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Linus Torvalds1da177e2005-04-16 15:20:36 -07001/*
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>
Linus Torvalds1da177e2005-04-16 15:20:36 -070037
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>
Matthias Kaehlcke0e82d5b2007-05-08 00:32:08 -070044#include <linux/mutex.h>
Linus Torvalds1da177e2005-04-16 15:20:36 -070045#include <linux/proc_fs.h>
46#include <linux/seq_file.h>
Linus Torvalds1da177e2005-04-16 15:20:36 -070047#include <linux/stat.h>
48#include <linux/init.h>
49#include <linux/device.h>
50#include <linux/tty.h>
51#include <linux/kmod.h>
Jonathan Corbet309c4552008-05-15 11:07:52 -060052#include <linux/smp_lock.h>
Linus Torvalds1da177e2005-04-16 15:20:36 -070053
54/*
55 * Head entry for the doubly linked miscdevice list
56 */
57static LIST_HEAD(misc_list);
Matthias Kaehlcke0e82d5b2007-05-08 00:32:08 -070058static DEFINE_MUTEX(misc_mtx);
Linus Torvalds1da177e2005-04-16 15:20:36 -070059
60/*
61 * Assigned numbers, used for dynamic minors
62 */
63#define DYNAMIC_MINORS 64 /* like dynamic majors */
64static unsigned char misc_minors[DYNAMIC_MINORS / 8];
65
Linus Torvalds1da177e2005-04-16 15:20:36 -070066extern int pmu_device_init(void);
Linus Torvalds1da177e2005-04-16 15:20:36 -070067
68#ifdef CONFIG_PROC_FS
69static void *misc_seq_start(struct seq_file *seq, loff_t *pos)
70{
Matthias Kaehlcke0e82d5b2007-05-08 00:32:08 -070071 mutex_lock(&misc_mtx);
Pavel Emelianov46c65b72007-07-15 23:39:53 -070072 return seq_list_start(&misc_list, *pos);
Linus Torvalds1da177e2005-04-16 15:20:36 -070073}
74
75static void *misc_seq_next(struct seq_file *seq, void *v, loff_t *pos)
76{
Pavel Emelianov46c65b72007-07-15 23:39:53 -070077 return seq_list_next(v, &misc_list, pos);
Linus Torvalds1da177e2005-04-16 15:20:36 -070078}
79
80static void misc_seq_stop(struct seq_file *seq, void *v)
81{
Matthias Kaehlcke0e82d5b2007-05-08 00:32:08 -070082 mutex_unlock(&misc_mtx);
Linus Torvalds1da177e2005-04-16 15:20:36 -070083}
84
85static int misc_seq_show(struct seq_file *seq, void *v)
86{
Pavel Emelianov46c65b72007-07-15 23:39:53 -070087 const struct miscdevice *p = list_entry(v, struct miscdevice, list);
Linus Torvalds1da177e2005-04-16 15:20:36 -070088
89 seq_printf(seq, "%3i %s\n", p->minor, p->name ? p->name : "");
90 return 0;
91}
92
93
94static struct seq_operations misc_seq_ops = {
95 .start = misc_seq_start,
96 .next = misc_seq_next,
97 .stop = misc_seq_stop,
98 .show = misc_seq_show,
99};
100
101static int misc_seq_open(struct inode *inode, struct file *file)
102{
103 return seq_open(file, &misc_seq_ops);
104}
105
Arjan van de Ven62322d22006-07-03 00:24:21 -0700106static const struct file_operations misc_proc_fops = {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700107 .owner = THIS_MODULE,
108 .open = misc_seq_open,
109 .read = seq_read,
110 .llseek = seq_lseek,
111 .release = seq_release,
112};
113#endif
114
115static int misc_open(struct inode * inode, struct file * file)
116{
117 int minor = iminor(inode);
118 struct miscdevice *c;
119 int err = -ENODEV;
Arjan van de Ven99ac48f2006-03-28 01:56:41 -0800120 const struct file_operations *old_fops, *new_fops = NULL;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700121
Jonathan Corbet309c4552008-05-15 11:07:52 -0600122 lock_kernel();
Matthias Kaehlcke0e82d5b2007-05-08 00:32:08 -0700123 mutex_lock(&misc_mtx);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700124
125 list_for_each_entry(c, &misc_list, list) {
126 if (c->minor == minor) {
127 new_fops = fops_get(c->fops);
128 break;
129 }
130 }
131
132 if (!new_fops) {
Matthias Kaehlcke0e82d5b2007-05-08 00:32:08 -0700133 mutex_unlock(&misc_mtx);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700134 request_module("char-major-%d-%d", MISC_MAJOR, minor);
Matthias Kaehlcke0e82d5b2007-05-08 00:32:08 -0700135 mutex_lock(&misc_mtx);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700136
137 list_for_each_entry(c, &misc_list, list) {
138 if (c->minor == minor) {
139 new_fops = fops_get(c->fops);
140 break;
141 }
142 }
143 if (!new_fops)
144 goto fail;
145 }
146
147 err = 0;
148 old_fops = file->f_op;
149 file->f_op = new_fops;
150 if (file->f_op->open) {
151 err=file->f_op->open(inode,file);
152 if (err) {
153 fops_put(file->f_op);
154 file->f_op = fops_get(old_fops);
155 }
156 }
157 fops_put(old_fops);
158fail:
Matthias Kaehlcke0e82d5b2007-05-08 00:32:08 -0700159 mutex_unlock(&misc_mtx);
Jonathan Corbet309c4552008-05-15 11:07:52 -0600160 unlock_kernel();
Linus Torvalds1da177e2005-04-16 15:20:36 -0700161 return err;
162}
163
gregkh@suse.deca8eca62005-03-23 09:53:09 -0800164static struct class *misc_class;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700165
Arjan van de Ven62322d22006-07-03 00:24:21 -0700166static const struct file_operations misc_fops = {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700167 .owner = THIS_MODULE,
168 .open = misc_open,
169};
170
171
172/**
173 * misc_register - register a miscellaneous device
174 * @misc: device structure
175 *
176 * Register a miscellaneous device with the kernel. If the minor
177 * number is set to %MISC_DYNAMIC_MINOR a minor number is assigned
178 * and placed in the minor field of the structure. For other cases
179 * the minor number requested is used.
180 *
181 * The structure passed is linked into the kernel and may not be
182 * destroyed until it has been unregistered.
183 *
184 * A zero is returned on success and a negative errno code for
185 * failure.
186 */
187
188int misc_register(struct miscdevice * misc)
189{
190 struct miscdevice *c;
191 dev_t dev;
Greg Kroah-Hartman7c69ef72005-06-20 21:15:16 -0700192 int err = 0;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700193
Neil Horman5d469ec2006-12-06 20:37:08 -0800194 INIT_LIST_HEAD(&misc->list);
195
Matthias Kaehlcke0e82d5b2007-05-08 00:32:08 -0700196 mutex_lock(&misc_mtx);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700197 list_for_each_entry(c, &misc_list, list) {
198 if (c->minor == misc->minor) {
Matthias Kaehlcke0e82d5b2007-05-08 00:32:08 -0700199 mutex_unlock(&misc_mtx);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700200 return -EBUSY;
201 }
202 }
203
204 if (misc->minor == MISC_DYNAMIC_MINOR) {
205 int i = DYNAMIC_MINORS;
206 while (--i >= 0)
207 if ( (misc_minors[i>>3] & (1 << (i&7))) == 0)
208 break;
209 if (i<0) {
Matthias Kaehlcke0e82d5b2007-05-08 00:32:08 -0700210 mutex_unlock(&misc_mtx);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700211 return -EBUSY;
212 }
213 misc->minor = i;
214 }
215
216 if (misc->minor < DYNAMIC_MINORS)
217 misc_minors[misc->minor >> 3] |= 1 << (misc->minor & 7);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700218 dev = MKDEV(MISC_MAJOR, misc->minor);
219
Greg Kroah-Hartman03457cd2008-07-21 20:03:34 -0700220 misc->this_device = device_create(misc_class, misc->parent, dev, NULL,
221 "%s", misc->name);
Greg Kroah-Hartman94fbcde2006-07-27 16:16:04 -0700222 if (IS_ERR(misc->this_device)) {
223 err = PTR_ERR(misc->this_device);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700224 goto out;
225 }
226
Linus Torvalds1da177e2005-04-16 15:20:36 -0700227 /*
228 * Add it to the front, so that later devices can "override"
229 * earlier defaults
230 */
231 list_add(&misc->list, &misc_list);
232 out:
Matthias Kaehlcke0e82d5b2007-05-08 00:32:08 -0700233 mutex_unlock(&misc_mtx);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700234 return err;
235}
236
237/**
Rafael J. Wysockib844eba2008-03-23 20:28:24 +0100238 * misc_deregister - unregister a miscellaneous device
Linus Torvalds1da177e2005-04-16 15:20:36 -0700239 * @misc: device to unregister
240 *
241 * Unregister a miscellaneous device that was previously
242 * successfully registered with misc_register(). Success
243 * is indicated by a zero return, a negative errno code
244 * indicates an error.
245 */
246
Rafael J. Wysockib844eba2008-03-23 20:28:24 +0100247int misc_deregister(struct miscdevice *misc)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700248{
249 int i = misc->minor;
250
251 if (list_empty(&misc->list))
252 return -EINVAL;
253
Matthias Kaehlcke0e82d5b2007-05-08 00:32:08 -0700254 mutex_lock(&misc_mtx);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700255 list_del(&misc->list);
Rafael J. Wysockib844eba2008-03-23 20:28:24 +0100256 device_destroy(misc_class, MKDEV(MISC_MAJOR, misc->minor));
Linus Torvalds1da177e2005-04-16 15:20:36 -0700257 if (i < DYNAMIC_MINORS && i>0) {
258 misc_minors[i>>3] &= ~(1 << (misc->minor & 7));
259 }
Matthias Kaehlcke0e82d5b2007-05-08 00:32:08 -0700260 mutex_unlock(&misc_mtx);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700261 return 0;
262}
263
264EXPORT_SYMBOL(misc_register);
Rafael J. Wysockib844eba2008-03-23 20:28:24 +0100265EXPORT_SYMBOL(misc_deregister);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700266
267static int __init misc_init(void)
268{
Denis V. Lunev1b502212008-04-29 01:02:34 -0700269 int err;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700270
Denis V. Lunev1b502212008-04-29 01:02:34 -0700271#ifdef CONFIG_PROC_FS
272 proc_create("misc", 0, NULL, &misc_proc_fops);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700273#endif
gregkh@suse.deca8eca62005-03-23 09:53:09 -0800274 misc_class = class_create(THIS_MODULE, "misc");
Denis V. Lunev1b502212008-04-29 01:02:34 -0700275 err = PTR_ERR(misc_class);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700276 if (IS_ERR(misc_class))
Denis V. Lunev1b502212008-04-29 01:02:34 -0700277 goto fail_remove;
Christoph Hellwig573fc112005-09-06 15:16:58 -0700278
Denis V. Lunev1b502212008-04-29 01:02:34 -0700279 err = -EIO;
280 if (register_chrdev(MISC_MAJOR,"misc",&misc_fops))
281 goto fail_printk;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700282 return 0;
Denis V. Lunev1b502212008-04-29 01:02:34 -0700283
284fail_printk:
285 printk("unable to get major %d for misc devices\n", MISC_MAJOR);
286 class_destroy(misc_class);
287fail_remove:
288 remove_proc_entry("misc", NULL);
289 return err;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700290}
291subsys_initcall(misc_init);