fdt: Add a function to decode a variable-sized u32 array

Sometimes an array can be of variable size up to a maximum. Add a helper
function to decode this.

Signed-off-by: Simon Glass <sjg@chromium.org>

include/fdtdec.h

@@ -444,6 +444,22 @@ int fdtdec_lookup_phandle(const void *blob, int node, const char *prop_name);
 int fdtdec_get_int_array(const void *blob, int node, const char *prop_name,
 		u32 *array, int count);
 
+/**
+ * Look up a property in a node and return its contents in an integer
+ * array of given length. The property must exist but may have less data that
+ * expected (4*count bytes). It may have more, but this will be ignored.
+ *
+ * @param blob		FDT blob
+ * @param node		node to examine
+ * @param prop_name	name of property to find
+ * @param array		array to fill with data
+ * @param count		number of array elements
+ * @return number of array elements if ok, or -FDT_ERR_NOTFOUND if the
+ *		property is not found
+ */
+int fdtdec_get_int_array_count(const void *blob, int node,
+			       const char *prop_name, u32 *array, int count);
+
 /**
  * Look up a property in a node and return a pointer to its contents as a
  * unsigned int array of given length. The property must have at least enough

lib/fdtdec.c

@@ -485,6 +485,26 @@ int fdtdec_get_int_array(const void *blob, int node, const char *prop_name,
 	return err;
 }
 
+int fdtdec_get_int_array_count(const void *blob, int node,
+			       const char *prop_name, u32 *array, int count)
+{
+	const u32 *cell;
+	int len, elems;
+	int i;
+
+	debug("%s: %s\n", __func__, prop_name);
+	cell = fdt_getprop(blob, node, prop_name, &len);
+	if (!cell)
+		return -FDT_ERR_NOTFOUND;
+	elems = len / sizeof(u32);
+	if (count > elems)
+		count = elems;
+	for (i = 0; i < count; i++)
+		array[i] = fdt32_to_cpu(cell[i]);
+
+	return count;
+}
+
 const u32 *fdtdec_locate_array(const void *blob, int node,
 			       const char *prop_name, int count)
 {