From d1c6314887c4d6712f7bd9ba7428b6517e7732e0 Mon Sep 17 00:00:00 2001 From: David Gibson Date: Tue, 9 Mar 2010 17:39:14 +1100 Subject: libfdt: Implement property iteration functions For ages, we've been talking about adding functions to libfdt to allow iteration through properties. So, finally, here are some. I got bogged down on this for a long time because I didn't want to expose offsets directly to properties to the callers. But without that, attempting to make reasonable iteration functions just became horrible. So eventually, I settled on an interface which does now expose property offsets. fdt_first_property_offset() and fdt_next_property_offset() are used to step through the offsets of the properties starting from a particularly node offset. The details of the property at each offset can then be retrieved with either fdt_get_property_by_offset() or fdt_getprop_by_offset() which have interfaces similar to fdt_get_property() and fdt_getprop() respectively. No explicit testcases are included, but we do use the new functions to reimplement the existing fdt_get_property() function. Signed-off-by: David Gibson This was extracted from the DTC commit: 73dca9ae0b9abe6924ba640164ecce9f8df69c5a Mon Sep 17 00:00:00 2001 Signed-off-by: Gerald Van Baren --- include/libfdt.h | 103 +++++++++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 103 insertions(+) (limited to 'include/libfdt.h') diff --git a/include/libfdt.h b/include/libfdt.h index d23d40e07b..de82ed5ffd 100644 --- a/include/libfdt.h +++ b/include/libfdt.h @@ -342,6 +342,75 @@ int fdt_path_offset(const void *fdt, const char *path); */ 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_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 @@ -395,6 +464,40 @@ static inline struct fdt_property *fdt_get_property_w(void *fdt, int nodeoffset, 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 -- cgit v1.2.3