| 1 | // SPDX-License-Identifier: GPL-2.0 |
| 2 | /* |
| 3 | * linux/fs/char_dev.c |
| 4 | * |
| 5 | * Copyright (C) 1991, 1992 Linus Torvalds |
| 6 | */ |
| 7 | |
| 8 | #include <linux/init.h> |
| 9 | #include <linux/fs.h> |
| 10 | #include <linux/kdev_t.h> |
| 11 | #include <linux/slab.h> |
| 12 | #include <linux/string.h> |
| 13 | |
| 14 | #include <linux/major.h> |
| 15 | #include <linux/errno.h> |
| 16 | #include <linux/module.h> |
| 17 | #include <linux/seq_file.h> |
| 18 | |
| 19 | #include <linux/kobject.h> |
| 20 | #include <linux/kobj_map.h> |
| 21 | #include <linux/cdev.h> |
| 22 | #include <linux/mutex.h> |
| 23 | #include <linux/backing-dev.h> |
| 24 | #include <linux/tty.h> |
| 25 | |
| 26 | #include "internal.h" |
| 27 | |
| 28 | static struct kobj_map *cdev_map; |
| 29 | |
| 30 | static DEFINE_MUTEX(chrdevs_lock); |
| 31 | |
| 32 | #define CHRDEV_MAJOR_HASH_SIZE 255 |
| 33 | |
| 34 | static struct char_device_struct { |
| 35 | struct char_device_struct *next; |
| 36 | unsigned int major; |
| 37 | unsigned int baseminor; |
| 38 | int minorct; |
| 39 | char name[64]; |
| 40 | struct cdev *cdev; /* will die */ |
| 41 | } *chrdevs[CHRDEV_MAJOR_HASH_SIZE]; |
| 42 | |
| 43 | /* index in the above */ |
| 44 | static inline int major_to_index(unsigned major) |
| 45 | { |
| 46 | return major % CHRDEV_MAJOR_HASH_SIZE; |
| 47 | } |
| 48 | |
| 49 | #ifdef CONFIG_PROC_FS |
| 50 | |
| 51 | void chrdev_show(struct seq_file *f, off_t offset) |
| 52 | { |
| 53 | struct char_device_struct *cd; |
| 54 | |
| 55 | mutex_lock(&chrdevs_lock); |
| 56 | for (cd = chrdevs[major_to_index(offset)]; cd; cd = cd->next) { |
| 57 | if (cd->major == offset) |
| 58 | seq_printf(f, "%3d %s\n", cd->major, cd->name); |
| 59 | } |
| 60 | mutex_unlock(&chrdevs_lock); |
| 61 | } |
| 62 | |
| 63 | #endif /* CONFIG_PROC_FS */ |
| 64 | |
| 65 | static int find_dynamic_major(void) |
| 66 | { |
| 67 | int i; |
| 68 | struct char_device_struct *cd; |
| 69 | |
| 70 | for (i = ARRAY_SIZE(chrdevs)-1; i >= CHRDEV_MAJOR_DYN_END; i--) { |
| 71 | if (chrdevs[i] == NULL) |
| 72 | return i; |
| 73 | } |
| 74 | |
| 75 | for (i = CHRDEV_MAJOR_DYN_EXT_START; |
| 76 | i >= CHRDEV_MAJOR_DYN_EXT_END; i--) { |
| 77 | for (cd = chrdevs[major_to_index(i)]; cd; cd = cd->next) |
| 78 | if (cd->major == i) |
| 79 | break; |
| 80 | |
| 81 | if (cd == NULL) |
| 82 | return i; |
| 83 | } |
| 84 | |
| 85 | return -EBUSY; |
| 86 | } |
| 87 | |
| 88 | /* |
| 89 | * Register a single major with a specified minor range. |
| 90 | * |
| 91 | * If major == 0 this function will dynamically allocate an unused major. |
| 92 | * If major > 0 this function will attempt to reserve the range of minors |
| 93 | * with given major. |
| 94 | * |
| 95 | */ |
| 96 | static struct char_device_struct * |
| 97 | __register_chrdev_region(unsigned int major, unsigned int baseminor, |
| 98 | int minorct, const char *name) |
| 99 | { |
| 100 | struct char_device_struct *cd, *curr, *prev = NULL; |
| 101 | int ret; |
| 102 | int i; |
| 103 | |
| 104 | if (major >= CHRDEV_MAJOR_MAX) { |
| 105 | pr_err("CHRDEV \"%s\" major requested (%u) is greater than the maximum (%u)\n", |
| 106 | name, major, CHRDEV_MAJOR_MAX-1); |
| 107 | return ERR_PTR(-EINVAL); |
| 108 | } |
| 109 | |
| 110 | if (minorct > MINORMASK + 1 - baseminor) { |
| 111 | pr_err("CHRDEV \"%s\" minor range requested (%u-%u) is out of range of maximum range (%u-%u) for a single major\n", |
| 112 | name, baseminor, baseminor + minorct - 1, 0, MINORMASK); |
| 113 | return ERR_PTR(-EINVAL); |
| 114 | } |
| 115 | |
| 116 | cd = kzalloc(sizeof(struct char_device_struct), GFP_KERNEL); |
| 117 | if (cd == NULL) |
| 118 | return ERR_PTR(-ENOMEM); |
| 119 | |
| 120 | mutex_lock(&chrdevs_lock); |
| 121 | |
| 122 | if (major == 0) { |
| 123 | ret = find_dynamic_major(); |
| 124 | if (ret < 0) { |
| 125 | pr_err("CHRDEV \"%s\" dynamic allocation region is full\n", |
| 126 | name); |
| 127 | goto out; |
| 128 | } |
| 129 | major = ret; |
| 130 | } |
| 131 | |
| 132 | ret = -EBUSY; |
| 133 | i = major_to_index(major); |
| 134 | for (curr = chrdevs[i]; curr; prev = curr, curr = curr->next) { |
| 135 | if (curr->major < major) |
| 136 | continue; |
| 137 | |
| 138 | if (curr->major > major) |
| 139 | break; |
| 140 | |
| 141 | if (curr->baseminor + curr->minorct <= baseminor) |
| 142 | continue; |
| 143 | |
| 144 | if (curr->baseminor >= baseminor + minorct) |
| 145 | break; |
| 146 | |
| 147 | goto out; |
| 148 | } |
| 149 | |
| 150 | cd->major = major; |
| 151 | cd->baseminor = baseminor; |
| 152 | cd->minorct = minorct; |
| 153 | strlcpy(cd->name, name, sizeof(cd->name)); |
| 154 | |
| 155 | if (!prev) { |
| 156 | cd->next = curr; |
| 157 | chrdevs[i] = cd; |
| 158 | } else { |
| 159 | cd->next = prev->next; |
| 160 | prev->next = cd; |
| 161 | } |
| 162 | |
| 163 | mutex_unlock(&chrdevs_lock); |
| 164 | return cd; |
| 165 | out: |
| 166 | mutex_unlock(&chrdevs_lock); |
| 167 | kfree(cd); |
| 168 | return ERR_PTR(ret); |
| 169 | } |
| 170 | |
| 171 | static struct char_device_struct * |
| 172 | __unregister_chrdev_region(unsigned major, unsigned baseminor, int minorct) |
| 173 | { |
| 174 | struct char_device_struct *cd = NULL, **cp; |
| 175 | int i = major_to_index(major); |
| 176 | |
| 177 | mutex_lock(&chrdevs_lock); |
| 178 | for (cp = &chrdevs[i]; *cp; cp = &(*cp)->next) |
| 179 | if ((*cp)->major == major && |
| 180 | (*cp)->baseminor == baseminor && |
| 181 | (*cp)->minorct == minorct) |
| 182 | break; |
| 183 | if (*cp) { |
| 184 | cd = *cp; |
| 185 | *cp = cd->next; |
| 186 | } |
| 187 | mutex_unlock(&chrdevs_lock); |
| 188 | return cd; |
| 189 | } |
| 190 | |
| 191 | /** |
| 192 | * register_chrdev_region() - register a range of device numbers |
| 193 | * @from: the first in the desired range of device numbers; must include |
| 194 | * the major number. |
| 195 | * @count: the number of consecutive device numbers required |
| 196 | * @name: the name of the device or driver. |
| 197 | * |
| 198 | * Return value is zero on success, a negative error code on failure. |
| 199 | */ |
| 200 | int register_chrdev_region(dev_t from, unsigned count, const char *name) |
| 201 | { |
| 202 | struct char_device_struct *cd; |
| 203 | dev_t to = from + count; |
| 204 | dev_t n, next; |
| 205 | |
| 206 | for (n = from; n < to; n = next) { |
| 207 | next = MKDEV(MAJOR(n)+1, 0); |
| 208 | if (next > to) |
| 209 | next = to; |
| 210 | cd = __register_chrdev_region(MAJOR(n), MINOR(n), |
| 211 | next - n, name); |
| 212 | if (IS_ERR(cd)) |
| 213 | goto fail; |
| 214 | } |
| 215 | return 0; |
| 216 | fail: |
| 217 | to = n; |
| 218 | for (n = from; n < to; n = next) { |
| 219 | next = MKDEV(MAJOR(n)+1, 0); |
| 220 | kfree(__unregister_chrdev_region(MAJOR(n), MINOR(n), next - n)); |
| 221 | } |
| 222 | return PTR_ERR(cd); |
| 223 | } |
| 224 | |
| 225 | /** |
| 226 | * alloc_chrdev_region() - register a range of char device numbers |
| 227 | * @dev: output parameter for first assigned number |
| 228 | * @baseminor: first of the requested range of minor numbers |
| 229 | * @count: the number of minor numbers required |
| 230 | * @name: the name of the associated device or driver |
| 231 | * |
| 232 | * Allocates a range of char device numbers. The major number will be |
| 233 | * chosen dynamically, and returned (along with the first minor number) |
| 234 | * in @dev. Returns zero or a negative error code. |
| 235 | */ |
| 236 | int alloc_chrdev_region(dev_t *dev, unsigned baseminor, unsigned count, |
| 237 | const char *name) |
| 238 | { |
| 239 | struct char_device_struct *cd; |
| 240 | cd = __register_chrdev_region(0, baseminor, count, name); |
| 241 | if (IS_ERR(cd)) |
| 242 | return PTR_ERR(cd); |
| 243 | *dev = MKDEV(cd->major, cd->baseminor); |
| 244 | return 0; |
| 245 | } |
| 246 | |
| 247 | /** |
| 248 | * __register_chrdev() - create and register a cdev occupying a range of minors |
| 249 | * @major: major device number or 0 for dynamic allocation |
| 250 | * @baseminor: first of the requested range of minor numbers |
| 251 | * @count: the number of minor numbers required |
| 252 | * @name: name of this range of devices |
| 253 | * @fops: file operations associated with this devices |
| 254 | * |
| 255 | * If @major == 0 this functions will dynamically allocate a major and return |
| 256 | * its number. |
| 257 | * |
| 258 | * If @major > 0 this function will attempt to reserve a device with the given |
| 259 | * major number and will return zero on success. |
| 260 | * |
| 261 | * Returns a -ve errno on failure. |
| 262 | * |
| 263 | * The name of this device has nothing to do with the name of the device in |
| 264 | * /dev. It only helps to keep track of the different owners of devices. If |
| 265 | * your module name has only one type of devices it's ok to use e.g. the name |
| 266 | * of the module here. |
| 267 | */ |
| 268 | int __register_chrdev(unsigned int major, unsigned int baseminor, |
| 269 | unsigned int count, const char *name, |
| 270 | const struct file_operations *fops) |
| 271 | { |
| 272 | struct char_device_struct *cd; |
| 273 | struct cdev *cdev; |
| 274 | int err = -ENOMEM; |
| 275 | |
| 276 | cd = __register_chrdev_region(major, baseminor, count, name); |
| 277 | if (IS_ERR(cd)) |
| 278 | return PTR_ERR(cd); |
| 279 | |
| 280 | cdev = cdev_alloc(); |
| 281 | if (!cdev) |
| 282 | goto out2; |
| 283 | |
| 284 | cdev->owner = fops->owner; |
| 285 | cdev->ops = fops; |
| 286 | kobject_set_name(&cdev->kobj, "%s", name); |
| 287 | |
| 288 | err = cdev_add(cdev, MKDEV(cd->major, baseminor), count); |
| 289 | if (err) |
| 290 | goto out; |
| 291 | |
| 292 | cd->cdev = cdev; |
| 293 | |
| 294 | return major ? 0 : cd->major; |
| 295 | out: |
| 296 | kobject_put(&cdev->kobj); |
| 297 | out2: |
| 298 | kfree(__unregister_chrdev_region(cd->major, baseminor, count)); |
| 299 | return err; |
| 300 | } |
| 301 | |
| 302 | /** |
| 303 | * unregister_chrdev_region() - unregister a range of device numbers |
| 304 | * @from: the first in the range of numbers to unregister |
| 305 | * @count: the number of device numbers to unregister |
| 306 | * |
| 307 | * This function will unregister a range of @count device numbers, |
| 308 | * starting with @from. The caller should normally be the one who |
| 309 | * allocated those numbers in the first place... |
| 310 | */ |
| 311 | void unregister_chrdev_region(dev_t from, unsigned count) |
| 312 | { |
| 313 | dev_t to = from + count; |
| 314 | dev_t n, next; |
| 315 | |
| 316 | for (n = from; n < to; n = next) { |
| 317 | next = MKDEV(MAJOR(n)+1, 0); |
| 318 | if (next > to) |
| 319 | next = to; |
| 320 | kfree(__unregister_chrdev_region(MAJOR(n), MINOR(n), next - n)); |
| 321 | } |
| 322 | } |
| 323 | |
| 324 | /** |
| 325 | * __unregister_chrdev - unregister and destroy a cdev |
| 326 | * @major: major device number |
| 327 | * @baseminor: first of the range of minor numbers |
| 328 | * @count: the number of minor numbers this cdev is occupying |
| 329 | * @name: name of this range of devices |
| 330 | * |
| 331 | * Unregister and destroy the cdev occupying the region described by |
| 332 | * @major, @baseminor and @count. This function undoes what |
| 333 | * __register_chrdev() did. |
| 334 | */ |
| 335 | void __unregister_chrdev(unsigned int major, unsigned int baseminor, |
| 336 | unsigned int count, const char *name) |
| 337 | { |
| 338 | struct char_device_struct *cd; |
| 339 | |
| 340 | cd = __unregister_chrdev_region(major, baseminor, count); |
| 341 | if (cd && cd->cdev) |
| 342 | cdev_del(cd->cdev); |
| 343 | kfree(cd); |
| 344 | } |
| 345 | |
| 346 | static DEFINE_SPINLOCK(cdev_lock); |
| 347 | |
| 348 | static struct kobject *cdev_get(struct cdev *p) |
| 349 | { |
| 350 | struct module *owner = p->owner; |
| 351 | struct kobject *kobj; |
| 352 | |
| 353 | if (owner && !try_module_get(owner)) |
| 354 | return NULL; |
| 355 | kobj = kobject_get_unless_zero(&p->kobj); |
| 356 | if (!kobj) |
| 357 | module_put(owner); |
| 358 | return kobj; |
| 359 | } |
| 360 | |
| 361 | void cdev_put(struct cdev *p) |
| 362 | { |
| 363 | if (p) { |
| 364 | struct module *owner = p->owner; |
| 365 | kobject_put(&p->kobj); |
| 366 | module_put(owner); |
| 367 | } |
| 368 | } |
| 369 | |
| 370 | /* |
| 371 | * Called every time a character special file is opened |
| 372 | */ |
| 373 | static int chrdev_open(struct inode *inode, struct file *filp) |
| 374 | { |
| 375 | const struct file_operations *fops; |
| 376 | struct cdev *p; |
| 377 | struct cdev *new = NULL; |
| 378 | int ret = 0; |
| 379 | |
| 380 | spin_lock(&cdev_lock); |
| 381 | p = inode->i_cdev; |
| 382 | if (!p) { |
| 383 | struct kobject *kobj; |
| 384 | int idx; |
| 385 | spin_unlock(&cdev_lock); |
| 386 | kobj = kobj_lookup(cdev_map, inode->i_rdev, &idx); |
| 387 | if (!kobj) |
| 388 | return -ENXIO; |
| 389 | new = container_of(kobj, struct cdev, kobj); |
| 390 | spin_lock(&cdev_lock); |
| 391 | /* Check i_cdev again in case somebody beat us to it while |
| 392 | we dropped the lock. */ |
| 393 | p = inode->i_cdev; |
| 394 | if (!p) { |
| 395 | inode->i_cdev = p = new; |
| 396 | list_add(&inode->i_devices, &p->list); |
| 397 | new = NULL; |
| 398 | } else if (!cdev_get(p)) |
| 399 | ret = -ENXIO; |
| 400 | } else if (!cdev_get(p)) |
| 401 | ret = -ENXIO; |
| 402 | spin_unlock(&cdev_lock); |
| 403 | cdev_put(new); |
| 404 | if (ret) |
| 405 | return ret; |
| 406 | |
| 407 | ret = -ENXIO; |
| 408 | fops = fops_get(p->ops); |
| 409 | if (!fops) |
| 410 | goto out_cdev_put; |
| 411 | |
| 412 | replace_fops(filp, fops); |
| 413 | if (filp->f_op->open) { |
| 414 | ret = filp->f_op->open(inode, filp); |
| 415 | if (ret) |
| 416 | goto out_cdev_put; |
| 417 | } |
| 418 | |
| 419 | return 0; |
| 420 | |
| 421 | out_cdev_put: |
| 422 | cdev_put(p); |
| 423 | return ret; |
| 424 | } |
| 425 | |
| 426 | void cd_forget(struct inode *inode) |
| 427 | { |
| 428 | spin_lock(&cdev_lock); |
| 429 | list_del_init(&inode->i_devices); |
| 430 | inode->i_cdev = NULL; |
| 431 | inode->i_mapping = &inode->i_data; |
| 432 | spin_unlock(&cdev_lock); |
| 433 | } |
| 434 | |
| 435 | static void cdev_purge(struct cdev *cdev) |
| 436 | { |
| 437 | spin_lock(&cdev_lock); |
| 438 | while (!list_empty(&cdev->list)) { |
| 439 | struct inode *inode; |
| 440 | inode = container_of(cdev->list.next, struct inode, i_devices); |
| 441 | list_del_init(&inode->i_devices); |
| 442 | inode->i_cdev = NULL; |
| 443 | } |
| 444 | spin_unlock(&cdev_lock); |
| 445 | } |
| 446 | |
| 447 | /* |
| 448 | * Dummy default file-operations: the only thing this does |
| 449 | * is contain the open that then fills in the correct operations |
| 450 | * depending on the special file... |
| 451 | */ |
| 452 | const struct file_operations def_chr_fops = { |
| 453 | .open = chrdev_open, |
| 454 | .llseek = noop_llseek, |
| 455 | }; |
| 456 | |
| 457 | static struct kobject *exact_match(dev_t dev, int *part, void *data) |
| 458 | { |
| 459 | struct cdev *p = data; |
| 460 | return &p->kobj; |
| 461 | } |
| 462 | |
| 463 | static int exact_lock(dev_t dev, void *data) |
| 464 | { |
| 465 | struct cdev *p = data; |
| 466 | return cdev_get(p) ? 0 : -1; |
| 467 | } |
| 468 | |
| 469 | /** |
| 470 | * cdev_add() - add a char device to the system |
| 471 | * @p: the cdev structure for the device |
| 472 | * @dev: the first device number for which this device is responsible |
| 473 | * @count: the number of consecutive minor numbers corresponding to this |
| 474 | * device |
| 475 | * |
| 476 | * cdev_add() adds the device represented by @p to the system, making it |
| 477 | * live immediately. A negative error code is returned on failure. |
| 478 | */ |
| 479 | int cdev_add(struct cdev *p, dev_t dev, unsigned count) |
| 480 | { |
| 481 | int error; |
| 482 | |
| 483 | p->dev = dev; |
| 484 | p->count = count; |
| 485 | |
| 486 | if (WARN_ON(dev == WHITEOUT_DEV)) { |
| 487 | error = -EBUSY; |
| 488 | goto err; |
| 489 | } |
| 490 | |
| 491 | error = kobj_map(cdev_map, dev, count, NULL, |
| 492 | exact_match, exact_lock, p); |
| 493 | if (error) |
| 494 | goto err; |
| 495 | |
| 496 | kobject_get(p->kobj.parent); |
| 497 | |
| 498 | return 0; |
| 499 | |
| 500 | err: |
| 501 | kfree_const(p->kobj.name); |
| 502 | p->kobj.name = NULL; |
| 503 | return error; |
| 504 | } |
| 505 | |
| 506 | /** |
| 507 | * cdev_set_parent() - set the parent kobject for a char device |
| 508 | * @p: the cdev structure |
| 509 | * @kobj: the kobject to take a reference to |
| 510 | * |
| 511 | * cdev_set_parent() sets a parent kobject which will be referenced |
| 512 | * appropriately so the parent is not freed before the cdev. This |
| 513 | * should be called before cdev_add. |
| 514 | */ |
| 515 | void cdev_set_parent(struct cdev *p, struct kobject *kobj) |
| 516 | { |
| 517 | WARN_ON(!kobj->state_initialized); |
| 518 | p->kobj.parent = kobj; |
| 519 | } |
| 520 | |
| 521 | /** |
| 522 | * cdev_device_add() - add a char device and it's corresponding |
| 523 | * struct device, linkink |
| 524 | * @dev: the device structure |
| 525 | * @cdev: the cdev structure |
| 526 | * |
| 527 | * cdev_device_add() adds the char device represented by @cdev to the system, |
| 528 | * just as cdev_add does. It then adds @dev to the system using device_add |
| 529 | * The dev_t for the char device will be taken from the struct device which |
| 530 | * needs to be initialized first. This helper function correctly takes a |
| 531 | * reference to the parent device so the parent will not get released until |
| 532 | * all references to the cdev are released. |
| 533 | * |
| 534 | * This helper uses dev->devt for the device number. If it is not set |
| 535 | * it will not add the cdev and it will be equivalent to device_add. |
| 536 | * |
| 537 | * This function should be used whenever the struct cdev and the |
| 538 | * struct device are members of the same structure whose lifetime is |
| 539 | * managed by the struct device. |
| 540 | * |
| 541 | * NOTE: Callers must assume that userspace was able to open the cdev and |
| 542 | * can call cdev fops callbacks at any time, even if this function fails. |
| 543 | */ |
| 544 | int cdev_device_add(struct cdev *cdev, struct device *dev) |
| 545 | { |
| 546 | int rc = 0; |
| 547 | |
| 548 | if (dev->devt) { |
| 549 | cdev_set_parent(cdev, &dev->kobj); |
| 550 | |
| 551 | rc = cdev_add(cdev, dev->devt, 1); |
| 552 | if (rc) |
| 553 | return rc; |
| 554 | } |
| 555 | |
| 556 | rc = device_add(dev); |
| 557 | if (rc && dev->devt) |
| 558 | cdev_del(cdev); |
| 559 | |
| 560 | return rc; |
| 561 | } |
| 562 | |
| 563 | /** |
| 564 | * cdev_device_del() - inverse of cdev_device_add |
| 565 | * @dev: the device structure |
| 566 | * @cdev: the cdev structure |
| 567 | * |
| 568 | * cdev_device_del() is a helper function to call cdev_del and device_del. |
| 569 | * It should be used whenever cdev_device_add is used. |
| 570 | * |
| 571 | * If dev->devt is not set it will not remove the cdev and will be equivalent |
| 572 | * to device_del. |
| 573 | * |
| 574 | * NOTE: This guarantees that associated sysfs callbacks are not running |
| 575 | * or runnable, however any cdevs already open will remain and their fops |
| 576 | * will still be callable even after this function returns. |
| 577 | */ |
| 578 | void cdev_device_del(struct cdev *cdev, struct device *dev) |
| 579 | { |
| 580 | device_del(dev); |
| 581 | if (dev->devt) |
| 582 | cdev_del(cdev); |
| 583 | } |
| 584 | |
| 585 | static void cdev_unmap(dev_t dev, unsigned count) |
| 586 | { |
| 587 | kobj_unmap(cdev_map, dev, count); |
| 588 | } |
| 589 | |
| 590 | /** |
| 591 | * cdev_del() - remove a cdev from the system |
| 592 | * @p: the cdev structure to be removed |
| 593 | * |
| 594 | * cdev_del() removes @p from the system, possibly freeing the structure |
| 595 | * itself. |
| 596 | * |
| 597 | * NOTE: This guarantees that cdev device will no longer be able to be |
| 598 | * opened, however any cdevs already open will remain and their fops will |
| 599 | * still be callable even after cdev_del returns. |
| 600 | */ |
| 601 | void cdev_del(struct cdev *p) |
| 602 | { |
| 603 | cdev_unmap(p->dev, p->count); |
| 604 | kobject_put(&p->kobj); |
| 605 | } |
| 606 | |
| 607 | |
| 608 | static void cdev_default_release(struct kobject *kobj) |
| 609 | { |
| 610 | struct cdev *p = container_of(kobj, struct cdev, kobj); |
| 611 | struct kobject *parent = kobj->parent; |
| 612 | |
| 613 | cdev_purge(p); |
| 614 | kobject_put(parent); |
| 615 | } |
| 616 | |
| 617 | static void cdev_dynamic_release(struct kobject *kobj) |
| 618 | { |
| 619 | struct cdev *p = container_of(kobj, struct cdev, kobj); |
| 620 | struct kobject *parent = kobj->parent; |
| 621 | |
| 622 | cdev_purge(p); |
| 623 | kfree(p); |
| 624 | kobject_put(parent); |
| 625 | } |
| 626 | |
| 627 | static struct kobj_type ktype_cdev_default = { |
| 628 | .release = cdev_default_release, |
| 629 | }; |
| 630 | |
| 631 | static struct kobj_type ktype_cdev_dynamic = { |
| 632 | .release = cdev_dynamic_release, |
| 633 | }; |
| 634 | |
| 635 | /** |
| 636 | * cdev_alloc() - allocate a cdev structure |
| 637 | * |
| 638 | * Allocates and returns a cdev structure, or NULL on failure. |
| 639 | */ |
| 640 | struct cdev *cdev_alloc(void) |
| 641 | { |
| 642 | struct cdev *p = kzalloc(sizeof(struct cdev), GFP_KERNEL); |
| 643 | if (p) { |
| 644 | INIT_LIST_HEAD(&p->list); |
| 645 | kobject_init(&p->kobj, &ktype_cdev_dynamic); |
| 646 | } |
| 647 | return p; |
| 648 | } |
| 649 | |
| 650 | /** |
| 651 | * cdev_init() - initialize a cdev structure |
| 652 | * @cdev: the structure to initialize |
| 653 | * @fops: the file_operations for this device |
| 654 | * |
| 655 | * Initializes @cdev, remembering @fops, making it ready to add to the |
| 656 | * system with cdev_add(). |
| 657 | */ |
| 658 | void cdev_init(struct cdev *cdev, const struct file_operations *fops) |
| 659 | { |
| 660 | memset(cdev, 0, sizeof *cdev); |
| 661 | INIT_LIST_HEAD(&cdev->list); |
| 662 | kobject_init(&cdev->kobj, &ktype_cdev_default); |
| 663 | cdev->ops = fops; |
| 664 | } |
| 665 | |
| 666 | static struct kobject *base_probe(dev_t dev, int *part, void *data) |
| 667 | { |
| 668 | if (request_module("char-major-%d-%d", MAJOR(dev), MINOR(dev)) > 0) |
| 669 | /* Make old-style 2.4 aliases work */ |
| 670 | request_module("char-major-%d", MAJOR(dev)); |
| 671 | return NULL; |
| 672 | } |
| 673 | |
| 674 | void __init chrdev_init(void) |
| 675 | { |
| 676 | cdev_map = kobj_map_init(base_probe, &chrdevs_lock); |
| 677 | } |
| 678 | |
| 679 | |
| 680 | /* Let modules do char dev stuff */ |
| 681 | EXPORT_SYMBOL(register_chrdev_region); |
| 682 | EXPORT_SYMBOL(unregister_chrdev_region); |
| 683 | EXPORT_SYMBOL(alloc_chrdev_region); |
| 684 | EXPORT_SYMBOL(cdev_init); |
| 685 | EXPORT_SYMBOL(cdev_alloc); |
| 686 | EXPORT_SYMBOL(cdev_del); |
| 687 | EXPORT_SYMBOL(cdev_add); |
| 688 | EXPORT_SYMBOL(cdev_set_parent); |
| 689 | EXPORT_SYMBOL(cdev_device_add); |
| 690 | EXPORT_SYMBOL(cdev_device_del); |
| 691 | EXPORT_SYMBOL(__register_chrdev); |
| 692 | EXPORT_SYMBOL(__unregister_chrdev); |