Re: [PATCH 4/5] iio: adc: ti-ads1262: Add calibration support

[Jonathan Cameron <jic23@kernel.org>]

On Fri, 12 Jun 2026 17:46:22 -0500
Kurt Borja <kuurtb@gmail.com> wrote:

> Add channel calibration support.
> 
> Signed-off-by: Kurt Borja <kuurtb@gmail.com>
> ---
>  drivers/iio/adc/ti-ads1262.c | 70 +++++++++++++++++++++++++++++++++++++++++++-
>  1 file changed, 69 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/iio/adc/ti-ads1262.c b/drivers/iio/adc/ti-ads1262.c
> index 6d5f22836ad8..b33505e7fdc7 100644
> --- a/drivers/iio/adc/ti-ads1262.c
> +++ b/drivers/iio/adc/ti-ads1262.c
> @@ -217,6 +217,10 @@
>  #define ADS1262_RMUX_AVDD_AVSS			4
>  #define ADS1262_RMUX_COUNT			5
>  
> +/* The calibration word is signed 24 bits value */
> +#define ADS1262_CALIB_WORD_MAX		((int)(GENMASK(22, 0)))
> +#define ADS1262_CALIB_WORD_MIN		(-ADS1262_CALIB_WORD_MAX - 1)
> +
>  struct ads1262_channel {
>  	/* MODE0 */
>  	u8 conv_delay:4;
> @@ -453,6 +457,32 @@ static int ads1262_dev_start_one(struct ads1262 *st, u8 runmode)
>  	return 0;
>  }
>  
> +static int ads1262_read_calib(struct ads1262 *st, unsigned int reg, u32 *val)
> +{
> +	__le32 lval;
> +	int ret;
> +
> +	/*
> +	 * The calibration word is a signed 24 bit LSB-first value.

Single line comment.  However, it's also fairly clear from the code, so maybe
no comment at all. 

> +	 */
> +	ret = regmap_bulk_read(st->regmap, reg, &lval, 3);

Read it into a u8 [3] and use get_unaligned_le24()
That avoids us having to think too much about the bits that aren't
initialized and static analysis / compilers having to figure out
they don't matter. I general it is easier to understand.

> +	if (ret)
> +		return ret;
> +	*val = sign_extend32(le32_to_cpu(lval), 23);
> +
> +	return 0;
> +}
> +
> +static int ads1262_write_calib(struct ads1262 *st, unsigned int reg, u32 val)
> +{
> +	__le32 lval = cpu_to_le32(val);
> +
> +	/*
> +	 * The calibration word is a signed 24 bit LSB-first value.
> +	 */
> +	return regmap_bulk_write(st->regmap, reg, &lval, 3);

Similar with a u8 [3] for the '__le24' storage.

> +}
> +