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cdae7c07 MW |
1 | /* |
2 | * Thunderbolt XDomain property support | |
3 | * | |
4 | * Copyright (C) 2017, Intel Corporation | |
5 | * Authors: Michael Jamet <michael.jamet@intel.com> | |
6 | * Mika Westerberg <mika.westerberg@linux.intel.com> | |
7 | * | |
8 | * This program is free software; you can redistribute it and/or modify | |
9 | * it under the terms of the GNU General Public License version 2 as | |
10 | * published by the Free Software Foundation. | |
11 | */ | |
12 | ||
13 | #include <linux/err.h> | |
14 | #include <linux/slab.h> | |
15 | #include <linux/string.h> | |
16 | #include <linux/uuid.h> | |
17 | #include <linux/thunderbolt.h> | |
18 | ||
19 | struct tb_property_entry { | |
20 | u32 key_hi; | |
21 | u32 key_lo; | |
22 | u16 length; | |
23 | u8 reserved; | |
24 | u8 type; | |
25 | u32 value; | |
26 | }; | |
27 | ||
28 | struct tb_property_rootdir_entry { | |
29 | u32 magic; | |
30 | u32 length; | |
31 | struct tb_property_entry entries[]; | |
32 | }; | |
33 | ||
34 | struct tb_property_dir_entry { | |
35 | u32 uuid[4]; | |
36 | struct tb_property_entry entries[]; | |
37 | }; | |
38 | ||
39 | #define TB_PROPERTY_ROOTDIR_MAGIC 0x55584401 | |
40 | ||
41 | static struct tb_property_dir *__tb_property_parse_dir(const u32 *block, | |
42 | size_t block_len, unsigned int dir_offset, size_t dir_len, | |
43 | bool is_root); | |
44 | ||
45 | static inline void parse_dwdata(void *dst, const void *src, size_t dwords) | |
46 | { | |
47 | be32_to_cpu_array(dst, src, dwords); | |
48 | } | |
49 | ||
50 | static inline void format_dwdata(void *dst, const void *src, size_t dwords) | |
51 | { | |
52 | cpu_to_be32_array(dst, src, dwords); | |
53 | } | |
54 | ||
55 | static bool tb_property_entry_valid(const struct tb_property_entry *entry, | |
56 | size_t block_len) | |
57 | { | |
58 | switch (entry->type) { | |
59 | case TB_PROPERTY_TYPE_DIRECTORY: | |
60 | case TB_PROPERTY_TYPE_DATA: | |
61 | case TB_PROPERTY_TYPE_TEXT: | |
62 | if (entry->length > block_len) | |
63 | return false; | |
64 | if (entry->value + entry->length > block_len) | |
65 | return false; | |
66 | break; | |
67 | ||
68 | case TB_PROPERTY_TYPE_VALUE: | |
69 | if (entry->length != 1) | |
70 | return false; | |
71 | break; | |
72 | } | |
73 | ||
74 | return true; | |
75 | } | |
76 | ||
77 | static bool tb_property_key_valid(const char *key) | |
78 | { | |
79 | return key && strlen(key) <= TB_PROPERTY_KEY_SIZE; | |
80 | } | |
81 | ||
82 | static struct tb_property * | |
83 | tb_property_alloc(const char *key, enum tb_property_type type) | |
84 | { | |
85 | struct tb_property *property; | |
86 | ||
87 | property = kzalloc(sizeof(*property), GFP_KERNEL); | |
88 | if (!property) | |
89 | return NULL; | |
90 | ||
91 | strcpy(property->key, key); | |
92 | property->type = type; | |
93 | INIT_LIST_HEAD(&property->list); | |
94 | ||
95 | return property; | |
96 | } | |
97 | ||
98 | static struct tb_property *tb_property_parse(const u32 *block, size_t block_len, | |
99 | const struct tb_property_entry *entry) | |
100 | { | |
101 | char key[TB_PROPERTY_KEY_SIZE + 1]; | |
102 | struct tb_property *property; | |
103 | struct tb_property_dir *dir; | |
104 | ||
105 | if (!tb_property_entry_valid(entry, block_len)) | |
106 | return NULL; | |
107 | ||
108 | parse_dwdata(key, entry, 2); | |
109 | key[TB_PROPERTY_KEY_SIZE] = '\0'; | |
110 | ||
111 | property = tb_property_alloc(key, entry->type); | |
112 | if (!property) | |
113 | return NULL; | |
114 | ||
115 | property->length = entry->length; | |
116 | ||
117 | switch (property->type) { | |
118 | case TB_PROPERTY_TYPE_DIRECTORY: | |
119 | dir = __tb_property_parse_dir(block, block_len, entry->value, | |
120 | entry->length, false); | |
121 | if (!dir) { | |
122 | kfree(property); | |
123 | return NULL; | |
124 | } | |
125 | property->value.dir = dir; | |
126 | break; | |
127 | ||
128 | case TB_PROPERTY_TYPE_DATA: | |
129 | property->value.data = kcalloc(property->length, sizeof(u32), | |
130 | GFP_KERNEL); | |
131 | if (!property->value.data) { | |
132 | kfree(property); | |
133 | return NULL; | |
134 | } | |
135 | parse_dwdata(property->value.data, block + entry->value, | |
136 | entry->length); | |
137 | break; | |
138 | ||
139 | case TB_PROPERTY_TYPE_TEXT: | |
140 | property->value.text = kcalloc(property->length, sizeof(u32), | |
141 | GFP_KERNEL); | |
142 | if (!property->value.text) { | |
143 | kfree(property); | |
144 | return NULL; | |
145 | } | |
146 | parse_dwdata(property->value.text, block + entry->value, | |
147 | entry->length); | |
148 | /* Force null termination */ | |
149 | property->value.text[property->length * 4 - 1] = '\0'; | |
150 | break; | |
151 | ||
152 | case TB_PROPERTY_TYPE_VALUE: | |
153 | property->value.immediate = entry->value; | |
154 | break; | |
155 | ||
156 | default: | |
157 | property->type = TB_PROPERTY_TYPE_UNKNOWN; | |
158 | break; | |
159 | } | |
160 | ||
161 | return property; | |
162 | } | |
163 | ||
164 | static struct tb_property_dir *__tb_property_parse_dir(const u32 *block, | |
165 | size_t block_len, unsigned int dir_offset, size_t dir_len, bool is_root) | |
166 | { | |
167 | const struct tb_property_entry *entries; | |
168 | size_t i, content_len, nentries; | |
169 | unsigned int content_offset; | |
170 | struct tb_property_dir *dir; | |
171 | ||
172 | dir = kzalloc(sizeof(*dir), GFP_KERNEL); | |
173 | if (!dir) | |
174 | return NULL; | |
175 | ||
176 | if (is_root) { | |
177 | content_offset = dir_offset + 2; | |
178 | content_len = dir_len; | |
179 | } else { | |
180 | dir->uuid = kmemdup(&block[dir_offset], sizeof(*dir->uuid), | |
181 | GFP_KERNEL); | |
182 | content_offset = dir_offset + 4; | |
183 | content_len = dir_len - 4; /* Length includes UUID */ | |
184 | } | |
185 | ||
186 | entries = (const struct tb_property_entry *)&block[content_offset]; | |
187 | nentries = content_len / (sizeof(*entries) / 4); | |
188 | ||
189 | INIT_LIST_HEAD(&dir->properties); | |
190 | ||
191 | for (i = 0; i < nentries; i++) { | |
192 | struct tb_property *property; | |
193 | ||
194 | property = tb_property_parse(block, block_len, &entries[i]); | |
195 | if (!property) { | |
196 | tb_property_free_dir(dir); | |
197 | return NULL; | |
198 | } | |
199 | ||
200 | list_add_tail(&property->list, &dir->properties); | |
201 | } | |
202 | ||
203 | return dir; | |
204 | } | |
205 | ||
206 | /** | |
207 | * tb_property_parse_dir() - Parses properties from given property block | |
208 | * @block: Property block to parse | |
209 | * @block_len: Number of dword elements in the property block | |
210 | * | |
211 | * This function parses the XDomain properties data block into format that | |
212 | * can be traversed using the helper functions provided by this module. | |
213 | * Upon success returns the parsed directory. In case of error returns | |
214 | * %NULL. The resulting &struct tb_property_dir needs to be released by | |
215 | * calling tb_property_free_dir() when not needed anymore. | |
216 | * | |
217 | * The @block is expected to be root directory. | |
218 | */ | |
219 | struct tb_property_dir *tb_property_parse_dir(const u32 *block, | |
220 | size_t block_len) | |
221 | { | |
222 | const struct tb_property_rootdir_entry *rootdir = | |
223 | (const struct tb_property_rootdir_entry *)block; | |
224 | ||
225 | if (rootdir->magic != TB_PROPERTY_ROOTDIR_MAGIC) | |
226 | return NULL; | |
227 | if (rootdir->length > block_len) | |
228 | return NULL; | |
229 | ||
230 | return __tb_property_parse_dir(block, block_len, 0, rootdir->length, | |
231 | true); | |
232 | } | |
233 | ||
234 | /** | |
235 | * tb_property_create_dir() - Creates new property directory | |
236 | * @uuid: UUID used to identify the particular directory | |
237 | * | |
238 | * Creates new, empty property directory. If @uuid is %NULL then the | |
239 | * directory is assumed to be root directory. | |
240 | */ | |
241 | struct tb_property_dir *tb_property_create_dir(const uuid_t *uuid) | |
242 | { | |
243 | struct tb_property_dir *dir; | |
244 | ||
245 | dir = kzalloc(sizeof(*dir), GFP_KERNEL); | |
246 | if (!dir) | |
247 | return NULL; | |
248 | ||
249 | INIT_LIST_HEAD(&dir->properties); | |
250 | if (uuid) { | |
251 | dir->uuid = kmemdup(uuid, sizeof(*dir->uuid), GFP_KERNEL); | |
252 | if (!dir->uuid) { | |
253 | kfree(dir); | |
254 | return NULL; | |
255 | } | |
256 | } | |
257 | ||
258 | return dir; | |
259 | } | |
260 | EXPORT_SYMBOL_GPL(tb_property_create_dir); | |
261 | ||
262 | static void tb_property_free(struct tb_property *property) | |
263 | { | |
264 | switch (property->type) { | |
265 | case TB_PROPERTY_TYPE_DIRECTORY: | |
266 | tb_property_free_dir(property->value.dir); | |
267 | break; | |
268 | ||
269 | case TB_PROPERTY_TYPE_DATA: | |
270 | kfree(property->value.data); | |
271 | break; | |
272 | ||
273 | case TB_PROPERTY_TYPE_TEXT: | |
274 | kfree(property->value.text); | |
275 | break; | |
276 | ||
277 | default: | |
278 | break; | |
279 | } | |
280 | ||
281 | kfree(property); | |
282 | } | |
283 | ||
284 | /** | |
285 | * tb_property_free_dir() - Release memory allocated for property directory | |
286 | * @dir: Directory to release | |
287 | * | |
288 | * This will release all the memory the directory occupies including all | |
289 | * descendants. It is OK to pass %NULL @dir, then the function does | |
290 | * nothing. | |
291 | */ | |
292 | void tb_property_free_dir(struct tb_property_dir *dir) | |
293 | { | |
294 | struct tb_property *property, *tmp; | |
295 | ||
296 | if (!dir) | |
297 | return; | |
298 | ||
299 | list_for_each_entry_safe(property, tmp, &dir->properties, list) { | |
300 | list_del(&property->list); | |
301 | tb_property_free(property); | |
302 | } | |
303 | kfree(dir->uuid); | |
304 | kfree(dir); | |
305 | } | |
306 | EXPORT_SYMBOL_GPL(tb_property_free_dir); | |
307 | ||
308 | static size_t tb_property_dir_length(const struct tb_property_dir *dir, | |
309 | bool recurse, size_t *data_len) | |
310 | { | |
311 | const struct tb_property *property; | |
312 | size_t len = 0; | |
313 | ||
314 | if (dir->uuid) | |
315 | len += sizeof(*dir->uuid) / 4; | |
316 | else | |
317 | len += sizeof(struct tb_property_rootdir_entry) / 4; | |
318 | ||
319 | list_for_each_entry(property, &dir->properties, list) { | |
320 | len += sizeof(struct tb_property_entry) / 4; | |
321 | ||
322 | switch (property->type) { | |
323 | case TB_PROPERTY_TYPE_DIRECTORY: | |
324 | if (recurse) { | |
325 | len += tb_property_dir_length( | |
326 | property->value.dir, recurse, data_len); | |
327 | } | |
328 | /* Reserve dword padding after each directory */ | |
329 | if (data_len) | |
330 | *data_len += 1; | |
331 | break; | |
332 | ||
333 | case TB_PROPERTY_TYPE_DATA: | |
334 | case TB_PROPERTY_TYPE_TEXT: | |
335 | if (data_len) | |
336 | *data_len += property->length; | |
337 | break; | |
338 | ||
339 | default: | |
340 | break; | |
341 | } | |
342 | } | |
343 | ||
344 | return len; | |
345 | } | |
346 | ||
347 | static ssize_t __tb_property_format_dir(const struct tb_property_dir *dir, | |
348 | u32 *block, unsigned int start_offset, size_t block_len) | |
349 | { | |
350 | unsigned int data_offset, dir_end; | |
351 | const struct tb_property *property; | |
352 | struct tb_property_entry *entry; | |
353 | size_t dir_len, data_len = 0; | |
354 | int ret; | |
355 | ||
356 | /* | |
357 | * The structure of property block looks like following. Leaf | |
358 | * data/text is included right after the directory and each | |
359 | * directory follows each other (even nested ones). | |
360 | * | |
361 | * +----------+ <-- start_offset | |
362 | * | header | <-- root directory header | |
363 | * +----------+ --- | |
364 | * | entry 0 | -^--------------------. | |
365 | * +----------+ | | | |
366 | * | entry 1 | -|--------------------|--. | |
367 | * +----------+ | | | | |
368 | * | entry 2 | -|-----------------. | | | |
369 | * +----------+ | | | | | |
370 | * : : | dir_len | | | | |
371 | * . . | | | | | |
372 | * : : | | | | | |
373 | * +----------+ | | | | | |
374 | * | entry n | v | | | | |
375 | * +----------+ <-- data_offset | | | | |
376 | * | data 0 | <------------------|--' | | |
377 | * +----------+ | | | |
378 | * | data 1 | <------------------|-----' | |
379 | * +----------+ | | |
380 | * | 00000000 | padding | | |
381 | * +----------+ <-- dir_end <------' | |
382 | * | UUID | <-- directory UUID (child directory) | |
383 | * +----------+ | |
384 | * | entry 0 | | |
385 | * +----------+ | |
386 | * | entry 1 | | |
387 | * +----------+ | |
388 | * : : | |
389 | * . . | |
390 | * : : | |
391 | * +----------+ | |
392 | * | entry n | | |
393 | * +----------+ | |
394 | * | data 0 | | |
395 | * +----------+ | |
396 | * | |
397 | * We use dir_end to hold pointer to the end of the directory. It | |
398 | * will increase as we add directories and each directory should be | |
399 | * added starting from previous dir_end. | |
400 | */ | |
401 | dir_len = tb_property_dir_length(dir, false, &data_len); | |
402 | data_offset = start_offset + dir_len; | |
403 | dir_end = start_offset + data_len + dir_len; | |
404 | ||
405 | if (data_offset > dir_end) | |
406 | return -EINVAL; | |
407 | if (dir_end > block_len) | |
408 | return -EINVAL; | |
409 | ||
410 | /* Write headers first */ | |
411 | if (dir->uuid) { | |
412 | struct tb_property_dir_entry *pe; | |
413 | ||
414 | pe = (struct tb_property_dir_entry *)&block[start_offset]; | |
415 | memcpy(pe->uuid, dir->uuid, sizeof(pe->uuid)); | |
416 | entry = pe->entries; | |
417 | } else { | |
418 | struct tb_property_rootdir_entry *re; | |
419 | ||
420 | re = (struct tb_property_rootdir_entry *)&block[start_offset]; | |
421 | re->magic = TB_PROPERTY_ROOTDIR_MAGIC; | |
422 | re->length = dir_len - sizeof(*re) / 4; | |
423 | entry = re->entries; | |
424 | } | |
425 | ||
426 | list_for_each_entry(property, &dir->properties, list) { | |
427 | const struct tb_property_dir *child; | |
428 | ||
429 | format_dwdata(entry, property->key, 2); | |
430 | entry->type = property->type; | |
431 | ||
432 | switch (property->type) { | |
433 | case TB_PROPERTY_TYPE_DIRECTORY: | |
434 | child = property->value.dir; | |
435 | ret = __tb_property_format_dir(child, block, dir_end, | |
436 | block_len); | |
437 | if (ret < 0) | |
438 | return ret; | |
439 | entry->length = tb_property_dir_length(child, false, | |
440 | NULL); | |
441 | entry->value = dir_end; | |
442 | dir_end = ret; | |
443 | break; | |
444 | ||
445 | case TB_PROPERTY_TYPE_DATA: | |
446 | format_dwdata(&block[data_offset], property->value.data, | |
447 | property->length); | |
448 | entry->length = property->length; | |
449 | entry->value = data_offset; | |
450 | data_offset += entry->length; | |
451 | break; | |
452 | ||
453 | case TB_PROPERTY_TYPE_TEXT: | |
454 | format_dwdata(&block[data_offset], property->value.text, | |
455 | property->length); | |
456 | entry->length = property->length; | |
457 | entry->value = data_offset; | |
458 | data_offset += entry->length; | |
459 | break; | |
460 | ||
461 | case TB_PROPERTY_TYPE_VALUE: | |
462 | entry->length = property->length; | |
463 | entry->value = property->value.immediate; | |
464 | break; | |
465 | ||
466 | default: | |
467 | break; | |
468 | } | |
469 | ||
470 | entry++; | |
471 | } | |
472 | ||
473 | return dir_end; | |
474 | } | |
475 | ||
476 | /** | |
477 | * tb_property_format_dir() - Formats directory to the packed XDomain format | |
478 | * @dir: Directory to format | |
479 | * @block: Property block where the packed data is placed | |
480 | * @block_len: Length of the property block | |
481 | * | |
482 | * This function formats the directory to the packed format that can be | |
483 | * then send over the thunderbolt fabric to receiving host. Returns %0 in | |
484 | * case of success and negative errno on faulure. Passing %NULL in @block | |
485 | * returns number of entries the block takes. | |
486 | */ | |
487 | ssize_t tb_property_format_dir(const struct tb_property_dir *dir, u32 *block, | |
488 | size_t block_len) | |
489 | { | |
490 | ssize_t ret; | |
491 | ||
492 | if (!block) { | |
493 | size_t dir_len, data_len = 0; | |
494 | ||
495 | dir_len = tb_property_dir_length(dir, true, &data_len); | |
496 | return dir_len + data_len; | |
497 | } | |
498 | ||
499 | ret = __tb_property_format_dir(dir, block, 0, block_len); | |
500 | return ret < 0 ? ret : 0; | |
501 | } | |
502 | ||
503 | /** | |
504 | * tb_property_add_immediate() - Add immediate property to directory | |
505 | * @parent: Directory to add the property | |
506 | * @key: Key for the property | |
507 | * @value: Immediate value to store with the property | |
508 | */ | |
509 | int tb_property_add_immediate(struct tb_property_dir *parent, const char *key, | |
510 | u32 value) | |
511 | { | |
512 | struct tb_property *property; | |
513 | ||
514 | if (!tb_property_key_valid(key)) | |
515 | return -EINVAL; | |
516 | ||
517 | property = tb_property_alloc(key, TB_PROPERTY_TYPE_VALUE); | |
518 | if (!property) | |
519 | return -ENOMEM; | |
520 | ||
521 | property->length = 1; | |
522 | property->value.immediate = value; | |
523 | ||
524 | list_add_tail(&property->list, &parent->properties); | |
525 | return 0; | |
526 | } | |
527 | EXPORT_SYMBOL_GPL(tb_property_add_immediate); | |
528 | ||
529 | /** | |
530 | * tb_property_add_data() - Adds arbitrary data property to directory | |
531 | * @parent: Directory to add the property | |
532 | * @key: Key for the property | |
533 | * @buf: Data buffer to add | |
534 | * @buflen: Number of bytes in the data buffer | |
535 | * | |
536 | * Function takes a copy of @buf and adds it to the directory. | |
537 | */ | |
538 | int tb_property_add_data(struct tb_property_dir *parent, const char *key, | |
539 | const void *buf, size_t buflen) | |
540 | { | |
541 | /* Need to pad to dword boundary */ | |
542 | size_t size = round_up(buflen, 4); | |
543 | struct tb_property *property; | |
544 | ||
545 | if (!tb_property_key_valid(key)) | |
546 | return -EINVAL; | |
547 | ||
548 | property = tb_property_alloc(key, TB_PROPERTY_TYPE_DATA); | |
549 | if (!property) | |
550 | return -ENOMEM; | |
551 | ||
552 | property->length = size / 4; | |
553 | property->value.data = kzalloc(size, GFP_KERNEL); | |
554 | memcpy(property->value.data, buf, buflen); | |
555 | ||
556 | list_add_tail(&property->list, &parent->properties); | |
557 | return 0; | |
558 | } | |
559 | EXPORT_SYMBOL_GPL(tb_property_add_data); | |
560 | ||
561 | /** | |
562 | * tb_property_add_text() - Adds string property to directory | |
563 | * @parent: Directory to add the property | |
564 | * @key: Key for the property | |
565 | * @text: String to add | |
566 | * | |
567 | * Function takes a copy of @text and adds it to the directory. | |
568 | */ | |
569 | int tb_property_add_text(struct tb_property_dir *parent, const char *key, | |
570 | const char *text) | |
571 | { | |
572 | /* Need to pad to dword boundary */ | |
573 | size_t size = round_up(strlen(text) + 1, 4); | |
574 | struct tb_property *property; | |
575 | ||
576 | if (!tb_property_key_valid(key)) | |
577 | return -EINVAL; | |
578 | ||
579 | property = tb_property_alloc(key, TB_PROPERTY_TYPE_TEXT); | |
580 | if (!property) | |
581 | return -ENOMEM; | |
582 | ||
583 | property->length = size / 4; | |
584 | property->value.data = kzalloc(size, GFP_KERNEL); | |
585 | strcpy(property->value.text, text); | |
586 | ||
587 | list_add_tail(&property->list, &parent->properties); | |
588 | return 0; | |
589 | } | |
590 | EXPORT_SYMBOL_GPL(tb_property_add_text); | |
591 | ||
592 | /** | |
593 | * tb_property_add_dir() - Adds a directory to the parent directory | |
594 | * @parent: Directory to add the property | |
595 | * @key: Key for the property | |
596 | * @dir: Directory to add | |
597 | */ | |
598 | int tb_property_add_dir(struct tb_property_dir *parent, const char *key, | |
599 | struct tb_property_dir *dir) | |
600 | { | |
601 | struct tb_property *property; | |
602 | ||
603 | if (!tb_property_key_valid(key)) | |
604 | return -EINVAL; | |
605 | ||
606 | property = tb_property_alloc(key, TB_PROPERTY_TYPE_DIRECTORY); | |
607 | if (!property) | |
608 | return -ENOMEM; | |
609 | ||
610 | property->value.dir = dir; | |
611 | ||
612 | list_add_tail(&property->list, &parent->properties); | |
613 | return 0; | |
614 | } | |
615 | EXPORT_SYMBOL_GPL(tb_property_add_dir); | |
616 | ||
617 | /** | |
618 | * tb_property_remove() - Removes property from a parent directory | |
619 | * @property: Property to remove | |
620 | * | |
621 | * Note memory for @property is released as well so it is not allowed to | |
622 | * touch the object after call to this function. | |
623 | */ | |
624 | void tb_property_remove(struct tb_property *property) | |
625 | { | |
626 | list_del(&property->list); | |
627 | kfree(property); | |
628 | } | |
629 | EXPORT_SYMBOL_GPL(tb_property_remove); | |
630 | ||
631 | /** | |
632 | * tb_property_find() - Find a property from a directory | |
633 | * @dir: Directory where the property is searched | |
634 | * @key: Key to look for | |
635 | * @type: Type of the property | |
636 | * | |
637 | * Finds and returns property from the given directory. Does not recurse | |
638 | * into sub-directories. Returns %NULL if the property was not found. | |
639 | */ | |
640 | struct tb_property *tb_property_find(struct tb_property_dir *dir, | |
641 | const char *key, enum tb_property_type type) | |
642 | { | |
643 | struct tb_property *property; | |
644 | ||
645 | list_for_each_entry(property, &dir->properties, list) { | |
646 | if (property->type == type && !strcmp(property->key, key)) | |
647 | return property; | |
648 | } | |
649 | ||
650 | return NULL; | |
651 | } | |
652 | EXPORT_SYMBOL_GPL(tb_property_find); | |
653 | ||
654 | /** | |
655 | * tb_property_get_next() - Get next property from directory | |
656 | * @dir: Directory holding properties | |
657 | * @prev: Previous property in the directory (%NULL returns the first) | |
658 | */ | |
659 | struct tb_property *tb_property_get_next(struct tb_property_dir *dir, | |
660 | struct tb_property *prev) | |
661 | { | |
662 | if (prev) { | |
663 | if (list_is_last(&prev->list, &dir->properties)) | |
664 | return NULL; | |
665 | return list_next_entry(prev, list); | |
666 | } | |
667 | return list_first_entry_or_null(&dir->properties, struct tb_property, | |
668 | list); | |
669 | } | |
670 | EXPORT_SYMBOL_GPL(tb_property_get_next); |