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Thu, 20 Aug 2026 07:15:05 -0700 (PDT) From: Louis Adamian To: Jonathan Cameron , David Lechner , =?UTF-8?q?Nuno=20S=C3=A1?= , Andy Shevchenko Cc: Louis Adamian , linux-iio@vger.kernel.org, linux-kernel@vger.kernel.org Subject: [PATCH v3 4/5] iio: pressure: ms5637: Parameterise second order temperature compensation Date: Thu, 20 Aug 2026 10:12:19 -0400 Message-ID: <20260820141224.23730-5-adamianlouis@gmail.com> X-Mailer: git-send-email 2.55.0 In-Reply-To: <20260820141224.23730-1-adamianlouis@gmail.com> References: <20260820141224.23730-1-adamianlouis@gmail.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit The temperature compensation formula is shared across these sensors but with different constants. Add ms_tp_comp_consts to capture these per-device differences. Add pressure variant specific pressure scale variable. No functional change intended. IIO_VAL_FRACTIONAL prints 3 more decimal places than IIO_VAL_INT_PLUS_MICRO, giving in_pressure_input 3 more trailing zeros. Signed-off-by: Louis Adamian --- .../iio/common/ms_sensors/ms_sensors_i2c.c | 61 ++++++++++++------- .../iio/common/ms_sensors/ms_sensors_i2c.h | 48 +++++++++++++++ drivers/iio/pressure/ms5637.c | 61 ++++++++++++++++--- 3 files changed, 140 insertions(+), 30 deletions(-) diff --git a/drivers/iio/common/ms_sensors/ms_sensors_i2c.c b/drivers/iio/common/ms_sensors/ms_sensors_i2c.c index f9dc7c7468c1..20f019ae51fd 100644 --- a/drivers/iio/common/ms_sensors/ms_sensors_i2c.c +++ b/drivers/iio/common/ms_sensors/ms_sensors_i2c.c @@ -604,6 +604,38 @@ int ms_sensors_tp_read_prom(struct ms_tp_dev *dev_data) } EXPORT_SYMBOL_NS(ms_sensors_tp_read_prom, "IIO_MEAS_SPEC_SENSORS"); +/* apply second order temperature compensation */ +static void ms_tp_compensate(const struct ms_tp_comp_consts *c, + s32 temp, s32 dt, s64 *t2, s64 *off2, s64 *sens2) +{ + s64 tmp; + + if (temp < 2000) { + tmp = temp - 2000; + *t2 = (c->low_t2_multiplier * ((s64)dt * (s64)dt)) >> + c->low_t2_shift; + *off2 = (c->low_off2_multiplier * tmp * tmp) >> + c->low_off2_shift; + *sens2 = (c->low_sens2_multiplier * tmp * tmp) >> + c->low_sens2_shift; + + if (temp < -1500) { + tmp = temp + 1500; + *off2 += c->vlow_off2_multiplier * tmp * tmp; + *sens2 += c->vlow_sens2_multiplier * tmp * tmp; + } + } else { + *sens2 = 0; + if (c->has_vhigh_temp && temp > 4500) + *sens2 -= (((s64)temp - 4500) * ((s64)temp - 4500)) >> 3; + + *t2 = (c->high_t2_multiplier * ((s64)dt * (s64)dt)) >> c->high_t2_shift; + *off2 = (c->high_off2_multiplier * + ((s64)temp - 2000) * ((s64)temp - 2000)) >> + c->high_off2_shift; + } +} + /** * ms_sensors_read_temp_and_pressure() - read temp and pressure * @dev_data: pointer to temperature/pressure device data @@ -619,6 +651,7 @@ int ms_sensors_read_temp_and_pressure(struct ms_tp_dev *dev_data, int *temperature, unsigned int *pressure) { + const struct ms_tp_comp_consts *c = dev_data->data->comp_consts; int ret; u32 t_adc, p_adc; s32 dt, temp; @@ -654,37 +687,21 @@ int ms_sensors_read_temp_and_pressure(struct ms_tp_dev *dev_data, /* Actual temperature = 2000 + dT * TEMPSENS */ temp = 2000 + (((s64)dt * prom[6]) >> 23); - /* Second order temperature compensation */ - if (temp < 2000) { - s64 tmp = (s64)temp - 2000; - - t2 = (3 * ((s64)dt * (s64)dt)) >> 33; - off2 = (61 * tmp * tmp) >> 4; - sens2 = (29 * tmp * tmp) >> 4; - - if (temp < -1500) { - s64 tmp = (s64)temp + 1500; - - off2 += 17 * tmp * tmp; - sens2 += 9 * tmp * tmp; - } - } else { - t2 = (5 * ((s64)dt * (s64)dt)) >> 38; - off2 = 0; - sens2 = 0; - } + ms_tp_compensate(c, temp, dt, &t2, &off2, &sens2); /* OFF = OFF_T1 + TCO * dT */ - off = (((s64)prom[2]) << 17) + ((((s64)prom[4]) * (s64)dt) >> 6); + off = (((s64)prom[2]) << c->off_t1_shift) + + ((((s64)prom[4]) * (s64)dt) >> c->off_shift); off -= off2; /* Sensitivity at actual temperature = SENS_T1 + TCS * dT */ - sens = (((s64)prom[1]) << 16) + (((s64)prom[3] * dt) >> 7); + sens = (((s64)prom[1]) << c->sens_t1_shift) + + (((s64)prom[3] * dt) >> c->sens_shift); sens -= sens2; /* Temperature compensated pressure = D1 * SENS - OFF */ *temperature = (temp - t2) * 10; - *pressure = (u32)(((((s64)p_adc * sens) >> 21) - off) >> 15); + *pressure = (u32)(((((s64)p_adc * sens) >> c->press_sens_shift) - off) >> c->press_shift); return 0; } diff --git a/drivers/iio/common/ms_sensors/ms_sensors_i2c.h b/drivers/iio/common/ms_sensors/ms_sensors_i2c.h index d9898098c066..e6e64111f2e7 100644 --- a/drivers/iio/common/ms_sensors/ms_sensors_i2c.h +++ b/drivers/iio/common/ms_sensors/ms_sensors_i2c.h @@ -35,14 +35,62 @@ struct ms_tp_hw_data { u8 max_res_index; }; +/** + * struct ms_tp_comp_consts - Temperature compensation constants + * @press_scale: pressure scale + * @high_t2_multiplier: multiplier for t2 in high temperature state + * @high_t2_shift: bit shift for t2 in high temperature state + * @high_off2_multiplier: multiplier for off2 in high temperature state + * @high_off2_shift: bit shift for off2 in high temperature state + * @low_t2_multiplier: multiplier for t2 in low temperature state + * @low_t2_shift: bit shift for t2 in low temperature state + * @low_off2_multiplier: multiplier for off2 in low temperature state + * @low_off2_shift: bit shift for off2 in low temperature state + * @low_sens2_multiplier: multiplier for sens2 in low temperature state + * @low_sens2_shift: bit shift for sens2 in low temperature state + * @vlow_off2_multiplier: multiplier for value added to off2 in very low temperature state + * @vlow_sens2_multiplier: multiplier for value added to sens2 in very low temperature state + * @has_vhigh_temp: has very high temperature compensation logic + * @off_t1_shift: temperature offset t1 bit shift + * @off_shift: temperature offset shift + * @sens_t1_shift: temperature sensitivity t1 shift + * @sens_shift: temperature sensitivity shift + * @press_sens_shift: pressure sensitivity shift + * @press_shift: pressure shift + */ +struct ms_tp_comp_consts { + u32 press_scale; + u8 high_t2_multiplier; + u8 high_t2_shift; + u8 high_off2_multiplier; + u8 high_off2_shift; + u8 low_t2_multiplier; + u8 low_t2_shift; + u8 low_off2_multiplier; + u8 low_off2_shift; + u8 low_sens2_multiplier; + u8 low_sens2_shift; + u8 vlow_off2_multiplier; + u8 vlow_sens2_multiplier; + bool has_vhigh_temp; + u8 off_t1_shift; + u8 off_shift; + u8 sens_t1_shift; + u8 sens_shift; + u8 press_sens_shift; + u8 press_shift; +}; + /** * struct ms_tp_data - Temperature/Pressure sensor data * @name: Device name * @hw: Sensor hardware data + * @comp_consts: Temperature compensation constants */ struct ms_tp_data { const char *name; const struct ms_tp_hw_data *hw; + const struct ms_tp_comp_consts *comp_consts; }; /** diff --git a/drivers/iio/pressure/ms5637.c b/drivers/iio/pressure/ms5637.c index 6009d87f3d4c..359f3a8e79b2 100644 --- a/drivers/iio/pressure/ms5637.c +++ b/drivers/iio/pressure/ms5637.c @@ -67,10 +67,9 @@ static int ms5637_read_raw(struct iio_dev *indio_dev, return IIO_VAL_INT; case IIO_PRESSURE: /* in kPa */ - *val = pressure / 1000; - *val2 = (pressure % 1000) * 1000; - - return IIO_VAL_INT_PLUS_MICRO; + *val = pressure; + *val2 = dev_data->data->comp_consts->press_scale; + return IIO_VAL_FRACTIONAL; default: return -EINVAL; } @@ -195,17 +194,63 @@ static const struct ms_tp_hw_data ms5803_hw_data = { .max_res_index = 4 }; -static const struct ms_tp_data ms5637_data = { .name = "ms5637", .hw = &ms5637_hw_data }; +/* + * MS5637-02BA03 compensation constants + * Datasheet: https://www.te.com/commerce/DocumentDelivery/DDEController?Action=showdoc&DocId=Data+Sheet%7FMS5637-02BA03%7FB1%7Fpdf%7FEnglish%7FENG_DS_MS5637-02BA03_B1.pdf + * Pages: 7-8 + * Sections: Pressure and Temperature Calculation, Second Order Temperature Compensation + */ +static const struct ms_tp_comp_consts ms5637_02_consts = { + .press_scale = 1000, + .high_t2_multiplier = 5, + .high_t2_shift = 38, + .high_off2_multiplier = 0, + .high_off2_shift = 0, + .low_t2_multiplier = 3, + .low_t2_shift = 33, + .low_off2_multiplier = 61, + .low_off2_shift = 4, + .low_sens2_multiplier = 29, + .low_sens2_shift = 4, + .vlow_off2_multiplier = 17, + .vlow_sens2_multiplier = 9, + .has_vhigh_temp = false, + .off_t1_shift = 17, + .off_shift = 6, + .sens_t1_shift = 16, + .sens_shift = 7, + .press_sens_shift = 21, + .press_shift = 15, +}; + +static const struct ms_tp_data ms5637_data = { + .name = "ms5637", + .hw = &ms5637_hw_data, + .comp_consts = &ms5637_02_consts, +}; -static const struct ms_tp_data ms5803_data = { .name = "ms5803", .hw = &ms5803_hw_data }; +static const struct ms_tp_data ms5803_data = { + .name = "ms5803", + .hw = &ms5803_hw_data, + .comp_consts = &ms5637_02_consts, +}; -static const struct ms_tp_data ms5805_data = { .name = "ms5805", .hw = &ms5637_hw_data }; +static const struct ms_tp_data ms5805_data = { + .name = "ms5805", + .hw = &ms5637_hw_data, + .comp_consts = &ms5637_02_consts, +}; -static const struct ms_tp_data ms5837_data = { .name = "ms5837", .hw = &ms5637_hw_data }; +static const struct ms_tp_data ms5837_data = { + .name = "ms5837", + .hw = &ms5637_hw_data, + .comp_consts = &ms5637_02_consts, +}; static const struct ms_tp_data ms8607_data = { .name = "ms8607-temppressure", .hw = &ms5637_hw_data, + .comp_consts = &ms5637_02_consts, }; static const struct i2c_device_id ms5637_id[] = { -- 2.55.0