fdtdec: Add fdtdec_set_ethernet_mac_address()

This function can be used to set the local MAC address for the default
Ethernet interface in its device tree node. The default interface is
identified by the "ethernet" alias.

One case where this is useful is for devices that store their MAC
address in a custom location. Once extracted, board code can store the
MAC address in U-Boot's control DTB so that it will automatically be
used by the Ethernet uclass.

Signed-off-by: Thierry Reding <treding@nvidia.com>
Signed-off-by: Tom Warren <twarren@nvidia.com>

1 files changed, 29 insertions, 0 deletions

diff --git a/lib/fdtdec.c b/lib/fdtdec.c
index d0ba888973..3ee786b579 100644
--- a/lib/fdtdec.c
+++ b/lib/fdtdec.c
@@ -1261,6 +1261,35 @@ __weak void *board_fdt_blob_setup(void)
 }
 #endif
 
+int fdtdec_set_ethernet_mac_address(void *fdt, const u8 *mac, size_t size)
+{
+	const char *path;
+	int offset, err;
+
+	if (!is_valid_ethaddr(mac))
+		return -EINVAL;
+
+	path = fdt_get_alias(fdt, "ethernet");
+	if (!path)
+		return 0;
+
+	debug("ethernet alias found: %s\n", path);
+
+	offset = fdt_path_offset(fdt, path);
+	if (offset < 0) {
+		debug("ethernet alias points to absent node %s\n", path);
+		return -ENOENT;
+	}
+
+	err = fdt_setprop_inplace(fdt, offset, "local-mac-address", mac, size);
+	if (err < 0)
+		return err;
+
+	debug("MAC address: %pM\n", mac);
+
+	return 0;
+}
+
 static int fdtdec_init_reserved_memory(void *blob)
 {
 	int na, ns, node, err;