board: dhelectronics: Implement common MAC address functions

This is a starting point for unifying duplicate code in the DH board
files. The functions for setting up MAC addresses are very similar for
the i.MX6, i.MX8 and stm32mp1 based boards.

All pre-existing implementations follow the same logic:

(1) Check if ethaddr is already set in the environment
(2) If not, try to get it from a board specific location (e.g. fuse)
(3) If not, try to get it from eeprom

After this commit, (1) and (3) are implemented as common functions,
ready to be used by board specific files.

Furthermore there is an implementation of (2) for imx based boards.

Signed-off-by: Philip Oberfichtner <pro@denx.de>
Reviewed-by: Marek Vasut <marex@denx.de>

board/dhelectronics/common/Makefile

@@ -0,0 +1,10 @@
+# SPDX-License-Identifier: GPL-2.0+
+#
+# Copyright 2022 DENX Software Engineering GmbH, Philip Oberfichtner <pro@denx.de>
+#
+
+obj-y += dh_common.o
+
+ifneq (,$(CONFIG_ARCH_MX6)$(CONFIG_ARCH_IMX8M))
+obj-y += dh_imx.o
+endif

board/dhelectronics/common/dh_common.c

@@ -0,0 +1,65 @@
+// SPDX-License-Identifier: GPL-2.0+
+/*
+ * Copyright 2022 Marek Vasut <marex@denx.de>
+ * Copyright 2022 DENX Software Engineering GmbH, Philip Oberfichtner <pro@denx.de>
+ */
+
+#include <common.h>
+#include <dm.h>
+#include <i2c_eeprom.h>
+#include <net.h>
+
+#include "dh_common.h"
+
+bool dh_mac_is_in_env(const char *env)
+{
+	unsigned char enetaddr[6];
+
+	return eth_env_get_enetaddr(env, enetaddr);
+}
+
+int dh_get_mac_from_eeprom(unsigned char *enetaddr, const char *alias)
+{
+	struct udevice *dev;
+	int ret;
+	ofnode node;
+
+	node = ofnode_path(alias);
+	if (!ofnode_valid(node)) {
+		printf("%s: ofnode for %s not found!", __func__, alias);
+		return -ENOENT;
+	}
+
+	ret = uclass_get_device_by_ofnode(UCLASS_I2C_EEPROM, node, &dev);
+	if (ret) {
+		printf("%s: Cannot find EEPROM! ret = %d\n", __func__, ret);
+		return ret;
+	}
+
+	ret = i2c_eeprom_read(dev, 0xfa, enetaddr, 0x6);
+	if (ret) {
+		printf("%s: Error reading EEPROM! ret = %d\n", __func__, ret);
+		return ret;
+	}
+
+	if (!is_valid_ethaddr(enetaddr)) {
+		printf("%s: Address read from EEPROM is invalid!\n", __func__);
+		return -EINVAL;
+	}
+
+	return 0;
+}
+
+__weak int dh_setup_mac_address(void)
+{
+	unsigned char enetaddr[6];
+
+	if (dh_mac_is_in_env("ethaddr"))
+		return 0;
+
+	if (!dh_get_mac_from_eeprom(enetaddr, "eeprom0"))
+		return eth_env_set_enetaddr("ethaddr", enetaddr);
+
+	printf("%s: Unable to set mac address!\n", __func__);
+	return -ENXIO;
+}

board/dhelectronics/common/dh_common.h

@@ -0,0 +1,28 @@
+/* SPDX-License-Identifier: GPL-2.0+
+ *
+ * Copyright 2022 DENX Software Engineering GmbH, Philip Oberfichtner <pro@denx.de>
+ */
+
+/*
+ * dh_mac_is_in_env - Check if MAC address is already set
+ *
+ * @env: name of environment variable
+ * Return: true if MAC is set, false otherwise
+ */
+bool dh_mac_is_in_env(const char *env);
+
+/*
+ * dh_get_mac_from_eeprom - Get MAC address from eeprom and write it to enetaddr
+ *
+ * @enetaddr: buffer where address is to be stored
+ * @alias: alias for EEPROM device tree node
+ * Return: 0 if OK, other value on error
+ */
+int dh_get_mac_from_eeprom(unsigned char *enetaddr, const char *alias);
+
+/*
+ * dh_setup_mac_address - Try to get MAC address from various locations and write it to env
+ *
+ * Return: 0 if OK, other value on error
+ */
+int dh_setup_mac_address(void);

board/dhelectronics/common/dh_imx.c

@@ -0,0 +1,24 @@
+// SPDX-License-Identifier: GPL-2.0+
+/*
+ * Copyright 2022 Marek Vasut <marex@denx.de>
+ * Copyright 2022 DENX Software Engineering GmbH, Philip Oberfichtner <pro@denx.de>
+ */
+
+#include <asm/arch/imx-regs.h>
+#include <asm/arch/sys_proto.h>
+#include <common.h>
+#include <net.h>
+#include "dh_imx.h"
+
+int dh_imx_get_mac_from_fuse(unsigned char *enetaddr)
+{
+	/*
+	 * If IIM fuses contain valid MAC address, use it.
+	 * The IIM MAC address fuses are NOT programmed by default.
+	 */
+	imx_get_mac_from_fuse(0, enetaddr);
+	if (!is_valid_ethaddr(enetaddr))
+		return -EINVAL;
+
+	return 0;
+}

board/dhelectronics/common/dh_imx.h

@@ -0,0 +1,12 @@
+/* SPDX-License-Identifier: GPL-2.0+
+ *
+ * Copyright 2022 DENX Software Engineering GmbH, Philip Oberfichtner <pro@denx.de>
+ */
+
+/*
+ * dh_imx_get_mac_from_fuse - Get MAC address from fuse and write it to env
+ *
+ * @enetaddr: buffer where address is to be stored
+ * Return: 0 if OK, other value on error
+ */
+int dh_imx_get_mac_from_fuse(unsigned char *enetaddr);