[PATCH v4 2/2] iio: imu: inv_icm42600: add support of accel low-power mode

[inv.git-commit@tdk.com]

From: Jean-Baptiste Maneyrol <jean-baptiste.maneyrol@tdk.com>

Add ODRs accessible only in low-power mode. Switch automatically to
low-power or low-noise depending on the ODR set.

Add channel attributes "power_mode" and "power_mode_available" for
setting the power mode to use (low-noise or low-power) for ODRs
supporting both mode. Reading "power_mode" when the sensor is on
will return the actual mode and not the requested one. It will be
different when using ODRs not supported by the requested mode.

Use low-power mode by default.

Signed-off-by: Jean-Baptiste Maneyrol <jean-baptiste.maneyrol@tdk.com>
---
 drivers/iio/imu/inv_icm42600/inv_icm42600.h   |   4 +
 .../iio/imu/inv_icm42600/inv_icm42600_accel.c | 124 +++++++++++++++++-
 .../iio/imu/inv_icm42600/inv_icm42600_core.c  |  27 ++++
 3 files changed, 151 insertions(+), 4 deletions(-)

diff --git a/drivers/iio/imu/inv_icm42600/inv_icm42600.h b/drivers/iio/imu/inv_icm42600/inv_icm42600.h
index c4ac91f6bafe..3a07e43e4cf1 100644
--- a/drivers/iio/imu/inv_icm42600/inv_icm42600.h
+++ b/drivers/iio/imu/inv_icm42600/inv_icm42600.h
@@ -177,11 +177,15 @@ struct inv_icm42600_state {
  * struct inv_icm42600_sensor_state - sensor state variables
  * @scales:		table of scales.
  * @scales_len:		length (nb of items) of the scales table.
+ * @power_mode:		sensor requested power mode (for common frequencies)
+ * @filter:		sensor filter.
  * @ts:			timestamp module states.
  */
 struct inv_icm42600_sensor_state {
 	const int *scales;
 	size_t scales_len;
+	enum inv_icm42600_sensor_mode power_mode;
+	enum inv_icm42600_filter filter;
 	struct inv_sensors_timestamp ts;
 };
 
diff --git a/drivers/iio/imu/inv_icm42600/inv_icm42600_accel.c b/drivers/iio/imu/inv_icm42600/inv_icm42600_accel.c
index 83d8504ebfff..3927829dd344 100644
--- a/drivers/iio/imu/inv_icm42600/inv_icm42600_accel.c
+++ b/drivers/iio/imu/inv_icm42600/inv_icm42600_accel.c
@@ -55,8 +55,108 @@ enum inv_icm42600_accel_scan {
 	INV_ICM42600_ACCEL_SCAN_TIMESTAMP,
 };
 
+static const char * const inv_icm42600_accel_power_mode_items[] = {
+	"low-noise",
+	"low-power",
+};
+static const int inv_icm42600_accel_power_mode_values[] = {
+	INV_ICM42600_SENSOR_MODE_LOW_NOISE,
+	INV_ICM42600_SENSOR_MODE_LOW_POWER,
+};
+static const int inv_icm42600_accel_filter_values[] = {
+	INV_ICM42600_FILTER_BW_ODR_DIV_2,
+	INV_ICM42600_FILTER_AVG_16X,
+};
+
+static int inv_icm42600_accel_power_mode_set(struct iio_dev *indio_dev,
+					     const struct iio_chan_spec *chan,
+					     unsigned int idx)
+{
+	struct inv_icm42600_state *st = iio_device_get_drvdata(indio_dev);
+	struct inv_icm42600_sensor_state *accel_st = iio_priv(indio_dev);
+	int power_mode, filter;
+
+	if (chan->type != IIO_ACCEL)
+		return -EINVAL;
+
+	if (idx >= ARRAY_SIZE(inv_icm42600_accel_power_mode_values))
+		return -EINVAL;
+
+	if (iio_buffer_enabled(indio_dev))
+		return -EBUSY;
+
+	power_mode = inv_icm42600_accel_power_mode_values[idx];
+	filter = inv_icm42600_accel_filter_values[idx];
+
+	guard(mutex)(&st->lock);
+
+	/* prevent change if power mode is not supported by the ODR */
+	switch (power_mode) {
+	case INV_ICM42600_SENSOR_MODE_LOW_NOISE:
+		if (st->conf.accel.odr >= INV_ICM42600_ODR_6_25HZ_LP &&
+		    st->conf.accel.odr <= INV_ICM42600_ODR_1_5625HZ_LP)
+			return -EPERM;
+		break;
+	case INV_ICM42600_SENSOR_MODE_LOW_POWER:
+	default:
+		if (st->conf.accel.odr <= INV_ICM42600_ODR_1KHZ_LN)
+			return -EPERM;
+		break;
+	}
+
+	accel_st->power_mode = power_mode;
+	accel_st->filter = filter;
+
+	return 0;
+}
+
+static int inv_icm42600_accel_power_mode_get(struct iio_dev *indio_dev,
+					     const struct iio_chan_spec *chan)
+{
+	struct inv_icm42600_state *st = iio_device_get_drvdata(indio_dev);
+	struct inv_icm42600_sensor_state *accel_st = iio_priv(indio_dev);
+	unsigned int idx;
+	int power_mode;
+
+	if (chan->type != IIO_ACCEL)
+		return -EINVAL;
+
+	guard(mutex)(&st->lock);
+
+	/* if sensor is on, returns actual power mode and not configured one */
+	switch (st->conf.accel.mode) {
+	case INV_ICM42600_SENSOR_MODE_LOW_POWER:
+	case INV_ICM42600_SENSOR_MODE_LOW_NOISE:
+		power_mode = st->conf.accel.mode;
+		break;
+	default:
+		power_mode = accel_st->power_mode;
+		break;
+	}
+
+	for (idx = 0; idx < ARRAY_SIZE(inv_icm42600_accel_power_mode_values); ++idx) {
+		if (power_mode == inv_icm42600_accel_power_mode_values[idx])
+			break;
+	}
+	if (idx >= ARRAY_SIZE(inv_icm42600_accel_power_mode_values))
+		return -EINVAL;
+
+	return idx;
+}
+
+static const struct iio_enum inv_icm42600_accel_power_mode_enum = {
+	.items = inv_icm42600_accel_power_mode_items,
+	.num_items = ARRAY_SIZE(inv_icm42600_accel_power_mode_items),
+	.set = inv_icm42600_accel_power_mode_set,
+	.get = inv_icm42600_accel_power_mode_get,
+};
+
 static const struct iio_chan_spec_ext_info inv_icm42600_accel_ext_infos[] = {
 	IIO_MOUNT_MATRIX(IIO_SHARED_BY_ALL, inv_icm42600_get_mount_matrix),
+	IIO_ENUM_AVAILABLE("power_mode", IIO_SHARED_BY_TYPE,
+			   &inv_icm42600_accel_power_mode_enum),
+	IIO_ENUM("power_mode", IIO_SHARED_BY_TYPE,
+		 &inv_icm42600_accel_power_mode_enum),
 	{},
 };
 
@@ -120,7 +220,8 @@ static int inv_icm42600_accel_update_scan_mode(struct iio_dev *indio_dev,
 
 	if (*scan_mask & INV_ICM42600_SCAN_MASK_ACCEL_3AXIS) {
 		/* enable accel sensor */
-		conf.mode = INV_ICM42600_SENSOR_MODE_LOW_NOISE;
+		conf.mode = accel_st->power_mode;
+		conf.filter = accel_st->filter;
 		ret = inv_icm42600_set_accel_conf(st, &conf, &sleep_accel);
 		if (ret)
 			goto out_unlock;
@@ -144,10 +245,12 @@ static int inv_icm42600_accel_update_scan_mode(struct iio_dev *indio_dev,
 	return ret;
 }
 
-static int inv_icm42600_accel_read_sensor(struct inv_icm42600_state *st,
+static int inv_icm42600_accel_read_sensor(struct iio_dev *indio_dev,
 					  struct iio_chan_spec const *chan,
 					  int16_t *val)
 {
+	struct inv_icm42600_state *st = iio_device_get_drvdata(indio_dev);
+	struct inv_icm42600_sensor_state *accel_st = iio_priv(indio_dev);
 	struct device *dev = regmap_get_device(st->map);
 	struct inv_icm42600_sensor_conf conf = INV_ICM42600_SENSOR_CONF_INIT;
 	unsigned int reg;
@@ -175,7 +278,8 @@ static int inv_icm42600_accel_read_sensor(struct inv_icm42600_state *st,
 	mutex_lock(&st->lock);
 
 	/* enable accel sensor */
-	conf.mode = INV_ICM42600_SENSOR_MODE_LOW_NOISE;
+	conf.mode = accel_st->power_mode;
+	conf.filter = accel_st->filter;
 	ret = inv_icm42600_set_accel_conf(st, &conf, NULL);
 	if (ret)
 		goto exit;
@@ -277,6 +381,12 @@ static int inv_icm42600_accel_write_scale(struct iio_dev *indio_dev,
 
 /* IIO format int + micro */
 static const int inv_icm42600_accel_odr[] = {
+	/* 1.5625Hz */
+	1, 562500,
+	/* 3.125Hz */
+	3, 125000,
+	/* 6.25Hz */
+	6, 250000,
 	/* 12.5Hz */
 	12, 500000,
 	/* 25Hz */
@@ -296,6 +406,9 @@ static const int inv_icm42600_accel_odr[] = {
 };
 
 static const int inv_icm42600_accel_odr_conv[] = {
+	INV_ICM42600_ODR_1_5625HZ_LP,
+	INV_ICM42600_ODR_3_125HZ_LP,
+	INV_ICM42600_ODR_6_25HZ_LP,
 	INV_ICM42600_ODR_12_5HZ,
 	INV_ICM42600_ODR_25HZ,
 	INV_ICM42600_ODR_50HZ,
@@ -581,7 +694,7 @@ static int inv_icm42600_accel_read_raw(struct iio_dev *indio_dev,
 		ret = iio_device_claim_direct_mode(indio_dev);
 		if (ret)
 			return ret;
-		ret = inv_icm42600_accel_read_sensor(st, chan, &data);
+		ret = inv_icm42600_accel_read_sensor(indio_dev, chan, &data);
 		iio_device_release_direct_mode(indio_dev);
 		if (ret)
 			return ret;
@@ -754,6 +867,9 @@ struct iio_dev *inv_icm42600_accel_init(struct inv_icm42600_state *st)
 		accel_st->scales_len = ARRAY_SIZE(inv_icm42600_accel_scale);
 		break;
 	}
+	/* low-power by default at init */
+	accel_st->power_mode = INV_ICM42600_SENSOR_MODE_LOW_POWER;
+	accel_st->filter = INV_ICM42600_FILTER_AVG_16X;
 
 	/*
 	 * clock period is 32kHz (31250ns)
diff --git a/drivers/iio/imu/inv_icm42600/inv_icm42600_core.c b/drivers/iio/imu/inv_icm42600/inv_icm42600_core.c
index 96116a68ab29..edf19a8a2f39 100644
--- a/drivers/iio/imu/inv_icm42600/inv_icm42600_core.c
+++ b/drivers/iio/imu/inv_icm42600/inv_icm42600_core.c
@@ -248,6 +248,23 @@ int inv_icm42600_set_accel_conf(struct inv_icm42600_state *st,
 	if (conf->filter < 0)
 		conf->filter = oldconf->filter;
 
+	/* force power mode against ODR when sensor is on */
+	switch (conf->mode) {
+	case INV_ICM42600_SENSOR_MODE_LOW_POWER:
+	case INV_ICM42600_SENSOR_MODE_LOW_NOISE:
+		if (conf->odr <= INV_ICM42600_ODR_1KHZ_LN) {
+			conf->mode = INV_ICM42600_SENSOR_MODE_LOW_NOISE;
+			conf->filter = INV_ICM42600_FILTER_BW_ODR_DIV_2;
+		} else if (conf->odr >= INV_ICM42600_ODR_6_25HZ_LP &&
+			   conf->odr <= INV_ICM42600_ODR_1_5625HZ_LP) {
+			conf->mode = INV_ICM42600_SENSOR_MODE_LOW_POWER;
+			conf->filter = INV_ICM42600_FILTER_AVG_16X;
+		}
+		break;
+	default:
+		break;
+	}
+
 	/* set ACCEL_CONFIG0 register (accel fullscale & odr) */
 	if (conf->fs != oldconf->fs || conf->odr != oldconf->odr) {
 		val = INV_ICM42600_ACCEL_CONFIG0_FS(conf->fs) |
@@ -441,6 +458,16 @@ static int inv_icm42600_setup(struct inv_icm42600_state *st,
 	if (ret)
 		return ret;
 
+	/*
+	 * Use RC clock for accel low-power to fix glitches when switching
+	 * gyro on/off while accel low-power is on.
+	 */
+	ret = regmap_update_bits(st->map, INV_ICM42600_REG_INTF_CONFIG1,
+				 INV_ICM42600_INTF_CONFIG1_ACCEL_LP_CLK_RC,
+				 INV_ICM42600_INTF_CONFIG1_ACCEL_LP_CLK_RC);
+	if (ret)
+		return ret;
+
 	return inv_icm42600_set_conf(st, hw->conf);
 }
 
-- 
2.34.1