linux-kernel - Re: [PATCH v3 12/13] iio: adc: Add support for AD7091R-8

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Message-ID: <20231210123343.2695a9dc@jic23-huawei>
Date:   Sun, 10 Dec 2023 12:33:43 +0000
From:   Jonathan Cameron <jic23@...nel.org>
To:     Marcelo Schmitt <marcelo.schmitt@...log.com>
Cc:     <apw@...onical.com>, <joe@...ches.com>, <dwaipayanray1@...il.com>,
        <lukas.bulwahn@...il.com>, <paul.cercueil@...log.com>,
        <Michael.Hennerich@...log.com>, <lars@...afoo.de>,
        <robh+dt@...nel.org>, <krzysztof.kozlowski+dt@...aro.org>,
        <conor+dt@...nel.org>, <dan.carpenter@...aro.org>,
        <marcelo.schmitt1@...il.com>, <linux-iio@...r.kernel.org>,
        <devicetree@...r.kernel.org>, <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v3 12/13] iio: adc: Add support for AD7091R-8

On Thu, 7 Dec 2023 15:42:56 -0300
Marcelo Schmitt <marcelo.schmitt@...log.com> wrote:

> Add support for Analog Devices AD7091R-2, AD7091R-4, and AD7091R-8
> low power 12-Bit SAR ADCs with SPI interface.
> Extend ad7091r-base driver so it can be used by the AD7091R-8 driver.
> 
> Signed-off-by: Marcelo Schmitt <marcelo.schmitt@...log.com>

A few trivial things inline.
Otherwise looks pretty good to me.

Jonathan
> diff --git a/drivers/iio/adc/ad7091r8.c b/drivers/iio/adc/ad7091r8.c
> new file mode 100644
> index 000000000000..8dc0f784913b
> --- /dev/null
> +++ b/drivers/iio/adc/ad7091r8.c
> @@ -0,0 +1,261 @@
> +// SPDX-License-Identifier: GPL-2.0
> +/*
> + * Analog Devices AD7091R8 12-bit SAR ADC driver
> + *
> + * Copyright 2023 Analog Devices Inc.
> + */
> +
> +#include <linux/bitfield.h>
> +#include <linux/iio/iio.h>
> +#include <linux/module.h>
> +#include <linux/regmap.h>
> +#include <linux/gpio/consumer.h>
> +#include <linux/spi/spi.h>
> +
> +#include "ad7091r-base.h"
> +
> +#define AD7091R8_REG_ADDR_MSK				GENMASK(15, 11)
> +#define AD7091R8_RD_WR_FLAG_MSK				BIT(10)
> +#define AD7091R8_REG_DATA_MSK				GENMASK(9, 0)
> +
> +#define AD7091R2_DEV_NAME				"ad7091r-2"
> +#define AD7091R4_DEV_NAME				"ad7091r-4"
> +#define AD7091R8_DEV_NAME				"ad7091r-8"
Not seeing any advantage in these macros.  It will be more readable to just
have the strings inline where the macros are currently used.

> +static int ad7091r8_gpio_setup(struct ad7091r_state *st)
> +{
> +	st->convst_gpio = devm_gpiod_get(st->dev, "adi,conversion-start",
> +					 GPIOD_OUT_LOW);
> +	if (IS_ERR(st->convst_gpio))
> +		return dev_err_probe(st->dev, PTR_ERR(st->convst_gpio),
> +				     "Error getting convst GPIO\n");
> +
> +	st->reset_gpio =  devm_gpiod_get_optional(st->dev, "reset",
> +						  GPIOD_OUT_HIGH);
> +	if (IS_ERR(st->reset_gpio))
> +		return PTR_ERR(st->reset_gpio);
Maybe a dev_err_probe() here as well both for consistency and for the
debug info that gets stashed if it's EPROBE_DEFER
> +
> +	if (st->reset_gpio) {
> +		fsleep(20);
> +		gpiod_set_value_cansleep(st->reset_gpio, 0);
> +	}
> +
> +	return 0;
> +}

> +
> +static struct ad7091r_init_info ad7091r2_init_info = {
> +	.info_no_irq = AD7091R_SPI_CHIP_INFO(2),
> +	.regmap_config = &ad7091r2_reg_conf,
> +	.ad7091r_regmap_init = &ad7091r8_regmap_init,
> +	.ad7091r_setup = &ad7091r8_gpio_setup
> +};
> +
> +static struct ad7091r_init_info ad7091r4_init_info = {
> +	.irq_info = AD7091R_SPI_CHIP_INFO_IRQ(4),
> +	.info_no_irq = AD7091R_SPI_CHIP_INFO(4),
> +	.regmap_config = &ad7091r4_reg_conf,
> +	.ad7091r_regmap_init = &ad7091r8_regmap_init,
> +	.ad7091r_setup = &ad7091r8_gpio_setup
> +};
> +
> +static struct ad7091r_init_info ad7091r8_init_info = {
> +	.irq_info = AD7091R_SPI_CHIP_INFO_IRQ(8),
> +	.info_no_irq = AD7091R_SPI_CHIP_INFO(8),
> +	.regmap_config = &ad7091r8_reg_conf,
> +	.ad7091r_regmap_init = &ad7091r8_regmap_init,
> +	.ad7091r_setup = &ad7091r8_gpio_setup
> +};
> +
> +static int ad7091r8_spi_probe(struct spi_device *spi)
> +{
> +	const struct spi_device_id *id = spi_get_device_id(spi);
> +	const struct ad7091r_init_info *init_info;
> +
> +	init_info = spi_get_device_match_data(spi);
> +	if (!init_info)
> +		return -EINVAL;
> +
> +	return ad7091r_probe(&spi->dev, id->name, init_info, NULL, spi->irq);
id->name isn't generally a good idea because we end up with lots of odd corner
cases if the of_device_id and spi_device_id tables get out of sync - which
can happen if fallback compatibles get used.

Normal way round this is just put the naming of the device in the
info structure.  Costs a little storage, but makes the code simpler
and less probe to odd corner cases.  Also, I think you already have it
in there!

> +}
> +
> +static const struct of_device_id ad7091r8_of_match[] = {
> +	{ .compatible = "adi,ad7091r2", .data = &ad7091r2_init_info },
> +	{ .compatible = "adi,ad7091r4", .data = &ad7091r4_init_info },
> +	{ .compatible = "adi,ad7091r8", .data = &ad7091r8_init_info },
> +	{ }
> +};
> +MODULE_DEVICE_TABLE(of, ad7091r8_of_match);
> +
> +static const struct spi_device_id ad7091r8_spi_id[] = {
> +	{ "ad7091r2", (kernel_ulong_t)&ad7091r2_init_info },
> +	{ "ad7091r4", (kernel_ulong_t)&ad7091r4_init_info },
> +	{ "ad7091r8", (kernel_ulong_t)&ad7091r8_init_info },
> +	{}
Trivial but be consistent on spacing for these terminators.  I like a space, so
{ } but I don't mind if an author prefers {} as long as they are consistent!

> +};
> +MODULE_DEVICE_TABLE(spi, ad7091r8_spi_id);