Kernel/linux
1
0
Fork 0
mirror of https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git synced 2025-01-01 02:33:57 +00:00
Code Issues Actions Packages Projects Releases Wiki Activity

iio: chemical: bme680: Refactorize reading functions

Browse Source 
The reading of the pressure and humidity value, requires an update of the
t_fine variable which happens by reading the temperature value.

So the bme680_read_{press/humid}() functions of the above sensors are
internally calling the equivalent bme680_read_temp() function in order to
update the t_fine value. By just looking at the code this relation is a
bit hidden and is not easy to understand why those channels are not
independent.

This commit tries to clear these thing a bit by splitting the
bme680_{read/compensate}_{temp/press/humid}() to the following:

i. bme680_read_{temp/press/humid}_adc(): read the raw value from the
sensor.

ii. bme680_calc_t_fine(): calculate the t_fine variable.

iii. bme680_get_t_fine(): get the t_fine variable.

iv. bme680_compensate_{temp/press/humid}(): compensate the adc values and
return the calculated value.

v. bme680_read_{temp/press/humid}(): combine calls of the aforementioned
functions to return the requested value.

Signed-off-by: Vasileios Amoiridis <vassilisamir@gmail.com>
Link: https://patch.msgid.link/20240609233826.330516-16-vassilisamir@gmail.com
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
This commit is contained in:
Vasileios Amoiridis 2024-06-10 01:38:26 +02:00 committed by Jonathan Cameron
parent ed4bb53c46
commit d2651a43f3
1 changed files with 116 additions and 76 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

192
drivers/iio/chemical/bme680_core.c
View File

@ -104,11 +104,6 @@ struct bme680_data {
u8 oversampling_humid;
u16 heater_dur;
u16 heater_temp;
/*
* Carryover value from temperature conversion, used in pressure
* and humidity compensation calculations.
*/
s32 t_fine;
union {
u8 buf[3];
@ -237,6 +232,31 @@ static int bme680_read_calib(struct bme680_data *data,
return 0;
}
static int bme680_read_temp_adc(struct bme680_data *data, u32 *adc_temp)
{
struct device *dev = regmap_get_device(data->regmap);
u32 value_temp;
int ret;
ret = regmap_bulk_read(data->regmap, BME680_REG_TEMP_MSB,
data->buf, BME680_TEMP_NUM_BYTES);
if (ret < 0) {
dev_err(dev, "failed to read temperature\n");
return ret;
}
value_temp = FIELD_GET(BME680_MEAS_TRIM_MASK,
get_unaligned_be24(data->buf));
if (value_temp == BME680_MEAS_SKIPPED) {
/* reading was skipped */
dev_err(dev, "reading temperature skipped\n");
return -EINVAL;
}
*adc_temp = value_temp;
return 0;
}
/*
* Taken from Bosch BME680 API:
* https://github.com/BoschSensortec/BME680_driver/blob/63bb5336/bme680.c#L876
@ -244,12 +264,10 @@ static int bme680_read_calib(struct bme680_data *data,
* Returns temperature measurement in DegC, resolutions is 0.01 DegC. Therefore,
* output value of "3233" represents 32.33 DegC.
*/
static s16 bme680_compensate_temp(struct bme680_data *data,
u32 adc_temp)
static s32 bme680_calc_t_fine(struct bme680_data *data, u32 adc_temp)
{
struct bme680_calib *calib = &data->bme680;
s64 var1, var2, var3;
s16 calc_temp;
/* If the calibration is invalid, attempt to reload it */
if (!calib->par_t2)
@ -259,10 +277,52 @@ static s16 bme680_compensate_temp(struct bme680_data *data,
var2 = (var1 * calib->par_t2) >> 11;
var3 = ((var1 >> 1) * (var1 >> 1)) >> 12;
var3 = (var3 * ((s32)calib->par_t3 << 4)) >> 14;
data->t_fine = var2 + var3;
calc_temp = (data->t_fine * 5 + 128) >> 8;
return var2 + var3; /* t_fine = var2 + var3 */
}
return calc_temp;
static int bme680_get_t_fine(struct bme680_data *data, s32 *t_fine)
{
u32 adc_temp;
int ret;
ret = bme680_read_temp_adc(data, &adc_temp);
if (ret)
return ret;
*t_fine = bme680_calc_t_fine(data, adc_temp);
return 0;
}
static s16 bme680_compensate_temp(struct bme680_data *data,
u32 adc_temp)
{
return (bme680_calc_t_fine(data, adc_temp) * 5 + 128) / 256;
}
static int bme680_read_press_adc(struct bme680_data *data, u32 *adc_press)
{
struct device *dev = regmap_get_device(data->regmap);
u32 value_press;
int ret;
ret = regmap_bulk_read(data->regmap, BME680_REG_PRESS_MSB,
data->buf, BME680_PRESS_NUM_BYTES);
if (ret < 0) {
dev_err(dev, "failed to read pressure\n");
return ret;
}
value_press = FIELD_GET(BME680_MEAS_TRIM_MASK,
get_unaligned_be24(data->buf));
if (value_press == BME680_MEAS_SKIPPED) {
/* reading was skipped */
dev_err(dev, "reading pressure skipped\n");
return -EINVAL;
}
*adc_press = value_press;
return 0;
}
/*
@ -273,12 +333,12 @@ static s16 bme680_compensate_temp(struct bme680_data *data,
* 97356 Pa = 973.56 hPa.
*/
static u32 bme680_compensate_press(struct bme680_data *data,
u32 adc_press)
u32 adc_press, s32 t_fine)
{
struct bme680_calib *calib = &data->bme680;
s32 var1, var2, var3, press_comp;
var1 = (data->t_fine >> 1) - 64000;
var1 = (t_fine >> 1) - 64000;
var2 = ((((var1 >> 2) * (var1 >> 2)) >> 11) * calib->par_p6) >> 2;
var2 = var2 + (var1 * calib->par_p5 << 1);
var2 = (var2 >> 2) + ((s32)calib->par_p4 << 16);
@ -306,6 +366,30 @@ static u32 bme680_compensate_press(struct bme680_data *data,
return press_comp;
}
static int bme680_read_humid_adc(struct bme680_data *data, u32 *adc_humidity)
{
struct device *dev = regmap_get_device(data->regmap);
u32 value_humidity;
int ret;
ret = regmap_bulk_read(data->regmap, BME680_REG_HUMIDITY_MSB,
&data->be16, BME680_HUMID_NUM_BYTES);
if (ret < 0) {
dev_err(dev, "failed to read humidity\n");
return ret;
}
value_humidity = be16_to_cpu(data->be16);
if (value_humidity == BME680_MEAS_SKIPPED) {
/* reading was skipped */
dev_err(dev, "reading humidity skipped\n");
return -EINVAL;
}
*adc_humidity = value_humidity;
return 0;
}
/*
* Taken from Bosch BME680 API:
* https://github.com/BoschSensortec/BME680_driver/blob/63bb5336/bme680.c#L937
@ -314,12 +398,12 @@ static u32 bme680_compensate_press(struct bme680_data *data,
* value of "43215" represents 43.215 %rH.
*/
static u32 bme680_compensate_humid(struct bme680_data *data,
u16 adc_humid)
u16 adc_humid, s32 t_fine)
{
struct bme680_calib *calib = &data->bme680;
s32 var1, var2, var3, var4, var5, var6, temp_scaled, calc_hum;
temp_scaled = (data->t_fine * 5 + 128) >> 8;
temp_scaled = (t_fine * 5 + 128) >> 8;
var1 = (adc_humid - (((s32)calib->par_h1 * 16))) -
(((temp_scaled * calib->par_h3) / 100) >> 1);
var2 = (calib->par_h2 *
@ -567,68 +651,35 @@ static int bme680_gas_config(struct bme680_data *data)
static int bme680_read_temp(struct bme680_data *data, int *val)
{
struct device *dev = regmap_get_device(data->regmap);
int ret;
u32 adc_temp;
s16 comp_temp;
ret = regmap_bulk_read(data->regmap, BME680_REG_TEMP_MSB,
data->buf, BME680_TEMP_NUM_BYTES);
if (ret < 0) {
dev_err(dev, "failed to read temperature\n");
ret = bme680_read_temp_adc(data, &adc_temp);
if (ret)
return ret;
}
adc_temp = FIELD_GET(BME680_MEAS_TRIM_MASK,
get_unaligned_be24(data->buf));
if (adc_temp == BME680_MEAS_SKIPPED) {
/* reading was skipped */
dev_err(dev, "reading temperature skipped\n");
return -EINVAL;
}
comp_temp = bme680_compensate_temp(data, adc_temp);
/*
* val might be NULL if we're called by the read_press/read_humid
* routine which is called to get t_fine value used in
* compensate_press/compensate_humid to get compensated
* pressure/humidity readings.
*/
if (val) {
*val = comp_temp * 10; /* Centidegrees to millidegrees */
return IIO_VAL_INT;
}
return ret;
*val = comp_temp * 10; /* Centidegrees to millidegrees */
return IIO_VAL_INT;
}
static int bme680_read_press(struct bme680_data *data,
int *val, int *val2)
{
struct device *dev = regmap_get_device(data->regmap);
int ret;
u32 adc_press;
s32 t_fine;
/* Read and compensate temperature to get a reading of t_fine */
ret = bme680_read_temp(data, NULL);
if (ret < 0)
ret = bme680_get_t_fine(data, &t_fine);
if (ret)
return ret;
ret = regmap_bulk_read(data->regmap, BME680_REG_PRESS_MSB,
data->buf, BME680_PRESS_NUM_BYTES);
if (ret < 0) {
dev_err(dev, "failed to read pressure\n");
ret = bme680_read_press_adc(data, &adc_press);
if (ret)
return ret;
}
adc_press = FIELD_GET(BME680_MEAS_TRIM_MASK,
get_unaligned_be24(data->buf));
if (adc_press == BME680_MEAS_SKIPPED) {
/* reading was skipped */
dev_err(dev, "reading pressure skipped\n");
return -EINVAL;
}
*val = bme680_compensate_press(data, adc_press);
*val = bme680_compensate_press(data, adc_press, t_fine);
*val2 = 1000;
return IIO_VAL_FRACTIONAL;
}
@ -636,30 +687,19 @@ static int bme680_read_press(struct bme680_data *data,
static int bme680_read_humid(struct bme680_data *data,
int *val, int *val2)
{
struct device *dev = regmap_get_device(data->regmap);
int ret;
u16 adc_humidity;
u32 comp_humidity;
u32 adc_humidity, comp_humidity;
s32 t_fine;
/* Read and compensate temperature to get a reading of t_fine */
ret = bme680_read_temp(data, NULL);
if (ret < 0)
ret = bme680_get_t_fine(data, &t_fine);
if (ret)
return ret;
ret = regmap_bulk_read(data->regmap, BME680_REG_HUMIDITY_MSB,
&data->be16, BME680_HUMID_NUM_BYTES);
if (ret < 0) {
dev_err(dev, "failed to read humidity\n");
ret = bme680_read_humid_adc(data, &adc_humidity);
if (ret)
return ret;
}
adc_humidity = be16_to_cpu(data->be16);
if (adc_humidity == BME680_MEAS_SKIPPED) {
/* reading was skipped */
dev_err(dev, "reading humidity skipped\n");
return -EINVAL;
}
comp_humidity = bme680_compensate_humid(data, adc_humidity);
comp_humidity = bme680_compensate_humid(data, adc_humidity, t_fine);
*val = comp_humidity;
*val2 = 1000;