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