[PATCH 08/13] iio: imu: inv_mpu6050: rewrite power and engine management

[Jean-Baptiste Maneyrol <jmaneyrol@invensense.com>]

Rewrite clock management to use automatic clock switching
present since MPU6500.
Sensors engine management can now turn on or off a batch of
sensors which simplifies usage a lot.
Temperature sensor is now turned on/off depending on usage.

Signed-off-by: Jean-Baptiste Maneyrol <jmaneyrol@invensense.com>
---
 drivers/iio/imu/inv_mpu6050/inv_mpu_core.c    | 264 +++++++++++++-----
 drivers/iio/imu/inv_mpu6050/inv_mpu_iio.h     |  24 +-
 drivers/iio/imu/inv_mpu6050/inv_mpu_magn.c    |  12 +-
 drivers/iio/imu/inv_mpu6050/inv_mpu_magn.h    |   2 +-
 drivers/iio/imu/inv_mpu6050/inv_mpu_trigger.c |  91 +++---
 5 files changed, 262 insertions(+), 131 deletions(-)

diff --git a/drivers/iio/imu/inv_mpu6050/inv_mpu_core.c b/drivers/iio/imu/inv_mpu6050/inv_mpu_core.c
index 63cdde20df7e..a51efc4c941b 100644
--- a/drivers/iio/imu/inv_mpu6050/inv_mpu_core.c
+++ b/drivers/iio/imu/inv_mpu6050/inv_mpu_core.c
@@ -99,9 +99,31 @@ static const struct inv_mpu6050_reg_map reg_set_6050 = {
 };
 
 static const struct inv_mpu6050_chip_config chip_config_6050 = {
+	.clk = INV_CLK_INTERNAL,
 	.fsr = INV_MPU6050_FSR_2000DPS,
 	.lpf = INV_MPU6050_FILTER_20HZ,
 	.divider = INV_MPU6050_FIFO_RATE_TO_DIVIDER(50),
+	.gyro_en = true,
+	.accl_en = true,
+	.temp_en = true,
+	.magn_en = false,
+	.gyro_fifo_enable = false,
+	.accl_fifo_enable = false,
+	.temp_fifo_enable = false,
+	.magn_fifo_enable = false,
+	.accl_fs = INV_MPU6050_FS_02G,
+	.user_ctrl = 0,
+};
+
+static const struct inv_mpu6050_chip_config chip_config_6500 = {
+	.clk = INV_CLK_PLL,
+	.fsr = INV_MPU6050_FSR_2000DPS,
+	.lpf = INV_MPU6050_FILTER_20HZ,
+	.divider = INV_MPU6050_FIFO_RATE_TO_DIVIDER(50),
+	.gyro_en = true,
+	.accl_en = true,
+	.temp_en = true,
+	.magn_en = false,
 	.gyro_fifo_enable = false,
 	.accl_fifo_enable = false,
 	.temp_fifo_enable = false,
@@ -124,7 +146,7 @@ static const struct inv_mpu6050_hw hw_info[] = {
 		.whoami = INV_MPU6500_WHOAMI_VALUE,
 		.name = "MPU6500",
 		.reg = &reg_set_6500,
-		.config = &chip_config_6050,
+		.config = &chip_config_6500,
 		.fifo_size = 512,
 		.temp = {INV_MPU6500_TEMP_OFFSET, INV_MPU6500_TEMP_SCALE},
 	},
@@ -132,7 +154,7 @@ static const struct inv_mpu6050_hw hw_info[] = {
 		.whoami = INV_MPU6515_WHOAMI_VALUE,
 		.name = "MPU6515",
 		.reg = &reg_set_6500,
-		.config = &chip_config_6050,
+		.config = &chip_config_6500,
 		.fifo_size = 512,
 		.temp = {INV_MPU6500_TEMP_OFFSET, INV_MPU6500_TEMP_SCALE},
 	},
@@ -156,7 +178,7 @@ static const struct inv_mpu6050_hw hw_info[] = {
 		.whoami = INV_MPU9250_WHOAMI_VALUE,
 		.name = "MPU9250",
 		.reg = &reg_set_6500,
-		.config = &chip_config_6050,
+		.config = &chip_config_6500,
 		.fifo_size = 512,
 		.temp = {INV_MPU6500_TEMP_OFFSET, INV_MPU6500_TEMP_SCALE},
 	},
@@ -164,7 +186,7 @@ static const struct inv_mpu6050_hw hw_info[] = {
 		.whoami = INV_MPU9255_WHOAMI_VALUE,
 		.name = "MPU9255",
 		.reg = &reg_set_6500,
-		.config = &chip_config_6050,
+		.config = &chip_config_6500,
 		.fifo_size = 512,
 		.temp = {INV_MPU6500_TEMP_OFFSET, INV_MPU6500_TEMP_SCALE},
 	},
@@ -172,7 +194,7 @@ static const struct inv_mpu6050_hw hw_info[] = {
 		.whoami = INV_ICM20608_WHOAMI_VALUE,
 		.name = "ICM20608",
 		.reg = &reg_set_6500,
-		.config = &chip_config_6050,
+		.config = &chip_config_6500,
 		.fifo_size = 512,
 		.temp = {INV_ICM20608_TEMP_OFFSET, INV_ICM20608_TEMP_SCALE},
 	},
@@ -180,7 +202,7 @@ static const struct inv_mpu6050_hw hw_info[] = {
 		.whoami = INV_ICM20609_WHOAMI_VALUE,
 		.name = "ICM20609",
 		.reg = &reg_set_6500,
-		.config = &chip_config_6050,
+		.config = &chip_config_6500,
 		.fifo_size = 4 * 1024,
 		.temp = {INV_ICM20608_TEMP_OFFSET, INV_ICM20608_TEMP_SCALE},
 	},
@@ -188,7 +210,7 @@ static const struct inv_mpu6050_hw hw_info[] = {
 		.whoami = INV_ICM20689_WHOAMI_VALUE,
 		.name = "ICM20689",
 		.reg = &reg_set_6500,
-		.config = &chip_config_6050,
+		.config = &chip_config_6500,
 		.fifo_size = 4 * 1024,
 		.temp = {INV_ICM20608_TEMP_OFFSET, INV_ICM20608_TEMP_SCALE},
 	},
@@ -196,15 +218,15 @@ static const struct inv_mpu6050_hw hw_info[] = {
 		.whoami = INV_ICM20602_WHOAMI_VALUE,
 		.name = "ICM20602",
 		.reg = &reg_set_icm20602,
-		.config = &chip_config_6050,
+		.config = &chip_config_6500,
 		.fifo_size = 1008,
 		.temp = {INV_ICM20608_TEMP_OFFSET, INV_ICM20608_TEMP_SCALE},
 	},
 	{
 		.whoami = INV_ICM20690_WHOAMI_VALUE,
 		.name = "ICM20690",
-		.reg = &reg_set_icm20602,
-		.config = &chip_config_6050,
+		.reg = &reg_set_6500,
+		.config = &chip_config_6500,
 		.fifo_size = 1024,
 		.temp = {INV_ICM20608_TEMP_OFFSET, INV_ICM20608_TEMP_SCALE},
 	},
@@ -212,61 +234,162 @@ static const struct inv_mpu6050_hw hw_info[] = {
 		.whoami = INV_IAM20680_WHOAMI_VALUE,
 		.name = "IAM20680",
 		.reg = &reg_set_6500,
-		.config = &chip_config_6050,
+		.config = &chip_config_6500,
 		.fifo_size = 512,
 		.temp = {INV_ICM20608_TEMP_OFFSET, INV_ICM20608_TEMP_SCALE},
 	},
 };
 
-int inv_mpu6050_switch_engine(struct inv_mpu6050_state *st, bool en, u32 mask)
+static int inv_mpu6050_pwr_mgmt_1_write(struct inv_mpu6050_state *st, bool sleep,
+					int clock, int temp_dis)
 {
-	unsigned int d, mgmt_1;
-	int result;
-	/*
-	 * switch clock needs to be careful. Only when gyro is on, can
-	 * clock source be switched to gyro. Otherwise, it must be set to
-	 * internal clock
-	 */
-	if (mask == INV_MPU6050_BIT_PWR_GYRO_STBY) {
-		result = regmap_read(st->map, st->reg->pwr_mgmt_1, &mgmt_1);
-		if (result)
-			return result;
+	u8 val;
+
+	if (clock < 0)
+		clock = st->chip_config.clk;
+	if (temp_dis < 0)
+		temp_dis = !st->chip_config.temp_en;
+
+	val = clock & INV_MPU6050_BIT_CLK_MASK;
+	if (temp_dis)
+		val |= INV_MPU6050_BIT_TEMP_DIS;
+	if (sleep)
+		val |= INV_MPU6050_BIT_SLEEP;
+
+	dev_dbg(regmap_get_device(st->map), "pwr_mgmt_1: 0x%x\n", val);
+	return regmap_write(st->map, st->reg->pwr_mgmt_1, val);
+}
+
+static int inv_mpu6050_clock_switch(struct inv_mpu6050_state *st,
+				    unsigned int clock)
+{
+	int ret;
+
+	switch (st->chip_type) {
+	case INV_MPU6050:
+	case INV_MPU6000:
+	case INV_MPU9150:
+		/* old chips: switch clock manually */
+		ret = inv_mpu6050_pwr_mgmt_1_write(st, false, clock, -1);
+		if (ret)
+			return ret;
+		st->chip_config.clk = clock;
+		break;
+	default:
+		/* automatic clock switching, nothing to do */
+		break;
+	}
+
+	return 0;
+}
 
-		mgmt_1 &= ~INV_MPU6050_BIT_CLK_MASK;
+int inv_mpu6050_switch_engine(struct inv_mpu6050_state *st, bool en,
+			      unsigned int mask)
+{
+	unsigned int sleep;
+	u8 pwr_mgmt2, user_ctrl;
+	int ret;
+
+	/* delete useless requests */
+	if (mask & INV_MPU6050_SENSOR_ACCL && en == st->chip_config.accl_en)
+		mask &= ~INV_MPU6050_SENSOR_ACCL;
+	if (mask & INV_MPU6050_SENSOR_GYRO && en == st->chip_config.gyro_en)
+		mask &= ~INV_MPU6050_SENSOR_GYRO;
+	if (mask & INV_MPU6050_SENSOR_TEMP && en == st->chip_config.temp_en)
+		mask &= ~INV_MPU6050_SENSOR_TEMP;
+	if (mask & INV_MPU6050_SENSOR_MAGN && en == st->chip_config.magn_en)
+		mask &= ~INV_MPU6050_SENSOR_MAGN;
+	if (mask == 0)
+		return 0;
+
+	/* turn on/off temperature sensor */
+	if (mask & INV_MPU6050_SENSOR_TEMP) {
+		ret = inv_mpu6050_pwr_mgmt_1_write(st, false, -1, !en);
+		if (ret)
+			return ret;
+		st->chip_config.temp_en = en;
 	}
 
-	if ((mask == INV_MPU6050_BIT_PWR_GYRO_STBY) && (!en)) {
-		/*
-		 * turning off gyro requires switch to internal clock first.
-		 * Then turn off gyro engine
-		 */
-		mgmt_1 |= INV_CLK_INTERNAL;
-		result = regmap_write(st->map, st->reg->pwr_mgmt_1, mgmt_1);
-		if (result)
-			return result;
+	/* update user_crtl for driving magnetometer */
+	if (mask & INV_MPU6050_SENSOR_MAGN) {
+		user_ctrl = st->chip_config.user_ctrl;
+		if (en)
+			user_ctrl |= INV_MPU6050_BIT_I2C_MST_EN;
+		else
+			user_ctrl &= ~INV_MPU6050_BIT_I2C_MST_EN;
+		ret = regmap_write(st->map, st->reg->user_ctrl, user_ctrl);
+		if (ret)
+			return ret;
+		st->chip_config.user_ctrl = user_ctrl;
+		st->chip_config.magn_en = en;
 	}
 
-	result = regmap_read(st->map, st->reg->pwr_mgmt_2, &d);
-	if (result)
-		return result;
-	if (en)
-		d &= ~mask;
-	else
-		d |= mask;
-	result = regmap_write(st->map, st->reg->pwr_mgmt_2, d);
-	if (result)
-		return result;
+	/* manage accel & gyro engines */
+	if (mask & (INV_MPU6050_SENSOR_ACCL | INV_MPU6050_SENSOR_GYRO)) {
+		/* compute power management 2 current value */
+		pwr_mgmt2 = 0;
+		if (!st->chip_config.accl_en)
+			pwr_mgmt2 |= INV_MPU6050_BIT_PWR_ACCL_STBY;
+		if (!st->chip_config.gyro_en)
+			pwr_mgmt2 |= INV_MPU6050_BIT_PWR_GYRO_STBY;
+
+		/* update to new requested value */
+		if (mask & INV_MPU6050_SENSOR_ACCL) {
+			if (en)
+				pwr_mgmt2 &= ~INV_MPU6050_BIT_PWR_ACCL_STBY;
+			else
+				pwr_mgmt2 |= INV_MPU6050_BIT_PWR_ACCL_STBY;
+		}
+		if (mask & INV_MPU6050_SENSOR_GYRO) {
+			if (en)
+				pwr_mgmt2 &= ~INV_MPU6050_BIT_PWR_GYRO_STBY;
+			else
+				pwr_mgmt2 |= INV_MPU6050_BIT_PWR_GYRO_STBY;
+		}
 
-	if (en) {
-		/* Wait for output to stabilize */
-		msleep(INV_MPU6050_TEMP_UP_TIME);
-		if (mask == INV_MPU6050_BIT_PWR_GYRO_STBY) {
-			/* switch internal clock to PLL */
-			mgmt_1 |= INV_CLK_PLL;
-			result = regmap_write(st->map,
-					      st->reg->pwr_mgmt_1, mgmt_1);
-			if (result)
-				return result;
+		/* switch clock to internal when turning gyro off */
+		if (mask & INV_MPU6050_SENSOR_GYRO && !en) {
+			ret = inv_mpu6050_clock_switch(st, INV_CLK_INTERNAL);
+			if (ret)
+				return ret;
+		}
+
+		/* update sensors engine */
+		dev_dbg(regmap_get_device(st->map), "pwr_mgmt_2: 0x%x\n",
+			pwr_mgmt2);
+		ret = regmap_write(st->map, st->reg->pwr_mgmt_2, pwr_mgmt2);
+		if (ret)
+			return ret;
+		if (mask & INV_MPU6050_SENSOR_ACCL)
+			st->chip_config.accl_en = en;
+		if (mask & INV_MPU6050_SENSOR_GYRO)
+			st->chip_config.gyro_en = en;
+
+		/* compute required time to have sensors stabilized */
+		sleep = 0;
+		if (en) {
+			if (mask & INV_MPU6050_SENSOR_ACCL) {
+				if (sleep < INV_MPU6050_ACCEL_UP_TIME)
+					sleep = INV_MPU6050_ACCEL_UP_TIME;
+			}
+			if (mask & INV_MPU6050_SENSOR_GYRO) {
+				if (sleep < INV_MPU6050_GYRO_UP_TIME)
+					sleep = INV_MPU6050_GYRO_UP_TIME;
+			}
+		} else {
+			if (mask & INV_MPU6050_SENSOR_GYRO) {
+				if (sleep < INV_MPU6050_GYRO_DOWN_TIME)
+					sleep = INV_MPU6050_GYRO_DOWN_TIME;
+			}
+		}
+		if (sleep)
+			msleep(sleep);
+
+		/* switch clock to PLL when turning gyro on */
+		if (mask & INV_MPU6050_SENSOR_GYRO && en) {
+			ret = inv_mpu6050_clock_switch(st, INV_CLK_PLL);
+			if (ret)
+				return ret;
 		}
 	}
 
@@ -279,7 +402,7 @@ int inv_mpu6050_set_power_itg(struct inv_mpu6050_state *st, bool power_on)
 
 	if (power_on) {
 		if (!st->powerup_count) {
-			result = regmap_write(st->map, st->reg->pwr_mgmt_1, 0);
+			result = inv_mpu6050_pwr_mgmt_1_write(st, false, -1, -1);
 			if (result)
 				return result;
 			usleep_range(INV_MPU6050_REG_UP_TIME_MIN,
@@ -288,8 +411,7 @@ int inv_mpu6050_set_power_itg(struct inv_mpu6050_state *st, bool power_on)
 		st->powerup_count++;
 	} else {
 		if (st->powerup_count == 1) {
-			result = regmap_write(st->map, st->reg->pwr_mgmt_1,
-					      INV_MPU6050_BIT_SLEEP);
+			result = inv_mpu6050_pwr_mgmt_1_write(st, true, -1, -1);
 			if (result)
 				return result;
 		}
@@ -451,33 +573,41 @@ static int inv_mpu6050_read_channel_data(struct iio_dev *indio_dev,
 	switch (chan->type) {
 	case IIO_ANGL_VEL:
 		result = inv_mpu6050_switch_engine(st, true,
-				INV_MPU6050_BIT_PWR_GYRO_STBY);
+				INV_MPU6050_SENSOR_GYRO);
 		if (result)
 			goto error_power_off;
 		ret = inv_mpu6050_sensor_show(st, st->reg->raw_gyro,
 					      chan->channel2, val);
 		result = inv_mpu6050_switch_engine(st, false,
-				INV_MPU6050_BIT_PWR_GYRO_STBY);
+				INV_MPU6050_SENSOR_GYRO);
 		if (result)
 			goto error_power_off;
 		break;
 	case IIO_ACCEL:
 		result = inv_mpu6050_switch_engine(st, true,
-				INV_MPU6050_BIT_PWR_ACCL_STBY);
+				INV_MPU6050_SENSOR_ACCL);
 		if (result)
 			goto error_power_off;
 		ret = inv_mpu6050_sensor_show(st, st->reg->raw_accl,
 					      chan->channel2, val);
 		result = inv_mpu6050_switch_engine(st, false,
-				INV_MPU6050_BIT_PWR_ACCL_STBY);
+				INV_MPU6050_SENSOR_ACCL);
 		if (result)
 			goto error_power_off;
 		break;
 	case IIO_TEMP:
+		result = inv_mpu6050_switch_engine(st, true,
+				INV_MPU6050_SENSOR_TEMP);
+		if (result)
+			goto error_power_off;
 		/* wait for stablization */
-		msleep(INV_MPU6050_SENSOR_UP_TIME);
+		msleep(INV_MPU6050_TEMP_UP_TIME);
 		ret = inv_mpu6050_sensor_show(st, st->reg->temperature,
 					      IIO_MOD_X, val);
+		result = inv_mpu6050_switch_engine(st, false,
+				INV_MPU6050_SENSOR_TEMP);
+		if (result)
+			goto error_power_off;
 		break;
 	case IIO_MAGN:
 		ret = inv_mpu_magn_read(st, chan->channel2, val);
@@ -1108,7 +1238,7 @@ static const struct iio_info mpu_info = {
 static int inv_check_and_setup_chip(struct inv_mpu6050_state *st)
 {
 	int result;
-	unsigned int regval;
+	unsigned int regval, mask;
 	int i;
 
 	st->hw  = &hw_info[st->chip_type];
@@ -1174,13 +1304,9 @@ static int inv_check_and_setup_chip(struct inv_mpu6050_state *st)
 	result = inv_mpu6050_set_power_itg(st, true);
 	if (result)
 		return result;
-
-	result = inv_mpu6050_switch_engine(st, false,
-					   INV_MPU6050_BIT_PWR_ACCL_STBY);
-	if (result)
-		goto error_power_off;
-	result = inv_mpu6050_switch_engine(st, false,
-					   INV_MPU6050_BIT_PWR_GYRO_STBY);
+	mask = INV_MPU6050_SENSOR_ACCL | INV_MPU6050_SENSOR_GYRO |
+			INV_MPU6050_SENSOR_TEMP | INV_MPU6050_SENSOR_MAGN;
+	result = inv_mpu6050_switch_engine(st, false, mask);
 	if (result)
 		goto error_power_off;
 
diff --git a/drivers/iio/imu/inv_mpu6050/inv_mpu_iio.h b/drivers/iio/imu/inv_mpu6050/inv_mpu_iio.h
index 17f1f6a15f95..a578789c9210 100644
--- a/drivers/iio/imu/inv_mpu6050/inv_mpu_iio.h
+++ b/drivers/iio/imu/inv_mpu6050/inv_mpu_iio.h
@@ -83,11 +83,22 @@ enum inv_devices {
 	INV_NUM_PARTS
 };
 
+/* chip sensors mask: accelerometer, gyroscope, temperature, magnetometer */
+#define INV_MPU6050_SENSOR_ACCL		BIT(0)
+#define INV_MPU6050_SENSOR_GYRO		BIT(1)
+#define INV_MPU6050_SENSOR_TEMP		BIT(2)
+#define INV_MPU6050_SENSOR_MAGN		BIT(3)
+
 /**
  *  struct inv_mpu6050_chip_config - Cached chip configuration data.
+ *  @clk:		selected chip clock
  *  @fsr:		Full scale range.
  *  @lpf:		Digital low pass filter frequency.
  *  @accl_fs:		accel full scale range.
+ *  @accl_en:		accel engine enabled
+ *  @gyro_en:		gyro engine enabled
+ *  @temp_en:		temperature sensor enabled
+ *  @magn_en:		magn engine (i2c master) enabled
  *  @accl_fifo_enable:	enable accel data output
  *  @gyro_fifo_enable:	enable gyro data output
  *  @temp_fifo_enable:	enable temp data output
@@ -95,9 +106,14 @@ enum inv_devices {
  *  @divider:		chip sample rate divider (sample rate divider - 1)
  */
 struct inv_mpu6050_chip_config {
+	unsigned int clk:3;
 	unsigned int fsr:2;
 	unsigned int lpf:3;
 	unsigned int accl_fs:2;
+	unsigned int accl_en:1;
+	unsigned int gyro_en:1;
+	unsigned int temp_en:1;
+	unsigned int magn_en:1;
 	unsigned int accl_fifo_enable:1;
 	unsigned int gyro_fifo_enable:1;
 	unsigned int temp_fifo_enable:1;
@@ -262,6 +278,7 @@ struct inv_mpu6050_state {
 #define INV_MPU6050_REG_PWR_MGMT_1          0x6B
 #define INV_MPU6050_BIT_H_RESET             0x80
 #define INV_MPU6050_BIT_SLEEP               0x40
+#define INV_MPU6050_BIT_TEMP_DIS            0x08
 #define INV_MPU6050_BIT_CLK_MASK            0x7
 
 #define INV_MPU6050_REG_PWR_MGMT_2          0x6C
@@ -292,7 +309,9 @@ struct inv_mpu6050_state {
 /* delay time in milliseconds */
 #define INV_MPU6050_POWER_UP_TIME            100
 #define INV_MPU6050_TEMP_UP_TIME             100
-#define INV_MPU6050_SENSOR_UP_TIME           30
+#define INV_MPU6050_ACCEL_UP_TIME            20
+#define INV_MPU6050_GYRO_UP_TIME             35
+#define INV_MPU6050_GYRO_DOWN_TIME           150
 
 /* delay time in microseconds */
 #define INV_MPU6050_REG_UP_TIME_MIN          5000
@@ -417,7 +436,8 @@ enum inv_mpu6050_clock_sel_e {
 irqreturn_t inv_mpu6050_read_fifo(int irq, void *p);
 int inv_mpu6050_probe_trigger(struct iio_dev *indio_dev, int irq_type);
 int inv_reset_fifo(struct iio_dev *indio_dev);
-int inv_mpu6050_switch_engine(struct inv_mpu6050_state *st, bool en, u32 mask);
+int inv_mpu6050_switch_engine(struct inv_mpu6050_state *st, bool en,
+			      unsigned int mask);
 int inv_mpu6050_write_reg(struct inv_mpu6050_state *st, int reg, u8 val);
 int inv_mpu6050_set_power_itg(struct inv_mpu6050_state *st, bool power_on);
 int inv_mpu_acpi_create_mux_client(struct i2c_client *client);
diff --git a/drivers/iio/imu/inv_mpu6050/inv_mpu_magn.c b/drivers/iio/imu/inv_mpu6050/inv_mpu_magn.c
index 607104a2631e..3f402fa56d95 100644
--- a/drivers/iio/imu/inv_mpu6050/inv_mpu_magn.c
+++ b/drivers/iio/imu/inv_mpu6050/inv_mpu_magn.c
@@ -316,9 +316,9 @@ int inv_mpu_magn_set_orient(struct inv_mpu6050_state *st)
  *
  * Returns 0 on success, a negative error code otherwise
  */
-int inv_mpu_magn_read(const struct inv_mpu6050_state *st, int axis, int *val)
+int inv_mpu_magn_read(struct inv_mpu6050_state *st, int axis, int *val)
 {
-	unsigned int user_ctrl, status;
+	unsigned int status;
 	__be16 data;
 	uint8_t addr;
 	unsigned int freq_hz, period_ms;
@@ -350,16 +350,14 @@ int inv_mpu_magn_read(const struct inv_mpu6050_state *st, int axis, int *val)
 		freq_hz = INV_MPU_MAGN_FREQ_HZ_MAX;
 	period_ms = 1000 / freq_hz;
 
-	/* start i2c master, wait for xfer, stop */
-	user_ctrl = st->chip_config.user_ctrl | INV_MPU6050_BIT_I2C_MST_EN;
-	ret = regmap_write(st->map, st->reg->user_ctrl, user_ctrl);
+	ret = inv_mpu6050_switch_engine(st, true, INV_MPU6050_SENSOR_MAGN);
 	if (ret)
 		return ret;
 
 	/* need to wait 2 periods + half-period margin */
 	msleep(period_ms * 2 + period_ms / 2);
-	user_ctrl = st->chip_config.user_ctrl;
-	ret = regmap_write(st->map, st->reg->user_ctrl, user_ctrl);
+
+	ret = inv_mpu6050_switch_engine(st, false, INV_MPU6050_SENSOR_MAGN);
 	if (ret)
 		return ret;
 
diff --git a/drivers/iio/imu/inv_mpu6050/inv_mpu_magn.h b/drivers/iio/imu/inv_mpu6050/inv_mpu_magn.h
index b41bd0578478..f7ad50ca6c1b 100644
--- a/drivers/iio/imu/inv_mpu6050/inv_mpu_magn.h
+++ b/drivers/iio/imu/inv_mpu6050/inv_mpu_magn.h
@@ -31,6 +31,6 @@ int inv_mpu_magn_set_rate(const struct inv_mpu6050_state *st, int fifo_rate);
 
 int inv_mpu_magn_set_orient(struct inv_mpu6050_state *st);
 
-int inv_mpu_magn_read(const struct inv_mpu6050_state *st, int axis, int *val);
+int inv_mpu_magn_read(struct inv_mpu6050_state *st, int axis, int *val);
 
 #endif		/* INV_MPU_MAGN_H_ */
diff --git a/drivers/iio/imu/inv_mpu6050/inv_mpu_trigger.c b/drivers/iio/imu/inv_mpu6050/inv_mpu_trigger.c
index 5199fe790c30..cfd7243159f6 100644
--- a/drivers/iio/imu/inv_mpu6050/inv_mpu_trigger.c
+++ b/drivers/iio/imu/inv_mpu6050/inv_mpu_trigger.c
@@ -5,9 +5,10 @@
 
 #include "inv_mpu_iio.h"
 
-static void inv_scan_query_mpu6050(struct iio_dev *indio_dev)
+static unsigned int inv_scan_query_mpu6050(struct iio_dev *indio_dev)
 {
 	struct inv_mpu6050_state  *st = iio_priv(indio_dev);
+	unsigned int mask;
 
 	st->chip_config.gyro_fifo_enable =
 		test_bit(INV_MPU6050_SCAN_GYRO_X,
@@ -27,17 +28,28 @@ static void inv_scan_query_mpu6050(struct iio_dev *indio_dev)
 
 	st->chip_config.temp_fifo_enable =
 		test_bit(INV_MPU6050_SCAN_TEMP, indio_dev->active_scan_mask);
+
+	mask = 0;
+	if (st->chip_config.gyro_fifo_enable)
+		mask |= INV_MPU6050_SENSOR_GYRO;
+	if (st->chip_config.accl_fifo_enable)
+		mask |= INV_MPU6050_SENSOR_ACCL;
+	if (st->chip_config.temp_fifo_enable)
+		mask |= INV_MPU6050_SENSOR_TEMP;
+
+	return mask;
 }
 
-static void inv_scan_query_mpu9x50(struct iio_dev *indio_dev)
+static unsigned int inv_scan_query_mpu9x50(struct iio_dev *indio_dev)
 {
 	struct inv_mpu6050_state *st = iio_priv(indio_dev);
+	unsigned int mask;
 
-	inv_scan_query_mpu6050(indio_dev);
+	mask = inv_scan_query_mpu6050(indio_dev);
 
 	/* no magnetometer if i2c auxiliary bus is used */
 	if (st->magn_disabled)
-		return;
+		return mask;
 
 	st->chip_config.magn_fifo_enable =
 		test_bit(INV_MPU9X50_SCAN_MAGN_X,
@@ -46,9 +58,13 @@ static void inv_scan_query_mpu9x50(struct iio_dev *indio_dev)
 			 indio_dev->active_scan_mask) ||
 		test_bit(INV_MPU9X50_SCAN_MAGN_Z,
 			 indio_dev->active_scan_mask);
+	if (st->chip_config.magn_fifo_enable)
+		mask |= INV_MPU6050_SENSOR_MAGN;
+
+	return mask;
 }
 
-static void inv_scan_query(struct iio_dev *indio_dev)
+static unsigned int inv_scan_query(struct iio_dev *indio_dev)
 {
 	struct inv_mpu6050_state *st = iio_priv(indio_dev);
 
@@ -92,62 +108,40 @@ static unsigned int inv_compute_skip_samples(const struct inv_mpu6050_state *st)
 static int inv_mpu6050_set_enable(struct iio_dev *indio_dev, bool enable)
 {
 	struct inv_mpu6050_state *st = iio_priv(indio_dev);
-	uint8_t d;
+	unsigned int scan;
 	int result;
 
+	scan = inv_scan_query(indio_dev);
+
 	if (enable) {
 		result = inv_mpu6050_set_power_itg(st, true);
 		if (result)
 			return result;
-		inv_scan_query(indio_dev);
-		if (st->chip_config.gyro_fifo_enable) {
-			result = inv_mpu6050_switch_engine(st, true,
-					INV_MPU6050_BIT_PWR_GYRO_STBY);
-			if (result)
-				goto error_power_off;
-		}
-		if (st->chip_config.accl_fifo_enable) {
-			result = inv_mpu6050_switch_engine(st, true,
-					INV_MPU6050_BIT_PWR_ACCL_STBY);
-			if (result)
-				goto error_gyro_off;
-		}
-		if (st->chip_config.magn_fifo_enable) {
-			d = st->chip_config.user_ctrl |
-					INV_MPU6050_BIT_I2C_MST_EN;
-			result = regmap_write(st->map, st->reg->user_ctrl, d);
-			if (result)
-				goto error_accl_off;
-			st->chip_config.user_ctrl = d;
-		}
+		result = inv_mpu6050_switch_engine(st, true, scan);
+		if (result)
+			goto error_power_off;
 		st->skip_samples = inv_compute_skip_samples(st);
 		result = inv_reset_fifo(indio_dev);
 		if (result)
-			goto error_magn_off;
+			goto error_sensors_off;
 	} else {
 		result = regmap_write(st->map, st->reg->fifo_en, 0);
 		if (result)
-			goto error_magn_off;
+			goto error_fifo_off;
 
 		result = regmap_write(st->map, st->reg->int_enable, 0);
 		if (result)
-			goto error_magn_off;
-
-		d = st->chip_config.user_ctrl & ~INV_MPU6050_BIT_I2C_MST_EN;
-		result = regmap_write(st->map, st->reg->user_ctrl, d);
-		if (result)
-			goto error_magn_off;
-		st->chip_config.user_ctrl = d;
+			goto error_fifo_off;
 
-		result = inv_mpu6050_switch_engine(st, false,
-					INV_MPU6050_BIT_PWR_ACCL_STBY);
+		/* restore user_ctrl for disabling FIFO reading */
+		result = regmap_write(st->map, st->reg->user_ctrl,
+				      st->chip_config.user_ctrl);
 		if (result)
-			goto error_accl_off;
+			goto error_sensors_off;
 
-		result = inv_mpu6050_switch_engine(st, false,
-					INV_MPU6050_BIT_PWR_GYRO_STBY);
+		result = inv_mpu6050_switch_engine(st, false, scan);
 		if (result)
-			goto error_gyro_off;
+			goto error_power_off;
 
 		result = inv_mpu6050_set_power_itg(st, false);
 		if (result)
@@ -156,18 +150,11 @@ static int inv_mpu6050_set_enable(struct iio_dev *indio_dev, bool enable)
 
 	return 0;
 
-error_magn_off:
+error_fifo_off:
 	/* always restore user_ctrl to disable fifo properly */
-	st->chip_config.user_ctrl &= ~INV_MPU6050_BIT_I2C_MST_EN;
 	regmap_write(st->map, st->reg->user_ctrl, st->chip_config.user_ctrl);
-error_accl_off:
-	if (st->chip_config.accl_fifo_enable)
-		inv_mpu6050_switch_engine(st, false,
-					  INV_MPU6050_BIT_PWR_ACCL_STBY);
-error_gyro_off:
-	if (st->chip_config.gyro_fifo_enable)
-		inv_mpu6050_switch_engine(st, false,
-					  INV_MPU6050_BIT_PWR_GYRO_STBY);
+error_sensors_off:
+	inv_mpu6050_switch_engine(st, false, scan);
 error_power_off:
 	inv_mpu6050_set_power_itg(st, false);
 	return result;
-- 
2.17.1