[PATCH 2/2] iio: accel: adxl380: Add support for 1 kHz sampling frequency

[Francesco Lavra <flavra@baylibre.com>]

In sensor variants (such as ADXL380 and ADXL382) that support low-power
mode, the SAR signal path allows sampling acceleration data at lower rates;
more specifically, when the sensor operates in VLP mode, the sampling
frequency is 1 kHz.
To add support for the 1kHz sampling frequency value, modify the operating
mode selection logic to take into account the sampling frequency, and
configure the decimation filters only when applicable (i.e. when using a
sampling frequency that relies on the DSM signal path).

Signed-off-by: Francesco Lavra <flavra@baylibre.com>
---
 drivers/iio/accel/adxl380.c | 49 +++++++++++++++++++++++--------------
 drivers/iio/accel/adxl380.h | 10 +++++++-
 2 files changed, 40 insertions(+), 19 deletions(-)

diff --git a/drivers/iio/accel/adxl380.c b/drivers/iio/accel/adxl380.c
index bbf1f88ca781..a6919dfce2e9 100644
--- a/drivers/iio/accel/adxl380.c
+++ b/drivers/iio/accel/adxl380.c
@@ -245,12 +245,14 @@ static int adxl380_set_measure_en(struct adxl380_state *st, bool en)
 
 		/*
 		 * Activity/Inactivity detection available only in VLP/ULP
-		 * mode and for devices that support low power modes. Otherwise
-		 * go straight to measure mode (same bits as ADXL380_OP_MODE_HP).
+		 * mode and for devices that support low power modes.
 		 */
 		if (st->chip_info->has_low_power &&
 		    (FIELD_GET(ADXL380_ACT_EN_MSK, act_inact_ctl) ||
 		     FIELD_GET(ADXL380_INACT_EN_MSK, act_inact_ctl)))
+			st->odr = ADXL380_ODR_VLP;
+
+		if (st->odr == ADXL380_ODR_VLP)
 			op_mode = ADXL380_OP_MODE_VLP;
 		else
 			op_mode = ADXL380_OP_MODE_HP;
@@ -478,17 +480,22 @@ static int adxl380_set_odr(struct adxl380_state *st, u8 odr)
 	if (ret)
 		return ret;
 
-	ret = regmap_update_bits(st->regmap, ADXL380_TRIG_CFG_REG,
-				 ADXL380_TRIG_CFG_DEC_2X_MSK,
-				 FIELD_PREP(ADXL380_TRIG_CFG_DEC_2X_MSK, odr & 1));
-	if (ret)
-		return ret;
+	if (odr >= ADXL380_ODR_DSM) {
+		u8 mul = odr - ADXL380_ODR_DSM;
+		u8 field;
 
-	ret = regmap_update_bits(st->regmap, ADXL380_TRIG_CFG_REG,
-				 ADXL380_TRIG_CFG_SINC_RATE_MSK,
-				 FIELD_PREP(ADXL380_TRIG_CFG_SINC_RATE_MSK, odr >> 1));
-	if (ret)
-		return ret;
+		field = FIELD_PREP(ADXL380_TRIG_CFG_DEC_2X_MSK, mul & 1);
+		ret = regmap_update_bits(st->regmap, ADXL380_TRIG_CFG_REG,
+					 ADXL380_TRIG_CFG_DEC_2X_MSK, field);
+		if (ret)
+			return ret;
+
+		field = FIELD_PREP(ADXL380_TRIG_CFG_SINC_RATE_MSK, mul >> 1);
+		ret = regmap_update_bits(st->regmap, ADXL380_TRIG_CFG_REG,
+					 ADXL380_TRIG_CFG_SINC_RATE_MSK, field);
+		if (ret)
+			return ret;
+	}
 
 	st->odr = odr;
 	ret = adxl380_set_measure_en(st, true);
@@ -1219,9 +1226,14 @@ static int adxl380_read_avail(struct iio_dev *indio_dev,
 		*length = ARRAY_SIZE(st->chip_info->scale_tbl) * 2;
 		return IIO_AVAIL_LIST;
 	case IIO_CHAN_INFO_SAMP_FREQ:
-		*vals = (const int *)st->chip_info->samp_freq_tbl;
+		if (st->chip_info->has_low_power) {
+			*vals = st->chip_info->samp_freq_tbl;
+			*length = ADXL380_ODR_MAX;
+		} else {
+			*vals = st->chip_info->samp_freq_tbl + ADXL380_ODR_DSM;
+			*length = ADXL380_ODR_MAX - ADXL380_ODR_DSM;
+		}
 		*type = IIO_VAL_INT;
-		*length = ARRAY_SIZE(st->chip_info->samp_freq_tbl);
 		return IIO_AVAIL_LIST;
 	case IIO_CHAN_INFO_LOW_PASS_FILTER_3DB_FREQUENCY:
 		*vals = (const int *)st->lpf_tbl;
@@ -1611,7 +1623,7 @@ const struct adxl380_chip_info adxl318_chip_info = {
 		[ADXL380_OP_MODE_8G_RANGE] = { 0, 2615434 },
 		[ADXL380_OP_MODE_16G_RANGE] = { 0, 5229886 },
 	},
-	.samp_freq_tbl = { 8000, 16000, 32000 },
+	.samp_freq_tbl = { 0, 8000, 16000, 32000 },
 	/*
 	 * The datasheet defines an intercept of 550 LSB at 25 degC
 	 * and a sensitivity of 10.2 LSB/C.
@@ -1629,7 +1641,7 @@ const struct adxl380_chip_info adxl319_chip_info = {
 		[ADXL382_OP_MODE_30G_RANGE] = { 0, 9806650 },
 		[ADXL382_OP_MODE_60G_RANGE] = { 0, 19613300 },
 	},
-	.samp_freq_tbl = { 16000, 32000, 64000 },
+	.samp_freq_tbl = { 0, 16000, 32000, 64000 },
 	/*
 	 * The datasheet defines an intercept of 550 LSB at 25 degC
 	 * and a sensitivity of 10.2 LSB/C.
@@ -1647,7 +1659,7 @@ const struct adxl380_chip_info adxl380_chip_info = {
 		[ADXL380_OP_MODE_8G_RANGE] = { 0, 2615434 },
 		[ADXL380_OP_MODE_16G_RANGE] = { 0, 5229886 },
 	},
-	.samp_freq_tbl = { 8000, 16000, 32000 },
+	.samp_freq_tbl = { 1000, 8000, 16000, 32000 },
 	/*
 	 * The datasheet defines an intercept of 470 LSB at 25 degC
 	 * and a sensitivity of 10.2 LSB/C.
@@ -1667,7 +1679,7 @@ const struct adxl380_chip_info adxl382_chip_info = {
 		[ADXL382_OP_MODE_30G_RANGE] = { 0, 9806650 },
 		[ADXL382_OP_MODE_60G_RANGE] = { 0, 19613300 },
 	},
-	.samp_freq_tbl = { 16000, 32000, 64000 },
+	.samp_freq_tbl = { 1000, 16000, 32000, 64000 },
 	/*
 	 * The datasheet defines an intercept of 570 LSB at 25 degC
 	 * and a sensitivity of 10.2 LSB/C.
@@ -1906,6 +1918,7 @@ int adxl380_probe(struct device *dev, struct regmap *regmap,
 	st->dev = dev;
 	st->regmap = regmap;
 	st->chip_info = chip_info;
+	st->odr = ADXL380_ODR_DSM;
 
 	mutex_init(&st->lock);
 
diff --git a/drivers/iio/accel/adxl380.h b/drivers/iio/accel/adxl380.h
index e67c5aab8efc..d2c260c8b2fa 100644
--- a/drivers/iio/accel/adxl380.h
+++ b/drivers/iio/accel/adxl380.h
@@ -8,10 +8,18 @@
 #ifndef _ADXL380_H_
 #define _ADXL380_H_
 
+enum adxl380_odr {
+	ADXL380_ODR_VLP,
+	ADXL380_ODR_DSM,
+	ADXL380_ODR_DSM_2X,
+	ADXL380_ODR_DSM_4X,
+	ADXL380_ODR_MAX
+};
+
 struct adxl380_chip_info {
 	const char *name;
 	const int scale_tbl[3][2];
-	const int samp_freq_tbl[3];
+	const int samp_freq_tbl[ADXL380_ODR_MAX];
 	const struct iio_info *info;
 	const int temp_offset;
 	const u16 chip_id;
-- 
2.39.5