path: root/include/fdtdec.h

/*
 * Copyright (c) 2011 The Chromium OS Authors.
 * SPDX-License-Identifier:	GPL-2.0+
 */

#ifndef __fdtdec_h
#define __fdtdec_h

/*
 * This file contains convenience functions for decoding useful and
 * enlightening information from FDTs. It is intended to be used by device
 * drivers and board-specific code within U-Boot. It aims to reduce the
 * amount of FDT munging required within U-Boot itself, so that driver code
 * changes to support FDT are minimized.
 */

#include <libfdt.h>

/*
 * A typedef for a physical address. Note that fdt data is always big
 * endian even on a litle endian machine.
 */
#ifdef CONFIG_PHYS_64BIT
typedef u64 fdt_addr_t;
typedef u64 fdt_size_t;
#define FDT_ADDR_T_NONE (-1ULL)
#define fdt_addr_to_cpu(reg) be64_to_cpu(reg)
#define fdt_size_to_cpu(reg) be64_to_cpu(reg)
#else
typedef u32 fdt_addr_t;
typedef u32 fdt_size_t;
#define FDT_ADDR_T_NONE (-1U)
#define fdt_addr_to_cpu(reg) be32_to_cpu(reg)
#define fdt_size_to_cpu(reg) be32_to_cpu(reg)
#endif

/* Information obtained about memory from the FDT */
struct fdt_memory {
	fdt_addr_t start;
	fdt_addr_t end;
};

/*
 * Information about a resource. start is the first address of the resource
 * and end is the last address (inclusive). The length of the resource will
 * be equal to: end - start + 1.
 */
struct fdt_resource {
	fdt_addr_t start;
	fdt_addr_t end;
};

/**
 * Compute the size of a resource.
 *
 * @param res	the resource to operate on
 * @return the size of the resource
 */
static inline fdt_size_t fdt_resource_size(const struct fdt_resource *res)
{
	return res->end - res->start + 1;
}

/**
 * Compat types that we know about and for which we might have drivers.
 * Each is named COMPAT_<dir>_<filename> where <dir> is the directory
 * within drivers.
 */
enum fdt_compat_id {
	COMPAT_UNKNOWN,
	COMPAT_NVIDIA_TEGRA20_USB,	/* Tegra20 USB port */
	COMPAT_NVIDIA_TEGRA30_USB,	/* Tegra30 USB port */
	COMPAT_NVIDIA_TEGRA114_USB,	/* Tegra114 USB port */
	COMPAT_NVIDIA_TEGRA114_I2C,	/* Tegra114 I2C w/single clock source */
	COMPAT_NVIDIA_TEGRA20_I2C,	/* Tegra20 i2c */
	COMPAT_NVIDIA_TEGRA20_DVC,	/* Tegra20 dvc (really just i2c) */
	COMPAT_NVIDIA_TEGRA20_EMC,	/* Tegra20 memory controller */
	COMPAT_NVIDIA_TEGRA20_EMC_TABLE, /* Tegra20 memory timing table */
	COMPAT_NVIDIA_TEGRA20_KBC,	/* Tegra20 Keyboard */
	COMPAT_NVIDIA_TEGRA20_NAND,	/* Tegra2 NAND controller */
	COMPAT_NVIDIA_TEGRA20_PWM,	/* Tegra 2 PWM controller */
	COMPAT_NVIDIA_TEGRA20_DC,	/* Tegra 2 Display controller */
	COMPAT_NVIDIA_TEGRA124_SDMMC,	/* Tegra124 SDMMC controller */
	COMPAT_NVIDIA_TEGRA30_SDMMC,	/* Tegra30 SDMMC controller */
	COMPAT_NVIDIA_TEGRA20_SDMMC,	/* Tegra20 SDMMC controller */
	COMPAT_NVIDIA_TEGRA20_SFLASH,	/* Tegra 2 SPI flash controller */
	COMPAT_NVIDIA_TEGRA20_SLINK,	/* Tegra 2 SPI SLINK controller */
	COMPAT_NVIDIA_TEGRA114_SPI,	/* Tegra 114 SPI controller */
	COMPAT_SMSC_LAN9215,		/* SMSC 10/100 Ethernet LAN9215 */
	COMPAT_SAMSUNG_EXYNOS5_SROMC,	/* Exynos5 SROMC */
	COMPAT_SAMSUNG_S3C2440_I2C,	/* Exynos I2C Controller */
	COMPAT_SAMSUNG_EXYNOS5_SOUND,	/* Exynos Sound */
	COMPAT_WOLFSON_WM8994_CODEC,	/* Wolfson WM8994 Sound Codec */
	COMPAT_SAMSUNG_EXYNOS_SPI,	/* Exynos SPI */
	COMPAT_GOOGLE_CROS_EC,		/* Google CROS_EC Protocol */
	COMPAT_GOOGLE_CROS_EC_KEYB,	/* Google CROS_EC Keyboard */
	COMPAT_SAMSUNG_EXYNOS_EHCI,	/* Exynos EHCI controller */
	COMPAT_SAMSUNG_EXYNOS5_XHCI,	/* Exynos5 XHCI controller */
	COMPAT_SAMSUNG_EXYNOS_USB_PHY,	/* Exynos phy controller for usb2.0 */
	COMPAT_SAMSUNG_EXYNOS5_USB3_PHY,/* Exynos phy controller for usb3.0 */
	COMPAT_SAMSUNG_EXYNOS_TMU,	/* Exynos TMU */
	COMPAT_SAMSUNG_EXYNOS_FIMD,	/* Exynos Display controller */
	COMPAT_SAMSUNG_EXYNOS_MIPI_DSI,	/* Exynos mipi dsi */
	COMPAT_SAMSUNG_EXYNOS5_DP,	/* Exynos Display port controller */
	COMPAT_SAMSUNG_EXYNOS_DWMMC,	/* Exynos DWMMC controller */
	COMPAT_SAMSUNG_EXYNOS_MMC,	/* Exynos MMC controller */
	COMPAT_SAMSUNG_EXYNOS_SERIAL,	/* Exynos UART */
	COMPAT_MAXIM_MAX77686_PMIC,	/* MAX77686 PMIC */
	COMPAT_GENERIC_SPI_FLASH,	/* Generic SPI Flash chip */
	COMPAT_MAXIM_98095_CODEC,	/* MAX98095 Codec */
	COMPAT_INFINEON_SLB9635_TPM,	/* Infineon SLB9635 TPM */
	COMPAT_INFINEON_SLB9645_TPM,	/* Infineon SLB9645 TPM */
	COMPAT_SAMSUNG_EXYNOS5_I2C,	/* Exynos5 High Speed I2C Controller */
	COMPAT_SANDBOX_HOST_EMULATION,	/* Sandbox emulation of a function */
	COMPAT_SANDBOX_LCD_SDL,		/* Sandbox LCD emulation with SDL */
	COMPAT_TI_TPS65090,		/* Texas Instrument TPS65090 */
	COMPAT_NXP_PTN3460,		/* NXP PTN3460 DP/LVDS bridge */
	COMPAT_SAMSUNG_EXYNOS_SYSMMU,	/* Exynos sysmmu */
	COMPAT_PARADE_PS8625,		/* Parade PS8622 EDP->LVDS bridge */

	COMPAT_COUNT,
};

/* GPIOs are numbered from 0 */
enum {
	FDT_GPIO_NONE = -1U,	/* an invalid GPIO used to end our list */

	FDT_GPIO_ACTIVE_LOW = 1 << 0,	/* input is active low (else high) */
};

/* This is the state of a GPIO pin as defined by the fdt */
struct fdt_gpio_state {
	const char *name;	/* name of the fdt property defining this */
	uint gpio;		/* GPIO number, or FDT_GPIO_NONE if none */
	u8 flags;		/* FDT_GPIO_... flags */
};

/* This tells us whether a fdt_gpio_state record is valid or not */
#define fdt_gpio_isvalid(x) ((x)->gpio != FDT_GPIO_NONE)

/**
 * Read the GPIO taking into account the polarity of the pin.
 *
 * @param gpio		pointer to the decoded gpio
 * @return value of the gpio if successful, < 0 if unsuccessful
 */
int fdtdec_get_gpio(struct fdt_gpio_state *gpio);

/**
 * Write the GPIO taking into account the polarity of the pin.
 *
 * @param gpio		pointer to the decoded gpio
 * @return 0 if successful
 */
int fdtdec_set_gpio(struct fdt_gpio_state *gpio, int val);

/**
 * Find the next numbered alias for a peripheral. This is used to enumerate
 * all the peripherals of a certain type.
 *
 * Do the first call with *upto = 0. Assuming /aliases/<name>0 exists then
 * this function will return a pointer to the node the alias points to, and
 * then update *upto to 1. Next time you call this function, the next node
 * will be returned.
 *
 * All nodes returned will match the compatible ID, as it is assumed that
 * all peripherals use the same driver.
 *
 * @param blob		FDT blob to use
 * @param name		Root name of alias to search for
 * @param id		Compatible ID to look for
 * @return offset of next compatible node, or -FDT_ERR_NOTFOUND if no more
 */
int fdtdec_next_alias(const void *blob, const char *name,
		enum fdt_compat_id id, int *upto);

/**
 * Find the compatible ID for a given node.
 *
 * Generally each node has at least one compatible string attached to it.
 * This function looks through our list of known compatible strings and
 * returns the corresponding ID which matches the compatible string.
 *
 * @param blob		FDT blob to use
 * @param node		Node containing compatible string to find
 * @return compatible ID, or COMPAT_UNKNOWN if we cannot find a match
 */
enum fdt_compat_id fdtdec_lookup(const void *blob, int node);

/**
 * Find the next compatible node for a peripheral.
 *
 * Do the first call with node = 0. This function will return a pointer to
 * the next compatible node. Next time you call this function, pass the
 * value returned, and the next node will be provided.
 *
 * @param blob		FDT blob to use
 * @param node		Start node for search
 * @param id		Compatible ID to look for (enum fdt_compat_id)
 * @return offset of next compatible node, or -FDT_ERR_NOTFOUND if no more
 */
int fdtdec_next_compatible(const void *blob, int node,
		enum fdt_compat_id id);

/**
 * Find the next compatible subnode for a peripheral.
 *
 * Do the first call with node set to the parent and depth = 0. This
 * function will return the offset of the next compatible node. Next time
 * you call this function, pass the node value returned last time, with
 * depth unchanged, and the next node will be provided.
 *
 * @param blob		FDT blob to use
 * @param node		Start node for search
 * @param id		Compatible ID to look for (enum fdt_compat_id)
 * @param depthp	Current depth (set to 0 before first call)
 * @return offset of next compatible node, or -FDT_ERR_NOTFOUND if no more
 */
int fdtdec_next_compatible_subnode(const void *blob, int node,
		enum fdt_compat_id id, int *depthp);

/**
 * Look up an address property in a node and return it as an address.
 * The property must hold either one address with no trailing data or
 * one address with a length. This is only tested on 32-bit machines.
 *
 * @param blob	FDT blob
 * @param node	node to examine
 * @param prop_name	name of property to find
 * @return address, if found, or FDT_ADDR_T_NONE if not
 */
fdt_addr_t fdtdec_get_addr(const void *blob, int node,
		const char *prop_name);

/**
 * Look up an address property in a node and return it as an address.
 * The property must hold one address with a length. This is only tested
 * on 32-bit machines.
 *
 * @param blob	FDT blob
 * @param node	node to examine
 * @param prop_name	name of property to find
 * @return address, if found, or FDT_ADDR_T_NONE if not
 */
fdt_addr_t fdtdec_get_addr_size(const void *blob, int node,
		const char *prop_name, fdt_size_t *sizep);

/**
 * Look up a 32-bit integer property in a node and return it. The property
 * must have at least 4 bytes of data. The value of the first cell is
 * returned.
 *
 * @param blob	FDT blob
 * @param node	node to examine
 * @param prop_name	name of property to find
 * @param default_val	default value to return if the property is not found
 * @return integer value, if found, or default_val if not
 */
s32 fdtdec_get_int(const void *blob, int node, const char *prop_name,
		s32 default_val);

/**
 * Look up a 64-bit integer property in a node and return it. The property
 * must have at least 8 bytes of data (2 cells). The first two cells are
 * concatenated to form a 8 bytes value, where the first cell is top half and
 * the second cell is bottom half.
 *
 * @param blob	FDT blob
 * @param node	node to examine
 * @param prop_name	name of property to find
 * @param default_val	default value to return if the property is not found
 * @return integer value, if found, or default_val if not
 */
uint64_t fdtdec_get_uint64(const void *blob, int node, const char *prop_name,
		uint64_t default_val);

/**
 * Checks whether a node is enabled.
 * This looks for a 'status' property. If this exists, then returns 1 if
 * the status is 'ok' and 0 otherwise. If there is no status property,
 * it returns 1 on the assumption that anything mentioned should be enabled
 * by default.
 *
 * @param blob	FDT blob
 * @param node	node to examine
 * @return integer value 0 (not enabled) or 1 (enabled)
 */
int fdtdec_get_is_enabled(const void *blob, int node);

/**
 * Make sure we have a valid fdt available to control U-Boot.
 *
 * If not, a message is printed to the console if the console is ready.
 *
 * @return 0 if all ok, -1 if not
 */
int fdtdec_prepare_fdt(void);

/**
 * Checks that we have a valid fdt available to control U-Boot.

 * However, if not then for the moment nothing is done, since this function
 * is called too early to panic().
 *
 * @returns 0
 */
int fdtdec_check_fdt(void);

/**
 * Find the nodes for a peripheral and return a list of them in the correct
 * order. This is used to enumerate all the peripherals of a certain type.
 *
 * To use this, optionally set up a /aliases node with alias properties for
 * a peripheral. For example, for usb you could have:
 *
 * aliases {
 *		usb0 = "/ehci@c5008000";
 *		usb1 = "/ehci@c5000000";
 * };
 *
 * Pass "usb" as the name to this function and will return a list of two
 * nodes offsets: /ehci@c5008000 and ehci@c5000000.
 *
 * All nodes returned will match the compatible ID, as it is assumed that
 * all peripherals use the same driver.
 *
 * If no alias node is found, then the node list will be returned in the
 * order found in the fdt. If the aliases mention a node which doesn't
 * exist, then this will be ignored. If nodes are found with no aliases,
 * they will be added in any order.
 *
 * If there is a gap in the aliases, then this function return a 0 node at
 * that position. The return value will also count these gaps.
 *
 * This function checks node properties and will not return nodes which are
 * marked disabled (status = "disabled").
 *
 * @param blob		FDT blob to use
 * @param name		Root name of alias to search for
 * @param id		Compatible ID to look for
 * @param node_list	Place to put list of found nodes
 * @param maxcount	Maximum number of nodes to find
 * @return number of nodes found on success, FTD_ERR_... on error
 */
int fdtdec_find_aliases_for_id(const void *blob, const char *name,
			enum fdt_compat_id id, int *node_list, int maxcount);

/*
 * This function is similar to fdtdec_find_aliases_for_id() except that it
 * adds to the node_list that is passed in. Any 0 elements are considered
 * available for allocation - others are considered already used and are
 * skipped.
 *
 * You can use this by calling fdtdec_find_aliases_for_id() with an
 * uninitialised array, then setting the elements that are returned to -1,
 * say, then calling this function, perhaps with a different compat id.
 * Any elements you get back that are >0 are new nodes added by the call
 * to this function.
 *
 * Note that if you have some nodes with aliases and some without, you are
 * sailing close to the wind. The call to fdtdec_find_aliases_for_id() with
 * one compat_id may fill in positions for which you have aliases defined
 * for another compat_id. When you later call *this* function with the second
 * compat_id, the alias positions may already be used. A debug warning may
 * be generated in this case, but it is safest to define aliases for all
 * nodes when you care about the ordering.
 */
int fdtdec_add_aliases_for_id(const void *blob, const char *name,
			enum fdt_compat_id id, int *node_list, int maxcount);

/**
 * Get the alias sequence number of a node
 *
 * This works out whether a node is pointed to by an alias, and if so, the
 * sequence number of that alias. Aliases are of the form <base><num> where
 * <num> is the sequence number. For example spi2 would be sequence number
 * 2.
 *
 * @param blob		Device tree blob (if NULL, then error is returned)
 * @param base		Base name for alias (before the underscore)
 * @param node		Node to look up
 * @param seqp		This is set to the sequence number if one is found,
 *			but otherwise the value is left alone
 * @return 0 if a sequence was found, -ve if not
 */
int fdtdec_get_alias_seq(const void *blob, const char *base, int node,
			 int *seqp);

/**
 * Get the offset of the given alias node
 *
 * This looks up an alias in /aliases then finds the offset of that node.
 *
 * @param blob		Device tree blob (if NULL, then error is returned)
 * @param name		Alias name, e.g. "console"
 * @return Node offset referred to by that alias, or -ve FDT_ERR_...
 */
int fdtdec_get_alias_node(const void *blob, const char *name);

/**
 * Get the offset of the given chosen node
 *
 * This looks up a property in /chosen containing the path to another node,
 * then finds the offset of that node.
 *
 * @param blob		Device tree blob (if NULL, then error is returned)
 * @param name		Property name, e.g. "stdout-path"
 * @return Node offset referred to by that chosen node, or -ve FDT_ERR_...
 */
int fdtdec_get_chosen_node(const void *blob, const char *name);

/*
 * Get the name for a compatible ID
 *
 * @param id		Compatible ID to look for
 * @return compatible string for that id
 */
const char *fdtdec_get_compatible(enum fdt_compat_id id);

/* Look up a phandle and follow it to its node. Then return the offset
 * of that node.
 *
 * @param blob		FDT blob
 * @param node		node to examine
 * @param prop_name	name of property to find
 * @return node offset if found, -ve error code on error
 */
int fdtdec_lookup_phandle(const void *blob, int node, const char *prop_name);

/**
 * Look up a property in a node and return its contents in an integer
 * array of given length. The property must have at least enough data for
 * the array (4*count bytes). It may have more, but this will be ignored.
 *
 * @param blob		FDT blob
 * @param node		node to examine
 * @param prop_name	name of property to find
 * @param array		array to fill with data
 * @param count		number of array elements
 * @return 0 if ok, or -FDT_ERR_NOTFOUND if the property is not found,
 *		or -FDT_ERR_BADLAYOUT if not enough data
 */
int fdtdec_get_int_array(const void *blob, int node, const char *prop_name,
		u32 *array, int count);

/**
 * Look up a property in a node and return a pointer to its contents as a
 * unsigned int array of given length. The property must have at least enough
 * data for the array ('count' cells). It may have more, but this will be
 * ignored. The data is not copied.
 *
 * Note that you must access elements of the array with fdt32_to_cpu(),
 * since the elements will be big endian even on a little endian machine.
 *
 * @param blob		FDT blob
 * @param node		node to examine
 * @param prop_name	name of property to find
 * @param count		number of array elements
 * @return pointer to array if found, or NULL if the property is not
 *		found or there is not enough data
 */
const u32 *fdtdec_locate_array(const void *blob, int node,
			       const char *prop_name, int count);

/**
 * Look up a boolean property in a node and return it.
 *
 * A boolean properly is true if present in the device tree and false if not
 * present, regardless of its value.
 *
 * @param blob	FDT blob
 * @param node	node to examine
 * @param prop_name	name of property to find
 * @return 1 if the properly is present; 0 if it isn't present
 */
int fdtdec_get_bool(const void *blob, int node, const char *prop_name);

/**
 * Decode a single GPIOs from an FDT.
 *
 * If the property is not found, then the GPIO structure will still be
 * initialised, with gpio set to FDT_GPIO_NONE. This makes it easy to
 * provide optional GPIOs.
 *
 * @param blob		FDT blob to use
 * @param node		Node to look at
 * @param prop_name	Node property name
 * @param gpio		gpio elements to fill from FDT
 * @return 0 if ok, -FDT_ERR_NOTFOUND if the property is missing.
 */
int fdtdec_decode_gpio(const void *blob, int node, const char *prop_name,
		struct fdt_gpio_state *gpio);

/**
 * Decode a list of GPIOs from an FDT. This creates a list of GPIOs with no
 * terminating item.
 *
 * @param blob         FDT blob to use
 * @param node         Node to look at
 * @param prop_name    Node property name
 * @param gpio         Array of gpio elements to fill from FDT. This will be
 *                     untouched if either 0 or an error is returned
 * @param max_count    Maximum number of elements allowed
 * @return number of GPIOs read if ok, -FDT_ERR_BADLAYOUT if max_count would
 * be exceeded, or -FDT_ERR_NOTFOUND if the property is missing.
 */
int fdtdec_decode_gpios(const void *blob, int node, const char *prop_name,
		struct fdt_gpio_state *gpio, int max_count);

/**
 * Set up a GPIO pin according to the provided gpio information. At present this
 * just requests the GPIO.
 *
 * If the gpio is FDT_GPIO_NONE, no action is taken. This makes it easy to
 * deal with optional GPIOs.
 *
 * @param gpio		GPIO info to use for set up
 * @return 0 if all ok or gpio was FDT_GPIO_NONE; -1 on error
 */
int fdtdec_setup_gpio(struct fdt_gpio_state *gpio);

/**
 * Look in the FDT for a config item with the given name and return its value
 * as a 32-bit integer. The property must have at least 4 bytes of data. The
 * value of the first cell is returned.
 *
 * @param blob		FDT blob to use
 * @param prop_name	Node property name
 * @param default_val	default value to return if the property is not found
 * @return integer value, if found, or default_val if not
 */
int fdtdec_get_config_int(const void *blob, const char *prop_name,
		int default_val);

/**
 * Look in the FDT for a config item with the given name
 * and return whether it exists.
 *
 * @param blob		FDT blob
 * @param prop_name	property name to look up
 * @return 1, if it exists, or 0 if not
 */
int fdtdec_get_config_bool(const void *blob, const char *prop_name);

/**
 * Look in the FDT for a config item with the given name and return its value
 * as a string.
 *
 * @param blob          FDT blob
 * @param prop_name     property name to look up
 * @returns property string, NULL on error.
 */
char *fdtdec_get_config_string(const void *blob, const char *prop_name);

/*
 * Look up a property in a node and return its contents in a byte
 * array of given length. The property must have at least enough data for
 * the array (count bytes). It may have more, but this will be ignored.
 *
 * @param blob		FDT blob
 * @param node		node to examine
 * @param prop_name	name of property to find
 * @param array		array to fill with data
 * @param count		number of array elements
 * @return 0 if ok, or -FDT_ERR_MISSING if the property is not found,
 *		or -FDT_ERR_BADLAYOUT if not enough data
 */
int fdtdec_get_byte_array(const void *blob, int node, const char *prop_name,
		u8 *array, int count);

/**
 * Look up a property in a node and return a pointer to its contents as a
 * byte array of given length. The property must have at least enough data
 * for the array (count bytes). It may have more, but this will be ignored.
 * The data is not copied.
 *
 * @param blob		FDT blob
 * @param node		node to examine
 * @param prop_name	name of property to find
 * @param count		number of array elements
 * @return pointer to byte array if found, or NULL if the property is not
 *		found or there is not enough data
 */
const u8 *fdtdec_locate_byte_array(const void *blob, int node,
			     const char *prop_name, int count);

/**
 * Look up a property in a node which contains a memory region address and
 * size. Then return a pointer to this address.
 *
 * The property must hold one address with a length. This is only tested on
 * 32-bit machines.
 *
 * @param blob		FDT blob
 * @param node		node to examine
 * @param prop_name	name of property to find
 * @param ptrp		returns pointer to region, or NULL if no address
 * @param size		returns size of region
 * @return 0 if ok, -1 on error (propery not found)
 */
int fdtdec_decode_region(const void *blob, int node,
		const char *prop_name, void **ptrp, size_t *size);

/* A flash map entry, containing an offset and length */
struct fmap_entry {
	uint32_t offset;
	uint32_t length;
};

/**
 * Read a flash entry from the fdt
 *
 * @param blob		FDT blob
 * @param node		Offset of node to read
 * @param name		Name of node being read
 * @param entry		Place to put offset and size of this node
 * @return 0 if ok, -ve on error
 */
int fdtdec_read_fmap_entry(const void *blob, int node, const char *name,
			   struct fmap_entry *entry);

/**
 * Obtain an indexed resource from a device property.
 *
 * @param fdt		FDT blob
 * @param node		node to examine
 * @param property	name of the property to parse
 * @param index		index of the resource to retrieve
 * @param res		returns the resource
 * @return 0 if ok, negative on error
 */
int fdt_get_resource(const void *fdt, int node, const char *property,
		     unsigned int index, struct fdt_resource *res);

/**
 * Obtain a named resource from a device property.
 *
 * Look up the index of the name in a list of strings and return the resource
 * at that index.
 *
 * @param fdt		FDT blob
 * @param node		node to examine
 * @param property	name of the property to parse
 * @param prop_names	name of the property containing the list of names
 * @param name		the name of the entry to look up
 * @param res		returns the resource
 */
int fdt_get_named_resource(const void *fdt, int node, const char *property,
			   const char *prop_names, const char *name,
			   struct fdt_resource *res);

#endif