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Commit | Line | Data |
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1da177e4 LT |
1 | /* |
2 | * linux/fs/char_dev.c | |
3 | * | |
4 | * Copyright (C) 1991, 1992 Linus Torvalds | |
5 | */ | |
6 | ||
1da177e4 LT |
7 | #include <linux/init.h> |
8 | #include <linux/fs.h> | |
b446b60e | 9 | #include <linux/kdev_t.h> |
1da177e4 LT |
10 | #include <linux/slab.h> |
11 | #include <linux/string.h> | |
12 | ||
13 | #include <linux/major.h> | |
14 | #include <linux/errno.h> | |
15 | #include <linux/module.h> | |
68eef3b4 | 16 | #include <linux/seq_file.h> |
1da177e4 LT |
17 | |
18 | #include <linux/kobject.h> | |
19 | #include <linux/kobj_map.h> | |
20 | #include <linux/cdev.h> | |
58383af6 | 21 | #include <linux/mutex.h> |
5da6185b | 22 | #include <linux/backing-dev.h> |
31d1d48e | 23 | #include <linux/tty.h> |
1da177e4 | 24 | |
07f3f05c | 25 | #include "internal.h" |
1da177e4 LT |
26 | |
27 | static struct kobj_map *cdev_map; | |
28 | ||
58383af6 | 29 | static DEFINE_MUTEX(chrdevs_lock); |
1da177e4 LT |
30 | |
31 | static struct char_device_struct { | |
32 | struct char_device_struct *next; | |
33 | unsigned int major; | |
34 | unsigned int baseminor; | |
35 | int minorct; | |
7170be5f | 36 | char name[64]; |
1da177e4 | 37 | struct cdev *cdev; /* will die */ |
68eef3b4 | 38 | } *chrdevs[CHRDEV_MAJOR_HASH_SIZE]; |
1da177e4 LT |
39 | |
40 | /* index in the above */ | |
e61eb2e9 | 41 | static inline int major_to_index(unsigned major) |
1da177e4 | 42 | { |
68eef3b4 | 43 | return major % CHRDEV_MAJOR_HASH_SIZE; |
7170be5f NH |
44 | } |
45 | ||
68eef3b4 | 46 | #ifdef CONFIG_PROC_FS |
7170be5f | 47 | |
68eef3b4 | 48 | void chrdev_show(struct seq_file *f, off_t offset) |
7170be5f NH |
49 | { |
50 | struct char_device_struct *cd; | |
7170be5f | 51 | |
68eef3b4 JK |
52 | if (offset < CHRDEV_MAJOR_HASH_SIZE) { |
53 | mutex_lock(&chrdevs_lock); | |
54 | for (cd = chrdevs[offset]; cd; cd = cd->next) | |
55 | seq_printf(f, "%3d %s\n", cd->major, cd->name); | |
56 | mutex_unlock(&chrdevs_lock); | |
1da177e4 | 57 | } |
7170be5f NH |
58 | } |
59 | ||
68eef3b4 | 60 | #endif /* CONFIG_PROC_FS */ |
1da177e4 | 61 | |
a5d31a3f LG |
62 | static int find_dynamic_major(void) |
63 | { | |
64 | int i; | |
65 | struct char_device_struct *cd; | |
66 | ||
67 | for (i = ARRAY_SIZE(chrdevs)-1; i > CHRDEV_MAJOR_DYN_END; i--) { | |
68 | if (chrdevs[i] == NULL) | |
69 | return i; | |
70 | } | |
71 | ||
72 | for (i = CHRDEV_MAJOR_DYN_EXT_START; | |
73 | i > CHRDEV_MAJOR_DYN_EXT_END; i--) { | |
74 | for (cd = chrdevs[major_to_index(i)]; cd; cd = cd->next) | |
75 | if (cd->major == i) | |
76 | break; | |
77 | ||
78 | if (cd == NULL || cd->major != i) | |
79 | return i; | |
80 | } | |
81 | ||
82 | return -EBUSY; | |
83 | } | |
84 | ||
1da177e4 LT |
85 | /* |
86 | * Register a single major with a specified minor range. | |
87 | * | |
88 | * If major == 0 this functions will dynamically allocate a major and return | |
89 | * its number. | |
90 | * | |
91 | * If major > 0 this function will attempt to reserve the passed range of | |
92 | * minors and will return zero on success. | |
93 | * | |
94 | * Returns a -ve errno on failure. | |
95 | */ | |
96 | static struct char_device_struct * | |
97 | __register_chrdev_region(unsigned int major, unsigned int baseminor, | |
98 | int minorct, const char *name) | |
99 | { | |
100 | struct char_device_struct *cd, **cp; | |
101 | int ret = 0; | |
102 | int i; | |
103 | ||
11b0b5ab | 104 | cd = kzalloc(sizeof(struct char_device_struct), GFP_KERNEL); |
1da177e4 LT |
105 | if (cd == NULL) |
106 | return ERR_PTR(-ENOMEM); | |
107 | ||
58383af6 | 108 | mutex_lock(&chrdevs_lock); |
1da177e4 | 109 | |
1da177e4 | 110 | if (major == 0) { |
a5d31a3f LG |
111 | ret = find_dynamic_major(); |
112 | if (ret < 0) { | |
113 | pr_err("CHRDEV \"%s\" dynamic allocation region is full\n", | |
114 | name); | |
1da177e4 LT |
115 | goto out; |
116 | } | |
a5d31a3f | 117 | major = ret; |
1da177e4 LT |
118 | } |
119 | ||
120 | cd->major = major; | |
121 | cd->baseminor = baseminor; | |
122 | cd->minorct = minorct; | |
8c401888 | 123 | strlcpy(cd->name, name, sizeof(cd->name)); |
1da177e4 LT |
124 | |
125 | i = major_to_index(major); | |
126 | ||
127 | for (cp = &chrdevs[i]; *cp; cp = &(*cp)->next) | |
128 | if ((*cp)->major > major || | |
01d553d0 AW |
129 | ((*cp)->major == major && |
130 | (((*cp)->baseminor >= baseminor) || | |
131 | ((*cp)->baseminor + (*cp)->minorct > baseminor)))) | |
1da177e4 | 132 | break; |
01d553d0 AW |
133 | |
134 | /* Check for overlapping minor ranges. */ | |
135 | if (*cp && (*cp)->major == major) { | |
136 | int old_min = (*cp)->baseminor; | |
137 | int old_max = (*cp)->baseminor + (*cp)->minorct - 1; | |
138 | int new_min = baseminor; | |
139 | int new_max = baseminor + minorct - 1; | |
140 | ||
141 | /* New driver overlaps from the left. */ | |
142 | if (new_max >= old_min && new_max <= old_max) { | |
143 | ret = -EBUSY; | |
144 | goto out; | |
145 | } | |
146 | ||
147 | /* New driver overlaps from the right. */ | |
148 | if (new_min <= old_max && new_min >= old_min) { | |
149 | ret = -EBUSY; | |
150 | goto out; | |
151 | } | |
1da177e4 | 152 | } |
01d553d0 | 153 | |
1da177e4 LT |
154 | cd->next = *cp; |
155 | *cp = cd; | |
58383af6 | 156 | mutex_unlock(&chrdevs_lock); |
1da177e4 LT |
157 | return cd; |
158 | out: | |
58383af6 | 159 | mutex_unlock(&chrdevs_lock); |
1da177e4 LT |
160 | kfree(cd); |
161 | return ERR_PTR(ret); | |
162 | } | |
163 | ||
164 | static struct char_device_struct * | |
165 | __unregister_chrdev_region(unsigned major, unsigned baseminor, int minorct) | |
166 | { | |
167 | struct char_device_struct *cd = NULL, **cp; | |
168 | int i = major_to_index(major); | |
169 | ||
58383af6 | 170 | mutex_lock(&chrdevs_lock); |
1da177e4 LT |
171 | for (cp = &chrdevs[i]; *cp; cp = &(*cp)->next) |
172 | if ((*cp)->major == major && | |
173 | (*cp)->baseminor == baseminor && | |
174 | (*cp)->minorct == minorct) | |
175 | break; | |
176 | if (*cp) { | |
177 | cd = *cp; | |
178 | *cp = cd->next; | |
179 | } | |
58383af6 | 180 | mutex_unlock(&chrdevs_lock); |
1da177e4 LT |
181 | return cd; |
182 | } | |
183 | ||
cf3e43db JC |
184 | /** |
185 | * register_chrdev_region() - register a range of device numbers | |
186 | * @from: the first in the desired range of device numbers; must include | |
187 | * the major number. | |
188 | * @count: the number of consecutive device numbers required | |
189 | * @name: the name of the device or driver. | |
190 | * | |
191 | * Return value is zero on success, a negative error code on failure. | |
192 | */ | |
1da177e4 LT |
193 | int register_chrdev_region(dev_t from, unsigned count, const char *name) |
194 | { | |
195 | struct char_device_struct *cd; | |
196 | dev_t to = from + count; | |
197 | dev_t n, next; | |
198 | ||
199 | for (n = from; n < to; n = next) { | |
200 | next = MKDEV(MAJOR(n)+1, 0); | |
201 | if (next > to) | |
202 | next = to; | |
203 | cd = __register_chrdev_region(MAJOR(n), MINOR(n), | |
204 | next - n, name); | |
205 | if (IS_ERR(cd)) | |
206 | goto fail; | |
207 | } | |
208 | return 0; | |
209 | fail: | |
210 | to = n; | |
211 | for (n = from; n < to; n = next) { | |
212 | next = MKDEV(MAJOR(n)+1, 0); | |
213 | kfree(__unregister_chrdev_region(MAJOR(n), MINOR(n), next - n)); | |
214 | } | |
215 | return PTR_ERR(cd); | |
216 | } | |
217 | ||
cf3e43db JC |
218 | /** |
219 | * alloc_chrdev_region() - register a range of char device numbers | |
220 | * @dev: output parameter for first assigned number | |
221 | * @baseminor: first of the requested range of minor numbers | |
222 | * @count: the number of minor numbers required | |
223 | * @name: the name of the associated device or driver | |
224 | * | |
225 | * Allocates a range of char device numbers. The major number will be | |
226 | * chosen dynamically, and returned (along with the first minor number) | |
227 | * in @dev. Returns zero or a negative error code. | |
228 | */ | |
1da177e4 LT |
229 | int alloc_chrdev_region(dev_t *dev, unsigned baseminor, unsigned count, |
230 | const char *name) | |
231 | { | |
232 | struct char_device_struct *cd; | |
233 | cd = __register_chrdev_region(0, baseminor, count, name); | |
234 | if (IS_ERR(cd)) | |
235 | return PTR_ERR(cd); | |
236 | *dev = MKDEV(cd->major, cd->baseminor); | |
237 | return 0; | |
238 | } | |
239 | ||
d247e2c6 | 240 | /** |
1905b1bf | 241 | * __register_chrdev() - create and register a cdev occupying a range of minors |
d247e2c6 | 242 | * @major: major device number or 0 for dynamic allocation |
1905b1bf TH |
243 | * @baseminor: first of the requested range of minor numbers |
244 | * @count: the number of minor numbers required | |
d247e2c6 REB |
245 | * @name: name of this range of devices |
246 | * @fops: file operations associated with this devices | |
247 | * | |
248 | * If @major == 0 this functions will dynamically allocate a major and return | |
249 | * its number. | |
250 | * | |
251 | * If @major > 0 this function will attempt to reserve a device with the given | |
252 | * major number and will return zero on success. | |
253 | * | |
254 | * Returns a -ve errno on failure. | |
255 | * | |
256 | * The name of this device has nothing to do with the name of the device in | |
257 | * /dev. It only helps to keep track of the different owners of devices. If | |
258 | * your module name has only one type of devices it's ok to use e.g. the name | |
259 | * of the module here. | |
d247e2c6 | 260 | */ |
1905b1bf TH |
261 | int __register_chrdev(unsigned int major, unsigned int baseminor, |
262 | unsigned int count, const char *name, | |
263 | const struct file_operations *fops) | |
1da177e4 LT |
264 | { |
265 | struct char_device_struct *cd; | |
266 | struct cdev *cdev; | |
1da177e4 LT |
267 | int err = -ENOMEM; |
268 | ||
1905b1bf | 269 | cd = __register_chrdev_region(major, baseminor, count, name); |
1da177e4 LT |
270 | if (IS_ERR(cd)) |
271 | return PTR_ERR(cd); | |
1ff97647 | 272 | |
1da177e4 LT |
273 | cdev = cdev_alloc(); |
274 | if (!cdev) | |
275 | goto out2; | |
276 | ||
277 | cdev->owner = fops->owner; | |
278 | cdev->ops = fops; | |
279 | kobject_set_name(&cdev->kobj, "%s", name); | |
1ff97647 | 280 | |
1905b1bf | 281 | err = cdev_add(cdev, MKDEV(cd->major, baseminor), count); |
1da177e4 LT |
282 | if (err) |
283 | goto out; | |
284 | ||
285 | cd->cdev = cdev; | |
286 | ||
287 | return major ? 0 : cd->major; | |
288 | out: | |
289 | kobject_put(&cdev->kobj); | |
290 | out2: | |
1905b1bf | 291 | kfree(__unregister_chrdev_region(cd->major, baseminor, count)); |
1da177e4 LT |
292 | return err; |
293 | } | |
294 | ||
cf3e43db | 295 | /** |
594069bc | 296 | * unregister_chrdev_region() - unregister a range of device numbers |
cf3e43db JC |
297 | * @from: the first in the range of numbers to unregister |
298 | * @count: the number of device numbers to unregister | |
299 | * | |
300 | * This function will unregister a range of @count device numbers, | |
301 | * starting with @from. The caller should normally be the one who | |
302 | * allocated those numbers in the first place... | |
303 | */ | |
1da177e4 LT |
304 | void unregister_chrdev_region(dev_t from, unsigned count) |
305 | { | |
306 | dev_t to = from + count; | |
307 | dev_t n, next; | |
308 | ||
309 | for (n = from; n < to; n = next) { | |
310 | next = MKDEV(MAJOR(n)+1, 0); | |
311 | if (next > to) | |
312 | next = to; | |
313 | kfree(__unregister_chrdev_region(MAJOR(n), MINOR(n), next - n)); | |
314 | } | |
315 | } | |
316 | ||
1905b1bf TH |
317 | /** |
318 | * __unregister_chrdev - unregister and destroy a cdev | |
319 | * @major: major device number | |
320 | * @baseminor: first of the range of minor numbers | |
321 | * @count: the number of minor numbers this cdev is occupying | |
322 | * @name: name of this range of devices | |
323 | * | |
324 | * Unregister and destroy the cdev occupying the region described by | |
325 | * @major, @baseminor and @count. This function undoes what | |
326 | * __register_chrdev() did. | |
327 | */ | |
328 | void __unregister_chrdev(unsigned int major, unsigned int baseminor, | |
329 | unsigned int count, const char *name) | |
1da177e4 LT |
330 | { |
331 | struct char_device_struct *cd; | |
1905b1bf TH |
332 | |
333 | cd = __unregister_chrdev_region(major, baseminor, count); | |
1da177e4 LT |
334 | if (cd && cd->cdev) |
335 | cdev_del(cd->cdev); | |
336 | kfree(cd); | |
1da177e4 LT |
337 | } |
338 | ||
339 | static DEFINE_SPINLOCK(cdev_lock); | |
340 | ||
341 | static struct kobject *cdev_get(struct cdev *p) | |
342 | { | |
343 | struct module *owner = p->owner; | |
344 | struct kobject *kobj; | |
345 | ||
346 | if (owner && !try_module_get(owner)) | |
347 | return NULL; | |
348 | kobj = kobject_get(&p->kobj); | |
349 | if (!kobj) | |
350 | module_put(owner); | |
351 | return kobj; | |
352 | } | |
353 | ||
354 | void cdev_put(struct cdev *p) | |
355 | { | |
356 | if (p) { | |
7da6844c | 357 | struct module *owner = p->owner; |
1da177e4 | 358 | kobject_put(&p->kobj); |
7da6844c | 359 | module_put(owner); |
1da177e4 LT |
360 | } |
361 | } | |
362 | ||
363 | /* | |
364 | * Called every time a character special file is opened | |
365 | */ | |
922f9cfa | 366 | static int chrdev_open(struct inode *inode, struct file *filp) |
1da177e4 | 367 | { |
e84f9e57 | 368 | const struct file_operations *fops; |
1da177e4 LT |
369 | struct cdev *p; |
370 | struct cdev *new = NULL; | |
371 | int ret = 0; | |
372 | ||
373 | spin_lock(&cdev_lock); | |
374 | p = inode->i_cdev; | |
375 | if (!p) { | |
376 | struct kobject *kobj; | |
377 | int idx; | |
378 | spin_unlock(&cdev_lock); | |
379 | kobj = kobj_lookup(cdev_map, inode->i_rdev, &idx); | |
380 | if (!kobj) | |
381 | return -ENXIO; | |
382 | new = container_of(kobj, struct cdev, kobj); | |
383 | spin_lock(&cdev_lock); | |
a30427d9 JC |
384 | /* Check i_cdev again in case somebody beat us to it while |
385 | we dropped the lock. */ | |
1da177e4 LT |
386 | p = inode->i_cdev; |
387 | if (!p) { | |
388 | inode->i_cdev = p = new; | |
1da177e4 LT |
389 | list_add(&inode->i_devices, &p->list); |
390 | new = NULL; | |
391 | } else if (!cdev_get(p)) | |
392 | ret = -ENXIO; | |
393 | } else if (!cdev_get(p)) | |
394 | ret = -ENXIO; | |
395 | spin_unlock(&cdev_lock); | |
396 | cdev_put(new); | |
397 | if (ret) | |
398 | return ret; | |
a518ab93 CH |
399 | |
400 | ret = -ENXIO; | |
e84f9e57 AV |
401 | fops = fops_get(p->ops); |
402 | if (!fops) | |
a518ab93 CH |
403 | goto out_cdev_put; |
404 | ||
e84f9e57 | 405 | replace_fops(filp, fops); |
a518ab93 | 406 | if (filp->f_op->open) { |
1ff97647 | 407 | ret = filp->f_op->open(inode, filp); |
a518ab93 CH |
408 | if (ret) |
409 | goto out_cdev_put; | |
410 | } | |
411 | ||
412 | return 0; | |
413 | ||
414 | out_cdev_put: | |
415 | cdev_put(p); | |
1da177e4 LT |
416 | return ret; |
417 | } | |
418 | ||
419 | void cd_forget(struct inode *inode) | |
420 | { | |
421 | spin_lock(&cdev_lock); | |
422 | list_del_init(&inode->i_devices); | |
423 | inode->i_cdev = NULL; | |
3bc52c45 | 424 | inode->i_mapping = &inode->i_data; |
1da177e4 LT |
425 | spin_unlock(&cdev_lock); |
426 | } | |
427 | ||
75c96f85 | 428 | static void cdev_purge(struct cdev *cdev) |
1da177e4 LT |
429 | { |
430 | spin_lock(&cdev_lock); | |
431 | while (!list_empty(&cdev->list)) { | |
432 | struct inode *inode; | |
433 | inode = container_of(cdev->list.next, struct inode, i_devices); | |
434 | list_del_init(&inode->i_devices); | |
435 | inode->i_cdev = NULL; | |
436 | } | |
437 | spin_unlock(&cdev_lock); | |
438 | } | |
439 | ||
440 | /* | |
441 | * Dummy default file-operations: the only thing this does | |
442 | * is contain the open that then fills in the correct operations | |
443 | * depending on the special file... | |
444 | */ | |
4b6f5d20 | 445 | const struct file_operations def_chr_fops = { |
1da177e4 | 446 | .open = chrdev_open, |
6038f373 | 447 | .llseek = noop_llseek, |
1da177e4 LT |
448 | }; |
449 | ||
450 | static struct kobject *exact_match(dev_t dev, int *part, void *data) | |
451 | { | |
452 | struct cdev *p = data; | |
453 | return &p->kobj; | |
454 | } | |
455 | ||
456 | static int exact_lock(dev_t dev, void *data) | |
457 | { | |
458 | struct cdev *p = data; | |
459 | return cdev_get(p) ? 0 : -1; | |
460 | } | |
461 | ||
cf3e43db JC |
462 | /** |
463 | * cdev_add() - add a char device to the system | |
464 | * @p: the cdev structure for the device | |
465 | * @dev: the first device number for which this device is responsible | |
466 | * @count: the number of consecutive minor numbers corresponding to this | |
467 | * device | |
468 | * | |
469 | * cdev_add() adds the device represented by @p to the system, making it | |
470 | * live immediately. A negative error code is returned on failure. | |
471 | */ | |
1da177e4 LT |
472 | int cdev_add(struct cdev *p, dev_t dev, unsigned count) |
473 | { | |
2f0157f1 DT |
474 | int error; |
475 | ||
1da177e4 LT |
476 | p->dev = dev; |
477 | p->count = count; | |
2f0157f1 DT |
478 | |
479 | error = kobj_map(cdev_map, dev, count, NULL, | |
480 | exact_match, exact_lock, p); | |
481 | if (error) | |
482 | return error; | |
483 | ||
484 | kobject_get(p->kobj.parent); | |
485 | ||
486 | return 0; | |
1da177e4 LT |
487 | } |
488 | ||
233ed09d LG |
489 | /** |
490 | * cdev_set_parent() - set the parent kobject for a char device | |
491 | * @p: the cdev structure | |
492 | * @kobj: the kobject to take a reference to | |
493 | * | |
494 | * cdev_set_parent() sets a parent kobject which will be referenced | |
495 | * appropriately so the parent is not freed before the cdev. This | |
496 | * should be called before cdev_add. | |
497 | */ | |
498 | void cdev_set_parent(struct cdev *p, struct kobject *kobj) | |
499 | { | |
500 | WARN_ON(!kobj->state_initialized); | |
501 | p->kobj.parent = kobj; | |
502 | } | |
503 | ||
504 | /** | |
505 | * cdev_device_add() - add a char device and it's corresponding | |
506 | * struct device, linkink | |
507 | * @dev: the device structure | |
508 | * @cdev: the cdev structure | |
509 | * | |
510 | * cdev_device_add() adds the char device represented by @cdev to the system, | |
511 | * just as cdev_add does. It then adds @dev to the system using device_add | |
512 | * The dev_t for the char device will be taken from the struct device which | |
513 | * needs to be initialized first. This helper function correctly takes a | |
514 | * reference to the parent device so the parent will not get released until | |
515 | * all references to the cdev are released. | |
516 | * | |
517 | * This helper uses dev->devt for the device number. If it is not set | |
518 | * it will not add the cdev and it will be equivalent to device_add. | |
519 | * | |
520 | * This function should be used whenever the struct cdev and the | |
521 | * struct device are members of the same structure whose lifetime is | |
522 | * managed by the struct device. | |
523 | * | |
524 | * NOTE: Callers must assume that userspace was able to open the cdev and | |
525 | * can call cdev fops callbacks at any time, even if this function fails. | |
526 | */ | |
527 | int cdev_device_add(struct cdev *cdev, struct device *dev) | |
528 | { | |
529 | int rc = 0; | |
530 | ||
531 | if (dev->devt) { | |
532 | cdev_set_parent(cdev, &dev->kobj); | |
533 | ||
534 | rc = cdev_add(cdev, dev->devt, 1); | |
535 | if (rc) | |
536 | return rc; | |
537 | } | |
538 | ||
539 | rc = device_add(dev); | |
540 | if (rc) | |
541 | cdev_del(cdev); | |
542 | ||
543 | return rc; | |
544 | } | |
545 | ||
546 | /** | |
547 | * cdev_device_del() - inverse of cdev_device_add | |
548 | * @dev: the device structure | |
549 | * @cdev: the cdev structure | |
550 | * | |
551 | * cdev_device_del() is a helper function to call cdev_del and device_del. | |
552 | * It should be used whenever cdev_device_add is used. | |
553 | * | |
554 | * If dev->devt is not set it will not remove the cdev and will be equivalent | |
555 | * to device_del. | |
556 | * | |
557 | * NOTE: This guarantees that associated sysfs callbacks are not running | |
558 | * or runnable, however any cdevs already open will remain and their fops | |
559 | * will still be callable even after this function returns. | |
560 | */ | |
561 | void cdev_device_del(struct cdev *cdev, struct device *dev) | |
562 | { | |
563 | device_del(dev); | |
564 | if (dev->devt) | |
565 | cdev_del(cdev); | |
566 | } | |
567 | ||
1da177e4 LT |
568 | static void cdev_unmap(dev_t dev, unsigned count) |
569 | { | |
570 | kobj_unmap(cdev_map, dev, count); | |
571 | } | |
572 | ||
cf3e43db JC |
573 | /** |
574 | * cdev_del() - remove a cdev from the system | |
575 | * @p: the cdev structure to be removed | |
576 | * | |
577 | * cdev_del() removes @p from the system, possibly freeing the structure | |
578 | * itself. | |
233ed09d LG |
579 | * |
580 | * NOTE: This guarantees that cdev device will no longer be able to be | |
581 | * opened, however any cdevs already open will remain and their fops will | |
582 | * still be callable even after cdev_del returns. | |
cf3e43db | 583 | */ |
1da177e4 LT |
584 | void cdev_del(struct cdev *p) |
585 | { | |
586 | cdev_unmap(p->dev, p->count); | |
587 | kobject_put(&p->kobj); | |
588 | } | |
589 | ||
590 | ||
591 | static void cdev_default_release(struct kobject *kobj) | |
592 | { | |
593 | struct cdev *p = container_of(kobj, struct cdev, kobj); | |
2f0157f1 DT |
594 | struct kobject *parent = kobj->parent; |
595 | ||
1da177e4 | 596 | cdev_purge(p); |
2f0157f1 | 597 | kobject_put(parent); |
1da177e4 LT |
598 | } |
599 | ||
600 | static void cdev_dynamic_release(struct kobject *kobj) | |
601 | { | |
602 | struct cdev *p = container_of(kobj, struct cdev, kobj); | |
2f0157f1 DT |
603 | struct kobject *parent = kobj->parent; |
604 | ||
1da177e4 LT |
605 | cdev_purge(p); |
606 | kfree(p); | |
2f0157f1 | 607 | kobject_put(parent); |
1da177e4 LT |
608 | } |
609 | ||
610 | static struct kobj_type ktype_cdev_default = { | |
611 | .release = cdev_default_release, | |
612 | }; | |
613 | ||
614 | static struct kobj_type ktype_cdev_dynamic = { | |
615 | .release = cdev_dynamic_release, | |
616 | }; | |
617 | ||
cf3e43db JC |
618 | /** |
619 | * cdev_alloc() - allocate a cdev structure | |
620 | * | |
621 | * Allocates and returns a cdev structure, or NULL on failure. | |
622 | */ | |
1da177e4 LT |
623 | struct cdev *cdev_alloc(void) |
624 | { | |
11b0b5ab | 625 | struct cdev *p = kzalloc(sizeof(struct cdev), GFP_KERNEL); |
1da177e4 | 626 | if (p) { |
1da177e4 | 627 | INIT_LIST_HEAD(&p->list); |
f9cb074b | 628 | kobject_init(&p->kobj, &ktype_cdev_dynamic); |
1da177e4 LT |
629 | } |
630 | return p; | |
631 | } | |
632 | ||
cf3e43db JC |
633 | /** |
634 | * cdev_init() - initialize a cdev structure | |
635 | * @cdev: the structure to initialize | |
636 | * @fops: the file_operations for this device | |
637 | * | |
638 | * Initializes @cdev, remembering @fops, making it ready to add to the | |
639 | * system with cdev_add(). | |
640 | */ | |
99ac48f5 | 641 | void cdev_init(struct cdev *cdev, const struct file_operations *fops) |
1da177e4 LT |
642 | { |
643 | memset(cdev, 0, sizeof *cdev); | |
644 | INIT_LIST_HEAD(&cdev->list); | |
f9cb074b | 645 | kobject_init(&cdev->kobj, &ktype_cdev_default); |
1da177e4 LT |
646 | cdev->ops = fops; |
647 | } | |
648 | ||
649 | static struct kobject *base_probe(dev_t dev, int *part, void *data) | |
650 | { | |
651 | if (request_module("char-major-%d-%d", MAJOR(dev), MINOR(dev)) > 0) | |
652 | /* Make old-style 2.4 aliases work */ | |
653 | request_module("char-major-%d", MAJOR(dev)); | |
654 | return NULL; | |
655 | } | |
656 | ||
657 | void __init chrdev_init(void) | |
658 | { | |
659 | cdev_map = kobj_map_init(base_probe, &chrdevs_lock); | |
660 | } | |
661 | ||
662 | ||
663 | /* Let modules do char dev stuff */ | |
664 | EXPORT_SYMBOL(register_chrdev_region); | |
665 | EXPORT_SYMBOL(unregister_chrdev_region); | |
666 | EXPORT_SYMBOL(alloc_chrdev_region); | |
667 | EXPORT_SYMBOL(cdev_init); | |
668 | EXPORT_SYMBOL(cdev_alloc); | |
669 | EXPORT_SYMBOL(cdev_del); | |
670 | EXPORT_SYMBOL(cdev_add); | |
233ed09d LG |
671 | EXPORT_SYMBOL(cdev_set_parent); |
672 | EXPORT_SYMBOL(cdev_device_add); | |
673 | EXPORT_SYMBOL(cdev_device_del); | |
1905b1bf TH |
674 | EXPORT_SYMBOL(__register_chrdev); |
675 | EXPORT_SYMBOL(__unregister_chrdev); |