drivers/of/of_reserved_mem.c - linux - Git at Google

 // SPDX-License-Identifier: GPL-2.0+
 /*
  * Device tree based initialization code for reserved memory.
  *
  * Copyright (c) 2013, 2015 The Linux Foundation. All Rights Reserved.
  * Copyright (c) 2013,2014 Samsung Electronics Co., Ltd.
  *		http://www.samsung.com
  * Author: Marek Szyprowski <m.szyprowski@samsung.com>
  * Author: Josh Cartwright <joshc@codeaurora.org>
  */

 #define pr_fmt(fmt)	"OF: reserved mem: " fmt

 #include <linux/err.h>
 #include <linux/of.h>
 #include <linux/of_fdt.h>
 #include <linux/of_platform.h>
 #include <linux/mm.h>
 #include <linux/sizes.h>
 #include <linux/of_reserved_mem.h>
 #include <linux/sort.h>
 #include <linux/slab.h>
 #include <linux/memblock.h>
 #include <linux/kmemleak.h>
 #include <linux/cma.h>

 #include "of_private.h"

 #define MAX_RESERVED_REGIONS	128
 static struct reserved_mem reserved_mem[MAX_RESERVED_REGIONS];
 static int reserved_mem_count;

 static int __init early_init_dt_alloc_reserved_memory_arch(phys_addr_t size,
 	phys_addr_t align, phys_addr_t start, phys_addr_t end, bool nomap,
 	phys_addr_t *res_base)
 {
 	phys_addr_t base;
 	int err = 0;

 	end = !end ? MEMBLOCK_ALLOC_ANYWHERE : end;
 	align = !align ? SMP_CACHE_BYTES : align;
 	base = memblock_phys_alloc_range(size, align, start, end);
 	if (!base)
 		return -ENOMEM;

 	*res_base = base;
 	if (nomap) {
 		err = memblock_mark_nomap(base, size);
 		if (err)
 			memblock_phys_free(base, size);
 	}

 	kmemleak_ignore_phys(base);

 	return err;
 }

 /*
  * fdt_reserved_mem_save_node() - save fdt node for second pass initialization
  */
 void __init fdt_reserved_mem_save_node(unsigned long node, const char *uname,
 				      phys_addr_t base, phys_addr_t size)
 {
 	struct reserved_mem *rmem = &reserved_mem[reserved_mem_count];

 	if (reserved_mem_count == ARRAY_SIZE(reserved_mem)) {
 		pr_err("not enough space for all defined regions.\n");
 		return;
 	}

 	rmem->fdt_node = node;
 	rmem->name = uname;
 	rmem->base = base;
 	rmem->size = size;

 	reserved_mem_count++;
 	return;
 }

 /*
  * __reserved_mem_alloc_size() - allocate reserved memory described by
  *	'size', 'alignment'  and 'alloc-ranges' properties.
  */
 static int __init __reserved_mem_alloc_size(unsigned long node,
 	const char *uname, phys_addr_t *res_base, phys_addr_t *res_size)
 {
 	int t_len = (dt_root_addr_cells + dt_root_size_cells) * sizeof(__be32);
 	phys_addr_t start = 0, end = 0;
 	phys_addr_t base = 0, align = 0, size;
 	int len;
 	const __be32 *prop;
 	bool nomap;
 	int ret;

 	prop = of_get_flat_dt_prop(node, "size", &len);
 	if (!prop)
 		return -EINVAL;

 	if (len != dt_root_size_cells * sizeof(__be32)) {
 		pr_err("invalid size property in '%s' node.\n", uname);
 		return -EINVAL;
 	}
 	size = dt_mem_next_cell(dt_root_size_cells, &prop);

 	prop = of_get_flat_dt_prop(node, "alignment", &len);
 	if (prop) {
 		if (len != dt_root_addr_cells * sizeof(__be32)) {
 			pr_err("invalid alignment property in '%s' node.\n",
 				uname);
 			return -EINVAL;
 		}
 		align = dt_mem_next_cell(dt_root_addr_cells, &prop);
 	}

 	nomap = of_get_flat_dt_prop(node, "no-map", NULL) != NULL;

 	/* Need adjust the alignment to satisfy the CMA requirement */
 	if (IS_ENABLED(CONFIG_CMA)
 	    && of_flat_dt_is_compatible(node, "shared-dma-pool")
 	    && of_get_flat_dt_prop(node, "reusable", NULL)
 	    && !nomap)
 		align = max_t(phys_addr_t, align, CMA_MIN_ALIGNMENT_BYTES);

 	prop = of_get_flat_dt_prop(node, "alloc-ranges", &len);
 	if (prop) {

 		if (len % t_len != 0) {
 			pr_err("invalid alloc-ranges property in '%s', skipping node.\n",
 			       uname);
 			return -EINVAL;
 		}

 		base = 0;

 		while (len > 0) {
 			start = dt_mem_next_cell(dt_root_addr_cells, &prop);
 			end = start + dt_mem_next_cell(dt_root_size_cells,
 						       &prop);

 			ret = early_init_dt_alloc_reserved_memory_arch(size,
 					align, start, end, nomap, &base);
 			if (ret == 0) {
 				pr_debug("allocated memory for '%s' node: base %pa, size %lu MiB\n",
 					uname, &base,
 					(unsigned long)(size / SZ_1M));
 				break;
 			}
 			len -= t_len;
 		}

 	} else {
 		ret = early_init_dt_alloc_reserved_memory_arch(size, align,
 							0, 0, nomap, &base);
 		if (ret == 0)
 			pr_debug("allocated memory for '%s' node: base %pa, size %lu MiB\n",
 				uname, &base, (unsigned long)(size / SZ_1M));
 	}

 	if (base == 0) {
 		pr_err("failed to allocate memory for node '%s': size %lu MiB\n",
 		       uname, (unsigned long)(size / SZ_1M));
 		return -ENOMEM;
 	}

 	*res_base = base;
 	*res_size = size;

 	return 0;
 }

 static const struct of_device_id __rmem_of_table_sentinel
 	__used __section("__reservedmem_of_table_end");

 /*
  * __reserved_mem_init_node() - call region specific reserved memory init code
  */
 static int __init __reserved_mem_init_node(struct reserved_mem *rmem)
 {
 	extern const struct of_device_id __reservedmem_of_table[];
 	const struct of_device_id *i;
 	int ret = -ENOENT;

 	for (i = __reservedmem_of_table; i < &__rmem_of_table_sentinel; i++) {
 		reservedmem_of_init_fn initfn = i->data;
 		const char *compat = i->compatible;

 		if (!of_flat_dt_is_compatible(rmem->fdt_node, compat))
 			continue;

 		ret = initfn(rmem);
 		if (ret == 0) {
 			pr_info("initialized node %s, compatible id %s\n",
 				rmem->name, compat);
 			break;
 		}
 	}
 	return ret;
 }

 static int __init __rmem_cmp(const void *a, const void *b)
 {
 	const struct reserved_mem *ra = a, *rb = b;

 	if (ra->base < rb->base)
 		return -1;

 	if (ra->base > rb->base)
 		return 1;

 	/*
 	 * Put the dynamic allocations (address == 0, size == 0) before static
 	 * allocations at address 0x0 so that overlap detection works
 	 * correctly.
 	 */
 	if (ra->size < rb->size)
 		return -1;
 	if (ra->size > rb->size)
 		return 1;

 	return 0;
 }

 static void __init __rmem_check_for_overlap(void)
 {
 	int i;

 	if (reserved_mem_count < 2)
 		return;

 	sort(reserved_mem, reserved_mem_count, sizeof(reserved_mem[0]),
 	     __rmem_cmp, NULL);
 	for (i = 0; i < reserved_mem_count - 1; i++) {
 		struct reserved_mem *this, *next;

 		this = &reserved_mem[i];
 		next = &reserved_mem[i + 1];

 		if (this->base + this->size > next->base) {
 			phys_addr_t this_end, next_end;

 			this_end = this->base + this->size;
 			next_end = next->base + next->size;
 			pr_err("OVERLAP DETECTED!\n%s (%pa--%pa) overlaps with %s (%pa--%pa)\n",
 			       this->name, &this->base, &this_end,
 			       next->name, &next->base, &next_end);
 		}
 	}
 }

 /**
  * fdt_init_reserved_mem() - allocate and init all saved reserved memory regions
  */
 void __init fdt_init_reserved_mem(void)
 {
 	int i;

 	/* check for overlapping reserved regions */
 	__rmem_check_for_overlap();

 	for (i = 0; i < reserved_mem_count; i++) {
 		struct reserved_mem *rmem = &reserved_mem[i];
 		unsigned long node = rmem->fdt_node;
 		int len;
 		const __be32 *prop;
 		int err = 0;
 		bool nomap;

 		nomap = of_get_flat_dt_prop(node, "no-map", NULL) != NULL;
 		prop = of_get_flat_dt_prop(node, "phandle", &len);
 		if (!prop)
 			prop = of_get_flat_dt_prop(node, "linux,phandle", &len);
 		if (prop)
 			rmem->phandle = of_read_number(prop, len/4);

 		if (rmem->size == 0)
 			err = __reserved_mem_alloc_size(node, rmem->name,
 						 &rmem->base, &rmem->size);
 		if (err == 0) {
 			err = __reserved_mem_init_node(rmem);
 			if (err != 0 && err != -ENOENT) {
 				pr_info("node %s compatible matching fail\n",
 					rmem->name);
 				if (nomap)
 					memblock_clear_nomap(rmem->base, rmem->size);
 				else
 					memblock_phys_free(rmem->base,
 							   rmem->size);
 			} else {
 				phys_addr_t end = rmem->base + rmem->size - 1;
 				bool reusable =
 					(of_get_flat_dt_prop(node, "reusable", NULL)) != NULL;

 				pr_info("%pa..%pa ( %lu KB ) %s %s %s\n",
 					&rmem->base, &end, (unsigned long)(rmem->size / SZ_1K),
 					nomap ? "nomap" : "map",
 					reusable ? "reusable" : "non-reusable",
 					rmem->name ? rmem->name : "unknown");
 			}
 		}
 	}
 }

 static inline struct reserved_mem *__find_rmem(struct device_node *node)
 {
 	unsigned int i;

 	if (!node->phandle)
 		return NULL;

 	for (i = 0; i < reserved_mem_count; i++)
 		if (reserved_mem[i].phandle == node->phandle)
 			return &reserved_mem[i];
 	return NULL;
 }

 struct rmem_assigned_device {
 	struct device *dev;
 	struct reserved_mem *rmem;
 	struct list_head list;
 };

 static LIST_HEAD(of_rmem_assigned_device_list);
 static DEFINE_MUTEX(of_rmem_assigned_device_mutex);

 /**
  * of_reserved_mem_device_init_by_idx() - assign reserved memory region to
  *					  given device
  * @dev:	Pointer to the device to configure
  * @np:		Pointer to the device_node with 'reserved-memory' property
  * @idx:	Index of selected region
  *
  * This function assigns respective DMA-mapping operations based on reserved
  * memory region specified by 'memory-region' property in @np node to the @dev
  * device. When driver needs to use more than one reserved memory region, it
  * should allocate child devices and initialize regions by name for each of
  * child device.
  *
  * Returns error code or zero on success.
  */
 int of_reserved_mem_device_init_by_idx(struct device *dev,
 				       struct device_node *np, int idx)
 {
 	struct rmem_assigned_device *rd;
 	struct device_node *target;
 	struct reserved_mem *rmem;
 	int ret;

 	if (!np || !dev)
 		return -EINVAL;

 	target = of_parse_phandle(np, "memory-region", idx);
 	if (!target)
 		return -ENODEV;

 	if (!of_device_is_available(target)) {
 		of_node_put(target);
 		return 0;
 	}

 	rmem = __find_rmem(target);
 	of_node_put(target);

 	if (!rmem || !rmem->ops || !rmem->ops->device_init)
 		return -EINVAL;

 	rd = kmalloc(sizeof(struct rmem_assigned_device), GFP_KERNEL);
 	if (!rd)
 		return -ENOMEM;

 	ret = rmem->ops->device_init(rmem, dev);
 	if (ret == 0) {
 		rd->dev = dev;
 		rd->rmem = rmem;

 		mutex_lock(&of_rmem_assigned_device_mutex);
 		list_add(&rd->list, &of_rmem_assigned_device_list);
 		mutex_unlock(&of_rmem_assigned_device_mutex);

 		dev_info(dev, "assigned reserved memory node %s\n", rmem->name);
 	} else {
 		kfree(rd);
 	}

 	return ret;
 }
 EXPORT_SYMBOL_GPL(of_reserved_mem_device_init_by_idx);

 /**
  * of_reserved_mem_device_init_by_name() - assign named reserved memory region
  *					   to given device
  * @dev: pointer to the device to configure
  * @np: pointer to the device node with 'memory-region' property
  * @name: name of the selected memory region
  *
  * Returns: 0 on success or a negative error-code on failure.
  */
 int of_reserved_mem_device_init_by_name(struct device *dev,
 					struct device_node *np,
 					const char *name)
 {
 	int idx = of_property_match_string(np, "memory-region-names", name);

 	return of_reserved_mem_device_init_by_idx(dev, np, idx);
 }
 EXPORT_SYMBOL_GPL(of_reserved_mem_device_init_by_name);

 /**
  * of_reserved_mem_device_release() - release reserved memory device structures
  * @dev:	Pointer to the device to deconfigure
  *
  * This function releases structures allocated for memory region handling for
  * the given device.
  */
 void of_reserved_mem_device_release(struct device *dev)
 {
 	struct rmem_assigned_device *rd, *tmp;
 	LIST_HEAD(release_list);

 	mutex_lock(&of_rmem_assigned_device_mutex);
 	list_for_each_entry_safe(rd, tmp, &of_rmem_assigned_device_list, list) {
 		if (rd->dev == dev)
 			list_move_tail(&rd->list, &release_list);
 	}
 	mutex_unlock(&of_rmem_assigned_device_mutex);

 	list_for_each_entry_safe(rd, tmp, &release_list, list) {
 		if (rd->rmem && rd->rmem->ops && rd->rmem->ops->device_release)
 			rd->rmem->ops->device_release(rd->rmem, dev);

 		kfree(rd);
 	}
 }
 EXPORT_SYMBOL_GPL(of_reserved_mem_device_release);

 /**
  * of_reserved_mem_lookup() - acquire reserved_mem from a device node
  * @np:		node pointer of the desired reserved-memory region
  *
  * This function allows drivers to acquire a reference to the reserved_mem
  * struct based on a device node handle.
  *
  * Returns a reserved_mem reference, or NULL on error.
  */
 struct reserved_mem *of_reserved_mem_lookup(struct device_node *np)
 {
 	const char *name;
 	int i;

 	if (!np->full_name)
 		return NULL;

 	name = kbasename(np->full_name);
 	for (i = 0; i < reserved_mem_count; i++)
 		if (!strcmp(reserved_mem[i].name, name))
 			return &reserved_mem[i];

 	return NULL;
 }
 EXPORT_SYMBOL_GPL(of_reserved_mem_lookup);
	// SPDX-License-Identifier: GPL-2.0+
	/*
	* Device tree based initialization code for reserved memory.
	*
	* Copyright (c) 2013, 2015 The Linux Foundation. All Rights Reserved.
	* Copyright (c) 2013,2014 Samsung Electronics Co., Ltd.
	* http://www.samsung.com
	* Author: Marek Szyprowski <m.szyprowski@samsung.com>
	* Author: Josh Cartwright <joshc@codeaurora.org>
	*/

	#define pr_fmt(fmt) "OF: reserved mem: " fmt

	#include <linux/err.h>
	#include <linux/of.h>
	#include <linux/of_fdt.h>
	#include <linux/of_platform.h>
	#include <linux/mm.h>
	#include <linux/sizes.h>
	#include <linux/of_reserved_mem.h>
	#include <linux/sort.h>
	#include <linux/slab.h>
	#include <linux/memblock.h>
	#include <linux/kmemleak.h>
	#include <linux/cma.h>

	#include "of_private.h"

	#define MAX_RESERVED_REGIONS 128
	static struct reserved_mem reserved_mem[MAX_RESERVED_REGIONS];
	static int reserved_mem_count;

	static int __init early_init_dt_alloc_reserved_memory_arch(phys_addr_t size,
	phys_addr_t align, phys_addr_t start, phys_addr_t end, bool nomap,
	phys_addr_t *res_base)
	{
	phys_addr_t base;
	int err = 0;

	end = !end ? MEMBLOCK_ALLOC_ANYWHERE : end;
	align = !align ? SMP_CACHE_BYTES : align;
	base = memblock_phys_alloc_range(size, align, start, end);
	if (!base)
	return -ENOMEM;

	*res_base = base;
	if (nomap) {
	err = memblock_mark_nomap(base, size);
	if (err)
	memblock_phys_free(base, size);
	}

	kmemleak_ignore_phys(base);

	return err;
	}

	/*
	* fdt_reserved_mem_save_node() - save fdt node for second pass initialization
	*/
	void __init fdt_reserved_mem_save_node(unsigned long node, const char *uname,
	phys_addr_t base, phys_addr_t size)
	{
	struct reserved_mem *rmem = &reserved_mem[reserved_mem_count];

	if (reserved_mem_count == ARRAY_SIZE(reserved_mem)) {
	pr_err("not enough space for all defined regions.\n");
	return;
	}

	rmem->fdt_node = node;
	rmem->name = uname;
	rmem->base = base;
	rmem->size = size;

	reserved_mem_count++;
	return;
	}

	/*
	* __reserved_mem_alloc_size() - allocate reserved memory described by
	* 'size', 'alignment' and 'alloc-ranges' properties.
	*/
	static int __init __reserved_mem_alloc_size(unsigned long node,
	const char uname, phys_addr_t res_base, phys_addr_t *res_size)
	{
	int t_len = (dt_root_addr_cells + dt_root_size_cells) * sizeof(__be32);
	phys_addr_t start = 0, end = 0;
	phys_addr_t base = 0, align = 0, size;
	int len;
	const __be32 *prop;
	bool nomap;
	int ret;

	prop = of_get_flat_dt_prop(node, "size", &len);
	if (!prop)
	return -EINVAL;

	if (len != dt_root_size_cells * sizeof(__be32)) {
	pr_err("invalid size property in '%s' node.\n", uname);
	return -EINVAL;
	}
	size = dt_mem_next_cell(dt_root_size_cells, &prop);

	prop = of_get_flat_dt_prop(node, "alignment", &len);
	if (prop) {
	if (len != dt_root_addr_cells * sizeof(__be32)) {
	pr_err("invalid alignment property in '%s' node.\n",
	uname);
	return -EINVAL;
	}
	align = dt_mem_next_cell(dt_root_addr_cells, &prop);
	}

	nomap = of_get_flat_dt_prop(node, "no-map", NULL) != NULL;

	/* Need adjust the alignment to satisfy the CMA requirement */
	if (IS_ENABLED(CONFIG_CMA)
	&& of_flat_dt_is_compatible(node, "shared-dma-pool")
	&& of_get_flat_dt_prop(node, "reusable", NULL)
	&& !nomap)
	align = max_t(phys_addr_t, align, CMA_MIN_ALIGNMENT_BYTES);

	prop = of_get_flat_dt_prop(node, "alloc-ranges", &len);
	if (prop) {

	if (len % t_len != 0) {
	pr_err("invalid alloc-ranges property in '%s', skipping node.\n",
	uname);
	return -EINVAL;
	}

	base = 0;

	while (len > 0) {
	start = dt_mem_next_cell(dt_root_addr_cells, &prop);
	end = start + dt_mem_next_cell(dt_root_size_cells,
	&prop);

	ret = early_init_dt_alloc_reserved_memory_arch(size,
	align, start, end, nomap, &base);
	if (ret == 0) {
	pr_debug("allocated memory for '%s' node: base %pa, size %lu MiB\n",
	uname, &base,
	(unsigned long)(size / SZ_1M));
	break;
	}
	len -= t_len;
	}

	} else {
	ret = early_init_dt_alloc_reserved_memory_arch(size, align,
	0, 0, nomap, &base);
	if (ret == 0)
	pr_debug("allocated memory for '%s' node: base %pa, size %lu MiB\n",
	uname, &base, (unsigned long)(size / SZ_1M));
	}

	if (base == 0) {
	pr_err("failed to allocate memory for node '%s': size %lu MiB\n",
	uname, (unsigned long)(size / SZ_1M));
	return -ENOMEM;
	}

	*res_base = base;
	*res_size = size;

	return 0;
	}

	static const struct of_device_id __rmem_of_table_sentinel
	__used __section("__reservedmem_of_table_end");

	/*
	* __reserved_mem_init_node() - call region specific reserved memory init code
	*/
	static int __init __reserved_mem_init_node(struct reserved_mem *rmem)
	{
	extern const struct of_device_id __reservedmem_of_table[];
	const struct of_device_id *i;
	int ret = -ENOENT;

	for (i = __reservedmem_of_table; i < &__rmem_of_table_sentinel; i++) {
	reservedmem_of_init_fn initfn = i->data;
	const char *compat = i->compatible;

	if (!of_flat_dt_is_compatible(rmem->fdt_node, compat))
	continue;

	ret = initfn(rmem);
	if (ret == 0) {
	pr_info("initialized node %s, compatible id %s\n",
	rmem->name, compat);
	break;
	}
	}
	return ret;
	}

	static int __init __rmem_cmp(const void a, const void b)
	{
	const struct reserved_mem ra = a, rb = b;

	if (ra->base < rb->base)
	return -1;

	if (ra->base > rb->base)
	return 1;

	/*
	* Put the dynamic allocations (address == 0, size == 0) before static
	* allocations at address 0x0 so that overlap detection works
	* correctly.
	*/
	if (ra->size < rb->size)
	return -1;
	if (ra->size > rb->size)
	return 1;

	return 0;
	}

	static void __init __rmem_check_for_overlap(void)
	{
	int i;

	if (reserved_mem_count < 2)
	return;

	sort(reserved_mem, reserved_mem_count, sizeof(reserved_mem[0]),
	__rmem_cmp, NULL);
	for (i = 0; i < reserved_mem_count - 1; i++) {
	struct reserved_mem this, next;

	this = &reserved_mem[i];
	next = &reserved_mem[i + 1];

	if (this->base + this->size > next->base) {
	phys_addr_t this_end, next_end;

	this_end = this->base + this->size;
	next_end = next->base + next->size;
	pr_err("OVERLAP DETECTED!\n%s (%pa--%pa) overlaps with %s (%pa--%pa)\n",
	this->name, &this->base, &this_end,
	next->name, &next->base, &next_end);
	}
	}
	}

	/**
	* fdt_init_reserved_mem() - allocate and init all saved reserved memory regions
	*/
	void __init fdt_init_reserved_mem(void)
	{
	int i;

	/* check for overlapping reserved regions */
	__rmem_check_for_overlap();

	for (i = 0; i < reserved_mem_count; i++) {
	struct reserved_mem *rmem = &reserved_mem[i];
	unsigned long node = rmem->fdt_node;
	int len;
	const __be32 *prop;
	int err = 0;
	bool nomap;

	nomap = of_get_flat_dt_prop(node, "no-map", NULL) != NULL;
	prop = of_get_flat_dt_prop(node, "phandle", &len);
	if (!prop)
	prop = of_get_flat_dt_prop(node, "linux,phandle", &len);
	if (prop)
	rmem->phandle = of_read_number(prop, len/4);

	if (rmem->size == 0)
	err = __reserved_mem_alloc_size(node, rmem->name,
	&rmem->base, &rmem->size);
	if (err == 0) {
	err = __reserved_mem_init_node(rmem);
	if (err != 0 && err != -ENOENT) {
	pr_info("node %s compatible matching fail\n",
	rmem->name);
	if (nomap)
	memblock_clear_nomap(rmem->base, rmem->size);
	else
	memblock_phys_free(rmem->base,
	rmem->size);
	} else {
	phys_addr_t end = rmem->base + rmem->size - 1;
	bool reusable =
	(of_get_flat_dt_prop(node, "reusable", NULL)) != NULL;

	pr_info("%pa..%pa ( %lu KB ) %s %s %s\n",
	&rmem->base, &end, (unsigned long)(rmem->size / SZ_1K),
	nomap ? "nomap" : "map",
	reusable ? "reusable" : "non-reusable",
	rmem->name ? rmem->name : "unknown");
	}
	}
	}
	}

	static inline struct reserved_mem __find_rmem(struct device_node node)
	{
	unsigned int i;

	if (!node->phandle)
	return NULL;

	for (i = 0; i < reserved_mem_count; i++)
	if (reserved_mem[i].phandle == node->phandle)
	return &reserved_mem[i];
	return NULL;
	}

	struct rmem_assigned_device {
	struct device *dev;
	struct reserved_mem *rmem;
	struct list_head list;
	};

	static LIST_HEAD(of_rmem_assigned_device_list);
	static DEFINE_MUTEX(of_rmem_assigned_device_mutex);

	/**
	* of_reserved_mem_device_init_by_idx() - assign reserved memory region to
	* given device
	* @dev: Pointer to the device to configure
	* @np: Pointer to the device_node with 'reserved-memory' property
	* @idx: Index of selected region
	*
	* This function assigns respective DMA-mapping operations based on reserved
	* memory region specified by 'memory-region' property in @np node to the @dev
	* device. When driver needs to use more than one reserved memory region, it
	* should allocate child devices and initialize regions by name for each of
	* child device.
	*
	* Returns error code or zero on success.
	*/
	int of_reserved_mem_device_init_by_idx(struct device *dev,
	struct device_node *np, int idx)
	{
	struct rmem_assigned_device *rd;
	struct device_node *target;
	struct reserved_mem *rmem;
	int ret;

	if (!np \|\| !dev)
	return -EINVAL;

	target = of_parse_phandle(np, "memory-region", idx);
	if (!target)
	return -ENODEV;

	if (!of_device_is_available(target)) {
	of_node_put(target);
	return 0;
	}

	rmem = __find_rmem(target);
	of_node_put(target);

	if (!rmem \|\| !rmem->ops \|\| !rmem->ops->device_init)
	return -EINVAL;

	rd = kmalloc(sizeof(struct rmem_assigned_device), GFP_KERNEL);
	if (!rd)
	return -ENOMEM;

	ret = rmem->ops->device_init(rmem, dev);
	if (ret == 0) {
	rd->dev = dev;
	rd->rmem = rmem;

	mutex_lock(&of_rmem_assigned_device_mutex);
	list_add(&rd->list, &of_rmem_assigned_device_list);
	mutex_unlock(&of_rmem_assigned_device_mutex);

	dev_info(dev, "assigned reserved memory node %s\n", rmem->name);
	} else {
	kfree(rd);
	}

	return ret;
	}
	EXPORT_SYMBOL_GPL(of_reserved_mem_device_init_by_idx);

	/**
	* of_reserved_mem_device_init_by_name() - assign named reserved memory region
	* to given device
	* @dev: pointer to the device to configure
	* @np: pointer to the device node with 'memory-region' property
	* @name: name of the selected memory region
	*
	* Returns: 0 on success or a negative error-code on failure.
	*/
	int of_reserved_mem_device_init_by_name(struct device *dev,
	struct device_node *np,
	const char *name)
	{
	int idx = of_property_match_string(np, "memory-region-names", name);

	return of_reserved_mem_device_init_by_idx(dev, np, idx);
	}
	EXPORT_SYMBOL_GPL(of_reserved_mem_device_init_by_name);

	/**
	* of_reserved_mem_device_release() - release reserved memory device structures
	* @dev: Pointer to the device to deconfigure
	*
	* This function releases structures allocated for memory region handling for
	* the given device.
	*/
	void of_reserved_mem_device_release(struct device *dev)
	{
	struct rmem_assigned_device rd, tmp;
	LIST_HEAD(release_list);

	mutex_lock(&of_rmem_assigned_device_mutex);
	list_for_each_entry_safe(rd, tmp, &of_rmem_assigned_device_list, list) {
	if (rd->dev == dev)
	list_move_tail(&rd->list, &release_list);
	}
	mutex_unlock(&of_rmem_assigned_device_mutex);

	list_for_each_entry_safe(rd, tmp, &release_list, list) {
	if (rd->rmem && rd->rmem->ops && rd->rmem->ops->device_release)
	rd->rmem->ops->device_release(rd->rmem, dev);

	kfree(rd);
	}
	}
	EXPORT_SYMBOL_GPL(of_reserved_mem_device_release);

	/**
	* of_reserved_mem_lookup() - acquire reserved_mem from a device node
	* @np: node pointer of the desired reserved-memory region
	*
	* This function allows drivers to acquire a reference to the reserved_mem
	* struct based on a device node handle.
	*
	* Returns a reserved_mem reference, or NULL on error.
	*/
	struct reserved_mem of_reserved_mem_lookup(struct device_node np)
	{
	const char *name;
	int i;

	if (!np->full_name)
	return NULL;

	name = kbasename(np->full_name);
	for (i = 0; i < reserved_mem_count; i++)
	if (!strcmp(reserved_mem[i].name, name))
	return &reserved_mem[i];

	return NULL;
	}
	EXPORT_SYMBOL_GPL(of_reserved_mem_lookup);