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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 LT |
27 | |
28 | static struct kobj_map *cdev_map; | |
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 | ||
70 | for (i = ARRAY_SIZE(chrdevs)-1; i > CHRDEV_MAJOR_DYN_END; i--) { | |
71 | if (chrdevs[i] == NULL) | |
72 | return i; | |
73 | } | |
74 | ||
75 | for (i = CHRDEV_MAJOR_DYN_EXT_START; | |
76 | i > CHRDEV_MAJOR_DYN_EXT_END; i--) { | |
77 | for (cd = chrdevs[major_to_index(i)]; cd; cd = cd->next) | |
78 | if (cd->major == i) | |
79 | break; | |
80 | ||
81 | if (cd == NULL || cd->major != i) | |
82 | return i; | |
83 | } | |
84 | ||
85 | return -EBUSY; | |
86 | } | |
87 | ||
1da177e4 LT |
88 | /* |
89 | * Register a single major with a specified minor range. | |
90 | * | |
91 | * If major == 0 this functions will dynamically allocate a major and return | |
92 | * its number. | |
93 | * | |
94 | * If major > 0 this function will attempt to reserve the passed range of | |
95 | * minors and will return zero on success. | |
96 | * | |
97 | * Returns a -ve errno on failure. | |
98 | */ | |
99 | static struct char_device_struct * | |
100 | __register_chrdev_region(unsigned int major, unsigned int baseminor, | |
101 | int minorct, const char *name) | |
102 | { | |
103 | struct char_device_struct *cd, **cp; | |
104 | int ret = 0; | |
105 | int i; | |
106 | ||
11b0b5ab | 107 | cd = kzalloc(sizeof(struct char_device_struct), GFP_KERNEL); |
1da177e4 LT |
108 | if (cd == NULL) |
109 | return ERR_PTR(-ENOMEM); | |
110 | ||
58383af6 | 111 | mutex_lock(&chrdevs_lock); |
1da177e4 | 112 | |
1da177e4 | 113 | if (major == 0) { |
a5d31a3f LG |
114 | ret = find_dynamic_major(); |
115 | if (ret < 0) { | |
116 | pr_err("CHRDEV \"%s\" dynamic allocation region is full\n", | |
117 | name); | |
1da177e4 LT |
118 | goto out; |
119 | } | |
a5d31a3f | 120 | major = ret; |
1da177e4 LT |
121 | } |
122 | ||
8a932f73 LG |
123 | if (major >= CHRDEV_MAJOR_MAX) { |
124 | pr_err("CHRDEV \"%s\" major requested (%d) is greater than the maximum (%d)\n", | |
125 | name, major, CHRDEV_MAJOR_MAX); | |
126 | ret = -EINVAL; | |
127 | goto out; | |
128 | } | |
129 | ||
1da177e4 LT |
130 | cd->major = major; |
131 | cd->baseminor = baseminor; | |
132 | cd->minorct = minorct; | |
8c401888 | 133 | strlcpy(cd->name, name, sizeof(cd->name)); |
1da177e4 LT |
134 | |
135 | i = major_to_index(major); | |
136 | ||
137 | for (cp = &chrdevs[i]; *cp; cp = &(*cp)->next) | |
138 | if ((*cp)->major > major || | |
01d553d0 AW |
139 | ((*cp)->major == major && |
140 | (((*cp)->baseminor >= baseminor) || | |
141 | ((*cp)->baseminor + (*cp)->minorct > baseminor)))) | |
1da177e4 | 142 | break; |
01d553d0 AW |
143 | |
144 | /* Check for overlapping minor ranges. */ | |
145 | if (*cp && (*cp)->major == major) { | |
146 | int old_min = (*cp)->baseminor; | |
147 | int old_max = (*cp)->baseminor + (*cp)->minorct - 1; | |
148 | int new_min = baseminor; | |
149 | int new_max = baseminor + minorct - 1; | |
150 | ||
151 | /* New driver overlaps from the left. */ | |
152 | if (new_max >= old_min && new_max <= old_max) { | |
153 | ret = -EBUSY; | |
154 | goto out; | |
155 | } | |
156 | ||
157 | /* New driver overlaps from the right. */ | |
158 | if (new_min <= old_max && new_min >= old_min) { | |
159 | ret = -EBUSY; | |
160 | goto out; | |
161 | } | |
a7b4c856 CX |
162 | |
163 | if (new_min < old_min && new_max > old_max) { | |
164 | ret = -EBUSY; | |
165 | goto out; | |
166 | } | |
167 | ||
1da177e4 | 168 | } |
01d553d0 | 169 | |
1da177e4 LT |
170 | cd->next = *cp; |
171 | *cp = cd; | |
58383af6 | 172 | mutex_unlock(&chrdevs_lock); |
1da177e4 LT |
173 | return cd; |
174 | out: | |
58383af6 | 175 | mutex_unlock(&chrdevs_lock); |
1da177e4 LT |
176 | kfree(cd); |
177 | return ERR_PTR(ret); | |
178 | } | |
179 | ||
180 | static struct char_device_struct * | |
181 | __unregister_chrdev_region(unsigned major, unsigned baseminor, int minorct) | |
182 | { | |
183 | struct char_device_struct *cd = NULL, **cp; | |
184 | int i = major_to_index(major); | |
185 | ||
58383af6 | 186 | mutex_lock(&chrdevs_lock); |
1da177e4 LT |
187 | for (cp = &chrdevs[i]; *cp; cp = &(*cp)->next) |
188 | if ((*cp)->major == major && | |
189 | (*cp)->baseminor == baseminor && | |
190 | (*cp)->minorct == minorct) | |
191 | break; | |
192 | if (*cp) { | |
193 | cd = *cp; | |
194 | *cp = cd->next; | |
195 | } | |
58383af6 | 196 | mutex_unlock(&chrdevs_lock); |
1da177e4 LT |
197 | return cd; |
198 | } | |
199 | ||
cf3e43db JC |
200 | /** |
201 | * register_chrdev_region() - register a range of device numbers | |
202 | * @from: the first in the desired range of device numbers; must include | |
203 | * the major number. | |
204 | * @count: the number of consecutive device numbers required | |
205 | * @name: the name of the device or driver. | |
206 | * | |
207 | * Return value is zero on success, a negative error code on failure. | |
208 | */ | |
1da177e4 LT |
209 | int register_chrdev_region(dev_t from, unsigned count, const char *name) |
210 | { | |
211 | struct char_device_struct *cd; | |
212 | dev_t to = from + count; | |
213 | dev_t n, next; | |
214 | ||
215 | for (n = from; n < to; n = next) { | |
216 | next = MKDEV(MAJOR(n)+1, 0); | |
217 | if (next > to) | |
218 | next = to; | |
219 | cd = __register_chrdev_region(MAJOR(n), MINOR(n), | |
220 | next - n, name); | |
221 | if (IS_ERR(cd)) | |
222 | goto fail; | |
223 | } | |
224 | return 0; | |
225 | fail: | |
226 | to = n; | |
227 | for (n = from; n < to; n = next) { | |
228 | next = MKDEV(MAJOR(n)+1, 0); | |
229 | kfree(__unregister_chrdev_region(MAJOR(n), MINOR(n), next - n)); | |
230 | } | |
231 | return PTR_ERR(cd); | |
232 | } | |
233 | ||
cf3e43db JC |
234 | /** |
235 | * alloc_chrdev_region() - register a range of char device numbers | |
236 | * @dev: output parameter for first assigned number | |
237 | * @baseminor: first of the requested range of minor numbers | |
238 | * @count: the number of minor numbers required | |
239 | * @name: the name of the associated device or driver | |
240 | * | |
241 | * Allocates a range of char device numbers. The major number will be | |
242 | * chosen dynamically, and returned (along with the first minor number) | |
243 | * in @dev. Returns zero or a negative error code. | |
244 | */ | |
1da177e4 LT |
245 | int alloc_chrdev_region(dev_t *dev, unsigned baseminor, unsigned count, |
246 | const char *name) | |
247 | { | |
248 | struct char_device_struct *cd; | |
249 | cd = __register_chrdev_region(0, baseminor, count, name); | |
250 | if (IS_ERR(cd)) | |
251 | return PTR_ERR(cd); | |
252 | *dev = MKDEV(cd->major, cd->baseminor); | |
253 | return 0; | |
254 | } | |
255 | ||
d247e2c6 | 256 | /** |
1905b1bf | 257 | * __register_chrdev() - create and register a cdev occupying a range of minors |
d247e2c6 | 258 | * @major: major device number or 0 for dynamic allocation |
1905b1bf TH |
259 | * @baseminor: first of the requested range of minor numbers |
260 | * @count: the number of minor numbers required | |
d247e2c6 REB |
261 | * @name: name of this range of devices |
262 | * @fops: file operations associated with this devices | |
263 | * | |
264 | * If @major == 0 this functions will dynamically allocate a major and return | |
265 | * its number. | |
266 | * | |
267 | * If @major > 0 this function will attempt to reserve a device with the given | |
268 | * major number and will return zero on success. | |
269 | * | |
270 | * Returns a -ve errno on failure. | |
271 | * | |
272 | * The name of this device has nothing to do with the name of the device in | |
273 | * /dev. It only helps to keep track of the different owners of devices. If | |
274 | * your module name has only one type of devices it's ok to use e.g. the name | |
275 | * of the module here. | |
d247e2c6 | 276 | */ |
1905b1bf TH |
277 | int __register_chrdev(unsigned int major, unsigned int baseminor, |
278 | unsigned int count, const char *name, | |
279 | const struct file_operations *fops) | |
1da177e4 LT |
280 | { |
281 | struct char_device_struct *cd; | |
282 | struct cdev *cdev; | |
1da177e4 LT |
283 | int err = -ENOMEM; |
284 | ||
1905b1bf | 285 | cd = __register_chrdev_region(major, baseminor, count, name); |
1da177e4 LT |
286 | if (IS_ERR(cd)) |
287 | return PTR_ERR(cd); | |
1ff97647 | 288 | |
1da177e4 LT |
289 | cdev = cdev_alloc(); |
290 | if (!cdev) | |
291 | goto out2; | |
292 | ||
293 | cdev->owner = fops->owner; | |
294 | cdev->ops = fops; | |
295 | kobject_set_name(&cdev->kobj, "%s", name); | |
1ff97647 | 296 | |
1905b1bf | 297 | err = cdev_add(cdev, MKDEV(cd->major, baseminor), count); |
1da177e4 LT |
298 | if (err) |
299 | goto out; | |
300 | ||
301 | cd->cdev = cdev; | |
302 | ||
303 | return major ? 0 : cd->major; | |
304 | out: | |
305 | kobject_put(&cdev->kobj); | |
306 | out2: | |
1905b1bf | 307 | kfree(__unregister_chrdev_region(cd->major, baseminor, count)); |
1da177e4 LT |
308 | return err; |
309 | } | |
310 | ||
cf3e43db | 311 | /** |
594069bc | 312 | * unregister_chrdev_region() - unregister a range of device numbers |
cf3e43db JC |
313 | * @from: the first in the range of numbers to unregister |
314 | * @count: the number of device numbers to unregister | |
315 | * | |
316 | * This function will unregister a range of @count device numbers, | |
317 | * starting with @from. The caller should normally be the one who | |
318 | * allocated those numbers in the first place... | |
319 | */ | |
1da177e4 LT |
320 | void unregister_chrdev_region(dev_t from, unsigned count) |
321 | { | |
322 | dev_t to = from + count; | |
323 | dev_t n, next; | |
324 | ||
325 | for (n = from; n < to; n = next) { | |
326 | next = MKDEV(MAJOR(n)+1, 0); | |
327 | if (next > to) | |
328 | next = to; | |
329 | kfree(__unregister_chrdev_region(MAJOR(n), MINOR(n), next - n)); | |
330 | } | |
331 | } | |
332 | ||
1905b1bf TH |
333 | /** |
334 | * __unregister_chrdev - unregister and destroy a cdev | |
335 | * @major: major device number | |
336 | * @baseminor: first of the range of minor numbers | |
337 | * @count: the number of minor numbers this cdev is occupying | |
338 | * @name: name of this range of devices | |
339 | * | |
340 | * Unregister and destroy the cdev occupying the region described by | |
341 | * @major, @baseminor and @count. This function undoes what | |
342 | * __register_chrdev() did. | |
343 | */ | |
344 | void __unregister_chrdev(unsigned int major, unsigned int baseminor, | |
345 | unsigned int count, const char *name) | |
1da177e4 LT |
346 | { |
347 | struct char_device_struct *cd; | |
1905b1bf TH |
348 | |
349 | cd = __unregister_chrdev_region(major, baseminor, count); | |
1da177e4 LT |
350 | if (cd && cd->cdev) |
351 | cdev_del(cd->cdev); | |
352 | kfree(cd); | |
1da177e4 LT |
353 | } |
354 | ||
355 | static DEFINE_SPINLOCK(cdev_lock); | |
356 | ||
357 | static struct kobject *cdev_get(struct cdev *p) | |
358 | { | |
359 | struct module *owner = p->owner; | |
360 | struct kobject *kobj; | |
361 | ||
362 | if (owner && !try_module_get(owner)) | |
363 | return NULL; | |
10929985 | 364 | kobj = kobject_get_unless_zero(&p->kobj); |
1da177e4 LT |
365 | if (!kobj) |
366 | module_put(owner); | |
367 | return kobj; | |
368 | } | |
369 | ||
370 | void cdev_put(struct cdev *p) | |
371 | { | |
372 | if (p) { | |
7da6844c | 373 | struct module *owner = p->owner; |
1da177e4 | 374 | kobject_put(&p->kobj); |
7da6844c | 375 | module_put(owner); |
1da177e4 LT |
376 | } |
377 | } | |
378 | ||
379 | /* | |
380 | * Called every time a character special file is opened | |
381 | */ | |
922f9cfa | 382 | static int chrdev_open(struct inode *inode, struct file *filp) |
1da177e4 | 383 | { |
e84f9e57 | 384 | const struct file_operations *fops; |
1da177e4 LT |
385 | struct cdev *p; |
386 | struct cdev *new = NULL; | |
387 | int ret = 0; | |
388 | ||
389 | spin_lock(&cdev_lock); | |
390 | p = inode->i_cdev; | |
391 | if (!p) { | |
392 | struct kobject *kobj; | |
393 | int idx; | |
394 | spin_unlock(&cdev_lock); | |
395 | kobj = kobj_lookup(cdev_map, inode->i_rdev, &idx); | |
396 | if (!kobj) | |
397 | return -ENXIO; | |
398 | new = container_of(kobj, struct cdev, kobj); | |
399 | spin_lock(&cdev_lock); | |
a30427d9 JC |
400 | /* Check i_cdev again in case somebody beat us to it while |
401 | we dropped the lock. */ | |
1da177e4 LT |
402 | p = inode->i_cdev; |
403 | if (!p) { | |
404 | inode->i_cdev = p = new; | |
1da177e4 LT |
405 | list_add(&inode->i_devices, &p->list); |
406 | new = NULL; | |
407 | } else if (!cdev_get(p)) | |
408 | ret = -ENXIO; | |
409 | } else if (!cdev_get(p)) | |
410 | ret = -ENXIO; | |
411 | spin_unlock(&cdev_lock); | |
412 | cdev_put(new); | |
413 | if (ret) | |
414 | return ret; | |
a518ab93 CH |
415 | |
416 | ret = -ENXIO; | |
e84f9e57 AV |
417 | fops = fops_get(p->ops); |
418 | if (!fops) | |
a518ab93 CH |
419 | goto out_cdev_put; |
420 | ||
e84f9e57 | 421 | replace_fops(filp, fops); |
a518ab93 | 422 | if (filp->f_op->open) { |
1ff97647 | 423 | ret = filp->f_op->open(inode, filp); |
a518ab93 CH |
424 | if (ret) |
425 | goto out_cdev_put; | |
426 | } | |
427 | ||
428 | return 0; | |
429 | ||
430 | out_cdev_put: | |
431 | cdev_put(p); | |
1da177e4 LT |
432 | return ret; |
433 | } | |
434 | ||
435 | void cd_forget(struct inode *inode) | |
436 | { | |
437 | spin_lock(&cdev_lock); | |
438 | list_del_init(&inode->i_devices); | |
439 | inode->i_cdev = NULL; | |
3bc52c45 | 440 | inode->i_mapping = &inode->i_data; |
1da177e4 LT |
441 | spin_unlock(&cdev_lock); |
442 | } | |
443 | ||
75c96f85 | 444 | static void cdev_purge(struct cdev *cdev) |
1da177e4 LT |
445 | { |
446 | spin_lock(&cdev_lock); | |
447 | while (!list_empty(&cdev->list)) { | |
448 | struct inode *inode; | |
449 | inode = container_of(cdev->list.next, struct inode, i_devices); | |
450 | list_del_init(&inode->i_devices); | |
451 | inode->i_cdev = NULL; | |
452 | } | |
453 | spin_unlock(&cdev_lock); | |
454 | } | |
455 | ||
456 | /* | |
457 | * Dummy default file-operations: the only thing this does | |
458 | * is contain the open that then fills in the correct operations | |
459 | * depending on the special file... | |
460 | */ | |
4b6f5d20 | 461 | const struct file_operations def_chr_fops = { |
1da177e4 | 462 | .open = chrdev_open, |
6038f373 | 463 | .llseek = noop_llseek, |
1da177e4 LT |
464 | }; |
465 | ||
466 | static struct kobject *exact_match(dev_t dev, int *part, void *data) | |
467 | { | |
468 | struct cdev *p = data; | |
469 | return &p->kobj; | |
470 | } | |
471 | ||
472 | static int exact_lock(dev_t dev, void *data) | |
473 | { | |
474 | struct cdev *p = data; | |
475 | return cdev_get(p) ? 0 : -1; | |
476 | } | |
477 | ||
cf3e43db JC |
478 | /** |
479 | * cdev_add() - add a char device to the system | |
480 | * @p: the cdev structure for the device | |
481 | * @dev: the first device number for which this device is responsible | |
482 | * @count: the number of consecutive minor numbers corresponding to this | |
483 | * device | |
484 | * | |
485 | * cdev_add() adds the device represented by @p to the system, making it | |
486 | * live immediately. A negative error code is returned on failure. | |
487 | */ | |
1da177e4 LT |
488 | int cdev_add(struct cdev *p, dev_t dev, unsigned count) |
489 | { | |
2f0157f1 DT |
490 | int error; |
491 | ||
1da177e4 LT |
492 | p->dev = dev; |
493 | p->count = count; | |
2f0157f1 DT |
494 | |
495 | error = kobj_map(cdev_map, dev, count, NULL, | |
496 | exact_match, exact_lock, p); | |
497 | if (error) | |
498 | return error; | |
499 | ||
500 | kobject_get(p->kobj.parent); | |
501 | ||
502 | return 0; | |
1da177e4 LT |
503 | } |
504 | ||
233ed09d LG |
505 | /** |
506 | * cdev_set_parent() - set the parent kobject for a char device | |
507 | * @p: the cdev structure | |
508 | * @kobj: the kobject to take a reference to | |
509 | * | |
510 | * cdev_set_parent() sets a parent kobject which will be referenced | |
511 | * appropriately so the parent is not freed before the cdev. This | |
512 | * should be called before cdev_add. | |
513 | */ | |
514 | void cdev_set_parent(struct cdev *p, struct kobject *kobj) | |
515 | { | |
516 | WARN_ON(!kobj->state_initialized); | |
517 | p->kobj.parent = kobj; | |
518 | } | |
519 | ||
520 | /** | |
521 | * cdev_device_add() - add a char device and it's corresponding | |
522 | * struct device, linkink | |
523 | * @dev: the device structure | |
524 | * @cdev: the cdev structure | |
525 | * | |
526 | * cdev_device_add() adds the char device represented by @cdev to the system, | |
527 | * just as cdev_add does. It then adds @dev to the system using device_add | |
528 | * The dev_t for the char device will be taken from the struct device which | |
529 | * needs to be initialized first. This helper function correctly takes a | |
530 | * reference to the parent device so the parent will not get released until | |
531 | * all references to the cdev are released. | |
532 | * | |
533 | * This helper uses dev->devt for the device number. If it is not set | |
534 | * it will not add the cdev and it will be equivalent to device_add. | |
535 | * | |
536 | * This function should be used whenever the struct cdev and the | |
537 | * struct device are members of the same structure whose lifetime is | |
538 | * managed by the struct device. | |
539 | * | |
540 | * NOTE: Callers must assume that userspace was able to open the cdev and | |
541 | * can call cdev fops callbacks at any time, even if this function fails. | |
542 | */ | |
543 | int cdev_device_add(struct cdev *cdev, struct device *dev) | |
544 | { | |
545 | int rc = 0; | |
546 | ||
547 | if (dev->devt) { | |
548 | cdev_set_parent(cdev, &dev->kobj); | |
549 | ||
550 | rc = cdev_add(cdev, dev->devt, 1); | |
551 | if (rc) | |
552 | return rc; | |
553 | } | |
554 | ||
555 | rc = device_add(dev); | |
556 | if (rc) | |
557 | cdev_del(cdev); | |
558 | ||
559 | return rc; | |
560 | } | |
561 | ||
562 | /** | |
563 | * cdev_device_del() - inverse of cdev_device_add | |
564 | * @dev: the device structure | |
565 | * @cdev: the cdev structure | |
566 | * | |
567 | * cdev_device_del() is a helper function to call cdev_del and device_del. | |
568 | * It should be used whenever cdev_device_add is used. | |
569 | * | |
570 | * If dev->devt is not set it will not remove the cdev and will be equivalent | |
571 | * to device_del. | |
572 | * | |
573 | * NOTE: This guarantees that associated sysfs callbacks are not running | |
574 | * or runnable, however any cdevs already open will remain and their fops | |
575 | * will still be callable even after this function returns. | |
576 | */ | |
577 | void cdev_device_del(struct cdev *cdev, struct device *dev) | |
578 | { | |
579 | device_del(dev); | |
580 | if (dev->devt) | |
581 | cdev_del(cdev); | |
582 | } | |
583 | ||
1da177e4 LT |
584 | static void cdev_unmap(dev_t dev, unsigned count) |
585 | { | |
586 | kobj_unmap(cdev_map, dev, count); | |
587 | } | |
588 | ||
cf3e43db JC |
589 | /** |
590 | * cdev_del() - remove a cdev from the system | |
591 | * @p: the cdev structure to be removed | |
592 | * | |
593 | * cdev_del() removes @p from the system, possibly freeing the structure | |
594 | * itself. | |
233ed09d LG |
595 | * |
596 | * NOTE: This guarantees that cdev device will no longer be able to be | |
597 | * opened, however any cdevs already open will remain and their fops will | |
598 | * still be callable even after cdev_del returns. | |
cf3e43db | 599 | */ |
1da177e4 LT |
600 | void cdev_del(struct cdev *p) |
601 | { | |
602 | cdev_unmap(p->dev, p->count); | |
603 | kobject_put(&p->kobj); | |
604 | } | |
605 | ||
606 | ||
607 | static void cdev_default_release(struct kobject *kobj) | |
608 | { | |
609 | struct cdev *p = container_of(kobj, struct cdev, kobj); | |
2f0157f1 DT |
610 | struct kobject *parent = kobj->parent; |
611 | ||
1da177e4 | 612 | cdev_purge(p); |
2f0157f1 | 613 | kobject_put(parent); |
1da177e4 LT |
614 | } |
615 | ||
616 | static void cdev_dynamic_release(struct kobject *kobj) | |
617 | { | |
618 | struct cdev *p = container_of(kobj, struct cdev, kobj); | |
2f0157f1 DT |
619 | struct kobject *parent = kobj->parent; |
620 | ||
1da177e4 LT |
621 | cdev_purge(p); |
622 | kfree(p); | |
2f0157f1 | 623 | kobject_put(parent); |
1da177e4 LT |
624 | } |
625 | ||
626 | static struct kobj_type ktype_cdev_default = { | |
627 | .release = cdev_default_release, | |
628 | }; | |
629 | ||
630 | static struct kobj_type ktype_cdev_dynamic = { | |
631 | .release = cdev_dynamic_release, | |
632 | }; | |
633 | ||
cf3e43db JC |
634 | /** |
635 | * cdev_alloc() - allocate a cdev structure | |
636 | * | |
637 | * Allocates and returns a cdev structure, or NULL on failure. | |
638 | */ | |
1da177e4 LT |
639 | struct cdev *cdev_alloc(void) |
640 | { | |
11b0b5ab | 641 | struct cdev *p = kzalloc(sizeof(struct cdev), GFP_KERNEL); |
1da177e4 | 642 | if (p) { |
1da177e4 | 643 | INIT_LIST_HEAD(&p->list); |
f9cb074b | 644 | kobject_init(&p->kobj, &ktype_cdev_dynamic); |
1da177e4 LT |
645 | } |
646 | return p; | |
647 | } | |
648 | ||
cf3e43db JC |
649 | /** |
650 | * cdev_init() - initialize a cdev structure | |
651 | * @cdev: the structure to initialize | |
652 | * @fops: the file_operations for this device | |
653 | * | |
654 | * Initializes @cdev, remembering @fops, making it ready to add to the | |
655 | * system with cdev_add(). | |
656 | */ | |
99ac48f5 | 657 | void cdev_init(struct cdev *cdev, const struct file_operations *fops) |
1da177e4 LT |
658 | { |
659 | memset(cdev, 0, sizeof *cdev); | |
660 | INIT_LIST_HEAD(&cdev->list); | |
f9cb074b | 661 | kobject_init(&cdev->kobj, &ktype_cdev_default); |
1da177e4 LT |
662 | cdev->ops = fops; |
663 | } | |
664 | ||
665 | static struct kobject *base_probe(dev_t dev, int *part, void *data) | |
666 | { | |
667 | if (request_module("char-major-%d-%d", MAJOR(dev), MINOR(dev)) > 0) | |
668 | /* Make old-style 2.4 aliases work */ | |
669 | request_module("char-major-%d", MAJOR(dev)); | |
670 | return NULL; | |
671 | } | |
672 | ||
673 | void __init chrdev_init(void) | |
674 | { | |
675 | cdev_map = kobj_map_init(base_probe, &chrdevs_lock); | |
676 | } | |
677 | ||
678 | ||
679 | /* Let modules do char dev stuff */ | |
680 | EXPORT_SYMBOL(register_chrdev_region); | |
681 | EXPORT_SYMBOL(unregister_chrdev_region); | |
682 | EXPORT_SYMBOL(alloc_chrdev_region); | |
683 | EXPORT_SYMBOL(cdev_init); | |
684 | EXPORT_SYMBOL(cdev_alloc); | |
685 | EXPORT_SYMBOL(cdev_del); | |
686 | EXPORT_SYMBOL(cdev_add); | |
233ed09d LG |
687 | EXPORT_SYMBOL(cdev_set_parent); |
688 | EXPORT_SYMBOL(cdev_device_add); | |
689 | EXPORT_SYMBOL(cdev_device_del); | |
1905b1bf TH |
690 | EXPORT_SYMBOL(__register_chrdev); |
691 | EXPORT_SYMBOL(__unregister_chrdev); |