linux-kernel - Re: [PATCH v6 06/11] iio: adc: ad7768-1: Add GPIO controller support

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Message-ID: <CAHp75VdbD4HTonEZT8O-3bsqQ70_XRnZd7vS7gdyrG2gKYBHPA@mail.gmail.com>
Date: Mon, 28 Apr 2025 09:50:43 +0300
From: Andy Shevchenko <andy.shevchenko@...il.com>
To: Jonathan Santos <Jonathan.Santos@...log.com>
Cc: linux-iio@...r.kernel.org, devicetree@...r.kernel.org, 
	linux-kernel@...r.kernel.org, linux-gpio@...r.kernel.org, 
	Sergiu Cuciurean <sergiu.cuciurean@...log.com>, andy@...nel.org, nuno.sa@...log.com, 
	Michael.Hennerich@...log.com, marcelo.schmitt@...log.com, jic23@...nel.org, 
	robh@...nel.org, krzk+dt@...nel.org, conor+dt@...nel.org, 
	marcelo.schmitt1@...il.com, linus.walleij@...aro.org, brgl@...ev.pl, 
	lgirdwood@...il.com, broonie@...nel.org, jonath4nns@...il.com, 
	dlechner@...libre.com, Bartosz Golaszewski <bartosz.golaszewski@...aro.org>
Subject: Re: [PATCH v6 06/11] iio: adc: ad7768-1: Add GPIO controller support

On Mon, Apr 28, 2025 at 3:13 AM Jonathan Santos
<Jonathan.Santos@...log.com> wrote:
>
> The AD7768-1 has the ability to control other local hardware (such as gain
> stages),to power down other blocks in the signal chain, or read local
> status signals over the SPI interface.
>
> Add direct mode conditional locks in the gpio callbacks to prevent register
> access when the device is in buffered mode.
>
> This change exports the AD7768-1's four gpios and makes them accessible
> at an upper layer.

...

> +#include <linux/gpio.h>

No way. This header must not be in any of the code. (Yes, there are
leftovers in the kernel, but work is ongoing to clean that up)

> +#include <linux/gpio/driver.h>
>  #include <linux/gpio/consumer.h>

>  #include <linux/kernel.h>

And since you are doing the big series for the driver, please drop
this header and replace it (if required) with what is used. No driver
code should use kernel.h.

>  #include <linux/module.h>

...

> struct ad7768_state {

>         struct regulator_dev *vcm_rdev;
>         unsigned int vcm_output_sel;
>         struct clk *mclk;
> +       struct gpio_chip gpiochip;
>         unsigned int mclk_freq;
>         unsigned int samp_freq;
>         struct completion completion;

Btw, have you run `pahole`? Is this the best place for a new field in
accordance with its output?

...

> +static int ad7768_gpio_set(struct gpio_chip *chip, unsigned int offset, int value)
> +{
> +       struct iio_dev *indio_dev = gpiochip_get_data(chip);
> +       struct ad7768_state *st = iio_priv(indio_dev);
> +       unsigned int val;
> +       int ret;
> +
> +       if (!iio_device_claim_direct(indio_dev))
> +               return -EBUSY;
> +
> +       ret = regmap_read(st->regmap, AD7768_REG_GPIO_CONTROL, &val);
> +       if (ret)
> +               goto err_release;
> +
> +       if (val & BIT(offset))
> +               ret = regmap_update_bits(st->regmap, AD7768_REG_GPIO_WRITE,
> +                                        BIT(offset), value << offset);

And if value happens to be > 1?
Also consider the use of regmap_assign_bits().

> +err_release:
> +       iio_device_release_direct(indio_dev);
> +
> +       return ret;
> +}

...

> +static int ad7768_gpio_init(struct iio_dev *indio_dev)
> +{
> +       struct ad7768_state *st = iio_priv(indio_dev);
> +       int ret;
> +
> +       ret = regmap_write(st->regmap, AD7768_REG_GPIO_CONTROL,
> +                          AD7768_GPIO_UNIVERSAL_EN);
> +       if (ret)
> +               return ret;
> +
> +       st->gpiochip = (struct gpio_chip) {

> +               .label = "ad7768_1_gpios",

What is '_1' for?
Also, what will happen if the device has two or more such ADCs
installed? Will they all provide _the same_ label?!

> +               .base = -1,
> +               .ngpio = 4,
> +               .parent = &st->spi->dev,
> +               .can_sleep = true,
> +               .direction_input = ad7768_gpio_direction_input,
> +               .direction_output = ad7768_gpio_direction_output,
> +               .get = ad7768_gpio_get,
> +               .set_rv = ad7768_gpio_set,
> +               .owner = THIS_MODULE,
> +       };
> +
> +       return devm_gpiochip_add_data(&st->spi->dev, &st->gpiochip, indio_dev);
> +}

...

> +       /* Only create a Chip GPIO if flagged for it */
> +       if (device_property_read_bool(&st->spi->dev, "gpio-controller")) {
> +               ret = ad7768_gpio_init(indio_dev);
> +               if (ret < 0)

Why ' < 0'?

> +                       return ret;
> +       }

-- 
With Best Regards,
Andy Shevchenko