text: /*
   * 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>
  #include <pci.h>
  
  /*
   * A typedef for a physical address. Note that fdt data is always big
   * endian even on a litle endian machine.
   */
  typedef phys_addr_t fdt_addr_t;
  typedef phys_size_t fdt_size_t;
  #ifdef CONFIG_PHYS_64BIT
  #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
  #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;
  };
  
  #ifdef CONFIG_SPL_BUILD
  #define SPL_BUILD	1
  #else
  #define SPL_BUILD	0
  #endif
  
  /*
   * 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;
  };
  
  enum fdt_pci_space {
  	FDT_PCI_SPACE_CONFIG = 0,
  	FDT_PCI_SPACE_IO = 0x01000000,
  	FDT_PCI_SPACE_MEM32 = 0x02000000,
  	FDT_PCI_SPACE_MEM64 = 0x03000000,
  	FDT_PCI_SPACE_MEM32_PREF = 0x42000000,
  	FDT_PCI_SPACE_MEM64_PREF = 0x43000000,
  };
  
  #define FDT_PCI_ADDR_CELLS	3
  #define FDT_PCI_SIZE_CELLS	2
  #define FDT_PCI_REG_SIZE	\
  	((FDT_PCI_ADDR_CELLS + FDT_PCI_SIZE_CELLS) * sizeof(u32))
  
  /*
   * The Open Firmware spec defines PCI physical address as follows:
   *
   *          bits# 31 .... 24 23 .... 16 15 .... 08 07 .... 00
   *
   * phys.hi  cell:  npt000ss   bbbbbbbb   dddddfff   rrrrrrrr
   * phys.mid cell:  hhhhhhhh   hhhhhhhh   hhhhhhhh   hhhhhhhh
   * phys.lo  cell:  llllllll   llllllll   llllllll   llllllll
   *
   * where:
   *
   * n:        is 0 if the address is relocatable, 1 otherwise
   * p:        is 1 if addressable region is prefetchable, 0 otherwise
   * t:        is 1 if the address is aliased (for non-relocatable I/O) below 1MB
   *           (for Memory), or below 64KB (for relocatable I/O)
   * ss:       is the space code, denoting the address space
   * bbbbbbbb: is the 8-bit Bus Number
   * ddddd:    is the 5-bit Device Number
   * fff:      is the 3-bit Function Number
   * rrrrrrrr: is the 8-bit Register Number
   * hhhhhhhh: is a 32-bit unsigned number
   * llllllll: is a 32-bit unsigned number
   */
  struct fdt_pci_addr {
  	u32	phys_hi;
  	u32	phys_mid;
  	u32	phys_lo;
  };
  
  /**
   * 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_EMC,	/* Tegra20 memory controller */
  	COMPAT_NVIDIA_TEGRA20_EMC_TABLE, /* Tegra20 memory timing table */
  	COMPAT_NVIDIA_TEGRA20_NAND,	/* Tegra2 NAND controller */
  	COMPAT_NVIDIA_TEGRA20_PWM,	/* Tegra 2 PWM controller */
  	COMPAT_NVIDIA_TEGRA124_DC,	/* Tegra 124 Display controller */
  	COMPAT_NVIDIA_TEGRA124_SOR,	/* Tegra 124 Serial Output Resource */
  	COMPAT_NVIDIA_TEGRA124_PMC,	/* Tegra 124 power mgmt controller */
  	COMPAT_NVIDIA_TEGRA20_DC,	/* Tegra 2 Display controller */
  	COMPAT_NVIDIA_TEGRA210_SDMMC,	/* Tegra210 SDMMC controller */
  	COMPAT_NVIDIA_TEGRA124_SDMMC,	/* Tegra124 SDMMC controller */
  	COMPAT_NVIDIA_TEGRA30_SDMMC,	/* Tegra30 SDMMC controller */
  	COMPAT_NVIDIA_TEGRA20_SDMMC,	/* Tegra20 SDMMC controller */
  	COMPAT_NVIDIA_TEGRA124_XUSB_PADCTL,
  					/* Tegra124 XUSB pad controller */
  	COMPAT_NVIDIA_TEGRA210_XUSB_PADCTL,
  					/* Tegra210 XUSB pad 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_GOOGLE_CROS_EC_KEYB,	/* Google CROS_EC Keyboard */
  	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_SAMSUNG_EXYNOS5_I2C,	/* Exynos5 High Speed I2C Controller */
  	COMPAT_SAMSUNG_EXYNOS_SYSMMU,	/* Exynos sysmmu */
  	COMPAT_INTEL_MICROCODE,		/* Intel microcode update */
  	COMPAT_MEMORY_SPD,		/* Memory SPD information */
  	COMPAT_INTEL_PANTHERPOINT_AHCI,	/* Intel Pantherpoint AHCI */
  	COMPAT_INTEL_MODEL_206AX,	/* Intel Model 206AX CPU */
  	COMPAT_INTEL_GMA,		/* Intel Graphics Media Accelerator */
  	COMPAT_AMS_AS3722,		/* AMS AS3722 PMIC */
  	COMPAT_INTEL_ICH_SPI,		/* Intel ICH7/9 SPI controller */
  	COMPAT_INTEL_QRK_MRC,		/* Intel Quark MRC */
  	COMPAT_INTEL_X86_PINCTRL,	/* Intel ICH7/9 pin control */
  	COMPAT_SOCIONEXT_XHCI,		/* Socionext UniPhier xHCI */
  	COMPAT_INTEL_PCH,		/* Intel PCH */
  	COMPAT_ALTERA_SOCFPGA_DWMAC,	/* SoCFPGA Ethernet controller */
  	COMPAT_ALTERA_SOCFPGA_DWMMC,	/* SoCFPGA DWMMC controller */
  	COMPAT_ALTERA_SOCFPGA_DWC2USB,	/* SoCFPGA DWC2 USB controller */
  	COMPAT_INTEL_BAYTRAIL_FSP,	/* Intel Bay Trail FSP */
  	COMPAT_INTEL_BAYTRAIL_FSP_MDP,	/* Intel FSP memory-down params */
  	COMPAT_INTEL_IVYBRIDGE_FSP,	/* Intel Ivy Bridge FSP */
  
  	COMPAT_COUNT,
  };
  
  #define MAX_PHANDLE_ARGS 16
  struct fdtdec_phandle_args {
  	int node;
  	int args_count;
  	uint32_t args[MAX_PHANDLE_ARGS];
  };
  
  /**
   * fdtdec_parse_phandle_with_args() - Find a node pointed by phandle in a list
   *
   * This function is useful to parse lists of phandles and their arguments.
   *
   * Example:
   *
   * phandle1: node1 {
   *	#list-cells = <2>;
   * }
   *
   * phandle2: node2 {
   *	#list-cells = <1>;
   * }
   *
   * node3 {
   *	list = <&phandle1 1 2 &phandle2 3>;
   * }
   *
   * To get a device_node of the `node2' node you may call this:
   * fdtdec_parse_phandle_with_args(blob, node3, "list", "#list-cells", 0, 1,
   *				  &args);
   *
   * (This function is a modified version of __of_parse_phandle_with_args() from
   * Linux 3.18)
   *
   * @blob:	Pointer to device tree
   * @src_node:	Offset of device tree node containing a list
   * @list_name:	property name that contains a list
   * @cells_name:	property name that specifies the phandles' arguments count,
   *		or NULL to use @cells_count
   * @cells_count: Cell count to use if @cells_name is NULL
   * @index:	index of a phandle to parse out
   * @out_args:	optional pointer to output arguments structure (will be filled)
   * @return 0 on success (with @out_args filled out if not NULL), -ENOENT if
   *	@list_name does not exist, a phandle was not found, @cells_name
   *	could not be found, the arguments were truncated or there were too
   *	many arguments.
   *
   */
  int fdtdec_parse_phandle_with_args(const void *blob, int src_node,
  				   const char *list_name,
  				   const char *cells_name,
  				   int cell_count, int index,
  				   struct fdtdec_phandle_args *out_args);
  
  /**
   * 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 the parsed address, and
   * optionally the parsed size.
   *
   * This variant assumes a known and fixed number of cells are used to
   * represent the address and size.
   *
   * You probably don't want to use this function directly except to parse
   * non-standard properties, and never to parse the "reg" property. Instead,
   * use one of the "auto" variants below, which automatically honor the
   * #address-cells and #size-cells properties in the parent node.
   *
   * @param blob	FDT blob
   * @param node	node to examine
   * @param prop_name	name of property to find
   * @param index	which address to retrieve from a list of addresses. Often 0.
   * @param na	the number of cells used to represent an address
   * @param ns	the number of cells used to represent a size
   * @param sizep	a pointer to store the size into. Use NULL if not required
   * @return address, if found, or FDT_ADDR_T_NONE if not
   */
  fdt_addr_t fdtdec_get_addr_size_fixed(const void *blob, int node,
  		const char *prop_name, int index, int na, int ns,
  		fdt_size_t *sizep);
  
  /*
   * Look up an address property in a node and return the parsed address, and
   * optionally the parsed size.
   *
   * This variant automatically determines the number of cells used to represent
   * the address and size by parsing the provided parent node's #address-cells
   * and #size-cells properties.
   *
   * @param blob	FDT blob
   * @param parent	parent node of @node
   * @param node	node to examine
   * @param prop_name	name of property to find
   * @param index	which address to retrieve from a list of addresses. Often 0.
   * @param sizep	a pointer to store the size into. Use NULL if not required
   * @return address, if found, or FDT_ADDR_T_NONE if not
   */
  fdt_addr_t fdtdec_get_addr_size_auto_parent(const void *blob, int parent,
  		int node, const char *prop_name, int index, fdt_size_t *sizep);
  
  /*
   * Look up an address property in a node and return the parsed address, and
   * optionally the parsed size.
   *
   * This variant automatically determines the number of cells used to represent
   * the address and size by parsing the parent node's #address-cells
   * and #size-cells properties. The parent node is automatically found.
   *
   * The automatic parent lookup implemented by this function is slow.
   * Consequently, fdtdec_get_addr_size_auto_parent() should be used where
   * possible.
   *
   * @param blob	FDT blob
   * @param parent	parent node of @node
   * @param node	node to examine
   * @param prop_name	name of property to find
   * @param index	which address to retrieve from a list of addresses. Often 0.
   * @param sizep	a pointer to store the size into. Use NULL if not required
   * @return address, if found, or FDT_ADDR_T_NONE if not
   */
  fdt_addr_t fdtdec_get_addr_size_auto_noparent(const void *blob, int node,
  		const char *prop_name, int index, fdt_size_t *sizep);
  
  /*
   * Look up an address property in a node and return the parsed address.
   *
   * This variant hard-codes the number of cells used to represent the address
   * and size based on sizeof(fdt_addr_t) and sizeof(fdt_size_t). It also
   * always returns the first address value in the property (index 0).
   *
   * Use of this function is not recommended due to the hard-coding of cell
   * counts. There is no programmatic validation that these hard-coded values
   * actually match the device tree content in any way at all. This assumption
   * can be satisfied by manually ensuring CONFIG_PHYS_64BIT is appropriately
   * set in the U-Boot build and exercising strict control over DT content to
   * ensure use of matching #address-cells/#size-cells properties. However, this
   * approach is error-prone; those familiar with DT will not expect the
   * assumption to exist, and could easily invalidate it. If the assumption is
   * invalidated, this function will not report the issue, and debugging will
   * be required. Instead, use fdtdec_get_addr_size_auto_parent().
   *
   * @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 the parsed address, and
   * optionally the parsed size.
   *
   * This variant hard-codes the number of cells used to represent the address
   * and size based on sizeof(fdt_addr_t) and sizeof(fdt_size_t). It also
   * always returns the first address value in the property (index 0).
   *
   * Use of this function is not recommended due to the hard-coding of cell
   * counts. There is no programmatic validation that these hard-coded values
   * actually match the device tree content in any way at all. This assumption
   * can be satisfied by manually ensuring CONFIG_PHYS_64BIT is appropriately
   * set in the U-Boot build and exercising strict control over DT content to
   * ensure use of matching #address-cells/#size-cells properties. However, this
   * approach is error-prone; those familiar with DT will not expect the
   * assumption to exist, and could easily invalidate it. If the assumption is
   * invalidated, this function will not report the issue, and debugging will
   * be required. Instead, use fdtdec_get_addr_size_auto_parent().
   *
   * @param blob	FDT blob
   * @param node	node to examine
   * @param prop_name	name of property to find
   * @param sizep	a pointer to store the size into. Use NULL if not required
   * @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 at an address property in a node and return the pci address which
   * corresponds to the given type in the form of fdt_pci_addr.
   * The property must hold one fdt_pci_addr with a lengh.
   *
   * @param blob		FDT blob
   * @param node		node to examine
   * @param type		pci address type (FDT_PCI_SPACE_xxx)
   * @param prop_name	name of property to find
   * @param addr		returns pci address in the form of fdt_pci_addr
   * @return 0 if ok, -ENOENT if the property did not exist, -EINVAL if the
   *		format of the property was invalid, -ENXIO if the requested
   *		address type was not found
   */
  int fdtdec_get_pci_addr(const void *blob, int node, enum fdt_pci_space type,
  		const char *prop_name, struct fdt_pci_addr *addr);
  
  /**
   * Look at the compatible property of a device node that represents a PCI
   * device and extract pci vendor id and device id from it.
   *
   * @param blob		FDT blob
   * @param node		node to examine
   * @param vendor	vendor id of the pci device
   * @param device	device id of the pci device
   * @return 0 if ok, negative on error
   */
  int fdtdec_get_pci_vendev(const void *blob, int node,
  		u16 *vendor, u16 *device);
  
  /**
   * Look at the pci address of a device node that represents a PCI device
   * and return base address of the pci device's registers.
   *
   * @param dev		device to examine
   * @param addr		pci address in the form of fdt_pci_addr
   * @param bar		returns base address of the pci device's registers
   * @return 0 if ok, negative on error
   */
  int fdtdec_get_pci_bar32(struct udevice *dev, struct fdt_pci_addr *addr,
  			 u32 *bar);
  
  /**
   * 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);
  
  /**
   * Unsigned version of fdtdec_get_int. 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 unsigned integer value, if found, or default_val if not
   */
  unsigned int fdtdec_get_uint(const void *blob, int node, const char *prop_name,
  			unsigned int default_val);
  
  /**
   * Get a variable-sized number from a property
   *
   * This reads a number from one or more cells.
   *
   * @param ptr	Pointer to property
   * @param cells	Number of cells containing the number
   * @return the value in the cells
   */
  u64 fdtdec_get_number(const fdt32_t *ptr, unsigned int cells);
  
  /**
   * 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 a property from the /chosen node
   *
   * @param blob		Device tree blob (if NULL, then NULL is returned)
   * @param name		Property name to look up
   * @return Value of property, or NULL if it does not exist
   */
  const char *fdtdec_get_chosen_prop(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 its contents in an integer
   * array of given length. The property must exist but may have less data that
   * expected (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 number of array elements if ok, or -FDT_ERR_NOTFOUND if the
   *		property is not found
   */
  int fdtdec_get_int_array_count(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);
  
  /*
   * Count child nodes of one parent node.
   *
   * @param blob	FDT blob
   * @param node	parent node
   * @return number of child node; 0 if there is not child node
   */
  int fdtdec_get_child_count(const void *blob, int node);
  
  /**
   * 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 basep		Returns base address of region
   * @param size		Returns size of region
   * @return 0 if ok, -1 on error (property not found)
   */
  int fdtdec_decode_region(const void *blob, int node, const char *prop_name,
  			 fdt_addr_t *basep, fdt_size_t *sizep);
  
  enum fmap_compress_t {
  	FMAP_COMPRESS_NONE,
  	FMAP_COMPRESS_LZO,
  };
  
  enum fmap_hash_t {
  	FMAP_HASH_NONE,
  	FMAP_HASH_SHA1,
  	FMAP_HASH_SHA256,
  };
  
  /* A flash map entry, containing an offset and length */
  struct fmap_entry {
  	uint32_t offset;
  	uint32_t length;
  	uint32_t used;			/* Number of bytes used in region */
  	enum fmap_compress_t compress_algo;	/* Compression type */
  	enum fmap_hash_t hash_algo;		/* Hash algorithm */
  	const uint8_t *hash;			/* Hash value */
  	int hash_size;				/* Hash size */
  };
  
  /**
   * 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);
  
  /**
   * Decode a named region within a memory bank of a given type.
   *
   * This function handles selection of a memory region. The region is
   * specified as an offset/size within a particular type of memory.
   *
   * The properties used are:
   *
   *	<mem_type>-memory<suffix> for the name of the memory bank
   *	<mem_type>-offset<suffix> for the offset in that bank
   *
   * The property value must have an offset and a size. The function checks
   * that the region is entirely within the memory bank.5
   *
   * @param blob		FDT blob
   * @param node		Node containing the properties (-1 for /config)
   * @param mem_type	Type of memory to use, which is a name, such as
   *			"u-boot" or "kernel".
   * @param suffix	String to append to the memory/offset
   *			property names
   * @param basep		Returns base of region
   * @param sizep		Returns size of region
   * @return 0 if OK, -ive on error
   */
  int fdtdec_decode_memory_region(const void *blob, int node,
  				const char *mem_type, const char *suffix,
  				fdt_addr_t *basep, fdt_size_t *sizep);
  
  /* Display timings from linux include/video/display_timing.h */
  enum display_flags {
  	DISPLAY_FLAGS_HSYNC_LOW		= 1 << 0,
  	DISPLAY_FLAGS_HSYNC_HIGH	= 1 << 1,
  	DISPLAY_FLAGS_VSYNC_LOW		= 1 << 2,
  	DISPLAY_FLAGS_VSYNC_HIGH	= 1 << 3,
  
  	/* data enable flag */
  	DISPLAY_FLAGS_DE_LOW		= 1 << 4,
  	DISPLAY_FLAGS_DE_HIGH		= 1 << 5,
  	/* drive data on pos. edge */
  	DISPLAY_FLAGS_PIXDATA_POSEDGE	= 1 << 6,
  	/* drive data on neg. edge */
  	DISPLAY_FLAGS_PIXDATA_NEGEDGE	= 1 << 7,
  	DISPLAY_FLAGS_INTERLACED	= 1 << 8,
  	DISPLAY_FLAGS_DOUBLESCAN	= 1 << 9,
  	DISPLAY_FLAGS_DOUBLECLK		= 1 << 10,
  };
  
  /*
   * A single signal can be specified via a range of minimal and maximal values
   * with a typical value, that lies somewhere inbetween.
   */
  struct timing_entry {
  	u32 min;
  	u32 typ;
  	u32 max;
  };
  
  /*
   * Single "mode" entry. This describes one set of signal timings a display can
   * have in one setting. This struct can later be converted to struct videomode
   * (see include/video/videomode.h). As each timing_entry can be defined as a
   * range, one struct display_timing may become multiple struct videomodes.
   *
   * Example: hsync active high, vsync active low
   *
   *				    Active Video
   * Video  ______________________XXXXXXXXXXXXXXXXXXXXXX_____________________
   *	  |<- sync ->|<- back ->|<----- active ----->|<- front ->|<- sync..
   *	  |	     |	 porch  |		     |	 porch	 |
   *
   * HSync _|¯¯¯¯¯¯¯¯¯¯|___________________________________________|¯¯¯¯¯¯¯¯¯
   *
   * VSync ¯|__________|¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯|_________
   */
  struct display_timing {
  	struct timing_entry pixelclock;
  
  	struct timing_entry hactive;		/* hor. active video */
  	struct timing_entry hfront_porch;	/* hor. front porch */
  	struct timing_entry hback_porch;	/* hor. back porch */
  	struct timing_entry hsync_len;		/* hor. sync len */
  
  	struct timing_entry vactive;		/* ver. active video */
  	struct timing_entry vfront_porch;	/* ver. front porch */
  	struct timing_entry vback_porch;	/* ver. back porch */
  	struct timing_entry vsync_len;		/* ver. sync len */
  
  	enum display_flags flags;		/* display flags */
  };
  
  /**
   * fdtdec_decode_display_timing() - decode display timings
   *
   * Decode display timings from the supplied 'display-timings' node.
   * See doc/device-tree-bindings/video/display-timing.txt for binding
   * information.
   *
   * @param blob		FDT blob
   * @param node		'display-timing' node containing the timing subnodes
   * @param index		Index number to read (0=first timing subnode)
   * @param config	Place to put timings
   * @return 0 if OK, -FDT_ERR_NOTFOUND if not found
   */
  int fdtdec_decode_display_timing(const void *blob, int node, int index,
  				 struct display_timing *config);
  /**
   * Set up the device tree ready for use
   */
  int fdtdec_setup(void);
  
  #endif
  