For BMP18x, BMP28x, BME280, BMP38x the reading of the pressure
value requires an update of the t_fine variable which happens
through reading the temperature value.
So all the bmpxxx_read_press() functions of the above sensors
are internally calling the equivalent bmpxxx_read_temp() function
in order to update the t_fine value. By just looking at the code
this functionality is a bit hidden and is not easy to understand
why those channels are not independent.
This commit tries to clear these things a bit by splitting the
bmpxxx_{read/compensate}_{temp/press/humid}() to the following:
i. bmpxxx_read_{temp/press/humid}_adc(): read the raw value from
the sensor.
ii. bmpxx_calc_t_fine(): calculate the t_fine variable.
iii. bmpxxx_get_t_fine(): get the t_fine variable.
iv. bmpxxx_compensate_{temp/press/humid}(): compensate the adc
values and return the calculated value.
v. bmpxxx_read_{temp/press/humid}(): combine calls of the
aforementioned functions to return the requested value.
Suggested-by: Jonathan Cameron <Jonathan.Cameron@xxxxxxxxxx>
Signed-off-by: Vasileios Amoiridis <vassilisamir@xxxxxxxxx>
---
drivers/iio/pressure/bmp280-core.c | 351 ++++++++++++++++++-----------
drivers/iio/pressure/bmp280.h | 6 -
2 files changed, 221 insertions(+), 136 deletions(-)
diff --git a/drivers/iio/pressure/bmp280-core.c b/drivers/iio/pressure/bmp280-core.c
index 8290028824e9..5ebce38e99f6 100644
--- a/drivers/iio/pressure/bmp280-core.c
+++ b/drivers/iio/pressure/bmp280-core.c
@@ -288,13 +288,33 @@ static int bme280_read_calib(struct bmp280_data *data)
*
* Taken from BME280 datasheet, Section 4.2.3, "Compensation formula".
*/
+static int bme280_read_humid_adc(struct bmp280_data *data, s32 *adc_humidity)
+{
+ int ret;
+
+ ret = regmap_bulk_read(data->regmap, BME280_REG_HUMIDITY_MSB,
+ &data->be16, sizeof(data->be16));
+ if (ret < 0) {
+ dev_err(data->dev, "failed to read humidity\n");
+ return ret;
+ }
+
+ *adc_humidity = be16_to_cpu(data->be16);
+ if (*adc_humidity == BMP280_HUMIDITY_SKIPPED) {
+ dev_err(data->dev, "reading humidity skipped\n");
+ return -EIO;
+ }
+
+ return 0;
+}
+
static u32 bme280_compensate_humidity(struct bmp280_data *data,
- s32 adc_humidity)
+ s32 adc_humidity, s32 t_fine)
{
struct bmp280_calib *calib = &data->calib.bmp280;
s32 var;
- var = ((s32)data->t_fine) - (s32)76800;
+ var = ((s32)t_fine) - (s32)76800;
var = ((((adc_humidity << 14) - (calib->H4 << 20) - (calib->H5 * var))
+ (s32)16384) >> 15) * (((((((var * calib->H6) >> 10)
* (((var * (s32)calib->H3) >> 11) + (s32)32768)) >> 10)
@@ -313,8 +333,27 @@ static u32 bme280_compensate_humidity(struct bmp280_data *data,
*
* Taken from datasheet, Section 3.11.3, "Compensation formula".
*/
-static s32 bmp280_compensate_temp(struct bmp280_data *data,
- s32 adc_temp)
+static int bmp280_read_temp_adc(struct bmp280_data *data, s32 *adc_temp)
+{
+ int ret;
+
+ ret = regmap_bulk_read(data->regmap, BMP280_REG_TEMP_MSB,
+ data->buf, sizeof(data->buf));
+ if (ret < 0) {
+ dev_err(data->dev, "failed to read temperature\n");
+ return ret;
+ }
+
+ *adc_temp = FIELD_GET(BMP280_MEAS_TRIM_MASK, get_unaligned_be24(data->buf));
+ if (*adc_temp == BMP280_TEMP_SKIPPED) {
+ dev_err(data->dev, "reading temperature skipped\n");
+ return -EIO;
+ }
+
+ return 0;
+}
+
+static s32 bmp280_calc_t_fine(struct bmp280_data *data, s32 adc_temp)
{
struct bmp280_calib *calib = &data->calib.bmp280;
s32 var1, var2;
@@ -324,9 +363,26 @@ static s32 bmp280_compensate_temp(struct bmp280_data *data,
var2 = (((((adc_temp >> 4) - ((s32)calib->T1)) *
((adc_temp >> 4) - ((s32)calib->T1))) >> 12) *
((s32)calib->T3)) >> 14;
- data->t_fine = var1 + var2;
+ return var1 + var2; /* t_fine = var1 + var2 */
+}
+
+static int bmp280_get_t_fine(struct bmp280_data *data, s32 *t_fine)
+{
+ s32 adc_temp;
+ int ret;
+
+ ret = bmp280_read_temp_adc(data, &adc_temp);
+ if (ret < 0)
+ return ret;
+
+ *t_fine = bmp280_calc_t_fine(data, adc_temp);
- return (data->t_fine * 5 + 128) >> 8;
+ return 0;
+}
+
+static s32 bmp280_compensate_temp(struct bmp280_data *data, s32 adc_temp)
+{
+ return (bmp280_calc_t_fine(data, adc_temp) * 5 + 128) / 256;
}
/*
@@ -336,13 +392,33 @@ static s32 bmp280_compensate_temp(struct bmp280_data *data,
*
* Taken from datasheet, Section 3.11.3, "Compensation formula".
*/
+static int bmp280_read_press_adc(struct bmp280_data *data, s32 *adc_press)
+{
+ int ret;
+
+ ret = regmap_bulk_read(data->regmap, BMP280_REG_PRESS_MSB,
+ data->buf, sizeof(data->buf));
+ if (ret < 0) {
+ dev_err(data->dev, "failed to read pressure\n");
+ return ret;
+ }
+
+ *adc_press = FIELD_GET(BMP280_MEAS_TRIM_MASK, get_unaligned_be24(data->buf));
+ if (*adc_press == BMP280_PRESS_SKIPPED) {
+ dev_err(data->dev, "reading pressure skipped\n");
+ return -EIO;
+ }
+
+ return 0;
+}
+
static u32 bmp280_compensate_press(struct bmp280_data *data,
- s32 adc_press)
+ s32 adc_press, s32 t_fine)
{
struct bmp280_calib *calib = &data->calib.bmp280;
s64 var1, var2, p;
- var1 = ((s64)data->t_fine) - 128000;
+ var1 = ((s64)t_fine) - 128000;
var2 = var1 * var1 * (s64)calib->P6;
var2 += (var1 * (s64)calib->P5) << 17;
var2 += ((s64)calib->P4) << 35;
@@ -368,60 +444,35 @@ static int bmp280_read_temp(struct bmp280_data *data,
s32 adc_temp, comp_temp;
int ret;
- ret = regmap_bulk_read(data->regmap, BMP280_REG_TEMP_MSB,
- data->buf, sizeof(data->buf));
- if (ret < 0) {
- dev_err(data->dev, "failed to read temperature\n");
+ ret = bmp280_read_temp_adc(data, &adc_temp);
+ if (ret < 0)
return ret;
- }
- adc_temp = FIELD_GET(BMP280_MEAS_TRIM_MASK, get_unaligned_be24(data->buf));
- if (adc_temp == BMP280_TEMP_SKIPPED) {
- /* reading was skipped */
- dev_err(data->dev, "reading temperature skipped\n");
- return -EIO;
- }
comp_temp = bmp280_compensate_temp(data, adc_temp);
- /*
- * val might be NULL if we're called by the read_press routine,
- * who only cares about the carry over t_fine value.
- */
- if (val) {
- *val = comp_temp * 10;
- return IIO_VAL_INT;
- }
-
- return 0;
+ /* IIO units are in milli Celsius */
+ *val = comp_temp * 10;
+ return IIO_VAL_INT;
}
static int bmp280_read_press(struct bmp280_data *data,
int *val, int *val2)
{
+ s32 adc_press, t_fine;
u32 comp_press;
- s32 adc_press;
int ret;
- /* Read and compensate temperature so we get a reading of t_fine. */
- ret = bmp280_read_temp(data, NULL, NULL);
+ ret = bmp280_get_t_fine(data, &t_fine);
if (ret < 0)
return ret;
- ret = regmap_bulk_read(data->regmap, BMP280_REG_PRESS_MSB,
- data->buf, sizeof(data->buf));
- if (ret < 0) {
- dev_err(data->dev, "failed to read pressure\n");
+ ret = bmp280_read_press_adc(data, &adc_press);
+ if (ret < 0)
return ret;
- }
- adc_press = FIELD_GET(BMP280_MEAS_TRIM_MASK, get_unaligned_be24(data->buf));
- if (adc_press == BMP280_PRESS_SKIPPED) {
- /* reading was skipped */
- dev_err(data->dev, "reading pressure skipped\n");
- return -EIO;
- }
- comp_press = bmp280_compensate_press(data, adc_press);
+ comp_press = bmp280_compensate_press(data, adc_press, t_fine);
+ /* IIO units are in kPa */
*val = comp_press;
*val2 = 256000;
@@ -430,30 +481,21 @@ static int bmp280_read_press(struct bmp280_data *data,
static int bme280_read_humid(struct bmp280_data *data, int *val, int *val2)
{
+ s32 adc_humidity, t_fine;
u32 comp_humidity;
- s32 adc_humidity;
int ret;
- /* Read and compensate temperature so we get a reading of t_fine. */
- ret = bmp280_read_temp(data, NULL, NULL);
+ ret = bmp280_get_t_fine(data, &t_fine);
if (ret < 0)
return ret;
- ret = regmap_bulk_read(data->regmap, BME280_REG_HUMIDITY_MSB,
- &data->be16, sizeof(data->be16));
- if (ret < 0) {
- dev_err(data->dev, "failed to read humidity\n");
+ ret = bme280_read_humid_adc(data, &adc_humidity);
+ if (ret < 0)
return ret;
- }
- adc_humidity = be16_to_cpu(data->be16);
- if (adc_humidity == BMP280_HUMIDITY_SKIPPED) {
- /* reading was skipped */
- dev_err(data->dev, "reading humidity skipped\n");
- return -EIO;
- }
- comp_humidity = bme280_compensate_humidity(data, adc_humidity);
+ comp_humidity = bme280_compensate_humidity(data, adc_humidity, t_fine);
+ /* IIO units are in 1000 * % */
*val = comp_humidity * 1000 / 1024;
return IIO_VAL_INT;
@@ -930,9 +972,29 @@ static int bmp380_cmd(struct bmp280_data *data, u8 cmd)
* Taken from datasheet, Section Appendix 9, "Compensation formula" and repo
* https://github.com/BoschSensortec/BMP3-Sensor-API.
*/
-static s32 bmp380_compensate_temp(struct bmp280_data *data, u32 adc_temp)
+static int bmp380_read_temp_adc(struct bmp280_data *data, u32 *adc_temp)
+{
+ int ret;
+
+ ret = regmap_bulk_read(data->regmap, BMP380_REG_TEMP_XLSB,
+ data->buf, sizeof(data->buf));
+ if (ret < 0) {
+ dev_err(data->dev, "failed to read temperature\n");
+ return ret;
+ }
+
+ *adc_temp = get_unaligned_le24(data->buf);
+ if (*adc_temp == BMP380_TEMP_SKIPPED) {
+ dev_err(data->dev, "reading temperature skipped\n");
+ return -EIO;
+ }
+
+ return 0;
+}
+
+static s32 bmp380_calc_t_fine(struct bmp280_data *data, u32 adc_temp)
{
- s64 var1, var2, var3, var4, var5, var6, comp_temp;
+ s64 var1, var2, var3, var4, var5, var6;
struct bmp380_calib *calib = &data->calib.bmp380;
var1 = ((s64) adc_temp) - (((s64) calib->T1) << 8);
@@ -941,7 +1003,29 @@ static s32 bmp380_compensate_temp(struct bmp280_data *data, u32 adc_temp)
var4 = var3 * ((s64) calib->T3);
var5 = (var2 << 18) + var4;
var6 = var5 >> 32;
- data->t_fine = (s32) var6;
+ return (s32) var6; /* t_fine = var6 */
+}
+
+static int bmp380_get_t_fine(struct bmp280_data *data, s32 *t_fine)
+{
+ s32 adc_temp;
+ int ret;
+
+ ret = bmp380_read_temp_adc(data, &adc_temp);
+ if (ret < 0)
+ return ret;
+
+ *t_fine = bmp380_calc_t_fine(data, adc_temp);
+
+ return 0;
+}
+
+static int bmp380_compensate_temp(struct bmp280_data *data, u32 adc_temp)
+{
+ s64 comp_temp;
+ s32 var6;
+
+ var6 = bmp380_calc_t_fine(data, adc_temp);
comp_temp = (var6 * 25) >> 14;
comp_temp = clamp_val(comp_temp, BMP380_MIN_TEMP, BMP380_MAX_TEMP);
@@ -955,27 +1039,48 @@ static s32 bmp380_compensate_temp(struct bmp280_data *data, u32 adc_temp)
* Taken from datasheet, Section 9.3. "Pressure compensation" and repository
* https://github.com/BoschSensortec/BMP3-Sensor-API.
*/
-static u32 bmp380_compensate_press(struct bmp280_data *data, u32 adc_press)
+static int bmp380_read_press_adc(struct bmp280_data *data, u32 *adc_press)
+{
+ int ret;
+
+ ret = regmap_bulk_read(data->regmap, BMP380_REG_PRESS_XLSB,
+ data->buf, sizeof(data->buf));
+ if (ret < 0) {
+ dev_err(data->dev, "failed to read pressure\n");
+ return ret;
+ }
+
+ *adc_press = get_unaligned_le24(data->buf);
+ if (*adc_press == BMP380_PRESS_SKIPPED) {
+ dev_err(data->dev, "reading pressure skipped\n");
+ return -EIO;
+ }
+
+ return 0;
+}
+
+static u32 bmp380_compensate_press(struct bmp280_data *data,
+ u32 adc_press, s32 t_fine)
{
s64 var1, var2, var3, var4, var5, var6, offset, sensitivity;
struct bmp380_calib *calib = &data->calib.bmp380;
u32 comp_press;
- var1 = (s64)data->t_fine * (s64)data->t_fine;
+ var1 = (s64)t_fine * (s64)t_fine;
var2 = var1 >> 6;
- var3 = (var2 * ((s64) data->t_fine)) >> 8;
+ var3 = (var2 * ((s64) t_fine)) >> 8;
var4 = ((s64)calib->P8 * var3) >> 5;
var5 = ((s64)calib->P7 * var1) << 4;
- var6 = ((s64)calib->P6 * (s64)data->t_fine) << 22;
+ var6 = ((s64)calib->P6 * (s64)t_fine) << 22;
offset = ((s64)calib->P5 << 47) + var4 + var5 + var6;
var2 = ((s64)calib->P4 * var3) >> 5;
var4 = ((s64)calib->P3 * var1) << 2;
var5 = ((s64)calib->P2 - ((s64)1 << 14)) *
- ((s64)data->t_fine << 21);
+ ((s64)t_fine << 21);
sensitivity = (((s64) calib->P1 - ((s64) 1 << 14)) << 46) +
var2 + var4 + var5;
var1 = (sensitivity >> 24) * (s64)adc_press;
- var2 = (s64)calib->P10 * (s64)data->t_fine;
+ var2 = (s64)calib->P10 * (s64)t_fine;
var3 = var2 + ((s64)calib->P9 << 16);
var4 = (var3 * (s64)adc_press) >> 13;
@@ -1001,60 +1106,34 @@ static int bmp380_read_temp(struct bmp280_data *data, int *val, int *val2)
u32 adc_temp;
int ret;
- ret = regmap_bulk_read(data->regmap, BMP380_REG_TEMP_XLSB,
- data->buf, sizeof(data->buf));
- if (ret < 0) {
- dev_err(data->dev, "failed to read temperature\n");
+ ret = bmp380_read_temp_adc(data, &adc_temp);
+ if (ret < 0)
return ret;
- }
- adc_temp = get_unaligned_le24(data->buf);
- if (adc_temp == BMP380_TEMP_SKIPPED) {
- dev_err(data->dev, "reading temperature skipped\n");
- return -EIO;
- }
comp_temp = bmp380_compensate_temp(data, adc_temp);
- /*
- * Val might be NULL if we're called by the read_press routine,
- * who only cares about the carry over t_fine value.
- */
- if (val) {
- /* IIO reports temperatures in milli Celsius */
- *val = comp_temp * 10;
- return IIO_VAL_INT;
- }
-
- return 0;
+ /* IIO units are in milli Celsius */
+ *val = comp_temp * 10;
+ return IIO_VAL_INT;
}
static int bmp380_read_press(struct bmp280_data *data, int *val, int *val2)
{
- s32 comp_press;
- u32 adc_press;
+ u32 adc_press, comp_press, t_fine;
int ret;
- /* Read and compensate for temperature so we get a reading of t_fine */
- ret = bmp380_read_temp(data, NULL, NULL);
+ ret = bmp380_get_t_fine(data, &t_fine);
if (ret < 0)
return ret;
- ret = regmap_bulk_read(data->regmap, BMP380_REG_PRESS_XLSB,
- data->buf, sizeof(data->buf));
- if (ret < 0) {
- dev_err(data->dev, "failed to read pressure\n");
+ ret = bmp380_read_press_adc(data, &adc_press);
+ if (ret < 0)
return ret;
- }
- adc_press = get_unaligned_le24(data->buf);
- if (adc_press == BMP380_PRESS_SKIPPED) {
- dev_err(data->dev, "reading pressure skipped\n");
- return -EIO;
- }
- comp_press = bmp380_compensate_press(data, adc_press);
+ comp_press = bmp380_compensate_press(data, adc_press, t_fine);
+ /* IIO units are in kPa */
*val = comp_press;
- /* Compensated pressure is in cPa (centipascals) */
*val2 = 100000;
return IIO_VAL_FRACTIONAL;
@@ -1826,7 +1905,7 @@ static int bmp180_wait_for_eoc(struct bmp280_data *data, u8 ctrl_meas)
return 0;
}
-static int bmp180_read_adc_temp(struct bmp280_data *data, int *val)
+static int bmp180_read_temp_adc(struct bmp280_data *data, s32 *adc_temp)
{
int ret;
@@ -1843,7 +1922,7 @@ static int bmp180_read_adc_temp(struct bmp280_data *data, int *val)
return ret;
}
- *val = be16_to_cpu(data->be16);
+ *adc_temp = be16_to_cpu(data->be16);
return 0;
}
@@ -1893,16 +1972,34 @@ static int bmp180_read_calib(struct bmp280_data *data)
*
* Taken from datasheet, Section 3.5, "Calculating pressure and temperature".
*/
-static s32 bmp180_compensate_temp(struct bmp280_data *data, s32 adc_temp)
+
+static s32 bmp180_calc_t_fine(struct bmp280_data *data, s32 adc_temp)
{
struct bmp180_calib *calib = &data->calib.bmp180;
s32 x1, x2;
x1 = ((adc_temp - calib->AC6) * calib->AC5) >> 15;
x2 = (calib->MC << 11) / (x1 + calib->MD);
- data->t_fine = x1 + x2;
+ return x1 + x2; /* t_fine = x1 + x2; */
+}
+
+static int bmp180_get_t_fine(struct bmp280_data *data, s32 *t_fine)
+{
+ s32 adc_temp;
+ int ret;
+
+ ret = bmp180_read_temp_adc(data, &adc_temp);
+ if (ret < 0)
+ return ret;
+
+ *t_fine = bmp180_calc_t_fine(data, adc_temp);
- return (data->t_fine + 8) >> 4;
+ return 0;
+}
+
+static s32 bmp180_compensate_temp(struct bmp280_data *data, s32 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)
@@ -1910,25 +2007,18 @@ static int bmp180_read_temp(struct bmp280_data *data, int *val, int *val2)
s32 adc_temp, comp_temp;
int ret;
- ret = bmp180_read_adc_temp(data, &adc_temp);
+ ret = bmp180_read_temp_adc(data, &adc_temp);
if (ret < 0)
return ret;
comp_temp = bmp180_compensate_temp(data, adc_temp);
- /*
- * val might be NULL if we're called by the read_press routine,
- * who only cares about the carry over t_fine value.
- */
- if (val) {
- *val = comp_temp * 100;
- return IIO_VAL_INT;
- }
-
- return 0;
+ /* IIO units are in milli Celsius */
+ *val = comp_temp * 100;
+ return IIO_VAL_INT;
}
-static int bmp180_read_adc_press(struct bmp280_data *data, int *val)
+static int bmp180_read_press_adc(struct bmp280_data *data, s32 *adc_press)
{
u8 oss = data->oversampling_press;
int ret;
@@ -1947,7 +2037,7 @@ static int bmp180_read_adc_press(struct bmp280_data *data, int *val)
return ret;
}
- *val = get_unaligned_be24(data->buf) >> (8 - oss);
+ *adc_press = get_unaligned_be24(data->buf) >> (8 - oss);
return 0;
}
@@ -1957,7 +2047,8 @@ static int bmp180_read_adc_press(struct bmp280_data *data, int *val)
*
* Taken from datasheet, Section 3.5, "Calculating pressure and temperature".
*/
-static u32 bmp180_compensate_press(struct bmp280_data *data, s32 adc_press)
+static u32 bmp180_compensate_press(struct bmp280_data *data, s32 adc_press,
+ s32 t_fine)
{
struct bmp180_calib *calib = &data->calib.bmp180;
s32 oss = data->oversampling_press;
@@ -1965,7 +2056,7 @@ static u32 bmp180_compensate_press(struct bmp280_data *data, s32 adc_press)
s32 b3, b6;
u32 b4, b7;
- b6 = data->t_fine - 4000;
+ b6 = t_fine - 4000;
x1 = (calib->B2 * (b6 * b6 >> 12)) >> 11;
x2 = calib->AC2 * b6 >> 11;
x3 = x1 + x2;
@@ -1989,21 +2080,21 @@ static u32 bmp180_compensate_press(struct bmp280_data *data, s32 adc_press)
static int bmp180_read_press(struct bmp280_data *data, int *val, int *val2)
{
+ s32 adc_press, t_fine;
u32 comp_press;
- s32 adc_press;
int ret;
- /* Read and compensate temperature so we get a reading of t_fine. */
- ret = bmp180_read_temp(data, NULL, NULL);
+ ret = bmp180_get_t_fine(data, &t_fine);
if (ret < 0)
return ret;
- ret = bmp180_read_adc_press(data, &adc_press);
+ ret = bmp180_read_press_adc(data, &adc_press);
if (ret < 0)
return ret;
- comp_press = bmp180_compensate_press(data, adc_press);
+ comp_press = bmp180_compensate_press(data, adc_press, t_fine);
+ /* IIO units are in kPa */
*val = comp_press;
*val2 = 1000;
diff --git a/drivers/iio/pressure/bmp280.h b/drivers/iio/pressure/bmp280.h
index fe4d3f127954..7c30e4d523be 100644
--- a/drivers/iio/pressure/bmp280.h
+++ b/drivers/iio/pressure/bmp280.h
@@ -397,12 +397,6 @@ struct bmp280_data {
*/
int sampling_freq;
- /*
- * Carryover value from temperature conversion, used in pressure
- * calculation.
- */
- s32 t_fine;
-
/*
* DMA (thus cache coherency maintenance) may require the
* transfer buffers to live in their own cache lines.
--
2.25.1
