From 90f54b0e72580787ed78dbde1428411109b9abdb Mon Sep 17 00:00:00 2001 From: David Gibson Date: Fri, 24 Feb 2017 11:12:50 +1100 Subject: libfdt: Add fdt_setprop_empty() Device trees can contain empty (zero length) properties, which are often used as boolean flags. These can already be created using fdt_setprop() passing a length of zero and a pointer which is ignored. It is safe to pass NULL, but that may not be obvious from the interface. To make it clearer, add an fdt_setprop_empty() helper macro. Signed-off-by: David Gibson --- cpukit/include/libfdt.h | 30 ++++++++++++++++++++++++++++++ 1 file changed, 30 insertions(+) diff --git a/cpukit/include/libfdt.h b/cpukit/include/libfdt.h index c69e918899..ac42e04595 100644 --- a/cpukit/include/libfdt.h +++ b/cpukit/include/libfdt.h @@ -1527,6 +1527,36 @@ static inline int fdt_setprop_cell(void *fdt, int nodeoffset, const char *name, #define fdt_setprop_string(fdt, nodeoffset, name, str) \ fdt_setprop((fdt), (nodeoffset), (name), (str), strlen(str)+1) + +/** + * fdt_setprop_empty - set a property to an empty value + * @fdt: pointer to the device tree blob + * @nodeoffset: offset of the node whose property to change + * @name: name of the property to change + * + * fdt_setprop_empty() sets the value of the named property in the + * given node to an empty (zero length) value, or creates a new empty + * 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 + */ +#define fdt_setprop_empty(fdt, nodeoffset, name) \ + fdt_setprop((fdt), (nodeoffset), (name), NULL, 0) + /** * fdt_appendprop - append to or create a property * @fdt: pointer to the device tree blob -- cgit v1.2.3