libfdt: Add max phandle retrieval function

[u-boot] / include / libfdt.h

#ifndef _LIBFDT_H
#define _LIBFDT_H
/*
 * libfdt - Flat Device Tree manipulation
 * Copyright (C) 2006 David Gibson, IBM Corporation.
 *
 * libfdt is dual licensed: you can use it either under the terms of
 * the GPL, or the BSD license, at your option.
 *
 *  a) This library is free software; you can redistribute it and/or
 *     modify it under the terms of the GNU General Public License as
 *     published by the Free Software Foundation; either version 2 of the
 *     License, or (at your option) any later version.
 *
 *     This library is distributed in the hope that it will be useful,
 *     but WITHOUT ANY WARRANTY; without even the implied warranty of
 *     MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 *     GNU General Public License for more details.
 *
 *     You should have received a copy of the GNU General Public
 *     License along with this library; if not, write to the Free
 *     Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston,
 *     MA 02110-1301 USA
 *
 * Alternatively,
 *
 *  b) Redistribution and use in source and binary forms, with or
 *     without modification, are permitted provided that the following
 *     conditions are met:
 *
 *     1. Redistributions of source code must retain the above
 *        copyright notice, this list of conditions and the following
 *        disclaimer.
 *     2. Redistributions in binary form must reproduce the above
 *        copyright notice, this list of conditions and the following
 *        disclaimer in the documentation and/or other materials
 *        provided with the distribution.
 *
 *     THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND
 *     CONTRIBUTORS "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES,
 *     INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
 *     MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
 *     DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR
 *     CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
 *     SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
 *     NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
 *     LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 *     HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
 *     CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR
 *     OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE,
 *     EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */

#include <libfdt_env.h>
#include <fdt.h>

#define FDT_FIRST_SUPPORTED_VERSION     0x10
#define FDT_LAST_SUPPORTED_VERSION      0x11

/* Error codes: informative error codes */
#define FDT_ERR_NOTFOUND        1
        /* FDT_ERR_NOTFOUND: The requested node or property does not exist */
#define FDT_ERR_EXISTS          2
        /* FDT_ERR_EXISTS: Attemped to create a node or property which
         * already exists */
#define FDT_ERR_NOSPACE         3
        /* FDT_ERR_NOSPACE: Operation needed to expand the device
         * tree, but its buffer did not have sufficient space to
         * contain the expanded tree. Use fdt_open_into() to move the
         * device tree to a buffer with more space. */

/* Error codes: codes for bad parameters */
#define FDT_ERR_BADOFFSET       4
        /* FDT_ERR_BADOFFSET: Function was passed a structure block
         * offset which is out-of-bounds, or which points to an
         * unsuitable part of the structure for the operation. */
#define FDT_ERR_BADPATH         5
        /* FDT_ERR_BADPATH: Function was passed a badly formatted path
         * (e.g. missing a leading / for a function which requires an
         * absolute path) */
#define FDT_ERR_BADPHANDLE      6
        /* FDT_ERR_BADPHANDLE: Function was passed an invalid phandle
         * value.  phandle values of 0 and -1 are not permitted. */
#define FDT_ERR_BADSTATE        7
        /* FDT_ERR_BADSTATE: Function was passed an incomplete device
         * tree created by the sequential-write functions, which is
         * not sufficiently complete for the requested operation. */

/* Error codes: codes for bad device tree blobs */
#define FDT_ERR_TRUNCATED       8
        /* FDT_ERR_TRUNCATED: Structure block of the given device tree
         * ends without an FDT_END tag. */
#define FDT_ERR_BADMAGIC        9
        /* FDT_ERR_BADMAGIC: Given "device tree" appears not to be a
         * device tree at all - it is missing the flattened device
         * tree magic number. */
#define FDT_ERR_BADVERSION      10
        /* FDT_ERR_BADVERSION: Given device tree has a version which
         * can't be handled by the requested operation.  For
         * read-write functions, this may mean that fdt_open_into() is
         * required to convert the tree to the expected version. */
#define FDT_ERR_BADSTRUCTURE    11
        /* FDT_ERR_BADSTRUCTURE: Given device tree has a corrupt
         * structure block or other serious error (e.g. misnested
         * nodes, or subnodes preceding properties). */
#define FDT_ERR_BADLAYOUT       12
        /* FDT_ERR_BADLAYOUT: For read-write functions, the given
         * device tree has it's sub-blocks in an order that the
         * function can't handle (memory reserve map, then structure,
         * then strings).  Use fdt_open_into() to reorganize the tree
         * into a form suitable for the read-write operations. */

/* "Can't happen" error indicating a bug in libfdt */
#define FDT_ERR_INTERNAL        13
        /* FDT_ERR_INTERNAL: libfdt has failed an internal assertion.
         * Should never be returned, if it is, it indicates a bug in
         * libfdt itself. */

/* Errors in device tree content */
#define FDT_ERR_BADNCELLS       14
        /* FDT_ERR_BADNCELLS: Device tree has a #address-cells, #size-cells
         * or similar property with a bad format or value */

#define FDT_ERR_TOODEEP         15
        /* FDT_ERR_TOODEEP: The depth of a node has exceeded the internal
         * libfdt limit. This can happen if you have more than
         * FDT_MAX_DEPTH nested nodes. */

#define FDT_ERR_MAX             15

/**********************************************************************/
/* Low-level functions (you probably don't need these)                */
/**********************************************************************/

const void *fdt_offset_ptr(const void *fdt, int offset, unsigned int checklen);
static inline void *fdt_offset_ptr_w(void *fdt, int offset, int checklen)
{
        return (void *)(uintptr_t)fdt_offset_ptr(fdt, offset, checklen);
}

uint32_t fdt_next_tag(const void *fdt, int offset, int *nextoffset);

/**********************************************************************/
/* Traversal functions                                                */
/**********************************************************************/

int fdt_next_node(const void *fdt, int offset, int *depth);

/**
 * fdt_first_subnode() - get offset of first direct subnode
 *
 * @fdt:        FDT blob
 * @offset:     Offset of node to check
 * @return offset of first subnode, or -FDT_ERR_NOTFOUND if there is none
 */
int fdt_first_subnode(const void *fdt, int offset);

/**
 * fdt_next_subnode() - get offset of next direct subnode
 *
 * After first calling fdt_first_subnode(), call this function repeatedly to
 * get direct subnodes of a parent node.
 *
 * @fdt:        FDT blob
 * @offset:     Offset of previous subnode
 * @return offset of next subnode, or -FDT_ERR_NOTFOUND if there are no more
 * subnodes
 */
int fdt_next_subnode(const void *fdt, int offset);

/**
 * fdt_for_each_subnode - iterate over all subnodes of a parent
 *
 * This is actually a wrapper around a for loop and would be used like so:
 *
 *      fdt_for_each_subnode(fdt, node, parent) {
 *              ...
 *              use node
 *              ...
 *      }
 *
 * Note that this is implemented as a macro and node is used as iterator in
 * the loop. It should therefore be a locally allocated variable. The parent
 * variable on the other hand is never modified, so it can be constant or
 * even a literal.
 *
 * @fdt:        FDT blob (const void *)
 * @node:       child node (int)
 * @parent:     parent node (int)
 */
#define fdt_for_each_subnode(fdt, node, parent)         \
        for (node = fdt_first_subnode(fdt, parent);     \
             node >= 0;                                 \
             node = fdt_next_subnode(fdt, node))

/**********************************************************************/
/* General functions                                                  */
/**********************************************************************/

#define fdt_get_header(fdt, field) \
        (fdt32_to_cpu(((const struct fdt_header *)(fdt))->field))
#define fdt_magic(fdt)                  (fdt_get_header(fdt, magic))
#define fdt_totalsize(fdt)              (fdt_get_header(fdt, totalsize))
#define fdt_off_dt_struct(fdt)          (fdt_get_header(fdt, off_dt_struct))
#define fdt_off_dt_strings(fdt)         (fdt_get_header(fdt, off_dt_strings))
#define fdt_off_mem_rsvmap(fdt)         (fdt_get_header(fdt, off_mem_rsvmap))
#define fdt_version(fdt)                (fdt_get_header(fdt, version))
#define fdt_last_comp_version(fdt)      (fdt_get_header(fdt, last_comp_version))
#define fdt_boot_cpuid_phys(fdt)        (fdt_get_header(fdt, boot_cpuid_phys))
#define fdt_size_dt_strings(fdt)        (fdt_get_header(fdt, size_dt_strings))
#define fdt_size_dt_struct(fdt)         (fdt_get_header(fdt, size_dt_struct))

#define __fdt_set_hdr(name) \
        static inline void fdt_set_##name(void *fdt, uint32_t val) \
        { \
                struct fdt_header *fdth = (struct fdt_header*)fdt; \
                fdth->name = cpu_to_fdt32(val); \
        }
__fdt_set_hdr(magic);
__fdt_set_hdr(totalsize);
__fdt_set_hdr(off_dt_struct);
__fdt_set_hdr(off_dt_strings);
__fdt_set_hdr(off_mem_rsvmap);
__fdt_set_hdr(version);
__fdt_set_hdr(last_comp_version);
__fdt_set_hdr(boot_cpuid_phys);
__fdt_set_hdr(size_dt_strings);
__fdt_set_hdr(size_dt_struct);
#undef __fdt_set_hdr

/**
 * fdt_check_header - sanity check a device tree or possible device tree
 * @fdt: pointer to data which might be a flattened device tree
 *
 * fdt_check_header() checks that the given buffer contains what
 * appears to be a flattened device tree with sane information in its
 * header.
 *
 * returns:
 *     0, if the buffer appears to contain a valid device tree
 *     -FDT_ERR_BADMAGIC,
 *     -FDT_ERR_BADVERSION,
 *     -FDT_ERR_BADSTATE, standard meanings, as above
 */
int fdt_check_header(const void *fdt);

/**
 * fdt_move - move a device tree around in memory
 * @fdt: pointer to the device tree to move
 * @buf: pointer to memory where the device is to be moved
 * @bufsize: size of the memory space at buf
 *
 * fdt_move() relocates, if possible, the device tree blob located at
 * fdt to the buffer at buf of size bufsize.  The buffer may overlap
 * with the existing device tree blob at fdt.  Therefore,
 *     fdt_move(fdt, fdt, fdt_totalsize(fdt))
 * should always succeed.
 *
 * returns:
 *     0, on success
 *     -FDT_ERR_NOSPACE, bufsize is insufficient to contain the device tree
 *     -FDT_ERR_BADMAGIC,
 *     -FDT_ERR_BADVERSION,
 *     -FDT_ERR_BADSTATE, standard meanings
 */
int fdt_move(const void *fdt, void *buf, int bufsize);

/**********************************************************************/
/* Read-only functions                                                */
/**********************************************************************/

/**
 * fdt_string - retrieve a string from the strings block of a device tree
 * @fdt: pointer to the device tree blob
 * @stroffset: offset of the string within the strings block (native endian)
 *
 * fdt_string() retrieves a pointer to a single string from the
 * strings block of the device tree blob at fdt.
 *
 * returns:
 *     a pointer to the string, on success
 *     NULL, if stroffset is out of bounds
 */
const char *fdt_string(const void *fdt, int stroffset);

/**
 * fdt_get_max_phandle - retrieves the highest phandle in a tree
 * @fdt: pointer to the device tree blob
 *
 * fdt_get_max_phandle retrieves the highest phandle in the given
 * device tree
 *
 * returns:
 *      the highest phandle on success
 *      0, if an error occurred
 */
uint32_t fdt_get_max_phandle(const void *fdt);

/**
 * fdt_num_mem_rsv - retrieve the number of memory reserve map entries
 * @fdt: pointer to the device tree blob
 *
 * Returns the number of entries in the device tree blob's memory
 * reservation map.  This does not include the terminating 0,0 entry
 * or any other (0,0) entries reserved for expansion.
 *
 * returns:
 *     the number of entries
 */
int fdt_num_mem_rsv(const void *fdt);

/**
 * fdt_get_mem_rsv - retrieve one memory reserve map entry
 * @fdt: pointer to the device tree blob
 * @address, @size: pointers to 64-bit variables
 *
 * On success, *address and *size will contain the address and size of
 * the n-th reserve map entry from the device tree blob, in
 * native-endian format.
 *
 * returns:
 *     0, on success
 *     -FDT_ERR_BADMAGIC,
 *     -FDT_ERR_BADVERSION,
 *     -FDT_ERR_BADSTATE, standard meanings
 */
int fdt_get_mem_rsv(const void *fdt, int n, uint64_t *address, uint64_t *size);

/**
 * fdt_subnode_offset_namelen - find a subnode based on substring
 * @fdt: pointer to the device tree blob
 * @parentoffset: structure block offset of a node
 * @name: name of the subnode to locate
 * @namelen: number of characters of name to consider
 *
 * Identical to fdt_subnode_offset(), but only examine the first
 * namelen characters of name for matching the subnode name.  This is
 * useful for finding subnodes based on a portion of a larger string,
 * such as a full path.
 */
int fdt_subnode_offset_namelen(const void *fdt, int parentoffset,
                               const char *name, int namelen);
/**
 * fdt_subnode_offset - find a subnode of a given node
 * @fdt: pointer to the device tree blob
 * @parentoffset: structure block offset of a node
 * @name: name of the subnode to locate
 *
 * fdt_subnode_offset() finds a subnode of the node at structure block
 * offset parentoffset with the given name.  name may include a unit
 * address, in which case fdt_subnode_offset() will find the subnode
 * with that unit address, or the unit address may be omitted, in
 * which case fdt_subnode_offset() will find an arbitrary subnode
 * whose name excluding unit address matches the given name.
 *
 * returns:
 *      structure block offset of the requested subnode (>=0), on success
 *      -FDT_ERR_NOTFOUND, if the requested subnode does not exist
 *      -FDT_ERR_BADOFFSET, if parentoffset did not point to an FDT_BEGIN_NODE tag
 *      -FDT_ERR_BADMAGIC,
 *      -FDT_ERR_BADVERSION,
 *      -FDT_ERR_BADSTATE,
 *      -FDT_ERR_BADSTRUCTURE,
 *      -FDT_ERR_TRUNCATED, standard meanings.
 */
int fdt_subnode_offset(const void *fdt, int parentoffset, const char *name);

/**
 * fdt_path_offset - find a tree node by its full path
 * @fdt: pointer to the device tree blob
 * @path: full path of the node to locate
 *
 * fdt_path_offset() finds a node of a given path in the device tree.
 * Each path component may omit the unit address portion, but the
 * results of this are undefined if any such path component is
 * ambiguous (that is if there are multiple nodes at the relevant
 * level matching the given component, differentiated only by unit
 * address).
 *
 * returns:
 *      structure block offset of the node with the requested path (>=0), on success
 *      -FDT_ERR_BADPATH, given path does not begin with '/' or is invalid
 *      -FDT_ERR_NOTFOUND, if the requested node does not exist
 *      -FDT_ERR_BADMAGIC,
 *      -FDT_ERR_BADVERSION,
 *      -FDT_ERR_BADSTATE,
 *      -FDT_ERR_BADSTRUCTURE,
 *      -FDT_ERR_TRUNCATED, standard meanings.
 */
int fdt_path_offset(const void *fdt, const char *path);

/**
 * fdt_get_name - retrieve the name of a given node
 * @fdt: pointer to the device tree blob
 * @nodeoffset: structure block offset of the starting node
 * @lenp: pointer to an integer variable (will be overwritten) or NULL
 *
 * fdt_get_name() retrieves the name (including unit address) of the
 * device tree node at structure block offset nodeoffset.  If lenp is
 * non-NULL, the length of this name is also returned, in the integer
 * pointed to by lenp.
 *
 * returns:
 *      pointer to the node's name, on success
 *              If lenp is non-NULL, *lenp contains the length of that name (>=0)
 *      NULL, on error
 *              if lenp is non-NULL *lenp contains an error code (<0):
 *              -FDT_ERR_BADOFFSET, nodeoffset did not point to FDT_BEGIN_NODE tag
 *              -FDT_ERR_BADMAGIC,
 *              -FDT_ERR_BADVERSION,
 *              -FDT_ERR_BADSTATE, standard meanings
 */
const char *fdt_get_name(const void *fdt, int nodeoffset, int *lenp);

/**
 * fdt_first_property_offset - find the offset of a node's first property
 * @fdt: pointer to the device tree blob
 * @nodeoffset: structure block offset of a node
 *
 * fdt_first_property_offset() finds the first property of the node at
 * the given structure block offset.
 *
 * returns:
 *      structure block offset of the property (>=0), on success
 *      -FDT_ERR_NOTFOUND, if the requested node has no properties
 *      -FDT_ERR_BADOFFSET, if nodeoffset did not point to an FDT_BEGIN_NODE tag
 *      -FDT_ERR_BADMAGIC,
 *      -FDT_ERR_BADVERSION,
 *      -FDT_ERR_BADSTATE,
 *      -FDT_ERR_BADSTRUCTURE,
 *      -FDT_ERR_TRUNCATED, standard meanings.
 */
int fdt_first_property_offset(const void *fdt, int nodeoffset);

/**
 * fdt_next_property_offset - step through a node's properties
 * @fdt: pointer to the device tree blob
 * @offset: structure block offset of a property
 *
 * fdt_next_property_offset() finds the property immediately after the
 * one at the given structure block offset.  This will be a property
 * of the same node as the given property.
 *
 * returns:
 *      structure block offset of the next property (>=0), on success
 *      -FDT_ERR_NOTFOUND, if the given property is the last in its node
 *      -FDT_ERR_BADOFFSET, if nodeoffset did not point to an FDT_PROP tag
 *      -FDT_ERR_BADMAGIC,
 *      -FDT_ERR_BADVERSION,
 *      -FDT_ERR_BADSTATE,
 *      -FDT_ERR_BADSTRUCTURE,
 *      -FDT_ERR_TRUNCATED, standard meanings.
 */
int fdt_next_property_offset(const void *fdt, int offset);

/**
 * fdt_for_each_property - iterate over all properties of a node
 * @property_offset:    property offset (int)
 * @fdt:                FDT blob (const void *)
 * @node:               node offset (int)
 *
 * This is actually a wrapper around a for loop and would be used like so:
 *
 *      fdt_for_each_property(fdt, node, property) {
 *              ...
 *              use property
 *              ...
 *      }
 *
 * Note that this is implemented as a macro and property is used as
 * iterator in the loop. It should therefore be a locally allocated
 * variable. The node variable on the other hand is never modified, so
 * it can be constant or even a literal.
 */
#define fdt_for_each_property_offset(property, fdt, node)       \
        for (property = fdt_first_property_offset(fdt, node);   \
             property >= 0;                                     \
             property = fdt_next_property_offset(fdt, property))

/**
 * fdt_get_property_by_offset - retrieve the property at a given offset
 * @fdt: pointer to the device tree blob
 * @offset: offset of the property to retrieve
 * @lenp: pointer to an integer variable (will be overwritten) or NULL
 *
 * fdt_get_property_by_offset() retrieves a pointer to the
 * fdt_property structure within the device tree blob at the given
 * offset.  If lenp is non-NULL, the length of the property value is
 * also returned, in the integer pointed to by lenp.
 *
 * returns:
 *      pointer to the structure representing the property
 *              if lenp is non-NULL, *lenp contains the length of the property
 *              value (>=0)
 *      NULL, on error
 *              if lenp is non-NULL, *lenp contains an error code (<0):
 *              -FDT_ERR_BADOFFSET, nodeoffset did not point to FDT_PROP tag
 *              -FDT_ERR_BADMAGIC,
 *              -FDT_ERR_BADVERSION,
 *              -FDT_ERR_BADSTATE,
 *              -FDT_ERR_BADSTRUCTURE,
 *              -FDT_ERR_TRUNCATED, standard meanings
 */
const struct fdt_property *fdt_get_property_by_offset(const void *fdt,
                                                      int offset,
                                                      int *lenp);

/**
 * fdt_get_property_namelen - find a property based on substring
 * @fdt: pointer to the device tree blob
 * @nodeoffset: offset of the node whose property to find
 * @name: name of the property to find
 * @namelen: number of characters of name to consider
 * @lenp: pointer to an integer variable (will be overwritten) or NULL
 *
 * Identical to fdt_get_property_namelen(), but only examine the first
 * namelen characters of name for matching the property name.
 */
const struct fdt_property *fdt_get_property_namelen(const void *fdt,
                                                    int nodeoffset,
                                                    const char *name,
                                                    int namelen, int *lenp);

/**
 * fdt_get_property - find a given property in a given node
 * @fdt: pointer to the device tree blob
 * @nodeoffset: offset of the node whose property to find
 * @name: name of the property to find
 * @lenp: pointer to an integer variable (will be overwritten) or NULL
 *
 * fdt_get_property() retrieves a pointer to the fdt_property
 * structure within the device tree blob corresponding to the property
 * named 'name' of the node at offset nodeoffset.  If lenp is
 * non-NULL, the length of the property value is also returned, in the
 * integer pointed to by lenp.
 *
 * returns:
 *      pointer to the structure representing the property
 *              if lenp is non-NULL, *lenp contains the length of the property
 *              value (>=0)
 *      NULL, on error
 *              if lenp is non-NULL, *lenp contains an error code (<0):
 *              -FDT_ERR_NOTFOUND, node does not have named property
 *              -FDT_ERR_BADOFFSET, nodeoffset did not point to FDT_BEGIN_NODE tag
 *              -FDT_ERR_BADMAGIC,
 *              -FDT_ERR_BADVERSION,
 *              -FDT_ERR_BADSTATE,
 *              -FDT_ERR_BADSTRUCTURE,
 *              -FDT_ERR_TRUNCATED, standard meanings
 */
const struct fdt_property *fdt_get_property(const void *fdt, int nodeoffset,
                                            const char *name, int *lenp);
static inline struct fdt_property *fdt_get_property_w(void *fdt, int nodeoffset,
                                                      const char *name,
                                                      int *lenp)
{
        return (struct fdt_property *)(uintptr_t)
                fdt_get_property(fdt, nodeoffset, name, lenp);
}

/**
 * fdt_getprop_by_offset - retrieve the value of a property at a given offset
 * @fdt: pointer to the device tree blob
 * @ffset: offset of the property to read
 * @namep: pointer to a string variable (will be overwritten) or NULL
 * @lenp: pointer to an integer variable (will be overwritten) or NULL
 *
 * fdt_getprop_by_offset() retrieves a pointer to the value of the
 * property at structure block offset 'offset' (this will be a pointer
 * to within the device blob itself, not a copy of the value).  If
 * lenp is non-NULL, the length of the property value is also
 * returned, in the integer pointed to by lenp.  If namep is non-NULL,
 * the property's namne will also be returned in the char * pointed to
 * by namep (this will be a pointer to within the device tree's string
 * block, not a new copy of the name).
 *
 * returns:
 *      pointer to the property's value
 *              if lenp is non-NULL, *lenp contains the length of the property
 *              value (>=0)
 *              if namep is non-NULL *namep contiains a pointer to the property
 *              name.
 *      NULL, on error
 *              if lenp is non-NULL, *lenp contains an error code (<0):
 *              -FDT_ERR_BADOFFSET, nodeoffset did not point to FDT_PROP tag
 *              -FDT_ERR_BADMAGIC,
 *              -FDT_ERR_BADVERSION,
 *              -FDT_ERR_BADSTATE,
 *              -FDT_ERR_BADSTRUCTURE,
 *              -FDT_ERR_TRUNCATED, standard meanings
 */
const void *fdt_getprop_by_offset(const void *fdt, int offset,
                                  const char **namep, int *lenp);

/**
 * fdt_getprop_namelen - get property value based on substring
 * @fdt: pointer to the device tree blob
 * @nodeoffset: offset of the node whose property to find
 * @name: name of the property to find
 * @namelen: number of characters of name to consider
 * @lenp: pointer to an integer variable (will be overwritten) or NULL
 *
 * Identical to fdt_getprop(), but only examine the first namelen
 * characters of name for matching the property name.
 */
const void *fdt_getprop_namelen(const void *fdt, int nodeoffset,
                                const char *name, int namelen, int *lenp);

/**
 * fdt_getprop - retrieve the value of a given property
 * @fdt: pointer to the device tree blob
 * @nodeoffset: offset of the node whose property to find
 * @name: name of the property to find
 * @lenp: pointer to an integer variable (will be overwritten) or NULL
 *
 * fdt_getprop() retrieves a pointer to the value of the property
 * named 'name' of the node at offset nodeoffset (this will be a
 * pointer to within the device blob itself, not a copy of the value).
 * If lenp is non-NULL, the length of the property value is also
 * returned, in the integer pointed to by lenp.
 *
 * returns:
 *      pointer to the property's value
 *              if lenp is non-NULL, *lenp contains the length of the property
 *              value (>=0)
 *      NULL, on error
 *              if lenp is non-NULL, *lenp contains an error code (<0):
 *              -FDT_ERR_NOTFOUND, node does not have named property
 *              -FDT_ERR_BADOFFSET, nodeoffset did not point to FDT_BEGIN_NODE tag
 *              -FDT_ERR_BADMAGIC,
 *              -FDT_ERR_BADVERSION,
 *              -FDT_ERR_BADSTATE,
 *              -FDT_ERR_BADSTRUCTURE,
 *              -FDT_ERR_TRUNCATED, standard meanings
 */
const void *fdt_getprop(const void *fdt, int nodeoffset,
                        const char *name, int *lenp);
static inline void *fdt_getprop_w(void *fdt, int nodeoffset,
                                  const char *name, int *lenp)
{
        return (void *)(uintptr_t)fdt_getprop(fdt, nodeoffset, name, lenp);
}

/**
 * fdt_get_phandle - retrieve the phandle of a given node
 * @fdt: pointer to the device tree blob
 * @nodeoffset: structure block offset of the node
 *
 * fdt_get_phandle() retrieves the phandle of the device tree node at
 * structure block offset nodeoffset.
 *
 * returns:
 *      the phandle of the node at nodeoffset, on success (!= 0, != -1)
 *      0, if the node has no phandle, or another error occurs
 */
uint32_t fdt_get_phandle(const void *fdt, int nodeoffset);

/**
 * fdt_get_alias_namelen - get alias based on substring
 * @fdt: pointer to the device tree blob
 * @name: name of the alias th look up
 * @namelen: number of characters of name to consider
 *
 * Identical to fdt_get_alias(), but only examine the first namelen
 * characters of name for matching the alias name.
 */
const char *fdt_get_alias_namelen(const void *fdt,
                                  const char *name, int namelen);

/**
 * fdt_get_alias - retreive the path referenced by a given alias
 * @fdt: pointer to the device tree blob
 * @name: name of the alias th look up
 *
 * fdt_get_alias() retrieves the value of a given alias.  That is, the
 * value of the property named 'name' in the node /aliases.
 *
 * returns:
 *      a pointer to the expansion of the alias named 'name', if it exists
 *      NULL, if the given alias or the /aliases node does not exist
 */
const char *fdt_get_alias(const void *fdt, const char *name);

/**
 * fdt_get_path - determine the full path of a node
 * @fdt: pointer to the device tree blob
 * @nodeoffset: offset of the node whose path to find
 * @buf: character buffer to contain the returned path (will be overwritten)
 * @buflen: size of the character buffer at buf
 *
 * fdt_get_path() computes the full path of the node at offset
 * nodeoffset, and records that path in the buffer at buf.
 *
 * NOTE: This function is expensive, as it must scan the device tree
 * structure from the start to nodeoffset.
 *
 * returns:
 *      0, on success
 *              buf contains the absolute path of the node at
 *              nodeoffset, as a NUL-terminated string.
 *      -FDT_ERR_BADOFFSET, nodeoffset does not refer to a BEGIN_NODE tag
 *      -FDT_ERR_NOSPACE, the path of the given node is longer than (bufsize-1)
 *              characters and will not fit in the given buffer.
 *      -FDT_ERR_BADMAGIC,
 *      -FDT_ERR_BADVERSION,
 *      -FDT_ERR_BADSTATE,
 *      -FDT_ERR_BADSTRUCTURE, standard meanings
 */
int fdt_get_path(const void *fdt, int nodeoffset, char *buf, int buflen);

/**
 * fdt_supernode_atdepth_offset - find a specific ancestor of a node
 * @fdt: pointer to the device tree blob
 * @nodeoffset: offset of the node whose parent to find
 * @supernodedepth: depth of the ancestor to find
 * @nodedepth: pointer to an integer variable (will be overwritten) or NULL
 *
 * fdt_supernode_atdepth_offset() finds an ancestor of the given node
 * at a specific depth from the root (where the root itself has depth
 * 0, its immediate subnodes depth 1 and so forth).  So
 *      fdt_supernode_atdepth_offset(fdt, nodeoffset, 0, NULL);
 * will always return 0, the offset of the root node.  If the node at
 * nodeoffset has depth D, then:
 *      fdt_supernode_atdepth_offset(fdt, nodeoffset, D, NULL);
 * will return nodeoffset itself.
 *
 * NOTE: This function is expensive, as it must scan the device tree
 * structure from the start to nodeoffset.
 *
 * returns:

 *      structure block offset of the node at node offset's ancestor
 *              of depth supernodedepth (>=0), on success
 *      -FDT_ERR_BADOFFSET, nodeoffset does not refer to a BEGIN_NODE tag
*       -FDT_ERR_NOTFOUND, supernodedepth was greater than the depth of nodeoffset
 *      -FDT_ERR_BADMAGIC,
 *      -FDT_ERR_BADVERSION,
 *      -FDT_ERR_BADSTATE,
 *      -FDT_ERR_BADSTRUCTURE, standard meanings
 */
int fdt_supernode_atdepth_offset(const void *fdt, int nodeoffset,
                                 int supernodedepth, int *nodedepth);

/**
 * fdt_node_depth - find the depth of a given node
 * @fdt: pointer to the device tree blob
 * @nodeoffset: offset of the node whose parent to find
 *
 * fdt_node_depth() finds the depth of a given node.  The root node
 * has depth 0, its immediate subnodes depth 1 and so forth.
 *
 * NOTE: This function is expensive, as it must scan the device tree
 * structure from the start to nodeoffset.
 *
 * returns:
 *      depth of the node at nodeoffset (>=0), on success
 *      -FDT_ERR_BADOFFSET, nodeoffset does not refer to a BEGIN_NODE tag
 *      -FDT_ERR_BADMAGIC,
 *      -FDT_ERR_BADVERSION,
 *      -FDT_ERR_BADSTATE,
 *      -FDT_ERR_BADSTRUCTURE, standard meanings
 */
int fdt_node_depth(const void *fdt, int nodeoffset);

/**
 * fdt_parent_offset - find the parent of a given node
 * @fdt: pointer to the device tree blob
 * @nodeoffset: offset of the node whose parent to find
 *
 * fdt_parent_offset() locates the parent node of a given node (that
 * is, it finds the offset of the node which contains the node at
 * nodeoffset as a subnode).
 *
 * NOTE: This function is expensive, as it must scan the device tree
 * structure from the start to nodeoffset, *twice*.
 *
 * returns:
 *      structure block offset of the parent of the node at nodeoffset
 *              (>=0), on success
 *      -FDT_ERR_BADOFFSET, nodeoffset does not refer to a BEGIN_NODE tag
 *      -FDT_ERR_BADMAGIC,
 *      -FDT_ERR_BADVERSION,
 *      -FDT_ERR_BADSTATE,
 *      -FDT_ERR_BADSTRUCTURE, standard meanings
 */
int fdt_parent_offset(const void *fdt, int nodeoffset);

/**
 * fdt_node_offset_by_prop_value - find nodes with a given property value
 * @fdt: pointer to the device tree blob
 * @startoffset: only find nodes after this offset
 * @propname: property name to check
 * @propval: property value to search for
 * @proplen: length of the value in propval
 *
 * fdt_node_offset_by_prop_value() returns the offset of the first
 * node after startoffset, which has a property named propname whose
 * value is of length proplen and has value equal to propval; or if
 * startoffset is -1, the very first such node in the tree.
 *
 * To iterate through all nodes matching the criterion, the following
 * idiom can be used:
 *      offset = fdt_node_offset_by_prop_value(fdt, -1, propname,
 *                                             propval, proplen);
 *      while (offset != -FDT_ERR_NOTFOUND) {
 *              // other code here
 *              offset = fdt_node_offset_by_prop_value(fdt, offset, propname,
 *                                                     propval, proplen);
 *      }
 *
 * Note the -1 in the first call to the function, if 0 is used here
 * instead, the function will never locate the root node, even if it
 * matches the criterion.
 *
 * returns:
 *      structure block offset of the located node (>= 0, >startoffset),
 *               on success
 *      -FDT_ERR_NOTFOUND, no node matching the criterion exists in the
 *              tree after startoffset
 *      -FDT_ERR_BADOFFSET, nodeoffset does not refer to a BEGIN_NODE tag
 *      -FDT_ERR_BADMAGIC,
 *      -FDT_ERR_BADVERSION,
 *      -FDT_ERR_BADSTATE,
 *      -FDT_ERR_BADSTRUCTURE, standard meanings
 */
int fdt_node_offset_by_prop_value(const void *fdt, int startoffset,
                                  const char *propname,
                                  const void *propval, int proplen);

/**
 * fdt_node_offset_by_phandle - find the node with a given phandle
 * @fdt: pointer to the device tree blob
 * @phandle: phandle value
 *
 * fdt_node_offset_by_phandle() returns the offset of the node
 * which has the given phandle value.  If there is more than one node
 * in the tree with the given phandle (an invalid tree), results are
 * undefined.
 *
 * returns:
 *      structure block offset of the located node (>= 0), on success
 *      -FDT_ERR_NOTFOUND, no node with that phandle exists
 *      -FDT_ERR_BADPHANDLE, given phandle value was invalid (0 or -1)
 *      -FDT_ERR_BADMAGIC,
 *      -FDT_ERR_BADVERSION,
 *      -FDT_ERR_BADSTATE,
 *      -FDT_ERR_BADSTRUCTURE, standard meanings
 */
int fdt_node_offset_by_phandle(const void *fdt, uint32_t phandle);

/**
 * fdt_node_check_compatible: check a node's compatible property
 * @fdt: pointer to the device tree blob
 * @nodeoffset: offset of a tree node
 * @compatible: string to match against
 *
 *
 * fdt_node_check_compatible() returns 0 if the given node contains a
 * 'compatible' property with the given string as one of its elements,
 * it returns non-zero otherwise, or on error.
 *
 * returns:
 *      0, if the node has a 'compatible' property listing the given string
 *      1, if the node has a 'compatible' property, but it does not list
 *              the given string
 *      -FDT_ERR_NOTFOUND, if the given node has no 'compatible' property
 *      -FDT_ERR_BADOFFSET, if nodeoffset does not refer to a BEGIN_NODE tag
 *      -FDT_ERR_BADMAGIC,
 *      -FDT_ERR_BADVERSION,
 *      -FDT_ERR_BADSTATE,
 *      -FDT_ERR_BADSTRUCTURE, standard meanings
 */
int fdt_node_check_compatible(const void *fdt, int nodeoffset,
                              const char *compatible);

/**
 * fdt_node_offset_by_compatible - find nodes with a given 'compatible' value
 * @fdt: pointer to the device tree blob
 * @startoffset: only find nodes after this offset
 * @compatible: 'compatible' string to match against
 *
 * fdt_node_offset_by_compatible() returns the offset of the first
 * node after startoffset, which has a 'compatible' property which
 * lists the given compatible string; or if startoffset is -1, the
 * very first such node in the tree.
 *
 * To iterate through all nodes matching the criterion, the following
 * idiom can be used:
 *      offset = fdt_node_offset_by_compatible(fdt, -1, compatible);
 *      while (offset != -FDT_ERR_NOTFOUND) {
 *              // other code here
 *              offset = fdt_node_offset_by_compatible(fdt, offset, compatible);
 *      }
 *
 * Note the -1 in the first call to the function, if 0 is used here
 * instead, the function will never locate the root node, even if it
 * matches the criterion.
 *
 * returns:
 *      structure block offset of the located node (>= 0, >startoffset),
 *               on success
 *      -FDT_ERR_NOTFOUND, no node matching the criterion exists in the
 *              tree after startoffset
 *      -FDT_ERR_BADOFFSET, nodeoffset does not refer to a BEGIN_NODE tag
 *      -FDT_ERR_BADMAGIC,
 *      -FDT_ERR_BADVERSION,
 *      -FDT_ERR_BADSTATE,
 *      -FDT_ERR_BADSTRUCTURE, standard meanings
 */
int fdt_node_offset_by_compatible(const void *fdt, int startoffset,
                                  const char *compatible);

/**
 * fdt_stringlist_contains - check a string list property for a string
 * @strlist: Property containing a list of strings to check
 * @listlen: Length of property
 * @str: String to search for
 *
 * This is a utility function provided for convenience. The list contains
 * one or more strings, each terminated by \0, as is found in a device tree
 * "compatible" property.
 *
 * @return: 1 if the string is found in the list, 0 not found, or invalid list
 */
int fdt_stringlist_contains(const char *strlist, int listlen, const char *str);

/**
 * fdt_count_strings - count the number of strings in a string list
 * @fdt: pointer to the device tree blob
 * @node: offset of the node
 * @property: name of the property containing the string list
 * @return: the number of strings in the given property
 */
int fdt_count_strings(const void *fdt, int node, const char *property);

/**
 * fdt_find_string - find a string in a string list and return its index
 * @fdt: pointer to the device tree blob
 * @node: offset of the node
 * @property: name of the property containing the string list
 * @string: string to look up in the string list
 * @return: the index of the string or negative on error
 */
int fdt_find_string(const void *fdt, int node, const char *property,
                    const char *string);

/**
 * fdt_get_string_index() - obtain the string at a given index in a string list
 * @fdt: pointer to the device tree blob
 * @node: offset of the node
 * @property: name of the property containing the string list
 * @index: index of the string to return
 * @output: return location for the string
 * @return: 0 if the string was found or a negative error code otherwise
 */
int fdt_get_string_index(const void *fdt, int node, const char *property,
                         int index, const char **output);

/**
 * fdt_get_string() - obtain the first string in a string list
 * @fdt: pointer to the device tree blob
 * @node: offset of the node
 * @property: name of the property containing the string list
 * @output: return location for the string
 * @return: 0 if the string was found or a negative error code otherwise
 *
 * This is a shortcut for:
 *
 *      fdt_get_string_index(fdt, node, property, 0, output).
 */
int fdt_get_string(const void *fdt, int node, const char *property,
                   const char **output);

/**********************************************************************/
/* Read-only functions (addressing related)                           */
/**********************************************************************/

/**
 * FDT_MAX_NCELLS - maximum value for #address-cells and #size-cells
 *
 * This is the maximum value for #address-cells, #size-cells and
 * similar properties that will be processed by libfdt.  IEE1275
 * requires that OF implementations handle values up to 4.
 * Implementations may support larger values, but in practice higher
 * values aren't used.
 */
#define FDT_MAX_NCELLS          4

/**
 * fdt_address_cells - retrieve address size for a bus represented in the tree
 * @fdt: pointer to the device tree blob
 * @nodeoffset: offset of the node to find the address size for
 *
 * When the node has a valid #address-cells property, returns its value.
 *
 * returns:
 *      0 <= n < FDT_MAX_NCELLS, on success
 *      2, if the node has no #address-cells property
 *      -FDT_ERR_BADNCELLS, if the node has a badly formatted or invalid
 *              #address-cells property
 *      -FDT_ERR_BADMAGIC,
 *      -FDT_ERR_BADVERSION,
 *      -FDT_ERR_BADSTATE,
 *      -FDT_ERR_BADSTRUCTURE,
 *      -FDT_ERR_TRUNCATED, standard meanings
 */
int fdt_address_cells(const void *fdt, int nodeoffset);

/**
 * fdt_size_cells - retrieve address range size for a bus represented in the
 *                  tree
 * @fdt: pointer to the device tree blob
 * @nodeoffset: offset of the node to find the address range size for
 *
 * When the node has a valid #size-cells property, returns its value.
 *
 * returns:
 *      0 <= n < FDT_MAX_NCELLS, on success
 *      2, if the node has no #address-cells property
 *      -FDT_ERR_BADNCELLS, if the node has a badly formatted or invalid
 *              #size-cells property
 *      -FDT_ERR_BADMAGIC,
 *      -FDT_ERR_BADVERSION,
 *      -FDT_ERR_BADSTATE,
 *      -FDT_ERR_BADSTRUCTURE,
 *      -FDT_ERR_TRUNCATED, standard meanings
 */
int fdt_size_cells(const void *fdt, int nodeoffset);


/**********************************************************************/
/* Write-in-place functions                                           */
/**********************************************************************/

/**
 * fdt_setprop_inplace - change a property's value, but not its size
 * @fdt: pointer to the device tree blob
 * @nodeoffset: offset of the node whose property to change
 * @name: name of the property to change
 * @val: pointer to data to replace the property value with
 * @len: length of the property value
 *
 * fdt_setprop_inplace() replaces the value of a given property with
 * the data in val, of length len.  This function cannot change the
 * size of a property, and so will only work if len is equal to the
 * current length of the property.
 *
 * This function will alter only the bytes in the blob which contain
 * the given property value, and will not alter or move any other part
 * of the tree.
 *
 * returns:
 *      0, on success
 *      -FDT_ERR_NOSPACE, if len is not equal to the property's current length
 *      -FDT_ERR_NOTFOUND, node does not have the named property
 *      -FDT_ERR_BADOFFSET, nodeoffset did not point to FDT_BEGIN_NODE tag
 *      -FDT_ERR_BADMAGIC,
 *      -FDT_ERR_BADVERSION,
 *      -FDT_ERR_BADSTATE,
 *      -FDT_ERR_BADSTRUCTURE,
 *      -FDT_ERR_TRUNCATED, standard meanings
 */
int fdt_setprop_inplace(void *fdt, int nodeoffset, const char *name,
                        const void *val, int len);

/**
 * fdt_setprop_inplace_u32 - change the value of a 32-bit integer property
 * @fdt: pointer to the device tree blob
 * @nodeoffset: offset of the node whose property to change
 * @name: name of the property to change
 * @val: 32-bit integer value to replace the property with
 *
 * fdt_setprop_inplace_u32() replaces the value of a given property
 * with the 32-bit integer value in val, converting val to big-endian
 * if necessary.  This function cannot change the size of a property,
 * and so will only work if the property already exists and has length
 * 4.
 *
 * This function will alter only the bytes in the blob which contain
 * the given property value, and will not alter or move any other part
 * of the tree.
 *
 * returns:
 *      0, on success
 *      -FDT_ERR_NOSPACE, if the property's length is not equal to 4
 *      -FDT_ERR_NOTFOUND, node does not have the named property
 *      -FDT_ERR_BADOFFSET, nodeoffset did not point to FDT_BEGIN_NODE tag
 *      -FDT_ERR_BADMAGIC,
 *      -FDT_ERR_BADVERSION,
 *      -FDT_ERR_BADSTATE,
 *      -FDT_ERR_BADSTRUCTURE,
 *      -FDT_ERR_TRUNCATED, standard meanings
 */
static inline int fdt_setprop_inplace_u32(void *fdt, int nodeoffset,
                                          const char *name, uint32_t val)
{
        fdt32_t tmp = cpu_to_fdt32(val);
        return fdt_setprop_inplace(fdt, nodeoffset, name, &tmp, sizeof(tmp));
}

/**
 * fdt_setprop_inplace_u64 - change the value of a 64-bit integer property
 * @fdt: pointer to the device tree blob
 * @nodeoffset: offset of the node whose property to change
 * @name: name of the property to change
 * @val: 64-bit integer value to replace the property with
 *
 * fdt_setprop_inplace_u64() replaces the value of a given property
 * with the 64-bit integer value in val, converting val to big-endian
 * if necessary.  This function cannot change the size of a property,
 * and so will only work if the property already exists and has length
 * 8.
 *
 * This function will alter only the bytes in the blob which contain
 * the given property value, and will not alter or move any other part
 * of the tree.
 *
 * returns:
 *      0, on success
 *      -FDT_ERR_NOSPACE, if the property's length is not equal to 8
 *      -FDT_ERR_NOTFOUND, node does not have the named property
 *      -FDT_ERR_BADOFFSET, nodeoffset did not point to FDT_BEGIN_NODE tag
 *      -FDT_ERR_BADMAGIC,
 *      -FDT_ERR_BADVERSION,
 *      -FDT_ERR_BADSTATE,
 *      -FDT_ERR_BADSTRUCTURE,
 *      -FDT_ERR_TRUNCATED, standard meanings
 */
static inline int fdt_setprop_inplace_u64(void *fdt, int nodeoffset,
                                          const char *name, uint64_t val)
{
        fdt64_t tmp = cpu_to_fdt64(val);
        return fdt_setprop_inplace(fdt, nodeoffset, name, &tmp, sizeof(tmp));
}

/**
 * fdt_setprop_inplace_cell - change the value of a single-cell property
 *
 * This is an alternative name for fdt_setprop_inplace_u32()
 */
static inline int fdt_setprop_inplace_cell(void *fdt, int nodeoffset,
                                           const char *name, uint32_t val)
{
        return fdt_setprop_inplace_u32(fdt, nodeoffset, name, val);
}

/**
 * fdt_nop_property - replace a property with nop tags
 * @fdt: pointer to the device tree blob
 * @nodeoffset: offset of the node whose property to nop
 * @name: name of the property to nop
 *
 * fdt_nop_property() will replace a given property's representation
 * in the blob with FDT_NOP tags, effectively removing it from the
 * tree.
 *
 * This function will alter only the bytes in the blob which contain
 * the property, and will not alter or move any other part of the
 * tree.
 *
 * returns:
 *      0, on success
 *      -FDT_ERR_NOTFOUND, node does not have the named property
 *      -FDT_ERR_BADOFFSET, nodeoffset did not point to FDT_BEGIN_NODE tag
 *      -FDT_ERR_BADMAGIC,
 *      -FDT_ERR_BADVERSION,
 *      -FDT_ERR_BADSTATE,
 *      -FDT_ERR_BADSTRUCTURE,
 *      -FDT_ERR_TRUNCATED, standard meanings
 */
int fdt_nop_property(void *fdt, int nodeoffset, const char *name);

/**
 * fdt_nop_node - replace a node (subtree) with nop tags
 * @fdt: pointer to the device tree blob
 * @nodeoffset: offset of the node to nop
 *
 * fdt_nop_node() will replace a given node's representation in the
 * blob, including all its subnodes, if any, with FDT_NOP tags,
 * effectively removing it from the tree.
 *
 * This function will alter only the bytes in the blob which contain
 * the node and its properties and subnodes, and will not alter or
 * move any other part of the tree.
 *
 * returns:
 *      0, on success
 *      -FDT_ERR_BADOFFSET, nodeoffset did not point to FDT_BEGIN_NODE tag
 *      -FDT_ERR_BADMAGIC,
 *      -FDT_ERR_BADVERSION,
 *      -FDT_ERR_BADSTATE,
 *      -FDT_ERR_BADSTRUCTURE,
 *      -FDT_ERR_TRUNCATED, standard meanings
 */
int fdt_nop_node(void *fdt, int nodeoffset);

/**********************************************************************/
/* Sequential write functions                                         */
/**********************************************************************/

int fdt_create(void *buf, int bufsize);
int fdt_resize(void *fdt, void *buf, int bufsize);
int fdt_add_reservemap_entry(void *fdt, uint64_t addr, uint64_t size);
int fdt_finish_reservemap(void *fdt);
int fdt_begin_node(void *fdt, const char *name);
int fdt_property(void *fdt, const char *name, const void *val, int len);
static inline int fdt_property_u32(void *fdt, const char *name, uint32_t val)
{
        fdt32_t tmp = cpu_to_fdt32(val);
        return fdt_property(fdt, name, &tmp, sizeof(tmp));
}
static inline int fdt_property_u64(void *fdt, const char *name, uint64_t val)
{
        fdt64_t tmp = cpu_to_fdt64(val);
        return fdt_property(fdt, name, &tmp, sizeof(tmp));
}
static inline int fdt_property_cell(void *fdt, const char *name, uint32_t val)
{
        return fdt_property_u32(fdt, name, val);
}

/**
 * fdt_property_placeholder - add a new property and return a ptr to its value
 *
 * @fdt: pointer to the device tree blob
 * @name: name of property to add
 * @len: length of property value in bytes
 * @valp: returns a pointer to where where the value should be placed
 *
 * returns:
 *      0, on success
 *      -FDT_ERR_BADMAGIC,
 *      -FDT_ERR_NOSPACE, standard meanings
 */
int fdt_property_placeholder(void *fdt, const char *name, int len, void **valp);

#define fdt_property_string(fdt, name, str) \
        fdt_property(fdt, name, str, strlen(str)+1)
int fdt_end_node(void *fdt);
int fdt_finish(void *fdt);

/**********************************************************************/
/* Read-write functions                                               */
/**********************************************************************/

int fdt_create_empty_tree(void *buf, int bufsize);
int fdt_open_into(const void *fdt, void *buf, int bufsize);
int fdt_pack(void *fdt);

/**
 * fdt_add_mem_rsv - add one memory reserve map entry
 * @fdt: pointer to the device tree blob
 * @address, @size: 64-bit values (native endian)
 *
 * Adds a reserve map entry to the given blob reserving a region at
 * address address of length size.
 *
 * This function will insert data into the reserve map and will
 * therefore change the indexes of some entries in the table.
 *
 * returns:
 *      0, on success
 *      -FDT_ERR_NOSPACE, there is insufficient free space in the blob to
 *              contain the new reservation entry
 *      -FDT_ERR_BADMAGIC,
 *      -FDT_ERR_BADVERSION,
 *      -FDT_ERR_BADSTATE,
 *      -FDT_ERR_BADSTRUCTURE,
 *      -FDT_ERR_BADLAYOUT,
 *      -FDT_ERR_TRUNCATED, standard meanings
 */
int fdt_add_mem_rsv(void *fdt, uint64_t address, uint64_t size);

/**
 * fdt_del_mem_rsv - remove a memory reserve map entry
 * @fdt: pointer to the device tree blob
 * @n: entry to remove
 *
 * fdt_del_mem_rsv() removes the n-th memory reserve map entry from
 * the blob.
 *
 * This function will delete data from the reservation table and will
 * therefore change the indexes of some entries in the table.
 *
 * returns:
 *      0, on success
 *      -FDT_ERR_NOTFOUND, there is no entry of the given index (i.e. there
 *              are less than n+1 reserve map entries)
 *      -FDT_ERR_BADMAGIC,
 *      -FDT_ERR_BADVERSION,
 *      -FDT_ERR_BADSTATE,
 *      -FDT_ERR_BADSTRUCTURE,
 *      -FDT_ERR_BADLAYOUT,
 *      -FDT_ERR_TRUNCATED, standard meanings
 */
int fdt_del_mem_rsv(void *fdt, int n);

/**
 * fdt_set_name - change the name of a given node
 * @fdt: pointer to the device tree blob
 * @nodeoffset: structure block offset of a node
 * @name: name to give the node
 *
 * fdt_set_name() replaces the name (including unit address, if any)
 * of the given node with the given string.  NOTE: this function can't
 * efficiently check if the new name is unique amongst the given
 * node's siblings; results are undefined if this function is invoked
 * with a name equal to one of the given node's siblings.
 *
 * This function may insert or delete data from the blob, and will
 * therefore change the offsets of some existing nodes.
 *
 * returns:
 *      0, on success
 *      -FDT_ERR_NOSPACE, there is insufficient free space in the blob
 *              to contain the new name
 *      -FDT_ERR_BADOFFSET, nodeoffset did not point to FDT_BEGIN_NODE tag
 *      -FDT_ERR_BADMAGIC,
 *      -FDT_ERR_BADVERSION,
 *      -FDT_ERR_BADSTATE, standard meanings
 */
int fdt_set_name(void *fdt, int nodeoffset, const char *name);

/**
 * fdt_setprop - create or change a property
 * @fdt: pointer to the device tree blob
 * @nodeoffset: offset of the node whose property to change
 * @name: name of the property to change
 * @val: pointer to data to set the property value to
 * @len: length of the property value
 *
 * fdt_setprop() sets the value of the named property in the given
 * node to the given value and length, creating the property if it
 * does not already exist.
 *
 * This function may insert or delete data from the blob, and will
 * therefore change the offsets of some existing nodes.
 *
 * returns:
 *      0, on success
 *      -FDT_ERR_NOSPACE, there is insufficient free space in the blob to
 *              contain the new property value
 *      -FDT_ERR_BADOFFSET, nodeoffset did not point to FDT_BEGIN_NODE tag
 *      -FDT_ERR_BADLAYOUT,
 *      -FDT_ERR_BADMAGIC,
 *      -FDT_ERR_BADVERSION,
 *      -FDT_ERR_BADSTATE,
 *      -FDT_ERR_BADSTRUCTURE,
 *      -FDT_ERR_BADLAYOUT,
 *      -FDT_ERR_TRUNCATED, standard meanings
 */
int fdt_setprop(void *fdt, int nodeoffset, const char *name,
                const void *val, int len);

/**
 * fdt_setprop_u32 - set a property to a 32-bit integer
 * @fdt: pointer to the device tree blob
 * @nodeoffset: offset of the node whose property to change
 * @name: name of the property to change
 * @val: 32-bit integer value for the property (native endian)
 *
 * fdt_setprop_u32() sets the value of the named property in the given
 * node to the given 32-bit integer value (converting to big-endian if
 * necessary), or creates a new property with that value if it does
 * not already exist.
 *
 * This function may insert or delete data from the blob, and will
 * therefore change the offsets of some existing nodes.
 *
 * returns:
 *      0, on success
 *      -FDT_ERR_NOSPACE, there is insufficient free space in the blob to
 *              contain the new property value
 *      -FDT_ERR_BADOFFSET, nodeoffset did not point to FDT_BEGIN_NODE tag
 *      -FDT_ERR_BADLAYOUT,
 *      -FDT_ERR_BADMAGIC,
 *      -FDT_ERR_BADVERSION,
 *      -FDT_ERR_BADSTATE,
 *      -FDT_ERR_BADSTRUCTURE,
 *      -FDT_ERR_BADLAYOUT,
 *      -FDT_ERR_TRUNCATED, standard meanings
 */
static inline int fdt_setprop_u32(void *fdt, int nodeoffset, const char *name,
                                  uint32_t val)
{
        fdt32_t tmp = cpu_to_fdt32(val);
        return fdt_setprop(fdt, nodeoffset, name, &tmp, sizeof(tmp));
}

/**
 * fdt_setprop_u64 - set a property to a 64-bit integer
 * @fdt: pointer to the device tree blob
 * @nodeoffset: offset of the node whose property to change
 * @name: name of the property to change
 * @val: 64-bit integer value for the property (native endian)
 *
 * fdt_setprop_u64() sets the value of the named property in the given
 * node to the given 64-bit integer value (converting to big-endian if
 * necessary), or creates a new property with that value if it does
 * not already exist.
 *
 * This function may insert or delete data from the blob, and will
 * therefore change the offsets of some existing nodes.
 *
 * returns:
 *      0, on success
 *      -FDT_ERR_NOSPACE, there is insufficient free space in the blob to
 *              contain the new property value
 *      -FDT_ERR_BADOFFSET, nodeoffset did not point to FDT_BEGIN_NODE tag
 *      -FDT_ERR_BADLAYOUT,
 *      -FDT_ERR_BADMAGIC,
 *      -FDT_ERR_BADVERSION,
 *      -FDT_ERR_BADSTATE,
 *      -FDT_ERR_BADSTRUCTURE,
 *      -FDT_ERR_BADLAYOUT,
 *      -FDT_ERR_TRUNCATED, standard meanings
 */
static inline int fdt_setprop_u64(void *fdt, int nodeoffset, const char *name,
                                  uint64_t val)
{
        fdt64_t tmp = cpu_to_fdt64(val);
        return fdt_setprop(fdt, nodeoffset, name, &tmp, sizeof(tmp));
}

/**
 * fdt_setprop_cell - set a property to a single cell value
 *
 * This is an alternative name for fdt_setprop_u32()
 */
static inline int fdt_setprop_cell(void *fdt, int nodeoffset, const char *name,
                                   uint32_t val)
{
        return fdt_setprop_u32(fdt, nodeoffset, name, val);
}

/**
 * fdt_setprop_string - set a property to a string value
 * @fdt: pointer to the device tree blob
 * @nodeoffset: offset of the node whose property to change
 * @name: name of the property to change
 * @str: string value for the property
 *
 * fdt_setprop_string() sets the value of the named property in the
 * given node to the given string value (using the length of the
 * string to determine the new length of the property), or creates a
 * new property with that value if it does not already exist.
 *
 * This function may insert or delete data from the blob, and will
 * therefore change the offsets of some existing nodes.
 *
 * returns:
 *      0, on success
 *      -FDT_ERR_NOSPACE, there is insufficient free space in the blob to
 *              contain the new property value
 *      -FDT_ERR_BADOFFSET, nodeoffset did not point to FDT_BEGIN_NODE tag
 *      -FDT_ERR_BADLAYOUT,
 *      -FDT_ERR_BADMAGIC,
 *      -FDT_ERR_BADVERSION,
 *      -FDT_ERR_BADSTATE,
 *      -FDT_ERR_BADSTRUCTURE,
 *      -FDT_ERR_BADLAYOUT,
 *      -FDT_ERR_TRUNCATED, standard meanings
 */
#define fdt_setprop_string(fdt, nodeoffset, name, str) \
        fdt_setprop((fdt), (nodeoffset), (name), (str), strlen(str)+1)

/**
 * fdt_appendprop - append to or create a property
 * @fdt: pointer to the device tree blob
 * @nodeoffset: offset of the node whose property to change
 * @name: name of the property to append to
 * @val: pointer to data to append to the property value
 * @len: length of the data to append to the property value
 *
 * fdt_appendprop() appends the value to the named property in the
 * given node, creating the property if it does not already exist.
 *
 * This function may insert data into the blob, and will therefore
 * change the offsets of some existing nodes.
 *
 * returns:
 *      0, on success
 *      -FDT_ERR_NOSPACE, there is insufficient free space in the blob to
 *              contain the new property value
 *      -FDT_ERR_BADOFFSET, nodeoffset did not point to FDT_BEGIN_NODE tag
 *      -FDT_ERR_BADLAYOUT,
 *      -FDT_ERR_BADMAGIC,
 *      -FDT_ERR_BADVERSION,
 *      -FDT_ERR_BADSTATE,
 *      -FDT_ERR_BADSTRUCTURE,
 *      -FDT_ERR_BADLAYOUT,
 *      -FDT_ERR_TRUNCATED, standard meanings
 */
int fdt_appendprop(void *fdt, int nodeoffset, const char *name,
                   const void *val, int len);

/**
 * fdt_appendprop_u32 - append a 32-bit integer value to a property
 * @fdt: pointer to the device tree blob
 * @nodeoffset: offset of the node whose property to change
 * @name: name of the property to change
 * @val: 32-bit integer value to append to the property (native endian)
 *
 * fdt_appendprop_u32() appends the given 32-bit integer value
 * (converting to big-endian if necessary) to the value of the named
 * property in the given node, or creates a new property with that
 * value if it does not already exist.
 *
 * This function may insert data into the blob, and will therefore
 * change the offsets of some existing nodes.
 *
 * returns:
 *      0, on success
 *      -FDT_ERR_NOSPACE, there is insufficient free space in the blob to
 *              contain the new property value
 *      -FDT_ERR_BADOFFSET, nodeoffset did not point to FDT_BEGIN_NODE tag
 *      -FDT_ERR_BADLAYOUT,
 *      -FDT_ERR_BADMAGIC,
 *      -FDT_ERR_BADVERSION,
 *      -FDT_ERR_BADSTATE,
 *      -FDT_ERR_BADSTRUCTURE,
 *      -FDT_ERR_BADLAYOUT,
 *      -FDT_ERR_TRUNCATED, standard meanings
 */
static inline int fdt_appendprop_u32(void *fdt, int nodeoffset,
                                     const char *name, uint32_t val)
{
        fdt32_t tmp = cpu_to_fdt32(val);
        return fdt_appendprop(fdt, nodeoffset, name, &tmp, sizeof(tmp));
}

/**
 * fdt_appendprop_u64 - append a 64-bit integer value to a property
 * @fdt: pointer to the device tree blob
 * @nodeoffset: offset of the node whose property to change
 * @name: name of the property to change
 * @val: 64-bit integer value to append to the property (native endian)
 *
 * fdt_appendprop_u64() appends the given 64-bit integer value
 * (converting to big-endian if necessary) to the value of the named
 * property in the given node, or creates a new property with that
 * value if it does not already exist.
 *
 * This function may insert data into the blob, and will therefore
 * change the offsets of some existing nodes.
 *
 * returns:
 *      0, on success
 *      -FDT_ERR_NOSPACE, there is insufficient free space in the blob to
 *              contain the new property value
 *      -FDT_ERR_BADOFFSET, nodeoffset did not point to FDT_BEGIN_NODE tag
 *      -FDT_ERR_BADLAYOUT,
 *      -FDT_ERR_BADMAGIC,
 *      -FDT_ERR_BADVERSION,
 *      -FDT_ERR_BADSTATE,
 *      -FDT_ERR_BADSTRUCTURE,
 *      -FDT_ERR_BADLAYOUT,
 *      -FDT_ERR_TRUNCATED, standard meanings
 */
static inline int fdt_appendprop_u64(void *fdt, int nodeoffset,
                                     const char *name, uint64_t val)
{
        fdt64_t tmp = cpu_to_fdt64(val);
        return fdt_appendprop(fdt, nodeoffset, name, &tmp, sizeof(tmp));
}

/**
 * fdt_appendprop_cell - append a single cell value to a property
 *
 * This is an alternative name for fdt_appendprop_u32()
 */
static inline int fdt_appendprop_cell(void *fdt, int nodeoffset,
                                      const char *name, uint32_t val)
{
        return fdt_appendprop_u32(fdt, nodeoffset, name, val);
}

/**
 * fdt_appendprop_string - append a string to a property
 * @fdt: pointer to the device tree blob
 * @nodeoffset: offset of the node whose property to change
 * @name: name of the property to change
 * @str: string value to append to the property
 *
 * fdt_appendprop_string() appends the given string to the value of
 * the named property in the given node, or creates a new property
 * with that value if it does not already exist.
 *
 * This function may insert data into the blob, and will therefore
 * change the offsets of some existing nodes.
 *
 * returns:
 *      0, on success
 *      -FDT_ERR_NOSPACE, there is insufficient free space in the blob to
 *              contain the new property value
 *      -FDT_ERR_BADOFFSET, nodeoffset did not point to FDT_BEGIN_NODE tag
 *      -FDT_ERR_BADLAYOUT,
 *      -FDT_ERR_BADMAGIC,
 *      -FDT_ERR_BADVERSION,
 *      -FDT_ERR_BADSTATE,
 *      -FDT_ERR_BADSTRUCTURE,
 *      -FDT_ERR_BADLAYOUT,
 *      -FDT_ERR_TRUNCATED, standard meanings
 */
#define fdt_appendprop_string(fdt, nodeoffset, name, str) \
        fdt_appendprop((fdt), (nodeoffset), (name), (str), strlen(str)+1)

/**
 * fdt_delprop - delete a property
 * @fdt: pointer to the device tree blob
 * @nodeoffset: offset of the node whose property to nop
 * @name: name of the property to nop
 *
 * fdt_del_property() will delete the given property.
 *
 * This function will delete data from the blob, and will therefore
 * change the offsets of some existing nodes.
 *
 * returns:
 *      0, on success
 *      -FDT_ERR_NOTFOUND, node does not have the named property
 *      -FDT_ERR_BADOFFSET, nodeoffset did not point to FDT_BEGIN_NODE tag
 *      -FDT_ERR_BADLAYOUT,
 *      -FDT_ERR_BADMAGIC,
 *      -FDT_ERR_BADVERSION,
 *      -FDT_ERR_BADSTATE,
 *      -FDT_ERR_BADSTRUCTURE,
 *      -FDT_ERR_TRUNCATED, standard meanings
 */
int fdt_delprop(void *fdt, int nodeoffset, const char *name);

/**
 * fdt_add_subnode_namelen - creates a new node based on substring
 * @fdt: pointer to the device tree blob
 * @parentoffset: structure block offset of a node
 * @name: name of the subnode to locate
 * @namelen: number of characters of name to consider
 *
 * Identical to fdt_add_subnode(), but use only the first namelen
 * characters of name as the name of the new node.  This is useful for
 * creating subnodes based on a portion of a larger string, such as a
 * full path.
 */
int fdt_add_subnode_namelen(void *fdt, int parentoffset,
                            const char *name, int namelen);

/**
 * fdt_add_subnode - creates a new node
 * @fdt: pointer to the device tree blob
 * @parentoffset: structure block offset of a node
 * @name: name of the subnode to locate
 *
 * fdt_add_subnode() creates a new node as a subnode of the node at
 * structure block offset parentoffset, with the given name (which
 * should include the unit address, if any).
 *
 * This function will insert data into the blob, and will therefore
 * change the offsets of some existing nodes.

 * returns:
 *      structure block offset of the created nodeequested subnode (>=0), on success
 *      -FDT_ERR_NOTFOUND, if the requested subnode does not exist
 *      -FDT_ERR_BADOFFSET, if parentoffset did not point to an FDT_BEGIN_NODE tag
 *      -FDT_ERR_EXISTS, if the node at parentoffset already has a subnode of
 *              the given name
 *      -FDT_ERR_NOSPACE, if there is insufficient free space in the
 *              blob to contain the new node
 *      -FDT_ERR_NOSPACE
 *      -FDT_ERR_BADLAYOUT
 *      -FDT_ERR_BADMAGIC,
 *      -FDT_ERR_BADVERSION,
 *      -FDT_ERR_BADSTATE,
 *      -FDT_ERR_BADSTRUCTURE,
 *      -FDT_ERR_TRUNCATED, standard meanings.
 */
int fdt_add_subnode(void *fdt, int parentoffset, const char *name);

/**
 * fdt_del_node - delete a node (subtree)
 * @fdt: pointer to the device tree blob
 * @nodeoffset: offset of the node to nop
 *
 * fdt_del_node() will remove the given node, including all its
 * subnodes if any, from the blob.
 *
 * This function will delete data from the blob, and will therefore
 * change the offsets of some existing nodes.
 *
 * returns:
 *      0, on success
 *      -FDT_ERR_BADOFFSET, nodeoffset did not point to FDT_BEGIN_NODE tag
 *      -FDT_ERR_BADLAYOUT,
 *      -FDT_ERR_BADMAGIC,
 *      -FDT_ERR_BADVERSION,
 *      -FDT_ERR_BADSTATE,
 *      -FDT_ERR_BADSTRUCTURE,
 *      -FDT_ERR_TRUNCATED, standard meanings
 */
int fdt_del_node(void *fdt, int nodeoffset);

/**********************************************************************/
/* Debugging / informational functions                                */
/**********************************************************************/

const char *fdt_strerror(int errval);

/**
 * fdt_remove_unused_strings() - Remove any unused strings from an FDT
 *
 * This creates a new device tree in @new with unused strings removed. The
 * called can then use fdt_pack() to minimise the space consumed.
 *
 * @old:        Old device tree blog
 * @new:        Place to put new device tree blob, which must be as large as
 *              @old
 * @return
 *      0, on success
 *      -FDT_ERR_BADOFFSET, corrupt device tree
 *      -FDT_ERR_NOSPACE, out of space, which should not happen unless there
 *              is something very wrong with the device tree input
 */
int fdt_remove_unused_strings(const void *old, void *new);

struct fdt_region {
        int offset;
        int size;
};

/*
 * Flags for fdt_find_regions()
 *
 * Add a region for the string table (always the last region)
 */
#define FDT_REG_ADD_STRING_TAB          (1 << 0)

/*
 * Add all supernodes of a matching node/property, useful for creating a
 * valid subset tree
 */
#define FDT_REG_SUPERNODES              (1 << 1)

/* Add the FDT_BEGIN_NODE tags of subnodes, including their names */
#define FDT_REG_DIRECT_SUBNODES (1 << 2)

/* Add all subnodes of a matching node */
#define FDT_REG_ALL_SUBNODES            (1 << 3)

/* Add a region for the mem_rsvmap table (always the first region) */
#define FDT_REG_ADD_MEM_RSVMAP          (1 << 4)

/* Indicates what an fdt part is (node, property, value) */
#define FDT_IS_NODE                     (1 << 0)
#define FDT_IS_PROP                     (1 << 1)
#define FDT_IS_VALUE                    (1 << 2)        /* not supported */
#define FDT_IS_COMPAT                   (1 << 3)        /* used internally */
#define FDT_NODE_HAS_PROP               (1 << 4)        /* node contains prop */

#define FDT_ANY_GLOBAL          (FDT_IS_NODE | FDT_IS_PROP | FDT_IS_VALUE | \
                                        FDT_IS_COMPAT)
#define FDT_IS_ANY                      0x1f            /* all the above */

/* We set a reasonable limit on the number of nested nodes */
#define FDT_MAX_DEPTH                   32

/* Decribes what we want to include from the current tag */
enum want_t {
        WANT_NOTHING,
        WANT_NODES_ONLY,                /* No properties */
        WANT_NODES_AND_PROPS,           /* Everything for one level */
        WANT_ALL_NODES_AND_PROPS        /* Everything for all levels */
};

/* Keeps track of the state at parent nodes */
struct fdt_subnode_stack {
        int offset;             /* Offset of node */
        enum want_t want;       /* The 'want' value here */
        int included;           /* 1 if we included this node, 0 if not */
};

struct fdt_region_ptrs {
        int depth;                      /* Current tree depth */
        int done;                       /* What we have completed scanning */
        enum want_t want;               /* What we are currently including */
        char *end;                      /* Pointer to end of full node path */
        int nextoffset;                 /* Next node offset to check */
};

/* The state of our finding algortihm */
struct fdt_region_state {
        struct fdt_subnode_stack stack[FDT_MAX_DEPTH];  /* node stack */
        struct fdt_region *region;      /* Contains list of regions found */
        int count;                      /* Numnber of regions found */
        const void *fdt;                /* FDT blob */
        int max_regions;                /* Maximum regions to find */
        int can_merge;          /* 1 if we can merge with previous region */
        int start;                      /* Start position of current region */
        struct fdt_region_ptrs ptrs;    /* Pointers for what we are up to */
};

/**
 * fdt_find_regions() - find regions in device tree
 *
 * Given a list of nodes to include and properties to exclude, find
 * the regions of the device tree which describe those included parts.
 *
 * The intent is to get a list of regions which will be invariant provided
 * those parts are invariant. For example, if you request a list of regions
 * for all nodes but exclude the property "data", then you will get the
 * same region contents regardless of any change to "data" properties.
 *
 * This function can be used to produce a byte-stream to send to a hashing
 * function to verify that critical parts of the FDT have not changed.
 *
 * Nodes which are given in 'inc' are included in the region list, as
 * are the names of the immediate subnodes nodes (but not the properties
 * or subnodes of those subnodes).
 *
 * For eaxample "/" means to include the root node, all root properties
 * and the FDT_BEGIN_NODE and FDT_END_NODE of all subnodes of /. The latter
 * ensures that we capture the names of the subnodes. In a hashing situation
 * it prevents the root node from changing at all Any change to non-excluded
 * properties, names of subnodes or number of subnodes would be detected.
 *
 * When used with FITs this provides the ability to hash and sign parts of
 * the FIT based on different configurations in the FIT. Then it is
 * impossible to change anything about that configuration (include images
 * attached to the configuration), but it may be possible to add new
 * configurations, new images or new signatures within the existing
 * framework.
 *
 * Adding new properties to a device tree may result in the string table
 * being extended (if the new property names are different from those
 * already added). This function can optionally include a region for
 * the string table so that this can be part of the hash too.
 *
 * The device tree header is not included in the list.
 *
 * @fdt:        Device tree to check
 * @inc:        List of node paths to included
 * @inc_count:  Number of node paths in list
 * @exc_prop:   List of properties names to exclude
 * @exc_prop_count:     Number of properties in exclude list
 * @region:     Returns list of regions
 * @max_region: Maximum length of region list
 * @path:       Pointer to a temporary string for the function to use for
 *              building path names
 * @path_len:   Length of path, must be large enough to hold the longest
 *              path in the tree
 * @add_string_tab:     1 to add a region for the string table
 * @return number of regions in list. If this is >max_regions then the
 * region array was exhausted. You should increase max_regions and try
 * the call again.
 */
int fdt_find_regions(const void *fdt, char * const inc[], int inc_count,
                     char * const exc_prop[], int exc_prop_count,
                     struct fdt_region region[], int max_regions,
                     char *path, int path_len, int add_string_tab);

/**
 * fdt_first_region() - find regions in device tree
 *
 * Given a nodes and properties to include and properties to exclude, find
 * the regions of the device tree which describe those included parts.
 *
 * The use for this function is twofold. Firstly it provides a convenient
 * way of performing a structure-aware grep of the tree. For example it is
 * possible to grep for a node and get all the properties associated with
 * that node. Trees can be subsetted easily, by specifying the nodes that
 * are required, and then writing out the regions returned by this function.
 * This is useful for small resource-constrained systems, such as boot
 * loaders, which want to use an FDT but do not need to know about all of
 * it.
 *
 * Secondly it makes it easy to hash parts of the tree and detect changes.
 * The intent is to get a list of regions which will be invariant provided
 * those parts are invariant. For example, if you request a list of regions
 * for all nodes but exclude the property "data", then you will get the
 * same region contents regardless of any change to "data" properties.
 *
 * This function can be used to produce a byte-stream to send to a hashing
 * function to verify that critical parts of the FDT have not changed.
 * Note that semantically null changes in order could still cause false
 * hash misses. Such reordering might happen if the tree is regenerated
 * from source, and nodes are reordered (the bytes-stream will be emitted
 * in a different order and mnay hash functions will detect this). However
 * if an existing tree is modified using libfdt functions, such as
 * fdt_add_subnode() and fdt_setprop(), then this problem is avoided.
 *
 * The nodes/properties to include/exclude are defined by a function
 * provided by the caller. This function is called for each node and
 * property, and must return:
 *
 *    0 - to exclude this part
 *    1 - to include this part
 *   -1 - for FDT_IS_PROP only: no information is available, so include
 *              if its containing node is included
 *
 * The last case is only used to deal with properties. Often a property is
 * included if its containing node is included - this is the case where
 * -1 is returned.. However if the property is specifically required to be
 * included/excluded, then 0 or 1 can be returned. Note that including a
 * property when the FDT_REG_SUPERNODES flag is given will force its
 * containing node to be included since it is not valid to have a property
 * that is not in a node.
 *
 * Using the information provided, the inclusion of a node can be controlled
 * either by a node name or its compatible string, or any other property
 * that the function can determine.
 *
 * As an example, including node "/" means to include the root node and all
 * root properties. A flag provides a way of also including supernodes (of
 * which there is none for the root node), and another flag includes
 * immediate subnodes, so in this case we would get the FDT_BEGIN_NODE and
 * FDT_END_NODE of all subnodes of /.
 *
 * The subnode feature helps in a hashing situation since it prevents the
 * root node from changing at all. Any change to non-excluded properties,
 * names of subnodes or number of subnodes would be detected.
 *
 * When used with FITs this provides the ability to hash and sign parts of
 * the FIT based on different configurations in the FIT. Then it is
 * impossible to change anything about that configuration (include images
 * attached to the configuration), but it may be possible to add new
 * configurations, new images or new signatures within the existing
 * framework.
 *
 * Adding new properties to a device tree may result in the string table
 * being extended (if the new property names are different from those
 * already added). This function can optionally include a region for
 * the string table so that this can be part of the hash too. This is always
 * the last region.
 *
 * The FDT also has a mem_rsvmap table which can also be included, and is
 * always the first region if so.
 *
 * The device tree header is not included in the region list. Since the
 * contents of the FDT are changing (shrinking, often), the caller will need
 * to regenerate the header anyway.
 *
 * @fdt:        Device tree to check
 * @h_include:  Function to call to determine whether to include a part or
 *              not:
 *
 *              @priv: Private pointer as passed to fdt_find_regions()
 *              @fdt: Pointer to FDT blob
 *              @offset: Offset of this node / property
 *              @type: Type of this part, FDT_IS_...
 *              @data: Pointer to data (node name, property name, compatible
 *                      string, value (not yet supported)
 *              @size: Size of data, or 0 if none
 *              @return 0 to exclude, 1 to include, -1 if no information is
 *              available
 * @priv:       Private pointer passed to h_include
 * @region:     Returns list of regions, sorted by offset
 * @max_regions: Maximum length of region list
 * @path:       Pointer to a temporary string for the function to use for
 *              building path names
 * @path_len:   Length of path, must be large enough to hold the longest
 *              path in the tree
 * @flags:      Various flags that control the region algortihm, see
 *              FDT_REG_...
 * @return number of regions in list. If this is >max_regions then the
 * region array was exhausted. You should increase max_regions and try
 * the call again. Only the first max_regions elements are available in the
 * array.
 *
 * On error a -ve value is return, which can be:
 *
 *      -FDT_ERR_BADSTRUCTURE (too deep or more END tags than BEGIN tags
 *      -FDT_ERR_BADLAYOUT
 *      -FDT_ERR_NOSPACE (path area is too small)
 */
int fdt_first_region(const void *fdt,
                int (*h_include)(void *priv, const void *fdt, int offset,
                                 int type, const char *data, int size),
                void *priv, struct fdt_region *region,
                char *path, int path_len, int flags,
                struct fdt_region_state *info);

/** fdt_next_region() - find next region
 *
 * See fdt_first_region() for full description. This function finds the
 * next region according to the provided parameters, which must be the same
 * as passed to fdt_first_region().
 *
 * This function can additionally return -FDT_ERR_NOTFOUND when there are no
 * more regions
 */
int fdt_next_region(const void *fdt,
                int (*h_include)(void *priv, const void *fdt, int offset,
                                 int type, const char *data, int size),
                void *priv, struct fdt_region *region,
                char *path, int path_len, int flags,
                struct fdt_region_state *info);

/**
 * fdt_add_alias_regions() - find aliases that point to existing regions
 *
 * Once a device tree grep is complete some of the nodes will be present
 * and some will have been dropped. This function checks all the alias nodes
 * to figure out which points point to nodes which are still present. These
 * aliases need to be kept, along with the nodes they reference.
 *
 * Given a list of regions function finds the aliases that still apply and
 * adds more regions to the list for these. This function is called after
 * fdt_next_region() has finished returning regions and requires the same
 * state.
 *
 * @fdt:        Device tree file to reference
 * @region:     List of regions that will be kept
 * @count:      Number of regions
 * @max_regions: Number of entries that can fit in @region
 * @info:       Region state as returned from fdt_next_region()
 * @return new number of regions in @region (i.e. count + the number added)
 * or -FDT_ERR_NOSPACE if there was not enough space.
 */
int fdt_add_alias_regions(const void *fdt, struct fdt_region *region, int count,
                          int max_regions, struct fdt_region_state *info);

#endif /* _LIBFDT_H */