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Source at commit be977234bfb4a6dca8a39e7c52165e4cd536ad71 created 12 years 9 months ago. By Lars-Peter Clausen, jz4740: Fix compile error | |
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1 | /* |
2 | * linux/fs/char_dev.c |
3 | * |
4 | * Copyright (C) 1991, 1992 Linus Torvalds |
5 | */ |
6 | |
7 | #include <linux/init.h> |
8 | #include <linux/fs.h> |
9 | #include <linux/kdev_t.h> |
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> |
16 | #include <linux/seq_file.h> |
17 | |
18 | #include <linux/kobject.h> |
19 | #include <linux/kobj_map.h> |
20 | #include <linux/cdev.h> |
21 | #include <linux/mutex.h> |
22 | #include <linux/backing-dev.h> |
23 | #include <linux/tty.h> |
24 | |
25 | #include "internal.h" |
26 | |
27 | /* |
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 | */ |
34 | struct backing_dev_info directly_mappable_cdev_bdi = { |
35 | .name = "char", |
36 | .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 | |
43 | BDI_CAP_READ_MAP | BDI_CAP_WRITE_MAP | BDI_CAP_EXEC_MAP | |
44 | /* no writeback happens */ |
45 | BDI_CAP_NO_ACCT_AND_WRITEBACK), |
46 | }; |
47 | |
48 | static struct kobj_map *cdev_map; |
49 | |
50 | static DEFINE_MUTEX(chrdevs_lock); |
51 | |
52 | static struct char_device_struct { |
53 | struct char_device_struct *next; |
54 | unsigned int major; |
55 | unsigned int baseminor; |
56 | int minorct; |
57 | char name[64]; |
58 | struct cdev *cdev; /* will die */ |
59 | } *chrdevs[CHRDEV_MAJOR_HASH_SIZE]; |
60 | |
61 | /* index in the above */ |
62 | static inline int major_to_index(unsigned major) |
63 | { |
64 | return major % CHRDEV_MAJOR_HASH_SIZE; |
65 | } |
66 | |
67 | #ifdef CONFIG_PROC_FS |
68 | |
69 | void chrdev_show(struct seq_file *f, off_t offset) |
70 | { |
71 | struct char_device_struct *cd; |
72 | |
73 | 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); |
78 | } |
79 | } |
80 | |
81 | #endif /* CONFIG_PROC_FS */ |
82 | |
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 | */ |
94 | static 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 | |
102 | cd = kzalloc(sizeof(struct char_device_struct), GFP_KERNEL); |
103 | if (cd == NULL) |
104 | return ERR_PTR(-ENOMEM); |
105 | |
106 | mutex_lock(&chrdevs_lock); |
107 | |
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; |
120 | ret = major; |
121 | } |
122 | |
123 | cd->major = major; |
124 | cd->baseminor = baseminor; |
125 | cd->minorct = minorct; |
126 | strlcpy(cd->name, name, sizeof(cd->name)); |
127 | |
128 | i = major_to_index(major); |
129 | |
130 | for (cp = &chrdevs[i]; *cp; cp = &(*cp)->next) |
131 | if ((*cp)->major > major || |
132 | ((*cp)->major == major && |
133 | (((*cp)->baseminor >= baseminor) || |
134 | ((*cp)->baseminor + (*cp)->minorct > baseminor)))) |
135 | break; |
136 | |
137 | /* Check for overlapping minor ranges. */ |
138 | if (*cp && (*cp)->major == major) { |
139 | int old_min = (*cp)->baseminor; |
140 | int old_max = (*cp)->baseminor + (*cp)->minorct - 1; |
141 | int new_min = baseminor; |
142 | int new_max = baseminor + minorct - 1; |
143 | |
144 | /* New driver overlaps from the left. */ |
145 | if (new_max >= old_min && new_max <= old_max) { |
146 | ret = -EBUSY; |
147 | goto out; |
148 | } |
149 | |
150 | /* New driver overlaps from the right. */ |
151 | if (new_min <= old_max && new_min >= old_min) { |
152 | ret = -EBUSY; |
153 | goto out; |
154 | } |
155 | } |
156 | |
157 | cd->next = *cp; |
158 | *cp = cd; |
159 | mutex_unlock(&chrdevs_lock); |
160 | return cd; |
161 | out: |
162 | mutex_unlock(&chrdevs_lock); |
163 | kfree(cd); |
164 | return ERR_PTR(ret); |
165 | } |
166 | |
167 | static struct char_device_struct * |
168 | __unregister_chrdev_region(unsigned major, unsigned baseminor, int minorct) |
169 | { |
170 | struct char_device_struct *cd = NULL, **cp; |
171 | int i = major_to_index(major); |
172 | |
173 | mutex_lock(&chrdevs_lock); |
174 | for (cp = &chrdevs[i]; *cp; cp = &(*cp)->next) |
175 | if ((*cp)->major == major && |
176 | (*cp)->baseminor == baseminor && |
177 | (*cp)->minorct == minorct) |
178 | break; |
179 | if (*cp) { |
180 | cd = *cp; |
181 | *cp = cd->next; |
182 | } |
183 | mutex_unlock(&chrdevs_lock); |
184 | return cd; |
185 | } |
186 | |
187 | /** |
188 | * register_chrdev_region() - register a range of device numbers |
189 | * @from: the first in the desired range of device numbers; must include |
190 | * the major number. |
191 | * @count: the number of consecutive device numbers required |
192 | * @name: the name of the device or driver. |
193 | * |
194 | * Return value is zero on success, a negative error code on failure. |
195 | */ |
196 | int register_chrdev_region(dev_t from, unsigned count, const char *name) |
197 | { |
198 | struct char_device_struct *cd; |
199 | dev_t to = from + count; |
200 | dev_t n, next; |
201 | |
202 | for (n = from; n < to; n = next) { |
203 | next = MKDEV(MAJOR(n)+1, 0); |
204 | if (next > to) |
205 | next = to; |
206 | cd = __register_chrdev_region(MAJOR(n), MINOR(n), |
207 | next - n, name); |
208 | if (IS_ERR(cd)) |
209 | goto fail; |
210 | } |
211 | return 0; |
212 | fail: |
213 | to = n; |
214 | for (n = from; n < to; n = next) { |
215 | next = MKDEV(MAJOR(n)+1, 0); |
216 | kfree(__unregister_chrdev_region(MAJOR(n), MINOR(n), next - n)); |
217 | } |
218 | return PTR_ERR(cd); |
219 | } |
220 | |
221 | /** |
222 | * alloc_chrdev_region() - register a range of char device numbers |
223 | * @dev: output parameter for first assigned number |
224 | * @baseminor: first of the requested range of minor numbers |
225 | * @count: the number of minor numbers required |
226 | * @name: the name of the associated device or driver |
227 | * |
228 | * Allocates a range of char device numbers. The major number will be |
229 | * chosen dynamically, and returned (along with the first minor number) |
230 | * in @dev. Returns zero or a negative error code. |
231 | */ |
232 | int alloc_chrdev_region(dev_t *dev, unsigned baseminor, unsigned count, |
233 | const char *name) |
234 | { |
235 | struct char_device_struct *cd; |
236 | cd = __register_chrdev_region(0, baseminor, count, name); |
237 | if (IS_ERR(cd)) |
238 | return PTR_ERR(cd); |
239 | *dev = MKDEV(cd->major, cd->baseminor); |
240 | return 0; |
241 | } |
242 | |
243 | /** |
244 | * __register_chrdev() - create and register a cdev occupying a range of minors |
245 | * @major: major device number or 0 for dynamic allocation |
246 | * @baseminor: first of the requested range of minor numbers |
247 | * @count: the number of minor numbers required |
248 | * @name: name of this range of devices |
249 | * @fops: file operations associated with this devices |
250 | * |
251 | * If @major == 0 this functions will dynamically allocate a major and return |
252 | * its number. |
253 | * |
254 | * If @major > 0 this function will attempt to reserve a device with the given |
255 | * major number and will return zero on success. |
256 | * |
257 | * Returns a -ve errno on failure. |
258 | * |
259 | * The name of this device has nothing to do with the name of the device in |
260 | * /dev. It only helps to keep track of the different owners of devices. If |
261 | * your module name has only one type of devices it's ok to use e.g. the name |
262 | * of the module here. |
263 | */ |
264 | int __register_chrdev(unsigned int major, unsigned int baseminor, |
265 | unsigned int count, const char *name, |
266 | const struct file_operations *fops) |
267 | { |
268 | struct char_device_struct *cd; |
269 | struct cdev *cdev; |
270 | int err = -ENOMEM; |
271 | |
272 | cd = __register_chrdev_region(major, baseminor, count, name); |
273 | if (IS_ERR(cd)) |
274 | return PTR_ERR(cd); |
275 | |
276 | cdev = cdev_alloc(); |
277 | if (!cdev) |
278 | goto out2; |
279 | |
280 | cdev->owner = fops->owner; |
281 | cdev->ops = fops; |
282 | kobject_set_name(&cdev->kobj, "%s", name); |
283 | |
284 | err = cdev_add(cdev, MKDEV(cd->major, baseminor), count); |
285 | if (err) |
286 | goto out; |
287 | |
288 | cd->cdev = cdev; |
289 | |
290 | return major ? 0 : cd->major; |
291 | out: |
292 | kobject_put(&cdev->kobj); |
293 | out2: |
294 | kfree(__unregister_chrdev_region(cd->major, baseminor, count)); |
295 | return err; |
296 | } |
297 | |
298 | /** |
299 | * unregister_chrdev_region() - return a range of device numbers |
300 | * @from: the first in the range of numbers to unregister |
301 | * @count: the number of device numbers to unregister |
302 | * |
303 | * This function will unregister a range of @count device numbers, |
304 | * starting with @from. The caller should normally be the one who |
305 | * allocated those numbers in the first place... |
306 | */ |
307 | void unregister_chrdev_region(dev_t from, unsigned count) |
308 | { |
309 | dev_t to = from + count; |
310 | dev_t n, next; |
311 | |
312 | for (n = from; n < to; n = next) { |
313 | next = MKDEV(MAJOR(n)+1, 0); |
314 | if (next > to) |
315 | next = to; |
316 | kfree(__unregister_chrdev_region(MAJOR(n), MINOR(n), next - n)); |
317 | } |
318 | } |
319 | |
320 | /** |
321 | * __unregister_chrdev - unregister and destroy a cdev |
322 | * @major: major device number |
323 | * @baseminor: first of the range of minor numbers |
324 | * @count: the number of minor numbers this cdev is occupying |
325 | * @name: name of this range of devices |
326 | * |
327 | * Unregister and destroy the cdev occupying the region described by |
328 | * @major, @baseminor and @count. This function undoes what |
329 | * __register_chrdev() did. |
330 | */ |
331 | void __unregister_chrdev(unsigned int major, unsigned int baseminor, |
332 | unsigned int count, const char *name) |
333 | { |
334 | struct char_device_struct *cd; |
335 | |
336 | cd = __unregister_chrdev_region(major, baseminor, count); |
337 | if (cd && cd->cdev) |
338 | cdev_del(cd->cdev); |
339 | kfree(cd); |
340 | } |
341 | |
342 | static DEFINE_SPINLOCK(cdev_lock); |
343 | |
344 | static struct kobject *cdev_get(struct cdev *p) |
345 | { |
346 | struct module *owner = p->owner; |
347 | struct kobject *kobj; |
348 | |
349 | if (owner && !try_module_get(owner)) |
350 | return NULL; |
351 | kobj = kobject_get(&p->kobj); |
352 | if (!kobj) |
353 | module_put(owner); |
354 | return kobj; |
355 | } |
356 | |
357 | void cdev_put(struct cdev *p) |
358 | { |
359 | if (p) { |
360 | struct module *owner = p->owner; |
361 | kobject_put(&p->kobj); |
362 | module_put(owner); |
363 | } |
364 | } |
365 | |
366 | /* |
367 | * Called every time a character special file is opened |
368 | */ |
369 | static int chrdev_open(struct inode *inode, struct file *filp) |
370 | { |
371 | 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); |
386 | /* Check i_cdev again in case somebody beat us to it while |
387 | we dropped the lock. */ |
388 | p = inode->i_cdev; |
389 | if (!p) { |
390 | inode->i_cdev = p = new; |
391 | 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; |
401 | |
402 | ret = -ENXIO; |
403 | filp->f_op = fops_get(p->ops); |
404 | if (!filp->f_op) |
405 | goto out_cdev_put; |
406 | |
407 | if (filp->f_op->open) { |
408 | ret = filp->f_op->open(inode,filp); |
409 | if (ret) |
410 | goto out_cdev_put; |
411 | } |
412 | |
413 | return 0; |
414 | |
415 | out_cdev_put: |
416 | cdev_put(p); |
417 | return ret; |
418 | } |
419 | |
420 | void cd_forget(struct inode *inode) |
421 | { |
422 | spin_lock(&cdev_lock); |
423 | list_del_init(&inode->i_devices); |
424 | inode->i_cdev = NULL; |
425 | spin_unlock(&cdev_lock); |
426 | } |
427 | |
428 | static void cdev_purge(struct cdev *cdev) |
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 | */ |
445 | const struct file_operations def_chr_fops = { |
446 | .open = chrdev_open, |
447 | .llseek = noop_llseek, |
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 | |
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 | */ |
472 | int cdev_add(struct cdev *p, dev_t dev, unsigned count) |
473 | { |
474 | p->dev = dev; |
475 | p->count = count; |
476 | return kobj_map(cdev_map, dev, count, NULL, exact_match, exact_lock, p); |
477 | } |
478 | |
479 | static void cdev_unmap(dev_t dev, unsigned count) |
480 | { |
481 | kobj_unmap(cdev_map, dev, count); |
482 | } |
483 | |
484 | /** |
485 | * cdev_del() - remove a cdev from the system |
486 | * @p: the cdev structure to be removed |
487 | * |
488 | * cdev_del() removes @p from the system, possibly freeing the structure |
489 | * itself. |
490 | */ |
491 | void cdev_del(struct cdev *p) |
492 | { |
493 | cdev_unmap(p->dev, p->count); |
494 | kobject_put(&p->kobj); |
495 | } |
496 | |
497 | |
498 | static void cdev_default_release(struct kobject *kobj) |
499 | { |
500 | struct cdev *p = container_of(kobj, struct cdev, kobj); |
501 | cdev_purge(p); |
502 | } |
503 | |
504 | static void cdev_dynamic_release(struct kobject *kobj) |
505 | { |
506 | struct cdev *p = container_of(kobj, struct cdev, kobj); |
507 | cdev_purge(p); |
508 | kfree(p); |
509 | } |
510 | |
511 | static struct kobj_type ktype_cdev_default = { |
512 | .release = cdev_default_release, |
513 | }; |
514 | |
515 | static struct kobj_type ktype_cdev_dynamic = { |
516 | .release = cdev_dynamic_release, |
517 | }; |
518 | |
519 | /** |
520 | * cdev_alloc() - allocate a cdev structure |
521 | * |
522 | * Allocates and returns a cdev structure, or NULL on failure. |
523 | */ |
524 | struct cdev *cdev_alloc(void) |
525 | { |
526 | struct cdev *p = kzalloc(sizeof(struct cdev), GFP_KERNEL); |
527 | if (p) { |
528 | INIT_LIST_HEAD(&p->list); |
529 | kobject_init(&p->kobj, &ktype_cdev_dynamic); |
530 | } |
531 | return p; |
532 | } |
533 | |
534 | /** |
535 | * cdev_init() - initialize a cdev structure |
536 | * @cdev: the structure to initialize |
537 | * @fops: the file_operations for this device |
538 | * |
539 | * Initializes @cdev, remembering @fops, making it ready to add to the |
540 | * system with cdev_add(). |
541 | */ |
542 | void cdev_init(struct cdev *cdev, const struct file_operations *fops) |
543 | { |
544 | memset(cdev, 0, sizeof *cdev); |
545 | INIT_LIST_HEAD(&cdev->list); |
546 | kobject_init(&cdev->kobj, &ktype_cdev_default); |
547 | cdev->ops = fops; |
548 | } |
549 | |
550 | static struct kobject *base_probe(dev_t dev, int *part, void *data) |
551 | { |
552 | if (request_module("char-major-%d-%d", MAJOR(dev), MINOR(dev)) > 0) |
553 | /* Make old-style 2.4 aliases work */ |
554 | request_module("char-major-%d", MAJOR(dev)); |
555 | return NULL; |
556 | } |
557 | |
558 | void __init chrdev_init(void) |
559 | { |
560 | cdev_map = kobj_map_init(base_probe, &chrdevs_lock); |
561 | bdi_init(&directly_mappable_cdev_bdi); |
562 | } |
563 | |
564 | |
565 | /* Let modules do char dev stuff */ |
566 | EXPORT_SYMBOL(register_chrdev_region); |
567 | EXPORT_SYMBOL(unregister_chrdev_region); |
568 | EXPORT_SYMBOL(alloc_chrdev_region); |
569 | EXPORT_SYMBOL(cdev_init); |
570 | EXPORT_SYMBOL(cdev_alloc); |
571 | EXPORT_SYMBOL(cdev_del); |
572 | EXPORT_SYMBOL(cdev_add); |
573 | EXPORT_SYMBOL(__register_chrdev); |
574 | EXPORT_SYMBOL(__unregister_chrdev); |
575 | EXPORT_SYMBOL(directly_mappable_cdev_bdi); |
576 |
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