Contents of /alx-src/tags/kernel26-2.6.12-alx-r9/fs/char_dev.c
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Wed Mar 4 11:03:09 2009 UTC (15 years, 6 months ago) by niro
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File size: 9422 byte(s)
Wed Mar 4 11:03:09 2009 UTC (15 years, 6 months ago) by niro
File MIME type: text/plain
File size: 9422 byte(s)
Tag kernel26-2.6.12-alx-r9
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 | |
29 | #define MAX_PROBE_HASH 255 /* random */ |
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; |
38 | const char *name; |
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 | |
49 | /* get char device names in somewhat random order */ |
50 | int get_chrdev_list(char *page) |
51 | { |
52 | struct char_device_struct *cd; |
53 | int i, len; |
54 | |
55 | len = sprintf(page, "Character devices:\n"); |
56 | |
57 | down(&chrdevs_lock); |
58 | for (i = 0; i < ARRAY_SIZE(chrdevs) ; i++) { |
59 | for (cd = chrdevs[i]; cd; cd = cd->next) |
60 | len += sprintf(page+len, "%3d %s\n", |
61 | cd->major, cd->name); |
62 | } |
63 | up(&chrdevs_lock); |
64 | |
65 | return len; |
66 | } |
67 | |
68 | /* |
69 | * Register a single major with a specified minor range. |
70 | * |
71 | * If major == 0 this functions will dynamically allocate a major and return |
72 | * its number. |
73 | * |
74 | * If major > 0 this function will attempt to reserve the passed range of |
75 | * minors and will return zero on success. |
76 | * |
77 | * Returns a -ve errno on failure. |
78 | */ |
79 | static struct char_device_struct * |
80 | __register_chrdev_region(unsigned int major, unsigned int baseminor, |
81 | int minorct, const char *name) |
82 | { |
83 | struct char_device_struct *cd, **cp; |
84 | int ret = 0; |
85 | int i; |
86 | |
87 | cd = kmalloc(sizeof(struct char_device_struct), GFP_KERNEL); |
88 | if (cd == NULL) |
89 | return ERR_PTR(-ENOMEM); |
90 | |
91 | memset(cd, 0, sizeof(struct char_device_struct)); |
92 | |
93 | down(&chrdevs_lock); |
94 | |
95 | /* temporary */ |
96 | if (major == 0) { |
97 | for (i = ARRAY_SIZE(chrdevs)-1; i > 0; i--) { |
98 | if (chrdevs[i] == NULL) |
99 | break; |
100 | } |
101 | |
102 | if (i == 0) { |
103 | ret = -EBUSY; |
104 | goto out; |
105 | } |
106 | major = i; |
107 | ret = major; |
108 | } |
109 | |
110 | cd->major = major; |
111 | cd->baseminor = baseminor; |
112 | cd->minorct = minorct; |
113 | cd->name = name; |
114 | |
115 | i = major_to_index(major); |
116 | |
117 | for (cp = &chrdevs[i]; *cp; cp = &(*cp)->next) |
118 | if ((*cp)->major > major || |
119 | ((*cp)->major == major && (*cp)->baseminor >= baseminor)) |
120 | break; |
121 | if (*cp && (*cp)->major == major && |
122 | (*cp)->baseminor < baseminor + minorct) { |
123 | ret = -EBUSY; |
124 | goto out; |
125 | } |
126 | cd->next = *cp; |
127 | *cp = cd; |
128 | up(&chrdevs_lock); |
129 | return cd; |
130 | out: |
131 | up(&chrdevs_lock); |
132 | kfree(cd); |
133 | return ERR_PTR(ret); |
134 | } |
135 | |
136 | static struct char_device_struct * |
137 | __unregister_chrdev_region(unsigned major, unsigned baseminor, int minorct) |
138 | { |
139 | struct char_device_struct *cd = NULL, **cp; |
140 | int i = major_to_index(major); |
141 | |
142 | down(&chrdevs_lock); |
143 | for (cp = &chrdevs[i]; *cp; cp = &(*cp)->next) |
144 | if ((*cp)->major == major && |
145 | (*cp)->baseminor == baseminor && |
146 | (*cp)->minorct == minorct) |
147 | break; |
148 | if (*cp) { |
149 | cd = *cp; |
150 | *cp = cd->next; |
151 | } |
152 | up(&chrdevs_lock); |
153 | return cd; |
154 | } |
155 | |
156 | int register_chrdev_region(dev_t from, unsigned count, const char *name) |
157 | { |
158 | struct char_device_struct *cd; |
159 | dev_t to = from + count; |
160 | dev_t n, next; |
161 | |
162 | for (n = from; n < to; n = next) { |
163 | next = MKDEV(MAJOR(n)+1, 0); |
164 | if (next > to) |
165 | next = to; |
166 | cd = __register_chrdev_region(MAJOR(n), MINOR(n), |
167 | next - n, name); |
168 | if (IS_ERR(cd)) |
169 | goto fail; |
170 | } |
171 | return 0; |
172 | fail: |
173 | to = n; |
174 | for (n = from; n < to; n = next) { |
175 | next = MKDEV(MAJOR(n)+1, 0); |
176 | kfree(__unregister_chrdev_region(MAJOR(n), MINOR(n), next - n)); |
177 | } |
178 | return PTR_ERR(cd); |
179 | } |
180 | |
181 | int alloc_chrdev_region(dev_t *dev, unsigned baseminor, unsigned count, |
182 | const char *name) |
183 | { |
184 | struct char_device_struct *cd; |
185 | cd = __register_chrdev_region(0, baseminor, count, name); |
186 | if (IS_ERR(cd)) |
187 | return PTR_ERR(cd); |
188 | *dev = MKDEV(cd->major, cd->baseminor); |
189 | return 0; |
190 | } |
191 | |
192 | int register_chrdev(unsigned int major, const char *name, |
193 | struct file_operations *fops) |
194 | { |
195 | struct char_device_struct *cd; |
196 | struct cdev *cdev; |
197 | char *s; |
198 | int err = -ENOMEM; |
199 | |
200 | cd = __register_chrdev_region(major, 0, 256, name); |
201 | if (IS_ERR(cd)) |
202 | return PTR_ERR(cd); |
203 | |
204 | cdev = cdev_alloc(); |
205 | if (!cdev) |
206 | goto out2; |
207 | |
208 | cdev->owner = fops->owner; |
209 | cdev->ops = fops; |
210 | kobject_set_name(&cdev->kobj, "%s", name); |
211 | for (s = strchr(kobject_name(&cdev->kobj),'/'); s; s = strchr(s, '/')) |
212 | *s = '!'; |
213 | |
214 | err = cdev_add(cdev, MKDEV(cd->major, 0), 256); |
215 | if (err) |
216 | goto out; |
217 | |
218 | cd->cdev = cdev; |
219 | |
220 | return major ? 0 : cd->major; |
221 | out: |
222 | kobject_put(&cdev->kobj); |
223 | out2: |
224 | kfree(__unregister_chrdev_region(cd->major, 0, 256)); |
225 | return err; |
226 | } |
227 | |
228 | void unregister_chrdev_region(dev_t from, unsigned count) |
229 | { |
230 | dev_t to = from + count; |
231 | dev_t n, next; |
232 | |
233 | for (n = from; n < to; n = next) { |
234 | next = MKDEV(MAJOR(n)+1, 0); |
235 | if (next > to) |
236 | next = to; |
237 | kfree(__unregister_chrdev_region(MAJOR(n), MINOR(n), next - n)); |
238 | } |
239 | } |
240 | |
241 | int unregister_chrdev(unsigned int major, const char *name) |
242 | { |
243 | struct char_device_struct *cd; |
244 | cd = __unregister_chrdev_region(major, 0, 256); |
245 | if (cd && cd->cdev) |
246 | cdev_del(cd->cdev); |
247 | kfree(cd); |
248 | return 0; |
249 | } |
250 | |
251 | static DEFINE_SPINLOCK(cdev_lock); |
252 | |
253 | static struct kobject *cdev_get(struct cdev *p) |
254 | { |
255 | struct module *owner = p->owner; |
256 | struct kobject *kobj; |
257 | |
258 | if (owner && !try_module_get(owner)) |
259 | return NULL; |
260 | kobj = kobject_get(&p->kobj); |
261 | if (!kobj) |
262 | module_put(owner); |
263 | return kobj; |
264 | } |
265 | |
266 | void cdev_put(struct cdev *p) |
267 | { |
268 | if (p) { |
269 | kobject_put(&p->kobj); |
270 | module_put(p->owner); |
271 | } |
272 | } |
273 | |
274 | /* |
275 | * Called every time a character special file is opened |
276 | */ |
277 | int chrdev_open(struct inode * inode, struct file * filp) |
278 | { |
279 | struct cdev *p; |
280 | struct cdev *new = NULL; |
281 | int ret = 0; |
282 | |
283 | spin_lock(&cdev_lock); |
284 | p = inode->i_cdev; |
285 | if (!p) { |
286 | struct kobject *kobj; |
287 | int idx; |
288 | spin_unlock(&cdev_lock); |
289 | kobj = kobj_lookup(cdev_map, inode->i_rdev, &idx); |
290 | if (!kobj) |
291 | return -ENXIO; |
292 | new = container_of(kobj, struct cdev, kobj); |
293 | spin_lock(&cdev_lock); |
294 | p = inode->i_cdev; |
295 | if (!p) { |
296 | inode->i_cdev = p = new; |
297 | inode->i_cindex = idx; |
298 | list_add(&inode->i_devices, &p->list); |
299 | new = NULL; |
300 | } else if (!cdev_get(p)) |
301 | ret = -ENXIO; |
302 | } else if (!cdev_get(p)) |
303 | ret = -ENXIO; |
304 | spin_unlock(&cdev_lock); |
305 | cdev_put(new); |
306 | if (ret) |
307 | return ret; |
308 | filp->f_op = fops_get(p->ops); |
309 | if (!filp->f_op) { |
310 | cdev_put(p); |
311 | return -ENXIO; |
312 | } |
313 | if (filp->f_op->open) { |
314 | lock_kernel(); |
315 | ret = filp->f_op->open(inode,filp); |
316 | unlock_kernel(); |
317 | } |
318 | if (ret) |
319 | cdev_put(p); |
320 | return ret; |
321 | } |
322 | |
323 | void cd_forget(struct inode *inode) |
324 | { |
325 | spin_lock(&cdev_lock); |
326 | list_del_init(&inode->i_devices); |
327 | inode->i_cdev = NULL; |
328 | spin_unlock(&cdev_lock); |
329 | } |
330 | |
331 | static void cdev_purge(struct cdev *cdev) |
332 | { |
333 | spin_lock(&cdev_lock); |
334 | while (!list_empty(&cdev->list)) { |
335 | struct inode *inode; |
336 | inode = container_of(cdev->list.next, struct inode, i_devices); |
337 | list_del_init(&inode->i_devices); |
338 | inode->i_cdev = NULL; |
339 | } |
340 | spin_unlock(&cdev_lock); |
341 | } |
342 | |
343 | /* |
344 | * Dummy default file-operations: the only thing this does |
345 | * is contain the open that then fills in the correct operations |
346 | * depending on the special file... |
347 | */ |
348 | struct file_operations def_chr_fops = { |
349 | .open = chrdev_open, |
350 | }; |
351 | |
352 | static struct kobject *exact_match(dev_t dev, int *part, void *data) |
353 | { |
354 | struct cdev *p = data; |
355 | return &p->kobj; |
356 | } |
357 | |
358 | static int exact_lock(dev_t dev, void *data) |
359 | { |
360 | struct cdev *p = data; |
361 | return cdev_get(p) ? 0 : -1; |
362 | } |
363 | |
364 | int cdev_add(struct cdev *p, dev_t dev, unsigned count) |
365 | { |
366 | p->dev = dev; |
367 | p->count = count; |
368 | return kobj_map(cdev_map, dev, count, NULL, exact_match, exact_lock, p); |
369 | } |
370 | |
371 | static void cdev_unmap(dev_t dev, unsigned count) |
372 | { |
373 | kobj_unmap(cdev_map, dev, count); |
374 | } |
375 | |
376 | void cdev_del(struct cdev *p) |
377 | { |
378 | cdev_unmap(p->dev, p->count); |
379 | kobject_put(&p->kobj); |
380 | } |
381 | |
382 | |
383 | static void cdev_default_release(struct kobject *kobj) |
384 | { |
385 | struct cdev *p = container_of(kobj, struct cdev, kobj); |
386 | cdev_purge(p); |
387 | } |
388 | |
389 | static void cdev_dynamic_release(struct kobject *kobj) |
390 | { |
391 | struct cdev *p = container_of(kobj, struct cdev, kobj); |
392 | cdev_purge(p); |
393 | kfree(p); |
394 | } |
395 | |
396 | static struct kobj_type ktype_cdev_default = { |
397 | .release = cdev_default_release, |
398 | }; |
399 | |
400 | static struct kobj_type ktype_cdev_dynamic = { |
401 | .release = cdev_dynamic_release, |
402 | }; |
403 | |
404 | struct cdev *cdev_alloc(void) |
405 | { |
406 | struct cdev *p = kmalloc(sizeof(struct cdev), GFP_KERNEL); |
407 | if (p) { |
408 | memset(p, 0, sizeof(struct cdev)); |
409 | p->kobj.ktype = &ktype_cdev_dynamic; |
410 | INIT_LIST_HEAD(&p->list); |
411 | kobject_init(&p->kobj); |
412 | } |
413 | return p; |
414 | } |
415 | |
416 | void cdev_init(struct cdev *cdev, struct file_operations *fops) |
417 | { |
418 | memset(cdev, 0, sizeof *cdev); |
419 | INIT_LIST_HEAD(&cdev->list); |
420 | cdev->kobj.ktype = &ktype_cdev_default; |
421 | kobject_init(&cdev->kobj); |
422 | cdev->ops = fops; |
423 | } |
424 | |
425 | static struct kobject *base_probe(dev_t dev, int *part, void *data) |
426 | { |
427 | if (request_module("char-major-%d-%d", MAJOR(dev), MINOR(dev)) > 0) |
428 | /* Make old-style 2.4 aliases work */ |
429 | request_module("char-major-%d", MAJOR(dev)); |
430 | return NULL; |
431 | } |
432 | |
433 | void __init chrdev_init(void) |
434 | { |
435 | cdev_map = kobj_map_init(base_probe, &chrdevs_lock); |
436 | } |
437 | |
438 | |
439 | /* Let modules do char dev stuff */ |
440 | EXPORT_SYMBOL(register_chrdev_region); |
441 | EXPORT_SYMBOL(unregister_chrdev_region); |
442 | EXPORT_SYMBOL(alloc_chrdev_region); |
443 | EXPORT_SYMBOL(cdev_init); |
444 | EXPORT_SYMBOL(cdev_alloc); |
445 | EXPORT_SYMBOL(cdev_del); |
446 | EXPORT_SYMBOL(cdev_add); |
447 | EXPORT_SYMBOL(register_chrdev); |
448 | EXPORT_SYMBOL(unregister_chrdev); |