drivers: ethernet: Add Helper function to load MAC address

Given an ethernet MAC configuration struct, load a MAC address into a
provided array.

Signed-off-by: Pieter De Gendt <[email protected]>

Author: pdgendt

drivers/ethernet/eth.h

@@ -8,6 +8,7 @@
 #define ZEPHYR_DRIVERS_ETHERNET_ETH_H_
 
 #include <zephyr/types.h>
+#include <zephyr/net/ethernet.h>
 #include <zephyr/random/random.h>
 
 /* helper macro to return mac address octet from local_mac_address prop */
@@ -42,4 +43,37 @@ static inline void gen_random_mac(uint8_t *mac_addr, uint8_t b0, uint8_t b1, uin
 	sys_rand_get(&mac_addr[3], 3U);
 }
 
+static inline int net_eth_mac_load(const struct net_eth_mac_config *cfg, uint8_t *mac_addr)
+{
+	if (cfg == NULL || cfg->type == NET_ETH_MAC_DEFAULT) {
+		return -ENODATA;
+	}
+
+	/* Copy the static part */
+	memcpy(mac_addr, cfg->addr, cfg->addr_len);
+
+	if (cfg->type == NET_ETH_MAC_STATIC && cfg->addr_len == NET_ETH_ADDR_LEN) {
+		/* Complete static address */
+		return 0;
+	}
+
+	if (cfg->type == NET_ETH_MAC_RANDOM) {
+		sys_rand_get(&mac_addr[cfg->addr_len], NET_ETH_ADDR_LEN - cfg->addr_len);
+
+		/* Set MAC address locally administered, unicast (LAA) */
+		mac_addr[0] |= 0x02;
+
+		return 0;
+	}
+
+#if defined(CONFIG_NVMEM)
+	if (cfg->type == NET_ETH_MAC_NVMEM) {
+		return nvmem_cell_read(&cfg->cell, &mac_addr[cfg->addr_len], 0,
+				       NET_ETH_ADDR_LEN - cfg->addr_len);
+	}
+#endif
+
+	return -ENODATA;
+}
+
 #endif /* ZEPHYR_DRIVERS_ETHERNET_ETH_H_ */