[PATCH v3 11/15] iio: accel: adxl345: add g-range configuration

[Lothar Rubusch <l.rubusch@xxxxxxxxx>]

Introduce means to configure and work with the available g-ranges
keeping the precision of 13 digits.

This is in preparation for the activity/inactivity feature.

Signed-off-by: Lothar Rubusch <l.rubusch@xxxxxxxxx>
---
 drivers/iio/accel/adxl345_core.c | 91 ++++++++++++++++++++++++++++++--
 1 file changed, 88 insertions(+), 3 deletions(-)

diff --git a/drivers/iio/accel/adxl345_core.c b/drivers/iio/accel/adxl345_core.c
index fa169cac5c05..ab1ab09f348a 100644
--- a/drivers/iio/accel/adxl345_core.c
+++ b/drivers/iio/accel/adxl345_core.c
@@ -86,6 +86,13 @@ enum adxl345_odr {
 	ADXL345_ODR_3200HZ,
 };
 
+enum adxl345_range {
+	ADXL345_2G_RANGE = 0,
+	ADXL345_4G_RANGE,
+	ADXL345_8G_RANGE,
+	ADXL345_16G_RANGE,
+};
+
 /* Certain features recommend 12.5 Hz - 400 Hz ODR */
 static const int adxl345_odr_tbl[][2] = {
 	[ADXL345_ODR_0P10HZ]	= {    0,  97000 },
@@ -106,6 +113,33 @@ static const int adxl345_odr_tbl[][2] = {
 	[ADXL345_ODR_3200HZ]	= { 3200, 0 },
 };
 
+/*
+ * Full resolution frequency table:
+ * (g * 2 * 9.80665) / (2^(resolution) - 1)
+ *
+ * resolution := 13 (full)
+ * g := 2|4|8|16
+ *
+ *  2g at 13bit: 0.004789
+ *  4g at 13bit: 0.009578
+ *  8g at 13bit: 0.019156
+ * 16g at 16bit: 0.038312
+ */
+static const int adxl345_fullres_range_tbl[][2] = {
+	[ADXL345_2G_RANGE]  = { 0, 4789 },
+	[ADXL345_4G_RANGE]  = { 0, 9578 },
+	[ADXL345_8G_RANGE]  = { 0, 19156 },
+	[ADXL345_16G_RANGE] = { 0, 38312 },
+};
+
+/* scaling */
+static const int adxl345_range_factor_tbl[] = {
+	[ADXL345_2G_RANGE]  = 1,
+	[ADXL345_4G_RANGE]  = 2,
+	[ADXL345_8G_RANGE]  = 4,
+	[ADXL345_16G_RANGE] = 8,
+};
+
 struct adxl345_state {
 	const struct adxl345_chip_info *info;
 	struct regmap *regmap;
@@ -157,7 +191,8 @@ static struct iio_event_spec adxl345_events[] = {
 		BIT(IIO_CHAN_INFO_CALIBBIAS),				\
 	.info_mask_shared_by_type = BIT(IIO_CHAN_INFO_SCALE) |		\
 		BIT(IIO_CHAN_INFO_SAMP_FREQ),				\
-	.info_mask_shared_by_type_available = BIT(IIO_CHAN_INFO_SAMP_FREQ),		\
+	.info_mask_shared_by_type_available = BIT(IIO_CHAN_INFO_SCALE) | \
+		BIT(IIO_CHAN_INFO_SAMP_FREQ),		\
 	.scan_index = (index),				\
 	.scan_type = {					\
 		.sign = 's',				\
@@ -483,12 +518,48 @@ static int adxl345_set_odr(struct adxl345_state *st, enum adxl345_odr odr)
 	return 0;
 }
 
+static int adxl345_find_range(struct adxl345_state *st, int val, int val2,
+			      enum adxl345_range *range)
+{
+	int i;
+
+	for (i = 0; i < ARRAY_SIZE(adxl345_fullres_range_tbl); i++)
+		if (val == adxl345_fullres_range_tbl[i][0] &&
+		    val2 == adxl345_fullres_range_tbl[i][1])
+			break;
+
+	if (i == ARRAY_SIZE(adxl345_fullres_range_tbl))
+		return -EINVAL;
+
+	*range = i;
+
+	return 0;
+}
+
+static int adxl345_set_range(struct adxl345_state *st, enum adxl345_range range)
+{
+	int ret;
+
+	ret = regmap_update_bits(st->regmap, ADXL345_REG_DATA_FORMAT,
+				 ADXL345_DATA_FORMAT_RANGE,
+				 FIELD_PREP(ADXL345_DATA_FORMAT_RANGE, range));
+	if (ret)
+		return ret;
+
+	return 0;
+}
+
 static int adxl345_read_avail(struct iio_dev *indio_dev,
 			      struct iio_chan_spec const *chan,
 			      const int **vals, int *type,
 			      int *length, long mask)
 {
 	switch (mask) {
+	case IIO_CHAN_INFO_SCALE:
+		*vals = (int *)adxl345_fullres_range_tbl;
+		*type = IIO_VAL_INT_PLUS_MICRO;
+		*length = ARRAY_SIZE(adxl345_fullres_range_tbl) * 2;
+		return IIO_AVAIL_LIST;
 	case IIO_CHAN_INFO_SAMP_FREQ:
 		*vals = (int *)adxl345_odr_tbl;
 		*type = IIO_VAL_INT_PLUS_MICRO;
@@ -507,6 +578,7 @@ static int adxl345_read_raw(struct iio_dev *indio_dev,
 	__le16 accel;
 	unsigned int regval;
 	enum adxl345_odr odr;
+	enum adxl345_range range;
 	int ret;
 
 	switch (mask) {
@@ -525,8 +597,12 @@ static int adxl345_read_raw(struct iio_dev *indio_dev,
 		*val = sign_extend32(le16_to_cpu(accel), 12);
 		return IIO_VAL_INT;
 	case IIO_CHAN_INFO_SCALE:
-		*val = 0;
-		*val2 = st->info->uscale;
+		ret = regmap_read(st->regmap, ADXL345_REG_DATA_FORMAT, &regval);
+		if (ret)
+			return ret;
+		range = FIELD_GET(ADXL345_DATA_FORMAT_RANGE, regval);
+		*val = adxl345_fullres_range_tbl[range][0];
+		*val2 = adxl345_fullres_range_tbl[range][1];
 		return IIO_VAL_INT_PLUS_MICRO;
 	case IIO_CHAN_INFO_CALIBBIAS:
 		ret = regmap_read(st->regmap,
@@ -558,6 +634,7 @@ static int adxl345_write_raw(struct iio_dev *indio_dev,
 			     int val, int val2, long mask)
 {
 	struct adxl345_state *st = iio_priv(indio_dev);
+	enum adxl345_range range;
 	enum adxl345_odr odr;
 	int ret;
 
@@ -581,6 +658,12 @@ static int adxl345_write_raw(struct iio_dev *indio_dev,
 			return ret;
 		ret = adxl345_set_odr(st, odr);
 		break;
+	case IIO_CHAN_INFO_SCALE:
+		ret = adxl345_find_range(st, val, val2,	&range);
+		if (ret)
+			return ret;
+		ret = adxl345_set_range(st, range);
+		break;
 	default:
 		return -EINVAL;
 	}
@@ -840,6 +923,8 @@ static int adxl345_write_raw_get_fmt(struct iio_dev *indio_dev,
 	switch (mask) {
 	case IIO_CHAN_INFO_CALIBBIAS:
 		return IIO_VAL_INT;
+	case IIO_CHAN_INFO_SCALE:
+		return IIO_VAL_INT_PLUS_MICRO;
 	case IIO_CHAN_INFO_SAMP_FREQ:
 		return IIO_VAL_INT_PLUS_MICRO;
 	default:
-- 
2.39.5