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