Commit | Line | Data |
---|---|---|
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 | 30 | |
8a932f73 LG |
31 | #define CHRDEV_MAJOR_HASH_SIZE 255 |
32 | ||
1da177e4 LT |
33 | static struct char_device_struct { |
34 | struct char_device_struct *next; | |
35 | unsigned int major; | |
36 | unsigned int baseminor; | |
37 | int minorct; | |
7170be5f | 38 | char name[64]; |
1da177e4 | 39 | struct cdev *cdev; /* will die */ |
68eef3b4 | 40 | } *chrdevs[CHRDEV_MAJOR_HASH_SIZE]; |
1da177e4 LT |
41 | |
42 | /* index in the above */ | |
e61eb2e9 | 43 | static inline int major_to_index(unsigned major) |
1da177e4 | 44 | { |
68eef3b4 | 45 | return major % CHRDEV_MAJOR_HASH_SIZE; |
7170be5f NH |
46 | } |
47 | ||
68eef3b4 | 48 | #ifdef CONFIG_PROC_FS |
7170be5f | 49 | |
68eef3b4 | 50 | void chrdev_show(struct seq_file *f, off_t offset) |
7170be5f NH |
51 | { |
52 | struct char_device_struct *cd; | |
7170be5f | 53 | |
8a932f73 LG |
54 | mutex_lock(&chrdevs_lock); |
55 | for (cd = chrdevs[major_to_index(offset)]; cd; cd = cd->next) { | |
56 | if (cd->major == offset) | |
68eef3b4 | 57 | seq_printf(f, "%3d %s\n", cd->major, cd->name); |
1da177e4 | 58 | } |
8a932f73 | 59 | mutex_unlock(&chrdevs_lock); |
7170be5f NH |
60 | } |
61 | ||
68eef3b4 | 62 | #endif /* CONFIG_PROC_FS */ |
1da177e4 | 63 | |
a5d31a3f LG |
64 | static int find_dynamic_major(void) |
65 | { | |
66 | int i; | |
67 | struct char_device_struct *cd; | |
68 | ||
69 | for (i = ARRAY_SIZE(chrdevs)-1; i > CHRDEV_MAJOR_DYN_END; i--) { | |
70 | if (chrdevs[i] == NULL) | |
71 | return i; | |
72 | } | |
73 | ||
74 | for (i = CHRDEV_MAJOR_DYN_EXT_START; | |
75 | i > CHRDEV_MAJOR_DYN_EXT_END; i--) { | |
76 | for (cd = chrdevs[major_to_index(i)]; cd; cd = cd->next) | |
77 | if (cd->major == i) | |
78 | break; | |
79 | ||
80 | if (cd == NULL || cd->major != i) | |
81 | return i; | |
82 | } | |
83 | ||
84 | return -EBUSY; | |
85 | } | |
86 | ||
1da177e4 LT |
87 | /* |
88 | * Register a single major with a specified minor range. | |
89 | * | |
90 | * If major == 0 this functions will dynamically allocate a major and return | |
91 | * its number. | |
92 | * | |
93 | * If major > 0 this function will attempt to reserve the passed range of | |
94 | * minors and will return zero on success. | |
95 | * | |
96 | * Returns a -ve errno on failure. | |
97 | */ | |
98 | static struct char_device_struct * | |
99 | __register_chrdev_region(unsigned int major, unsigned int baseminor, | |
100 | int minorct, const char *name) | |
101 | { | |
102 | struct char_device_struct *cd, **cp; | |
103 | int ret = 0; | |
104 | int i; | |
105 | ||
11b0b5ab | 106 | cd = kzalloc(sizeof(struct char_device_struct), GFP_KERNEL); |
1da177e4 LT |
107 | if (cd == NULL) |
108 | return ERR_PTR(-ENOMEM); | |
109 | ||
58383af6 | 110 | mutex_lock(&chrdevs_lock); |
1da177e4 | 111 | |
1da177e4 | 112 | if (major == 0) { |
a5d31a3f LG |
113 | ret = find_dynamic_major(); |
114 | if (ret < 0) { | |
115 | pr_err("CHRDEV \"%s\" dynamic allocation region is full\n", | |
116 | name); | |
1da177e4 LT |
117 | goto out; |
118 | } | |
a5d31a3f | 119 | major = ret; |
1da177e4 LT |
120 | } |
121 | ||
8a932f73 LG |
122 | if (major >= CHRDEV_MAJOR_MAX) { |
123 | pr_err("CHRDEV \"%s\" major requested (%d) is greater than the maximum (%d)\n", | |
124 | name, major, CHRDEV_MAJOR_MAX); | |
125 | ret = -EINVAL; | |
126 | goto out; | |
127 | } | |
128 | ||
1da177e4 LT |
129 | cd->major = major; |
130 | cd->baseminor = baseminor; | |
131 | cd->minorct = minorct; | |
8c401888 | 132 | strlcpy(cd->name, name, sizeof(cd->name)); |
1da177e4 LT |
133 | |
134 | i = major_to_index(major); | |
135 | ||
136 | for (cp = &chrdevs[i]; *cp; cp = &(*cp)->next) | |
137 | if ((*cp)->major > major || | |
01d553d0 AW |
138 | ((*cp)->major == major && |
139 | (((*cp)->baseminor >= baseminor) || | |
140 | ((*cp)->baseminor + (*cp)->minorct > baseminor)))) | |
1da177e4 | 141 | break; |
01d553d0 AW |
142 | |
143 | /* Check for overlapping minor ranges. */ | |
144 | if (*cp && (*cp)->major == major) { | |
145 | int old_min = (*cp)->baseminor; | |
146 | int old_max = (*cp)->baseminor + (*cp)->minorct - 1; | |
147 | int new_min = baseminor; | |
148 | int new_max = baseminor + minorct - 1; | |
149 | ||
150 | /* New driver overlaps from the left. */ | |
151 | if (new_max >= old_min && new_max <= old_max) { | |
152 | ret = -EBUSY; | |
153 | goto out; | |
154 | } | |
155 | ||
156 | /* New driver overlaps from the right. */ | |
157 | if (new_min <= old_max && new_min >= old_min) { | |
158 | ret = -EBUSY; | |
159 | goto out; | |
160 | } | |
1da177e4 | 161 | } |
01d553d0 | 162 | |
1da177e4 LT |
163 | cd->next = *cp; |
164 | *cp = cd; | |
58383af6 | 165 | mutex_unlock(&chrdevs_lock); |
1da177e4 LT |
166 | return cd; |
167 | out: | |
58383af6 | 168 | mutex_unlock(&chrdevs_lock); |
1da177e4 LT |
169 | kfree(cd); |
170 | return ERR_PTR(ret); | |
171 | } | |
172 | ||
173 | static struct char_device_struct * | |
174 | __unregister_chrdev_region(unsigned major, unsigned baseminor, int minorct) | |
175 | { | |
176 | struct char_device_struct *cd = NULL, **cp; | |
177 | int i = major_to_index(major); | |
178 | ||
58383af6 | 179 | mutex_lock(&chrdevs_lock); |
1da177e4 LT |
180 | for (cp = &chrdevs[i]; *cp; cp = &(*cp)->next) |
181 | if ((*cp)->major == major && | |
182 | (*cp)->baseminor == baseminor && | |
183 | (*cp)->minorct == minorct) | |
184 | break; | |
185 | if (*cp) { | |
186 | cd = *cp; | |
187 | *cp = cd->next; | |
188 | } | |
58383af6 | 189 | mutex_unlock(&chrdevs_lock); |
1da177e4 LT |
190 | return cd; |
191 | } | |
192 | ||
cf3e43db JC |
193 | /** |
194 | * register_chrdev_region() - register a range of device numbers | |
195 | * @from: the first in the desired range of device numbers; must include | |
196 | * the major number. | |
197 | * @count: the number of consecutive device numbers required | |
198 | * @name: the name of the device or driver. | |
199 | * | |
200 | * Return value is zero on success, a negative error code on failure. | |
201 | */ | |
1da177e4 LT |
202 | int register_chrdev_region(dev_t from, unsigned count, const char *name) |
203 | { | |
204 | struct char_device_struct *cd; | |
205 | dev_t to = from + count; | |
206 | dev_t n, next; | |
207 | ||
208 | for (n = from; n < to; n = next) { | |
209 | next = MKDEV(MAJOR(n)+1, 0); | |
210 | if (next > to) | |
211 | next = to; | |
212 | cd = __register_chrdev_region(MAJOR(n), MINOR(n), | |
213 | next - n, name); | |
214 | if (IS_ERR(cd)) | |
215 | goto fail; | |
216 | } | |
217 | return 0; | |
218 | fail: | |
219 | to = n; | |
220 | for (n = from; n < to; n = next) { | |
221 | next = MKDEV(MAJOR(n)+1, 0); | |
222 | kfree(__unregister_chrdev_region(MAJOR(n), MINOR(n), next - n)); | |
223 | } | |
224 | return PTR_ERR(cd); | |
225 | } | |
226 | ||
cf3e43db JC |
227 | /** |
228 | * alloc_chrdev_region() - register a range of char device numbers | |
229 | * @dev: output parameter for first assigned number | |
230 | * @baseminor: first of the requested range of minor numbers | |
231 | * @count: the number of minor numbers required | |
232 | * @name: the name of the associated device or driver | |
233 | * | |
234 | * Allocates a range of char device numbers. The major number will be | |
235 | * chosen dynamically, and returned (along with the first minor number) | |
236 | * in @dev. Returns zero or a negative error code. | |
237 | */ | |
1da177e4 LT |
238 | int alloc_chrdev_region(dev_t *dev, unsigned baseminor, unsigned count, |
239 | const char *name) | |
240 | { | |
241 | struct char_device_struct *cd; | |
242 | cd = __register_chrdev_region(0, baseminor, count, name); | |
243 | if (IS_ERR(cd)) | |
244 | return PTR_ERR(cd); | |
245 | *dev = MKDEV(cd->major, cd->baseminor); | |
246 | return 0; | |
247 | } | |
248 | ||
d247e2c6 | 249 | /** |
1905b1bf | 250 | * __register_chrdev() - create and register a cdev occupying a range of minors |
d247e2c6 | 251 | * @major: major device number or 0 for dynamic allocation |
1905b1bf TH |
252 | * @baseminor: first of the requested range of minor numbers |
253 | * @count: the number of minor numbers required | |
d247e2c6 REB |
254 | * @name: name of this range of devices |
255 | * @fops: file operations associated with this devices | |
256 | * | |
257 | * If @major == 0 this functions will dynamically allocate a major and return | |
258 | * its number. | |
259 | * | |
260 | * If @major > 0 this function will attempt to reserve a device with the given | |
261 | * major number and will return zero on success. | |
262 | * | |
263 | * Returns a -ve errno on failure. | |
264 | * | |
265 | * The name of this device has nothing to do with the name of the device in | |
266 | * /dev. It only helps to keep track of the different owners of devices. If | |
267 | * your module name has only one type of devices it's ok to use e.g. the name | |
268 | * of the module here. | |
d247e2c6 | 269 | */ |
1905b1bf TH |
270 | int __register_chrdev(unsigned int major, unsigned int baseminor, |
271 | unsigned int count, const char *name, | |
272 | const struct file_operations *fops) | |
1da177e4 LT |
273 | { |
274 | struct char_device_struct *cd; | |
275 | struct cdev *cdev; | |
1da177e4 LT |
276 | int err = -ENOMEM; |
277 | ||
1905b1bf | 278 | cd = __register_chrdev_region(major, baseminor, count, name); |
1da177e4 LT |
279 | if (IS_ERR(cd)) |
280 | return PTR_ERR(cd); | |
1ff97647 | 281 | |
1da177e4 LT |
282 | cdev = cdev_alloc(); |
283 | if (!cdev) | |
284 | goto out2; | |
285 | ||
286 | cdev->owner = fops->owner; | |
287 | cdev->ops = fops; | |
288 | kobject_set_name(&cdev->kobj, "%s", name); | |
1ff97647 | 289 | |
1905b1bf | 290 | err = cdev_add(cdev, MKDEV(cd->major, baseminor), count); |
1da177e4 LT |
291 | if (err) |
292 | goto out; | |
293 | ||
294 | cd->cdev = cdev; | |
295 | ||
296 | return major ? 0 : cd->major; | |
297 | out: | |
298 | kobject_put(&cdev->kobj); | |
299 | out2: | |
1905b1bf | 300 | kfree(__unregister_chrdev_region(cd->major, baseminor, count)); |
1da177e4 LT |
301 | return err; |
302 | } | |
303 | ||
cf3e43db | 304 | /** |
594069bc | 305 | * unregister_chrdev_region() - unregister a range of device numbers |
cf3e43db JC |
306 | * @from: the first in the range of numbers to unregister |
307 | * @count: the number of device numbers to unregister | |
308 | * | |
309 | * This function will unregister a range of @count device numbers, | |
310 | * starting with @from. The caller should normally be the one who | |
311 | * allocated those numbers in the first place... | |
312 | */ | |
1da177e4 LT |
313 | void unregister_chrdev_region(dev_t from, unsigned count) |
314 | { | |
315 | dev_t to = from + count; | |
316 | dev_t n, next; | |
317 | ||
318 | for (n = from; n < to; n = next) { | |
319 | next = MKDEV(MAJOR(n)+1, 0); | |
320 | if (next > to) | |
321 | next = to; | |
322 | kfree(__unregister_chrdev_region(MAJOR(n), MINOR(n), next - n)); | |
323 | } | |
324 | } | |
325 | ||
1905b1bf TH |
326 | /** |
327 | * __unregister_chrdev - unregister and destroy a cdev | |
328 | * @major: major device number | |
329 | * @baseminor: first of the range of minor numbers | |
330 | * @count: the number of minor numbers this cdev is occupying | |
331 | * @name: name of this range of devices | |
332 | * | |
333 | * Unregister and destroy the cdev occupying the region described by | |
334 | * @major, @baseminor and @count. This function undoes what | |
335 | * __register_chrdev() did. | |
336 | */ | |
337 | void __unregister_chrdev(unsigned int major, unsigned int baseminor, | |
338 | unsigned int count, const char *name) | |
1da177e4 LT |
339 | { |
340 | struct char_device_struct *cd; | |
1905b1bf TH |
341 | |
342 | cd = __unregister_chrdev_region(major, baseminor, count); | |
1da177e4 LT |
343 | if (cd && cd->cdev) |
344 | cdev_del(cd->cdev); | |
345 | kfree(cd); | |
1da177e4 LT |
346 | } |
347 | ||
348 | static DEFINE_SPINLOCK(cdev_lock); | |
349 | ||
350 | static struct kobject *cdev_get(struct cdev *p) | |
351 | { | |
352 | struct module *owner = p->owner; | |
353 | struct kobject *kobj; | |
354 | ||
355 | if (owner && !try_module_get(owner)) | |
356 | return NULL; | |
357 | kobj = kobject_get(&p->kobj); | |
358 | if (!kobj) | |
359 | module_put(owner); | |
360 | return kobj; | |
361 | } | |
362 | ||
363 | void cdev_put(struct cdev *p) | |
364 | { | |
365 | if (p) { | |
7da6844c | 366 | struct module *owner = p->owner; |
1da177e4 | 367 | kobject_put(&p->kobj); |
7da6844c | 368 | module_put(owner); |
1da177e4 LT |
369 | } |
370 | } | |
371 | ||
372 | /* | |
373 | * Called every time a character special file is opened | |
374 | */ | |
922f9cfa | 375 | static int chrdev_open(struct inode *inode, struct file *filp) |
1da177e4 | 376 | { |
e84f9e57 | 377 | const struct file_operations *fops; |
1da177e4 LT |
378 | struct cdev *p; |
379 | struct cdev *new = NULL; | |
380 | int ret = 0; | |
381 | ||
382 | spin_lock(&cdev_lock); | |
383 | p = inode->i_cdev; | |
384 | if (!p) { | |
385 | struct kobject *kobj; | |
386 | int idx; | |
387 | spin_unlock(&cdev_lock); | |
388 | kobj = kobj_lookup(cdev_map, inode->i_rdev, &idx); | |
389 | if (!kobj) | |
390 | return -ENXIO; | |
391 | new = container_of(kobj, struct cdev, kobj); | |
392 | spin_lock(&cdev_lock); | |
a30427d9 JC |
393 | /* Check i_cdev again in case somebody beat us to it while |
394 | we dropped the lock. */ | |
1da177e4 LT |
395 | p = inode->i_cdev; |
396 | if (!p) { | |
397 | inode->i_cdev = p = new; | |
1da177e4 LT |
398 | list_add(&inode->i_devices, &p->list); |
399 | new = NULL; | |
400 | } else if (!cdev_get(p)) | |
401 | ret = -ENXIO; | |
402 | } else if (!cdev_get(p)) | |
403 | ret = -ENXIO; | |
404 | spin_unlock(&cdev_lock); | |
405 | cdev_put(new); | |
406 | if (ret) | |
407 | return ret; | |
a518ab93 CH |
408 | |
409 | ret = -ENXIO; | |
e84f9e57 AV |
410 | fops = fops_get(p->ops); |
411 | if (!fops) | |
a518ab93 CH |
412 | goto out_cdev_put; |
413 | ||
e84f9e57 | 414 | replace_fops(filp, fops); |
a518ab93 | 415 | if (filp->f_op->open) { |
1ff97647 | 416 | ret = filp->f_op->open(inode, filp); |
a518ab93 CH |
417 | if (ret) |
418 | goto out_cdev_put; | |
419 | } | |
420 | ||
421 | return 0; | |
422 | ||
423 | out_cdev_put: | |
424 | cdev_put(p); | |
1da177e4 LT |
425 | return ret; |
426 | } | |
427 | ||
428 | void cd_forget(struct inode *inode) | |
429 | { | |
430 | spin_lock(&cdev_lock); | |
431 | list_del_init(&inode->i_devices); | |
432 | inode->i_cdev = NULL; | |
3bc52c45 | 433 | inode->i_mapping = &inode->i_data; |
1da177e4 LT |
434 | spin_unlock(&cdev_lock); |
435 | } | |
436 | ||
75c96f85 | 437 | static void cdev_purge(struct cdev *cdev) |
1da177e4 LT |
438 | { |
439 | spin_lock(&cdev_lock); | |
440 | while (!list_empty(&cdev->list)) { | |
441 | struct inode *inode; | |
442 | inode = container_of(cdev->list.next, struct inode, i_devices); | |
443 | list_del_init(&inode->i_devices); | |
444 | inode->i_cdev = NULL; | |
445 | } | |
446 | spin_unlock(&cdev_lock); | |
447 | } | |
448 | ||
449 | /* | |
450 | * Dummy default file-operations: the only thing this does | |
451 | * is contain the open that then fills in the correct operations | |
452 | * depending on the special file... | |
453 | */ | |
4b6f5d20 | 454 | const struct file_operations def_chr_fops = { |
1da177e4 | 455 | .open = chrdev_open, |
6038f373 | 456 | .llseek = noop_llseek, |
1da177e4 LT |
457 | }; |
458 | ||
459 | static struct kobject *exact_match(dev_t dev, int *part, void *data) | |
460 | { | |
461 | struct cdev *p = data; | |
462 | return &p->kobj; | |
463 | } | |
464 | ||
465 | static int exact_lock(dev_t dev, void *data) | |
466 | { | |
467 | struct cdev *p = data; | |
468 | return cdev_get(p) ? 0 : -1; | |
469 | } | |
470 | ||
cf3e43db JC |
471 | /** |
472 | * cdev_add() - add a char device to the system | |
473 | * @p: the cdev structure for the device | |
474 | * @dev: the first device number for which this device is responsible | |
475 | * @count: the number of consecutive minor numbers corresponding to this | |
476 | * device | |
477 | * | |
478 | * cdev_add() adds the device represented by @p to the system, making it | |
479 | * live immediately. A negative error code is returned on failure. | |
480 | */ | |
1da177e4 LT |
481 | int cdev_add(struct cdev *p, dev_t dev, unsigned count) |
482 | { | |
2f0157f1 DT |
483 | int error; |
484 | ||
1da177e4 LT |
485 | p->dev = dev; |
486 | p->count = count; | |
2f0157f1 DT |
487 | |
488 | error = kobj_map(cdev_map, dev, count, NULL, | |
489 | exact_match, exact_lock, p); | |
490 | if (error) | |
491 | return error; | |
492 | ||
493 | kobject_get(p->kobj.parent); | |
494 | ||
495 | return 0; | |
1da177e4 LT |
496 | } |
497 | ||
233ed09d LG |
498 | /** |
499 | * cdev_set_parent() - set the parent kobject for a char device | |
500 | * @p: the cdev structure | |
501 | * @kobj: the kobject to take a reference to | |
502 | * | |
503 | * cdev_set_parent() sets a parent kobject which will be referenced | |
504 | * appropriately so the parent is not freed before the cdev. This | |
505 | * should be called before cdev_add. | |
506 | */ | |
507 | void cdev_set_parent(struct cdev *p, struct kobject *kobj) | |
508 | { | |
509 | WARN_ON(!kobj->state_initialized); | |
510 | p->kobj.parent = kobj; | |
511 | } | |
512 | ||
513 | /** | |
514 | * cdev_device_add() - add a char device and it's corresponding | |
515 | * struct device, linkink | |
516 | * @dev: the device structure | |
517 | * @cdev: the cdev structure | |
518 | * | |
519 | * cdev_device_add() adds the char device represented by @cdev to the system, | |
520 | * just as cdev_add does. It then adds @dev to the system using device_add | |
521 | * The dev_t for the char device will be taken from the struct device which | |
522 | * needs to be initialized first. This helper function correctly takes a | |
523 | * reference to the parent device so the parent will not get released until | |
524 | * all references to the cdev are released. | |
525 | * | |
526 | * This helper uses dev->devt for the device number. If it is not set | |
527 | * it will not add the cdev and it will be equivalent to device_add. | |
528 | * | |
529 | * This function should be used whenever the struct cdev and the | |
530 | * struct device are members of the same structure whose lifetime is | |
531 | * managed by the struct device. | |
532 | * | |
533 | * NOTE: Callers must assume that userspace was able to open the cdev and | |
534 | * can call cdev fops callbacks at any time, even if this function fails. | |
535 | */ | |
536 | int cdev_device_add(struct cdev *cdev, struct device *dev) | |
537 | { | |
538 | int rc = 0; | |
539 | ||
540 | if (dev->devt) { | |
541 | cdev_set_parent(cdev, &dev->kobj); | |
542 | ||
543 | rc = cdev_add(cdev, dev->devt, 1); | |
544 | if (rc) | |
545 | return rc; | |
546 | } | |
547 | ||
548 | rc = device_add(dev); | |
549 | if (rc) | |
550 | cdev_del(cdev); | |
551 | ||
552 | return rc; | |
553 | } | |
554 | ||
555 | /** | |
556 | * cdev_device_del() - inverse of cdev_device_add | |
557 | * @dev: the device structure | |
558 | * @cdev: the cdev structure | |
559 | * | |
560 | * cdev_device_del() is a helper function to call cdev_del and device_del. | |
561 | * It should be used whenever cdev_device_add is used. | |
562 | * | |
563 | * If dev->devt is not set it will not remove the cdev and will be equivalent | |
564 | * to device_del. | |
565 | * | |
566 | * NOTE: This guarantees that associated sysfs callbacks are not running | |
567 | * or runnable, however any cdevs already open will remain and their fops | |
568 | * will still be callable even after this function returns. | |
569 | */ | |
570 | void cdev_device_del(struct cdev *cdev, struct device *dev) | |
571 | { | |
572 | device_del(dev); | |
573 | if (dev->devt) | |
574 | cdev_del(cdev); | |
575 | } | |
576 | ||
1da177e4 LT |
577 | static void cdev_unmap(dev_t dev, unsigned count) |
578 | { | |
579 | kobj_unmap(cdev_map, dev, count); | |
580 | } | |
581 | ||
cf3e43db JC |
582 | /** |
583 | * cdev_del() - remove a cdev from the system | |
584 | * @p: the cdev structure to be removed | |
585 | * | |
586 | * cdev_del() removes @p from the system, possibly freeing the structure | |
587 | * itself. | |
233ed09d LG |
588 | * |
589 | * NOTE: This guarantees that cdev device will no longer be able to be | |
590 | * opened, however any cdevs already open will remain and their fops will | |
591 | * still be callable even after cdev_del returns. | |
cf3e43db | 592 | */ |
1da177e4 LT |
593 | void cdev_del(struct cdev *p) |
594 | { | |
595 | cdev_unmap(p->dev, p->count); | |
596 | kobject_put(&p->kobj); | |
597 | } | |
598 | ||
599 | ||
600 | static void cdev_default_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 | 605 | cdev_purge(p); |
2f0157f1 | 606 | kobject_put(parent); |
1da177e4 LT |
607 | } |
608 | ||
609 | static void cdev_dynamic_release(struct kobject *kobj) | |
610 | { | |
611 | struct cdev *p = container_of(kobj, struct cdev, kobj); | |
2f0157f1 DT |
612 | struct kobject *parent = kobj->parent; |
613 | ||
1da177e4 LT |
614 | cdev_purge(p); |
615 | kfree(p); | |
2f0157f1 | 616 | kobject_put(parent); |
1da177e4 LT |
617 | } |
618 | ||
619 | static struct kobj_type ktype_cdev_default = { | |
620 | .release = cdev_default_release, | |
621 | }; | |
622 | ||
623 | static struct kobj_type ktype_cdev_dynamic = { | |
624 | .release = cdev_dynamic_release, | |
625 | }; | |
626 | ||
cf3e43db JC |
627 | /** |
628 | * cdev_alloc() - allocate a cdev structure | |
629 | * | |
630 | * Allocates and returns a cdev structure, or NULL on failure. | |
631 | */ | |
1da177e4 LT |
632 | struct cdev *cdev_alloc(void) |
633 | { | |
11b0b5ab | 634 | struct cdev *p = kzalloc(sizeof(struct cdev), GFP_KERNEL); |
1da177e4 | 635 | if (p) { |
1da177e4 | 636 | INIT_LIST_HEAD(&p->list); |
f9cb074b | 637 | kobject_init(&p->kobj, &ktype_cdev_dynamic); |
1da177e4 LT |
638 | } |
639 | return p; | |
640 | } | |
641 | ||
cf3e43db JC |
642 | /** |
643 | * cdev_init() - initialize a cdev structure | |
644 | * @cdev: the structure to initialize | |
645 | * @fops: the file_operations for this device | |
646 | * | |
647 | * Initializes @cdev, remembering @fops, making it ready to add to the | |
648 | * system with cdev_add(). | |
649 | */ | |
99ac48f5 | 650 | void cdev_init(struct cdev *cdev, const struct file_operations *fops) |
1da177e4 LT |
651 | { |
652 | memset(cdev, 0, sizeof *cdev); | |
653 | INIT_LIST_HEAD(&cdev->list); | |
f9cb074b | 654 | kobject_init(&cdev->kobj, &ktype_cdev_default); |
1da177e4 LT |
655 | cdev->ops = fops; |
656 | } | |
657 | ||
658 | static struct kobject *base_probe(dev_t dev, int *part, void *data) | |
659 | { | |
660 | if (request_module("char-major-%d-%d", MAJOR(dev), MINOR(dev)) > 0) | |
661 | /* Make old-style 2.4 aliases work */ | |
662 | request_module("char-major-%d", MAJOR(dev)); | |
663 | return NULL; | |
664 | } | |
665 | ||
666 | void __init chrdev_init(void) | |
667 | { | |
668 | cdev_map = kobj_map_init(base_probe, &chrdevs_lock); | |
669 | } | |
670 | ||
671 | ||
672 | /* Let modules do char dev stuff */ | |
673 | EXPORT_SYMBOL(register_chrdev_region); | |
674 | EXPORT_SYMBOL(unregister_chrdev_region); | |
675 | EXPORT_SYMBOL(alloc_chrdev_region); | |
676 | EXPORT_SYMBOL(cdev_init); | |
677 | EXPORT_SYMBOL(cdev_alloc); | |
678 | EXPORT_SYMBOL(cdev_del); | |
679 | EXPORT_SYMBOL(cdev_add); | |
233ed09d LG |
680 | EXPORT_SYMBOL(cdev_set_parent); |
681 | EXPORT_SYMBOL(cdev_device_add); | |
682 | EXPORT_SYMBOL(cdev_device_del); | |
1905b1bf TH |
683 | EXPORT_SYMBOL(__register_chrdev); |
684 | EXPORT_SYMBOL(__unregister_chrdev); |