Introduce function fdt_get_max_phandle(), which returns the largest value
of all phandles in a device tree. This is useful for allocating a new phandle
property, since all phandles must be unique.
Signed-off-by: Timur Tabi <ti...@freescale.com>
---
include/libfdt.h | 20 ++++++++++++++++++++
lib/libfdt/fdt_ro.c | 17 +++++++++++++++++
2 files changed, 37 insertions(+), 0 deletions(-)
diff --git a/include/libfdt.h b/include/libfdt.h
index d23d40e..62c4e5b 100644
--- a/include/libfdt.h
+++ b/include/libfdt.h
@@ -833,6 +833,26 @@ int fdt_nop_property(void *fdt, int nodeoffset, const char
*name);
*/
int fdt_nop_node(void *fdt, int nodeoffset);
+/**
+ * fdt_get_max_phandle - return the largest value of all phandles in the fdt
+ * @fdt: pointer to the device tree blob
+ *
+ * fdt_get_max_phandle() returns the largest value of all phandles.
+ *
+ * phandles are generally numbered sequentially from 1. To allow U-Boot to
+ * create a new phandle property, the value of that phandle must be unique.
+ * The safest way to do that is to determine the largest value among all
+ * phandles, and set the new phandle to that value plus one.
+ *
+ * returns:
+ * 0, there are no phandles in the fdt
+ * >0, the largest value of the phandles
+ * -FDT_ERR_BADMAGIC,
+ * -FDT_ERR_BADVERSION,
+ * -FDT_ERR_BADSTATE, standard meanings
+ */
+int fdt_get_max_phandle(const void *fdt);
+
/**********************************************************************/
/* Sequential write functions */
/**********************************************************************/
diff --git a/lib/libfdt/fdt_ro.c b/lib/libfdt/fdt_ro.c
index 1e1e322..4a4a84b 100644
--- a/lib/libfdt/fdt_ro.c
+++ b/lib/libfdt/fdt_ro.c
@@ -504,3 +504,20 @@ int fdt_node_offset_by_compatible(const void *fdt, int
startoffset,
return offset; /* error from fdt_next_node() */
}
+
+int fdt_get_max_phandle(const void *fdt)
+{
+ int offset;
+ uint32_t temp, phandle = 0;
+
+ FDT_CHECK_HEADER(fdt);
+
+ for (offset = fdt_next_node(fdt, -1, NULL); offset >= 0;
+ offset = fdt_next_node(fdt, offset, NULL)) {
+ temp = fdt_get_phandle(fdt, offset);
+ if (temp > phandle)
+ phandle = temp;
+ }
+
+ return phandle;
+}
--
1.6.5
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