[PATCH v3 2/2] wifi: mt76: support per-band MAC addresses from OF child nodes

[Daniel Golle <daniel@makrotopia.org>]

With dual-band-dual-congruent front-ends which appear as two independent
radios it is desirable to assign a per-band MAC address from device-tree,
eg. using nvmem-cells.
Support specifying MAC-address related properties in band-specific child
nodes, e.g.
        wifi@0,0 {
                reg = <0x0000 0 0 0 0>;
                #addr-cells = <1>;
                #size-cells = <0>;

                band@0 {
                        /* 2.4 GHz */
                        reg = <0>;
                        nvmem-cells = <&macaddr 2>;
                        nvmem-cell-names = "mac-address";
                };

                band@1 {
                        /* 5 GHz */
                        reg = <1>;
                        nvmem-cells = <&macaddr 3>;
                        nvmem-cell-names = "mac-address";
                };
        };

Signed-off-by: Daniel Golle <daniel@makrotopia.org>
Tested-by: Shiji Yang <yangshiji66@outlook.com>
---
Changes since v2:
 * none

Changes since v1:
 * refactor and add missing of_node_put()

 drivers/net/wireless/mediatek/mt76/eeprom.c | 20 ++++++++++++++++++--
 1 file changed, 18 insertions(+), 2 deletions(-)

diff --git a/drivers/net/wireless/mediatek/mt76/eeprom.c b/drivers/net/wireless/mediatek/mt76/eeprom.c
index 36564930aef12..c2b3386cada1c 100644
--- a/drivers/net/wireless/mediatek/mt76/eeprom.c
+++ b/drivers/net/wireless/mediatek/mt76/eeprom.c
@@ -161,9 +161,25 @@ void
 mt76_eeprom_override(struct mt76_phy *phy)
 {
 	struct mt76_dev *dev = phy->dev;
-	struct device_node *np = dev->dev->of_node;
+	struct device_node *np = dev->dev->of_node, *band_np;
+	bool found_mac = false;
+	u32 reg;
+	int ret;
+
+	for_each_child_of_node(np, band_np) {
+		ret = of_property_read_u32(band_np, "reg", &reg);
+		if (ret)
+			continue;
+
+		if (reg == phy->band_idx) {
+			found_mac = !of_get_mac_address(band_np, phy->macaddr);
+			of_node_put(band_np);
+			break;
+		}
+	}
 
-	of_get_mac_address(np, phy->macaddr);
+	if (!found_mac)
+		of_get_mac_address(np, phy->macaddr);
 
 	if (!is_valid_ether_addr(phy->macaddr)) {
 		eth_random_addr(phy->macaddr);
-- 
2.41.0