blob: 3e4c0414a01a2177d3a1d40638a5dc6b34aa5437 [file] [log] [blame]
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>
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 */
57static LIST_HEAD(misc_list);
58static DECLARE_MUTEX(misc_sem);
59
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{
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
82static 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
92static void misc_seq_stop(struct seq_file *seq, void *v)
93{
94 up(&misc_sem);
95}
96
97static 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
106static 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
113static int misc_seq_open(struct inode *inode, struct file *file)
114{
115 return seq_open(file, &misc_seq_ops);
116}
117
118static 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
127static 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);
169fail:
170 up(&misc_sem);
171 return err;
172}
173
174/*
175 * TODO for 2.7:
gregkh@suse.deca8eca62005-03-23 09:53:09 -0800176 * - add a struct kref to struct miscdevice and make all usages of
Linus Torvalds1da177e2005-04-16 15:20:36 -0700177 * them dynamic.
178 */
gregkh@suse.deca8eca62005-03-23 09:53:09 -0800179static struct class *misc_class;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700180
181static 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
203int 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
Greg Kroah-Hartman53f46542005-10-27 22:25:43 -0700237 misc->class = class_device_create(misc_class, NULL, dev, misc->dev,
gregkh@suse.deca8eca62005-03-23 09:53:09 -0800238 "%s", misc->name);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700239 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) {
gregkh@suse.deca8eca62005-03-23 09:53:09 -0800247 class_device_destroy(misc_class, dev);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700248 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
271int 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);
gregkh@suse.deca8eca62005-03-23 09:53:09 -0800280 class_device_destroy(misc_class, MKDEV(MISC_MAJOR, misc->minor));
Linus Torvalds1da177e2005-04-16 15:20:36 -0700281 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
289EXPORT_SYMBOL(misc_register);
290EXPORT_SYMBOL(misc_deregister);
291
292static 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
gregkh@suse.deca8eca62005-03-23 09:53:09 -0800301 misc_class = class_create(THIS_MODULE, "misc");
Linus Torvalds1da177e2005-04-16 15:20:36 -0700302 if (IS_ERR(misc_class))
303 return PTR_ERR(misc_class);
Christoph Hellwig573fc112005-09-06 15:16:58 -0700304
Linus Torvalds1da177e2005-04-16 15:20:36 -0700305 if (register_chrdev(MISC_MAJOR,"misc",&misc_fops)) {
306 printk("unable to get major %d for misc devices\n",
307 MISC_MAJOR);
gregkh@suse.deca8eca62005-03-23 09:53:09 -0800308 class_destroy(misc_class);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700309 return -EIO;
310 }
311 return 0;
312}
313subsys_initcall(misc_init);