[PATCH] ARM: dts: stm32: Configure Buck3 voltage per PMIC NVM on Avenger96

[Marek Vasut]

The Avenger96 board comes in multiple regulator configurations.
 - rev.100 or rev.200 have Buck3 preconfigured to 3V3 operation on
   boot and contains extra Enpirion EP53A8LQI DCDC converter which
   supplies the IO. Reduce Buck3 voltage to 2V9 to not waste power.
 - rev.200L have Buck3 preconfigured to 1V8 operation and have no
   Enpirion EP53A8LQI DCDC anymore, the IO is supplied from Buck3.

Configure the Buck3 voltage on this board per PMIC NVM settings and
update buck3 voltage limits in DT passed to OS before booting OS to
prevent potential hardware damage.

Signed-off-by: Marek Vasut <marex at denx.de>
Cc: Patrice Chotard <patrice.chotard at foss.st.com>
Cc: Patrick Delaunay <patrick.delaunay at foss.st.com>
---
 arch/arm/dts/stm32mp15xx-dhcor-io1v8.dtsi |   2 +-
 board/dhelectronics/dh_stm32mp1/board.c   | 109 +++++++++++++++++++++-
 2 files changed, 107 insertions(+), 4 deletions(-)

diff --git a/arch/arm/dts/stm32mp15xx-dhcor-io1v8.dtsi b/arch/arm/dts/stm32mp15xx-dhcor-io1v8.dtsi
index 9937b28548c..e20917824bf 100644
--- a/arch/arm/dts/stm32mp15xx-dhcor-io1v8.dtsi
+++ b/arch/arm/dts/stm32mp15xx-dhcor-io1v8.dtsi
@@ -19,7 +19,7 @@
 };
 
 &vdd {
-	regulator-min-microvolt = <2900000>;
+	regulator-min-microvolt = <1800000>;
 	regulator-max-microvolt = <2900000>;
 };
 
diff --git a/board/dhelectronics/dh_stm32mp1/board.c b/board/dhelectronics/dh_stm32mp1/board.c
index 67273f90992..d407f0bf592 100644
--- a/board/dhelectronics/dh_stm32mp1/board.c
+++ b/board/dhelectronics/dh_stm32mp1/board.c
@@ -594,14 +594,98 @@ static void board_init_fmc2(void)
 	setbits_le32(STM32_FMC2_BASE + STM32_FMC2_BCR1, STM32_FMC2_BCRx_FMCEN);
 }
 
+#ifdef CONFIG_DM_REGULATOR
+#define STPMIC_NVM_BUCKS_VOUT_SHR			0xfc
+#define STPMIC_NVM_BUCKS_VOUT_SHR_BUCK_1V2		0
+#define STPMIC_NVM_BUCKS_VOUT_SHR_BUCK_1V8		1
+#define STPMIC_NVM_BUCKS_VOUT_SHR_BUCK_3V0		2
+#define STPMIC_NVM_BUCKS_VOUT_SHR_BUCK_3V3		3
+#define STPMIC_NVM_BUCKS_VOUT_SHR_BUCK_MASK		GENMASK(1, 0)
+#define STPMIC_NVM_BUCKS_VOUT_SHR_BUCK_OFFSET(n)	((((n) - 1) & 3) * 2)
+static int board_get_regulator_buck3_nvm_uv_av96(int *uv)
+{
+	const void *fdt = gd->fdt_blob;
+	struct udevice *dev;
+	u8 bucks_vout = 0;
+	const char *prop;
+	int len, ret;
+
+	/* Check whether this is Avenger96 board. */
+	prop = fdt_getprop(fdt, 0, "compatible", &len);
+	if (!prop || !len)
+		return -ENODEV;
+
+	if (!strstr(prop, "avenger96"))
+		return -EINVAL;
+
+	/* Read out STPMIC1 NVM and determine default Buck3 voltage. */
+	ret = uclass_get_device_by_driver(UCLASS_MISC,
+					  DM_DRIVER_GET(stpmic1_nvm),
+					  &dev);
+	if (ret)
+		return ret;
+
+	ret = misc_read(dev, STPMIC_NVM_BUCKS_VOUT_SHR, &bucks_vout, 1);
+	if (ret != 1)
+		return -EINVAL;
+
+	bucks_vout >>= STPMIC_NVM_BUCKS_VOUT_SHR_BUCK_OFFSET(3);
+	bucks_vout &= STPMIC_NVM_BUCKS_VOUT_SHR_BUCK_MASK;
+
+	/*
+	 * Avenger96 board comes in multiple regulator configurations:
+	 * - rev.100 or rev.200 have Buck3 preconfigured to 3V3 operation on
+	 *   boot and contains extra Enpirion EP53A8LQI DCDC converter which
+	 *   supplies the IO. Reduce Buck3 voltage to 2V9 to not waste power.
+	 * - rev.200L have Buck3 preconfigured to 1V8 operation and have no
+	 *   Enpirion EP53A8LQI DCDC anymore, the IO is supplied from Buck3.
+	 */
+	if (bucks_vout == STPMIC_NVM_BUCKS_VOUT_SHR_BUCK_3V3)
+		*uv = 2900000;
+	else
+		*uv = 1800000;
+
+	return 0;
+}
+
+static void board_init_regulator_av96(void)
+{
+	struct udevice *rdev;
+	int ret, uv;
+
+	ret = board_get_regulator_buck3_nvm_uv_av96(&uv);
+	if (ret)	/* Not Avenger96 board. */
+		return;
+
+	ret = regulator_get_by_devname("buck3", &rdev);
+	if (ret)
+		return;
+
+	/* Adjust Buck3 per preconfigured PMIC voltage from NVM. */
+	regulator_set_value(rdev, uv);
+}
+
+static void board_init_regulator(void)
+{
+	board_init_regulator_av96();
+
+	regulators_enable_boot_on(_DEBUG);
+}
+#else
+static inline int board_get_regulator_buck3_nvm_uv_av96(int *uv)
+{
+	return -EINVAL;
+}
+
+static inline void board_init_regulator(void) {}
+#endif
+
 /* board dependent setup after realloc */
 int board_init(void)
 {
 	board_key_check();
 
-#ifdef CONFIG_DM_REGULATOR
-	regulators_enable_boot_on(_DEBUG);
-#endif
+	board_init_regulator();
 
 	sysconf_init();
 
@@ -721,6 +805,25 @@ int board_interface_eth_init(struct udevice *dev,
 #if defined(CONFIG_OF_BOARD_SETUP)
 int ft_board_setup(void *blob, struct bd_info *bd)
 {
+	const char *buck3path = "/soc/i2c at 5c002000/stpmic at 33/regulators/buck3";
+	int buck3off, ret, uv;
+
+	ret = board_get_regulator_buck3_nvm_uv_av96(&uv);
+	if (ret)	/* Not Avenger96 board, do not patch Buck3 in DT. */
+		return 0;
+
+	buck3off = fdt_path_offset(blob, buck3path);
+	if (buck3off < 0)	/* No Buck3 regulator found. */
+		return 0;
+
+	ret = fdt_setprop_u32(blob, buck3off, "regulator-min-microvolt", uv);
+	if (ret < 0)
+		return ret;
+
+	ret = fdt_setprop_u32(blob, buck3off, "regulator-max-microvolt", uv);
+	if (ret < 0)
+		return ret;
+
 	return 0;
 }
 #endif
-- 
2.35.1