From 2d6676ecbe6a39fb1e002b89781e4158e77a784e Mon Sep 17 00:00:00 2001 From: Jakob Hauser Date: Sat, 13 Aug 2022 00:05:01 +0200 Subject: [PATCH] iio: magnetometer: yas530: Add temperature calculation to "chip_info" Add temperature calculation to the "chip_info" structure to ease the handling of different YAS variants. Signed-off-by: Jakob Hauser Reviewed-by: Linus Walleij Link: https://lore.kernel.org/r/1a8bffdb7e807455620a73f2d61981e7f9aab8d5.1660337264.git.jahau@rocketmail.com Signed-off-by: Jonathan Cameron --- drivers/iio/magnetometer/yamaha-yas530.c | 123 ++++++++++------------- 1 file changed, 54 insertions(+), 69 deletions(-) diff --git a/drivers/iio/magnetometer/yamaha-yas530.c b/drivers/iio/magnetometer/yamaha-yas530.c index af5c090098fb..a5d3f0bff024 100644 --- a/drivers/iio/magnetometer/yamaha-yas530.c +++ b/drivers/iio/magnetometer/yamaha-yas530.c @@ -79,7 +79,6 @@ #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) */ @@ -91,7 +90,6 @@ #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 /* Counts starting at -50 °C */ /* Turn off device regulators etc after 5 seconds of inactivity */ #define YAS5XX_AUTOSUSPEND_DELAY_MS 5000 @@ -131,6 +129,14 @@ struct yas5xx; * @volatile_reg: device-specific volatile registers * @volatile_reg_qty: quantity of device-specific volatile registers * @scaling_val2: scaling value for IIO_CHAN_INFO_SCALE + * @t_ref: number of counts at reference temperature 20 °C + * @min_temp_x10: starting point of temperature counting in 1/10:s degrees Celsius + * + * The "t_ref" value for YAS532/533 is known from the Android driver. + * For YAS530 it was approximately measured. + * + * The temperatures "min_temp_x10" are derived from the temperature resolutions + * given in the data sheets. */ struct yas5xx_chip_info { unsigned int devid; @@ -139,6 +145,8 @@ struct yas5xx_chip_info { const int *volatile_reg; int volatile_reg_qty; u32 scaling_val2; + u16 t_ref; + s16 min_temp_x10; }; /** @@ -337,6 +345,22 @@ static s32 yas530_linearize(struct yas5xx *yas5xx, u16 val, int axis) (yas5xx->hard_offsets[axis] - c->r[axis]) * coef; } +static s32 yas5xx_calc_temperature(struct yas5xx *yas5xx, u16 t) +{ + const struct yas5xx_chip_info *ci = yas5xx->chip_info; + s32 to; + u16 t_ref; + s16 min_temp_x10; + int ref_temp_x10; + + t_ref = ci->t_ref; + min_temp_x10 = ci->min_temp_x10; + ref_temp_x10 = 200; + + to = (min_temp_x10 + ((ref_temp_x10 - min_temp_x10) * t / t_ref)) * 100; + return to; +} + /** * yas530_get_measure() - Measure a sample of all axis and process * @yas5xx: The device state @@ -352,7 +376,7 @@ static int yas530_get_measure(struct yas5xx *yas5xx, s32 *to, s32 *xo, s32 *yo, { const struct yas5xx_chip_info *ci = yas5xx->chip_info; struct yas5xx_calibration *c = &yas5xx->calibration; - u16 t_ref, t, x, y1, y2; + u16 t_ref, t_comp, t, x, y1, y2; /* These are signed x, signed y1 etc */ s32 sx, sy1, sy2, sy, sz; int ret; @@ -367,47 +391,30 @@ static int yas530_get_measure(struct yas5xx *yas5xx, s32 *to, s32 *xo, s32 *yo, sy1 = yas530_linearize(yas5xx, y1, 1); sy2 = yas530_linearize(yas5xx, y2, 2); - /* Set the temperature reference value (unit: counts) */ - switch (ci->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 */ + /* + * Set the temperature for compensation (unit: counts): + * YAS532/YAS533 version AC uses the temperature deviation as a + * multiplier. YAS530 and YAS532 version AB use solely the t value. + */ + t_ref = ci->t_ref; if (ci->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; + t_comp = t - t_ref; } 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; + t_comp = t; } + /* + * Temperature compensation for x, y1, y2 respectively: + * + * Cx * t_comp + * x' = x - ----------- + * 100 + */ + sx = sx - (c->Cx * t_comp) / 100; + sy1 = sy1 - (c->Cy1 * t_comp) / 100; + sy2 = sy2 - (c->Cy2 * t_comp) / 100; + /* * Break y1 and y2 into y and z, y1 and y2 are apparently encoding * y and z. @@ -415,36 +422,8 @@ static int yas530_get_measure(struct yas5xx *yas5xx, s32 *to, s32 *xo, s32 *yo, sy = sy1 - sy2; sz = -sy1 - sy2; - /* Process temperature readout */ - switch (ci->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; - } + /* Calculate temperature readout */ + *to = yas5xx_calc_temperature(yas5xx, t); /* * Calibrate [x,y,z] with some formulas like this: @@ -935,6 +914,8 @@ static const struct yas5xx_chip_info yas5xx_chip_info_tbl[] = { .volatile_reg = yas530_volatile_reg, .volatile_reg_qty = ARRAY_SIZE(yas530_volatile_reg), .scaling_val2 = 100000000, /* picotesla to Gauss */ + .t_ref = 182, /* counts */ + .min_temp_x10 = -620, /* 1/10:s degrees Celsius */ }, [yas532] = { .devid = YAS532_DEVICE_ID, @@ -943,6 +924,8 @@ static const struct yas5xx_chip_info yas5xx_chip_info_tbl[] = { .volatile_reg = yas530_volatile_reg, .volatile_reg_qty = ARRAY_SIZE(yas530_volatile_reg), .scaling_val2 = 100000, /* nanotesla to Gauss */ + .t_ref = 390, /* counts */ + .min_temp_x10 = -500, /* 1/10:s degrees Celsius */ }, [yas533] = { .devid = YAS532_DEVICE_ID, @@ -951,6 +934,8 @@ static const struct yas5xx_chip_info yas5xx_chip_info_tbl[] = { .volatile_reg = yas530_volatile_reg, .volatile_reg_qty = ARRAY_SIZE(yas530_volatile_reg), .scaling_val2 = 100000, /* nanotesla to Gauss */ + .t_ref = 390, /* counts */ + .min_temp_x10 = -500, /* 1/10:s degrees Celsius */ }, };