libfdt: Add max phandle retrieval function
Add a function to retrieve the highest phandle in a given device tree.
Acked-by: Simon Glass <sjg@chromium.org>
Reviewed-by: Stefan Agner <stefan@agner.ch>
Reviewed-by: David Gibson <david@gibson.dropbear.id.au>
Signed-off-by: Maxime Ripard <maxime.ripard@free-electrons.com>
Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
diff --git a/libfdt/fdt_ro.c b/libfdt/fdt_ro.c
index 50cce86..0459098 100644
--- a/libfdt/fdt_ro.c
+++ b/libfdt/fdt_ro.c
@@ -88,6 +88,32 @@
return (strlen(p) == len) && (memcmp(p, s, len) == 0);
}
+uint32_t fdt_get_max_phandle(const void *fdt)
+{
+ uint32_t max_phandle = 0;
+ int offset;
+
+ for (offset = fdt_next_node(fdt, -1, NULL);;
+ offset = fdt_next_node(fdt, offset, NULL)) {
+ uint32_t phandle;
+
+ if (offset == -FDT_ERR_NOTFOUND)
+ return max_phandle;
+
+ if (offset < 0)
+ return (uint32_t)-1;
+
+ phandle = fdt_get_phandle(fdt, offset);
+ if (phandle == (uint32_t)-1)
+ continue;
+
+ if (phandle > max_phandle)
+ max_phandle = phandle;
+ }
+
+ return 0;
+}
+
int fdt_get_mem_rsv(const void *fdt, int n, uint64_t *address, uint64_t *size)
{
FDT_CHECK_HEADER(fdt);
diff --git a/libfdt/libfdt.h b/libfdt/libfdt.h
index be109a8..06b84cc 100644
--- a/libfdt/libfdt.h
+++ b/libfdt/libfdt.h
@@ -287,6 +287,21 @@
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. This will ignore badly formatted phandles, or phandles
+ * with a value of 0 or -1.
+ *
+ * returns:
+ * the highest phandle on success
+ * 0, if no phandle was found in the device tree
+ * -1, 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
*
diff --git a/tests/get_phandle.c b/tests/get_phandle.c
index 2079591..22bd7b8 100644
--- a/tests/get_phandle.c
+++ b/tests/get_phandle.c
@@ -44,6 +44,7 @@
int main(int argc, char *argv[])
{
+ uint32_t max;
void *fdt;
test_init(argc, argv);
@@ -53,5 +54,10 @@
check_phandle(fdt, "/subnode@2", PHANDLE_1);
check_phandle(fdt, "/subnode@2/subsubnode@0", PHANDLE_2);
+ max = fdt_get_max_phandle(fdt);
+ if (max != PHANDLE_2)
+ FAIL("fdt_get_max_phandle returned 0x%x instead of 0x%x\n",
+ max, PHANDLE_2);
+
PASS();
}
