Commit | Line | Data |
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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> | |
44 | #include <linux/proc_fs.h> | |
45 | #include <linux/seq_file.h> | |
1da177e4 LT |
46 | #include <linux/stat.h> |
47 | #include <linux/init.h> | |
48 | #include <linux/device.h> | |
49 | #include <linux/tty.h> | |
50 | #include <linux/kmod.h> | |
51 | ||
52 | /* | |
53 | * Head entry for the doubly linked miscdevice list | |
54 | */ | |
55 | static LIST_HEAD(misc_list); | |
56 | static DECLARE_MUTEX(misc_sem); | |
57 | ||
58 | /* | |
59 | * Assigned numbers, used for dynamic minors | |
60 | */ | |
61 | #define DYNAMIC_MINORS 64 /* like dynamic majors */ | |
62 | static unsigned char misc_minors[DYNAMIC_MINORS / 8]; | |
63 | ||
1da177e4 | 64 | extern int pmu_device_init(void); |
1da177e4 LT |
65 | |
66 | #ifdef CONFIG_PROC_FS | |
67 | static void *misc_seq_start(struct seq_file *seq, loff_t *pos) | |
68 | { | |
69 | struct miscdevice *p; | |
70 | loff_t off = 0; | |
71 | ||
72 | down(&misc_sem); | |
73 | list_for_each_entry(p, &misc_list, list) { | |
74 | if (*pos == off++) | |
75 | return p; | |
76 | } | |
77 | return NULL; | |
78 | } | |
79 | ||
80 | static void *misc_seq_next(struct seq_file *seq, void *v, loff_t *pos) | |
81 | { | |
82 | struct list_head *n = ((struct miscdevice *)v)->list.next; | |
83 | ||
84 | ++*pos; | |
85 | ||
86 | return (n != &misc_list) ? list_entry(n, struct miscdevice, list) | |
87 | : NULL; | |
88 | } | |
89 | ||
90 | static void misc_seq_stop(struct seq_file *seq, void *v) | |
91 | { | |
92 | up(&misc_sem); | |
93 | } | |
94 | ||
95 | static int misc_seq_show(struct seq_file *seq, void *v) | |
96 | { | |
97 | const struct miscdevice *p = v; | |
98 | ||
99 | seq_printf(seq, "%3i %s\n", p->minor, p->name ? p->name : ""); | |
100 | return 0; | |
101 | } | |
102 | ||
103 | ||
104 | static struct seq_operations misc_seq_ops = { | |
105 | .start = misc_seq_start, | |
106 | .next = misc_seq_next, | |
107 | .stop = misc_seq_stop, | |
108 | .show = misc_seq_show, | |
109 | }; | |
110 | ||
111 | static int misc_seq_open(struct inode *inode, struct file *file) | |
112 | { | |
113 | return seq_open(file, &misc_seq_ops); | |
114 | } | |
115 | ||
62322d25 | 116 | static const struct file_operations misc_proc_fops = { |
1da177e4 LT |
117 | .owner = THIS_MODULE, |
118 | .open = misc_seq_open, | |
119 | .read = seq_read, | |
120 | .llseek = seq_lseek, | |
121 | .release = seq_release, | |
122 | }; | |
123 | #endif | |
124 | ||
125 | static int misc_open(struct inode * inode, struct file * file) | |
126 | { | |
127 | int minor = iminor(inode); | |
128 | struct miscdevice *c; | |
129 | int err = -ENODEV; | |
99ac48f5 | 130 | const struct file_operations *old_fops, *new_fops = NULL; |
1da177e4 LT |
131 | |
132 | down(&misc_sem); | |
133 | ||
134 | list_for_each_entry(c, &misc_list, list) { | |
135 | if (c->minor == minor) { | |
136 | new_fops = fops_get(c->fops); | |
137 | break; | |
138 | } | |
139 | } | |
140 | ||
141 | if (!new_fops) { | |
142 | up(&misc_sem); | |
143 | request_module("char-major-%d-%d", MISC_MAJOR, minor); | |
144 | down(&misc_sem); | |
145 | ||
146 | list_for_each_entry(c, &misc_list, list) { | |
147 | if (c->minor == minor) { | |
148 | new_fops = fops_get(c->fops); | |
149 | break; | |
150 | } | |
151 | } | |
152 | if (!new_fops) | |
153 | goto fail; | |
154 | } | |
155 | ||
156 | err = 0; | |
157 | old_fops = file->f_op; | |
158 | file->f_op = new_fops; | |
159 | if (file->f_op->open) { | |
160 | err=file->f_op->open(inode,file); | |
161 | if (err) { | |
162 | fops_put(file->f_op); | |
163 | file->f_op = fops_get(old_fops); | |
164 | } | |
165 | } | |
166 | fops_put(old_fops); | |
167 | fail: | |
168 | up(&misc_sem); | |
169 | return err; | |
170 | } | |
171 | ||
172 | /* | |
173 | * TODO for 2.7: | |
ca8eca68 | 174 | * - add a struct kref to struct miscdevice and make all usages of |
1da177e4 LT |
175 | * them dynamic. |
176 | */ | |
ca8eca68 | 177 | static struct class *misc_class; |
1da177e4 | 178 | |
62322d25 | 179 | static const struct file_operations misc_fops = { |
1da177e4 LT |
180 | .owner = THIS_MODULE, |
181 | .open = misc_open, | |
182 | }; | |
183 | ||
184 | ||
185 | /** | |
186 | * misc_register - register a miscellaneous device | |
187 | * @misc: device structure | |
188 | * | |
189 | * Register a miscellaneous device with the kernel. If the minor | |
190 | * number is set to %MISC_DYNAMIC_MINOR a minor number is assigned | |
191 | * and placed in the minor field of the structure. For other cases | |
192 | * the minor number requested is used. | |
193 | * | |
194 | * The structure passed is linked into the kernel and may not be | |
195 | * destroyed until it has been unregistered. | |
196 | * | |
197 | * A zero is returned on success and a negative errno code for | |
198 | * failure. | |
199 | */ | |
200 | ||
201 | int misc_register(struct miscdevice * misc) | |
202 | { | |
203 | struct miscdevice *c; | |
204 | dev_t dev; | |
7c69ef79 | 205 | int err = 0; |
1da177e4 LT |
206 | |
207 | down(&misc_sem); | |
208 | list_for_each_entry(c, &misc_list, list) { | |
209 | if (c->minor == misc->minor) { | |
210 | up(&misc_sem); | |
211 | return -EBUSY; | |
212 | } | |
213 | } | |
214 | ||
215 | if (misc->minor == MISC_DYNAMIC_MINOR) { | |
216 | int i = DYNAMIC_MINORS; | |
217 | while (--i >= 0) | |
218 | if ( (misc_minors[i>>3] & (1 << (i&7))) == 0) | |
219 | break; | |
220 | if (i<0) { | |
221 | up(&misc_sem); | |
222 | return -EBUSY; | |
223 | } | |
224 | misc->minor = i; | |
225 | } | |
226 | ||
227 | if (misc->minor < DYNAMIC_MINORS) | |
228 | misc_minors[misc->minor >> 3] |= 1 << (misc->minor & 7); | |
1da177e4 LT |
229 | dev = MKDEV(MISC_MAJOR, misc->minor); |
230 | ||
53f46542 | 231 | misc->class = class_device_create(misc_class, NULL, dev, misc->dev, |
ca8eca68 | 232 | "%s", misc->name); |
1da177e4 LT |
233 | if (IS_ERR(misc->class)) { |
234 | err = PTR_ERR(misc->class); | |
235 | goto out; | |
236 | } | |
237 | ||
1da177e4 LT |
238 | /* |
239 | * Add it to the front, so that later devices can "override" | |
240 | * earlier defaults | |
241 | */ | |
242 | list_add(&misc->list, &misc_list); | |
243 | out: | |
244 | up(&misc_sem); | |
245 | return err; | |
246 | } | |
247 | ||
248 | /** | |
249 | * misc_deregister - unregister a miscellaneous device | |
250 | * @misc: device to unregister | |
251 | * | |
252 | * Unregister a miscellaneous device that was previously | |
253 | * successfully registered with misc_register(). Success | |
254 | * is indicated by a zero return, a negative errno code | |
255 | * indicates an error. | |
256 | */ | |
257 | ||
258 | int misc_deregister(struct miscdevice * misc) | |
259 | { | |
260 | int i = misc->minor; | |
261 | ||
262 | if (list_empty(&misc->list)) | |
263 | return -EINVAL; | |
264 | ||
265 | down(&misc_sem); | |
266 | list_del(&misc->list); | |
ca8eca68 | 267 | class_device_destroy(misc_class, MKDEV(MISC_MAJOR, misc->minor)); |
1da177e4 LT |
268 | if (i < DYNAMIC_MINORS && i>0) { |
269 | misc_minors[i>>3] &= ~(1 << (misc->minor & 7)); | |
270 | } | |
271 | up(&misc_sem); | |
272 | return 0; | |
273 | } | |
274 | ||
275 | EXPORT_SYMBOL(misc_register); | |
276 | EXPORT_SYMBOL(misc_deregister); | |
277 | ||
278 | static int __init misc_init(void) | |
279 | { | |
280 | #ifdef CONFIG_PROC_FS | |
281 | struct proc_dir_entry *ent; | |
282 | ||
283 | ent = create_proc_entry("misc", 0, NULL); | |
284 | if (ent) | |
285 | ent->proc_fops = &misc_proc_fops; | |
286 | #endif | |
ca8eca68 | 287 | misc_class = class_create(THIS_MODULE, "misc"); |
1da177e4 LT |
288 | if (IS_ERR(misc_class)) |
289 | return PTR_ERR(misc_class); | |
573fc113 | 290 | |
1da177e4 LT |
291 | if (register_chrdev(MISC_MAJOR,"misc",&misc_fops)) { |
292 | printk("unable to get major %d for misc devices\n", | |
293 | MISC_MAJOR); | |
ca8eca68 | 294 | class_destroy(misc_class); |
1da177e4 LT |
295 | return -EIO; |
296 | } | |
297 | return 0; | |
298 | } | |
299 | subsys_initcall(misc_init); |