xref: /openbmc/linux/drivers/of/platform.c (revision 7ae5c03a)
1 // SPDX-License-Identifier: GPL-2.0+
2 /*
3  *    Copyright (C) 2006 Benjamin Herrenschmidt, IBM Corp.
4  *			 <benh@kernel.crashing.org>
5  *    and		 Arnd Bergmann, IBM Corp.
6  *    Merged from powerpc/kernel/of_platform.c and
7  *    sparc{,64}/kernel/of_device.c by Stephen Rothwell
8  */
9 
10 #define pr_fmt(fmt)	"OF: " fmt
11 
12 #include <linux/errno.h>
13 #include <linux/module.h>
14 #include <linux/amba/bus.h>
15 #include <linux/device.h>
16 #include <linux/dma-mapping.h>
17 #include <linux/slab.h>
18 #include <linux/of_address.h>
19 #include <linux/of_device.h>
20 #include <linux/of_irq.h>
21 #include <linux/of_platform.h>
22 #include <linux/platform_device.h>
23 
24 const struct of_device_id of_default_bus_match_table[] = {
25 	{ .compatible = "simple-bus", },
26 	{ .compatible = "simple-mfd", },
27 	{ .compatible = "isa", },
28 #ifdef CONFIG_ARM_AMBA
29 	{ .compatible = "arm,amba-bus", },
30 #endif /* CONFIG_ARM_AMBA */
31 	{} /* Empty terminated list */
32 };
33 
34 static const struct of_device_id of_skipped_node_table[] = {
35 	{ .compatible = "operating-points-v2", },
36 	{} /* Empty terminated list */
37 };
38 
39 /**
40  * of_find_device_by_node - Find the platform_device associated with a node
41  * @np: Pointer to device tree node
42  *
43  * Takes a reference to the embedded struct device which needs to be dropped
44  * after use.
45  *
46  * Return: platform_device pointer, or NULL if not found
47  */
48 struct platform_device *of_find_device_by_node(struct device_node *np)
49 {
50 	struct device *dev;
51 
52 	dev = bus_find_device_by_of_node(&platform_bus_type, np);
53 	return dev ? to_platform_device(dev) : NULL;
54 }
55 EXPORT_SYMBOL(of_find_device_by_node);
56 
57 #ifdef CONFIG_OF_ADDRESS
58 /*
59  * The following routines scan a subtree and registers a device for
60  * each applicable node.
61  *
62  * Note: sparc doesn't use these routines because it has a different
63  * mechanism for creating devices from device tree nodes.
64  */
65 
66 /**
67  * of_device_make_bus_id - Use the device node data to assign a unique name
68  * @dev: pointer to device structure that is linked to a device tree node
69  *
70  * This routine will first try using the translated bus address to
71  * derive a unique name. If it cannot, then it will prepend names from
72  * parent nodes until a unique name can be derived.
73  */
74 static void of_device_make_bus_id(struct device *dev)
75 {
76 	struct device_node *node = dev->of_node;
77 	const __be32 *reg;
78 	u64 addr;
79 	u32 mask;
80 
81 	/* Construct the name, using parent nodes if necessary to ensure uniqueness */
82 	while (node->parent) {
83 		/*
84 		 * If the address can be translated, then that is as much
85 		 * uniqueness as we need. Make it the first component and return
86 		 */
87 		reg = of_get_property(node, "reg", NULL);
88 		if (reg && (addr = of_translate_address(node, reg)) != OF_BAD_ADDR) {
89 			if (!of_property_read_u32(node, "mask", &mask))
90 				dev_set_name(dev, dev_name(dev) ? "%llx.%x.%pOFn:%s" : "%llx.%x.%pOFn",
91 					     addr, ffs(mask) - 1, node, dev_name(dev));
92 
93 			else
94 				dev_set_name(dev, dev_name(dev) ? "%llx.%pOFn:%s" : "%llx.%pOFn",
95 					     addr, node, dev_name(dev));
96 			return;
97 		}
98 
99 		/* format arguments only used if dev_name() resolves to NULL */
100 		dev_set_name(dev, dev_name(dev) ? "%s:%s" : "%s",
101 			     kbasename(node->full_name), dev_name(dev));
102 		node = node->parent;
103 	}
104 }
105 
106 /**
107  * of_device_alloc - Allocate and initialize an of_device
108  * @np: device node to assign to device
109  * @bus_id: Name to assign to the device.  May be null to use default name.
110  * @parent: Parent device.
111  */
112 struct platform_device *of_device_alloc(struct device_node *np,
113 				  const char *bus_id,
114 				  struct device *parent)
115 {
116 	struct platform_device *dev;
117 	int rc, i, num_reg = 0;
118 	struct resource *res, temp_res;
119 
120 	dev = platform_device_alloc("", PLATFORM_DEVID_NONE);
121 	if (!dev)
122 		return NULL;
123 
124 	/* count the io resources */
125 	while (of_address_to_resource(np, num_reg, &temp_res) == 0)
126 		num_reg++;
127 
128 	/* Populate the resource table */
129 	if (num_reg) {
130 		res = kcalloc(num_reg, sizeof(*res), GFP_KERNEL);
131 		if (!res) {
132 			platform_device_put(dev);
133 			return NULL;
134 		}
135 
136 		dev->num_resources = num_reg;
137 		dev->resource = res;
138 		for (i = 0; i < num_reg; i++, res++) {
139 			rc = of_address_to_resource(np, i, res);
140 			WARN_ON(rc);
141 		}
142 	}
143 
144 	dev->dev.of_node = of_node_get(np);
145 	dev->dev.fwnode = &np->fwnode;
146 	dev->dev.parent = parent ? : &platform_bus;
147 
148 	if (bus_id)
149 		dev_set_name(&dev->dev, "%s", bus_id);
150 	else
151 		of_device_make_bus_id(&dev->dev);
152 
153 	return dev;
154 }
155 EXPORT_SYMBOL(of_device_alloc);
156 
157 /**
158  * of_platform_device_create_pdata - Alloc, initialize and register an of_device
159  * @np: pointer to node to create device for
160  * @bus_id: name to assign device
161  * @platform_data: pointer to populate platform_data pointer with
162  * @parent: Linux device model parent device.
163  *
164  * Return: Pointer to created platform device, or NULL if a device was not
165  * registered.  Unavailable devices will not get registered.
166  */
167 static struct platform_device *of_platform_device_create_pdata(
168 					struct device_node *np,
169 					const char *bus_id,
170 					void *platform_data,
171 					struct device *parent)
172 {
173 	struct platform_device *dev;
174 
175 	if (!of_device_is_available(np) ||
176 	    of_node_test_and_set_flag(np, OF_POPULATED))
177 		return NULL;
178 
179 	dev = of_device_alloc(np, bus_id, parent);
180 	if (!dev)
181 		goto err_clear_flag;
182 
183 	dev->dev.coherent_dma_mask = DMA_BIT_MASK(32);
184 	if (!dev->dev.dma_mask)
185 		dev->dev.dma_mask = &dev->dev.coherent_dma_mask;
186 	dev->dev.bus = &platform_bus_type;
187 	dev->dev.platform_data = platform_data;
188 	of_msi_configure(&dev->dev, dev->dev.of_node);
189 
190 	if (of_device_add(dev) != 0) {
191 		platform_device_put(dev);
192 		goto err_clear_flag;
193 	}
194 
195 	return dev;
196 
197 err_clear_flag:
198 	of_node_clear_flag(np, OF_POPULATED);
199 	return NULL;
200 }
201 
202 /**
203  * of_platform_device_create - Alloc, initialize and register an of_device
204  * @np: pointer to node to create device for
205  * @bus_id: name to assign device
206  * @parent: Linux device model parent device.
207  *
208  * Return: Pointer to created platform device, or NULL if a device was not
209  * registered.  Unavailable devices will not get registered.
210  */
211 struct platform_device *of_platform_device_create(struct device_node *np,
212 					    const char *bus_id,
213 					    struct device *parent)
214 {
215 	return of_platform_device_create_pdata(np, bus_id, NULL, parent);
216 }
217 EXPORT_SYMBOL(of_platform_device_create);
218 
219 #ifdef CONFIG_ARM_AMBA
220 static struct amba_device *of_amba_device_create(struct device_node *node,
221 						 const char *bus_id,
222 						 void *platform_data,
223 						 struct device *parent)
224 {
225 	struct amba_device *dev;
226 	const void *prop;
227 	int ret;
228 
229 	pr_debug("Creating amba device %pOF\n", node);
230 
231 	if (!of_device_is_available(node) ||
232 	    of_node_test_and_set_flag(node, OF_POPULATED))
233 		return NULL;
234 
235 	dev = amba_device_alloc(NULL, 0, 0);
236 	if (!dev)
237 		goto err_clear_flag;
238 
239 	/* AMBA devices only support a single DMA mask */
240 	dev->dev.coherent_dma_mask = DMA_BIT_MASK(32);
241 	dev->dev.dma_mask = &dev->dev.coherent_dma_mask;
242 
243 	/* setup generic device info */
244 	dev->dev.of_node = of_node_get(node);
245 	dev->dev.fwnode = &node->fwnode;
246 	dev->dev.parent = parent ? : &platform_bus;
247 	dev->dev.platform_data = platform_data;
248 	if (bus_id)
249 		dev_set_name(&dev->dev, "%s", bus_id);
250 	else
251 		of_device_make_bus_id(&dev->dev);
252 
253 	/* Allow the HW Peripheral ID to be overridden */
254 	prop = of_get_property(node, "arm,primecell-periphid", NULL);
255 	if (prop)
256 		dev->periphid = of_read_ulong(prop, 1);
257 
258 	ret = of_address_to_resource(node, 0, &dev->res);
259 	if (ret) {
260 		pr_err("amba: of_address_to_resource() failed (%d) for %pOF\n",
261 		       ret, node);
262 		goto err_free;
263 	}
264 
265 	ret = amba_device_add(dev, &iomem_resource);
266 	if (ret) {
267 		pr_err("amba_device_add() failed (%d) for %pOF\n",
268 		       ret, node);
269 		goto err_free;
270 	}
271 
272 	return dev;
273 
274 err_free:
275 	amba_device_put(dev);
276 err_clear_flag:
277 	of_node_clear_flag(node, OF_POPULATED);
278 	return NULL;
279 }
280 #else /* CONFIG_ARM_AMBA */
281 static struct amba_device *of_amba_device_create(struct device_node *node,
282 						 const char *bus_id,
283 						 void *platform_data,
284 						 struct device *parent)
285 {
286 	return NULL;
287 }
288 #endif /* CONFIG_ARM_AMBA */
289 
290 /*
291  * of_dev_lookup() - Given a device node, lookup the preferred Linux name
292  */
293 static const struct of_dev_auxdata *of_dev_lookup(const struct of_dev_auxdata *lookup,
294 				 struct device_node *np)
295 {
296 	const struct of_dev_auxdata *auxdata;
297 	struct resource res;
298 	int compatible = 0;
299 
300 	if (!lookup)
301 		return NULL;
302 
303 	auxdata = lookup;
304 	for (; auxdata->compatible; auxdata++) {
305 		if (!of_device_is_compatible(np, auxdata->compatible))
306 			continue;
307 		compatible++;
308 		if (!of_address_to_resource(np, 0, &res))
309 			if (res.start != auxdata->phys_addr)
310 				continue;
311 		pr_debug("%pOF: devname=%s\n", np, auxdata->name);
312 		return auxdata;
313 	}
314 
315 	if (!compatible)
316 		return NULL;
317 
318 	/* Try compatible match if no phys_addr and name are specified */
319 	auxdata = lookup;
320 	for (; auxdata->compatible; auxdata++) {
321 		if (!of_device_is_compatible(np, auxdata->compatible))
322 			continue;
323 		if (!auxdata->phys_addr && !auxdata->name) {
324 			pr_debug("%pOF: compatible match\n", np);
325 			return auxdata;
326 		}
327 	}
328 
329 	return NULL;
330 }
331 
332 /**
333  * of_platform_bus_create() - Create a device for a node and its children.
334  * @bus: device node of the bus to instantiate
335  * @matches: match table for bus nodes
336  * @lookup: auxdata table for matching id and platform_data with device nodes
337  * @parent: parent for new device, or NULL for top level.
338  * @strict: require compatible property
339  *
340  * Creates a platform_device for the provided device_node, and optionally
341  * recursively create devices for all the child nodes.
342  */
343 static int of_platform_bus_create(struct device_node *bus,
344 				  const struct of_device_id *matches,
345 				  const struct of_dev_auxdata *lookup,
346 				  struct device *parent, bool strict)
347 {
348 	const struct of_dev_auxdata *auxdata;
349 	struct device_node *child;
350 	struct platform_device *dev;
351 	const char *bus_id = NULL;
352 	void *platform_data = NULL;
353 	int rc = 0;
354 
355 	/* Make sure it has a compatible property */
356 	if (strict && (!of_get_property(bus, "compatible", NULL))) {
357 		pr_debug("%s() - skipping %pOF, no compatible prop\n",
358 			 __func__, bus);
359 		return 0;
360 	}
361 
362 	/* Skip nodes for which we don't want to create devices */
363 	if (unlikely(of_match_node(of_skipped_node_table, bus))) {
364 		pr_debug("%s() - skipping %pOF node\n", __func__, bus);
365 		return 0;
366 	}
367 
368 	if (of_node_check_flag(bus, OF_POPULATED_BUS)) {
369 		pr_debug("%s() - skipping %pOF, already populated\n",
370 			__func__, bus);
371 		return 0;
372 	}
373 
374 	auxdata = of_dev_lookup(lookup, bus);
375 	if (auxdata) {
376 		bus_id = auxdata->name;
377 		platform_data = auxdata->platform_data;
378 	}
379 
380 	if (of_device_is_compatible(bus, "arm,primecell")) {
381 		/*
382 		 * Don't return an error here to keep compatibility with older
383 		 * device tree files.
384 		 */
385 		of_amba_device_create(bus, bus_id, platform_data, parent);
386 		return 0;
387 	}
388 
389 	dev = of_platform_device_create_pdata(bus, bus_id, platform_data, parent);
390 	if (!dev || !of_match_node(matches, bus))
391 		return 0;
392 
393 	for_each_child_of_node(bus, child) {
394 		pr_debug("   create child: %pOF\n", child);
395 		rc = of_platform_bus_create(child, matches, lookup, &dev->dev, strict);
396 		if (rc) {
397 			of_node_put(child);
398 			break;
399 		}
400 	}
401 	of_node_set_flag(bus, OF_POPULATED_BUS);
402 	return rc;
403 }
404 
405 /**
406  * of_platform_bus_probe() - Probe the device-tree for platform buses
407  * @root: parent of the first level to probe or NULL for the root of the tree
408  * @matches: match table for bus nodes
409  * @parent: parent to hook devices from, NULL for toplevel
410  *
411  * Note that children of the provided root are not instantiated as devices
412  * unless the specified root itself matches the bus list and is not NULL.
413  */
414 int of_platform_bus_probe(struct device_node *root,
415 			  const struct of_device_id *matches,
416 			  struct device *parent)
417 {
418 	struct device_node *child;
419 	int rc = 0;
420 
421 	root = root ? of_node_get(root) : of_find_node_by_path("/");
422 	if (!root)
423 		return -EINVAL;
424 
425 	pr_debug("%s()\n", __func__);
426 	pr_debug(" starting at: %pOF\n", root);
427 
428 	/* Do a self check of bus type, if there's a match, create children */
429 	if (of_match_node(matches, root)) {
430 		rc = of_platform_bus_create(root, matches, NULL, parent, false);
431 	} else for_each_child_of_node(root, child) {
432 		if (!of_match_node(matches, child))
433 			continue;
434 		rc = of_platform_bus_create(child, matches, NULL, parent, false);
435 		if (rc) {
436 			of_node_put(child);
437 			break;
438 		}
439 	}
440 
441 	of_node_put(root);
442 	return rc;
443 }
444 EXPORT_SYMBOL(of_platform_bus_probe);
445 
446 /**
447  * of_platform_populate() - Populate platform_devices from device tree data
448  * @root: parent of the first level to probe or NULL for the root of the tree
449  * @matches: match table, NULL to use the default
450  * @lookup: auxdata table for matching id and platform_data with device nodes
451  * @parent: parent to hook devices from, NULL for toplevel
452  *
453  * Similar to of_platform_bus_probe(), this function walks the device tree
454  * and creates devices from nodes.  It differs in that it follows the modern
455  * convention of requiring all device nodes to have a 'compatible' property,
456  * and it is suitable for creating devices which are children of the root
457  * node (of_platform_bus_probe will only create children of the root which
458  * are selected by the @matches argument).
459  *
460  * New board support should be using this function instead of
461  * of_platform_bus_probe().
462  *
463  * Return: 0 on success, < 0 on failure.
464  */
465 int of_platform_populate(struct device_node *root,
466 			const struct of_device_id *matches,
467 			const struct of_dev_auxdata *lookup,
468 			struct device *parent)
469 {
470 	struct device_node *child;
471 	int rc = 0;
472 
473 	root = root ? of_node_get(root) : of_find_node_by_path("/");
474 	if (!root)
475 		return -EINVAL;
476 
477 	pr_debug("%s()\n", __func__);
478 	pr_debug(" starting at: %pOF\n", root);
479 
480 	device_links_supplier_sync_state_pause();
481 	for_each_child_of_node(root, child) {
482 		rc = of_platform_bus_create(child, matches, lookup, parent, true);
483 		if (rc) {
484 			of_node_put(child);
485 			break;
486 		}
487 	}
488 	device_links_supplier_sync_state_resume();
489 
490 	of_node_set_flag(root, OF_POPULATED_BUS);
491 
492 	of_node_put(root);
493 	return rc;
494 }
495 EXPORT_SYMBOL_GPL(of_platform_populate);
496 
497 int of_platform_default_populate(struct device_node *root,
498 				 const struct of_dev_auxdata *lookup,
499 				 struct device *parent)
500 {
501 	return of_platform_populate(root, of_default_bus_match_table, lookup,
502 				    parent);
503 }
504 EXPORT_SYMBOL_GPL(of_platform_default_populate);
505 
506 static const struct of_device_id reserved_mem_matches[] = {
507 	{ .compatible = "phram" },
508 	{ .compatible = "qcom,rmtfs-mem" },
509 	{ .compatible = "qcom,cmd-db" },
510 	{ .compatible = "qcom,smem" },
511 	{ .compatible = "ramoops" },
512 	{ .compatible = "nvmem-rmem" },
513 	{ .compatible = "google,open-dice" },
514 	{}
515 };
516 
517 static int __init of_platform_default_populate_init(void)
518 {
519 	struct device_node *node;
520 
521 	device_links_supplier_sync_state_pause();
522 
523 	if (!of_have_populated_dt())
524 		return -ENODEV;
525 
526 	if (IS_ENABLED(CONFIG_PPC)) {
527 		struct device_node *boot_display = NULL;
528 		struct platform_device *dev;
529 		int ret;
530 
531 		/* Check if we have a MacOS display without a node spec */
532 		if (of_get_property(of_chosen, "linux,bootx-noscreen", NULL)) {
533 			/*
534 			 * The old code tried to work out which node was the MacOS
535 			 * display based on the address. I'm dropping that since the
536 			 * lack of a node spec only happens with old BootX versions
537 			 * (users can update) and with this code, they'll still get
538 			 * a display (just not the palette hacks).
539 			 */
540 			dev = platform_device_alloc("bootx-noscreen", 0);
541 			if (WARN_ON(!dev))
542 				return -ENOMEM;
543 			ret = platform_device_add(dev);
544 			if (WARN_ON(ret)) {
545 				platform_device_put(dev);
546 				return ret;
547 			}
548 		}
549 
550 		/*
551 		 * For OF framebuffers, first create the device for the boot display,
552 		 * then for the other framebuffers. Only fail for the boot display;
553 		 * ignore errors for the rest.
554 		 */
555 		for_each_node_by_type(node, "display") {
556 			if (!of_get_property(node, "linux,opened", NULL) ||
557 			    !of_get_property(node, "linux,boot-display", NULL))
558 				continue;
559 			dev = of_platform_device_create(node, "of-display", NULL);
560 			if (WARN_ON(!dev))
561 				return -ENOMEM;
562 			boot_display = node;
563 			break;
564 		}
565 		for_each_node_by_type(node, "display") {
566 			if (!of_get_property(node, "linux,opened", NULL) || node == boot_display)
567 				continue;
568 			of_platform_device_create(node, "of-display", NULL);
569 		}
570 
571 	} else {
572 		/*
573 		 * Handle certain compatibles explicitly, since we don't want to create
574 		 * platform_devices for every node in /reserved-memory with a
575 		 * "compatible",
576 		 */
577 		for_each_matching_node(node, reserved_mem_matches)
578 			of_platform_device_create(node, NULL, NULL);
579 
580 		node = of_find_node_by_path("/firmware");
581 		if (node) {
582 			of_platform_populate(node, NULL, NULL, NULL);
583 			of_node_put(node);
584 		}
585 
586 		node = of_get_compatible_child(of_chosen, "simple-framebuffer");
587 		of_platform_device_create(node, NULL, NULL);
588 		of_node_put(node);
589 
590 		/* Populate everything else. */
591 		of_platform_default_populate(NULL, NULL, NULL);
592 	}
593 
594 	return 0;
595 }
596 arch_initcall_sync(of_platform_default_populate_init);
597 
598 static int __init of_platform_sync_state_init(void)
599 {
600 	device_links_supplier_sync_state_resume();
601 	return 0;
602 }
603 late_initcall_sync(of_platform_sync_state_init);
604 
605 int of_platform_device_destroy(struct device *dev, void *data)
606 {
607 	/* Do not touch devices not populated from the device tree */
608 	if (!dev->of_node || !of_node_check_flag(dev->of_node, OF_POPULATED))
609 		return 0;
610 
611 	/* Recurse for any nodes that were treated as busses */
612 	if (of_node_check_flag(dev->of_node, OF_POPULATED_BUS))
613 		device_for_each_child(dev, NULL, of_platform_device_destroy);
614 
615 	of_node_clear_flag(dev->of_node, OF_POPULATED);
616 	of_node_clear_flag(dev->of_node, OF_POPULATED_BUS);
617 
618 	if (dev->bus == &platform_bus_type)
619 		platform_device_unregister(to_platform_device(dev));
620 #ifdef CONFIG_ARM_AMBA
621 	else if (dev->bus == &amba_bustype)
622 		amba_device_unregister(to_amba_device(dev));
623 #endif
624 
625 	return 0;
626 }
627 EXPORT_SYMBOL_GPL(of_platform_device_destroy);
628 
629 /**
630  * of_platform_depopulate() - Remove devices populated from device tree
631  * @parent: device which children will be removed
632  *
633  * Complementary to of_platform_populate(), this function removes children
634  * of the given device (and, recurrently, their children) that have been
635  * created from their respective device tree nodes (and only those,
636  * leaving others - eg. manually created - unharmed).
637  */
638 void of_platform_depopulate(struct device *parent)
639 {
640 	if (parent->of_node && of_node_check_flag(parent->of_node, OF_POPULATED_BUS)) {
641 		device_for_each_child_reverse(parent, NULL, of_platform_device_destroy);
642 		of_node_clear_flag(parent->of_node, OF_POPULATED_BUS);
643 	}
644 }
645 EXPORT_SYMBOL_GPL(of_platform_depopulate);
646 
647 static void devm_of_platform_populate_release(struct device *dev, void *res)
648 {
649 	of_platform_depopulate(*(struct device **)res);
650 }
651 
652 /**
653  * devm_of_platform_populate() - Populate platform_devices from device tree data
654  * @dev: device that requested to populate from device tree data
655  *
656  * Similar to of_platform_populate(), but will automatically call
657  * of_platform_depopulate() when the device is unbound from the bus.
658  *
659  * Return: 0 on success, < 0 on failure.
660  */
661 int devm_of_platform_populate(struct device *dev)
662 {
663 	struct device **ptr;
664 	int ret;
665 
666 	if (!dev)
667 		return -EINVAL;
668 
669 	ptr = devres_alloc(devm_of_platform_populate_release,
670 			   sizeof(*ptr), GFP_KERNEL);
671 	if (!ptr)
672 		return -ENOMEM;
673 
674 	ret = of_platform_populate(dev->of_node, NULL, NULL, dev);
675 	if (ret) {
676 		devres_free(ptr);
677 	} else {
678 		*ptr = dev;
679 		devres_add(dev, ptr);
680 	}
681 
682 	return ret;
683 }
684 EXPORT_SYMBOL_GPL(devm_of_platform_populate);
685 
686 static int devm_of_platform_match(struct device *dev, void *res, void *data)
687 {
688 	struct device **ptr = res;
689 
690 	if (!ptr) {
691 		WARN_ON(!ptr);
692 		return 0;
693 	}
694 
695 	return *ptr == data;
696 }
697 
698 /**
699  * devm_of_platform_depopulate() - Remove devices populated from device tree
700  * @dev: device that requested to depopulate from device tree data
701  *
702  * Complementary to devm_of_platform_populate(), this function removes children
703  * of the given device (and, recurrently, their children) that have been
704  * created from their respective device tree nodes (and only those,
705  * leaving others - eg. manually created - unharmed).
706  */
707 void devm_of_platform_depopulate(struct device *dev)
708 {
709 	int ret;
710 
711 	ret = devres_release(dev, devm_of_platform_populate_release,
712 			     devm_of_platform_match, dev);
713 
714 	WARN_ON(ret);
715 }
716 EXPORT_SYMBOL_GPL(devm_of_platform_depopulate);
717 
718 #ifdef CONFIG_OF_DYNAMIC
719 static int of_platform_notify(struct notifier_block *nb,
720 				unsigned long action, void *arg)
721 {
722 	struct of_reconfig_data *rd = arg;
723 	struct platform_device *pdev_parent, *pdev;
724 	bool children_left;
725 
726 	switch (of_reconfig_get_state_change(action, rd)) {
727 	case OF_RECONFIG_CHANGE_ADD:
728 		/* verify that the parent is a bus */
729 		if (!of_node_check_flag(rd->dn->parent, OF_POPULATED_BUS))
730 			return NOTIFY_OK;	/* not for us */
731 
732 		/* already populated? (driver using of_populate manually) */
733 		if (of_node_check_flag(rd->dn, OF_POPULATED))
734 			return NOTIFY_OK;
735 
736 		/* pdev_parent may be NULL when no bus platform device */
737 		pdev_parent = of_find_device_by_node(rd->dn->parent);
738 		pdev = of_platform_device_create(rd->dn, NULL,
739 				pdev_parent ? &pdev_parent->dev : NULL);
740 		platform_device_put(pdev_parent);
741 
742 		if (pdev == NULL) {
743 			pr_err("%s: failed to create for '%pOF'\n",
744 					__func__, rd->dn);
745 			/* of_platform_device_create tosses the error code */
746 			return notifier_from_errno(-EINVAL);
747 		}
748 		break;
749 
750 	case OF_RECONFIG_CHANGE_REMOVE:
751 
752 		/* already depopulated? */
753 		if (!of_node_check_flag(rd->dn, OF_POPULATED))
754 			return NOTIFY_OK;
755 
756 		/* find our device by node */
757 		pdev = of_find_device_by_node(rd->dn);
758 		if (pdev == NULL)
759 			return NOTIFY_OK;	/* no? not meant for us */
760 
761 		/* unregister takes one ref away */
762 		of_platform_device_destroy(&pdev->dev, &children_left);
763 
764 		/* and put the reference of the find */
765 		platform_device_put(pdev);
766 		break;
767 	}
768 
769 	return NOTIFY_OK;
770 }
771 
772 static struct notifier_block platform_of_notifier = {
773 	.notifier_call = of_platform_notify,
774 };
775 
776 void of_platform_register_reconfig_notifier(void)
777 {
778 	WARN_ON(of_reconfig_notifier_register(&platform_of_notifier));
779 }
780 #endif /* CONFIG_OF_DYNAMIC */
781 
782 #endif /* CONFIG_OF_ADDRESS */
783