[U-Boot] [PATCH 02/23] fdt: Add a function to get the index of a string

[Thierry Reding <thierry.reding@gmail.com>]

From: Thierry Reding <treding@nvidia.com>

Given a device tree node and a property name, the fdt_get_string_index()
function will look up a given string in the string list contained in the
property's value and return its index.

Signed-off-by: Thierry Reding <treding@nvidia.com>
---
 include/libfdt.h    | 11 +++++++++++
 lib/libfdt/fdt_ro.c | 28 ++++++++++++++++++++++++++++
 2 files changed, 39 insertions(+)

diff --git a/include/libfdt.h b/include/libfdt.h
index e7f991b388cf..4d7fb2681669 100644
--- a/include/libfdt.h
+++ b/include/libfdt.h
@@ -857,6 +857,17 @@ int fdt_node_offset_by_compatible(const void *fdt, int startoffset,
  */
 int fdt_stringlist_contains(const char *strlist, int listlen, const char *str);
 
+/**
+ * fdt_get_string_index - get the index of a string in a string list
+ * @fdt: pointer to the device tree blob
+ * @node: offset of the node
+ * @property: name of the property containing the string list
+ * @string: string to look up in the string list
+ * @return the index of the string or negative on error
+ */
+int fdt_get_string_index(const void *fdt, int node, const char *property,
+			 const char *string);
+
 /**********************************************************************/
 /* Read-only functions (addressing related)                           */
 /**********************************************************************/
diff --git a/lib/libfdt/fdt_ro.c b/lib/libfdt/fdt_ro.c
index 17cd11333c1e..f211c64ca7ca 100644
--- a/lib/libfdt/fdt_ro.c
+++ b/lib/libfdt/fdt_ro.c
@@ -14,6 +14,8 @@
 
 #include "libfdt_internal.h"
 
+#define max(x, y) (((x) < (y)) ? (y) : (x))
+
 static int _fdt_nodename_eq(const void *fdt, int offset,
 			    const char *s, int len)
 {
@@ -491,6 +493,32 @@ int fdt_stringlist_contains(const char *strlist, int listlen, const char *str)
 	return 0;
 }
 
+int fdt_get_string_index(const void *fdt, int node, const char *property,
+			 const char *string)
+{
+	const char *list, *end;
+	int len, index = 0;
+
+	list = fdt_getprop(fdt, node, property, &len);
+	if (!list)
+		return len;
+
+	end = list + len;
+
+	while (list < end) {
+		int n = strlen(string);
+		int m = strlen(list);
+
+		if (n == m && memcmp(list, string, n) == 0)
+			return index;
+
+		list += max(n, m) + 1;
+		index++;
+	}
+
+	return -FDT_ERR_NOTFOUND;
+}
+
 int fdt_node_check_compatible(const void *fdt, int nodeoffset,
 			      const char *compatible)
 {
-- 
2.0.4