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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 <jahau@rocketmail.com> Reviewed-by: Linus Walleij <linus.walleij@linaro.org> Link: https://lore.kernel.org/r/1a8bffdb7e807455620a73f2d61981e7f9aab8d5.1660337264.git.jahau@rocketmail.com Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
This commit is contained in:
Jakob Hauser
Jonathan Cameron
parent
913fd40966
commit
2d6676ecbe
@ -79,7 +79,6 @@
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#define YAS530_DATA_BITS 12
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#define YAS530_DATA_CENTER BIT(YAS530_DATA_BITS - 1)
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#define YAS530_DATA_OVERFLOW (BIT(YAS530_DATA_BITS) - 1)
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#define YAS530_20DEGREES 182 /* Counts starting at -62 °C */
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#define YAS532_DEVICE_ID 0x02 /* YAS532/YAS533 (MS-3R/F) */
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#define YAS532_VERSION_AB 0 /* YAS532/533 AB (MS-3R/F AB) */
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@ -91,7 +90,6 @@
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#define YAS532_DATA_BITS 13
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#define YAS532_DATA_CENTER BIT(YAS532_DATA_BITS - 1)
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#define YAS532_DATA_OVERFLOW (BIT(YAS532_DATA_BITS) - 1)
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#define YAS532_20DEGREES 390 /* Counts starting at -50 °C */
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/* Turn off device regulators etc after 5 seconds of inactivity */
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#define YAS5XX_AUTOSUSPEND_DELAY_MS 5000
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@ -131,6 +129,14 @@ struct yas5xx;
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* @volatile_reg: device-specific volatile registers
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* @volatile_reg_qty: quantity of device-specific volatile registers
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* @scaling_val2: scaling value for IIO_CHAN_INFO_SCALE
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* @t_ref: number of counts at reference temperature 20 °C
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* @min_temp_x10: starting point of temperature counting in 1/10:s degrees Celsius
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*
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* The "t_ref" value for YAS532/533 is known from the Android driver.
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* For YAS530 it was approximately measured.
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*
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* The temperatures "min_temp_x10" are derived from the temperature resolutions
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* given in the data sheets.
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*/
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struct yas5xx_chip_info {
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unsigned int devid;
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@ -139,6 +145,8 @@ struct yas5xx_chip_info {
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const int *volatile_reg;
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int volatile_reg_qty;
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u32 scaling_val2;
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u16 t_ref;
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s16 min_temp_x10;
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};
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/**
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@ -337,6 +345,22 @@ static s32 yas530_linearize(struct yas5xx *yas5xx, u16 val, int axis)
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(yas5xx->hard_offsets[axis] - c->r[axis]) * coef;
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}
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static s32 yas5xx_calc_temperature(struct yas5xx *yas5xx, u16 t)
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{
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const struct yas5xx_chip_info *ci = yas5xx->chip_info;
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s32 to;
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u16 t_ref;
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s16 min_temp_x10;
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int ref_temp_x10;
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t_ref = ci->t_ref;
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min_temp_x10 = ci->min_temp_x10;
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ref_temp_x10 = 200;
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to = (min_temp_x10 + ((ref_temp_x10 - min_temp_x10) * t / t_ref)) * 100;
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return to;
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}
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/**
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* yas530_get_measure() - Measure a sample of all axis and process
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* @yas5xx: The device state
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@ -352,7 +376,7 @@ static int yas530_get_measure(struct yas5xx *yas5xx, s32 *to, s32 *xo, s32 *yo,
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{
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const struct yas5xx_chip_info *ci = yas5xx->chip_info;
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struct yas5xx_calibration *c = &yas5xx->calibration;
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u16 t_ref, t, x, y1, y2;
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u16 t_ref, t_comp, t, x, y1, y2;
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/* These are signed x, signed y1 etc */
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s32 sx, sy1, sy2, sy, sz;
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int ret;
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@ -367,47 +391,30 @@ static int yas530_get_measure(struct yas5xx *yas5xx, s32 *to, s32 *xo, s32 *yo,
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sy1 = yas530_linearize(yas5xx, y1, 1);
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sy2 = yas530_linearize(yas5xx, y2, 2);
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/* Set the temperature reference value (unit: counts) */
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switch (ci->devid) {
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case YAS530_DEVICE_ID:
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t_ref = YAS530_20DEGREES;
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break;
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case YAS532_DEVICE_ID:
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t_ref = YAS532_20DEGREES;
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break;
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default:
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dev_err(yas5xx->dev, "unknown device type\n");
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return -EINVAL;
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}
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/* Temperature compensation for x, y1, y2 respectively */
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/*
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* Set the temperature for compensation (unit: counts):
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* YAS532/YAS533 version AC uses the temperature deviation as a
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* multiplier. YAS530 and YAS532 version AB use solely the t value.
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*/
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t_ref = ci->t_ref;
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if (ci->devid == YAS532_DEVICE_ID &&
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yas5xx->version == YAS532_VERSION_AC) {
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/*
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* YAS532 version AC uses the temperature deviation as a
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* multiplier.
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*
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* Cx * (t - t_ref)
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* x' = x - ----------------
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* 100
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*/
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sx = sx - (c->Cx * (t - t_ref)) / 100;
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sy1 = sy1 - (c->Cy1 * (t - t_ref)) / 100;
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sy2 = sy2 - (c->Cy2 * (t - t_ref)) / 100;
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t_comp = t - t_ref;
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} else {
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/*
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* YAS530 and YAS532 version AB use solely the t value as a
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* multiplier.
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*
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* Cx * t
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* x' = x - ------
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* 100
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*/
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sx = sx - (c->Cx * t) / 100;
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sy1 = sy1 - (c->Cy1 * t) / 100;
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sy2 = sy2 - (c->Cy2 * t) / 100;
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t_comp = t;
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}
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/*
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* Temperature compensation for x, y1, y2 respectively:
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*
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* Cx * t_comp
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* x' = x - -----------
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* 100
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*/
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sx = sx - (c->Cx * t_comp) / 100;
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sy1 = sy1 - (c->Cy1 * t_comp) / 100;
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sy2 = sy2 - (c->Cy2 * t_comp) / 100;
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/*
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* Break y1 and y2 into y and z, y1 and y2 are apparently encoding
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* y and z.
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@ -415,36 +422,8 @@ static int yas530_get_measure(struct yas5xx *yas5xx, s32 *to, s32 *xo, s32 *yo,
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sy = sy1 - sy2;
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sz = -sy1 - sy2;
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/* Process temperature readout */
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switch (ci->devid) {
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case YAS530_DEVICE_ID:
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/*
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* Raw temperature value t is the number of counts starting
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* at -62 °C. Reference value t_ref is the number of counts
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* between -62 °C and 20 °C (82 °C range).
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*
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* Temperature in °C would be (82 / t_ref * t) - 62.
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*
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* Contrary to this, perform multiplication first and division
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* second due to calculating with integers.
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*
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* To get a nicer result, calculate with 1/10:s degrees Celsius
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* and finally multiply by 100 to return millidegrees Celsius.
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*/
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*to = ((820 * t / t_ref) - 620) * 100;
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break;
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case YAS532_DEVICE_ID:
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/*
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* Actually same procedure for YAS532 but the starting point is
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* at -50 °C. Reference value t_ref is the number of counts
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* between -50 °C and 20 °C (70 °C range).
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*/
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*to = ((700 * t / t_ref) - 500) * 100;
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break;
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default:
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dev_err(yas5xx->dev, "unknown device type\n");
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return -EINVAL;
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}
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/* Calculate temperature readout */
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*to = yas5xx_calc_temperature(yas5xx, t);
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/*
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* Calibrate [x,y,z] with some formulas like this:
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@ -935,6 +914,8 @@ static const struct yas5xx_chip_info yas5xx_chip_info_tbl[] = {
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.volatile_reg = yas530_volatile_reg,
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.volatile_reg_qty = ARRAY_SIZE(yas530_volatile_reg),
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.scaling_val2 = 100000000, /* picotesla to Gauss */
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.t_ref = 182, /* counts */
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.min_temp_x10 = -620, /* 1/10:s degrees Celsius */
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},
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[yas532] = {
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.devid = YAS532_DEVICE_ID,
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@ -943,6 +924,8 @@ static const struct yas5xx_chip_info yas5xx_chip_info_tbl[] = {
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.volatile_reg = yas530_volatile_reg,
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.volatile_reg_qty = ARRAY_SIZE(yas530_volatile_reg),
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.scaling_val2 = 100000, /* nanotesla to Gauss */
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.t_ref = 390, /* counts */
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.min_temp_x10 = -500, /* 1/10:s degrees Celsius */
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},
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[yas533] = {
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.devid = YAS532_DEVICE_ID,
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@ -951,6 +934,8 @@ static const struct yas5xx_chip_info yas5xx_chip_info_tbl[] = {
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.volatile_reg = yas530_volatile_reg,
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.volatile_reg_qty = ARRAY_SIZE(yas530_volatile_reg),
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.scaling_val2 = 100000, /* nanotesla to Gauss */
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.t_ref = 390, /* counts */
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.min_temp_x10 = -500, /* 1/10:s degrees Celsius */
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},
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};
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