stm32mp1: disable USB phy supply in sp_min

PMIC ldo4 (vdd_usb 3v3) regulator is enabled in PMIC NVM for boot from USB.
This regulator is used by the USB HS phy.
There is a requirement in AN5031 [1] regarding this regulator:
"VDD3V3_USBHS must not be present unless VDDA1V8_REG is present, otherwise
permanent STM32MP15x lines damage could occur. Must be ensured by PMIC
ranking order or with external component in case of discrete component
power supply implementation".
VDD3V3_USBHS is PMIC vdd_usb regulator, provided by LDO4.
VDDA1V8_REG is PWR reg18 regulator.
It means that vdd_usb must not be ON unless reg18 is ON.
To follow this requirement and ensure vdd_usb will not be ON while reg18
OFF, disable ldo4 regulator.

[1] https://www.st.com/resource/en/application_note/dm00389996-getting-started-with-stm32mp151-stm32mp153-and-stm32mp157-line-hardware-development-stmicroelectronics.pdf



Change-Id: I31adcba720cdee8f2737635821c2273c4835edfb
Signed-off-by: Amelie Delaunay <amelie.delaunay@foss.st.com>
Reviewed-on: https://gerrit.st.com/c/mpu/oe/st/tf-a/+/192905


Reviewed-by: CITOOLS <MDG-smet-aci-reviews@list.st.com>
Reviewed-by: CIBUILD <MDG-smet-aci-builds@list.st.com>
Reviewed-by: Lionel DEBIEVE <lionel.debieve@foss.st.com>
Reviewed-by: Yann GAUTIER <yann.gautier@foss.st.com>

fdts/stm32mp15-bl32.dtsi

@@ -21,7 +21,6 @@
 		/delete-node/ spi@58003000;
 		/delete-node/ sdmmc@58005000;
 		/delete-node/ sdmmc@58007000;
-		/delete-node/ usbphyc@5a006000;
 		/delete-node/ spi@5c001000;
 		/delete-node/ stgen@5c008000;
 		/delete-node/ i2c@5c009000;

plat/st/common/include/stm32mp_common.h

@@ -26,6 +26,7 @@ bool stm32mp_is_auth_supported(void);
 
 const char *stm32mp_get_cpu_supply_name(void);
 const char *stm32mp_get_vdd_supply_name(void);
+const char *stm32mp_get_usb_phy_supply_name(void);
 
 /* Return the base address of the DDR controller */
 uintptr_t stm32mp_ddrctrl_base(void);

plat/st/common/include/stm32mp_dt.h

@@ -46,6 +46,7 @@ int dt_get_all_opp_freqvolt(uint32_t *count, uint32_t *freq_khz_array,
 uint32_t dt_get_pwr_vdd_voltage(void);
 const char *dt_get_vdd_regulator_name(void);
 const char *dt_get_cpu_regulator_name(void);
+const char *dt_get_usb_phy_regulator_name(void);
 const char *dt_get_board_model(void);
 int fdt_get_gpio_bank_pin_count(unsigned int bank);
 

plat/st/common/stm32mp_common.c

@@ -183,6 +183,22 @@ const char *stm32mp_get_vdd_supply_name(void)
 	return supply;
 }
 
+/* Return USB phy supply name */
+const char *stm32mp_get_usb_phy_supply_name(void)
+{
+	const char *supply = NULL;
+
+	if (dt_pmic_status() > 0) {
+		const char *regulator = dt_get_usb_phy_regulator_name();
+
+		if (regulator != NULL) {
+			dt_pmic_find_supply(&supply, regulator);
+		}
+	}
+
+	return supply;
+}
+
 #if TRUSTED_BOARD_BOOT && STM32MP_USE_STM32IMAGE
 /* Save pointer to last loaded header */
 static boot_api_image_header_t *latest_stm32_header;

plat/st/common/stm32mp_dt.c

@@ -538,6 +538,30 @@ const char *dt_get_cpu_regulator_name(void)
 	return dt_get_regulator_name(node, "cpu-supply");
 }
 
+/*******************************************************************************
+ * This function retrieves USB phy regulator name from DT.
+ * Returns string taken from supply node, NULL otherwise.
+ ******************************************************************************/
+const char *dt_get_usb_phy_regulator_name(void)
+{
+	int node = fdt_node_offset_by_compatible(fdt, -1, DT_USBPHYC_COMPAT);
+	int subnode;
+	const char *reg_name = NULL;
+
+	if (node < 0) {
+		return NULL;
+	}
+
+	fdt_for_each_subnode(subnode, fdt, node) {
+		reg_name = dt_get_regulator_name(subnode, "phy-supply");
+		if (reg_name != NULL) {
+			return reg_name;
+		}
+	}
+
+	return NULL;
+}
+
 /*******************************************************************************
  * This function retrieves board model from DT
  * Returns string taken from model node, NULL otherwise

plat/st/stm32mp1/sp_min/sp_min_setup.c

@@ -161,6 +161,23 @@ static void initialize_pll1_settings(void)
 	}
 }
 
+static void disable_usb_phy_regulator(void)
+{
+	if (dt_pmic_status() > 0) {
+		const char *name = stm32mp_get_usb_phy_supply_name();
+		int ret;
+
+		if (name == NULL) {
+			return;
+		}
+
+		ret = stpmic1_regulator_disable(name);
+		if (ret < 0) {
+			WARN("USBPHYC phy-supply (%s) disable failed\n", name);
+		}
+	}
+}
+
 /*******************************************************************************
  * Interrupt handler for FIQ (secure IRQ)
  ******************************************************************************/
@@ -524,6 +541,8 @@ void sp_min_early_platform_setup2(u_register_t arg0, u_register_t arg1,
 		initialize_pmic();
 	}
 
+	disable_usb_phy_regulator();
+
 	initialize_pll1_settings();
 
 	stm32mp1_init_lp_states();

plat/st/stm32mp1/stm32mp1_def.h

@@ -653,6 +653,7 @@ static inline uint32_t tamp_bkpr(uint32_t idx)
 #define DT_PWR_COMPAT			"st,stm32mp1,pwr-reg"
 #define DT_RCC_CLK_COMPAT		"st,stm32mp1-rcc"
 #define DT_RCC_SEC_CLK_COMPAT		"st,stm32mp1-rcc-secure"
+#define DT_USBPHYC_COMPAT		"st,stm32mp1-usbphyc"
 
 #define DT_PLL1_NODE_NAME		"st,pll@0"