gpio-sim as a GPIO Interrupt for PMIC driver

elFunko — Fri, 11 Oct 2024 14:26:26 GMT

Hi everyone,

I'm currently working on getting a custom i.MX93 board up and running, and I'm facing an issue with the PMIC (the NXP PCA9451A). The problem is that the PMIC requires a GPIO interrupt to load its driver, but our board does not have any free GPIOs available.

To solve this, we came up with the idea of using a "fake" GPIO through gpio-sim or gpio-mockup, so that we can get the PMIC up and running for now. In a future revision of the board, we plan to replace this mockup GPIO with a real one. However, I'm struggling to get the PMIC driver to load, regardless of how I configure the gpio-sim node.

I've seen a linux patch from 2022 "[PATCH v2 0/3] allow gpio simulator be used as interrupt controller ", which seems to be attempting the same thing I'm trying to do. We're currently using Linux version 6.6.28-lf-6.6.y-lf-6.6.y-g81ea508ca4b7-dirty.

I've also made sure to add the necessary kernel configuration options, including:

CONFIG_GPIO_SIM=y
CONFIG_GPIOLIB=y
CONFIG_IRQ_SIM=y

Despite this, the PMIC driver does not load. Below is how I'd like the PMIC node to look in the device tree, using gpio-sim as the interrupt parent:

&lpi2c1 { #address-cells = <1>; #size-cells = <0>; clock-frequency = <400000>; pinctrl-names = "default", "sleep"; pinctrl-0 = <&pinctrl_lpi2c1>; pinctrl-1 = <&pinctrl_lpi2c1>; status = "okay"; pmic@25 { compatible = "nxp,pca9451a"; reg = <0x25>; interrupt-parent = <&gpio_sim>; interrupts = <0 IRQ_TYPE_EDGE_FALLING>;

Has anyone successfully used gpio-sim in a similar scenario, or can anyone suggest how the gpio-sim node should be configured to make this work?

Any help would be greatly appreciated!

Best regards,
Elia

Re: gpio-sim as a GPIO Interrupt for PMIC driver

elFunko — Wed, 13 Nov 2024 08:52:46 GMT

To anyone having the same question I got it to work:

/ { gpio_sim { compatible = "gpio-simulator"; bank0: bank0 { gpio-controller; #gpio-cells = <1>; ngpios = <1>; interrupt-controller; #interrupt-cells = <1>; }; }; };

i.MX Processorsのトピックgpio-sim as a GPIO Interrupt for PMIC driver

gpio-sim as a GPIO Interrupt for PMIC driver

Re: gpio-sim as a GPIO Interrupt for PMIC driver