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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>
Matthias Kaehlcke0e82d5b2007-05-08 00:32:08 -070043#include <linux/mutex.h>
Linus Torvalds1da177e2005-04-16 15:20:36 -070044#include <linux/proc_fs.h>
45#include <linux/seq_file.h>
Linus Torvalds1da177e2005-04-16 15:20:36 -070046#include <linux/stat.h>
47#include <linux/init.h>
48#include <linux/device.h>
49#include <linux/tty.h>
50#include <linux/kmod.h>
Tejun Heo5a0e3ad2010-03-24 17:04:11 +090051#include <linux/gfp.h>
Linus Torvalds1da177e2005-04-16 15:20:36 -070052
53/*
54 * Head entry for the doubly linked miscdevice list
55 */
56static LIST_HEAD(misc_list);
Matthias Kaehlcke0e82d5b2007-05-08 00:32:08 -070057static DEFINE_MUTEX(misc_mtx);
Linus Torvalds1da177e2005-04-16 15:20:36 -070058
59/*
60 * Assigned numbers, used for dynamic minors
61 */
62#define DYNAMIC_MINORS 64 /* like dynamic majors */
Thadeu Lima de Souza Cascardo1f2f38d2009-12-14 18:00:31 -080063static DECLARE_BITMAP(misc_minors, DYNAMIC_MINORS);
Linus Torvalds1da177e2005-04-16 15:20:36 -070064
Linus Torvalds1da177e2005-04-16 15:20:36 -070065#ifdef CONFIG_PROC_FS
66static void *misc_seq_start(struct seq_file *seq, loff_t *pos)
67{
Matthias Kaehlcke0e82d5b2007-05-08 00:32:08 -070068 mutex_lock(&misc_mtx);
Pavel Emelianov46c65b72007-07-15 23:39:53 -070069 return seq_list_start(&misc_list, *pos);
Linus Torvalds1da177e2005-04-16 15:20:36 -070070}
71
72static void *misc_seq_next(struct seq_file *seq, void *v, loff_t *pos)
73{
Pavel Emelianov46c65b72007-07-15 23:39:53 -070074 return seq_list_next(v, &misc_list, pos);
Linus Torvalds1da177e2005-04-16 15:20:36 -070075}
76
77static void misc_seq_stop(struct seq_file *seq, void *v)
78{
Matthias Kaehlcke0e82d5b2007-05-08 00:32:08 -070079 mutex_unlock(&misc_mtx);
Linus Torvalds1da177e2005-04-16 15:20:36 -070080}
81
82static int misc_seq_show(struct seq_file *seq, void *v)
83{
Pavel Emelianov46c65b72007-07-15 23:39:53 -070084 const struct miscdevice *p = list_entry(v, struct miscdevice, list);
Linus Torvalds1da177e2005-04-16 15:20:36 -070085
86 seq_printf(seq, "%3i %s\n", p->minor, p->name ? p->name : "");
87 return 0;
88}
89
90
James Morris88e9d342009-09-22 16:43:43 -070091static const struct seq_operations misc_seq_ops = {
Linus Torvalds1da177e2005-04-16 15:20:36 -070092 .start = misc_seq_start,
93 .next = misc_seq_next,
94 .stop = misc_seq_stop,
95 .show = misc_seq_show,
96};
97
98static int misc_seq_open(struct inode *inode, struct file *file)
99{
100 return seq_open(file, &misc_seq_ops);
101}
102
Arjan van de Ven62322d22006-07-03 00:24:21 -0700103static const struct file_operations misc_proc_fops = {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700104 .owner = THIS_MODULE,
105 .open = misc_seq_open,
106 .read = seq_read,
107 .llseek = seq_lseek,
108 .release = seq_release,
109};
110#endif
111
112static int misc_open(struct inode * inode, struct file * file)
113{
114 int minor = iminor(inode);
115 struct miscdevice *c;
116 int err = -ENODEV;
Arjan van de Ven99ac48f2006-03-28 01:56:41 -0800117 const struct file_operations *old_fops, *new_fops = NULL;
Thomas Gleixner40b798e2009-10-10 15:35:43 +0000118
Matthias Kaehlcke0e82d5b2007-05-08 00:32:08 -0700119 mutex_lock(&misc_mtx);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700120
121 list_for_each_entry(c, &misc_list, list) {
122 if (c->minor == minor) {
123 new_fops = fops_get(c->fops);
124 break;
125 }
126 }
127
128 if (!new_fops) {
Matthias Kaehlcke0e82d5b2007-05-08 00:32:08 -0700129 mutex_unlock(&misc_mtx);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700130 request_module("char-major-%d-%d", MISC_MAJOR, minor);
Matthias Kaehlcke0e82d5b2007-05-08 00:32:08 -0700131 mutex_lock(&misc_mtx);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700132
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
143 err = 0;
144 old_fops = file->f_op;
145 file->f_op = new_fops;
146 if (file->f_op->open) {
147 err=file->f_op->open(inode,file);
148 if (err) {
149 fops_put(file->f_op);
150 file->f_op = fops_get(old_fops);
151 }
152 }
153 fops_put(old_fops);
154fail:
Matthias Kaehlcke0e82d5b2007-05-08 00:32:08 -0700155 mutex_unlock(&misc_mtx);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700156 return err;
157}
158
gregkh@suse.deca8eca62005-03-23 09:53:09 -0800159static struct class *misc_class;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700160
Arjan van de Ven62322d22006-07-03 00:24:21 -0700161static const struct file_operations misc_fops = {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700162 .owner = THIS_MODULE,
163 .open = misc_open,
164};
165
Linus Torvalds1da177e2005-04-16 15:20:36 -0700166/**
167 * misc_register - register a miscellaneous device
168 * @misc: device structure
169 *
170 * Register a miscellaneous device with the kernel. If the minor
171 * number is set to %MISC_DYNAMIC_MINOR a minor number is assigned
172 * and placed in the minor field of the structure. For other cases
173 * the minor number requested is used.
174 *
175 * The structure passed is linked into the kernel and may not be
176 * destroyed until it has been unregistered.
177 *
178 * A zero is returned on success and a negative errno code for
179 * failure.
180 */
181
182int misc_register(struct miscdevice * misc)
183{
184 struct miscdevice *c;
185 dev_t dev;
Greg Kroah-Hartman7c69ef72005-06-20 21:15:16 -0700186 int err = 0;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700187
Neil Horman5d469ec2006-12-06 20:37:08 -0800188 INIT_LIST_HEAD(&misc->list);
189
Matthias Kaehlcke0e82d5b2007-05-08 00:32:08 -0700190 mutex_lock(&misc_mtx);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700191 list_for_each_entry(c, &misc_list, list) {
192 if (c->minor == misc->minor) {
Matthias Kaehlcke0e82d5b2007-05-08 00:32:08 -0700193 mutex_unlock(&misc_mtx);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700194 return -EBUSY;
195 }
196 }
197
198 if (misc->minor == MISC_DYNAMIC_MINOR) {
Thadeu Lima de Souza Cascardo1f2f38d2009-12-14 18:00:31 -0800199 int i = find_first_zero_bit(misc_minors, DYNAMIC_MINORS);
200 if (i >= DYNAMIC_MINORS) {
Matthias Kaehlcke0e82d5b2007-05-08 00:32:08 -0700201 mutex_unlock(&misc_mtx);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700202 return -EBUSY;
203 }
Thadeu Lima de Souza Cascardo1f2f38d2009-12-14 18:00:31 -0800204 misc->minor = DYNAMIC_MINORS - i - 1;
205 set_bit(i, misc_minors);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700206 }
207
Linus Torvalds1da177e2005-04-16 15:20:36 -0700208 dev = MKDEV(MISC_MAJOR, misc->minor);
209
Kay Sieversd4056402009-04-30 15:23:42 +0200210 misc->this_device = device_create(misc_class, misc->parent, dev,
211 misc, "%s", misc->name);
Greg Kroah-Hartman94fbcde2006-07-27 16:16:04 -0700212 if (IS_ERR(misc->this_device)) {
Thadeu Lima de Souza Cascardo1f2f38d2009-12-14 18:00:31 -0800213 int i = DYNAMIC_MINORS - misc->minor - 1;
Thadeu Lima de Souza Cascardo4ae717d2009-12-14 18:00:30 -0800214 if (i < DYNAMIC_MINORS && i >= 0)
Thadeu Lima de Souza Cascardo1f2f38d2009-12-14 18:00:31 -0800215 clear_bit(i, misc_minors);
Greg Kroah-Hartman94fbcde2006-07-27 16:16:04 -0700216 err = PTR_ERR(misc->this_device);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700217 goto out;
218 }
219
Linus Torvalds1da177e2005-04-16 15:20:36 -0700220 /*
221 * Add it to the front, so that later devices can "override"
222 * earlier defaults
223 */
224 list_add(&misc->list, &misc_list);
225 out:
Matthias Kaehlcke0e82d5b2007-05-08 00:32:08 -0700226 mutex_unlock(&misc_mtx);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700227 return err;
228}
229
230/**
Rafael J. Wysockib844eba2008-03-23 20:28:24 +0100231 * misc_deregister - unregister a miscellaneous device
Linus Torvalds1da177e2005-04-16 15:20:36 -0700232 * @misc: device to unregister
233 *
234 * Unregister a miscellaneous device that was previously
235 * successfully registered with misc_register(). Success
236 * is indicated by a zero return, a negative errno code
237 * indicates an error.
238 */
239
Rafael J. Wysockib844eba2008-03-23 20:28:24 +0100240int misc_deregister(struct miscdevice *misc)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700241{
Thadeu Lima de Souza Cascardo1f2f38d2009-12-14 18:00:31 -0800242 int i = DYNAMIC_MINORS - misc->minor - 1;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700243
244 if (list_empty(&misc->list))
245 return -EINVAL;
246
Matthias Kaehlcke0e82d5b2007-05-08 00:32:08 -0700247 mutex_lock(&misc_mtx);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700248 list_del(&misc->list);
Rafael J. Wysockib844eba2008-03-23 20:28:24 +0100249 device_destroy(misc_class, MKDEV(MISC_MAJOR, misc->minor));
Thadeu Lima de Souza Cascardo4ae717d2009-12-14 18:00:30 -0800250 if (i < DYNAMIC_MINORS && i >= 0)
Thadeu Lima de Souza Cascardo1f2f38d2009-12-14 18:00:31 -0800251 clear_bit(i, misc_minors);
Matthias Kaehlcke0e82d5b2007-05-08 00:32:08 -0700252 mutex_unlock(&misc_mtx);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700253 return 0;
254}
255
256EXPORT_SYMBOL(misc_register);
Rafael J. Wysockib844eba2008-03-23 20:28:24 +0100257EXPORT_SYMBOL(misc_deregister);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700258
Kay Sieverse454cea2009-09-18 23:01:12 +0200259static char *misc_devnode(struct device *dev, mode_t *mode)
Kay Sieversd4056402009-04-30 15:23:42 +0200260{
261 struct miscdevice *c = dev_get_drvdata(dev);
262
Kay Sieverse454cea2009-09-18 23:01:12 +0200263 if (mode && c->mode)
264 *mode = c->mode;
265 if (c->nodename)
266 return kstrdup(c->nodename, GFP_KERNEL);
Kay Sieversd4056402009-04-30 15:23:42 +0200267 return NULL;
268}
269
Linus Torvalds1da177e2005-04-16 15:20:36 -0700270static int __init misc_init(void)
271{
Denis V. Lunev1b502212008-04-29 01:02:34 -0700272 int err;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700273
Denis V. Lunev1b502212008-04-29 01:02:34 -0700274#ifdef CONFIG_PROC_FS
275 proc_create("misc", 0, NULL, &misc_proc_fops);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700276#endif
gregkh@suse.deca8eca62005-03-23 09:53:09 -0800277 misc_class = class_create(THIS_MODULE, "misc");
Denis V. Lunev1b502212008-04-29 01:02:34 -0700278 err = PTR_ERR(misc_class);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700279 if (IS_ERR(misc_class))
Denis V. Lunev1b502212008-04-29 01:02:34 -0700280 goto fail_remove;
Christoph Hellwig573fc112005-09-06 15:16:58 -0700281
Denis V. Lunev1b502212008-04-29 01:02:34 -0700282 err = -EIO;
283 if (register_chrdev(MISC_MAJOR,"misc",&misc_fops))
284 goto fail_printk;
Kay Sieverse454cea2009-09-18 23:01:12 +0200285 misc_class->devnode = misc_devnode;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700286 return 0;
Denis V. Lunev1b502212008-04-29 01:02:34 -0700287
288fail_printk:
289 printk("unable to get major %d for misc devices\n", MISC_MAJOR);
290 class_destroy(misc_class);
291fail_remove:
292 remove_proc_entry("misc", NULL);
293 return err;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700294}
295subsys_initcall(misc_init);