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7518b589 PA |
1 | /* |
2 | * Functions for working with device tree overlays | |
3 | * | |
4 | * Copyright (C) 2012 Pantelis Antoniou <panto@antoniou-consulting.com> | |
5 | * Copyright (C) 2012 Texas Instruments Inc. | |
6 | * | |
7 | * This program is free software; you can redistribute it and/or | |
8 | * modify it under the terms of the GNU General Public License | |
9 | * version 2 as published by the Free Software Foundation. | |
10 | */ | |
606ad42a RH |
11 | |
12 | #define pr_fmt(fmt) "OF: overlay: " fmt | |
13 | ||
7518b589 PA |
14 | #include <linux/kernel.h> |
15 | #include <linux/module.h> | |
16 | #include <linux/of.h> | |
17 | #include <linux/of_device.h> | |
18 | #include <linux/string.h> | |
19 | #include <linux/ctype.h> | |
20 | #include <linux/errno.h> | |
21 | #include <linux/string.h> | |
22 | #include <linux/slab.h> | |
23 | #include <linux/err.h> | |
0d1886df | 24 | #include <linux/idr.h> |
7518b589 PA |
25 | |
26 | #include "of_private.h" | |
27 | ||
28 | /** | |
29 | * struct of_overlay_info - Holds a single overlay info | |
30 | * @target: target of the overlay operation | |
31 | * @overlay: pointer to the overlay contents node | |
32 | * | |
33 | * Holds a single overlay state, including all the overlay logs & | |
34 | * records. | |
35 | */ | |
36 | struct of_overlay_info { | |
37 | struct device_node *target; | |
38 | struct device_node *overlay; | |
39 | }; | |
40 | ||
41 | /** | |
42 | * struct of_overlay - Holds a complete overlay transaction | |
43 | * @node: List on which we are located | |
44 | * @count: Count of ovinfo structures | |
45 | * @ovinfo_tab: Overlay info table (count sized) | |
46 | * @cset: Changeset to be used | |
47 | * | |
48 | * Holds a complete overlay transaction | |
49 | */ | |
50 | struct of_overlay { | |
51 | int id; | |
52 | struct list_head node; | |
53 | int count; | |
54 | struct of_overlay_info *ovinfo_tab; | |
55 | struct of_changeset cset; | |
56 | }; | |
57 | ||
58 | static int of_overlay_apply_one(struct of_overlay *ov, | |
59 | struct device_node *target, const struct device_node *overlay); | |
60 | ||
39a842e2 AT |
61 | static BLOCKING_NOTIFIER_HEAD(of_overlay_chain); |
62 | ||
63 | int of_overlay_notifier_register(struct notifier_block *nb) | |
64 | { | |
65 | return blocking_notifier_chain_register(&of_overlay_chain, nb); | |
66 | } | |
67 | EXPORT_SYMBOL_GPL(of_overlay_notifier_register); | |
68 | ||
69 | int of_overlay_notifier_unregister(struct notifier_block *nb) | |
70 | { | |
71 | return blocking_notifier_chain_unregister(&of_overlay_chain, nb); | |
72 | } | |
73 | EXPORT_SYMBOL_GPL(of_overlay_notifier_unregister); | |
74 | ||
75 | static int of_overlay_notify(struct of_overlay *ov, | |
76 | enum of_overlay_notify_action action) | |
77 | { | |
78 | struct of_overlay_notify_data nd; | |
79 | int i, ret; | |
80 | ||
81 | for (i = 0; i < ov->count; i++) { | |
82 | struct of_overlay_info *ovinfo = &ov->ovinfo_tab[i]; | |
83 | ||
84 | nd.target = ovinfo->target; | |
85 | nd.overlay = ovinfo->overlay; | |
86 | ||
87 | ret = blocking_notifier_call_chain(&of_overlay_chain, | |
88 | action, &nd); | |
89 | if (ret) | |
90 | return notifier_to_errno(ret); | |
91 | } | |
92 | ||
93 | return 0; | |
94 | } | |
95 | ||
7518b589 PA |
96 | static int of_overlay_apply_single_property(struct of_overlay *ov, |
97 | struct device_node *target, struct property *prop) | |
98 | { | |
99 | struct property *propn, *tprop; | |
100 | ||
101 | /* NOTE: Multiple changes of single properties not supported */ | |
102 | tprop = of_find_property(target, prop->name, NULL); | |
103 | ||
104 | /* special properties are not meant to be updated (silent NOP) */ | |
105 | if (of_prop_cmp(prop->name, "name") == 0 || | |
106 | of_prop_cmp(prop->name, "phandle") == 0 || | |
107 | of_prop_cmp(prop->name, "linux,phandle") == 0) | |
108 | return 0; | |
109 | ||
110 | propn = __of_prop_dup(prop, GFP_KERNEL); | |
111 | if (propn == NULL) | |
112 | return -ENOMEM; | |
113 | ||
114 | /* not found? add */ | |
115 | if (tprop == NULL) | |
116 | return of_changeset_add_property(&ov->cset, target, propn); | |
117 | ||
118 | /* found? update */ | |
119 | return of_changeset_update_property(&ov->cset, target, propn); | |
120 | } | |
121 | ||
122 | static int of_overlay_apply_single_device_node(struct of_overlay *ov, | |
123 | struct device_node *target, struct device_node *child) | |
124 | { | |
125 | const char *cname; | |
d3a89165 | 126 | struct device_node *tchild; |
7518b589 PA |
127 | int ret = 0; |
128 | ||
129 | cname = kbasename(child->full_name); | |
130 | if (cname == NULL) | |
131 | return -ENOMEM; | |
132 | ||
133 | /* NOTE: Multiple mods of created nodes not supported */ | |
134 | tchild = of_get_child_by_name(target, cname); | |
135 | if (tchild != NULL) { | |
136 | /* apply overlay recursively */ | |
137 | ret = of_overlay_apply_one(ov, tchild, child); | |
138 | of_node_put(tchild); | |
139 | } else { | |
140 | /* create empty tree as a target */ | |
141 | tchild = __of_node_dup(child, "%s/%s", target->full_name, cname); | |
142 | if (!tchild) | |
143 | return -ENOMEM; | |
144 | ||
145 | /* point to parent */ | |
146 | tchild->parent = target; | |
147 | ||
148 | ret = of_changeset_attach_node(&ov->cset, tchild); | |
149 | if (ret) | |
150 | return ret; | |
151 | ||
152 | ret = of_overlay_apply_one(ov, tchild, child); | |
153 | if (ret) | |
154 | return ret; | |
7518b589 PA |
155 | } |
156 | ||
157 | return ret; | |
158 | } | |
159 | ||
160 | /* | |
161 | * Apply a single overlay node recursively. | |
162 | * | |
163 | * Note that the in case of an error the target node is left | |
164 | * in a inconsistent state. Error recovery should be performed | |
165 | * by using the changeset. | |
166 | */ | |
167 | static int of_overlay_apply_one(struct of_overlay *ov, | |
168 | struct device_node *target, const struct device_node *overlay) | |
169 | { | |
170 | struct device_node *child; | |
171 | struct property *prop; | |
172 | int ret; | |
173 | ||
174 | for_each_property_of_node(overlay, prop) { | |
175 | ret = of_overlay_apply_single_property(ov, target, prop); | |
176 | if (ret) { | |
606ad42a RH |
177 | pr_err("Failed to apply prop @%s/%s\n", |
178 | target->full_name, prop->name); | |
7518b589 PA |
179 | return ret; |
180 | } | |
181 | } | |
182 | ||
183 | for_each_child_of_node(overlay, child) { | |
184 | ret = of_overlay_apply_single_device_node(ov, target, child); | |
185 | if (ret != 0) { | |
606ad42a RH |
186 | pr_err("Failed to apply single node @%s/%s\n", |
187 | target->full_name, child->name); | |
001cf504 | 188 | of_node_put(child); |
7518b589 PA |
189 | return ret; |
190 | } | |
191 | } | |
192 | ||
193 | return 0; | |
194 | } | |
195 | ||
196 | /** | |
197 | * of_overlay_apply() - Apply @count overlays pointed at by @ovinfo_tab | |
198 | * @ov: Overlay to apply | |
199 | * | |
200 | * Applies the overlays given, while handling all error conditions | |
201 | * appropriately. Either the operation succeeds, or if it fails the | |
202 | * live tree is reverted to the state before the attempt. | |
203 | * Returns 0, or an error if the overlay attempt failed. | |
204 | */ | |
205 | static int of_overlay_apply(struct of_overlay *ov) | |
206 | { | |
207 | int i, err; | |
208 | ||
209 | /* first we apply the overlays atomically */ | |
210 | for (i = 0; i < ov->count; i++) { | |
211 | struct of_overlay_info *ovinfo = &ov->ovinfo_tab[i]; | |
212 | ||
213 | err = of_overlay_apply_one(ov, ovinfo->target, ovinfo->overlay); | |
214 | if (err != 0) { | |
606ad42a | 215 | pr_err("apply failed '%s'\n", ovinfo->target->full_name); |
7518b589 PA |
216 | return err; |
217 | } | |
218 | } | |
219 | ||
220 | return 0; | |
221 | } | |
222 | ||
223 | /* | |
224 | * Find the target node using a number of different strategies | |
225 | * in order of preference | |
226 | * | |
227 | * "target" property containing the phandle of the target | |
228 | * "target-path" property containing the path of the target | |
229 | */ | |
230 | static struct device_node *find_target_node(struct device_node *info_node) | |
231 | { | |
232 | const char *path; | |
233 | u32 val; | |
234 | int ret; | |
235 | ||
236 | /* first try to go by using the target as a phandle */ | |
237 | ret = of_property_read_u32(info_node, "target", &val); | |
238 | if (ret == 0) | |
239 | return of_find_node_by_phandle(val); | |
240 | ||
241 | /* now try to locate by path */ | |
242 | ret = of_property_read_string(info_node, "target-path", &path); | |
243 | if (ret == 0) | |
244 | return of_find_node_by_path(path); | |
245 | ||
606ad42a | 246 | pr_err("Failed to find target for node %p (%s)\n", |
7518b589 PA |
247 | info_node, info_node->name); |
248 | ||
249 | return NULL; | |
250 | } | |
251 | ||
252 | /** | |
253 | * of_fill_overlay_info() - Fill an overlay info structure | |
254 | * @ov Overlay to fill | |
255 | * @info_node: Device node containing the overlay | |
256 | * @ovinfo: Pointer to the overlay info structure to fill | |
257 | * | |
258 | * Fills an overlay info structure with the overlay information | |
259 | * from a device node. This device node must have a target property | |
260 | * which contains a phandle of the overlay target node, and an | |
261 | * __overlay__ child node which has the overlay contents. | |
262 | * Both ovinfo->target & ovinfo->overlay have their references taken. | |
263 | * | |
264 | * Returns 0 on success, or a negative error value. | |
265 | */ | |
266 | static int of_fill_overlay_info(struct of_overlay *ov, | |
267 | struct device_node *info_node, struct of_overlay_info *ovinfo) | |
268 | { | |
269 | ovinfo->overlay = of_get_child_by_name(info_node, "__overlay__"); | |
270 | if (ovinfo->overlay == NULL) | |
271 | goto err_fail; | |
272 | ||
273 | ovinfo->target = find_target_node(info_node); | |
274 | if (ovinfo->target == NULL) | |
275 | goto err_fail; | |
276 | ||
277 | return 0; | |
278 | ||
279 | err_fail: | |
280 | of_node_put(ovinfo->target); | |
281 | of_node_put(ovinfo->overlay); | |
282 | ||
283 | memset(ovinfo, 0, sizeof(*ovinfo)); | |
284 | return -EINVAL; | |
285 | } | |
286 | ||
287 | /** | |
288 | * of_build_overlay_info() - Build an overlay info array | |
289 | * @ov Overlay to build | |
290 | * @tree: Device node containing all the overlays | |
291 | * | |
292 | * Helper function that given a tree containing overlay information, | |
293 | * allocates and builds an overlay info array containing it, ready | |
294 | * for use using of_overlay_apply. | |
295 | * | |
296 | * Returns 0 on success with the @cntp @ovinfop pointers valid, | |
297 | * while on error a negative error value is returned. | |
298 | */ | |
299 | static int of_build_overlay_info(struct of_overlay *ov, | |
300 | struct device_node *tree) | |
301 | { | |
302 | struct device_node *node; | |
303 | struct of_overlay_info *ovinfo; | |
304 | int cnt, err; | |
305 | ||
306 | /* worst case; every child is a node */ | |
307 | cnt = 0; | |
308 | for_each_child_of_node(tree, node) | |
309 | cnt++; | |
310 | ||
311 | ovinfo = kcalloc(cnt, sizeof(*ovinfo), GFP_KERNEL); | |
312 | if (ovinfo == NULL) | |
313 | return -ENOMEM; | |
314 | ||
315 | cnt = 0; | |
316 | for_each_child_of_node(tree, node) { | |
317 | memset(&ovinfo[cnt], 0, sizeof(*ovinfo)); | |
318 | err = of_fill_overlay_info(ov, node, &ovinfo[cnt]); | |
319 | if (err == 0) | |
320 | cnt++; | |
321 | } | |
322 | ||
323 | /* if nothing filled, return error */ | |
324 | if (cnt == 0) { | |
325 | kfree(ovinfo); | |
326 | return -ENODEV; | |
327 | } | |
328 | ||
329 | ov->count = cnt; | |
330 | ov->ovinfo_tab = ovinfo; | |
331 | ||
332 | return 0; | |
333 | } | |
334 | ||
335 | /** | |
336 | * of_free_overlay_info() - Free an overlay info array | |
337 | * @ov Overlay to free the overlay info from | |
338 | * @ovinfo_tab: Array of overlay_info's to free | |
339 | * | |
340 | * Releases the memory of a previously allocated ovinfo array | |
341 | * by of_build_overlay_info. | |
342 | * Returns 0, or an error if the arguments are bogus. | |
343 | */ | |
344 | static int of_free_overlay_info(struct of_overlay *ov) | |
345 | { | |
346 | struct of_overlay_info *ovinfo; | |
347 | int i; | |
348 | ||
349 | /* do it in reverse */ | |
350 | for (i = ov->count - 1; i >= 0; i--) { | |
351 | ovinfo = &ov->ovinfo_tab[i]; | |
352 | ||
353 | of_node_put(ovinfo->target); | |
354 | of_node_put(ovinfo->overlay); | |
355 | } | |
356 | kfree(ov->ovinfo_tab); | |
357 | ||
358 | return 0; | |
359 | } | |
360 | ||
361 | static LIST_HEAD(ov_list); | |
362 | static DEFINE_IDR(ov_idr); | |
363 | ||
364 | /** | |
365 | * of_overlay_create() - Create and apply an overlay | |
366 | * @tree: Device node containing all the overlays | |
367 | * | |
368 | * Creates and applies an overlay while also keeping track | |
369 | * of the overlay in a list. This list can be used to prevent | |
370 | * illegal overlay removals. | |
371 | * | |
94a8bf97 | 372 | * Returns the id of the created overlay, or a negative error number |
7518b589 PA |
373 | */ |
374 | int of_overlay_create(struct device_node *tree) | |
375 | { | |
376 | struct of_overlay *ov; | |
377 | int err, id; | |
378 | ||
379 | /* allocate the overlay structure */ | |
380 | ov = kzalloc(sizeof(*ov), GFP_KERNEL); | |
381 | if (ov == NULL) | |
382 | return -ENOMEM; | |
383 | ov->id = -1; | |
384 | ||
385 | INIT_LIST_HEAD(&ov->node); | |
386 | ||
387 | of_changeset_init(&ov->cset); | |
388 | ||
389 | mutex_lock(&of_mutex); | |
390 | ||
391 | id = idr_alloc(&ov_idr, ov, 0, 0, GFP_KERNEL); | |
392 | if (id < 0) { | |
7518b589 PA |
393 | err = id; |
394 | goto err_destroy_trans; | |
395 | } | |
396 | ov->id = id; | |
397 | ||
398 | /* build the overlay info structures */ | |
399 | err = of_build_overlay_info(ov, tree); | |
400 | if (err) { | |
606ad42a RH |
401 | pr_err("of_build_overlay_info() failed for tree@%s\n", |
402 | tree->full_name); | |
7518b589 PA |
403 | goto err_free_idr; |
404 | } | |
405 | ||
39a842e2 AT |
406 | err = of_overlay_notify(ov, OF_OVERLAY_PRE_APPLY); |
407 | if (err < 0) { | |
408 | pr_err("%s: Pre-apply notifier failed (err=%d)\n", | |
409 | __func__, err); | |
410 | goto err_free_idr; | |
411 | } | |
412 | ||
7518b589 PA |
413 | /* apply the overlay */ |
414 | err = of_overlay_apply(ov); | |
606ad42a | 415 | if (err) |
7518b589 | 416 | goto err_abort_trans; |
7518b589 PA |
417 | |
418 | /* apply the changeset */ | |
18322377 | 419 | err = __of_changeset_apply(&ov->cset); |
606ad42a | 420 | if (err) |
7518b589 | 421 | goto err_revert_overlay; |
606ad42a | 422 | |
7518b589 PA |
423 | |
424 | /* add to the tail of the overlay list */ | |
425 | list_add_tail(&ov->node, &ov_list); | |
426 | ||
39a842e2 AT |
427 | of_overlay_notify(ov, OF_OVERLAY_POST_APPLY); |
428 | ||
7518b589 PA |
429 | mutex_unlock(&of_mutex); |
430 | ||
431 | return id; | |
432 | ||
433 | err_revert_overlay: | |
434 | err_abort_trans: | |
435 | of_free_overlay_info(ov); | |
436 | err_free_idr: | |
437 | idr_remove(&ov_idr, ov->id); | |
438 | err_destroy_trans: | |
439 | of_changeset_destroy(&ov->cset); | |
440 | kfree(ov); | |
441 | mutex_unlock(&of_mutex); | |
442 | ||
443 | return err; | |
444 | } | |
445 | EXPORT_SYMBOL_GPL(of_overlay_create); | |
446 | ||
447 | /* check whether the given node, lies under the given tree */ | |
448 | static int overlay_subtree_check(struct device_node *tree, | |
449 | struct device_node *dn) | |
450 | { | |
451 | struct device_node *child; | |
452 | ||
453 | /* match? */ | |
454 | if (tree == dn) | |
455 | return 1; | |
456 | ||
457 | for_each_child_of_node(tree, child) { | |
001cf504 JL |
458 | if (overlay_subtree_check(child, dn)) { |
459 | of_node_put(child); | |
7518b589 | 460 | return 1; |
001cf504 | 461 | } |
7518b589 PA |
462 | } |
463 | ||
464 | return 0; | |
465 | } | |
466 | ||
467 | /* check whether this overlay is the topmost */ | |
468 | static int overlay_is_topmost(struct of_overlay *ov, struct device_node *dn) | |
469 | { | |
470 | struct of_overlay *ovt; | |
471 | struct of_changeset_entry *ce; | |
472 | ||
473 | list_for_each_entry_reverse(ovt, &ov_list, node) { | |
474 | /* if we hit ourselves, we're done */ | |
475 | if (ovt == ov) | |
476 | break; | |
477 | ||
478 | /* check against each subtree affected by this overlay */ | |
479 | list_for_each_entry(ce, &ovt->cset.entries, node) { | |
480 | if (overlay_subtree_check(ce->np, dn)) { | |
481 | pr_err("%s: #%d clashes #%d @%s\n", | |
482 | __func__, ov->id, ovt->id, | |
483 | dn->full_name); | |
484 | return 0; | |
485 | } | |
486 | } | |
487 | } | |
488 | ||
489 | /* overlay is topmost */ | |
490 | return 1; | |
491 | } | |
492 | ||
493 | /* | |
494 | * We can safely remove the overlay only if it's the top-most one. | |
495 | * Newly applied overlays are inserted at the tail of the overlay list, | |
496 | * so a top most overlay is the one that is closest to the tail. | |
497 | * | |
498 | * The topmost check is done by exploiting this property. For each | |
499 | * affected device node in the log list we check if this overlay is | |
500 | * the one closest to the tail. If another overlay has affected this | |
501 | * device node and is closest to the tail, then removal is not permited. | |
502 | */ | |
503 | static int overlay_removal_is_ok(struct of_overlay *ov) | |
504 | { | |
505 | struct of_changeset_entry *ce; | |
506 | ||
507 | list_for_each_entry(ce, &ov->cset.entries, node) { | |
508 | if (!overlay_is_topmost(ov, ce->np)) { | |
606ad42a | 509 | pr_err("overlay #%d is not topmost\n", ov->id); |
7518b589 PA |
510 | return 0; |
511 | } | |
512 | } | |
513 | ||
514 | return 1; | |
515 | } | |
516 | ||
517 | /** | |
518 | * of_overlay_destroy() - Removes an overlay | |
519 | * @id: Overlay id number returned by a previous call to of_overlay_create | |
520 | * | |
521 | * Removes an overlay if it is permissible. | |
522 | * | |
94a8bf97 | 523 | * Returns 0 on success, or a negative error number |
7518b589 PA |
524 | */ |
525 | int of_overlay_destroy(int id) | |
526 | { | |
527 | struct of_overlay *ov; | |
528 | int err; | |
529 | ||
530 | mutex_lock(&of_mutex); | |
531 | ||
532 | ov = idr_find(&ov_idr, id); | |
533 | if (ov == NULL) { | |
534 | err = -ENODEV; | |
606ad42a | 535 | pr_err("destroy: Could not find overlay #%d\n", id); |
7518b589 PA |
536 | goto out; |
537 | } | |
538 | ||
539 | /* check whether the overlay is safe to remove */ | |
540 | if (!overlay_removal_is_ok(ov)) { | |
541 | err = -EBUSY; | |
7518b589 PA |
542 | goto out; |
543 | } | |
544 | ||
39a842e2 | 545 | of_overlay_notify(ov, OF_OVERLAY_PRE_REMOVE); |
7518b589 | 546 | list_del(&ov->node); |
18322377 | 547 | __of_changeset_revert(&ov->cset); |
39a842e2 | 548 | of_overlay_notify(ov, OF_OVERLAY_POST_REMOVE); |
7518b589 PA |
549 | of_free_overlay_info(ov); |
550 | idr_remove(&ov_idr, id); | |
551 | of_changeset_destroy(&ov->cset); | |
552 | kfree(ov); | |
553 | ||
554 | err = 0; | |
555 | ||
556 | out: | |
557 | mutex_unlock(&of_mutex); | |
558 | ||
559 | return err; | |
560 | } | |
561 | EXPORT_SYMBOL_GPL(of_overlay_destroy); | |
562 | ||
563 | /** | |
564 | * of_overlay_destroy_all() - Removes all overlays from the system | |
565 | * | |
566 | * Removes all overlays from the system in the correct order. | |
567 | * | |
94a8bf97 | 568 | * Returns 0 on success, or a negative error number |
7518b589 PA |
569 | */ |
570 | int of_overlay_destroy_all(void) | |
571 | { | |
572 | struct of_overlay *ov, *ovn; | |
573 | ||
574 | mutex_lock(&of_mutex); | |
575 | ||
576 | /* the tail of list is guaranteed to be safe to remove */ | |
577 | list_for_each_entry_safe_reverse(ov, ovn, &ov_list, node) { | |
578 | list_del(&ov->node); | |
18322377 | 579 | __of_changeset_revert(&ov->cset); |
7518b589 PA |
580 | of_free_overlay_info(ov); |
581 | idr_remove(&ov_idr, ov->id); | |
582 | kfree(ov); | |
583 | } | |
584 | ||
585 | mutex_unlock(&of_mutex); | |
586 | ||
587 | return 0; | |
588 | } | |
589 | EXPORT_SYMBOL_GPL(of_overlay_destroy_all); |