Linux "gpio-poweroff" won't load

[allard]

I'm trying to add the linux "gpio-poweroff" function to the distribution package. I've added the following to my device tree:

gpio-poweroff {
	compatible = "gpio-poweroff";
	gpios = <&gpioe 1 GPIO_ACTIVE_HIGH>;
	timeout-ms = <3000>;
};

The kernel/device tree compiles OK, but the poweroff function does not work. The logs give the following lines about the poweroff:

[ 1.482136] poweroff-gpio gpio-poweroff: gpio_poweroff_probe: pm_power_off function already registered
[ 1.482174] poweroff-gpio: probe of gpio-poweroff failed with error -16

So I guess openSTLinux already has some handler attached? How do I disable this?

[Christophe Guibout]

Hi @allard​ ,

gpio-poweroff is not loadable because STM32MP supports power domains.

pm_power_off is already registered in stm32_pm_domain_add function (drivers/soc/st/stm32_pm_domain.c) :

domain->genpd.power_off = stm32_pd_power_off;

This feature is under CONFIG_STM32_PM_DOMAINS switch, but I don't recommand to disable it as it's part of SoC.

BR,

Christophe

[Emma]

Hi @allard​ ,

gpio-poweroff is registered to psci_sys_poweroff in firmware/psci.c which invokes a PSCI (Power State Coordination Interface

) function which is implemented in TF-A.

I added code to set my poweroff gpio in TF-A. Not sure if this is the correct way to do it. If you do this, also note that the system_off_mode is defined to STM32_PM_CSTOP_ALLOW_STANDBY_DDR_OFF in the CubeMX-generated device tree for TF-A; I changed it to STM32_PM_SHUTDOWN.

[SMich.1]

hi, can you sow me some example of how to add gpio in tf-a to power off my board?

[Emma]

In file plat/st/stm32mp1/stm32mp1_low_power.c, function enter_shutdown(void) I put the following code after the DDR has been set in self-refresh:

/* Activate the poweroff GPIO (active low) */

uint32_t poweroff_gpio_clk = GPIOB;

uintptr_t poweroff_gpio_port = GPIOB_BASE;

uint32_t poweroff_gpio_pin = 10;

stm32mp_clk_enable(poweroff_gpio_clk);

/* Bit Reset Register (BRR): Set bit to set low output value */

mmio_setbits_32(poweroff_gpio_port + 0x28, 1 << poweroff_gpio_pin);

/* Output Type Register (OTYPER): Clear bit to configure push-pull */

mmio_clrbits_32(poweroff_gpio_port + 0x04, 1 << poweroff_gpio_pin);

/* Mode Register (MODER): 01 for GPIO output */

mmio_clrsetbits_32(poweroff_gpio_port, 1 << (poweroff_gpio_pin*2 +1),

                  1 << (poweroff_gpio_pin*2));

udelay(100);

/* If that didn't work, switch off the PMIC */

If your GPIO is active high, use BSRR (offset 0x18) instead of BRR.

Also set system_off_soc_mode to <STM32_PM_SHUTDOWN> in your device tree.

[allard]

@Emma​ @Christophe Guibout​ 

This should be enough info to get me going, thanks both.

[Rflor]

Hi everyone,

I’m facing the same issue described by SScar.2 and I would like to ask for confirmation that I’m modifying the correct place.My goal is to generate an active-HIGH GPIO signal after the system power-off sequence, to act as a PS_HOLD signal that cuts the external power supply.I tried to implement the code shared by Emma in the past, but the original function she mentioned (enter_shutdown()) no longer exists in the current TF-A sources.
So I attempted to adapt it to the current code structure.

I modified TF-A in the following way: myir-st-tfa/plat/st/stm32mp1/stm32mp1_pm.c

I added this code inside the stm32_system_off() path to force an active-HIGH GPIO (PE4):

/* --- POWER OFF GPIO (active HIGH) --- */

uint32_t poweroff_gpio_clk = GPIOE;
uintptr_t poweroff_gpio_port = GPIOE_BASE;
uint32_t poweroff_gpio_pin = 4;

/* Enable GPIO clock */
stm32mp_clk_enable(poweroff_gpio_clk);

/* Configure output push-pull */
mmio_clrbits_32(poweroff_gpio_port + 0x04, 1 << poweroff_gpio_pin);

/* Configure as output (MODER = 01) */
mmio_clrsetbits_32(poweroff_gpio_port + 0x00,
 3U << (poweroff_gpio_pin * 2),
 1U << (poweroff_gpio_pin * 2));

/* Set pin HIGH using BSRR */
mmio_write_32(poweroff_gpio_port + 0x18,
 1U << poweroff_gpio_pin);

udelay(100);

I also modified the TF-A fw-config DTS: myir-st-tfa/fdts/myb-stm32mp135x-512m-fw-config.dts

&{/} {
system_off_soc_mode = <STM32_PM_SHUTDOWN>;
};

Then I rebuilt TF-A

The firmware builds correctly, but when I shut down the system (using shutdown -h now or from my application), I do not see any change on the GPIO when measuring with an oscilloscope.

Is this code placed in the correct location for a PSCI SYSTEM_OFF sequence on STM32MP13x? 

Or is the power-off flow handled by OP-TEE, meaning the GPIO should be toggled somewhere else?

Am I missing a required pinctrl or secure configuration for GPIO usage in TF-A/OP-TEE?

Any guidance would be very appreciated.
Thanks in advance.