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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> | |
0e82d5b6 | 44 | #include <linux/mutex.h> |
1da177e4 LT |
45 | #include <linux/proc_fs.h> |
46 | #include <linux/seq_file.h> | |
1da177e4 LT |
47 | #include <linux/stat.h> |
48 | #include <linux/init.h> | |
49 | #include <linux/device.h> | |
50 | #include <linux/tty.h> | |
51 | #include <linux/kmod.h> | |
309c4551 | 52 | #include <linux/smp_lock.h> |
1da177e4 LT |
53 | |
54 | /* | |
55 | * Head entry for the doubly linked miscdevice list | |
56 | */ | |
57 | static LIST_HEAD(misc_list); | |
0e82d5b6 | 58 | static DEFINE_MUTEX(misc_mtx); |
1da177e4 LT |
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 | { | |
0e82d5b6 | 71 | mutex_lock(&misc_mtx); |
46c65b71 | 72 | return seq_list_start(&misc_list, *pos); |
1da177e4 LT |
73 | } |
74 | ||
75 | static void *misc_seq_next(struct seq_file *seq, void *v, loff_t *pos) | |
76 | { | |
46c65b71 | 77 | return seq_list_next(v, &misc_list, pos); |
1da177e4 LT |
78 | } |
79 | ||
80 | static void misc_seq_stop(struct seq_file *seq, void *v) | |
81 | { | |
0e82d5b6 | 82 | mutex_unlock(&misc_mtx); |
1da177e4 LT |
83 | } |
84 | ||
85 | static int misc_seq_show(struct seq_file *seq, void *v) | |
86 | { | |
46c65b71 | 87 | const struct miscdevice *p = list_entry(v, struct miscdevice, list); |
1da177e4 LT |
88 | |
89 | seq_printf(seq, "%3i %s\n", p->minor, p->name ? p->name : ""); | |
90 | return 0; | |
91 | } | |
92 | ||
93 | ||
94 | static 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 | ||
101 | static int misc_seq_open(struct inode *inode, struct file *file) | |
102 | { | |
103 | return seq_open(file, &misc_seq_ops); | |
104 | } | |
105 | ||
62322d25 | 106 | static const struct file_operations misc_proc_fops = { |
1da177e4 LT |
107 | .owner = THIS_MODULE, |
108 | .open = misc_seq_open, | |
109 | .read = seq_read, | |
110 | .llseek = seq_lseek, | |
111 | .release = seq_release, | |
112 | }; | |
113 | #endif | |
114 | ||
115 | static int misc_open(struct inode * inode, struct file * file) | |
116 | { | |
117 | int minor = iminor(inode); | |
118 | struct miscdevice *c; | |
119 | int err = -ENODEV; | |
99ac48f5 | 120 | const struct file_operations *old_fops, *new_fops = NULL; |
1da177e4 | 121 | |
309c4551 | 122 | lock_kernel(); |
0e82d5b6 | 123 | mutex_lock(&misc_mtx); |
1da177e4 LT |
124 | |
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) { | |
0e82d5b6 | 133 | mutex_unlock(&misc_mtx); |
1da177e4 | 134 | request_module("char-major-%d-%d", MISC_MAJOR, minor); |
0e82d5b6 | 135 | mutex_lock(&misc_mtx); |
1da177e4 LT |
136 | |
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); | |
158 | fail: | |
0e82d5b6 | 159 | mutex_unlock(&misc_mtx); |
309c4551 | 160 | unlock_kernel(); |
1da177e4 LT |
161 | return err; |
162 | } | |
163 | ||
ca8eca68 | 164 | static struct class *misc_class; |
1da177e4 | 165 | |
62322d25 | 166 | static const struct file_operations misc_fops = { |
1da177e4 LT |
167 | .owner = THIS_MODULE, |
168 | .open = misc_open, | |
169 | }; | |
170 | ||
1da177e4 LT |
171 | /** |
172 | * misc_register - register a miscellaneous device | |
173 | * @misc: device structure | |
174 | * | |
175 | * Register a miscellaneous device with the kernel. If the minor | |
176 | * number is set to %MISC_DYNAMIC_MINOR a minor number is assigned | |
177 | * and placed in the minor field of the structure. For other cases | |
178 | * the minor number requested is used. | |
179 | * | |
180 | * The structure passed is linked into the kernel and may not be | |
181 | * destroyed until it has been unregistered. | |
182 | * | |
183 | * A zero is returned on success and a negative errno code for | |
184 | * failure. | |
185 | */ | |
186 | ||
187 | int misc_register(struct miscdevice * misc) | |
188 | { | |
189 | struct miscdevice *c; | |
190 | dev_t dev; | |
7c69ef79 | 191 | int err = 0; |
1da177e4 | 192 | |
5d469ec0 NH |
193 | INIT_LIST_HEAD(&misc->list); |
194 | ||
0e82d5b6 | 195 | mutex_lock(&misc_mtx); |
1da177e4 LT |
196 | list_for_each_entry(c, &misc_list, list) { |
197 | if (c->minor == misc->minor) { | |
0e82d5b6 | 198 | mutex_unlock(&misc_mtx); |
1da177e4 LT |
199 | return -EBUSY; |
200 | } | |
201 | } | |
202 | ||
203 | if (misc->minor == MISC_DYNAMIC_MINOR) { | |
204 | int i = DYNAMIC_MINORS; | |
205 | while (--i >= 0) | |
206 | if ( (misc_minors[i>>3] & (1 << (i&7))) == 0) | |
207 | break; | |
208 | if (i<0) { | |
0e82d5b6 | 209 | mutex_unlock(&misc_mtx); |
1da177e4 LT |
210 | return -EBUSY; |
211 | } | |
212 | misc->minor = i; | |
213 | } | |
214 | ||
215 | if (misc->minor < DYNAMIC_MINORS) | |
216 | misc_minors[misc->minor >> 3] |= 1 << (misc->minor & 7); | |
1da177e4 LT |
217 | dev = MKDEV(MISC_MAJOR, misc->minor); |
218 | ||
d4056405 KS |
219 | misc->this_device = device_create(misc_class, misc->parent, dev, |
220 | misc, "%s", misc->name); | |
94fbcded GKH |
221 | if (IS_ERR(misc->this_device)) { |
222 | err = PTR_ERR(misc->this_device); | |
1da177e4 LT |
223 | goto out; |
224 | } | |
225 | ||
1da177e4 LT |
226 | /* |
227 | * Add it to the front, so that later devices can "override" | |
228 | * earlier defaults | |
229 | */ | |
230 | list_add(&misc->list, &misc_list); | |
231 | out: | |
0e82d5b6 | 232 | mutex_unlock(&misc_mtx); |
1da177e4 LT |
233 | return err; |
234 | } | |
235 | ||
236 | /** | |
b844eba2 | 237 | * misc_deregister - unregister a miscellaneous device |
1da177e4 LT |
238 | * @misc: device to unregister |
239 | * | |
240 | * Unregister a miscellaneous device that was previously | |
241 | * successfully registered with misc_register(). Success | |
242 | * is indicated by a zero return, a negative errno code | |
243 | * indicates an error. | |
244 | */ | |
245 | ||
b844eba2 | 246 | int misc_deregister(struct miscdevice *misc) |
1da177e4 LT |
247 | { |
248 | int i = misc->minor; | |
249 | ||
250 | if (list_empty(&misc->list)) | |
251 | return -EINVAL; | |
252 | ||
0e82d5b6 | 253 | mutex_lock(&misc_mtx); |
1da177e4 | 254 | list_del(&misc->list); |
b844eba2 | 255 | device_destroy(misc_class, MKDEV(MISC_MAJOR, misc->minor)); |
1da177e4 LT |
256 | if (i < DYNAMIC_MINORS && i>0) { |
257 | misc_minors[i>>3] &= ~(1 << (misc->minor & 7)); | |
258 | } | |
0e82d5b6 | 259 | mutex_unlock(&misc_mtx); |
1da177e4 LT |
260 | return 0; |
261 | } | |
262 | ||
263 | EXPORT_SYMBOL(misc_register); | |
b844eba2 | 264 | EXPORT_SYMBOL(misc_deregister); |
1da177e4 | 265 | |
e454cea2 | 266 | static char *misc_devnode(struct device *dev, mode_t *mode) |
d4056405 KS |
267 | { |
268 | struct miscdevice *c = dev_get_drvdata(dev); | |
269 | ||
e454cea2 KS |
270 | if (mode && c->mode) |
271 | *mode = c->mode; | |
272 | if (c->nodename) | |
273 | return kstrdup(c->nodename, GFP_KERNEL); | |
d4056405 KS |
274 | return NULL; |
275 | } | |
276 | ||
1da177e4 LT |
277 | static int __init misc_init(void) |
278 | { | |
1b502217 | 279 | int err; |
1da177e4 | 280 | |
1b502217 DL |
281 | #ifdef CONFIG_PROC_FS |
282 | proc_create("misc", 0, NULL, &misc_proc_fops); | |
1da177e4 | 283 | #endif |
ca8eca68 | 284 | misc_class = class_create(THIS_MODULE, "misc"); |
1b502217 | 285 | err = PTR_ERR(misc_class); |
1da177e4 | 286 | if (IS_ERR(misc_class)) |
1b502217 | 287 | goto fail_remove; |
573fc113 | 288 | |
1b502217 DL |
289 | err = -EIO; |
290 | if (register_chrdev(MISC_MAJOR,"misc",&misc_fops)) | |
291 | goto fail_printk; | |
e454cea2 | 292 | misc_class->devnode = misc_devnode; |
1da177e4 | 293 | return 0; |
1b502217 DL |
294 | |
295 | fail_printk: | |
296 | printk("unable to get major %d for misc devices\n", MISC_MAJOR); | |
297 | class_destroy(misc_class); | |
298 | fail_remove: | |
299 | remove_proc_entry("misc", NULL); | |
300 | return err; | |
1da177e4 LT |
301 | } |
302 | subsys_initcall(misc_init); |