Re: [PATCH v2 12/16] iio: adc: ad7768-1: Add GPIO controller support

[David Lechner <dlechner@baylibre.com>]

On 1/27/25 9:13 AM, Jonathan Santos wrote:
> From: Sergiu Cuciurean <sergiu.cuciurean@analog.com>
> 
> 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.
> 
> This change exports the AD7768-1's four gpios and makes them accessible
> at an upper layer.
> 
> Co-developed-by: Jonathan Santos <Jonathan.Santos@analog.com>
> Signed-off-by: Jonathan Santos <Jonathan.Santos@analog.com>
> Signed-off-by: Sergiu Cuciurean <sergiu.cuciurean@analog.com>
> ---
> v2 Changes:
> * Replaced mutex for iio_device_claim_direct_mode().
> * Use gpio-controller property to conditionally enable the
>   GPIO support.
> * OBS: when the GPIO is configured as output, we should read 
>   the current state value from AD7768_REG_GPIO_WRITE.
> ---
>  drivers/iio/adc/ad7768-1.c | 148 ++++++++++++++++++++++++++++++++++++-
>  1 file changed, 146 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/iio/adc/ad7768-1.c b/drivers/iio/adc/ad7768-1.c
> index c540583808c2..e3ea078e6ec4 100644
> --- a/drivers/iio/adc/ad7768-1.c
> +++ b/drivers/iio/adc/ad7768-1.c
> @@ -9,6 +9,8 @@
>  #include <linux/delay.h>
>  #include <linux/device.h>
>  #include <linux/err.h>
> +#include <linux/gpio.h>
> +#include <linux/gpio/driver.h>
>  #include <linux/gpio/consumer.h>
>  #include <linux/kernel.h>
>  #include <linux/module.h>
> @@ -79,6 +81,19 @@
>  #define AD7768_CONV_MODE_MSK		GENMASK(2, 0)
>  #define AD7768_CONV_MODE(x)		FIELD_PREP(AD7768_CONV_MODE_MSK, x)
>  
> +/* AD7768_REG_GPIO_CONTROL */
> +#define AD7768_GPIO_UNIVERSAL_EN	BIT(7)
> +#define AD7768_GPIO_CONTROL_MSK		GENMASK(3, 0)
> +
> +/* AD7768_REG_GPIO_WRITE */
> +#define AD7768_GPIO_WRITE_MSK		GENMASK(3, 0)
> +
> +/* AD7768_REG_GPIO_READ */
> +#define AD7768_GPIO_READ_MSK		GENMASK(3, 0)
> +
> +#define AD7768_GPIO_INPUT(x)		0x00
> +#define AD7768_GPIO_OUTPUT(x)		BIT(x)
> +
>  #define AD7768_RD_FLAG_MSK(x)		(BIT(6) | ((x) & 0x3F))
>  #define AD7768_WR_FLAG_MSK(x)		((x) & 0x3F)
>  
> @@ -160,6 +175,8 @@ struct ad7768_state {
>  	struct regulator *vref;
>  	struct mutex lock;
>  	struct clk *mclk;
> +	struct gpio_chip gpiochip;
> +	unsigned int gpio_avail_map;
>  	unsigned int mclk_freq;
>  	unsigned int samp_freq;
>  	struct completion completion;
> @@ -309,6 +326,125 @@ static int ad7768_set_dig_fil(struct ad7768_state *st,
>  	return 0;
>  }
>  
> +static int ad7768_gpio_direction_input(struct gpio_chip *chip, unsigned int offset)
> +{
> +	struct iio_dev *indio_dev = gpiochip_get_data(chip);
> +	struct ad7768_state *st = iio_priv(indio_dev);
> +	int ret;
> +
> +	ret = iio_device_claim_direct_mode(indio_dev);
> +	if (ret)
> +		return ret;

Missing iio_device_release_direct_mode() here and in other functions.

(And we are in the process of removing iio_device_claim_direct_scoped(), so
don't use that.)

> +
> +	return regmap_update_bits(st->regmap,
> +				  AD7768_REG_GPIO_CONTROL,
> +				  BIT(offset),
> +				  AD7768_GPIO_INPUT(offset));

Can be simplified to regmap_clear_bits(), then we can get rid of the odd
AD7768_GPIO_INPUT macro that ignores the argument.

> +}
> +
> +static int ad7768_gpio_direction_output(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);
> +	int ret;
> +
> +	ret = iio_device_claim_direct_mode(indio_dev);
> +	if (ret)
> +		return ret;
> +
> +	return regmap_update_bits(st->regmap,
> +				  AD7768_REG_GPIO_CONTROL,
> +				  BIT(offset),
> +				  AD7768_GPIO_OUTPUT(offset));

And regmap_set_bits() here.

> +}
> +
> +static int ad7768_gpio_get(struct gpio_chip *chip, unsigned int offset)
> +{
> +	struct iio_dev *indio_dev = gpiochip_get_data(chip);
> +	struct ad7768_state *st = iio_priv(indio_dev);
> +	unsigned int val;
> +	int ret;
> +
> +	ret = iio_device_claim_direct_mode(indio_dev);
> +	if (ret)
> +		return ret;
> +
> +	ret = regmap_read(st->regmap, AD7768_REG_GPIO_CONTROL, &val);
> +	if (ret < 0)
> +		return ret;
> +
> +	if (val & BIT(offset))
> +		ret = regmap_read(st->regmap, AD7768_REG_GPIO_WRITE, &val);
> +	else
> +		ret = regmap_read(st->regmap, AD7768_REG_GPIO_READ, &val);

Can we get a comment explaining why GPIO_READ doesn't work in output mode?

Or if it does work, we can simplify this function.


> +	if (ret < 0)
> +		return ret;
> +
> +	return !!(val & BIT(offset));
> +}
> +
> +static void 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;
> +
> +	ret = iio_device_claim_direct_mode(indio_dev);
> +	if (ret)
> +		return;
> +
> +	ret = regmap_read(st->regmap, AD7768_REG_GPIO_CONTROL, &val);
> +	if (ret < 0)
> +		return;
> +
> +	if (val & BIT(offset))
> +		regmap_update_bits(st->regmap,
> +				   AD7768_REG_GPIO_WRITE,
> +				   BIT(offset),
> +				   (value << offset));

Can remove extra ().

> +}
> +
> +static int ad7768_gpio_request(struct gpio_chip *chip, unsigned int offset)
> +{
> +	struct iio_dev *indio_dev = gpiochip_get_data(chip);
> +	struct ad7768_state *st = iio_priv(indio_dev);
> +
> +	if (!(st->gpio_avail_map & BIT(offset)))
> +		return -ENODEV;
> +
> +	st->gpio_avail_map &= ~BIT(offset);

Is this really needed? It seems like GPIO core would be keeping track already.

Also would need a .free callback to undo this action.

It seems like most ADC's with GPIO controllers don't implement .request though.

> +
> +	return 0;
> +}
> +