[linux-2.6-block.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/config.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/proc_fs.h>
#include <linux/seq_file.h>
#include <linux/devfs_fs_kernel.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 DECLARE_MUTEX(misc_sem);

/*
 * 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;

	down(&misc_sem);
	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)
{
	up(&misc_sem);
}

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 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;
	struct file_operations *old_fops, *new_fops = NULL;
	
	down(&misc_sem);
	
	list_for_each_entry(c, &misc_list, list) {
		if (c->minor == minor) {
			new_fops = fops_get(c->fops);		
			break;
		}
	}
		
	if (!new_fops) {
		up(&misc_sem);
		request_module("char-major-%d-%d", MISC_MAJOR, minor);
		down(&misc_sem);

		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:
	up(&misc_sem);
	return err;
}

/* 
 * TODO for 2.7:
 *  - add a struct kref to struct miscdevice and make all usages of
 *    them dynamic.
 */
static struct class *misc_class;

static 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;

	down(&misc_sem);
	list_for_each_entry(c, &misc_list, list) {
		if (c->minor == misc->minor) {
			up(&misc_sem);
			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) {
			up(&misc_sem);
			return -EBUSY;
		}
		misc->minor = i;
	}

	if (misc->minor < DYNAMIC_MINORS)
		misc_minors[misc->minor >> 3] |= 1 << (misc->minor & 7);
	if (misc->devfs_name[0] == '\0') {
		snprintf(misc->devfs_name, sizeof(misc->devfs_name),
				"misc/%s", misc->name);
	}
	dev = MKDEV(MISC_MAJOR, misc->minor);

	misc->class = class_device_create(misc_class, dev, misc->dev,
					  "%s", misc->name);
	if (IS_ERR(misc->class)) {
		err = PTR_ERR(misc->class);
		goto out;
	}

	err = devfs_mk_cdev(dev, S_IFCHR|S_IRUSR|S_IWUSR|S_IRGRP, 
			    misc->devfs_name);
	if (err) {
		class_device_destroy(misc_class, dev);
		goto out;
	}

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

	down(&misc_sem);
	list_del(&misc->list);
	class_device_destroy(misc_class, MKDEV(MISC_MAJOR, misc->minor));
	devfs_remove(misc->devfs_name);
	if (i < DYNAMIC_MINORS && i>0) {
		misc_minors[i>>3] &= ~(1 << (misc->minor & 7));
	}
	up(&misc_sem);
	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>
	37	#include <linux/config.h>
	38
	39	#include <linux/fs.h>
	40	#include <linux/errno.h>
	41	#include <linux/miscdevice.h>
	42	#include <linux/kernel.h>
	43	#include <linux/major.h>
	44	#include <linux/slab.h>
	45	#include <linux/proc_fs.h>
	46	#include <linux/seq_file.h>
	47	#include <linux/devfs_fs_kernel.h>
	48	#include <linux/stat.h>
	49	#include <linux/init.h>
	50	#include <linux/device.h>
	51	#include <linux/tty.h>
	52	#include <linux/kmod.h>
	53
	54	/*
	55	* Head entry for the doubly linked miscdevice list
	56	*/
	57	static LIST_HEAD(misc_list);
	58	static DECLARE_MUTEX(misc_sem);
	59
	60	/*
	61	* Assigned numbers, used for dynamic minors
	62	*/
	63	#define DYNAMIC_MINORS 64 /* like dynamic majors */
	64	static unsigned char misc_minors[DYNAMIC_MINORS / 8];
65
1da177e4	66	extern int pmu_device_init(void);
1da177e4 LT	67
	68	#ifdef CONFIG_PROC_FS
	69	static void misc_seq_start(struct seq_file seq, loff_t *pos)
	70	{
	71	struct miscdevice *p;
	72	loff_t off = 0;
	73
	74	down(&misc_sem);
	75	list_for_each_entry(p, &misc_list, list) {
	76	if (*pos == off++)
	77	return p;
	78	}
	79	return NULL;
	80	}
	81
	82	static void misc_seq_next(struct seq_file seq, void v, loff_t pos)
	83	{
	84	struct list_head n = ((struct miscdevice )v)->list.next;
	85
	86	++*pos;
	87
	88	return (n != &misc_list) ? list_entry(n, struct miscdevice, list)
	89	: NULL;
	90	}
	91
	92	static void misc_seq_stop(struct seq_file seq, void v)
	93	{
	94	up(&misc_sem);
	95	}
	96
	97	static int misc_seq_show(struct seq_file seq, void v)
	98	{
	99	const struct miscdevice *p = v;
	100
	101	seq_printf(seq, "%3i %s\n", p->minor, p->name ? p->name : "");
	102	return 0;
	103	}
	104
	105
	106	static struct seq_operations misc_seq_ops = {
	107	.start = misc_seq_start,
	108	.next = misc_seq_next,
	109	.stop = misc_seq_stop,
	110	.show = misc_seq_show,
	111	};
	112
	113	static int misc_seq_open(struct inode inode, struct file file)
	114	{
	115	return seq_open(file, &misc_seq_ops);
	116	}
	117
	118	static struct file_operations misc_proc_fops = {
	119	.owner = THIS_MODULE,
	120	.open = misc_seq_open,
	121	.read = seq_read,
	122	.llseek = seq_lseek,
	123	.release = seq_release,
	124	};
	125	#endif
	126
	127	static int misc_open(struct inode * inode, struct file * file)
	128	{
	129	int minor = iminor(inode);
	130	struct miscdevice *c;
131	int err = -ENODEV;
132	struct file_operations old_fops, new_fops = NULL;
133
134	down(&misc_sem);
135
136	list_for_each_entry(c, &misc_list, list) {
137	if (c->minor == minor) {
138	new_fops = fops_get(c->fops);
139	break;
140	}
141	}
142
143	if (!new_fops) {
144	up(&misc_sem);
145	request_module("char-major-%d-%d", MISC_MAJOR, minor);
146	down(&misc_sem);
147
148	list_for_each_entry(c, &misc_list, list) {
149	if (c->minor == minor) {
150	new_fops = fops_get(c->fops);
151	break;
152	}
153	}
154	if (!new_fops)
155	goto fail;
156	}
157
158	err = 0;
159	old_fops = file->f_op;
160	file->f_op = new_fops;
161	if (file->f_op->open) {
162	err=file->f_op->open(inode,file);
163	if (err) {
164	fops_put(file->f_op);
165	file->f_op = fops_get(old_fops);
166	}
167	}
168	fops_put(old_fops);
169	fail:
170	up(&misc_sem);
171	return err;
172	}
173
174	/*
175	* TODO for 2.7:
ca8eca68	176	* - add a struct kref to struct miscdevice and make all usages of
1da177e4 LT	177	* them dynamic.
1da177e4 LT	178	*/
ca8eca68	179	static struct class *misc_class;
1da177e4 LT	180
	181	static struct file_operations misc_fops = {
	182	.owner = THIS_MODULE,
	183	.open = misc_open,
	184	};
	185
	186
	187	/**
	188	* misc_register - register a miscellaneous device
	189	* @misc: device structure
	190	*
	191	* Register a miscellaneous device with the kernel. If the minor
	192	* number is set to %MISC_DYNAMIC_MINOR a minor number is assigned
	193	* and placed in the minor field of the structure. For other cases
	194	* the minor number requested is used.
	195	*
	196	* The structure passed is linked into the kernel and may not be
	197	* destroyed until it has been unregistered.
	198	*
	199	* A zero is returned on success and a negative errno code for
	200	* failure.
	201	*/
	202
	203	int misc_register(struct miscdevice * misc)
	204	{
	205	struct miscdevice *c;
	206	dev_t dev;
	207	int err;
	208
	209	down(&misc_sem);
	210	list_for_each_entry(c, &misc_list, list) {
	211	if (c->minor == misc->minor) {
	212	up(&misc_sem);
	213	return -EBUSY;
	214	}
	215	}
	216
	217	if (misc->minor == MISC_DYNAMIC_MINOR) {
	218	int i = DYNAMIC_MINORS;
	219	while (--i >= 0)
	220	if ( (misc_minors[i>>3] & (1 << (i&7))) == 0)
	221	break;
	222	if (i<0) {
	223	up(&misc_sem);
	224	return -EBUSY;
	225	}
	226	misc->minor = i;
	227	}
	228
	229	if (misc->minor < DYNAMIC_MINORS)
	230	misc_minors[misc->minor >> 3] \|= 1 << (misc->minor & 7);
	231	if (misc->devfs_name[0] == '\0') {
	232	snprintf(misc->devfs_name, sizeof(misc->devfs_name),
	233	"misc/%s", misc->name);
	234	}
	235	dev = MKDEV(MISC_MAJOR, misc->minor);
	236
ca8eca68	237	misc->class = class_device_create(misc_class, dev, misc->dev,
ca8eca68	238	"%s", misc->name);
1da177e4 LT	239	if (IS_ERR(misc->class)) {
	240	err = PTR_ERR(misc->class);
	241	goto out;
	242	}
	243
	244	err = devfs_mk_cdev(dev, S_IFCHR\|S_IRUSR\|S_IWUSR\|S_IRGRP,
	245	misc->devfs_name);
	246	if (err) {
ca8eca68	247	class_device_destroy(misc_class, dev);
1da177e4 LT	248	goto out;
	249	}
	250
	251	/*
	252	* Add it to the front, so that later devices can "override"
	253	* earlier defaults
	254	*/
	255	list_add(&misc->list, &misc_list);
	256	out:
	257	up(&misc_sem);
	258	return err;
	259	}
	260
	261	/**
	262	* misc_deregister - unregister a miscellaneous device
	263	* @misc: device to unregister
	264	*
	265	* Unregister a miscellaneous device that was previously
	266	* successfully registered with misc_register(). Success
	267	* is indicated by a zero return, a negative errno code
	268	* indicates an error.
	269	*/
	270
	271	int misc_deregister(struct miscdevice * misc)
	272	{
	273	int i = misc->minor;
	274
	275	if (list_empty(&misc->list))
	276	return -EINVAL;
	277
	278	down(&misc_sem);
	279	list_del(&misc->list);
ca8eca68	280	class_device_destroy(misc_class, MKDEV(MISC_MAJOR, misc->minor));
1da177e4 LT	281	devfs_remove(misc->devfs_name);
	282	if (i < DYNAMIC_MINORS && i>0) {
	283	misc_minors[i>>3] &= ~(1 << (misc->minor & 7));
	284	}
	285	up(&misc_sem);
	286	return 0;
	287	}
	288
	289	EXPORT_SYMBOL(misc_register);
	290	EXPORT_SYMBOL(misc_deregister);
	291
	292	static int __init misc_init(void)
	293	{
	294	#ifdef CONFIG_PROC_FS
	295	struct proc_dir_entry *ent;
	296
	297	ent = create_proc_entry("misc", 0, NULL);
	298	if (ent)
	299	ent->proc_fops = &misc_proc_fops;
	300	#endif
ca8eca68	301	misc_class = class_create(THIS_MODULE, "misc");
1da177e4 LT	302	if (IS_ERR(misc_class))
1da177e4 LT	303	return PTR_ERR(misc_class);
573fc113	304
1da177e4 LT	305	if (register_chrdev(MISC_MAJOR,"misc",&misc_fops)) {
	306	printk("unable to get major %d for misc devices\n",
	307	MISC_MAJOR);
ca8eca68	308	class_destroy(misc_class);
1da177e4 LT	309	return -EIO;
	310	}
	311	return 0;
	312	}
	313	subsys_initcall(misc_init);