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> | |
9 | #include <linux/slab.h> | |
10 | #include <linux/string.h> | |
11 | ||
12 | #include <linux/major.h> | |
13 | #include <linux/errno.h> | |
14 | #include <linux/module.h> | |
15 | #include <linux/smp_lock.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> |
1da177e4 LT |
22 | |
23 | #ifdef CONFIG_KMOD | |
24 | #include <linux/kmod.h> | |
25 | #endif | |
26 | ||
27 | static struct kobj_map *cdev_map; | |
28 | ||
58383af6 | 29 | static DEFINE_MUTEX(chrdevs_lock); |
1da177e4 LT |
30 | |
31 | static struct char_device_struct { | |
32 | struct char_device_struct *next; | |
33 | unsigned int major; | |
34 | unsigned int baseminor; | |
35 | int minorct; | |
7170be5f | 36 | char name[64]; |
1da177e4 LT |
37 | struct file_operations *fops; |
38 | struct cdev *cdev; /* will die */ | |
68eef3b4 | 39 | } *chrdevs[CHRDEV_MAJOR_HASH_SIZE]; |
1da177e4 LT |
40 | |
41 | /* index in the above */ | |
42 | static inline int major_to_index(int major) | |
43 | { | |
68eef3b4 | 44 | return major % CHRDEV_MAJOR_HASH_SIZE; |
7170be5f NH |
45 | } |
46 | ||
68eef3b4 | 47 | #ifdef CONFIG_PROC_FS |
7170be5f | 48 | |
68eef3b4 | 49 | void chrdev_show(struct seq_file *f, off_t offset) |
7170be5f NH |
50 | { |
51 | struct char_device_struct *cd; | |
7170be5f | 52 | |
68eef3b4 JK |
53 | if (offset < CHRDEV_MAJOR_HASH_SIZE) { |
54 | mutex_lock(&chrdevs_lock); | |
55 | for (cd = chrdevs[offset]; cd; cd = cd->next) | |
56 | seq_printf(f, "%3d %s\n", cd->major, cd->name); | |
57 | mutex_unlock(&chrdevs_lock); | |
1da177e4 | 58 | } |
7170be5f NH |
59 | } |
60 | ||
68eef3b4 | 61 | #endif /* CONFIG_PROC_FS */ |
1da177e4 LT |
62 | |
63 | /* | |
64 | * Register a single major with a specified minor range. | |
65 | * | |
66 | * If major == 0 this functions will dynamically allocate a major and return | |
67 | * its number. | |
68 | * | |
69 | * If major > 0 this function will attempt to reserve the passed range of | |
70 | * minors and will return zero on success. | |
71 | * | |
72 | * Returns a -ve errno on failure. | |
73 | */ | |
74 | static struct char_device_struct * | |
75 | __register_chrdev_region(unsigned int major, unsigned int baseminor, | |
76 | int minorct, const char *name) | |
77 | { | |
78 | struct char_device_struct *cd, **cp; | |
79 | int ret = 0; | |
80 | int i; | |
81 | ||
11b0b5ab | 82 | cd = kzalloc(sizeof(struct char_device_struct), GFP_KERNEL); |
1da177e4 LT |
83 | if (cd == NULL) |
84 | return ERR_PTR(-ENOMEM); | |
85 | ||
58383af6 | 86 | mutex_lock(&chrdevs_lock); |
1da177e4 LT |
87 | |
88 | /* temporary */ | |
89 | if (major == 0) { | |
90 | for (i = ARRAY_SIZE(chrdevs)-1; i > 0; i--) { | |
91 | if (chrdevs[i] == NULL) | |
92 | break; | |
93 | } | |
94 | ||
95 | if (i == 0) { | |
96 | ret = -EBUSY; | |
97 | goto out; | |
98 | } | |
99 | major = i; | |
100 | ret = major; | |
101 | } | |
102 | ||
103 | cd->major = major; | |
104 | cd->baseminor = baseminor; | |
105 | cd->minorct = minorct; | |
7170be5f | 106 | strncpy(cd->name,name, 64); |
1da177e4 LT |
107 | |
108 | i = major_to_index(major); | |
109 | ||
110 | for (cp = &chrdevs[i]; *cp; cp = &(*cp)->next) | |
111 | if ((*cp)->major > major || | |
112 | ((*cp)->major == major && (*cp)->baseminor >= baseminor)) | |
113 | break; | |
114 | if (*cp && (*cp)->major == major && | |
115 | (*cp)->baseminor < baseminor + minorct) { | |
116 | ret = -EBUSY; | |
117 | goto out; | |
118 | } | |
119 | cd->next = *cp; | |
120 | *cp = cd; | |
58383af6 | 121 | mutex_unlock(&chrdevs_lock); |
1da177e4 LT |
122 | return cd; |
123 | out: | |
58383af6 | 124 | mutex_unlock(&chrdevs_lock); |
1da177e4 LT |
125 | kfree(cd); |
126 | return ERR_PTR(ret); | |
127 | } | |
128 | ||
129 | static struct char_device_struct * | |
130 | __unregister_chrdev_region(unsigned major, unsigned baseminor, int minorct) | |
131 | { | |
132 | struct char_device_struct *cd = NULL, **cp; | |
133 | int i = major_to_index(major); | |
134 | ||
58383af6 | 135 | mutex_lock(&chrdevs_lock); |
1da177e4 LT |
136 | for (cp = &chrdevs[i]; *cp; cp = &(*cp)->next) |
137 | if ((*cp)->major == major && | |
138 | (*cp)->baseminor == baseminor && | |
139 | (*cp)->minorct == minorct) | |
140 | break; | |
141 | if (*cp) { | |
142 | cd = *cp; | |
143 | *cp = cd->next; | |
144 | } | |
58383af6 | 145 | mutex_unlock(&chrdevs_lock); |
1da177e4 LT |
146 | return cd; |
147 | } | |
148 | ||
149 | int register_chrdev_region(dev_t from, unsigned count, const char *name) | |
150 | { | |
151 | struct char_device_struct *cd; | |
152 | dev_t to = from + count; | |
153 | dev_t n, next; | |
154 | ||
155 | for (n = from; n < to; n = next) { | |
156 | next = MKDEV(MAJOR(n)+1, 0); | |
157 | if (next > to) | |
158 | next = to; | |
159 | cd = __register_chrdev_region(MAJOR(n), MINOR(n), | |
160 | next - n, name); | |
161 | if (IS_ERR(cd)) | |
162 | goto fail; | |
163 | } | |
164 | return 0; | |
165 | fail: | |
166 | to = n; | |
167 | for (n = from; n < to; n = next) { | |
168 | next = MKDEV(MAJOR(n)+1, 0); | |
169 | kfree(__unregister_chrdev_region(MAJOR(n), MINOR(n), next - n)); | |
170 | } | |
171 | return PTR_ERR(cd); | |
172 | } | |
173 | ||
174 | int alloc_chrdev_region(dev_t *dev, unsigned baseminor, unsigned count, | |
175 | const char *name) | |
176 | { | |
177 | struct char_device_struct *cd; | |
178 | cd = __register_chrdev_region(0, baseminor, count, name); | |
179 | if (IS_ERR(cd)) | |
180 | return PTR_ERR(cd); | |
181 | *dev = MKDEV(cd->major, cd->baseminor); | |
182 | return 0; | |
183 | } | |
184 | ||
d247e2c6 REB |
185 | /** |
186 | * register_chrdev() - Register a major number for character devices. | |
187 | * @major: major device number or 0 for dynamic allocation | |
188 | * @name: name of this range of devices | |
189 | * @fops: file operations associated with this devices | |
190 | * | |
191 | * If @major == 0 this functions will dynamically allocate a major and return | |
192 | * its number. | |
193 | * | |
194 | * If @major > 0 this function will attempt to reserve a device with the given | |
195 | * major number and will return zero on success. | |
196 | * | |
197 | * Returns a -ve errno on failure. | |
198 | * | |
199 | * The name of this device has nothing to do with the name of the device in | |
200 | * /dev. It only helps to keep track of the different owners of devices. If | |
201 | * your module name has only one type of devices it's ok to use e.g. the name | |
202 | * of the module here. | |
203 | * | |
204 | * This function registers a range of 256 minor numbers. The first minor number | |
205 | * is 0. | |
206 | */ | |
1da177e4 | 207 | int register_chrdev(unsigned int major, const char *name, |
99ac48f5 | 208 | const struct file_operations *fops) |
1da177e4 LT |
209 | { |
210 | struct char_device_struct *cd; | |
211 | struct cdev *cdev; | |
212 | char *s; | |
213 | int err = -ENOMEM; | |
214 | ||
215 | cd = __register_chrdev_region(major, 0, 256, name); | |
216 | if (IS_ERR(cd)) | |
217 | return PTR_ERR(cd); | |
218 | ||
219 | cdev = cdev_alloc(); | |
220 | if (!cdev) | |
221 | goto out2; | |
222 | ||
223 | cdev->owner = fops->owner; | |
224 | cdev->ops = fops; | |
225 | kobject_set_name(&cdev->kobj, "%s", name); | |
226 | for (s = strchr(kobject_name(&cdev->kobj),'/'); s; s = strchr(s, '/')) | |
227 | *s = '!'; | |
228 | ||
229 | err = cdev_add(cdev, MKDEV(cd->major, 0), 256); | |
230 | if (err) | |
231 | goto out; | |
232 | ||
233 | cd->cdev = cdev; | |
234 | ||
235 | return major ? 0 : cd->major; | |
236 | out: | |
237 | kobject_put(&cdev->kobj); | |
238 | out2: | |
239 | kfree(__unregister_chrdev_region(cd->major, 0, 256)); | |
240 | return err; | |
241 | } | |
242 | ||
243 | void unregister_chrdev_region(dev_t from, unsigned count) | |
244 | { | |
245 | dev_t to = from + count; | |
246 | dev_t n, next; | |
247 | ||
248 | for (n = from; n < to; n = next) { | |
249 | next = MKDEV(MAJOR(n)+1, 0); | |
250 | if (next > to) | |
251 | next = to; | |
252 | kfree(__unregister_chrdev_region(MAJOR(n), MINOR(n), next - n)); | |
253 | } | |
254 | } | |
255 | ||
256 | int unregister_chrdev(unsigned int major, const char *name) | |
257 | { | |
258 | struct char_device_struct *cd; | |
259 | cd = __unregister_chrdev_region(major, 0, 256); | |
260 | if (cd && cd->cdev) | |
261 | cdev_del(cd->cdev); | |
262 | kfree(cd); | |
263 | return 0; | |
264 | } | |
265 | ||
266 | static DEFINE_SPINLOCK(cdev_lock); | |
267 | ||
268 | static struct kobject *cdev_get(struct cdev *p) | |
269 | { | |
270 | struct module *owner = p->owner; | |
271 | struct kobject *kobj; | |
272 | ||
273 | if (owner && !try_module_get(owner)) | |
274 | return NULL; | |
275 | kobj = kobject_get(&p->kobj); | |
276 | if (!kobj) | |
277 | module_put(owner); | |
278 | return kobj; | |
279 | } | |
280 | ||
281 | void cdev_put(struct cdev *p) | |
282 | { | |
283 | if (p) { | |
7da6844c | 284 | struct module *owner = p->owner; |
1da177e4 | 285 | kobject_put(&p->kobj); |
7da6844c | 286 | module_put(owner); |
1da177e4 LT |
287 | } |
288 | } | |
289 | ||
290 | /* | |
291 | * Called every time a character special file is opened | |
292 | */ | |
293 | int chrdev_open(struct inode * inode, struct file * filp) | |
294 | { | |
295 | struct cdev *p; | |
296 | struct cdev *new = NULL; | |
297 | int ret = 0; | |
298 | ||
299 | spin_lock(&cdev_lock); | |
300 | p = inode->i_cdev; | |
301 | if (!p) { | |
302 | struct kobject *kobj; | |
303 | int idx; | |
304 | spin_unlock(&cdev_lock); | |
305 | kobj = kobj_lookup(cdev_map, inode->i_rdev, &idx); | |
306 | if (!kobj) | |
307 | return -ENXIO; | |
308 | new = container_of(kobj, struct cdev, kobj); | |
309 | spin_lock(&cdev_lock); | |
310 | p = inode->i_cdev; | |
311 | if (!p) { | |
312 | inode->i_cdev = p = new; | |
313 | inode->i_cindex = idx; | |
314 | list_add(&inode->i_devices, &p->list); | |
315 | new = NULL; | |
316 | } else if (!cdev_get(p)) | |
317 | ret = -ENXIO; | |
318 | } else if (!cdev_get(p)) | |
319 | ret = -ENXIO; | |
320 | spin_unlock(&cdev_lock); | |
321 | cdev_put(new); | |
322 | if (ret) | |
323 | return ret; | |
324 | filp->f_op = fops_get(p->ops); | |
325 | if (!filp->f_op) { | |
326 | cdev_put(p); | |
327 | return -ENXIO; | |
328 | } | |
329 | if (filp->f_op->open) { | |
330 | lock_kernel(); | |
331 | ret = filp->f_op->open(inode,filp); | |
332 | unlock_kernel(); | |
333 | } | |
334 | if (ret) | |
335 | cdev_put(p); | |
336 | return ret; | |
337 | } | |
338 | ||
339 | void cd_forget(struct inode *inode) | |
340 | { | |
341 | spin_lock(&cdev_lock); | |
342 | list_del_init(&inode->i_devices); | |
343 | inode->i_cdev = NULL; | |
344 | spin_unlock(&cdev_lock); | |
345 | } | |
346 | ||
75c96f85 | 347 | static void cdev_purge(struct cdev *cdev) |
1da177e4 LT |
348 | { |
349 | spin_lock(&cdev_lock); | |
350 | while (!list_empty(&cdev->list)) { | |
351 | struct inode *inode; | |
352 | inode = container_of(cdev->list.next, struct inode, i_devices); | |
353 | list_del_init(&inode->i_devices); | |
354 | inode->i_cdev = NULL; | |
355 | } | |
356 | spin_unlock(&cdev_lock); | |
357 | } | |
358 | ||
359 | /* | |
360 | * Dummy default file-operations: the only thing this does | |
361 | * is contain the open that then fills in the correct operations | |
362 | * depending on the special file... | |
363 | */ | |
4b6f5d20 | 364 | const struct file_operations def_chr_fops = { |
1da177e4 LT |
365 | .open = chrdev_open, |
366 | }; | |
367 | ||
368 | static struct kobject *exact_match(dev_t dev, int *part, void *data) | |
369 | { | |
370 | struct cdev *p = data; | |
371 | return &p->kobj; | |
372 | } | |
373 | ||
374 | static int exact_lock(dev_t dev, void *data) | |
375 | { | |
376 | struct cdev *p = data; | |
377 | return cdev_get(p) ? 0 : -1; | |
378 | } | |
379 | ||
380 | int cdev_add(struct cdev *p, dev_t dev, unsigned count) | |
381 | { | |
382 | p->dev = dev; | |
383 | p->count = count; | |
384 | return kobj_map(cdev_map, dev, count, NULL, exact_match, exact_lock, p); | |
385 | } | |
386 | ||
387 | static void cdev_unmap(dev_t dev, unsigned count) | |
388 | { | |
389 | kobj_unmap(cdev_map, dev, count); | |
390 | } | |
391 | ||
392 | void cdev_del(struct cdev *p) | |
393 | { | |
394 | cdev_unmap(p->dev, p->count); | |
395 | kobject_put(&p->kobj); | |
396 | } | |
397 | ||
398 | ||
399 | static void cdev_default_release(struct kobject *kobj) | |
400 | { | |
401 | struct cdev *p = container_of(kobj, struct cdev, kobj); | |
402 | cdev_purge(p); | |
403 | } | |
404 | ||
405 | static void cdev_dynamic_release(struct kobject *kobj) | |
406 | { | |
407 | struct cdev *p = container_of(kobj, struct cdev, kobj); | |
408 | cdev_purge(p); | |
409 | kfree(p); | |
410 | } | |
411 | ||
412 | static struct kobj_type ktype_cdev_default = { | |
413 | .release = cdev_default_release, | |
414 | }; | |
415 | ||
416 | static struct kobj_type ktype_cdev_dynamic = { | |
417 | .release = cdev_dynamic_release, | |
418 | }; | |
419 | ||
420 | struct cdev *cdev_alloc(void) | |
421 | { | |
11b0b5ab | 422 | struct cdev *p = kzalloc(sizeof(struct cdev), GFP_KERNEL); |
1da177e4 | 423 | if (p) { |
1da177e4 LT |
424 | p->kobj.ktype = &ktype_cdev_dynamic; |
425 | INIT_LIST_HEAD(&p->list); | |
426 | kobject_init(&p->kobj); | |
427 | } | |
428 | return p; | |
429 | } | |
430 | ||
99ac48f5 | 431 | void cdev_init(struct cdev *cdev, const struct file_operations *fops) |
1da177e4 LT |
432 | { |
433 | memset(cdev, 0, sizeof *cdev); | |
434 | INIT_LIST_HEAD(&cdev->list); | |
435 | cdev->kobj.ktype = &ktype_cdev_default; | |
436 | kobject_init(&cdev->kobj); | |
437 | cdev->ops = fops; | |
438 | } | |
439 | ||
440 | static struct kobject *base_probe(dev_t dev, int *part, void *data) | |
441 | { | |
442 | if (request_module("char-major-%d-%d", MAJOR(dev), MINOR(dev)) > 0) | |
443 | /* Make old-style 2.4 aliases work */ | |
444 | request_module("char-major-%d", MAJOR(dev)); | |
445 | return NULL; | |
446 | } | |
447 | ||
448 | void __init chrdev_init(void) | |
449 | { | |
450 | cdev_map = kobj_map_init(base_probe, &chrdevs_lock); | |
451 | } | |
452 | ||
453 | ||
454 | /* Let modules do char dev stuff */ | |
455 | EXPORT_SYMBOL(register_chrdev_region); | |
456 | EXPORT_SYMBOL(unregister_chrdev_region); | |
457 | EXPORT_SYMBOL(alloc_chrdev_region); | |
458 | EXPORT_SYMBOL(cdev_init); | |
459 | EXPORT_SYMBOL(cdev_alloc); | |
460 | EXPORT_SYMBOL(cdev_del); | |
461 | EXPORT_SYMBOL(cdev_add); | |
462 | EXPORT_SYMBOL(register_chrdev); | |
463 | EXPORT_SYMBOL(unregister_chrdev); |