Re: [PATCH v9 1/3] iio: pressure: bmp280: Generalize read_*() functions

From: Adam Rizkalla
Date: Sun Jul 14 2024 - 18:17:06 EST

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On Fri, Jun 28, 2024 at 07:17:24PM +0200, Vasileios Amoiridis wrote:
> Add the coefficients for the IIO standard units and the IIO value
> inside the chip_info structure.
>
> Move the calculations for the IIO unit compatibility from inside the
> read_{temp,press,humid}() functions and move them to the general
> read_raw() function.
>
> In this way, all the data for the calculation of the value are
> located in the chip_info structure of the respective sensor.
>
> Signed-off-by: Vasileios Amoiridis <vassilisamir@xxxxxxxxx>
> ---
> drivers/iio/pressure/bmp280-core.c | 168 +++++++++++++++++------------
> drivers/iio/pressure/bmp280.h | 13 ++-
> 2 files changed, 108 insertions(+), 73 deletions(-)
>
> diff --git a/drivers/iio/pressure/bmp280-core.c b/drivers/iio/pressure/bmp280-core.c
> index 49081b729618..9ff26a8e85d3 100644
> --- a/drivers/iio/pressure/bmp280-core.c
> +++ b/drivers/iio/pressure/bmp280-core.c
> @@ -445,10 +445,8 @@ static u32 bmp280_compensate_press(struct bmp280_data *data,
> return (u32)p;
> }
>
> -static int bmp280_read_temp(struct bmp280_data *data,
> - int *val, int *val2)
> +static int bmp280_read_temp(struct bmp280_data *data, s32 *comp_temp)
> {
> - s32 comp_temp;
> u32 adc_temp;
> int ret;
>
> @@ -456,16 +454,15 @@ static int bmp280_read_temp(struct bmp280_data *data,
> if (ret)
> return ret;
>
> - comp_temp = bmp280_compensate_temp(data, adc_temp);
> + *comp_temp = bmp280_compensate_temp(data, adc_temp);
>
> - *val = comp_temp * 10;
> - return IIO_VAL_INT;
> + return 0;
> }
>
> -static int bmp280_read_press(struct bmp280_data *data,
> - int *val, int *val2)
> +static int bmp280_read_press(struct bmp280_data *data, u32 *comp_press)
> {
> - u32 comp_press, adc_press, t_fine;
> + u32 adc_press;
> + s32 t_fine;
> int ret;
>
> ret = bmp280_get_t_fine(data, &t_fine);
> @@ -476,17 +473,13 @@ static int bmp280_read_press(struct bmp280_data *data,
> if (ret)
> return ret;
>
> - comp_press = bmp280_compensate_press(data, adc_press, t_fine);
> -
> - *val = comp_press;
> - *val2 = 256000;
> + *comp_press = bmp280_compensate_press(data, adc_press, t_fine);
>
> - return IIO_VAL_FRACTIONAL;
> + return 0;
> }
>
> -static int bme280_read_humid(struct bmp280_data *data, int *val, int *val2)
> +static int bme280_read_humid(struct bmp280_data *data, u32 *comp_humidity)
> {
> - u32 comp_humidity;
> u16 adc_humidity;
> s32 t_fine;
> int ret;
> @@ -499,11 +492,9 @@ static int bme280_read_humid(struct bmp280_data *data, int *val, int *val2)
> if (ret)
> return ret;
>
> - comp_humidity = bme280_compensate_humidity(data, adc_humidity, t_fine);
> -
> - *val = comp_humidity * 1000 / 1024;
> + *comp_humidity = bme280_compensate_humidity(data, adc_humidity, t_fine);
>
> - return IIO_VAL_INT;
> + return 0;
> }
>
> static int bmp280_read_raw_impl(struct iio_dev *indio_dev,
> @@ -511,6 +502,8 @@ static int bmp280_read_raw_impl(struct iio_dev *indio_dev,
> int *val, int *val2, long mask)
> {
> struct bmp280_data *data = iio_priv(indio_dev);
> + int chan_value;
> + int ret;
>
> guard(mutex)(&data->lock);
>
> @@ -518,11 +511,29 @@ static int bmp280_read_raw_impl(struct iio_dev *indio_dev,
> case IIO_CHAN_INFO_PROCESSED:
> switch (chan->type) {
> case IIO_HUMIDITYRELATIVE:
> - return data->chip_info->read_humid(data, val, val2);
> + ret = data->chip_info->read_humid(data, &chan_value);
> + if (ret)
> + return ret;
> +
> + *val = data->chip_info->humid_coeffs[0] * chan_value;
> + *val2 = data->chip_info->humid_coeffs[1];
> + return data->chip_info->humid_coeffs_type;
> case IIO_PRESSURE:
> - return data->chip_info->read_press(data, val, val2);
> + ret = data->chip_info->read_press(data, &chan_value);
> + if (ret)
> + return ret;
> +
> + *val = data->chip_info->press_coeffs[0] * chan_value;
> + *val2 = data->chip_info->press_coeffs[1];
> + return data->chip_info->press_coeffs_type;
> case IIO_TEMP:
> - return data->chip_info->read_temp(data, val, val2);
> + ret = data->chip_info->read_temp(data, &chan_value);
> + if (ret)
> + return ret;
> +
> + *val = data->chip_info->temp_coeffs[0] * chan_value;
> + *val2 = data->chip_info->temp_coeffs[1];
> + return data->chip_info->temp_coeffs_type;
> default:
> return -EINVAL;
> }
> @@ -822,6 +833,8 @@ static int bmp280_chip_config(struct bmp280_data *data)
>
> static const int bmp280_oversampling_avail[] = { 1, 2, 4, 8, 16 };
> static const u8 bmp280_chip_ids[] = { BMP280_CHIP_ID };
> +static const int bmp280_temp_coeffs[] = { 10, 1 };
> +static const int bmp280_press_coeffs[] = { 1, 256000 };
>
> const struct bmp280_chip_info bmp280_chip_info = {
> .id_reg = BMP280_REG_ID,
> @@ -850,6 +863,11 @@ const struct bmp280_chip_info bmp280_chip_info = {
> .num_oversampling_press_avail = ARRAY_SIZE(bmp280_oversampling_avail),
> .oversampling_press_default = BMP280_OSRS_PRESS_16X - 1,
>
> + .temp_coeffs = bmp280_temp_coeffs,
> + .temp_coeffs_type = IIO_VAL_FRACTIONAL,
> + .press_coeffs = bmp280_press_coeffs,
> + .press_coeffs_type = IIO_VAL_FRACTIONAL,
> +
> .chip_config = bmp280_chip_config,
> .read_temp = bmp280_read_temp,
> .read_press = bmp280_read_press,
> @@ -877,6 +895,7 @@ static int bme280_chip_config(struct bmp280_data *data)
> }
>
> static const u8 bme280_chip_ids[] = { BME280_CHIP_ID };
> +static const int bme280_humid_coeffs[] = { 1000, 1024 };
>
> const struct bmp280_chip_info bme280_chip_info = {
> .id_reg = BMP280_REG_ID,
> @@ -899,6 +918,13 @@ const struct bmp280_chip_info bme280_chip_info = {
> .num_oversampling_humid_avail = ARRAY_SIZE(bmp280_oversampling_avail),
> .oversampling_humid_default = BME280_OSRS_HUMIDITY_16X - 1,
>
> + .temp_coeffs = bmp280_temp_coeffs,
> + .temp_coeffs_type = IIO_VAL_FRACTIONAL,
> + .press_coeffs = bmp280_press_coeffs,
> + .press_coeffs_type = IIO_VAL_FRACTIONAL,
> + .humid_coeffs = bme280_humid_coeffs,
> + .humid_coeffs_type = IIO_VAL_FRACTIONAL,
> +
> .chip_config = bme280_chip_config,
> .read_temp = bmp280_read_temp,
> .read_press = bmp280_read_press,
> @@ -1091,9 +1117,8 @@ static u32 bmp380_compensate_press(struct bmp280_data *data,
> return comp_press;
> }
>
> -static int bmp380_read_temp(struct bmp280_data *data, int *val, int *val2)
> +static int bmp380_read_temp(struct bmp280_data *data, s32 *comp_temp)
> {
> - s32 comp_temp;
> u32 adc_temp;
> int ret;
>
> @@ -1101,15 +1126,14 @@ static int bmp380_read_temp(struct bmp280_data *data, int *val, int *val2)
> if (ret)
> return ret;
>
> - comp_temp = bmp380_compensate_temp(data, adc_temp);
> + *comp_temp = bmp380_compensate_temp(data, adc_temp);
>
> - *val = comp_temp * 10;
> - return IIO_VAL_INT;
> + return 0;
> }
>
> -static int bmp380_read_press(struct bmp280_data *data, int *val, int *val2)
> +static int bmp380_read_press(struct bmp280_data *data, u32 *comp_press)
> {
> - u32 adc_press, comp_press, t_fine;
> + u32 adc_press, t_fine;
> int ret;
>
> ret = bmp380_get_t_fine(data, &t_fine);
> @@ -1120,12 +1144,9 @@ static int bmp380_read_press(struct bmp280_data *data, int *val, int *val2)
> if (ret)
> return ret;
>
> - comp_press = bmp380_compensate_press(data, adc_press, t_fine);
> -
> - *val = comp_press;
> - *val2 = 100000;
> + *comp_press = bmp380_compensate_press(data, adc_press, t_fine);
>
> - return IIO_VAL_FRACTIONAL;
> + return 0;
> }
>
> static int bmp380_read_calib(struct bmp280_data *data)
> @@ -1296,6 +1317,8 @@ static int bmp380_chip_config(struct bmp280_data *data)
> static const int bmp380_oversampling_avail[] = { 1, 2, 4, 8, 16, 32 };
> static const int bmp380_iir_filter_coeffs_avail[] = { 1, 2, 4, 8, 16, 32, 64, 128};
> static const u8 bmp380_chip_ids[] = { BMP380_CHIP_ID, BMP390_CHIP_ID };
> +static const int bmp380_temp_coeffs[] = { 10, 1 };
> +static const int bmp380_press_coeffs[] = { 1, 100000 };
>
> const struct bmp280_chip_info bmp380_chip_info = {
> .id_reg = BMP380_REG_ID,
> @@ -1323,6 +1346,11 @@ const struct bmp280_chip_info bmp380_chip_info = {
> .num_iir_filter_coeffs_avail = ARRAY_SIZE(bmp380_iir_filter_coeffs_avail),
> .iir_filter_coeff_default = 2,
>
> + .temp_coeffs = bmp380_temp_coeffs,
> + .temp_coeffs_type = IIO_VAL_FRACTIONAL,
> + .press_coeffs = bmp380_press_coeffs,
> + .press_coeffs_type = IIO_VAL_FRACTIONAL,
> +
> .chip_config = bmp380_chip_config,
> .read_temp = bmp380_read_temp,
> .read_press = bmp380_read_press,
> @@ -1443,9 +1471,9 @@ static int bmp580_nvm_operation(struct bmp280_data *data, bool is_write)
> * for what is expected on IIO ABI.
> */
>
> -static int bmp580_read_temp(struct bmp280_data *data, int *val, int *val2)
> +static int bmp580_read_temp(struct bmp280_data *data, s32 *raw_temp)
> {
> - s32 raw_temp;
> + s32 value_temp;
> int ret;
>
> ret = regmap_bulk_read(data->regmap, BMP580_REG_TEMP_XLSB, data->buf,
> @@ -1455,25 +1483,19 @@ static int bmp580_read_temp(struct bmp280_data *data, int *val, int *val2)
> return ret;
> }
>
> - raw_temp = get_unaligned_le24(data->buf);
> - if (raw_temp == BMP580_TEMP_SKIPPED) {
> + value_temp = get_unaligned_le24(data->buf);
> + if (value_temp == BMP580_TEMP_SKIPPED) {
> dev_err(data->dev, "reading temperature skipped\n");
> return -EIO;
> }
> + *raw_temp = sign_extend32(value_temp, 23);
>
> - /*
> - * Temperature is returned in Celsius degrees in fractional
> - * form down 2^16. We rescale by x1000 to return millidegrees
> - * Celsius to respect IIO ABI.
> - */
> - raw_temp = sign_extend32(raw_temp, 23);
> - *val = ((s64)raw_temp * 1000) / (1 << 16);
> - return IIO_VAL_INT;
> + return 0;
> }
>
> -static int bmp580_read_press(struct bmp280_data *data, int *val, int *val2)
> +static int bmp580_read_press(struct bmp280_data *data, u32 *raw_press)
> {
> - u32 raw_press;
> + u32 value_press;
> int ret;
>
> ret = regmap_bulk_read(data->regmap, BMP580_REG_PRESS_XLSB, data->buf,
> @@ -1483,18 +1505,14 @@ static int bmp580_read_press(struct bmp280_data *data, int *val, int *val2)
> return ret;
> }
>
> - raw_press = get_unaligned_le24(data->buf);
> - if (raw_press == BMP580_PRESS_SKIPPED) {
> + value_press = get_unaligned_le24(data->buf);
> + if (value_press == BMP580_PRESS_SKIPPED) {
> dev_err(data->dev, "reading pressure skipped\n");
> return -EIO;
> }
> - /*
> - * Pressure is returned in Pascals in fractional form down 2^16.
> - * We rescale /1000 to convert to kilopascal to respect IIO ABI.
> - */
> - *val = raw_press;
> - *val2 = 64000; /* 2^6 * 1000 */
> - return IIO_VAL_FRACTIONAL;
> + *raw_press = value_press;
> +
> + return 0;
> }
>
> static const int bmp580_odr_table[][2] = {
> @@ -1830,6 +1848,9 @@ static int bmp580_chip_config(struct bmp280_data *data)
>
> static const int bmp580_oversampling_avail[] = { 1, 2, 4, 8, 16, 32, 64, 128 };
> static const u8 bmp580_chip_ids[] = { BMP580_CHIP_ID, BMP580_CHIP_ID_ALT };
> +/* Instead of { 1000, 16 } we do this, to avoid overflow issues */
> +static const int bmp580_temp_coeffs[] = { 125, 13 };

I'm not really sure what we gain here from using 125/13 instead of
250/14...but I don't think it hurts either.

I don't have a way to test this with the latest kernel release
currently, but lgtm.

Acked-by: Adam Rizkalla <ajarizzo@xxxxxxxxx>

> +static const int bmp580_press_coeffs[] = { 1, 64000};
>
> const struct bmp280_chip_info bmp580_chip_info = {
> .id_reg = BMP580_REG_CHIP_ID,
> @@ -1856,6 +1877,11 @@ const struct bmp280_chip_info bmp580_chip_info = {
> .num_iir_filter_coeffs_avail = ARRAY_SIZE(bmp380_iir_filter_coeffs_avail),
> .iir_filter_coeff_default = 2,
>
> + .temp_coeffs = bmp580_temp_coeffs,
> + .temp_coeffs_type = IIO_VAL_FRACTIONAL_LOG2,
> + .press_coeffs = bmp580_press_coeffs,
> + .press_coeffs_type = IIO_VAL_FRACTIONAL,
> +
> .chip_config = bmp580_chip_config,
> .read_temp = bmp580_read_temp,
> .read_press = bmp580_read_press,
> @@ -2011,9 +2037,8 @@ static s32 bmp180_compensate_temp(struct bmp280_data *data, u32 adc_temp)
> return (bmp180_calc_t_fine(data, adc_temp) + 8) / 16;
> }
>
> -static int bmp180_read_temp(struct bmp280_data *data, int *val, int *val2)
> +static int bmp180_read_temp(struct bmp280_data *data, s32 *comp_temp)
> {
> - s32 comp_temp;
> u32 adc_temp;
> int ret;
>
> @@ -2021,10 +2046,9 @@ static int bmp180_read_temp(struct bmp280_data *data, int *val, int *val2)
> if (ret)
> return ret;
>
> - comp_temp = bmp180_compensate_temp(data, adc_temp);
> + *comp_temp = bmp180_compensate_temp(data, adc_temp);
>
> - *val = comp_temp * 100;
> - return IIO_VAL_INT;
> + return 0;
> }
>
> static int bmp180_read_press_adc(struct bmp280_data *data, u32 *adc_press)
> @@ -2087,9 +2111,9 @@ static u32 bmp180_compensate_press(struct bmp280_data *data, u32 adc_press,
> return p + ((x1 + x2 + 3791) >> 4);
> }
>
> -static int bmp180_read_press(struct bmp280_data *data, int *val, int *val2)
> +static int bmp180_read_press(struct bmp280_data *data, u32 *comp_press)
> {
> - u32 comp_press, adc_press;
> + u32 adc_press;
> s32 t_fine;
> int ret;
>
> @@ -2101,12 +2125,9 @@ static int bmp180_read_press(struct bmp280_data *data, int *val, int *val2)
> if (ret)
> return ret;
>
> - comp_press = bmp180_compensate_press(data, adc_press, t_fine);
> -
> - *val = comp_press;
> - *val2 = 1000;
> + *comp_press = bmp180_compensate_press(data, adc_press, t_fine);
>
> - return IIO_VAL_FRACTIONAL;
> + return 0;
> }
>
> static int bmp180_chip_config(struct bmp280_data *data)
> @@ -2117,6 +2138,8 @@ static int bmp180_chip_config(struct bmp280_data *data)
> static const int bmp180_oversampling_temp_avail[] = { 1 };
> static const int bmp180_oversampling_press_avail[] = { 1, 2, 4, 8 };
> static const u8 bmp180_chip_ids[] = { BMP180_CHIP_ID };
> +static const int bmp180_temp_coeffs[] = { 100, 1 };
> +static const int bmp180_press_coeffs[] = { 1, 1000 };
>
> const struct bmp280_chip_info bmp180_chip_info = {
> .id_reg = BMP280_REG_ID,
> @@ -2137,6 +2160,11 @@ const struct bmp280_chip_info bmp180_chip_info = {
> ARRAY_SIZE(bmp180_oversampling_press_avail),
> .oversampling_press_default = BMP180_MEAS_PRESS_8X,
>
> + .temp_coeffs = bmp180_temp_coeffs,
> + .temp_coeffs_type = IIO_VAL_FRACTIONAL,
> + .press_coeffs = bmp180_press_coeffs,
> + .press_coeffs_type = IIO_VAL_FRACTIONAL,
> +
> .chip_config = bmp180_chip_config,
> .read_temp = bmp180_read_temp,
> .read_press = bmp180_read_press,
> diff --git a/drivers/iio/pressure/bmp280.h b/drivers/iio/pressure/bmp280.h
> index 7c30e4d523be..a3d2cd722760 100644
> --- a/drivers/iio/pressure/bmp280.h
> +++ b/drivers/iio/pressure/bmp280.h
> @@ -446,10 +446,17 @@ struct bmp280_chip_info {
> int num_sampling_freq_avail;
> int sampling_freq_default;
>
> + const int *temp_coeffs;
> + const int temp_coeffs_type;
> + const int *press_coeffs;
> + const int press_coeffs_type;
> + const int *humid_coeffs;
> + const int humid_coeffs_type;
> +
> int (*chip_config)(struct bmp280_data *data);
> - int (*read_temp)(struct bmp280_data *data, int *val, int *val2);
> - int (*read_press)(struct bmp280_data *data, int *val, int *val2);
> - int (*read_humid)(struct bmp280_data *data, int *val, int *val2);
> + int (*read_temp)(struct bmp280_data *data, s32 *adc_temp);
> + int (*read_press)(struct bmp280_data *data, u32 *adc_press);
> + int (*read_humid)(struct bmp280_data *data, u32 *adc_humidity);
> int (*read_calib)(struct bmp280_data *data);
> int (*preinit)(struct bmp280_data *data);
> };
> --
> 2.25.1
>

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