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> | |
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. |
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 | ||
53f46542 | 237 | misc->class = class_device_create(misc_class, NULL, 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)) |
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); |