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> | |
22 | ||
23 | #ifdef CONFIG_KMOD | |
24 | #include <linux/kmod.h> | |
25 | #endif | |
26 | ||
27 | static struct kobj_map *cdev_map; | |
28 | ||
1d4d5b32 | 29 | #define MAX_PROBE_HASH 255 /* random */ |
1da177e4 LT |
30 | |
31 | static DECLARE_MUTEX(chrdevs_lock); | |
32 | ||
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 LT |
39 | struct file_operations *fops; |
40 | struct cdev *cdev; /* will die */ | |
41 | } *chrdevs[MAX_PROBE_HASH]; | |
42 | ||
43 | /* index in the above */ | |
44 | static inline int major_to_index(int major) | |
45 | { | |
46 | return major % MAX_PROBE_HASH; | |
47 | } | |
48 | ||
7170be5f NH |
49 | struct chrdev_info { |
50 | int index; | |
1da177e4 | 51 | struct char_device_struct *cd; |
7170be5f NH |
52 | }; |
53 | ||
54 | void *get_next_chrdev(void *dev) | |
55 | { | |
56 | struct chrdev_info *info; | |
57 | ||
58 | if (dev == NULL) { | |
59 | info = kmalloc(sizeof(*info), GFP_KERNEL); | |
60 | if (!info) | |
61 | goto out; | |
62 | info->index=0; | |
63 | info->cd = chrdevs[info->index]; | |
64 | if (info->cd) | |
65 | goto out; | |
66 | } else { | |
67 | info = dev; | |
68 | } | |
69 | ||
70 | while (info->index < ARRAY_SIZE(chrdevs)) { | |
71 | if (info->cd) | |
72 | info->cd = info->cd->next; | |
73 | if (info->cd) | |
74 | goto out; | |
75 | /* | |
76 | * No devices on this chain, move to the next | |
77 | */ | |
78 | info->index++; | |
79 | info->cd = (info->index < ARRAY_SIZE(chrdevs)) ? | |
80 | chrdevs[info->index] : NULL; | |
81 | if (info->cd) | |
82 | goto out; | |
83 | } | |
1da177e4 | 84 | |
7170be5f NH |
85 | out: |
86 | return info; | |
87 | } | |
1da177e4 | 88 | |
7170be5f NH |
89 | void *acquire_chrdev_list(void) |
90 | { | |
1da177e4 | 91 | down(&chrdevs_lock); |
7170be5f NH |
92 | return get_next_chrdev(NULL); |
93 | } | |
94 | ||
95 | void release_chrdev_list(void *dev) | |
96 | { | |
97 | up(&chrdevs_lock); | |
98 | kfree(dev); | |
99 | } | |
100 | ||
101 | ||
102 | int count_chrdev_list(void) | |
103 | { | |
104 | struct char_device_struct *cd; | |
105 | int i, count; | |
106 | ||
107 | count = 0; | |
108 | ||
1da177e4 | 109 | for (i = 0; i < ARRAY_SIZE(chrdevs) ; i++) { |
7170be5f NH |
110 | for (cd = chrdevs[i]; cd; cd = cd->next) |
111 | count++; | |
1da177e4 | 112 | } |
1da177e4 | 113 | |
7170be5f NH |
114 | return count; |
115 | } | |
116 | ||
117 | int get_chrdev_info(void *dev, int *major, char **name) | |
118 | { | |
119 | struct chrdev_info *info = dev; | |
120 | ||
121 | if (info->cd == NULL) | |
122 | return 1; | |
123 | ||
124 | *major = info->cd->major; | |
125 | *name = info->cd->name; | |
126 | return 0; | |
1da177e4 LT |
127 | } |
128 | ||
129 | /* | |
130 | * Register a single major with a specified minor range. | |
131 | * | |
132 | * If major == 0 this functions will dynamically allocate a major and return | |
133 | * its number. | |
134 | * | |
135 | * If major > 0 this function will attempt to reserve the passed range of | |
136 | * minors and will return zero on success. | |
137 | * | |
138 | * Returns a -ve errno on failure. | |
139 | */ | |
140 | static struct char_device_struct * | |
141 | __register_chrdev_region(unsigned int major, unsigned int baseminor, | |
142 | int minorct, const char *name) | |
143 | { | |
144 | struct char_device_struct *cd, **cp; | |
145 | int ret = 0; | |
146 | int i; | |
147 | ||
148 | cd = kmalloc(sizeof(struct char_device_struct), GFP_KERNEL); | |
149 | if (cd == NULL) | |
150 | return ERR_PTR(-ENOMEM); | |
151 | ||
152 | memset(cd, 0, sizeof(struct char_device_struct)); | |
153 | ||
154 | down(&chrdevs_lock); | |
155 | ||
156 | /* temporary */ | |
157 | if (major == 0) { | |
158 | for (i = ARRAY_SIZE(chrdevs)-1; i > 0; i--) { | |
159 | if (chrdevs[i] == NULL) | |
160 | break; | |
161 | } | |
162 | ||
163 | if (i == 0) { | |
164 | ret = -EBUSY; | |
165 | goto out; | |
166 | } | |
167 | major = i; | |
168 | ret = major; | |
169 | } | |
170 | ||
171 | cd->major = major; | |
172 | cd->baseminor = baseminor; | |
173 | cd->minorct = minorct; | |
7170be5f | 174 | strncpy(cd->name,name, 64); |
1da177e4 LT |
175 | |
176 | i = major_to_index(major); | |
177 | ||
178 | for (cp = &chrdevs[i]; *cp; cp = &(*cp)->next) | |
179 | if ((*cp)->major > major || | |
180 | ((*cp)->major == major && (*cp)->baseminor >= baseminor)) | |
181 | break; | |
182 | if (*cp && (*cp)->major == major && | |
183 | (*cp)->baseminor < baseminor + minorct) { | |
184 | ret = -EBUSY; | |
185 | goto out; | |
186 | } | |
187 | cd->next = *cp; | |
188 | *cp = cd; | |
189 | up(&chrdevs_lock); | |
190 | return cd; | |
191 | out: | |
192 | up(&chrdevs_lock); | |
193 | kfree(cd); | |
194 | return ERR_PTR(ret); | |
195 | } | |
196 | ||
197 | static struct char_device_struct * | |
198 | __unregister_chrdev_region(unsigned major, unsigned baseminor, int minorct) | |
199 | { | |
200 | struct char_device_struct *cd = NULL, **cp; | |
201 | int i = major_to_index(major); | |
202 | ||
8d451687 | 203 | down(&chrdevs_lock); |
1da177e4 LT |
204 | for (cp = &chrdevs[i]; *cp; cp = &(*cp)->next) |
205 | if ((*cp)->major == major && | |
206 | (*cp)->baseminor == baseminor && | |
207 | (*cp)->minorct == minorct) | |
208 | break; | |
209 | if (*cp) { | |
210 | cd = *cp; | |
211 | *cp = cd->next; | |
212 | } | |
213 | up(&chrdevs_lock); | |
214 | return cd; | |
215 | } | |
216 | ||
217 | int register_chrdev_region(dev_t from, unsigned count, const char *name) | |
218 | { | |
219 | struct char_device_struct *cd; | |
220 | dev_t to = from + count; | |
221 | dev_t n, next; | |
222 | ||
223 | for (n = from; n < to; n = next) { | |
224 | next = MKDEV(MAJOR(n)+1, 0); | |
225 | if (next > to) | |
226 | next = to; | |
227 | cd = __register_chrdev_region(MAJOR(n), MINOR(n), | |
228 | next - n, name); | |
229 | if (IS_ERR(cd)) | |
230 | goto fail; | |
231 | } | |
232 | return 0; | |
233 | fail: | |
234 | to = n; | |
235 | for (n = from; n < to; n = next) { | |
236 | next = MKDEV(MAJOR(n)+1, 0); | |
237 | kfree(__unregister_chrdev_region(MAJOR(n), MINOR(n), next - n)); | |
238 | } | |
239 | return PTR_ERR(cd); | |
240 | } | |
241 | ||
242 | int alloc_chrdev_region(dev_t *dev, unsigned baseminor, unsigned count, | |
243 | const char *name) | |
244 | { | |
245 | struct char_device_struct *cd; | |
246 | cd = __register_chrdev_region(0, baseminor, count, name); | |
247 | if (IS_ERR(cd)) | |
248 | return PTR_ERR(cd); | |
249 | *dev = MKDEV(cd->major, cd->baseminor); | |
250 | return 0; | |
251 | } | |
252 | ||
253 | int register_chrdev(unsigned int major, const char *name, | |
254 | struct file_operations *fops) | |
255 | { | |
256 | struct char_device_struct *cd; | |
257 | struct cdev *cdev; | |
258 | char *s; | |
259 | int err = -ENOMEM; | |
260 | ||
261 | cd = __register_chrdev_region(major, 0, 256, name); | |
262 | if (IS_ERR(cd)) | |
263 | return PTR_ERR(cd); | |
264 | ||
265 | cdev = cdev_alloc(); | |
266 | if (!cdev) | |
267 | goto out2; | |
268 | ||
269 | cdev->owner = fops->owner; | |
270 | cdev->ops = fops; | |
271 | kobject_set_name(&cdev->kobj, "%s", name); | |
272 | for (s = strchr(kobject_name(&cdev->kobj),'/'); s; s = strchr(s, '/')) | |
273 | *s = '!'; | |
274 | ||
275 | err = cdev_add(cdev, MKDEV(cd->major, 0), 256); | |
276 | if (err) | |
277 | goto out; | |
278 | ||
279 | cd->cdev = cdev; | |
280 | ||
281 | return major ? 0 : cd->major; | |
282 | out: | |
283 | kobject_put(&cdev->kobj); | |
284 | out2: | |
285 | kfree(__unregister_chrdev_region(cd->major, 0, 256)); | |
286 | return err; | |
287 | } | |
288 | ||
289 | void unregister_chrdev_region(dev_t from, unsigned count) | |
290 | { | |
291 | dev_t to = from + count; | |
292 | dev_t n, next; | |
293 | ||
294 | for (n = from; n < to; n = next) { | |
295 | next = MKDEV(MAJOR(n)+1, 0); | |
296 | if (next > to) | |
297 | next = to; | |
298 | kfree(__unregister_chrdev_region(MAJOR(n), MINOR(n), next - n)); | |
299 | } | |
300 | } | |
301 | ||
302 | int unregister_chrdev(unsigned int major, const char *name) | |
303 | { | |
304 | struct char_device_struct *cd; | |
305 | cd = __unregister_chrdev_region(major, 0, 256); | |
306 | if (cd && cd->cdev) | |
307 | cdev_del(cd->cdev); | |
308 | kfree(cd); | |
309 | return 0; | |
310 | } | |
311 | ||
312 | static DEFINE_SPINLOCK(cdev_lock); | |
313 | ||
314 | static struct kobject *cdev_get(struct cdev *p) | |
315 | { | |
316 | struct module *owner = p->owner; | |
317 | struct kobject *kobj; | |
318 | ||
319 | if (owner && !try_module_get(owner)) | |
320 | return NULL; | |
321 | kobj = kobject_get(&p->kobj); | |
322 | if (!kobj) | |
323 | module_put(owner); | |
324 | return kobj; | |
325 | } | |
326 | ||
327 | void cdev_put(struct cdev *p) | |
328 | { | |
329 | if (p) { | |
7da6844c | 330 | struct module *owner = p->owner; |
1da177e4 | 331 | kobject_put(&p->kobj); |
7da6844c | 332 | module_put(owner); |
1da177e4 LT |
333 | } |
334 | } | |
335 | ||
336 | /* | |
337 | * Called every time a character special file is opened | |
338 | */ | |
339 | int chrdev_open(struct inode * inode, struct file * filp) | |
340 | { | |
341 | struct cdev *p; | |
342 | struct cdev *new = NULL; | |
343 | int ret = 0; | |
344 | ||
345 | spin_lock(&cdev_lock); | |
346 | p = inode->i_cdev; | |
347 | if (!p) { | |
348 | struct kobject *kobj; | |
349 | int idx; | |
350 | spin_unlock(&cdev_lock); | |
351 | kobj = kobj_lookup(cdev_map, inode->i_rdev, &idx); | |
352 | if (!kobj) | |
353 | return -ENXIO; | |
354 | new = container_of(kobj, struct cdev, kobj); | |
355 | spin_lock(&cdev_lock); | |
356 | p = inode->i_cdev; | |
357 | if (!p) { | |
358 | inode->i_cdev = p = new; | |
359 | inode->i_cindex = idx; | |
360 | list_add(&inode->i_devices, &p->list); | |
361 | new = NULL; | |
362 | } else if (!cdev_get(p)) | |
363 | ret = -ENXIO; | |
364 | } else if (!cdev_get(p)) | |
365 | ret = -ENXIO; | |
366 | spin_unlock(&cdev_lock); | |
367 | cdev_put(new); | |
368 | if (ret) | |
369 | return ret; | |
370 | filp->f_op = fops_get(p->ops); | |
371 | if (!filp->f_op) { | |
372 | cdev_put(p); | |
373 | return -ENXIO; | |
374 | } | |
375 | if (filp->f_op->open) { | |
376 | lock_kernel(); | |
377 | ret = filp->f_op->open(inode,filp); | |
378 | unlock_kernel(); | |
379 | } | |
380 | if (ret) | |
381 | cdev_put(p); | |
382 | return ret; | |
383 | } | |
384 | ||
385 | void cd_forget(struct inode *inode) | |
386 | { | |
387 | spin_lock(&cdev_lock); | |
388 | list_del_init(&inode->i_devices); | |
389 | inode->i_cdev = NULL; | |
390 | spin_unlock(&cdev_lock); | |
391 | } | |
392 | ||
75c96f85 | 393 | static void cdev_purge(struct cdev *cdev) |
1da177e4 LT |
394 | { |
395 | spin_lock(&cdev_lock); | |
396 | while (!list_empty(&cdev->list)) { | |
397 | struct inode *inode; | |
398 | inode = container_of(cdev->list.next, struct inode, i_devices); | |
399 | list_del_init(&inode->i_devices); | |
400 | inode->i_cdev = NULL; | |
401 | } | |
402 | spin_unlock(&cdev_lock); | |
403 | } | |
404 | ||
405 | /* | |
406 | * Dummy default file-operations: the only thing this does | |
407 | * is contain the open that then fills in the correct operations | |
408 | * depending on the special file... | |
409 | */ | |
410 | struct file_operations def_chr_fops = { | |
411 | .open = chrdev_open, | |
412 | }; | |
413 | ||
414 | static struct kobject *exact_match(dev_t dev, int *part, void *data) | |
415 | { | |
416 | struct cdev *p = data; | |
417 | return &p->kobj; | |
418 | } | |
419 | ||
420 | static int exact_lock(dev_t dev, void *data) | |
421 | { | |
422 | struct cdev *p = data; | |
423 | return cdev_get(p) ? 0 : -1; | |
424 | } | |
425 | ||
426 | int cdev_add(struct cdev *p, dev_t dev, unsigned count) | |
427 | { | |
428 | p->dev = dev; | |
429 | p->count = count; | |
430 | return kobj_map(cdev_map, dev, count, NULL, exact_match, exact_lock, p); | |
431 | } | |
432 | ||
433 | static void cdev_unmap(dev_t dev, unsigned count) | |
434 | { | |
435 | kobj_unmap(cdev_map, dev, count); | |
436 | } | |
437 | ||
438 | void cdev_del(struct cdev *p) | |
439 | { | |
440 | cdev_unmap(p->dev, p->count); | |
441 | kobject_put(&p->kobj); | |
442 | } | |
443 | ||
444 | ||
445 | static void cdev_default_release(struct kobject *kobj) | |
446 | { | |
447 | struct cdev *p = container_of(kobj, struct cdev, kobj); | |
448 | cdev_purge(p); | |
449 | } | |
450 | ||
451 | static void cdev_dynamic_release(struct kobject *kobj) | |
452 | { | |
453 | struct cdev *p = container_of(kobj, struct cdev, kobj); | |
454 | cdev_purge(p); | |
455 | kfree(p); | |
456 | } | |
457 | ||
458 | static struct kobj_type ktype_cdev_default = { | |
459 | .release = cdev_default_release, | |
460 | }; | |
461 | ||
462 | static struct kobj_type ktype_cdev_dynamic = { | |
463 | .release = cdev_dynamic_release, | |
464 | }; | |
465 | ||
466 | struct cdev *cdev_alloc(void) | |
467 | { | |
468 | struct cdev *p = kmalloc(sizeof(struct cdev), GFP_KERNEL); | |
469 | if (p) { | |
470 | memset(p, 0, sizeof(struct cdev)); | |
471 | p->kobj.ktype = &ktype_cdev_dynamic; | |
472 | INIT_LIST_HEAD(&p->list); | |
473 | kobject_init(&p->kobj); | |
474 | } | |
475 | return p; | |
476 | } | |
477 | ||
478 | void cdev_init(struct cdev *cdev, struct file_operations *fops) | |
479 | { | |
480 | memset(cdev, 0, sizeof *cdev); | |
481 | INIT_LIST_HEAD(&cdev->list); | |
482 | cdev->kobj.ktype = &ktype_cdev_default; | |
483 | kobject_init(&cdev->kobj); | |
484 | cdev->ops = fops; | |
485 | } | |
486 | ||
487 | static struct kobject *base_probe(dev_t dev, int *part, void *data) | |
488 | { | |
489 | if (request_module("char-major-%d-%d", MAJOR(dev), MINOR(dev)) > 0) | |
490 | /* Make old-style 2.4 aliases work */ | |
491 | request_module("char-major-%d", MAJOR(dev)); | |
492 | return NULL; | |
493 | } | |
494 | ||
495 | void __init chrdev_init(void) | |
496 | { | |
497 | cdev_map = kobj_map_init(base_probe, &chrdevs_lock); | |
498 | } | |
499 | ||
500 | ||
501 | /* Let modules do char dev stuff */ | |
502 | EXPORT_SYMBOL(register_chrdev_region); | |
503 | EXPORT_SYMBOL(unregister_chrdev_region); | |
504 | EXPORT_SYMBOL(alloc_chrdev_region); | |
505 | EXPORT_SYMBOL(cdev_init); | |
506 | EXPORT_SYMBOL(cdev_alloc); | |
507 | EXPORT_SYMBOL(cdev_del); | |
508 | EXPORT_SYMBOL(cdev_add); | |
509 | EXPORT_SYMBOL(register_chrdev); | |
510 | EXPORT_SYMBOL(unregister_chrdev); |