rockchip: board: puma_rk3399: derive ethaddr from cpuid

Generate a MAC address based on the cpuid available in the efuse
block: Use the first 6 byte of the cpuid's SHA256 hash and set the
locally administered bits. Also ensure that the multicast bit is
cleared.

The MAC address is only generated and set if there is no ethaddr
present in the saved environment.
Signed-off-by: NKlaus Goger <klaus.goger@theobroma-systems.com>
Signed-off-by: NPhilipp Tomsich <philipp.tomsich@theobroma-systems.com>
Reviewed-by: NSimon Glass <sjg@chromium.org>

board/theobroma-systems/puma_rk3399/puma-rk3399.c

@@ -68,6 +68,42 @@ out:
 	return 0;
 }
 
+static void setup_macaddr(void)
+{
+#if CONFIG_IS_ENABLED(CMD_NET)
+	int ret;
+	const char *cpuid = getenv("cpuid#");
+	u8 hash[SHA256_SUM_LEN];
+	int size = sizeof(hash);
+	u8 mac_addr[6];
+
+	/* Only generate a MAC address, if none is set in the environment */
+	if (getenv("ethaddr"))
+		return;
+
+	if (!cpuid) {
+		debug("%s: could not retrieve 'cpuid#'\n", __func__);
+		return;
+	}
+
+	ret = hash_block("sha256", (void *)cpuid, strlen(cpuid), hash, &size);
+	if (ret) {
+		debug("%s: failed to calculate SHA256\n", __func__);
+		return;
+	}
+
+	/* Copy 6 bytes of the hash to base the MAC address on */
+	memcpy(mac_addr, hash, 6);
+
+	/* Make this a valid MAC address and set it */
+	mac_addr[0] &= 0xfe;  /* clear multicast bit */
+	mac_addr[0] |= 0x02;  /* set local assignment bit (IEEE802) */
+	eth_setenv_enetaddr("ethaddr", mac_addr);
+#endif
+
+	return;
+}
+
 static void setup_serial(void)
 {
 #if CONFIG_IS_ENABLED(ROCKCHIP_EFUSE)
@@ -79,8 +115,9 @@ static void setup_serial(void)
 	u64 serialno;
 	char serialno_str[16];
 
-	/* the first misc device will be used */
-	ret = uclass_get_device(UCLASS_MISC, 0, &dev);
+	/* retrieve the device */
+	ret = uclass_get_device_by_driver(UCLASS_MISC,
+					  DM_GET_DRIVER(rockchip_efuse), &dev);
 	if (ret) {
 		debug("%s: could not find efuse device\n", __func__);
 		return;
@@ -123,6 +160,7 @@ static void setup_serial(void)
 int misc_init_r(void)
 {
 	setup_serial();
+	setup_macaddr();
 
 	return 0;
 }