blob: 67b2007f10fe65986a05d3af07e3b2b99ded7c61 [file] [log] [blame]
Linus Torvalds1da177e2005-04-16 15:20:36 -07001/*
2 * linux/fs/char_dev.c
3 *
4 * Copyright (C) 1991, 1992 Linus Torvalds
5 */
6
Linus Torvalds1da177e2005-04-16 15:20:36 -07007#include <linux/init.h>
8#include <linux/fs.h>
Andrew Mortonb446b602007-02-20 13:57:48 -08009#include <linux/kdev_t.h>
Linus Torvalds1da177e2005-04-16 15:20:36 -070010#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>
Joe Korty68eef3b2006-03-31 02:30:32 -080016#include <linux/seq_file.h>
Linus Torvalds1da177e2005-04-16 15:20:36 -070017
18#include <linux/kobject.h>
19#include <linux/kobj_map.h>
20#include <linux/cdev.h>
Jes Sorensen58383af2006-02-06 14:12:43 -080021#include <linux/mutex.h>
David Howells5da61852006-09-27 01:50:16 -070022#include <linux/backing-dev.h>
David Howells31d1d482010-08-06 16:34:43 +010023#include <linux/tty.h>
Linus Torvalds1da177e2005-04-16 15:20:36 -070024
David Howells07f3f052006-09-30 20:52:18 +020025#include "internal.h"
Linus Torvalds1da177e2005-04-16 15:20:36 -070026
David Howells5da61852006-09-27 01:50:16 -070027/*
28 * capabilities for /dev/mem, /dev/kmem and similar directly mappable character
29 * devices
30 * - permits shared-mmap for read, write and/or exec
31 * - does not permit private mmap in NOMMU mode (can't do COW)
32 * - no readahead or I/O queue unplugging required
33 */
34struct backing_dev_info directly_mappable_cdev_bdi = {
Jens Axboed9938312009-06-12 14:45:52 +020035 .name = "char",
David Howells5da61852006-09-27 01:50:16 -070036 .capabilities = (
37#ifdef CONFIG_MMU
38 /* permit private copies of the data to be taken */
39 BDI_CAP_MAP_COPY |
40#endif
41 /* permit direct mmap, for read, write or exec */
42 BDI_CAP_MAP_DIRECT |
Jan Kara371d2172010-09-21 11:49:01 +020043 BDI_CAP_READ_MAP | BDI_CAP_WRITE_MAP | BDI_CAP_EXEC_MAP |
44 /* no writeback happens */
45 BDI_CAP_NO_ACCT_AND_WRITEBACK),
David Howells5da61852006-09-27 01:50:16 -070046};
47
Linus Torvalds1da177e2005-04-16 15:20:36 -070048static struct kobj_map *cdev_map;
49
Jes Sorensen58383af2006-02-06 14:12:43 -080050static DEFINE_MUTEX(chrdevs_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -070051
52static struct char_device_struct {
53 struct char_device_struct *next;
54 unsigned int major;
55 unsigned int baseminor;
56 int minorct;
Neil Horman7170be52006-01-14 13:20:38 -080057 char name[64];
Linus Torvalds1da177e2005-04-16 15:20:36 -070058 struct cdev *cdev; /* will die */
Joe Korty68eef3b2006-03-31 02:30:32 -080059} *chrdevs[CHRDEV_MAJOR_HASH_SIZE];
Linus Torvalds1da177e2005-04-16 15:20:36 -070060
61/* index in the above */
Yang Zhange61eb2e2010-12-17 09:00:18 +010062static inline int major_to_index(unsigned major)
Linus Torvalds1da177e2005-04-16 15:20:36 -070063{
Joe Korty68eef3b2006-03-31 02:30:32 -080064 return major % CHRDEV_MAJOR_HASH_SIZE;
Linus Torvalds1da177e2005-04-16 15:20:36 -070065}
66
Joe Korty68eef3b2006-03-31 02:30:32 -080067#ifdef CONFIG_PROC_FS
Neil Horman7170be52006-01-14 13:20:38 -080068
Joe Korty68eef3b2006-03-31 02:30:32 -080069void chrdev_show(struct seq_file *f, off_t offset)
Linus Torvalds1da177e2005-04-16 15:20:36 -070070{
71 struct char_device_struct *cd;
Linus Torvalds1da177e2005-04-16 15:20:36 -070072
Joe Korty68eef3b2006-03-31 02:30:32 -080073 if (offset < CHRDEV_MAJOR_HASH_SIZE) {
74 mutex_lock(&chrdevs_lock);
75 for (cd = chrdevs[offset]; cd; cd = cd->next)
76 seq_printf(f, "%3d %s\n", cd->major, cd->name);
77 mutex_unlock(&chrdevs_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -070078 }
Neil Horman7170be52006-01-14 13:20:38 -080079}
80
Joe Korty68eef3b2006-03-31 02:30:32 -080081#endif /* CONFIG_PROC_FS */
Linus Torvalds1da177e2005-04-16 15:20:36 -070082
83/*
84 * Register a single major with a specified minor range.
85 *
86 * If major == 0 this functions will dynamically allocate a major and return
87 * its number.
88 *
89 * If major > 0 this function will attempt to reserve the passed range of
90 * minors and will return zero on success.
91 *
92 * Returns a -ve errno on failure.
93 */
94static struct char_device_struct *
95__register_chrdev_region(unsigned int major, unsigned int baseminor,
96 int minorct, const char *name)
97{
98 struct char_device_struct *cd, **cp;
99 int ret = 0;
100 int i;
101
Oliver Neukum11b0b5a2006-03-25 03:08:13 -0800102 cd = kzalloc(sizeof(struct char_device_struct), GFP_KERNEL);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700103 if (cd == NULL)
104 return ERR_PTR(-ENOMEM);
105
Jes Sorensen58383af2006-02-06 14:12:43 -0800106 mutex_lock(&chrdevs_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700107
108 /* temporary */
109 if (major == 0) {
110 for (i = ARRAY_SIZE(chrdevs)-1; i > 0; i--) {
111 if (chrdevs[i] == NULL)
112 break;
113 }
114
115 if (i == 0) {
116 ret = -EBUSY;
117 goto out;
118 }
119 major = i;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700120 }
121
122 cd->major = major;
123 cd->baseminor = baseminor;
124 cd->minorct = minorct;
Cyrill Gorcunov8c401882009-01-06 14:41:08 -0800125 strlcpy(cd->name, name, sizeof(cd->name));
Linus Torvalds1da177e2005-04-16 15:20:36 -0700126
127 i = major_to_index(major);
128
129 for (cp = &chrdevs[i]; *cp; cp = &(*cp)->next)
130 if ((*cp)->major > major ||
Amos Waterland01d553d2006-09-29 02:00:08 -0700131 ((*cp)->major == major &&
132 (((*cp)->baseminor >= baseminor) ||
133 ((*cp)->baseminor + (*cp)->minorct > baseminor))))
Linus Torvalds1da177e2005-04-16 15:20:36 -0700134 break;
Amos Waterland01d553d2006-09-29 02:00:08 -0700135
136 /* Check for overlapping minor ranges. */
137 if (*cp && (*cp)->major == major) {
138 int old_min = (*cp)->baseminor;
139 int old_max = (*cp)->baseminor + (*cp)->minorct - 1;
140 int new_min = baseminor;
141 int new_max = baseminor + minorct - 1;
142
143 /* New driver overlaps from the left. */
144 if (new_max >= old_min && new_max <= old_max) {
145 ret = -EBUSY;
146 goto out;
147 }
148
149 /* New driver overlaps from the right. */
150 if (new_min <= old_max && new_min >= old_min) {
151 ret = -EBUSY;
152 goto out;
153 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700154 }
Amos Waterland01d553d2006-09-29 02:00:08 -0700155
Linus Torvalds1da177e2005-04-16 15:20:36 -0700156 cd->next = *cp;
157 *cp = cd;
Jes Sorensen58383af2006-02-06 14:12:43 -0800158 mutex_unlock(&chrdevs_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700159 return cd;
160out:
Jes Sorensen58383af2006-02-06 14:12:43 -0800161 mutex_unlock(&chrdevs_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700162 kfree(cd);
163 return ERR_PTR(ret);
164}
165
166static struct char_device_struct *
167__unregister_chrdev_region(unsigned major, unsigned baseminor, int minorct)
168{
169 struct char_device_struct *cd = NULL, **cp;
170 int i = major_to_index(major);
171
Jes Sorensen58383af2006-02-06 14:12:43 -0800172 mutex_lock(&chrdevs_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700173 for (cp = &chrdevs[i]; *cp; cp = &(*cp)->next)
174 if ((*cp)->major == major &&
175 (*cp)->baseminor == baseminor &&
176 (*cp)->minorct == minorct)
177 break;
178 if (*cp) {
179 cd = *cp;
180 *cp = cd->next;
181 }
Jes Sorensen58383af2006-02-06 14:12:43 -0800182 mutex_unlock(&chrdevs_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700183 return cd;
184}
185
Jonathan Corbetcf3e43d2006-09-29 02:00:44 -0700186/**
187 * register_chrdev_region() - register a range of device numbers
188 * @from: the first in the desired range of device numbers; must include
189 * the major number.
190 * @count: the number of consecutive device numbers required
191 * @name: the name of the device or driver.
192 *
193 * Return value is zero on success, a negative error code on failure.
194 */
Linus Torvalds1da177e2005-04-16 15:20:36 -0700195int register_chrdev_region(dev_t from, unsigned count, const char *name)
196{
197 struct char_device_struct *cd;
198 dev_t to = from + count;
199 dev_t n, next;
200
201 for (n = from; n < to; n = next) {
202 next = MKDEV(MAJOR(n)+1, 0);
203 if (next > to)
204 next = to;
205 cd = __register_chrdev_region(MAJOR(n), MINOR(n),
206 next - n, name);
207 if (IS_ERR(cd))
208 goto fail;
209 }
210 return 0;
211fail:
212 to = n;
213 for (n = from; n < to; n = next) {
214 next = MKDEV(MAJOR(n)+1, 0);
215 kfree(__unregister_chrdev_region(MAJOR(n), MINOR(n), next - n));
216 }
217 return PTR_ERR(cd);
218}
219
Jonathan Corbetcf3e43d2006-09-29 02:00:44 -0700220/**
221 * alloc_chrdev_region() - register a range of char device numbers
222 * @dev: output parameter for first assigned number
223 * @baseminor: first of the requested range of minor numbers
224 * @count: the number of minor numbers required
225 * @name: the name of the associated device or driver
226 *
227 * Allocates a range of char device numbers. The major number will be
228 * chosen dynamically, and returned (along with the first minor number)
229 * in @dev. Returns zero or a negative error code.
230 */
Linus Torvalds1da177e2005-04-16 15:20:36 -0700231int alloc_chrdev_region(dev_t *dev, unsigned baseminor, unsigned count,
232 const char *name)
233{
234 struct char_device_struct *cd;
235 cd = __register_chrdev_region(0, baseminor, count, name);
236 if (IS_ERR(cd))
237 return PTR_ERR(cd);
238 *dev = MKDEV(cd->major, cd->baseminor);
239 return 0;
240}
241
Rolf Eike Beerd247e2c2006-07-14 00:24:23 -0700242/**
Tejun Heo1905b1b2009-08-06 18:13:23 +0900243 * __register_chrdev() - create and register a cdev occupying a range of minors
Rolf Eike Beerd247e2c2006-07-14 00:24:23 -0700244 * @major: major device number or 0 for dynamic allocation
Tejun Heo1905b1b2009-08-06 18:13:23 +0900245 * @baseminor: first of the requested range of minor numbers
246 * @count: the number of minor numbers required
Rolf Eike Beerd247e2c2006-07-14 00:24:23 -0700247 * @name: name of this range of devices
248 * @fops: file operations associated with this devices
249 *
250 * If @major == 0 this functions will dynamically allocate a major and return
251 * its number.
252 *
253 * If @major > 0 this function will attempt to reserve a device with the given
254 * major number and will return zero on success.
255 *
256 * Returns a -ve errno on failure.
257 *
258 * The name of this device has nothing to do with the name of the device in
259 * /dev. It only helps to keep track of the different owners of devices. If
260 * your module name has only one type of devices it's ok to use e.g. the name
261 * of the module here.
Rolf Eike Beerd247e2c2006-07-14 00:24:23 -0700262 */
Tejun Heo1905b1b2009-08-06 18:13:23 +0900263int __register_chrdev(unsigned int major, unsigned int baseminor,
264 unsigned int count, const char *name,
265 const struct file_operations *fops)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700266{
267 struct char_device_struct *cd;
268 struct cdev *cdev;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700269 int err = -ENOMEM;
270
Tejun Heo1905b1b2009-08-06 18:13:23 +0900271 cd = __register_chrdev_region(major, baseminor, count, name);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700272 if (IS_ERR(cd))
273 return PTR_ERR(cd);
Greg Kroah-Hartman1ff97642011-12-13 11:06:49 -0800274
Linus Torvalds1da177e2005-04-16 15:20:36 -0700275 cdev = cdev_alloc();
276 if (!cdev)
277 goto out2;
278
279 cdev->owner = fops->owner;
280 cdev->ops = fops;
281 kobject_set_name(&cdev->kobj, "%s", name);
Greg Kroah-Hartman1ff97642011-12-13 11:06:49 -0800282
Tejun Heo1905b1b2009-08-06 18:13:23 +0900283 err = cdev_add(cdev, MKDEV(cd->major, baseminor), count);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700284 if (err)
285 goto out;
286
287 cd->cdev = cdev;
288
289 return major ? 0 : cd->major;
290out:
291 kobject_put(&cdev->kobj);
292out2:
Tejun Heo1905b1b2009-08-06 18:13:23 +0900293 kfree(__unregister_chrdev_region(cd->major, baseminor, count));
Linus Torvalds1da177e2005-04-16 15:20:36 -0700294 return err;
295}
296
Jonathan Corbetcf3e43d2006-09-29 02:00:44 -0700297/**
298 * unregister_chrdev_region() - return a range of device numbers
299 * @from: the first in the range of numbers to unregister
300 * @count: the number of device numbers to unregister
301 *
302 * This function will unregister a range of @count device numbers,
303 * starting with @from. The caller should normally be the one who
304 * allocated those numbers in the first place...
305 */
Linus Torvalds1da177e2005-04-16 15:20:36 -0700306void unregister_chrdev_region(dev_t from, unsigned count)
307{
308 dev_t to = from + count;
309 dev_t n, next;
310
311 for (n = from; n < to; n = next) {
312 next = MKDEV(MAJOR(n)+1, 0);
313 if (next > to)
314 next = to;
315 kfree(__unregister_chrdev_region(MAJOR(n), MINOR(n), next - n));
316 }
317}
318
Tejun Heo1905b1b2009-08-06 18:13:23 +0900319/**
320 * __unregister_chrdev - unregister and destroy a cdev
321 * @major: major device number
322 * @baseminor: first of the range of minor numbers
323 * @count: the number of minor numbers this cdev is occupying
324 * @name: name of this range of devices
325 *
326 * Unregister and destroy the cdev occupying the region described by
327 * @major, @baseminor and @count. This function undoes what
328 * __register_chrdev() did.
329 */
330void __unregister_chrdev(unsigned int major, unsigned int baseminor,
331 unsigned int count, const char *name)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700332{
333 struct char_device_struct *cd;
Tejun Heo1905b1b2009-08-06 18:13:23 +0900334
335 cd = __unregister_chrdev_region(major, baseminor, count);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700336 if (cd && cd->cdev)
337 cdev_del(cd->cdev);
338 kfree(cd);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700339}
340
341static DEFINE_SPINLOCK(cdev_lock);
342
343static struct kobject *cdev_get(struct cdev *p)
344{
345 struct module *owner = p->owner;
346 struct kobject *kobj;
347
348 if (owner && !try_module_get(owner))
349 return NULL;
350 kobj = kobject_get(&p->kobj);
351 if (!kobj)
352 module_put(owner);
353 return kobj;
354}
355
356void cdev_put(struct cdev *p)
357{
358 if (p) {
Brian King7da68442005-07-12 13:58:30 -0700359 struct module *owner = p->owner;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700360 kobject_put(&p->kobj);
Brian King7da68442005-07-12 13:58:30 -0700361 module_put(owner);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700362 }
363}
364
365/*
366 * Called every time a character special file is opened
367 */
Denis Cheng922f9cf2008-02-08 04:22:00 -0800368static int chrdev_open(struct inode *inode, struct file *filp)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700369{
Al Viroe84f9e52013-09-22 14:17:15 -0400370 const struct file_operations *fops;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700371 struct cdev *p;
372 struct cdev *new = NULL;
373 int ret = 0;
374
375 spin_lock(&cdev_lock);
376 p = inode->i_cdev;
377 if (!p) {
378 struct kobject *kobj;
379 int idx;
380 spin_unlock(&cdev_lock);
381 kobj = kobj_lookup(cdev_map, inode->i_rdev, &idx);
382 if (!kobj)
383 return -ENXIO;
384 new = container_of(kobj, struct cdev, kobj);
385 spin_lock(&cdev_lock);
Jonathan Corbeta30427d2008-05-18 15:39:11 -0600386 /* Check i_cdev again in case somebody beat us to it while
387 we dropped the lock. */
Linus Torvalds1da177e2005-04-16 15:20:36 -0700388 p = inode->i_cdev;
389 if (!p) {
390 inode->i_cdev = p = new;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700391 list_add(&inode->i_devices, &p->list);
392 new = NULL;
393 } else if (!cdev_get(p))
394 ret = -ENXIO;
395 } else if (!cdev_get(p))
396 ret = -ENXIO;
397 spin_unlock(&cdev_lock);
398 cdev_put(new);
399 if (ret)
400 return ret;
Christoph Hellwiga518ab92008-08-11 15:34:22 +0200401
402 ret = -ENXIO;
Al Viroe84f9e52013-09-22 14:17:15 -0400403 fops = fops_get(p->ops);
404 if (!fops)
Christoph Hellwiga518ab92008-08-11 15:34:22 +0200405 goto out_cdev_put;
406
Al Viroe84f9e52013-09-22 14:17:15 -0400407 replace_fops(filp, fops);
Christoph Hellwiga518ab92008-08-11 15:34:22 +0200408 if (filp->f_op->open) {
Greg Kroah-Hartman1ff97642011-12-13 11:06:49 -0800409 ret = filp->f_op->open(inode, filp);
Christoph Hellwiga518ab92008-08-11 15:34:22 +0200410 if (ret)
411 goto out_cdev_put;
412 }
413
414 return 0;
415
416 out_cdev_put:
417 cdev_put(p);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700418 return ret;
419}
420
421void cd_forget(struct inode *inode)
422{
423 spin_lock(&cdev_lock);
424 list_del_init(&inode->i_devices);
425 inode->i_cdev = NULL;
426 spin_unlock(&cdev_lock);
427}
428
Adrian Bunk75c96f82005-05-05 16:16:09 -0700429static void cdev_purge(struct cdev *cdev)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700430{
431 spin_lock(&cdev_lock);
432 while (!list_empty(&cdev->list)) {
433 struct inode *inode;
434 inode = container_of(cdev->list.next, struct inode, i_devices);
435 list_del_init(&inode->i_devices);
436 inode->i_cdev = NULL;
437 }
438 spin_unlock(&cdev_lock);
439}
440
441/*
442 * Dummy default file-operations: the only thing this does
443 * is contain the open that then fills in the correct operations
444 * depending on the special file...
445 */
Arjan van de Ven4b6f5d22006-03-28 01:56:42 -0800446const struct file_operations def_chr_fops = {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700447 .open = chrdev_open,
Arnd Bergmann6038f372010-08-15 18:52:59 +0200448 .llseek = noop_llseek,
Linus Torvalds1da177e2005-04-16 15:20:36 -0700449};
450
451static struct kobject *exact_match(dev_t dev, int *part, void *data)
452{
453 struct cdev *p = data;
454 return &p->kobj;
455}
456
457static int exact_lock(dev_t dev, void *data)
458{
459 struct cdev *p = data;
460 return cdev_get(p) ? 0 : -1;
461}
462
Jonathan Corbetcf3e43d2006-09-29 02:00:44 -0700463/**
464 * cdev_add() - add a char device to the system
465 * @p: the cdev structure for the device
466 * @dev: the first device number for which this device is responsible
467 * @count: the number of consecutive minor numbers corresponding to this
468 * device
469 *
470 * cdev_add() adds the device represented by @p to the system, making it
471 * live immediately. A negative error code is returned on failure.
472 */
Linus Torvalds1da177e2005-04-16 15:20:36 -0700473int cdev_add(struct cdev *p, dev_t dev, unsigned count)
474{
Dmitry Torokhov2f0157f2012-10-21 17:57:19 -0700475 int error;
476
Linus Torvalds1da177e2005-04-16 15:20:36 -0700477 p->dev = dev;
478 p->count = count;
Dmitry Torokhov2f0157f2012-10-21 17:57:19 -0700479
480 error = kobj_map(cdev_map, dev, count, NULL,
481 exact_match, exact_lock, p);
482 if (error)
483 return error;
484
485 kobject_get(p->kobj.parent);
486
487 return 0;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700488}
489
490static void cdev_unmap(dev_t dev, unsigned count)
491{
492 kobj_unmap(cdev_map, dev, count);
493}
494
Jonathan Corbetcf3e43d2006-09-29 02:00:44 -0700495/**
496 * cdev_del() - remove a cdev from the system
497 * @p: the cdev structure to be removed
498 *
499 * cdev_del() removes @p from the system, possibly freeing the structure
500 * itself.
501 */
Linus Torvalds1da177e2005-04-16 15:20:36 -0700502void cdev_del(struct cdev *p)
503{
504 cdev_unmap(p->dev, p->count);
505 kobject_put(&p->kobj);
506}
507
508
509static void cdev_default_release(struct kobject *kobj)
510{
511 struct cdev *p = container_of(kobj, struct cdev, kobj);
Dmitry Torokhov2f0157f2012-10-21 17:57:19 -0700512 struct kobject *parent = kobj->parent;
513
Linus Torvalds1da177e2005-04-16 15:20:36 -0700514 cdev_purge(p);
Dmitry Torokhov2f0157f2012-10-21 17:57:19 -0700515 kobject_put(parent);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700516}
517
518static void cdev_dynamic_release(struct kobject *kobj)
519{
520 struct cdev *p = container_of(kobj, struct cdev, kobj);
Dmitry Torokhov2f0157f2012-10-21 17:57:19 -0700521 struct kobject *parent = kobj->parent;
522
Linus Torvalds1da177e2005-04-16 15:20:36 -0700523 cdev_purge(p);
524 kfree(p);
Dmitry Torokhov2f0157f2012-10-21 17:57:19 -0700525 kobject_put(parent);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700526}
527
528static struct kobj_type ktype_cdev_default = {
529 .release = cdev_default_release,
530};
531
532static struct kobj_type ktype_cdev_dynamic = {
533 .release = cdev_dynamic_release,
534};
535
Jonathan Corbetcf3e43d2006-09-29 02:00:44 -0700536/**
537 * cdev_alloc() - allocate a cdev structure
538 *
539 * Allocates and returns a cdev structure, or NULL on failure.
540 */
Linus Torvalds1da177e2005-04-16 15:20:36 -0700541struct cdev *cdev_alloc(void)
542{
Oliver Neukum11b0b5a2006-03-25 03:08:13 -0800543 struct cdev *p = kzalloc(sizeof(struct cdev), GFP_KERNEL);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700544 if (p) {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700545 INIT_LIST_HEAD(&p->list);
Greg Kroah-Hartmanf9cb0742007-12-17 23:05:35 -0700546 kobject_init(&p->kobj, &ktype_cdev_dynamic);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700547 }
548 return p;
549}
550
Jonathan Corbetcf3e43d2006-09-29 02:00:44 -0700551/**
552 * cdev_init() - initialize a cdev structure
553 * @cdev: the structure to initialize
554 * @fops: the file_operations for this device
555 *
556 * Initializes @cdev, remembering @fops, making it ready to add to the
557 * system with cdev_add().
558 */
Arjan van de Ven99ac48f2006-03-28 01:56:41 -0800559void cdev_init(struct cdev *cdev, const struct file_operations *fops)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700560{
561 memset(cdev, 0, sizeof *cdev);
562 INIT_LIST_HEAD(&cdev->list);
Greg Kroah-Hartmanf9cb0742007-12-17 23:05:35 -0700563 kobject_init(&cdev->kobj, &ktype_cdev_default);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700564 cdev->ops = fops;
565}
566
567static struct kobject *base_probe(dev_t dev, int *part, void *data)
568{
569 if (request_module("char-major-%d-%d", MAJOR(dev), MINOR(dev)) > 0)
570 /* Make old-style 2.4 aliases work */
571 request_module("char-major-%d", MAJOR(dev));
572 return NULL;
573}
574
575void __init chrdev_init(void)
576{
577 cdev_map = kobj_map_init(base_probe, &chrdevs_lock);
Mikulas Patocka8077c0d2013-10-14 12:14:13 -0400578 if (bdi_init(&directly_mappable_cdev_bdi))
579 panic("Failed to init directly mappable cdev bdi");
Linus Torvalds1da177e2005-04-16 15:20:36 -0700580}
581
582
583/* Let modules do char dev stuff */
584EXPORT_SYMBOL(register_chrdev_region);
585EXPORT_SYMBOL(unregister_chrdev_region);
586EXPORT_SYMBOL(alloc_chrdev_region);
587EXPORT_SYMBOL(cdev_init);
588EXPORT_SYMBOL(cdev_alloc);
589EXPORT_SYMBOL(cdev_del);
590EXPORT_SYMBOL(cdev_add);
Tejun Heo1905b1b2009-08-06 18:13:23 +0900591EXPORT_SYMBOL(__register_chrdev);
592EXPORT_SYMBOL(__unregister_chrdev);
David Howells5da61852006-09-27 01:50:16 -0700593EXPORT_SYMBOL(directly_mappable_cdev_bdi);