Introduce fdtw_read_array() helper

fdtw_read_cells() can only read one or two cells, sometimes it may be
needed to read more cells from one property.

Change-Id: Ie70dc76d1540cd6a04787cde7cccb4d1bafc7282
Signed-off-by: Antonio Nino Diaz <antonio.ninodiaz@arm.com>

common/fdt_wrappers.c

@@ -40,7 +40,6 @@ int fdtw_read_cells(const void *dtb, int node, const char *prop,
 		return -1;
 	}
 
-
 	/* Verify that property length accords with cell length */
 	if (NCELLS((unsigned int)value_len) != cells) {
 		WARN("Property length mismatch\n");
@@ -62,6 +61,45 @@ int fdtw_read_cells(const void *dtb, int node, const char *prop,
 	return 0;
 }
 
+/*
+ * Read cells from a given property of the given node. Any number of 32-bit
+ * cells of the property can be read. The fdt pointer is updated. Returns 0 on
+ * success, and -1 on error.
+ */
+int fdtw_read_array(const void *dtb, int node, const char *prop,
+		unsigned int cells, void *value)
+{
+	const uint32_t *value_ptr;
+	int value_len;
+
+	assert(dtb != NULL);
+	assert(prop != NULL);
+	assert(value != NULL);
+	assert(node >= 0);
+
+	/* Access property and obtain its length (in bytes) */
+	value_ptr = fdt_getprop_namelen(dtb, node, prop, (int)strlen(prop),
+			&value_len);
+	if (value_ptr == NULL) {
+		WARN("Couldn't find property %s in dtb\n", prop);
+		return -1;
+	}
+
+	/* Verify that property length accords with cell length */
+	if (NCELLS((unsigned int)value_len) != cells) {
+		WARN("Property length mismatch\n");
+		return -1;
+	}
+
+	uint32_t *dst = value;
+
+	for (unsigned int i = 0U; i < cells; i++) {
+		dst[i] = fdt32_to_cpu(value_ptr[i]);
+	}
+
+	return 0;
+}
+
 /*
  * Read string from a given property of the given node. Up to 'size - 1'
  * characters are read, and a NUL terminator is added. Returns 0 on success,

include/common/fdt_wrappers.h

@@ -14,6 +14,8 @@
 
 int fdtw_read_cells(const void *dtb, int node, const char *prop,
 		unsigned int cells, void *value);
+int fdtw_read_array(const void *dtb, int node, const char *prop,
+		unsigned int cells, void *value);
 int fdtw_read_string(const void *dtb, int node, const char *prop,
 		char *str, size_t size);
 int fdtw_write_inplace_cells(void *dtb, int node, const char *prop,