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> | |
68eef3b4 | 18 | #include <linux/seq_file.h> |
1da177e4 LT |
19 | |
20 | #include <linux/kobject.h> | |
21 | #include <linux/kobj_map.h> | |
22 | #include <linux/cdev.h> | |
58383af6 | 23 | #include <linux/mutex.h> |
1da177e4 LT |
24 | |
25 | #ifdef CONFIG_KMOD | |
26 | #include <linux/kmod.h> | |
27 | #endif | |
28 | ||
29 | static struct kobj_map *cdev_map; | |
30 | ||
58383af6 | 31 | static DEFINE_MUTEX(chrdevs_lock); |
1da177e4 LT |
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 */ | |
68eef3b4 | 41 | } *chrdevs[CHRDEV_MAJOR_HASH_SIZE]; |
1da177e4 LT |
42 | |
43 | /* index in the above */ | |
44 | static inline int major_to_index(int major) | |
45 | { | |
68eef3b4 | 46 | return major % CHRDEV_MAJOR_HASH_SIZE; |
7170be5f NH |
47 | } |
48 | ||
68eef3b4 | 49 | #ifdef CONFIG_PROC_FS |
7170be5f | 50 | |
68eef3b4 | 51 | void chrdev_show(struct seq_file *f, off_t offset) |
7170be5f NH |
52 | { |
53 | struct char_device_struct *cd; | |
7170be5f | 54 | |
68eef3b4 JK |
55 | if (offset < CHRDEV_MAJOR_HASH_SIZE) { |
56 | mutex_lock(&chrdevs_lock); | |
57 | for (cd = chrdevs[offset]; cd; cd = cd->next) | |
58 | seq_printf(f, "%3d %s\n", cd->major, cd->name); | |
59 | mutex_unlock(&chrdevs_lock); | |
1da177e4 | 60 | } |
7170be5f NH |
61 | } |
62 | ||
68eef3b4 | 63 | #endif /* CONFIG_PROC_FS */ |
1da177e4 LT |
64 | |
65 | /* | |
66 | * Register a single major with a specified minor range. | |
67 | * | |
68 | * If major == 0 this functions will dynamically allocate a major and return | |
69 | * its number. | |
70 | * | |
71 | * If major > 0 this function will attempt to reserve the passed range of | |
72 | * minors and will return zero on success. | |
73 | * | |
74 | * Returns a -ve errno on failure. | |
75 | */ | |
76 | static struct char_device_struct * | |
77 | __register_chrdev_region(unsigned int major, unsigned int baseminor, | |
78 | int minorct, const char *name) | |
79 | { | |
80 | struct char_device_struct *cd, **cp; | |
81 | int ret = 0; | |
82 | int i; | |
83 | ||
11b0b5ab | 84 | cd = kzalloc(sizeof(struct char_device_struct), GFP_KERNEL); |
1da177e4 LT |
85 | if (cd == NULL) |
86 | return ERR_PTR(-ENOMEM); | |
87 | ||
58383af6 | 88 | mutex_lock(&chrdevs_lock); |
1da177e4 LT |
89 | |
90 | /* temporary */ | |
91 | if (major == 0) { | |
92 | for (i = ARRAY_SIZE(chrdevs)-1; i > 0; i--) { | |
93 | if (chrdevs[i] == NULL) | |
94 | break; | |
95 | } | |
96 | ||
97 | if (i == 0) { | |
98 | ret = -EBUSY; | |
99 | goto out; | |
100 | } | |
101 | major = i; | |
102 | ret = major; | |
103 | } | |
104 | ||
105 | cd->major = major; | |
106 | cd->baseminor = baseminor; | |
107 | cd->minorct = minorct; | |
7170be5f | 108 | strncpy(cd->name,name, 64); |
1da177e4 LT |
109 | |
110 | i = major_to_index(major); | |
111 | ||
112 | for (cp = &chrdevs[i]; *cp; cp = &(*cp)->next) | |
113 | if ((*cp)->major > major || | |
114 | ((*cp)->major == major && (*cp)->baseminor >= baseminor)) | |
115 | break; | |
116 | if (*cp && (*cp)->major == major && | |
117 | (*cp)->baseminor < baseminor + minorct) { | |
118 | ret = -EBUSY; | |
119 | goto out; | |
120 | } | |
121 | cd->next = *cp; | |
122 | *cp = cd; | |
58383af6 | 123 | mutex_unlock(&chrdevs_lock); |
1da177e4 LT |
124 | return cd; |
125 | out: | |
58383af6 | 126 | mutex_unlock(&chrdevs_lock); |
1da177e4 LT |
127 | kfree(cd); |
128 | return ERR_PTR(ret); | |
129 | } | |
130 | ||
131 | static struct char_device_struct * | |
132 | __unregister_chrdev_region(unsigned major, unsigned baseminor, int minorct) | |
133 | { | |
134 | struct char_device_struct *cd = NULL, **cp; | |
135 | int i = major_to_index(major); | |
136 | ||
58383af6 | 137 | mutex_lock(&chrdevs_lock); |
1da177e4 LT |
138 | for (cp = &chrdevs[i]; *cp; cp = &(*cp)->next) |
139 | if ((*cp)->major == major && | |
140 | (*cp)->baseminor == baseminor && | |
141 | (*cp)->minorct == minorct) | |
142 | break; | |
143 | if (*cp) { | |
144 | cd = *cp; | |
145 | *cp = cd->next; | |
146 | } | |
58383af6 | 147 | mutex_unlock(&chrdevs_lock); |
1da177e4 LT |
148 | return cd; |
149 | } | |
150 | ||
151 | int register_chrdev_region(dev_t from, unsigned count, const char *name) | |
152 | { | |
153 | struct char_device_struct *cd; | |
154 | dev_t to = from + count; | |
155 | dev_t n, next; | |
156 | ||
157 | for (n = from; n < to; n = next) { | |
158 | next = MKDEV(MAJOR(n)+1, 0); | |
159 | if (next > to) | |
160 | next = to; | |
161 | cd = __register_chrdev_region(MAJOR(n), MINOR(n), | |
162 | next - n, name); | |
163 | if (IS_ERR(cd)) | |
164 | goto fail; | |
165 | } | |
166 | return 0; | |
167 | fail: | |
168 | to = n; | |
169 | for (n = from; n < to; n = next) { | |
170 | next = MKDEV(MAJOR(n)+1, 0); | |
171 | kfree(__unregister_chrdev_region(MAJOR(n), MINOR(n), next - n)); | |
172 | } | |
173 | return PTR_ERR(cd); | |
174 | } | |
175 | ||
176 | int alloc_chrdev_region(dev_t *dev, unsigned baseminor, unsigned count, | |
177 | const char *name) | |
178 | { | |
179 | struct char_device_struct *cd; | |
180 | cd = __register_chrdev_region(0, baseminor, count, name); | |
181 | if (IS_ERR(cd)) | |
182 | return PTR_ERR(cd); | |
183 | *dev = MKDEV(cd->major, cd->baseminor); | |
184 | return 0; | |
185 | } | |
186 | ||
187 | int register_chrdev(unsigned int major, const char *name, | |
99ac48f5 | 188 | const struct file_operations *fops) |
1da177e4 LT |
189 | { |
190 | struct char_device_struct *cd; | |
191 | struct cdev *cdev; | |
192 | char *s; | |
193 | int err = -ENOMEM; | |
194 | ||
195 | cd = __register_chrdev_region(major, 0, 256, name); | |
196 | if (IS_ERR(cd)) | |
197 | return PTR_ERR(cd); | |
198 | ||
199 | cdev = cdev_alloc(); | |
200 | if (!cdev) | |
201 | goto out2; | |
202 | ||
203 | cdev->owner = fops->owner; | |
204 | cdev->ops = fops; | |
205 | kobject_set_name(&cdev->kobj, "%s", name); | |
206 | for (s = strchr(kobject_name(&cdev->kobj),'/'); s; s = strchr(s, '/')) | |
207 | *s = '!'; | |
208 | ||
209 | err = cdev_add(cdev, MKDEV(cd->major, 0), 256); | |
210 | if (err) | |
211 | goto out; | |
212 | ||
213 | cd->cdev = cdev; | |
214 | ||
215 | return major ? 0 : cd->major; | |
216 | out: | |
217 | kobject_put(&cdev->kobj); | |
218 | out2: | |
219 | kfree(__unregister_chrdev_region(cd->major, 0, 256)); | |
220 | return err; | |
221 | } | |
222 | ||
223 | void unregister_chrdev_region(dev_t from, unsigned count) | |
224 | { | |
225 | dev_t to = from + count; | |
226 | dev_t n, next; | |
227 | ||
228 | for (n = from; n < to; n = next) { | |
229 | next = MKDEV(MAJOR(n)+1, 0); | |
230 | if (next > to) | |
231 | next = to; | |
232 | kfree(__unregister_chrdev_region(MAJOR(n), MINOR(n), next - n)); | |
233 | } | |
234 | } | |
235 | ||
236 | int unregister_chrdev(unsigned int major, const char *name) | |
237 | { | |
238 | struct char_device_struct *cd; | |
239 | cd = __unregister_chrdev_region(major, 0, 256); | |
240 | if (cd && cd->cdev) | |
241 | cdev_del(cd->cdev); | |
242 | kfree(cd); | |
243 | return 0; | |
244 | } | |
245 | ||
246 | static DEFINE_SPINLOCK(cdev_lock); | |
247 | ||
248 | static struct kobject *cdev_get(struct cdev *p) | |
249 | { | |
250 | struct module *owner = p->owner; | |
251 | struct kobject *kobj; | |
252 | ||
253 | if (owner && !try_module_get(owner)) | |
254 | return NULL; | |
255 | kobj = kobject_get(&p->kobj); | |
256 | if (!kobj) | |
257 | module_put(owner); | |
258 | return kobj; | |
259 | } | |
260 | ||
261 | void cdev_put(struct cdev *p) | |
262 | { | |
263 | if (p) { | |
7da6844c | 264 | struct module *owner = p->owner; |
1da177e4 | 265 | kobject_put(&p->kobj); |
7da6844c | 266 | module_put(owner); |
1da177e4 LT |
267 | } |
268 | } | |
269 | ||
270 | /* | |
271 | * Called every time a character special file is opened | |
272 | */ | |
273 | int chrdev_open(struct inode * inode, struct file * filp) | |
274 | { | |
275 | struct cdev *p; | |
276 | struct cdev *new = NULL; | |
277 | int ret = 0; | |
278 | ||
279 | spin_lock(&cdev_lock); | |
280 | p = inode->i_cdev; | |
281 | if (!p) { | |
282 | struct kobject *kobj; | |
283 | int idx; | |
284 | spin_unlock(&cdev_lock); | |
285 | kobj = kobj_lookup(cdev_map, inode->i_rdev, &idx); | |
286 | if (!kobj) | |
287 | return -ENXIO; | |
288 | new = container_of(kobj, struct cdev, kobj); | |
289 | spin_lock(&cdev_lock); | |
290 | p = inode->i_cdev; | |
291 | if (!p) { | |
292 | inode->i_cdev = p = new; | |
293 | inode->i_cindex = idx; | |
294 | list_add(&inode->i_devices, &p->list); | |
295 | new = NULL; | |
296 | } else if (!cdev_get(p)) | |
297 | ret = -ENXIO; | |
298 | } else if (!cdev_get(p)) | |
299 | ret = -ENXIO; | |
300 | spin_unlock(&cdev_lock); | |
301 | cdev_put(new); | |
302 | if (ret) | |
303 | return ret; | |
304 | filp->f_op = fops_get(p->ops); | |
305 | if (!filp->f_op) { | |
306 | cdev_put(p); | |
307 | return -ENXIO; | |
308 | } | |
309 | if (filp->f_op->open) { | |
310 | lock_kernel(); | |
311 | ret = filp->f_op->open(inode,filp); | |
312 | unlock_kernel(); | |
313 | } | |
314 | if (ret) | |
315 | cdev_put(p); | |
316 | return ret; | |
317 | } | |
318 | ||
319 | void cd_forget(struct inode *inode) | |
320 | { | |
321 | spin_lock(&cdev_lock); | |
322 | list_del_init(&inode->i_devices); | |
323 | inode->i_cdev = NULL; | |
324 | spin_unlock(&cdev_lock); | |
325 | } | |
326 | ||
75c96f85 | 327 | static void cdev_purge(struct cdev *cdev) |
1da177e4 LT |
328 | { |
329 | spin_lock(&cdev_lock); | |
330 | while (!list_empty(&cdev->list)) { | |
331 | struct inode *inode; | |
332 | inode = container_of(cdev->list.next, struct inode, i_devices); | |
333 | list_del_init(&inode->i_devices); | |
334 | inode->i_cdev = NULL; | |
335 | } | |
336 | spin_unlock(&cdev_lock); | |
337 | } | |
338 | ||
339 | /* | |
340 | * Dummy default file-operations: the only thing this does | |
341 | * is contain the open that then fills in the correct operations | |
342 | * depending on the special file... | |
343 | */ | |
4b6f5d20 | 344 | const struct file_operations def_chr_fops = { |
1da177e4 LT |
345 | .open = chrdev_open, |
346 | }; | |
347 | ||
348 | static struct kobject *exact_match(dev_t dev, int *part, void *data) | |
349 | { | |
350 | struct cdev *p = data; | |
351 | return &p->kobj; | |
352 | } | |
353 | ||
354 | static int exact_lock(dev_t dev, void *data) | |
355 | { | |
356 | struct cdev *p = data; | |
357 | return cdev_get(p) ? 0 : -1; | |
358 | } | |
359 | ||
360 | int cdev_add(struct cdev *p, dev_t dev, unsigned count) | |
361 | { | |
362 | p->dev = dev; | |
363 | p->count = count; | |
364 | return kobj_map(cdev_map, dev, count, NULL, exact_match, exact_lock, p); | |
365 | } | |
366 | ||
367 | static void cdev_unmap(dev_t dev, unsigned count) | |
368 | { | |
369 | kobj_unmap(cdev_map, dev, count); | |
370 | } | |
371 | ||
372 | void cdev_del(struct cdev *p) | |
373 | { | |
374 | cdev_unmap(p->dev, p->count); | |
375 | kobject_put(&p->kobj); | |
376 | } | |
377 | ||
378 | ||
379 | static void cdev_default_release(struct kobject *kobj) | |
380 | { | |
381 | struct cdev *p = container_of(kobj, struct cdev, kobj); | |
382 | cdev_purge(p); | |
383 | } | |
384 | ||
385 | static void cdev_dynamic_release(struct kobject *kobj) | |
386 | { | |
387 | struct cdev *p = container_of(kobj, struct cdev, kobj); | |
388 | cdev_purge(p); | |
389 | kfree(p); | |
390 | } | |
391 | ||
392 | static struct kobj_type ktype_cdev_default = { | |
393 | .release = cdev_default_release, | |
394 | }; | |
395 | ||
396 | static struct kobj_type ktype_cdev_dynamic = { | |
397 | .release = cdev_dynamic_release, | |
398 | }; | |
399 | ||
400 | struct cdev *cdev_alloc(void) | |
401 | { | |
11b0b5ab | 402 | struct cdev *p = kzalloc(sizeof(struct cdev), GFP_KERNEL); |
1da177e4 | 403 | if (p) { |
1da177e4 LT |
404 | p->kobj.ktype = &ktype_cdev_dynamic; |
405 | INIT_LIST_HEAD(&p->list); | |
406 | kobject_init(&p->kobj); | |
407 | } | |
408 | return p; | |
409 | } | |
410 | ||
99ac48f5 | 411 | void cdev_init(struct cdev *cdev, const struct file_operations *fops) |
1da177e4 LT |
412 | { |
413 | memset(cdev, 0, sizeof *cdev); | |
414 | INIT_LIST_HEAD(&cdev->list); | |
415 | cdev->kobj.ktype = &ktype_cdev_default; | |
416 | kobject_init(&cdev->kobj); | |
417 | cdev->ops = fops; | |
418 | } | |
419 | ||
420 | static struct kobject *base_probe(dev_t dev, int *part, void *data) | |
421 | { | |
422 | if (request_module("char-major-%d-%d", MAJOR(dev), MINOR(dev)) > 0) | |
423 | /* Make old-style 2.4 aliases work */ | |
424 | request_module("char-major-%d", MAJOR(dev)); | |
425 | return NULL; | |
426 | } | |
427 | ||
428 | void __init chrdev_init(void) | |
429 | { | |
430 | cdev_map = kobj_map_init(base_probe, &chrdevs_lock); | |
431 | } | |
432 | ||
433 | ||
434 | /* Let modules do char dev stuff */ | |
435 | EXPORT_SYMBOL(register_chrdev_region); | |
436 | EXPORT_SYMBOL(unregister_chrdev_region); | |
437 | EXPORT_SYMBOL(alloc_chrdev_region); | |
438 | EXPORT_SYMBOL(cdev_init); | |
439 | EXPORT_SYMBOL(cdev_alloc); | |
440 | EXPORT_SYMBOL(cdev_del); | |
441 | EXPORT_SYMBOL(cdev_add); | |
442 | EXPORT_SYMBOL(register_chrdev); | |
443 | EXPORT_SYMBOL(unregister_chrdev); |