Re: [PATCH 0/4] rtc: stm32: add pinctrl interface to handle RTC outs

Hello,

On 11/07/2024 16:08:39+0200, Valentin Caron wrote:

This series adds a pinctrl/pinmux interface to control STM32 RTC outputs.

Theses two signals output are possible:
 - LSCO (Low Speed Clock Output) that allow to output LSE clock on a pin.
   On STM32MPU Discovery boards, this feature is used to generate a clock
   to Wifi/Bluetooth module.
 - Alarm out that allow to send a pulse on a pin when alarm A of the RTC
   expires.

First attempt [1] was based on 'st,' vendor properties, this one is based
on pinctrl and pinmux framework.

As device-trees will be upstreamed separately, here is an example:

stm32-pinctrl {
    rtc_rsvd_pins_a: rtc-rsvd-0 {
        pins {
            pinmux = <STM32_PINMUX('B', 2, AF1)>, /* OUT2 */
                     <STM32_PINMUX('I', 8, ANALOG)>; /* OUT2_RMP */
        };
    };
};

stm32-rtc {
    pinctrl-0 = <&rtc_rsvd_pins_a &rtc_alarma_pins_a>;

    /* Enable by foo-device */
    rtc_lsco_pins_a: rtc-lsco-0 {
        pins = "out2_rmp";
        function = "lsco";
    };

    /* Enable by stm32-rtc hog */
    rtc_alarma_pins_a: rtc-alarma-0 {
        pins = "out2";
        function = "alarm-a";
    };
};

foo-device {
    pinctrl-0 = <&rtc_lsco_pins_a>;
};

This all seems good to me, I let you fix the various issues that have
been reported. I was just wondering whether the LSCO clock was registered
early enough to be used but I guess you tested that.

-- 
Alexandre Belloni, co-owner and COO, Bootlin
Embedded Linux and Kernel engineering
https://bootlin.com