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fd3b339c | 1 | // SPDX-License-Identifier: GPL-2.0 |
cdae7c07 MW |
2 | /* |
3 | * Thunderbolt XDomain property support | |
4 | * | |
5 | * Copyright (C) 2017, Intel Corporation | |
6 | * Authors: Michael Jamet <michael.jamet@intel.com> | |
7 | * Mika Westerberg <mika.westerberg@linux.intel.com> | |
cdae7c07 MW |
8 | */ |
9 | ||
10 | #include <linux/err.h> | |
11 | #include <linux/slab.h> | |
12 | #include <linux/string.h> | |
13 | #include <linux/uuid.h> | |
14 | #include <linux/thunderbolt.h> | |
15 | ||
16 | struct tb_property_entry { | |
17 | u32 key_hi; | |
18 | u32 key_lo; | |
19 | u16 length; | |
20 | u8 reserved; | |
21 | u8 type; | |
22 | u32 value; | |
23 | }; | |
24 | ||
25 | struct tb_property_rootdir_entry { | |
26 | u32 magic; | |
27 | u32 length; | |
28 | struct tb_property_entry entries[]; | |
29 | }; | |
30 | ||
31 | struct tb_property_dir_entry { | |
32 | u32 uuid[4]; | |
33 | struct tb_property_entry entries[]; | |
34 | }; | |
35 | ||
36 | #define TB_PROPERTY_ROOTDIR_MAGIC 0x55584401 | |
37 | ||
38 | static struct tb_property_dir *__tb_property_parse_dir(const u32 *block, | |
39 | size_t block_len, unsigned int dir_offset, size_t dir_len, | |
40 | bool is_root); | |
41 | ||
42 | static inline void parse_dwdata(void *dst, const void *src, size_t dwords) | |
43 | { | |
44 | be32_to_cpu_array(dst, src, dwords); | |
45 | } | |
46 | ||
47 | static inline void format_dwdata(void *dst, const void *src, size_t dwords) | |
48 | { | |
49 | cpu_to_be32_array(dst, src, dwords); | |
50 | } | |
51 | ||
52 | static bool tb_property_entry_valid(const struct tb_property_entry *entry, | |
53 | size_t block_len) | |
54 | { | |
55 | switch (entry->type) { | |
56 | case TB_PROPERTY_TYPE_DIRECTORY: | |
57 | case TB_PROPERTY_TYPE_DATA: | |
58 | case TB_PROPERTY_TYPE_TEXT: | |
59 | if (entry->length > block_len) | |
60 | return false; | |
61 | if (entry->value + entry->length > block_len) | |
62 | return false; | |
63 | break; | |
64 | ||
65 | case TB_PROPERTY_TYPE_VALUE: | |
66 | if (entry->length != 1) | |
67 | return false; | |
68 | break; | |
69 | } | |
70 | ||
71 | return true; | |
72 | } | |
73 | ||
74 | static bool tb_property_key_valid(const char *key) | |
75 | { | |
76 | return key && strlen(key) <= TB_PROPERTY_KEY_SIZE; | |
77 | } | |
78 | ||
79 | static struct tb_property * | |
80 | tb_property_alloc(const char *key, enum tb_property_type type) | |
81 | { | |
82 | struct tb_property *property; | |
83 | ||
84 | property = kzalloc(sizeof(*property), GFP_KERNEL); | |
85 | if (!property) | |
86 | return NULL; | |
87 | ||
88 | strcpy(property->key, key); | |
89 | property->type = type; | |
90 | INIT_LIST_HEAD(&property->list); | |
91 | ||
92 | return property; | |
93 | } | |
94 | ||
95 | static struct tb_property *tb_property_parse(const u32 *block, size_t block_len, | |
96 | const struct tb_property_entry *entry) | |
97 | { | |
98 | char key[TB_PROPERTY_KEY_SIZE + 1]; | |
99 | struct tb_property *property; | |
100 | struct tb_property_dir *dir; | |
101 | ||
102 | if (!tb_property_entry_valid(entry, block_len)) | |
103 | return NULL; | |
104 | ||
105 | parse_dwdata(key, entry, 2); | |
106 | key[TB_PROPERTY_KEY_SIZE] = '\0'; | |
107 | ||
108 | property = tb_property_alloc(key, entry->type); | |
109 | if (!property) | |
110 | return NULL; | |
111 | ||
112 | property->length = entry->length; | |
113 | ||
114 | switch (property->type) { | |
115 | case TB_PROPERTY_TYPE_DIRECTORY: | |
116 | dir = __tb_property_parse_dir(block, block_len, entry->value, | |
117 | entry->length, false); | |
118 | if (!dir) { | |
119 | kfree(property); | |
120 | return NULL; | |
121 | } | |
122 | property->value.dir = dir; | |
123 | break; | |
124 | ||
125 | case TB_PROPERTY_TYPE_DATA: | |
126 | property->value.data = kcalloc(property->length, sizeof(u32), | |
127 | GFP_KERNEL); | |
128 | if (!property->value.data) { | |
129 | kfree(property); | |
130 | return NULL; | |
131 | } | |
132 | parse_dwdata(property->value.data, block + entry->value, | |
133 | entry->length); | |
134 | break; | |
135 | ||
136 | case TB_PROPERTY_TYPE_TEXT: | |
137 | property->value.text = kcalloc(property->length, sizeof(u32), | |
138 | GFP_KERNEL); | |
139 | if (!property->value.text) { | |
140 | kfree(property); | |
141 | return NULL; | |
142 | } | |
143 | parse_dwdata(property->value.text, block + entry->value, | |
144 | entry->length); | |
145 | /* Force null termination */ | |
146 | property->value.text[property->length * 4 - 1] = '\0'; | |
147 | break; | |
148 | ||
149 | case TB_PROPERTY_TYPE_VALUE: | |
150 | property->value.immediate = entry->value; | |
151 | break; | |
152 | ||
153 | default: | |
154 | property->type = TB_PROPERTY_TYPE_UNKNOWN; | |
155 | break; | |
156 | } | |
157 | ||
158 | return property; | |
159 | } | |
160 | ||
161 | static struct tb_property_dir *__tb_property_parse_dir(const u32 *block, | |
162 | size_t block_len, unsigned int dir_offset, size_t dir_len, bool is_root) | |
163 | { | |
164 | const struct tb_property_entry *entries; | |
165 | size_t i, content_len, nentries; | |
166 | unsigned int content_offset; | |
167 | struct tb_property_dir *dir; | |
168 | ||
169 | dir = kzalloc(sizeof(*dir), GFP_KERNEL); | |
170 | if (!dir) | |
171 | return NULL; | |
172 | ||
173 | if (is_root) { | |
174 | content_offset = dir_offset + 2; | |
175 | content_len = dir_len; | |
176 | } else { | |
177 | dir->uuid = kmemdup(&block[dir_offset], sizeof(*dir->uuid), | |
178 | GFP_KERNEL); | |
179 | content_offset = dir_offset + 4; | |
180 | content_len = dir_len - 4; /* Length includes UUID */ | |
181 | } | |
182 | ||
183 | entries = (const struct tb_property_entry *)&block[content_offset]; | |
184 | nentries = content_len / (sizeof(*entries) / 4); | |
185 | ||
186 | INIT_LIST_HEAD(&dir->properties); | |
187 | ||
188 | for (i = 0; i < nentries; i++) { | |
189 | struct tb_property *property; | |
190 | ||
191 | property = tb_property_parse(block, block_len, &entries[i]); | |
192 | if (!property) { | |
193 | tb_property_free_dir(dir); | |
194 | return NULL; | |
195 | } | |
196 | ||
197 | list_add_tail(&property->list, &dir->properties); | |
198 | } | |
199 | ||
200 | return dir; | |
201 | } | |
202 | ||
203 | /** | |
204 | * tb_property_parse_dir() - Parses properties from given property block | |
205 | * @block: Property block to parse | |
206 | * @block_len: Number of dword elements in the property block | |
207 | * | |
208 | * This function parses the XDomain properties data block into format that | |
209 | * can be traversed using the helper functions provided by this module. | |
210 | * Upon success returns the parsed directory. In case of error returns | |
211 | * %NULL. The resulting &struct tb_property_dir needs to be released by | |
212 | * calling tb_property_free_dir() when not needed anymore. | |
213 | * | |
214 | * The @block is expected to be root directory. | |
215 | */ | |
216 | struct tb_property_dir *tb_property_parse_dir(const u32 *block, | |
217 | size_t block_len) | |
218 | { | |
219 | const struct tb_property_rootdir_entry *rootdir = | |
220 | (const struct tb_property_rootdir_entry *)block; | |
221 | ||
222 | if (rootdir->magic != TB_PROPERTY_ROOTDIR_MAGIC) | |
223 | return NULL; | |
224 | if (rootdir->length > block_len) | |
225 | return NULL; | |
226 | ||
227 | return __tb_property_parse_dir(block, block_len, 0, rootdir->length, | |
228 | true); | |
229 | } | |
230 | ||
231 | /** | |
232 | * tb_property_create_dir() - Creates new property directory | |
233 | * @uuid: UUID used to identify the particular directory | |
234 | * | |
235 | * Creates new, empty property directory. If @uuid is %NULL then the | |
236 | * directory is assumed to be root directory. | |
237 | */ | |
238 | struct tb_property_dir *tb_property_create_dir(const uuid_t *uuid) | |
239 | { | |
240 | struct tb_property_dir *dir; | |
241 | ||
242 | dir = kzalloc(sizeof(*dir), GFP_KERNEL); | |
243 | if (!dir) | |
244 | return NULL; | |
245 | ||
246 | INIT_LIST_HEAD(&dir->properties); | |
247 | if (uuid) { | |
248 | dir->uuid = kmemdup(uuid, sizeof(*dir->uuid), GFP_KERNEL); | |
249 | if (!dir->uuid) { | |
250 | kfree(dir); | |
251 | return NULL; | |
252 | } | |
253 | } | |
254 | ||
255 | return dir; | |
256 | } | |
257 | EXPORT_SYMBOL_GPL(tb_property_create_dir); | |
258 | ||
259 | static void tb_property_free(struct tb_property *property) | |
260 | { | |
261 | switch (property->type) { | |
262 | case TB_PROPERTY_TYPE_DIRECTORY: | |
263 | tb_property_free_dir(property->value.dir); | |
264 | break; | |
265 | ||
266 | case TB_PROPERTY_TYPE_DATA: | |
267 | kfree(property->value.data); | |
268 | break; | |
269 | ||
270 | case TB_PROPERTY_TYPE_TEXT: | |
271 | kfree(property->value.text); | |
272 | break; | |
273 | ||
274 | default: | |
275 | break; | |
276 | } | |
277 | ||
278 | kfree(property); | |
279 | } | |
280 | ||
281 | /** | |
282 | * tb_property_free_dir() - Release memory allocated for property directory | |
283 | * @dir: Directory to release | |
284 | * | |
285 | * This will release all the memory the directory occupies including all | |
286 | * descendants. It is OK to pass %NULL @dir, then the function does | |
287 | * nothing. | |
288 | */ | |
289 | void tb_property_free_dir(struct tb_property_dir *dir) | |
290 | { | |
291 | struct tb_property *property, *tmp; | |
292 | ||
293 | if (!dir) | |
294 | return; | |
295 | ||
296 | list_for_each_entry_safe(property, tmp, &dir->properties, list) { | |
297 | list_del(&property->list); | |
298 | tb_property_free(property); | |
299 | } | |
300 | kfree(dir->uuid); | |
301 | kfree(dir); | |
302 | } | |
303 | EXPORT_SYMBOL_GPL(tb_property_free_dir); | |
304 | ||
305 | static size_t tb_property_dir_length(const struct tb_property_dir *dir, | |
306 | bool recurse, size_t *data_len) | |
307 | { | |
308 | const struct tb_property *property; | |
309 | size_t len = 0; | |
310 | ||
311 | if (dir->uuid) | |
312 | len += sizeof(*dir->uuid) / 4; | |
313 | else | |
314 | len += sizeof(struct tb_property_rootdir_entry) / 4; | |
315 | ||
316 | list_for_each_entry(property, &dir->properties, list) { | |
317 | len += sizeof(struct tb_property_entry) / 4; | |
318 | ||
319 | switch (property->type) { | |
320 | case TB_PROPERTY_TYPE_DIRECTORY: | |
321 | if (recurse) { | |
322 | len += tb_property_dir_length( | |
323 | property->value.dir, recurse, data_len); | |
324 | } | |
325 | /* Reserve dword padding after each directory */ | |
326 | if (data_len) | |
327 | *data_len += 1; | |
328 | break; | |
329 | ||
330 | case TB_PROPERTY_TYPE_DATA: | |
331 | case TB_PROPERTY_TYPE_TEXT: | |
332 | if (data_len) | |
333 | *data_len += property->length; | |
334 | break; | |
335 | ||
336 | default: | |
337 | break; | |
338 | } | |
339 | } | |
340 | ||
341 | return len; | |
342 | } | |
343 | ||
344 | static ssize_t __tb_property_format_dir(const struct tb_property_dir *dir, | |
345 | u32 *block, unsigned int start_offset, size_t block_len) | |
346 | { | |
347 | unsigned int data_offset, dir_end; | |
348 | const struct tb_property *property; | |
349 | struct tb_property_entry *entry; | |
350 | size_t dir_len, data_len = 0; | |
351 | int ret; | |
352 | ||
353 | /* | |
354 | * The structure of property block looks like following. Leaf | |
355 | * data/text is included right after the directory and each | |
356 | * directory follows each other (even nested ones). | |
357 | * | |
358 | * +----------+ <-- start_offset | |
359 | * | header | <-- root directory header | |
360 | * +----------+ --- | |
361 | * | entry 0 | -^--------------------. | |
362 | * +----------+ | | | |
363 | * | entry 1 | -|--------------------|--. | |
364 | * +----------+ | | | | |
365 | * | entry 2 | -|-----------------. | | | |
366 | * +----------+ | | | | | |
367 | * : : | dir_len | | | | |
368 | * . . | | | | | |
369 | * : : | | | | | |
370 | * +----------+ | | | | | |
371 | * | entry n | v | | | | |
372 | * +----------+ <-- data_offset | | | | |
373 | * | data 0 | <------------------|--' | | |
374 | * +----------+ | | | |
375 | * | data 1 | <------------------|-----' | |
376 | * +----------+ | | |
377 | * | 00000000 | padding | | |
378 | * +----------+ <-- dir_end <------' | |
379 | * | UUID | <-- directory UUID (child directory) | |
380 | * +----------+ | |
381 | * | entry 0 | | |
382 | * +----------+ | |
383 | * | entry 1 | | |
384 | * +----------+ | |
385 | * : : | |
386 | * . . | |
387 | * : : | |
388 | * +----------+ | |
389 | * | entry n | | |
390 | * +----------+ | |
391 | * | data 0 | | |
392 | * +----------+ | |
393 | * | |
394 | * We use dir_end to hold pointer to the end of the directory. It | |
395 | * will increase as we add directories and each directory should be | |
396 | * added starting from previous dir_end. | |
397 | */ | |
398 | dir_len = tb_property_dir_length(dir, false, &data_len); | |
399 | data_offset = start_offset + dir_len; | |
400 | dir_end = start_offset + data_len + dir_len; | |
401 | ||
402 | if (data_offset > dir_end) | |
403 | return -EINVAL; | |
404 | if (dir_end > block_len) | |
405 | return -EINVAL; | |
406 | ||
407 | /* Write headers first */ | |
408 | if (dir->uuid) { | |
409 | struct tb_property_dir_entry *pe; | |
410 | ||
411 | pe = (struct tb_property_dir_entry *)&block[start_offset]; | |
412 | memcpy(pe->uuid, dir->uuid, sizeof(pe->uuid)); | |
413 | entry = pe->entries; | |
414 | } else { | |
415 | struct tb_property_rootdir_entry *re; | |
416 | ||
417 | re = (struct tb_property_rootdir_entry *)&block[start_offset]; | |
418 | re->magic = TB_PROPERTY_ROOTDIR_MAGIC; | |
419 | re->length = dir_len - sizeof(*re) / 4; | |
420 | entry = re->entries; | |
421 | } | |
422 | ||
423 | list_for_each_entry(property, &dir->properties, list) { | |
424 | const struct tb_property_dir *child; | |
425 | ||
426 | format_dwdata(entry, property->key, 2); | |
427 | entry->type = property->type; | |
428 | ||
429 | switch (property->type) { | |
430 | case TB_PROPERTY_TYPE_DIRECTORY: | |
431 | child = property->value.dir; | |
432 | ret = __tb_property_format_dir(child, block, dir_end, | |
433 | block_len); | |
434 | if (ret < 0) | |
435 | return ret; | |
436 | entry->length = tb_property_dir_length(child, false, | |
437 | NULL); | |
438 | entry->value = dir_end; | |
439 | dir_end = ret; | |
440 | break; | |
441 | ||
442 | case TB_PROPERTY_TYPE_DATA: | |
443 | format_dwdata(&block[data_offset], property->value.data, | |
444 | property->length); | |
445 | entry->length = property->length; | |
446 | entry->value = data_offset; | |
447 | data_offset += entry->length; | |
448 | break; | |
449 | ||
450 | case TB_PROPERTY_TYPE_TEXT: | |
451 | format_dwdata(&block[data_offset], property->value.text, | |
452 | property->length); | |
453 | entry->length = property->length; | |
454 | entry->value = data_offset; | |
455 | data_offset += entry->length; | |
456 | break; | |
457 | ||
458 | case TB_PROPERTY_TYPE_VALUE: | |
459 | entry->length = property->length; | |
460 | entry->value = property->value.immediate; | |
461 | break; | |
462 | ||
463 | default: | |
464 | break; | |
465 | } | |
466 | ||
467 | entry++; | |
468 | } | |
469 | ||
470 | return dir_end; | |
471 | } | |
472 | ||
473 | /** | |
474 | * tb_property_format_dir() - Formats directory to the packed XDomain format | |
475 | * @dir: Directory to format | |
476 | * @block: Property block where the packed data is placed | |
477 | * @block_len: Length of the property block | |
478 | * | |
479 | * This function formats the directory to the packed format that can be | |
480 | * then send over the thunderbolt fabric to receiving host. Returns %0 in | |
481 | * case of success and negative errno on faulure. Passing %NULL in @block | |
482 | * returns number of entries the block takes. | |
483 | */ | |
484 | ssize_t tb_property_format_dir(const struct tb_property_dir *dir, u32 *block, | |
485 | size_t block_len) | |
486 | { | |
487 | ssize_t ret; | |
488 | ||
489 | if (!block) { | |
490 | size_t dir_len, data_len = 0; | |
491 | ||
492 | dir_len = tb_property_dir_length(dir, true, &data_len); | |
493 | return dir_len + data_len; | |
494 | } | |
495 | ||
496 | ret = __tb_property_format_dir(dir, block, 0, block_len); | |
497 | return ret < 0 ? ret : 0; | |
498 | } | |
499 | ||
500 | /** | |
501 | * tb_property_add_immediate() - Add immediate property to directory | |
502 | * @parent: Directory to add the property | |
503 | * @key: Key for the property | |
504 | * @value: Immediate value to store with the property | |
505 | */ | |
506 | int tb_property_add_immediate(struct tb_property_dir *parent, const char *key, | |
507 | u32 value) | |
508 | { | |
509 | struct tb_property *property; | |
510 | ||
511 | if (!tb_property_key_valid(key)) | |
512 | return -EINVAL; | |
513 | ||
514 | property = tb_property_alloc(key, TB_PROPERTY_TYPE_VALUE); | |
515 | if (!property) | |
516 | return -ENOMEM; | |
517 | ||
518 | property->length = 1; | |
519 | property->value.immediate = value; | |
520 | ||
521 | list_add_tail(&property->list, &parent->properties); | |
522 | return 0; | |
523 | } | |
524 | EXPORT_SYMBOL_GPL(tb_property_add_immediate); | |
525 | ||
526 | /** | |
527 | * tb_property_add_data() - Adds arbitrary data property to directory | |
528 | * @parent: Directory to add the property | |
529 | * @key: Key for the property | |
530 | * @buf: Data buffer to add | |
531 | * @buflen: Number of bytes in the data buffer | |
532 | * | |
533 | * Function takes a copy of @buf and adds it to the directory. | |
534 | */ | |
535 | int tb_property_add_data(struct tb_property_dir *parent, const char *key, | |
536 | const void *buf, size_t buflen) | |
537 | { | |
538 | /* Need to pad to dword boundary */ | |
539 | size_t size = round_up(buflen, 4); | |
540 | struct tb_property *property; | |
541 | ||
542 | if (!tb_property_key_valid(key)) | |
543 | return -EINVAL; | |
544 | ||
545 | property = tb_property_alloc(key, TB_PROPERTY_TYPE_DATA); | |
546 | if (!property) | |
547 | return -ENOMEM; | |
548 | ||
549 | property->length = size / 4; | |
550 | property->value.data = kzalloc(size, GFP_KERNEL); | |
551 | memcpy(property->value.data, buf, buflen); | |
552 | ||
553 | list_add_tail(&property->list, &parent->properties); | |
554 | return 0; | |
555 | } | |
556 | EXPORT_SYMBOL_GPL(tb_property_add_data); | |
557 | ||
558 | /** | |
559 | * tb_property_add_text() - Adds string property to directory | |
560 | * @parent: Directory to add the property | |
561 | * @key: Key for the property | |
562 | * @text: String to add | |
563 | * | |
564 | * Function takes a copy of @text and adds it to the directory. | |
565 | */ | |
566 | int tb_property_add_text(struct tb_property_dir *parent, const char *key, | |
567 | const char *text) | |
568 | { | |
569 | /* Need to pad to dword boundary */ | |
570 | size_t size = round_up(strlen(text) + 1, 4); | |
571 | struct tb_property *property; | |
572 | ||
573 | if (!tb_property_key_valid(key)) | |
574 | return -EINVAL; | |
575 | ||
576 | property = tb_property_alloc(key, TB_PROPERTY_TYPE_TEXT); | |
577 | if (!property) | |
578 | return -ENOMEM; | |
579 | ||
580 | property->length = size / 4; | |
581 | property->value.data = kzalloc(size, GFP_KERNEL); | |
582 | strcpy(property->value.text, text); | |
583 | ||
584 | list_add_tail(&property->list, &parent->properties); | |
585 | return 0; | |
586 | } | |
587 | EXPORT_SYMBOL_GPL(tb_property_add_text); | |
588 | ||
589 | /** | |
590 | * tb_property_add_dir() - Adds a directory to the parent directory | |
591 | * @parent: Directory to add the property | |
592 | * @key: Key for the property | |
593 | * @dir: Directory to add | |
594 | */ | |
595 | int tb_property_add_dir(struct tb_property_dir *parent, const char *key, | |
596 | struct tb_property_dir *dir) | |
597 | { | |
598 | struct tb_property *property; | |
599 | ||
600 | if (!tb_property_key_valid(key)) | |
601 | return -EINVAL; | |
602 | ||
603 | property = tb_property_alloc(key, TB_PROPERTY_TYPE_DIRECTORY); | |
604 | if (!property) | |
605 | return -ENOMEM; | |
606 | ||
607 | property->value.dir = dir; | |
608 | ||
609 | list_add_tail(&property->list, &parent->properties); | |
610 | return 0; | |
611 | } | |
612 | EXPORT_SYMBOL_GPL(tb_property_add_dir); | |
613 | ||
614 | /** | |
615 | * tb_property_remove() - Removes property from a parent directory | |
616 | * @property: Property to remove | |
617 | * | |
618 | * Note memory for @property is released as well so it is not allowed to | |
619 | * touch the object after call to this function. | |
620 | */ | |
621 | void tb_property_remove(struct tb_property *property) | |
622 | { | |
623 | list_del(&property->list); | |
624 | kfree(property); | |
625 | } | |
626 | EXPORT_SYMBOL_GPL(tb_property_remove); | |
627 | ||
628 | /** | |
629 | * tb_property_find() - Find a property from a directory | |
630 | * @dir: Directory where the property is searched | |
631 | * @key: Key to look for | |
632 | * @type: Type of the property | |
633 | * | |
634 | * Finds and returns property from the given directory. Does not recurse | |
635 | * into sub-directories. Returns %NULL if the property was not found. | |
636 | */ | |
637 | struct tb_property *tb_property_find(struct tb_property_dir *dir, | |
638 | const char *key, enum tb_property_type type) | |
639 | { | |
640 | struct tb_property *property; | |
641 | ||
642 | list_for_each_entry(property, &dir->properties, list) { | |
643 | if (property->type == type && !strcmp(property->key, key)) | |
644 | return property; | |
645 | } | |
646 | ||
647 | return NULL; | |
648 | } | |
649 | EXPORT_SYMBOL_GPL(tb_property_find); | |
650 | ||
651 | /** | |
652 | * tb_property_get_next() - Get next property from directory | |
653 | * @dir: Directory holding properties | |
654 | * @prev: Previous property in the directory (%NULL returns the first) | |
655 | */ | |
656 | struct tb_property *tb_property_get_next(struct tb_property_dir *dir, | |
657 | struct tb_property *prev) | |
658 | { | |
659 | if (prev) { | |
660 | if (list_is_last(&prev->list, &dir->properties)) | |
661 | return NULL; | |
662 | return list_next_entry(prev, list); | |
663 | } | |
664 | return list_first_entry_or_null(&dir->properties, struct tb_property, | |
665 | list); | |
666 | } | |
667 | EXPORT_SYMBOL_GPL(tb_property_get_next); |