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Diffstat (limited to 'cpukit/include/rtems/rtems-fdt.h')
| -rw-r--r-- | cpukit/include/rtems/rtems-fdt.h | 621 |
1 files changed, 621 insertions, 0 deletions
diff --git a/cpukit/include/rtems/rtems-fdt.h b/cpukit/include/rtems/rtems-fdt.h new file mode 100644 index 0000000000..ebc222e4c9 --- /dev/null +++ b/cpukit/include/rtems/rtems-fdt.h @@ -0,0 +1,621 @@ +/* + * COPYRIGHT (c) 2013-2017 Chris Johns <chrisj@rtems.org> + * + * The license and distribution terms for this file may be + * found in the file LICENSE in this distribution or at + * http://www.rtems.org/license/LICENSE. + * + * Interface based on the libdft: + * libfdt - Flat Device Tree manipulation + * Copyright (C) 2006 David Gibson, IBM Corporation. + */ +/** + * @file + * + * @ingroup rtems_fdt + * + * @brief RTEMS Flattened Device Tree + * + * Support for loading, managing and accessing FDT blobs in RTEMS. + */ + +#if !defined (_RTEMS_FDT_H_) +#define _RTEMS_FDT_H_ + +#include <rtems.h> +#include <rtems/chain.h> + +#ifdef __cplusplus +extern "C" { +#endif /* __cplusplus */ + +/** + * A blob. + */ +struct rtems_fdt_blob; +typedef struct rtems_fdt_blob rtems_fdt_blob; + +/** + * A blob handle is a way to manage access to the FDT blobs. The blob is + * referenced via the handle to allow searches across loaded DTB's to return + * the referenced DTB. + */ +typedef struct +{ + rtems_fdt_blob* blob; /**< The blob the handle references. */ +} rtems_fdt_handle; + +/* + * The following are mappings to the standard FDT calls. + */ + +/** + * RTEMS_FDT_ERR_NOTFOUND: The requested node or property does not exist + */ +#define RTEMS_FDT_ERR_NOTFOUND 1 +/** + * RTEMS_FDT_ERR_EXISTS: Attemped to create a node or property which already + * exists */ +#define RTEMS_FDT_ERR_EXISTS 2 +/** + * RTEMS_FDT_ERR_NOSPACE: Operation needed to expand the device tree, but its + * buffer did not have sufficient space to contain the expanded tree. Use + * rtems_fdt_open_into() to move the device tree to a buffer with more space. + */ +#define RTEMS_FDT_ERR_NOSPACE 3 + +/* Error codes: codes for bad parameters */ +/** + * RTEMS_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 RTEMS_FDT_ERR_BADOFFSET 4 +/** + * RTEMS_FDT_ERR_BADPATH: Function was passed a badly formatted path + * (e.g. missing a leading / for a function which requires an absolute path) +*/ +#define RTEMS_FDT_ERR_BADPATH 5 +/** + * RTEMS_FDT_ERR_BADPHANDLE: Function was passed an invalid phandle value. + * phandle values of 0 and -1 are not permitted. + */ +#define RTEMS_FDT_ERR_BADPHANDLE 6 +/** + * RTEMS_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. + */ +#define RTEMS_FDT_ERR_BADSTATE 7 + +/* Error codes: codes for bad device tree blobs */ + +/** + * RTEMS_FDT_ERR_TRUNCATED: Structure block of the given device tree ends + * without an RTEMS_FDT_END tag. + */ +#define RTEMS_FDT_ERR_TRUNCATED 8 +/** + * RTEMS_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 RTEMS_FDT_ERR_BADMAGIC 9 +/** RTEMS_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 rtems_fdt_open_into() is required to convert the tree to the expected + * version. + */ +#define RTEMS_FDT_ERR_BADVERSION 10 +/** + * RTEMS_FDT_ERR_BADSTRUCTURE: Given device tree has a corrupt structure block + * or other serious error (e.g. misnested nodes, or subnodes preceding + * properties). + */ +#define RTEMS_FDT_ERR_BADSTRUCTURE 11 +/** + * RTEMS_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 rtems_fdt_open_into() to reorganize + * the tree into a form suitable for the read-write operations. + */ +#define RTEMS_FDT_ERR_BADLAYOUT 12 +/** + * "Can't happen" error indicating a bug in libfdt + */ +#define RTEMS_FDT_ERR_INTERNAL 13 + +/* RTEMS error codes. */ + +/** + * Invalid handle. + */ +#define RTEMS_FDT_ERR_INVALID_HANDLE 100 +/** + * No memory. + */ +#define RTEMS_FDT_ERR_NO_MEMORY 101 +/** + * File not found. + */ +#define RTEMS_FDT_ERR_NOT_FOUND 102 +/** + * Cannot read the DTB into memory. + */ +#define RTEMS_FDT_ERR_READ_FAIL 103 +/** + * The blob cannot be unloaded as it is referenced. + */ +#define RTEMS_FDT_ERR_REFERENCED 104 + +#define RTEMS_FDT_ERR_RTEMS_MIN 100 +#define RTEMS_FDT_ERR_MAX 104 + +/** + * Initialise a handle to a default state. + * + * @param handle The handle to initialise. + */ +void rtems_fdt_init_handle (rtems_fdt_handle* handle); + +/** + * Duplicate a handle. The copy must be released. + * + * @param from Duplicate from this handle. + * @param to Duplicate to this handle. + */ +void rtems_fdt_dup_handle (rtems_fdt_handle* from, rtems_fdt_handle* to); + +/** + * Release a blob from a handle and clear it. + * + * @param handle The handle to check. + */ +void rtems_fdt_release_handle (rtems_fdt_handle* handle); + +/** + * Check if a handle had a valid blob assigned. + * + * @param handle The handle to check. + * @retval true The handle has a valid blob. + * @retval false The handle does not have a valid blob. + */ +bool rtems_fdt_valid_handle (const rtems_fdt_handle* handle); + +/** + * Find a tree node by its full path looking across of loaded blobs.. 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). + * + * If the handle points to a valid blob it is release and the search starts + * from the first blob. + * + * @param handle The FDT handle assigned to the blob if found else left invalid. + * @param path Full path of the node to locate. + * @param int If less than 0 an error code else the node offset is returned. + */ +int rtems_fdt_find_path_offset (rtems_fdt_handle* handle, const char* path); + +/** + * Load a device tree blob or DTB file into memory and register it on the chain + * of blobs. + * + * @param filename The name of the blob file to load. + * @param handle The handle returns the reference to the blob once load. + * @return int If less than 0 it is an error code else it is the blob descriptor. + */ +int rtems_fdt_load (const char* const filename, rtems_fdt_handle* handle); + +/** + * Register a device tree blob or DTB on to the chain of blobs. + * + * @param blob_desc A pointer to the blob. + * @param handle The handle returns the reference to the blob once load. + * @return int If less than 0 it is an error code else it is the blob descriptor. + */ +int rtems_fdt_register (const void* blob, rtems_fdt_handle* handle); + +/** + * Unload a device tree blob or DTB file and release any memory allocated when + * loading. The blob is removed from the list of registered. + * + * @param blob_desc A valid blob descriptor. + * @return int If less than 0 it is an error code else 0 is return on success. + */ +int rtems_fdt_unload (rtems_fdt_handle* handle); + +/** + * 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. + * + * @param blob_desc A valid blob descriptor. + * @return int The number of entries. + */ +int rtems_fdt_num_mem_rsv (rtems_fdt_handle* handle); + +/** + * Retrieve one memory reserve map entry. 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. + * + * @param blob_desc A valid blob descriptor. + * @param address Pointer to 64-bit variables to hold the addresses. + * @param size Pointer to 64-bit variables to hold the size. + * @return int If less than 0 it is an error code else 0 is returned on + * success. + */ +int rtems_fdt_get_mem_rsv (rtems_fdt_handle* handle, + int n, + uint64_t* address, + uint64_t* size); + +/** + * Find a subnode based on substring. Identical to rtems_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. + * + * @param blob_desc A valid blob descriptor. + * @param arentoffset Structure block offset of a node + * @param name Name of the subnode to locate. + * @param namelen Number of characters of name to consider. + * @return int If less than 0 it is an error code else the node offset is + * returned. + */ +int rtems_fdt_subnode_offset_namelen (rtems_fdt_handle* handle, + int parentoffset, + const char* const name, + int namelen); + +/** + * Find a subnode of a given node at structure block offset parentoffset with + * the given name. The name may include a unit address, in which case + * rtems_fdt_subnode_offset() will find the subnode with that unit address, or + * the unit address may be omitted, in which case rtems_fdt_subnode_offset() + * will find an arbitrary subnode whose name excluding unit address matches the + * given name. + * + * @param blob_desc A valid blob descriptor. + * @param parentoffset Structure block offset of a node. + * @param name The name of the subnode to locate. + * @return int If less than 0 it is an error code else the subnode offset is + * returned. + */ +int rtems_fdt_subnode_offset (rtems_fdt_handle* handle, + int parentoffset, + const char* const name); + +/** + * Find a tree node by its full path. 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). + * + * @param handle The FDT handle to the current blob. + * @param path Full path of the node to locate. + * @param int If less than 0 an error code else the node offset is returned. + */ +int rtems_fdt_path_offset (rtems_fdt_handle* handle, const char* path); + +/** + * Retrieve the name of a given node (including unit address) of the device + * tree node at structure block offset @nodeoffset. If @length is non-NULL, + * the length of this name is also returned, in the integer pointed to by + * @length. + * + * @param handle The FDT handle to the current blob. + * @param nodeoffset Structure block offset of the starting node. + * @param length Pointer to an integer variable (will be overwritten) or NULL. + * @return const char* The node's name on success or NULL on error. The length + * if non-NULL will hold the error code. + */ +const char* rtems_fdt_get_name (rtems_fdt_handle* handle, + int nodeoffset, + int* length); + +/** + * Get property value based on substring. Identical to rtems_fdt_getprop(), but + * only examine the first namelen characters of name for matching the property + * name. + * + * @param handle The FDT handle to the current blob. + * @param nodeoffset Offset of the node whose property to find + * @param name The name of the property to find + * @param namelen The number of characters of name to consider + * @param length A pointer to an integer variable (will be overwritten) or + * NULL. + * @return const void* The node's property on success or NULL on error. The + * length if non-NULL will hold the error code. + */ +const void *rtems_fdt_getprop_namelen (rtems_fdt_handle* handle, + int nodeoffset, + const char* const name, + int namelen, + int* length); + +/** + * Retrieve the value of a given property. 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 @length. + * + * @param handle The FDT handle to the current blob. + * @param nodeoffset The offset of the node whose property to find. + * @param name The name of the property to find. + * @param length A pointer to an integer variable (will be overwritten) or + * NULL. + * @return const void* The node's property on success or NULL on error. The + * length if non-NULL will hold the error code. + */ +const void *rtems_fdt_getprop (rtems_fdt_handle* handle, + int nodeoffset, + const char* const name, + int* length); + +/** + * Retrieve the phandle of a given of the device tree node at structure block + * offset nodeoffset. + * + * @param handle The FDT handle to the current blob. + * @oaram nodeoffset The structure block offset of the node. + * return uint32_t The phandle of the node at nodeoffset, on success (!= 0, != + * -1) 0, if the node has no phandle, or another error occurs. + */ +uint32_t rtems_fdt_get_phandle (rtems_fdt_handle* handle, int nodeoffset); + +/** + * Get alias based on substring. Identical to rtems_fdt_get_alias(), but only + * examine the first namelen characters of name for matching the alias name. + * + * @param handle The FDT handle to the current blob. + * @param name The name of the alias th look up. + * @param namelen The number of characters of name to consider. + * @return const char* The alias or NULL. + */ +const char *rtems_fdt_get_alias_namelen (rtems_fdt_handle* handle, + const char* const name, + int namelen); + +/** + * Retreive the path referenced by a given alias. That is, the value of the + * property named 'name' in the node /aliases. + * + * @param handle The FDT handle to the current blob. + * @param name The name of the alias to look up. + * @return const char* A pointer to the expansion of the alias named 'name', of + * it exists NULL, if the given alias or the /aliases node + * does not exist + */ +const char* rtems_fdt_get_alias (rtems_fdt_handle* handle, const char* name); + +/** + * Determine the full path of a node. This function is expensive, as it must + * scan the device tree structure from the start to nodeoffset. It computes the + * full path of the node at offset nodeoffset, and records that path in the + * buffer at buf. + * + * @param handle The FDT handle to the current blob. + * @param nodeoffset The offset of the node whose path to find. + * @param buf A character buffer to contain the returned path (will be + * overwritten) + * @param buflen The size of the character buffer at buf. + * @return int 0 on success of an error code. + */ +int rtems_fdt_get_path (rtems_fdt_handle* handle, + int nodeoffset, + char* buf, + int buflen); + +/** + * Find a specific ancestor of a node at a specific depth from the root (where + * the root itself has depth 0, its immediate subnodes depth 1 and so forth). + * So rtems_fdt_supernode_atdepth_offset(blob, nodeoffset, 0, NULL); will + * always return 0, the offset of the root node. If the node at nodeoffset has + * depth D, then: + * rtems_fdt_supernode_atdepth_offset(blob, nodeoffset, D, NULL); + * will return nodeoffset itself. + * + * @param handle The FDT handle to the current blob. + * @param nodeoffset The offset of the node whose parent to find. + * @param supernodedepth The depth of the ancestor to find. + * @oaram nodedepth The pointer to an integer variable (will be overwritten) or + * NULL + * @return int If less than 0 an error else the node offset. + */ +int rtems_fdt_supernode_atdepth_offset (rtems_fdt_handle* handle, + int nodeoffset, + int supernodedepth, + int* nodedepth); + +/** + * Find 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. + * + * @param handle The FDT handle to the current blob. + * @param nodeoffset The offset of the node whose parent to find. + * @return int If less than 0 an error else the node offset. + */ +int rtems_fdt_node_depth (rtems_fdt_handle* handle, int nodeoffset); + +/** + * Find the parent of a given node. This funciton 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*. + * + * @param handle The FDT handle to the current blob. + * @param nodeoffset The offset of the node whose parent to find. + * @return int If less than 0 an error else the node offset. + */ +int rtems_fdt_parent_offset (rtems_fdt_handle* handle, int nodeoffset); + +/** + * Find nodes with a given property value. This funtion 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 = rtemsfdt_node_offset_by_prop_value(blob, -1, propname, + * propval, proplen); + * while (offset != -RTEMS_FDT_ERR_NOTFOUND) { + * // other code here + * offset = rtems_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. + * + * @param handle The FDT handle to the current blob. + * @param startoffset Only find nodes after this offset. + * @param propname The property name to check. + * @param propval The property value to search for. + * @param proplen The length of the value in propval. + * @return int The structure block offset of the located node (>= 0, + * >startoffset), on success and an error code is less + * than 0. + */ +int rtems_fdt_node_offset_by_prop_value (rtems_fdt_handle* handle, + int startoffset, + const char* const propname, + const void* propval, + int proplen); + +/** + * Find the node with a given phandle returning 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. + * + * @param handle The FDT handle to the current blob. + * @param phandle The phandle value. + * @return int If less than 0 an error else the node offset. + */ +int rtems_fdt_node_offset_by_phandle (rtems_fdt_handle* handle, + uint32_t phandle); + +/** + * Check a node's compatible property returning 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. + * + * @param handle The FDT handle to the current blob. + * @param nodeoffset The offset of a tree node. + * @param compatible The string to match against. + * @retval 0, if the node has a 'compatible' property listing the given string. + * @retval 1, if the node has a 'compatible' property, but it does not list the + * given string + */ +int rtems_fdt_node_check_compatible (rtems_fdt_handle* handle, + int nodeoffset, + const char* const compatible); + +/** + * Find nodes with a given 'compatible' value returning 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 = rtems_fdt_node_offset_by_compatible(blob, -1, compatible); + * while (offset != -RTEMS_FDT_ERR_NOTFOUND) { + * // other code here + * offset = rtems_fdt_node_offset_by_compatible(blob, 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. + * + * @param handle The FDT handle to the current blob. + * @param startoffset Only find nodes after this offset. + * @param compatible The 'compatible' string to match against. + * @return int If less than 0 an error else the node offset. + */ +int rtems_fdt_node_offset_by_compatible(rtems_fdt_handle* handle, + int startoffset, + const char* compatible); + +/** + * Traverse to the next node. + * + * @param handle The FDT handle to the current blob. + * @param offset The offset in the blob to start looking for the next node. + * @param depth Pointer to return the depth the node is. + * @return int If less than 0 an error else the node offset. + */ +int rtems_fdt_next_node (rtems_fdt_handle* handle, int offset, int* depth); + +/** + * Return an error string given an error value. + * + * @param errval The error value. + * @return const char* The error string. + */ +const char* rtems_fdt_strerror (int errval); + +/** + * Return a property given a path. + */ +int rtems_fdt_prop_value(const char* const path, + const char* const propname, + void* value, + size_t* size); + +/** + * Create a map given a path the property name and the names of the subnodes of + * the path. + */ +int rtems_fdt_prop_map (const char* const path, + const char* const propname, + const char* const names[], + uint32_t* values, + size_t count); + +/* + * Get a value given a path and a property. + */ +int rtems_fdt_get_value (const char* const path, + const char* const property, + size_t size, + uint32_t* value); + +/** + * Get the number of entries in an FDT handle. + */ +int rtems_fdt_num_entries(rtems_fdt_handle* handle); + +/** + * Get the numbered entry name. Note that the id isn't the same as + * the offset - it's numbered 0, 1, 2 ... num_entries-1 + */ +const char *rtems_fdt_entry_name(rtems_fdt_handle* handle, int id); + +/** + * Get the numbered entry offset. Note that the id isn't the same as + * the offset - it's numbered 0, 1, 2 ... num_entries-1 + */ +int rtems_fdt_entry_offset(rtems_fdt_handle* handle, int id); + +/* + * Helper function to convert the void* property result to a 32bit unsigned int. + */ +uint32_t rtems_fdt_get_uint32 (const void* prop); + +#ifdef __cplusplus +} +#endif /* __cplusplus */ + +#endif |