Commit | Line | Data |
---|---|---|
1da177e4 LT |
1 | /* |
2 | * linux/fs/char_dev.c | |
3 | * | |
4 | * Copyright (C) 1991, 1992 Linus Torvalds | |
5 | */ | |
6 | ||
7 | #include <linux/config.h> | |
8 | #include <linux/init.h> | |
9 | #include <linux/fs.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/smp_lock.h> | |
17 | #include <linux/devfs_fs_kernel.h> | |
18 | ||
19 | #include <linux/kobject.h> | |
20 | #include <linux/kobj_map.h> | |
21 | #include <linux/cdev.h> | |
58383af6 | 22 | #include <linux/mutex.h> |
1da177e4 LT |
23 | |
24 | #ifdef CONFIG_KMOD | |
25 | #include <linux/kmod.h> | |
26 | #endif | |
27 | ||
28 | static struct kobj_map *cdev_map; | |
29 | ||
1d4d5b32 | 30 | #define MAX_PROBE_HASH 255 /* random */ |
1da177e4 | 31 | |
58383af6 | 32 | static DEFINE_MUTEX(chrdevs_lock); |
1da177e4 LT |
33 | |
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 LT |
40 | struct file_operations *fops; |
41 | struct cdev *cdev; /* will die */ | |
42 | } *chrdevs[MAX_PROBE_HASH]; | |
43 | ||
44 | /* index in the above */ | |
45 | static inline int major_to_index(int major) | |
46 | { | |
47 | return major % MAX_PROBE_HASH; | |
48 | } | |
49 | ||
7170be5f NH |
50 | struct chrdev_info { |
51 | int index; | |
1da177e4 | 52 | struct char_device_struct *cd; |
7170be5f NH |
53 | }; |
54 | ||
55 | void *get_next_chrdev(void *dev) | |
56 | { | |
57 | struct chrdev_info *info; | |
58 | ||
59 | if (dev == NULL) { | |
60 | info = kmalloc(sizeof(*info), GFP_KERNEL); | |
61 | if (!info) | |
62 | goto out; | |
63 | info->index=0; | |
64 | info->cd = chrdevs[info->index]; | |
65 | if (info->cd) | |
66 | goto out; | |
67 | } else { | |
68 | info = dev; | |
69 | } | |
70 | ||
71 | while (info->index < ARRAY_SIZE(chrdevs)) { | |
72 | if (info->cd) | |
73 | info->cd = info->cd->next; | |
74 | if (info->cd) | |
75 | goto out; | |
76 | /* | |
77 | * No devices on this chain, move to the next | |
78 | */ | |
79 | info->index++; | |
80 | info->cd = (info->index < ARRAY_SIZE(chrdevs)) ? | |
81 | chrdevs[info->index] : NULL; | |
82 | if (info->cd) | |
83 | goto out; | |
84 | } | |
1da177e4 | 85 | |
7170be5f NH |
86 | out: |
87 | return info; | |
88 | } | |
1da177e4 | 89 | |
7170be5f NH |
90 | void *acquire_chrdev_list(void) |
91 | { | |
58383af6 | 92 | mutex_lock(&chrdevs_lock); |
7170be5f NH |
93 | return get_next_chrdev(NULL); |
94 | } | |
95 | ||
96 | void release_chrdev_list(void *dev) | |
97 | { | |
58383af6 | 98 | mutex_unlock(&chrdevs_lock); |
7170be5f NH |
99 | kfree(dev); |
100 | } | |
101 | ||
102 | ||
103 | int count_chrdev_list(void) | |
104 | { | |
105 | struct char_device_struct *cd; | |
106 | int i, count; | |
107 | ||
108 | count = 0; | |
109 | ||
1da177e4 | 110 | for (i = 0; i < ARRAY_SIZE(chrdevs) ; i++) { |
7170be5f NH |
111 | for (cd = chrdevs[i]; cd; cd = cd->next) |
112 | count++; | |
1da177e4 | 113 | } |
1da177e4 | 114 | |
7170be5f NH |
115 | return count; |
116 | } | |
117 | ||
118 | int get_chrdev_info(void *dev, int *major, char **name) | |
119 | { | |
120 | struct chrdev_info *info = dev; | |
121 | ||
122 | if (info->cd == NULL) | |
123 | return 1; | |
124 | ||
125 | *major = info->cd->major; | |
126 | *name = info->cd->name; | |
127 | return 0; | |
1da177e4 LT |
128 | } |
129 | ||
130 | /* | |
131 | * Register a single major with a specified minor range. | |
132 | * | |
133 | * If major == 0 this functions will dynamically allocate a major and return | |
134 | * its number. | |
135 | * | |
136 | * If major > 0 this function will attempt to reserve the passed range of | |
137 | * minors and will return zero on success. | |
138 | * | |
139 | * Returns a -ve errno on failure. | |
140 | */ | |
141 | static struct char_device_struct * | |
142 | __register_chrdev_region(unsigned int major, unsigned int baseminor, | |
143 | int minorct, const char *name) | |
144 | { | |
145 | struct char_device_struct *cd, **cp; | |
146 | int ret = 0; | |
147 | int i; | |
148 | ||
11b0b5ab | 149 | cd = kzalloc(sizeof(struct char_device_struct), GFP_KERNEL); |
1da177e4 LT |
150 | if (cd == NULL) |
151 | return ERR_PTR(-ENOMEM); | |
152 | ||
58383af6 | 153 | mutex_lock(&chrdevs_lock); |
1da177e4 LT |
154 | |
155 | /* temporary */ | |
156 | if (major == 0) { | |
157 | for (i = ARRAY_SIZE(chrdevs)-1; i > 0; i--) { | |
158 | if (chrdevs[i] == NULL) | |
159 | break; | |
160 | } | |
161 | ||
162 | if (i == 0) { | |
163 | ret = -EBUSY; | |
164 | goto out; | |
165 | } | |
166 | major = i; | |
167 | ret = major; | |
168 | } | |
169 | ||
170 | cd->major = major; | |
171 | cd->baseminor = baseminor; | |
172 | cd->minorct = minorct; | |
7170be5f | 173 | strncpy(cd->name,name, 64); |
1da177e4 LT |
174 | |
175 | i = major_to_index(major); | |
176 | ||
177 | for (cp = &chrdevs[i]; *cp; cp = &(*cp)->next) | |
178 | if ((*cp)->major > major || | |
179 | ((*cp)->major == major && (*cp)->baseminor >= baseminor)) | |
180 | break; | |
181 | if (*cp && (*cp)->major == major && | |
182 | (*cp)->baseminor < baseminor + minorct) { | |
183 | ret = -EBUSY; | |
184 | goto out; | |
185 | } | |
186 | cd->next = *cp; | |
187 | *cp = cd; | |
58383af6 | 188 | mutex_unlock(&chrdevs_lock); |
1da177e4 LT |
189 | return cd; |
190 | out: | |
58383af6 | 191 | mutex_unlock(&chrdevs_lock); |
1da177e4 LT |
192 | kfree(cd); |
193 | return ERR_PTR(ret); | |
194 | } | |
195 | ||
196 | static struct char_device_struct * | |
197 | __unregister_chrdev_region(unsigned major, unsigned baseminor, int minorct) | |
198 | { | |
199 | struct char_device_struct *cd = NULL, **cp; | |
200 | int i = major_to_index(major); | |
201 | ||
58383af6 | 202 | mutex_lock(&chrdevs_lock); |
1da177e4 LT |
203 | for (cp = &chrdevs[i]; *cp; cp = &(*cp)->next) |
204 | if ((*cp)->major == major && | |
205 | (*cp)->baseminor == baseminor && | |
206 | (*cp)->minorct == minorct) | |
207 | break; | |
208 | if (*cp) { | |
209 | cd = *cp; | |
210 | *cp = cd->next; | |
211 | } | |
58383af6 | 212 | mutex_unlock(&chrdevs_lock); |
1da177e4 LT |
213 | return cd; |
214 | } | |
215 | ||
216 | int register_chrdev_region(dev_t from, unsigned count, const char *name) | |
217 | { | |
218 | struct char_device_struct *cd; | |
219 | dev_t to = from + count; | |
220 | dev_t n, next; | |
221 | ||
222 | for (n = from; n < to; n = next) { | |
223 | next = MKDEV(MAJOR(n)+1, 0); | |
224 | if (next > to) | |
225 | next = to; | |
226 | cd = __register_chrdev_region(MAJOR(n), MINOR(n), | |
227 | next - n, name); | |
228 | if (IS_ERR(cd)) | |
229 | goto fail; | |
230 | } | |
231 | return 0; | |
232 | fail: | |
233 | to = n; | |
234 | for (n = from; n < to; n = next) { | |
235 | next = MKDEV(MAJOR(n)+1, 0); | |
236 | kfree(__unregister_chrdev_region(MAJOR(n), MINOR(n), next - n)); | |
237 | } | |
238 | return PTR_ERR(cd); | |
239 | } | |
240 | ||
241 | int alloc_chrdev_region(dev_t *dev, unsigned baseminor, unsigned count, | |
242 | const char *name) | |
243 | { | |
244 | struct char_device_struct *cd; | |
245 | cd = __register_chrdev_region(0, baseminor, count, name); | |
246 | if (IS_ERR(cd)) | |
247 | return PTR_ERR(cd); | |
248 | *dev = MKDEV(cd->major, cd->baseminor); | |
249 | return 0; | |
250 | } | |
251 | ||
252 | int register_chrdev(unsigned int major, const char *name, | |
99ac48f5 | 253 | const struct file_operations *fops) |
1da177e4 LT |
254 | { |
255 | struct char_device_struct *cd; | |
256 | struct cdev *cdev; | |
257 | char *s; | |
258 | int err = -ENOMEM; | |
259 | ||
260 | cd = __register_chrdev_region(major, 0, 256, name); | |
261 | if (IS_ERR(cd)) | |
262 | return PTR_ERR(cd); | |
263 | ||
264 | cdev = cdev_alloc(); | |
265 | if (!cdev) | |
266 | goto out2; | |
267 | ||
268 | cdev->owner = fops->owner; | |
269 | cdev->ops = fops; | |
270 | kobject_set_name(&cdev->kobj, "%s", name); | |
271 | for (s = strchr(kobject_name(&cdev->kobj),'/'); s; s = strchr(s, '/')) | |
272 | *s = '!'; | |
273 | ||
274 | err = cdev_add(cdev, MKDEV(cd->major, 0), 256); | |
275 | if (err) | |
276 | goto out; | |
277 | ||
278 | cd->cdev = cdev; | |
279 | ||
280 | return major ? 0 : cd->major; | |
281 | out: | |
282 | kobject_put(&cdev->kobj); | |
283 | out2: | |
284 | kfree(__unregister_chrdev_region(cd->major, 0, 256)); | |
285 | return err; | |
286 | } | |
287 | ||
288 | void unregister_chrdev_region(dev_t from, unsigned count) | |
289 | { | |
290 | dev_t to = from + count; | |
291 | dev_t n, next; | |
292 | ||
293 | for (n = from; n < to; n = next) { | |
294 | next = MKDEV(MAJOR(n)+1, 0); | |
295 | if (next > to) | |
296 | next = to; | |
297 | kfree(__unregister_chrdev_region(MAJOR(n), MINOR(n), next - n)); | |
298 | } | |
299 | } | |
300 | ||
301 | int unregister_chrdev(unsigned int major, const char *name) | |
302 | { | |
303 | struct char_device_struct *cd; | |
304 | cd = __unregister_chrdev_region(major, 0, 256); | |
305 | if (cd && cd->cdev) | |
306 | cdev_del(cd->cdev); | |
307 | kfree(cd); | |
308 | return 0; | |
309 | } | |
310 | ||
311 | static DEFINE_SPINLOCK(cdev_lock); | |
312 | ||
313 | static struct kobject *cdev_get(struct cdev *p) | |
314 | { | |
315 | struct module *owner = p->owner; | |
316 | struct kobject *kobj; | |
317 | ||
318 | if (owner && !try_module_get(owner)) | |
319 | return NULL; | |
320 | kobj = kobject_get(&p->kobj); | |
321 | if (!kobj) | |
322 | module_put(owner); | |
323 | return kobj; | |
324 | } | |
325 | ||
326 | void cdev_put(struct cdev *p) | |
327 | { | |
328 | if (p) { | |
7da6844c | 329 | struct module *owner = p->owner; |
1da177e4 | 330 | kobject_put(&p->kobj); |
7da6844c | 331 | module_put(owner); |
1da177e4 LT |
332 | } |
333 | } | |
334 | ||
335 | /* | |
336 | * Called every time a character special file is opened | |
337 | */ | |
338 | int chrdev_open(struct inode * inode, struct file * filp) | |
339 | { | |
340 | struct cdev *p; | |
341 | struct cdev *new = NULL; | |
342 | int ret = 0; | |
343 | ||
344 | spin_lock(&cdev_lock); | |
345 | p = inode->i_cdev; | |
346 | if (!p) { | |
347 | struct kobject *kobj; | |
348 | int idx; | |
349 | spin_unlock(&cdev_lock); | |
350 | kobj = kobj_lookup(cdev_map, inode->i_rdev, &idx); | |
351 | if (!kobj) | |
352 | return -ENXIO; | |
353 | new = container_of(kobj, struct cdev, kobj); | |
354 | spin_lock(&cdev_lock); | |
355 | p = inode->i_cdev; | |
356 | if (!p) { | |
357 | inode->i_cdev = p = new; | |
358 | inode->i_cindex = idx; | |
359 | list_add(&inode->i_devices, &p->list); | |
360 | new = NULL; | |
361 | } else if (!cdev_get(p)) | |
362 | ret = -ENXIO; | |
363 | } else if (!cdev_get(p)) | |
364 | ret = -ENXIO; | |
365 | spin_unlock(&cdev_lock); | |
366 | cdev_put(new); | |
367 | if (ret) | |
368 | return ret; | |
369 | filp->f_op = fops_get(p->ops); | |
370 | if (!filp->f_op) { | |
371 | cdev_put(p); | |
372 | return -ENXIO; | |
373 | } | |
374 | if (filp->f_op->open) { | |
375 | lock_kernel(); | |
376 | ret = filp->f_op->open(inode,filp); | |
377 | unlock_kernel(); | |
378 | } | |
379 | if (ret) | |
380 | cdev_put(p); | |
381 | return ret; | |
382 | } | |
383 | ||
384 | void cd_forget(struct inode *inode) | |
385 | { | |
386 | spin_lock(&cdev_lock); | |
387 | list_del_init(&inode->i_devices); | |
388 | inode->i_cdev = NULL; | |
389 | spin_unlock(&cdev_lock); | |
390 | } | |
391 | ||
75c96f85 | 392 | static void cdev_purge(struct cdev *cdev) |
1da177e4 LT |
393 | { |
394 | spin_lock(&cdev_lock); | |
395 | while (!list_empty(&cdev->list)) { | |
396 | struct inode *inode; | |
397 | inode = container_of(cdev->list.next, struct inode, i_devices); | |
398 | list_del_init(&inode->i_devices); | |
399 | inode->i_cdev = NULL; | |
400 | } | |
401 | spin_unlock(&cdev_lock); | |
402 | } | |
403 | ||
404 | /* | |
405 | * Dummy default file-operations: the only thing this does | |
406 | * is contain the open that then fills in the correct operations | |
407 | * depending on the special file... | |
408 | */ | |
4b6f5d20 | 409 | const struct file_operations def_chr_fops = { |
1da177e4 LT |
410 | .open = chrdev_open, |
411 | }; | |
412 | ||
413 | static struct kobject *exact_match(dev_t dev, int *part, void *data) | |
414 | { | |
415 | struct cdev *p = data; | |
416 | return &p->kobj; | |
417 | } | |
418 | ||
419 | static int exact_lock(dev_t dev, void *data) | |
420 | { | |
421 | struct cdev *p = data; | |
422 | return cdev_get(p) ? 0 : -1; | |
423 | } | |
424 | ||
425 | int cdev_add(struct cdev *p, dev_t dev, unsigned count) | |
426 | { | |
427 | p->dev = dev; | |
428 | p->count = count; | |
429 | return kobj_map(cdev_map, dev, count, NULL, exact_match, exact_lock, p); | |
430 | } | |
431 | ||
432 | static void cdev_unmap(dev_t dev, unsigned count) | |
433 | { | |
434 | kobj_unmap(cdev_map, dev, count); | |
435 | } | |
436 | ||
437 | void cdev_del(struct cdev *p) | |
438 | { | |
439 | cdev_unmap(p->dev, p->count); | |
440 | kobject_put(&p->kobj); | |
441 | } | |
442 | ||
443 | ||
444 | static void cdev_default_release(struct kobject *kobj) | |
445 | { | |
446 | struct cdev *p = container_of(kobj, struct cdev, kobj); | |
447 | cdev_purge(p); | |
448 | } | |
449 | ||
450 | static void cdev_dynamic_release(struct kobject *kobj) | |
451 | { | |
452 | struct cdev *p = container_of(kobj, struct cdev, kobj); | |
453 | cdev_purge(p); | |
454 | kfree(p); | |
455 | } | |
456 | ||
457 | static struct kobj_type ktype_cdev_default = { | |
458 | .release = cdev_default_release, | |
459 | }; | |
460 | ||
461 | static struct kobj_type ktype_cdev_dynamic = { | |
462 | .release = cdev_dynamic_release, | |
463 | }; | |
464 | ||
465 | struct cdev *cdev_alloc(void) | |
466 | { | |
11b0b5ab | 467 | struct cdev *p = kzalloc(sizeof(struct cdev), GFP_KERNEL); |
1da177e4 | 468 | if (p) { |
1da177e4 LT |
469 | p->kobj.ktype = &ktype_cdev_dynamic; |
470 | INIT_LIST_HEAD(&p->list); | |
471 | kobject_init(&p->kobj); | |
472 | } | |
473 | return p; | |
474 | } | |
475 | ||
99ac48f5 | 476 | void cdev_init(struct cdev *cdev, const struct file_operations *fops) |
1da177e4 LT |
477 | { |
478 | memset(cdev, 0, sizeof *cdev); | |
479 | INIT_LIST_HEAD(&cdev->list); | |
480 | cdev->kobj.ktype = &ktype_cdev_default; | |
481 | kobject_init(&cdev->kobj); | |
482 | cdev->ops = fops; | |
483 | } | |
484 | ||
485 | static struct kobject *base_probe(dev_t dev, int *part, void *data) | |
486 | { | |
487 | if (request_module("char-major-%d-%d", MAJOR(dev), MINOR(dev)) > 0) | |
488 | /* Make old-style 2.4 aliases work */ | |
489 | request_module("char-major-%d", MAJOR(dev)); | |
490 | return NULL; | |
491 | } | |
492 | ||
493 | void __init chrdev_init(void) | |
494 | { | |
495 | cdev_map = kobj_map_init(base_probe, &chrdevs_lock); | |
496 | } | |
497 | ||
498 | ||
499 | /* Let modules do char dev stuff */ | |
500 | EXPORT_SYMBOL(register_chrdev_region); | |
501 | EXPORT_SYMBOL(unregister_chrdev_region); | |
502 | EXPORT_SYMBOL(alloc_chrdev_region); | |
503 | EXPORT_SYMBOL(cdev_init); | |
504 | EXPORT_SYMBOL(cdev_alloc); | |
505 | EXPORT_SYMBOL(cdev_del); | |
506 | EXPORT_SYMBOL(cdev_add); | |
507 | EXPORT_SYMBOL(register_chrdev); | |
508 | EXPORT_SYMBOL(unregister_chrdev); |