diff options
| -rw-r--r-- | drivers/iio/magnetometer/yamaha-yas530.c | 99 |
1 files changed, 76 insertions, 23 deletions
diff --git a/drivers/iio/magnetometer/yamaha-yas530.c b/drivers/iio/magnetometer/yamaha-yas530.c index 199d83013e6f..6296ea3140ef 100644 --- a/drivers/iio/magnetometer/yamaha-yas530.c +++ b/drivers/iio/magnetometer/yamaha-yas530.c @@ -77,6 +77,7 @@ #define YAS530_DATA_BITS 12 #define YAS530_DATA_CENTER BIT(YAS530_DATA_BITS - 1) #define YAS530_DATA_OVERFLOW (BIT(YAS530_DATA_BITS) - 1) +#define YAS530_20DEGREES 182 /* Counts starting at -62 °C */ #define YAS532_DEVICE_ID 0x02 /* YAS532/YAS533 (MS-3R/F) */ #define YAS532_VERSION_AB 0 /* YAS532/533 AB (MS-3R/F AB) */ @@ -88,7 +89,7 @@ #define YAS532_DATA_BITS 13 #define YAS532_DATA_CENTER BIT(YAS532_DATA_BITS - 1) #define YAS532_DATA_OVERFLOW (BIT(YAS532_DATA_BITS) - 1) -#define YAS532_20DEGREES 390 /* Looks like Kelvin */ +#define YAS532_20DEGREES 390 /* Counts starting at -50 °C */ /* These variant IDs are known from code dumps */ #define YAS537_DEVICE_ID 0x07 /* YAS537 (MS-3T) */ @@ -314,7 +315,7 @@ static s32 yas5xx_linearize(struct yas5xx *yas5xx, u16 val, int axis) static int yas5xx_get_measure(struct yas5xx *yas5xx, s32 *to, s32 *xo, s32 *yo, s32 *zo) { struct yas5xx_calibration *c = &yas5xx->calibration; - u16 t, x, y1, y2; + u16 t_ref, t, x, y1, y2; /* These are "signed x, signed y1 etc */ s32 sx, sy1, sy2, sy, sz; int ret; @@ -329,16 +330,46 @@ static int yas5xx_get_measure(struct yas5xx *yas5xx, s32 *to, s32 *xo, s32 *yo, sy1 = yas5xx_linearize(yas5xx, y1, 1); sy2 = yas5xx_linearize(yas5xx, y2, 2); - /* - * Temperature compensation for x, y1, y2 respectively: - * - * Cx * t - * x' = x - ------ - * 100 - */ - sx = sx - (c->Cx * t) / 100; - sy1 = sy1 - (c->Cy1 * t) / 100; - sy2 = sy2 - (c->Cy2 * t) / 100; + /* Set the temperature reference value (unit: counts) */ + switch (yas5xx->devid) { + case YAS530_DEVICE_ID: + t_ref = YAS530_20DEGREES; + break; + case YAS532_DEVICE_ID: + t_ref = YAS532_20DEGREES; + break; + default: + dev_err(yas5xx->dev, "unknown device type\n"); + return -EINVAL; + } + + /* Temperature compensation for x, y1, y2 respectively */ + if (yas5xx->devid == YAS532_DEVICE_ID && + yas5xx->version == YAS532_VERSION_AC) { + /* + * YAS532 version AC uses the temperature deviation as a + * multiplier. + * + * Cx * (t - t_ref) + * x' = x - ---------------- + * 100 + */ + sx = sx - (c->Cx * (t - t_ref)) / 100; + sy1 = sy1 - (c->Cy1 * (t - t_ref)) / 100; + sy2 = sy2 - (c->Cy2 * (t - t_ref)) / 100; + } else { + /* + * YAS530 and YAS532 version AB use solely the t value as a + * multiplier. + * + * Cx * t + * x' = x - ------ + * 100 + */ + sx = sx - (c->Cx * t) / 100; + sy1 = sy1 - (c->Cy1 * t) / 100; + sy2 = sy2 - (c->Cy2 * t) / 100; + } /* * Break y1 and y2 into y and z, y1 and y2 are apparently encoding @@ -347,11 +378,37 @@ static int yas5xx_get_measure(struct yas5xx *yas5xx, s32 *to, s32 *xo, s32 *yo, sy = sy1 - sy2; sz = -sy1 - sy2; - /* - * FIXME: convert to Celsius? Just guessing this is given - * as 1/10:s of degrees so multiply by 100 to get millicentigrades. - */ - *to = t * 100; + /* Process temperature readout */ + switch (yas5xx->devid) { + case YAS530_DEVICE_ID: + /* + * Raw temperature value t is the number of counts starting + * at -62 °C. Reference value t_ref is the number of counts + * between -62 °C and 20 °C (82 °C range). + * + * Temperature in °C would be (82 / t_ref * t) - 62. + * + * Contrary to this, perform multiplication first and division + * second due to calculating with integers. + * + * To get a nicer result, calculate with 1/10:s degrees Celsius + * and finally multiply by 100 to return millidegrees Celsius. + */ + *to = ((820 * t / t_ref) - 620) * 100; + break; + case YAS532_DEVICE_ID: + /* + * Actually same procedure for YAS532 but the starting point is + * at -50 °C. Reference value t_ref is the number of counts + * between -50 °C and 20 °C (70 °C range). + */ + *to = ((700 * t / t_ref) - 500) * 100; + break; + default: + dev_err(yas5xx->dev, "unknown device type\n"); + return -EINVAL; + } + /* * Calibrate [x,y,z] with some formulas like this: * @@ -384,6 +441,7 @@ static int yas5xx_read_raw(struct iio_dev *indio_dev, int ret; switch (mask) { + case IIO_CHAN_INFO_PROCESSED: case IIO_CHAN_INFO_RAW: pm_runtime_get_sync(yas5xx->dev); ret = yas5xx_get_measure(yas5xx, &t, &x, &y, &z); @@ -410,11 +468,6 @@ static int yas5xx_read_raw(struct iio_dev *indio_dev, } return IIO_VAL_INT; case IIO_CHAN_INFO_SCALE: - if (chan->address == 0) { - /* Temperature is unscaled */ - *val = 1; - return IIO_VAL_INT; - } switch (yas5xx->devid) { case YAS530_DEVICE_ID: /* @@ -516,7 +569,7 @@ static const struct iio_chan_spec yas5xx_channels[] = { .address = 0, .scan_index = 0, .scan_type = { - .sign = 'u', + .sign = 's', .realbits = 32, .storagebits = 32, .endianness = IIO_CPU, |