *n = ((struct miscdevice *)v)->list.next;

	++*pos;

	return (n != &misc_list) ? list_entry(n, struct miscdevice, list)
		 : NULL;
}

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 = v;

	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)
{
#ifdef CONFIG_PROC_FS
	struct proc_dir_entry *ent;

	ent = create_proc_entry("misc", 0, NULL);
	if (ent)
		ent->proc_fops = &misc_proc_fops;
#endif
	misc_class = class_create(THIS_MODULE, "misc");
	if (IS_ERR(misc_class))
		return PTR_ERR(misc_class);

	if (register_chrdev(MISC_MAJOR,"misc",&misc_fops)) {
		printk("unable to get major %d for misc devices\n",
		       MISC_MAJOR);
		class_destroy(misc_class);
		return -EIO;
	}
	return 0;
}
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	{
	70	struct miscdevice *p;
	71	loff_t off = 0;
	72
0e82d5b6	73	mutex_lock(&misc_mtx);
1da177e4 LT	74	list_for_each_entry(p, &misc_list, list) {
	75	if (*pos == off++)
	76	return p;
	77	}
	78	return NULL;
	79	}
	80
	81	static void misc_seq_next(struct seq_file seq, void v, loff_t pos)
	82	{
	83	struct list_head n = ((struct miscdevice )v)->list.next;
	84
	85	++*pos;
	86
	87	return (n != &misc_list) ? list_entry(n, struct miscdevice, list)
	88	: NULL;
	89	}
	90
	91	static void misc_seq_stop(struct seq_file seq, void v)
	92	{
0e82d5b6	93	mutex_unlock(&misc_mtx);
1da177e4 LT	94	}
	95
	96	static int misc_seq_show(struct seq_file seq, void v)
	97	{
	98	const struct miscdevice *p = v;
	99
	100	seq_printf(seq, "%3i %s\n", p->minor, p->name ? p->name : "");
	101	return 0;
	102	}
	103
	104
	105	static struct seq_operations misc_seq_ops = {
	106	.start = misc_seq_start,
	107	.next = misc_seq_next,
	108	.stop = misc_seq_stop,
	109	.show = misc_seq_show,
	110	};
	111
	112	static int misc_seq_open(struct inode inode, struct file file)
	113	{
	114	return seq_open(file, &misc_seq_ops);
	115	}
	116
62322d25	117	static const struct file_operations misc_proc_fops = {
1da177e4 LT	118	.owner = THIS_MODULE,
	119	.open = misc_seq_open,
	120	.read = seq_read,
	121	.llseek = seq_lseek,
	122	.release = seq_release,
	123	};
	124	#endif
	125
	126	static int misc_open(struct inode * inode, struct file * file)
	127	{
	128	int minor = iminor(inode);
	129	struct miscdevice *c;
	130	int err = -ENODEV;
99ac48f5	131	const struct file_operations old_fops, new_fops = NULL;
1da177e4	132
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
	142	if (!new_fops) {
0e82d5b6	143	mutex_unlock(&misc_mtx);
1da177e4	144	request_module("char-major-%d-%d", MISC_MAJOR, minor);
0e82d5b6	145	mutex_lock(&misc_mtx);
1da177e4 LT	146
	147	list_for_each_entry(c, &misc_list, list) {
	148	if (c->minor == minor) {
	149	new_fops = fops_get(c->fops);
	150	break;
	151	}
	152	}
	153	if (!new_fops)
	154	goto fail;
	155	}
	156
	157	err = 0;
	158	old_fops = file->f_op;
	159	file->f_op = new_fops;
	160	if (file->f_op->open) {
	161	err=file->f_op->open(inode,file);
	162	if (err) {
	163	fops_put(file->f_op);
	164	file->f_op = fops_get(old_fops);
	165	}
	166	}
	167	fops_put(old_fops);
	168	fail:
0e82d5b6	169	mutex_unlock(&misc_mtx);
1da177e4 LT	170	return err;
	171	}
	172
ca8eca68	173	static struct class *misc_class;
1da177e4	174
62322d25	175	static const struct file_operations misc_fops = {
1da177e4 LT	176	.owner = THIS_MODULE,
	177	.open = misc_open,
	178	};
	179
	180
	181	/**
	182	* misc_register - register a miscellaneous device
	183	* @misc: device structure
	184	*
	185	* Register a miscellaneous device with the kernel. If the minor
	186	* number is set to %MISC_DYNAMIC_MINOR a minor number is assigned
	187	* and placed in the minor field of the structure. For other cases
	188	* the minor number requested is used.
	189	*
	190	* The structure passed is linked into the kernel and may not be
	191	* destroyed until it has been unregistered.
	192	*
	193	* A zero is returned on success and a negative errno code for
	194	* failure.
	195	*/
	196
	197	int misc_register(struct miscdevice * misc)
	198	{
	199	struct miscdevice *c;
	200	dev_t dev;
7c69ef79	201	int err = 0;
1da177e4	202
5d469ec0 NH	203	INIT_LIST_HEAD(&misc->list);
5d469ec0 NH	204
0e82d5b6	205	mutex_lock(&misc_mtx);
1da177e4 LT	206	list_for_each_entry(c, &misc_list, list) {
1da177e4 LT	207	if (c->minor == misc->minor) {
0e82d5b6	208	mutex_unlock(&misc_mtx);
1da177e4 LT	209	return -EBUSY;
	210	}
	211	}
	212
	213	if (misc->minor == MISC_DYNAMIC_MINOR) {
	214	int i = DYNAMIC_MINORS;
	215	while (--i >= 0)
	216	if ( (misc_minors[i>>3] & (1 << (i&7))) == 0)
	217	break;
	218	if (i<0) {
0e82d5b6	219	mutex_unlock(&misc_mtx);
1da177e4 LT	220	return -EBUSY;
	221	}
	222	misc->minor = i;
	223	}
	224
	225	if (misc->minor < DYNAMIC_MINORS)
	226	misc_minors[misc->minor >> 3] \|= 1 << (misc->minor & 7);
1da177e4 LT	227	dev = MKDEV(MISC_MAJOR, misc->minor);
1da177e4 LT	228
94fbcded	229	misc->this_device = device_create(misc_class, misc->parent, dev,
ca8eca68	230	"%s", misc->name);
94fbcded GKH	231	if (IS_ERR(misc->this_device)) {
94fbcded GKH	232	err = PTR_ERR(misc->this_device);
1da177e4 LT	233	goto out;
	234	}
	235
1da177e4 LT	236	/*
	237	* Add it to the front, so that later devices can "override"
	238	* earlier defaults
	239	*/
	240	list_add(&misc->list, &misc_list);
	241	out:
0e82d5b6	242	mutex_unlock(&misc_mtx);
1da177e4 LT	243	return err;
	244	}
	245
	246	/**
	247	* misc_deregister - unregister a miscellaneous device
	248	* @misc: device to unregister
	249	*
	250	* Unregister a miscellaneous device that was previously
	251	* successfully registered with misc_register(). Success
	252	* is indicated by a zero return, a negative errno code
	253	* indicates an error.
	254	*/
	255
	256	int misc_deregister(struct miscdevice * misc)
	257	{
	258	int i = misc->minor;
	259
	260	if (list_empty(&misc->list))
	261	return -EINVAL;
	262
0e82d5b6	263	mutex_lock(&misc_mtx);
1da177e4	264	list_del(&misc->list);
94fbcded	265	device_destroy(misc_class, MKDEV(MISC_MAJOR, misc->minor));
1da177e4 LT	266	if (i < DYNAMIC_MINORS && i>0) {
	267	misc_minors[i>>3] &= ~(1 << (misc->minor & 7));
	268	}
0e82d5b6	269	mutex_unlock(&misc_mtx);
1da177e4 LT	270	return 0;
	271	}
	272
	273	EXPORT_SYMBOL(misc_register);
	274	EXPORT_SYMBOL(misc_deregister);
	275
	276	static int __init misc_init(void)
	277	{
	278	#ifdef CONFIG_PROC_FS
	279	struct proc_dir_entry *ent;
	280
	281	ent = create_proc_entry("misc", 0, NULL);
	282	if (ent)
	283	ent->proc_fops = &misc_proc_fops;
	284	#endif
ca8eca68	285	misc_class = class_create(THIS_MODULE, "misc");
1da177e4 LT	286	if (IS_ERR(misc_class))
1da177e4 LT	287	return PTR_ERR(misc_class);
573fc113	288
1da177e4 LT	289	if (register_chrdev(MISC_MAJOR,"misc",&misc_fops)) {
	290	printk("unable to get major %d for misc devices\n",
	291	MISC_MAJOR);
ca8eca68	292	class_destroy(misc_class);
1da177e4 LT	293	return -EIO;
	294	}
	295	return 0;
	296	}
	297	subsys_initcall(misc_init);