imx8mp_var_dart: set PMIC SW_EN bit for DART-MX8M-PLUS v2.0

In the DART-MX8M-PLUS v2.0 module, the PMIC does not enable the SW_EN
bit by hardware. This issue prevents the PMIC from supplying the voltage
necessary to power the Ethernet PHY.

Read the value in the LOADSW_CTRL register and sets the SW_EN bit via
software, if necessary, to ensure that the PMIC correctly powers the
Ethernet PHY.

Signed-off-by: Alifer Moraes <alifer.m@variscite.com>
(cherry picked from commit ca1dfc1)

Author: alifermoraes

board/variscite/imx8mp_var_dart/imx8mp_var_dart.c

@@ -103,6 +103,58 @@ int var_detect_board_id(void)
 	return board_id;
 }
 
+#ifdef CONFIG_POWER_PCA9450
+#define PCA9450_I2C_BUS	0
+#define PCA9450_I2C_ADDR	0x25
+#define PCA9450_LSW_CTRL_ADDR	0x2A
+#define REG_DATA_SIZE		1
+
+int setup_sw_en_pmic(void)
+{
+	struct udevice *bus;
+	struct udevice *dev;
+	u8 reg_data[REG_DATA_SIZE];
+	int ret;
+
+	struct var_eeprom *ep = VAR_EEPROM_DATA;
+	int som_rev = SOMREV_MAJOR(ep->somrev);
+
+	/* On DART-MX8M-PLUS v2.0, SW_EN must be set by software to ensure
+	 * that the ethernet PHY is powered up. Set bit 0 of LOADSW_CTRL.
+	 */
+	if ((var_detect_board_id() == BOARD_ID_DART) && (som_rev >= 2)) {
+		ret = uclass_get_device_by_seq(UCLASS_I2C, PCA9450_I2C_BUS, &bus);
+		if (ret) {
+			printf("Can't find I2C bus %d\n", PCA9450_I2C_BUS);
+			return ret;
+		}
+
+		ret = dm_i2c_probe(bus, PCA9450_I2C_ADDR, 0, &dev);
+		if (ret) {
+			printf("Can't find device at address 0x%x\n", PCA9450_I2C_ADDR);
+			return ret;
+		}
+
+		ret = dm_i2c_read(dev, PCA9450_LSW_CTRL_ADDR, reg_data, REG_DATA_SIZE);
+		if (ret) {
+			printf("Failed to read address 0x%x\n", PCA9450_I2C_ADDR);
+			return ret;
+		}
+
+		/* Enable SW_EN by setting LOADSW_CTRL bit 0 */
+		reg_data[0] |= 0x01;
+
+		ret = dm_i2c_write(dev, PCA9450_LSW_CTRL_ADDR, reg_data, REG_DATA_SIZE);
+		if (ret) {
+			printf("Failed to write at address 0x%x\n", PCA9450_I2C_ADDR);
+			return ret;
+		}
+	}
+
+	return 0;
+}
+#endif
+
 #if CONFIG_IS_ENABLED(EFI_HAVE_CAPSULE_SUPPORT)
 struct efi_fw_image fw_images[] = {
 	{
@@ -359,6 +411,14 @@ int board_init(void)
 		extcon_ptn5150_setup(&usb_ptn5150);
 	}
 
+#ifdef CONFIG_POWER_PCA9450
+	int ret;
+
+	ret = setup_sw_en_pmic();
+	if (ret)
+		return ret;
+#endif
+
 	if (CONFIG_IS_ENABLED(FEC_MXC)) {
 		setup_fec();
 	}