device_tree: Make FDT property data non-const

FDT property data should not be const -- sometimes we need to update it,
for example when fixing up phandles in an overlay. On the other hand
it's occasionally desirable to put a string constant in there without
having to strdup() it all the time... let's just live with the tiny
implicit assumption that the data we'd want to modify (phandle
references, mostly) will never be added from string constants, and put a
cast in dt_add_string_prop().

Change-Id: Ifac103fcff0520cc427ab9a2aa141c65e12507ac
Signed-off-by: Julius Werner <jwerner@chromium.org>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/32868
Reviewed-by: Hung-Te Lin <hungte@chromium.org>
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>

src/include/device_tree.h

@@ -52,7 +52,7 @@ struct fdt_header {
 struct fdt_property
 {
 	const char *name;
-	const void *data;
+	void *data;
 	uint32_t size;
 };
 
@@ -165,7 +165,7 @@ void dt_write_int(u8 *dest, u64 src, size_t length);
 void dt_delete_prop(struct device_tree_node *node, const char *name);
 // Add different kinds of properties to a node, or update existing ones.
 void dt_add_bin_prop(struct device_tree_node *node, const char *name,
-		     const void *data, size_t size);
+		     void *data, size_t size);
 void dt_add_string_prop(struct device_tree_node *node, const char *name,
 			const char *str);
 void dt_add_u32_prop(struct device_tree_node *node, const char *name, u32 val);

src/lib/device_tree.c

@@ -883,7 +883,7 @@ void dt_delete_prop(struct device_tree_node *node, const char *name)
  * @param size		The size of data in bytes.
  */
 void dt_add_bin_prop(struct device_tree_node *node, const char *name,
-		     const void *data, size_t size)
+		     void *data, size_t size)
 {
 	struct device_tree_property *prop;
 
@@ -955,7 +955,7 @@ void dt_find_bin_prop(const struct device_tree_node *node, const char *name,
 void dt_add_string_prop(struct device_tree_node *node, const char *name,
 			const char *str)
 {
-	dt_add_bin_prop(node, name, str, strlen(str) + 1);
+	dt_add_bin_prop(node, name, (char *)str, strlen(str) + 1);
 }
 
 /*

src/soc/cavium/cn81xx/soc.c

@@ -149,7 +149,7 @@ static void dt_platform_fixup_mac(struct device_tree_node *node)
 		if (*localmac)
 			return;
 		if (used_mac < num_free_mac_addresses) {
-			const u64 genmac = next_free_mac_address + used_mac;
+			u64 genmac = next_free_mac_address + used_mac;
 			dt_add_bin_prop(node, name, &genmac, 6);
 			used_mac++;
 			return;