linux-kernel - Re: [PATCH 2/3] iio: adc: Support ROHM BD79112 ADC/GPIO

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Message-ID: <CACRpkdbOhm4PawYZUxU1SMi8WGr-LxhR1jhSVPDvPh3TTp8SWQ@mail.gmail.com>
Date: Wed, 3 Sep 2025 00:34:43 +0200
From: Linus Walleij <linus.walleij@...aro.org>
To: Matti Vaittinen <mazziesaccount@...il.com>
Cc: Matti Vaittinen <matti.vaittinen@...rohmeurope.com>, Jonathan Cameron <jic23@...nel.org>, 
	David Lechner <dlechner@...libre.com>, Nuno Sá <nuno.sa@...log.com>, 
	Andy Shevchenko <andy@...nel.org>, Rob Herring <robh@...nel.org>, 
	Krzysztof Kozlowski <krzk+dt@...nel.org>, Conor Dooley <conor+dt@...nel.org>, 
	Bartosz Golaszewski <brgl@...ev.pl>, Marcelo Schmitt <marcelo.schmitt@...log.com>, 
	Javier Carrasco <javier.carrasco.cruz@...il.com>, 
	Tobias Sperling <tobias.sperling@...ting.com>, Antoniu Miclaus <antoniu.miclaus@...log.com>, 
	Trevor Gamblin <tgamblin@...libre.com>, Esteban Blanc <eblanc@...libre.com>, 
	Ramona Alexandra Nechita <ramona.nechita@...log.com>, 
	Thomas Bonnefille <thomas.bonnefille@...tlin.com>, Hans de Goede <hansg@...nel.org>, 
	linux-iio@...r.kernel.org, devicetree@...r.kernel.org, 
	linux-kernel@...r.kernel.org, linux-gpio@...r.kernel.org
Subject: Re: [PATCH 2/3] iio: adc: Support ROHM BD79112 ADC/GPIO

Hi Matti,

On Tue, Sep 2, 2025 at 2:24 PM Matti Vaittinen <mazziesaccount@...il.com> wrote:

> The ROHM BD79112 is an ADC/GPIO with 32 channels. The channel inputs can
> be used as ADC or GPIO. Using the GPIOs as IRQ sources isn't supported.
>
> The ADC is 12-bit, supporting input voltages up to 5.7V, and separate I/O
> voltage supply. Maximum SPI clock rate is 20 MHz (10 MHz with
> daisy-chain configuration) and maximum sampling rate is 1MSPS.
>
> The IC does also support CRC but it is not implemented in the driver.
>
> Signed-off-by: Matti Vaittinen <mazziesaccount@...il.com>

> +static int bd79112_gpio_dir_get(struct gpio_chip *gc, unsigned int offset)
> +static int bd79112_gpio_get(struct gpio_chip *gc, unsigned int offset)
> +static int bd79112_gpio_set(struct gpio_chip *gc, unsigned int offset,
> +                           int value)
> +static int bd79112_gpio_set_multiple(struct gpio_chip *gc, unsigned long *mask,
> +                                    unsigned long *bits)
> +static int bd79112_gpio_dir_set(struct bd79112_data *data, unsigned int offset,
> +                               int dir)
> +static int bd79112_gpio_input(struct gpio_chip *gc, unsigned int offset)
> +static int bd79112_gpio_output(struct gpio_chip *gc, unsigned int offset,
> +                              int value)

This looks like it could use

select GPIO_REGMAP

#include <linux/gpio/regmap.h>

struct gpio_regmap_config config = {};

etc. Did you check out the GPIO_REGMAP
helper library? It can work wonders to reduce code
footprint, just git grep and look a bit at what the drivers
using it does.

Yours,
Linus Walleij