Commit | Line | Data |
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b2441318 | 1 | // SPDX-License-Identifier: GPL-2.0 |
1da177e4 LT |
2 | /* |
3 | * linux/fs/char_dev.c | |
4 | * | |
5 | * Copyright (C) 1991, 1992 Linus Torvalds | |
6 | */ | |
7 | ||
1da177e4 LT |
8 | #include <linux/init.h> |
9 | #include <linux/fs.h> | |
b446b60e | 10 | #include <linux/kdev_t.h> |
1da177e4 LT |
11 | #include <linux/slab.h> |
12 | #include <linux/string.h> | |
13 | ||
14 | #include <linux/major.h> | |
15 | #include <linux/errno.h> | |
16 | #include <linux/module.h> | |
68eef3b4 | 17 | #include <linux/seq_file.h> |
1da177e4 LT |
18 | |
19 | #include <linux/kobject.h> | |
20 | #include <linux/kobj_map.h> | |
21 | #include <linux/cdev.h> | |
58383af6 | 22 | #include <linux/mutex.h> |
5da6185b | 23 | #include <linux/backing-dev.h> |
31d1d48e | 24 | #include <linux/tty.h> |
1da177e4 | 25 | |
07f3f05c | 26 | #include "internal.h" |
1da177e4 | 27 | |
68279f9c | 28 | static struct kobj_map *cdev_map __ro_after_init; |
1da177e4 | 29 | |
58383af6 | 30 | static DEFINE_MUTEX(chrdevs_lock); |
1da177e4 | 31 | |
8a932f73 LG |
32 | #define CHRDEV_MAJOR_HASH_SIZE 255 |
33 | ||
1da177e4 LT |
34 | static struct char_device_struct { |
35 | struct char_device_struct *next; | |
36 | unsigned int major; | |
37 | unsigned int baseminor; | |
38 | int minorct; | |
7170be5f | 39 | char name[64]; |
1da177e4 | 40 | struct cdev *cdev; /* will die */ |
68eef3b4 | 41 | } *chrdevs[CHRDEV_MAJOR_HASH_SIZE]; |
1da177e4 LT |
42 | |
43 | /* index in the above */ | |
e61eb2e9 | 44 | static inline int major_to_index(unsigned major) |
1da177e4 | 45 | { |
68eef3b4 | 46 | return major % CHRDEV_MAJOR_HASH_SIZE; |
7170be5f NH |
47 | } |
48 | ||
68eef3b4 | 49 | #ifdef CONFIG_PROC_FS |
7170be5f | 50 | |
68eef3b4 | 51 | void chrdev_show(struct seq_file *f, off_t offset) |
7170be5f NH |
52 | { |
53 | struct char_device_struct *cd; | |
7170be5f | 54 | |
8a932f73 LG |
55 | mutex_lock(&chrdevs_lock); |
56 | for (cd = chrdevs[major_to_index(offset)]; cd; cd = cd->next) { | |
57 | if (cd->major == offset) | |
68eef3b4 | 58 | seq_printf(f, "%3d %s\n", cd->major, cd->name); |
1da177e4 | 59 | } |
8a932f73 | 60 | mutex_unlock(&chrdevs_lock); |
7170be5f NH |
61 | } |
62 | ||
68eef3b4 | 63 | #endif /* CONFIG_PROC_FS */ |
1da177e4 | 64 | |
a5d31a3f LG |
65 | static int find_dynamic_major(void) |
66 | { | |
67 | int i; | |
68 | struct char_device_struct *cd; | |
69 | ||
652d703b | 70 | for (i = ARRAY_SIZE(chrdevs)-1; i >= CHRDEV_MAJOR_DYN_END; i--) { |
a5d31a3f LG |
71 | if (chrdevs[i] == NULL) |
72 | return i; | |
73 | } | |
74 | ||
75 | for (i = CHRDEV_MAJOR_DYN_EXT_START; | |
652d703b | 76 | i >= CHRDEV_MAJOR_DYN_EXT_END; i--) { |
a5d31a3f LG |
77 | for (cd = chrdevs[major_to_index(i)]; cd; cd = cd->next) |
78 | if (cd->major == i) | |
79 | break; | |
80 | ||
652d703b | 81 | if (cd == NULL) |
a5d31a3f LG |
82 | return i; |
83 | } | |
84 | ||
85 | return -EBUSY; | |
86 | } | |
87 | ||
1da177e4 LT |
88 | /* |
89 | * Register a single major with a specified minor range. | |
90 | * | |
d358b173 CX |
91 | * If major == 0 this function will dynamically allocate an unused major. |
92 | * If major > 0 this function will attempt to reserve the range of minors | |
93 | * with given major. | |
1da177e4 | 94 | * |
1da177e4 LT |
95 | */ |
96 | static struct char_device_struct * | |
97 | __register_chrdev_region(unsigned int major, unsigned int baseminor, | |
98 | int minorct, const char *name) | |
99 | { | |
4b0be572 | 100 | struct char_device_struct *cd, *curr, *prev = NULL; |
7ef0b152 | 101 | int ret; |
1da177e4 LT |
102 | int i; |
103 | ||
4b0be572 CX |
104 | if (major >= CHRDEV_MAJOR_MAX) { |
105 | pr_err("CHRDEV \"%s\" major requested (%u) is greater than the maximum (%u)\n", | |
106 | name, major, CHRDEV_MAJOR_MAX-1); | |
107 | return ERR_PTR(-EINVAL); | |
108 | } | |
109 | ||
4712d379 CX |
110 | if (minorct > MINORMASK + 1 - baseminor) { |
111 | pr_err("CHRDEV \"%s\" minor range requested (%u-%u) is out of range of maximum range (%u-%u) for a single major\n", | |
112 | name, baseminor, baseminor + minorct - 1, 0, MINORMASK); | |
113 | return ERR_PTR(-EINVAL); | |
114 | } | |
115 | ||
11b0b5ab | 116 | cd = kzalloc(sizeof(struct char_device_struct), GFP_KERNEL); |
1da177e4 LT |
117 | if (cd == NULL) |
118 | return ERR_PTR(-ENOMEM); | |
119 | ||
58383af6 | 120 | mutex_lock(&chrdevs_lock); |
1da177e4 | 121 | |
1da177e4 | 122 | if (major == 0) { |
a5d31a3f LG |
123 | ret = find_dynamic_major(); |
124 | if (ret < 0) { | |
125 | pr_err("CHRDEV \"%s\" dynamic allocation region is full\n", | |
126 | name); | |
1da177e4 LT |
127 | goto out; |
128 | } | |
a5d31a3f | 129 | major = ret; |
1da177e4 LT |
130 | } |
131 | ||
7ef0b152 | 132 | ret = -EBUSY; |
1da177e4 | 133 | i = major_to_index(major); |
4b0be572 CX |
134 | for (curr = chrdevs[i]; curr; prev = curr, curr = curr->next) { |
135 | if (curr->major < major) | |
136 | continue; | |
1da177e4 | 137 | |
4b0be572 | 138 | if (curr->major > major) |
1da177e4 | 139 | break; |
01d553d0 | 140 | |
4b0be572 CX |
141 | if (curr->baseminor + curr->minorct <= baseminor) |
142 | continue; | |
01d553d0 | 143 | |
4b0be572 CX |
144 | if (curr->baseminor >= baseminor + minorct) |
145 | break; | |
01d553d0 | 146 | |
4b0be572 CX |
147 | goto out; |
148 | } | |
de36e16d | 149 | |
4b0be572 CX |
150 | cd->major = major; |
151 | cd->baseminor = baseminor; | |
152 | cd->minorct = minorct; | |
c642256b | 153 | strscpy(cd->name, name, sizeof(cd->name)); |
de36e16d | 154 | |
4b0be572 CX |
155 | if (!prev) { |
156 | cd->next = curr; | |
157 | chrdevs[i] = cd; | |
158 | } else { | |
159 | cd->next = prev->next; | |
160 | prev->next = cd; | |
1da177e4 | 161 | } |
01d553d0 | 162 | |
58383af6 | 163 | mutex_unlock(&chrdevs_lock); |
1da177e4 LT |
164 | return cd; |
165 | out: | |
58383af6 | 166 | mutex_unlock(&chrdevs_lock); |
1da177e4 LT |
167 | kfree(cd); |
168 | return ERR_PTR(ret); | |
169 | } | |
170 | ||
171 | static struct char_device_struct * | |
172 | __unregister_chrdev_region(unsigned major, unsigned baseminor, int minorct) | |
173 | { | |
174 | struct char_device_struct *cd = NULL, **cp; | |
175 | int i = major_to_index(major); | |
176 | ||
58383af6 | 177 | mutex_lock(&chrdevs_lock); |
1da177e4 LT |
178 | for (cp = &chrdevs[i]; *cp; cp = &(*cp)->next) |
179 | if ((*cp)->major == major && | |
180 | (*cp)->baseminor == baseminor && | |
181 | (*cp)->minorct == minorct) | |
182 | break; | |
183 | if (*cp) { | |
184 | cd = *cp; | |
185 | *cp = cd->next; | |
186 | } | |
58383af6 | 187 | mutex_unlock(&chrdevs_lock); |
1da177e4 LT |
188 | return cd; |
189 | } | |
190 | ||
cf3e43db JC |
191 | /** |
192 | * register_chrdev_region() - register a range of device numbers | |
193 | * @from: the first in the desired range of device numbers; must include | |
194 | * the major number. | |
195 | * @count: the number of consecutive device numbers required | |
196 | * @name: the name of the device or driver. | |
197 | * | |
198 | * Return value is zero on success, a negative error code on failure. | |
199 | */ | |
1da177e4 LT |
200 | int register_chrdev_region(dev_t from, unsigned count, const char *name) |
201 | { | |
202 | struct char_device_struct *cd; | |
203 | dev_t to = from + count; | |
204 | dev_t n, next; | |
205 | ||
206 | for (n = from; n < to; n = next) { | |
207 | next = MKDEV(MAJOR(n)+1, 0); | |
208 | if (next > to) | |
209 | next = to; | |
210 | cd = __register_chrdev_region(MAJOR(n), MINOR(n), | |
211 | next - n, name); | |
212 | if (IS_ERR(cd)) | |
213 | goto fail; | |
214 | } | |
215 | return 0; | |
216 | fail: | |
217 | to = n; | |
218 | for (n = from; n < to; n = next) { | |
219 | next = MKDEV(MAJOR(n)+1, 0); | |
220 | kfree(__unregister_chrdev_region(MAJOR(n), MINOR(n), next - n)); | |
221 | } | |
222 | return PTR_ERR(cd); | |
223 | } | |
224 | ||
cf3e43db JC |
225 | /** |
226 | * alloc_chrdev_region() - register a range of char device numbers | |
227 | * @dev: output parameter for first assigned number | |
228 | * @baseminor: first of the requested range of minor numbers | |
229 | * @count: the number of minor numbers required | |
230 | * @name: the name of the associated device or driver | |
231 | * | |
232 | * Allocates a range of char device numbers. The major number will be | |
233 | * chosen dynamically, and returned (along with the first minor number) | |
234 | * in @dev. Returns zero or a negative error code. | |
235 | */ | |
1da177e4 LT |
236 | int alloc_chrdev_region(dev_t *dev, unsigned baseminor, unsigned count, |
237 | const char *name) | |
238 | { | |
239 | struct char_device_struct *cd; | |
240 | cd = __register_chrdev_region(0, baseminor, count, name); | |
241 | if (IS_ERR(cd)) | |
242 | return PTR_ERR(cd); | |
243 | *dev = MKDEV(cd->major, cd->baseminor); | |
244 | return 0; | |
245 | } | |
246 | ||
d247e2c6 | 247 | /** |
1905b1bf | 248 | * __register_chrdev() - create and register a cdev occupying a range of minors |
d247e2c6 | 249 | * @major: major device number or 0 for dynamic allocation |
1905b1bf TH |
250 | * @baseminor: first of the requested range of minor numbers |
251 | * @count: the number of minor numbers required | |
d247e2c6 REB |
252 | * @name: name of this range of devices |
253 | * @fops: file operations associated with this devices | |
254 | * | |
255 | * If @major == 0 this functions will dynamically allocate a major and return | |
256 | * its number. | |
257 | * | |
258 | * If @major > 0 this function will attempt to reserve a device with the given | |
259 | * major number and will return zero on success. | |
260 | * | |
261 | * Returns a -ve errno on failure. | |
262 | * | |
263 | * The name of this device has nothing to do with the name of the device in | |
264 | * /dev. It only helps to keep track of the different owners of devices. If | |
265 | * your module name has only one type of devices it's ok to use e.g. the name | |
266 | * of the module here. | |
d247e2c6 | 267 | */ |
1905b1bf TH |
268 | int __register_chrdev(unsigned int major, unsigned int baseminor, |
269 | unsigned int count, const char *name, | |
270 | const struct file_operations *fops) | |
1da177e4 LT |
271 | { |
272 | struct char_device_struct *cd; | |
273 | struct cdev *cdev; | |
1da177e4 LT |
274 | int err = -ENOMEM; |
275 | ||
1905b1bf | 276 | cd = __register_chrdev_region(major, baseminor, count, name); |
1da177e4 LT |
277 | if (IS_ERR(cd)) |
278 | return PTR_ERR(cd); | |
1ff97647 | 279 | |
1da177e4 LT |
280 | cdev = cdev_alloc(); |
281 | if (!cdev) | |
282 | goto out2; | |
283 | ||
284 | cdev->owner = fops->owner; | |
285 | cdev->ops = fops; | |
286 | kobject_set_name(&cdev->kobj, "%s", name); | |
1ff97647 | 287 | |
1905b1bf | 288 | err = cdev_add(cdev, MKDEV(cd->major, baseminor), count); |
1da177e4 LT |
289 | if (err) |
290 | goto out; | |
291 | ||
292 | cd->cdev = cdev; | |
293 | ||
294 | return major ? 0 : cd->major; | |
295 | out: | |
296 | kobject_put(&cdev->kobj); | |
297 | out2: | |
1905b1bf | 298 | kfree(__unregister_chrdev_region(cd->major, baseminor, count)); |
1da177e4 LT |
299 | return err; |
300 | } | |
301 | ||
cf3e43db | 302 | /** |
594069bc | 303 | * unregister_chrdev_region() - unregister a range of device numbers |
cf3e43db JC |
304 | * @from: the first in the range of numbers to unregister |
305 | * @count: the number of device numbers to unregister | |
306 | * | |
307 | * This function will unregister a range of @count device numbers, | |
308 | * starting with @from. The caller should normally be the one who | |
309 | * allocated those numbers in the first place... | |
310 | */ | |
1da177e4 LT |
311 | void unregister_chrdev_region(dev_t from, unsigned count) |
312 | { | |
313 | dev_t to = from + count; | |
314 | dev_t n, next; | |
315 | ||
316 | for (n = from; n < to; n = next) { | |
317 | next = MKDEV(MAJOR(n)+1, 0); | |
318 | if (next > to) | |
319 | next = to; | |
320 | kfree(__unregister_chrdev_region(MAJOR(n), MINOR(n), next - n)); | |
321 | } | |
322 | } | |
323 | ||
1905b1bf TH |
324 | /** |
325 | * __unregister_chrdev - unregister and destroy a cdev | |
326 | * @major: major device number | |
327 | * @baseminor: first of the range of minor numbers | |
328 | * @count: the number of minor numbers this cdev is occupying | |
329 | * @name: name of this range of devices | |
330 | * | |
331 | * Unregister and destroy the cdev occupying the region described by | |
332 | * @major, @baseminor and @count. This function undoes what | |
333 | * __register_chrdev() did. | |
334 | */ | |
335 | void __unregister_chrdev(unsigned int major, unsigned int baseminor, | |
336 | unsigned int count, const char *name) | |
1da177e4 LT |
337 | { |
338 | struct char_device_struct *cd; | |
1905b1bf TH |
339 | |
340 | cd = __unregister_chrdev_region(major, baseminor, count); | |
1da177e4 LT |
341 | if (cd && cd->cdev) |
342 | cdev_del(cd->cdev); | |
343 | kfree(cd); | |
1da177e4 LT |
344 | } |
345 | ||
346 | static DEFINE_SPINLOCK(cdev_lock); | |
347 | ||
348 | static struct kobject *cdev_get(struct cdev *p) | |
349 | { | |
350 | struct module *owner = p->owner; | |
351 | struct kobject *kobj; | |
352 | ||
e311ba29 | 353 | if (!try_module_get(owner)) |
1da177e4 | 354 | return NULL; |
68faa679 | 355 | kobj = kobject_get_unless_zero(&p->kobj); |
1da177e4 LT |
356 | if (!kobj) |
357 | module_put(owner); | |
358 | return kobj; | |
359 | } | |
360 | ||
361 | void cdev_put(struct cdev *p) | |
362 | { | |
363 | if (p) { | |
7da6844c | 364 | struct module *owner = p->owner; |
1da177e4 | 365 | kobject_put(&p->kobj); |
7da6844c | 366 | module_put(owner); |
1da177e4 LT |
367 | } |
368 | } | |
369 | ||
370 | /* | |
371 | * Called every time a character special file is opened | |
372 | */ | |
922f9cfa | 373 | static int chrdev_open(struct inode *inode, struct file *filp) |
1da177e4 | 374 | { |
e84f9e57 | 375 | const struct file_operations *fops; |
1da177e4 LT |
376 | struct cdev *p; |
377 | struct cdev *new = NULL; | |
378 | int ret = 0; | |
379 | ||
380 | spin_lock(&cdev_lock); | |
381 | p = inode->i_cdev; | |
382 | if (!p) { | |
383 | struct kobject *kobj; | |
384 | int idx; | |
385 | spin_unlock(&cdev_lock); | |
386 | kobj = kobj_lookup(cdev_map, inode->i_rdev, &idx); | |
387 | if (!kobj) | |
388 | return -ENXIO; | |
389 | new = container_of(kobj, struct cdev, kobj); | |
390 | spin_lock(&cdev_lock); | |
a30427d9 JC |
391 | /* Check i_cdev again in case somebody beat us to it while |
392 | we dropped the lock. */ | |
1da177e4 LT |
393 | p = inode->i_cdev; |
394 | if (!p) { | |
395 | inode->i_cdev = p = new; | |
1da177e4 LT |
396 | list_add(&inode->i_devices, &p->list); |
397 | new = NULL; | |
398 | } else if (!cdev_get(p)) | |
399 | ret = -ENXIO; | |
400 | } else if (!cdev_get(p)) | |
401 | ret = -ENXIO; | |
402 | spin_unlock(&cdev_lock); | |
403 | cdev_put(new); | |
404 | if (ret) | |
405 | return ret; | |
a518ab93 CH |
406 | |
407 | ret = -ENXIO; | |
e84f9e57 AV |
408 | fops = fops_get(p->ops); |
409 | if (!fops) | |
a518ab93 CH |
410 | goto out_cdev_put; |
411 | ||
e84f9e57 | 412 | replace_fops(filp, fops); |
a518ab93 | 413 | if (filp->f_op->open) { |
1ff97647 | 414 | ret = filp->f_op->open(inode, filp); |
a518ab93 CH |
415 | if (ret) |
416 | goto out_cdev_put; | |
417 | } | |
418 | ||
419 | return 0; | |
420 | ||
421 | out_cdev_put: | |
422 | cdev_put(p); | |
1da177e4 LT |
423 | return ret; |
424 | } | |
425 | ||
426 | void cd_forget(struct inode *inode) | |
427 | { | |
428 | spin_lock(&cdev_lock); | |
429 | list_del_init(&inode->i_devices); | |
430 | inode->i_cdev = NULL; | |
3bc52c45 | 431 | inode->i_mapping = &inode->i_data; |
1da177e4 LT |
432 | spin_unlock(&cdev_lock); |
433 | } | |
434 | ||
75c96f85 | 435 | static void cdev_purge(struct cdev *cdev) |
1da177e4 LT |
436 | { |
437 | spin_lock(&cdev_lock); | |
438 | while (!list_empty(&cdev->list)) { | |
439 | struct inode *inode; | |
440 | inode = container_of(cdev->list.next, struct inode, i_devices); | |
441 | list_del_init(&inode->i_devices); | |
442 | inode->i_cdev = NULL; | |
443 | } | |
444 | spin_unlock(&cdev_lock); | |
445 | } | |
446 | ||
447 | /* | |
448 | * Dummy default file-operations: the only thing this does | |
449 | * is contain the open that then fills in the correct operations | |
450 | * depending on the special file... | |
451 | */ | |
4b6f5d20 | 452 | const struct file_operations def_chr_fops = { |
1da177e4 | 453 | .open = chrdev_open, |
6038f373 | 454 | .llseek = noop_llseek, |
1da177e4 LT |
455 | }; |
456 | ||
457 | static struct kobject *exact_match(dev_t dev, int *part, void *data) | |
458 | { | |
459 | struct cdev *p = data; | |
460 | return &p->kobj; | |
461 | } | |
462 | ||
463 | static int exact_lock(dev_t dev, void *data) | |
464 | { | |
465 | struct cdev *p = data; | |
466 | return cdev_get(p) ? 0 : -1; | |
467 | } | |
468 | ||
cf3e43db JC |
469 | /** |
470 | * cdev_add() - add a char device to the system | |
471 | * @p: the cdev structure for the device | |
472 | * @dev: the first device number for which this device is responsible | |
473 | * @count: the number of consecutive minor numbers corresponding to this | |
474 | * device | |
475 | * | |
476 | * cdev_add() adds the device represented by @p to the system, making it | |
477 | * live immediately. A negative error code is returned on failure. | |
478 | */ | |
1da177e4 LT |
479 | int cdev_add(struct cdev *p, dev_t dev, unsigned count) |
480 | { | |
2f0157f1 DT |
481 | int error; |
482 | ||
1da177e4 LT |
483 | p->dev = dev; |
484 | p->count = count; | |
2f0157f1 | 485 | |
4634c973 SX |
486 | if (WARN_ON(dev == WHITEOUT_DEV)) { |
487 | error = -EBUSY; | |
488 | goto err; | |
489 | } | |
a3c751a5 | 490 | |
2f0157f1 DT |
491 | error = kobj_map(cdev_map, dev, count, NULL, |
492 | exact_match, exact_lock, p); | |
493 | if (error) | |
4634c973 | 494 | goto err; |
2f0157f1 DT |
495 | |
496 | kobject_get(p->kobj.parent); | |
497 | ||
498 | return 0; | |
4634c973 SX |
499 | |
500 | err: | |
501 | kfree_const(p->kobj.name); | |
502 | p->kobj.name = NULL; | |
503 | return error; | |
1da177e4 LT |
504 | } |
505 | ||
233ed09d LG |
506 | /** |
507 | * cdev_set_parent() - set the parent kobject for a char device | |
508 | * @p: the cdev structure | |
509 | * @kobj: the kobject to take a reference to | |
510 | * | |
511 | * cdev_set_parent() sets a parent kobject which will be referenced | |
512 | * appropriately so the parent is not freed before the cdev. This | |
513 | * should be called before cdev_add. | |
514 | */ | |
515 | void cdev_set_parent(struct cdev *p, struct kobject *kobj) | |
516 | { | |
517 | WARN_ON(!kobj->state_initialized); | |
518 | p->kobj.parent = kobj; | |
519 | } | |
520 | ||
521 | /** | |
522 | * cdev_device_add() - add a char device and it's corresponding | |
523 | * struct device, linkink | |
524 | * @dev: the device structure | |
525 | * @cdev: the cdev structure | |
526 | * | |
527 | * cdev_device_add() adds the char device represented by @cdev to the system, | |
528 | * just as cdev_add does. It then adds @dev to the system using device_add | |
529 | * The dev_t for the char device will be taken from the struct device which | |
530 | * needs to be initialized first. This helper function correctly takes a | |
531 | * reference to the parent device so the parent will not get released until | |
532 | * all references to the cdev are released. | |
533 | * | |
534 | * This helper uses dev->devt for the device number. If it is not set | |
535 | * it will not add the cdev and it will be equivalent to device_add. | |
536 | * | |
537 | * This function should be used whenever the struct cdev and the | |
538 | * struct device are members of the same structure whose lifetime is | |
539 | * managed by the struct device. | |
540 | * | |
541 | * NOTE: Callers must assume that userspace was able to open the cdev and | |
542 | * can call cdev fops callbacks at any time, even if this function fails. | |
543 | */ | |
544 | int cdev_device_add(struct cdev *cdev, struct device *dev) | |
545 | { | |
546 | int rc = 0; | |
547 | ||
548 | if (dev->devt) { | |
549 | cdev_set_parent(cdev, &dev->kobj); | |
550 | ||
551 | rc = cdev_add(cdev, dev->devt, 1); | |
552 | if (rc) | |
553 | return rc; | |
554 | } | |
555 | ||
556 | rc = device_add(dev); | |
11fa7fef | 557 | if (rc && dev->devt) |
233ed09d LG |
558 | cdev_del(cdev); |
559 | ||
560 | return rc; | |
561 | } | |
562 | ||
563 | /** | |
564 | * cdev_device_del() - inverse of cdev_device_add | |
565 | * @dev: the device structure | |
566 | * @cdev: the cdev structure | |
567 | * | |
568 | * cdev_device_del() is a helper function to call cdev_del and device_del. | |
569 | * It should be used whenever cdev_device_add is used. | |
570 | * | |
571 | * If dev->devt is not set it will not remove the cdev and will be equivalent | |
572 | * to device_del. | |
573 | * | |
574 | * NOTE: This guarantees that associated sysfs callbacks are not running | |
575 | * or runnable, however any cdevs already open will remain and their fops | |
576 | * will still be callable even after this function returns. | |
577 | */ | |
578 | void cdev_device_del(struct cdev *cdev, struct device *dev) | |
579 | { | |
580 | device_del(dev); | |
581 | if (dev->devt) | |
582 | cdev_del(cdev); | |
583 | } | |
584 | ||
1da177e4 LT |
585 | static void cdev_unmap(dev_t dev, unsigned count) |
586 | { | |
587 | kobj_unmap(cdev_map, dev, count); | |
588 | } | |
589 | ||
cf3e43db JC |
590 | /** |
591 | * cdev_del() - remove a cdev from the system | |
592 | * @p: the cdev structure to be removed | |
593 | * | |
594 | * cdev_del() removes @p from the system, possibly freeing the structure | |
595 | * itself. | |
233ed09d LG |
596 | * |
597 | * NOTE: This guarantees that cdev device will no longer be able to be | |
598 | * opened, however any cdevs already open will remain and their fops will | |
599 | * still be callable even after cdev_del returns. | |
cf3e43db | 600 | */ |
1da177e4 LT |
601 | void cdev_del(struct cdev *p) |
602 | { | |
603 | cdev_unmap(p->dev, p->count); | |
604 | kobject_put(&p->kobj); | |
605 | } | |
606 | ||
607 | ||
608 | static void cdev_default_release(struct kobject *kobj) | |
609 | { | |
610 | struct cdev *p = container_of(kobj, struct cdev, kobj); | |
2f0157f1 DT |
611 | struct kobject *parent = kobj->parent; |
612 | ||
1da177e4 | 613 | cdev_purge(p); |
2f0157f1 | 614 | kobject_put(parent); |
1da177e4 LT |
615 | } |
616 | ||
617 | static void cdev_dynamic_release(struct kobject *kobj) | |
618 | { | |
619 | struct cdev *p = container_of(kobj, struct cdev, kobj); | |
2f0157f1 DT |
620 | struct kobject *parent = kobj->parent; |
621 | ||
1da177e4 LT |
622 | cdev_purge(p); |
623 | kfree(p); | |
2f0157f1 | 624 | kobject_put(parent); |
1da177e4 LT |
625 | } |
626 | ||
627 | static struct kobj_type ktype_cdev_default = { | |
628 | .release = cdev_default_release, | |
629 | }; | |
630 | ||
631 | static struct kobj_type ktype_cdev_dynamic = { | |
632 | .release = cdev_dynamic_release, | |
633 | }; | |
634 | ||
cf3e43db JC |
635 | /** |
636 | * cdev_alloc() - allocate a cdev structure | |
637 | * | |
638 | * Allocates and returns a cdev structure, or NULL on failure. | |
639 | */ | |
1da177e4 LT |
640 | struct cdev *cdev_alloc(void) |
641 | { | |
11b0b5ab | 642 | struct cdev *p = kzalloc(sizeof(struct cdev), GFP_KERNEL); |
1da177e4 | 643 | if (p) { |
1da177e4 | 644 | INIT_LIST_HEAD(&p->list); |
f9cb074b | 645 | kobject_init(&p->kobj, &ktype_cdev_dynamic); |
1da177e4 LT |
646 | } |
647 | return p; | |
648 | } | |
649 | ||
cf3e43db JC |
650 | /** |
651 | * cdev_init() - initialize a cdev structure | |
652 | * @cdev: the structure to initialize | |
653 | * @fops: the file_operations for this device | |
654 | * | |
655 | * Initializes @cdev, remembering @fops, making it ready to add to the | |
656 | * system with cdev_add(). | |
657 | */ | |
99ac48f5 | 658 | void cdev_init(struct cdev *cdev, const struct file_operations *fops) |
1da177e4 LT |
659 | { |
660 | memset(cdev, 0, sizeof *cdev); | |
661 | INIT_LIST_HEAD(&cdev->list); | |
f9cb074b | 662 | kobject_init(&cdev->kobj, &ktype_cdev_default); |
1da177e4 LT |
663 | cdev->ops = fops; |
664 | } | |
665 | ||
666 | static struct kobject *base_probe(dev_t dev, int *part, void *data) | |
667 | { | |
668 | if (request_module("char-major-%d-%d", MAJOR(dev), MINOR(dev)) > 0) | |
669 | /* Make old-style 2.4 aliases work */ | |
670 | request_module("char-major-%d", MAJOR(dev)); | |
671 | return NULL; | |
672 | } | |
673 | ||
674 | void __init chrdev_init(void) | |
675 | { | |
676 | cdev_map = kobj_map_init(base_probe, &chrdevs_lock); | |
677 | } | |
678 | ||
679 | ||
680 | /* Let modules do char dev stuff */ | |
681 | EXPORT_SYMBOL(register_chrdev_region); | |
682 | EXPORT_SYMBOL(unregister_chrdev_region); | |
683 | EXPORT_SYMBOL(alloc_chrdev_region); | |
684 | EXPORT_SYMBOL(cdev_init); | |
685 | EXPORT_SYMBOL(cdev_alloc); | |
686 | EXPORT_SYMBOL(cdev_del); | |
687 | EXPORT_SYMBOL(cdev_add); | |
233ed09d LG |
688 | EXPORT_SYMBOL(cdev_set_parent); |
689 | EXPORT_SYMBOL(cdev_device_add); | |
690 | EXPORT_SYMBOL(cdev_device_del); | |
1905b1bf TH |
691 | EXPORT_SYMBOL(__register_chrdev); |
692 | EXPORT_SYMBOL(__unregister_chrdev); |