Wakeup on GPIO in Linux on STM32MP1

[RPiet.1]

Hello. I am working on standby/wakeup using gpio pin in stm32mp1 custom board. Going to sleep works well using gpio-keys but I can't wakeup. What bothers me most is that interrupt responsible for waking up does not set "waleup" attribute although it is defined in DTS as wakeup-source. I am not sure whether I correctly understand the concept behind exti_pwr and pwr_irq nodes so if there is anyone who can help me with a proper setup I would appreciate your help. Please find enclosed DTS.

 gpio_keys {

  compatible = "gpio-keys";

  #address-cells = <1>;

  #size-cells = <0>;

  autorepeat;

  input-name = "gpio-keys";

   button@1 {

    label = "Suspend";

    linux,code = <205>;

    gpios = <&gpioi 6 GPIO_ACTIVE_LOW>;

   };

   button@2 {

    label = "Wakeup";

    linux,code = <143>;

    interrupts-extended = <&exti_pwr 55 IRQ_TYPE_EDGE_RISING>;

    wakeup-source;

   };

 };

};

&pwr_irq {

 wakeup-gpios = <&gpioi 6 GPIO_ACTIVE_HIGH>;

};

[PatrickF]

Hi,

PI6 has no WKUP capabilities.

If you really go in SoC Standby (i.e. VDDCORE shutdown), you must use to wakeup one of the 6 available WKUP pins (e.g. PA0/WKUP1 is used on our DK2/EV1 board).

See Reference Manual

See also:

https://wiki.st.com/stm32mpu/wiki/Interrupt_overview

https://wiki.st.com/stm32mpu/wiki/PWR_internal_peripheral

Regards.

[RPiet.1]

I've seen these settings in these dts-es but I thought those i/o pins are arbitrary and any pin can be mapped there. Where those certain pins are mentioned in specification because I haven't seen it ? pon., 8 mar 2021, 17:48 użytkownik ST Community napisał:

[RPiet.1]

So what you're saying is that only PA0, PA2, PC13, PI8, PI11 and PC1 have wakeup capabilities because that's what I see in DTS ?

[PatrickF]

Wakeup capabilities are shown in Reference Manual (PWR section, e.g. in RM0436 Rev.5, Table 33. "System Low-power mode summary", or "PWR exiting from Standby mode" sub-section).

WKUP pins locations are shown on Datasheet, 6x are present on 18x18 and 12x12 packages, 4x in 16x16 and 10x10 packages.

I confirm, it is PI8 and PI11 (on some packages), plus PC13, PA0, PA2, PC1.

They are present in STM32CubeMX, PWR category.

[RPiet.1]

Thank for you support. I have one more question regarding standby. We would like to set certain IO pins with pull-ups or pull-downs during standby but it looks like vddcore is switched off during standby. It looks like in deep standby this is normal but I am wondering how could I go into other LP mode like Sleep so that vddcore is on and gpio pin values will be retained.

[PatrickF]

Yes, whenever VDDCORE if OFF (STANDBY), all IOs are hi-z (except some IOs related to VSW domain like those for RTC, TAMP).

For your case, if you want to avoid external resistors, you could use LPLV-Stop (VDDCORE only reduced, larger power than STANDBY, but GPIO settings and interrupt capabilities are kept).

Se https://wiki.st.com/stm32mpu/wiki/How_to_define_your_low-power_strategy

Regards.

[RPiet.1]

I'm trying to find whether this is somehow configurable within the Linux kernel but as for now I didn't find anything. Do you know this off the top of your head ?

[PatrickF]

I'm not specialist of this, maybe read https://wiki.st.com/stm32mpu/wiki/Power_overview or AN5109.pdf

[RPiet.1]

Thanks again. This Power overview pge guided me to the solution. It looks like kernel relies on settings made by TF-A and TF-a sets the deepest mode it has defined in DTS under

system_suspend_supported_modes = <

STM32_PM_CSLEEP_RUN

STM32_PM_CSTOP_ALLOW_STOP

STM32_PM_CSTOP_ALLOW_LP_STOP

STM32_PM_CSTOP_ALLOW_LPLV_STOP

STM32_PM_CSTOP_ALLOW_STANDBY_DDR_SR

>;

So what is needed is to define the deepest mode of your choice for the kernel to go.