Re: [PATCH v4 5/5] iio: pressure: dps310: add Zilltek ZTS8032 support

[Jonathan Cameron <jic23@kernel.org>]

On Fri, 16 Oct 2026 18:35:33 +0300
Paulius Zaleckas <paulius.zaleckas@gmail.com> wrote:

> The Zilltek ZTS8032 has the DPS310 register map, scale factors and
> compensation, with these differences:
> 
> - two more pressure coefficients, c31 and c40 at 0x22-0x25, adding
>   c40 * Praw_sc^4 + c31 * Traw_sc * Praw_sc^3 to the polynomial
> - TMP_EXT is MEAS_CFG bit 3, and the temperature coefficients are for
>   the internal sensor (COEF_SRCE reads 0x06). TMP_CFG bit 7 is the top
>   bit of a 4-bit TMP_RATE, so the DPS310 TMP_EXT write would select a
>   25/16 Hz background rate instead of the external sensor.
> - product ID 0x11 instead of 0x10, the driver does not check it
> 
> Add its chip data, reading 22 coefficient bytes and leaving TMP_CFG at
> 0, a Horner step for each of c40 and c31, and the I2C and OF IDs.
> 
> Tested on a ZTS8032 over I2C: in_pressure_input is within 1 Pa of the
> datasheet formula evaluated from the raw and coefficient registers at
> every oversampling rate from 1 to 128, and TMP_CFG reads 0x00 after
> probe.
> 
> Assisted-by: LLM
> Reviewed-by: Andy Shevchenko <andriy.shevchenko@intel.com>
> Signed-off-by: Paulius Zaleckas <paulius.zaleckas@gmail.com>

Just a few small things.

Thanks,

Jonathan

> diff --git a/drivers/iio/pressure/dps310.c b/drivers/iio/pressure/dps310.c
> index d0a2f6c6ec48..a97e82843dcd 100644
> --- a/drivers/iio/pressure/dps310.c
> +++ b/drivers/iio/pressure/dps310.c

>  static const struct dps310_chip_info dps310_chip_info = {
> @@ -101,6 +107,14 @@ static const struct dps310_chip_info dps310_chip_info = {
>  	.coef_len = DPS310_COEF_LEN,
>  };
>  
> +/* TMP_CFG bit 7 is a rate bit here; the internal sensor is the default */

This is the comment that really confused me and lead to suggestion
of using a boolean for whether it was the external sensor or not.

> +static const struct dps310_chip_info zts8032_chip_info = {
> +	.name = "zts8032",
> +	.tmp_cfg = 0,
> +	.coef_len = ZTS8032_COEF_LEN,
> +	.has_c31_c40 = true,
> +};
> +
>  struct dps310_data {
>  	struct i2c_client *client;
>  	struct regmap *regmap;
> @@ -109,6 +123,7 @@ struct dps310_data {
>  
>  	s32 c0, c1;
>  	s32 c00, c10, c20, c30, c01, c11, c21;
> +	s32 c31, c40;
>  	s32 pressure_raw;
>  	s32 temp_raw;
>  	bool timeout_recovery_failed;
> @@ -211,6 +226,11 @@ static int dps310_get_coefs(struct dps310_data *data)
>  	c30 = (coef[16] << 8) | coef[17];
>  	data->c30 = sign_extend32(c30, 15);
>  
> +	if (data->info->has_c31_c40) {
> +		data->c31 = sign_extend32((coef[18] << 8) | coef[19], 15);
> +		data->c40 = sign_extend32((coef[20] << 8) | coef[21], 15);

Obviously lots of it here already but ideally use

data->c31 = sign_extend32(get_unaligned_be16(&coef[18]), 15);
etc

> +	}
> +
>  	return 0;