iio: imu: st_lsm6dsx: fix PM support for st_lsm6dsx i2c controller

Properly suspend/resume i2c slaves connected to st_lsm6dsx master
controller if the CPU goes in suspended state

Fixes: c91c1c844ebd ("imu: st_lsm6dsx: add i2c embedded controller support")
Signed-off-by: Lorenzo Bianconi <[e-mail]>
Cc: <[e-mail]>
Signed-off-by: Jonathan Cameron <[e-mail]>

drivers/iio/imu/st_lsm6dsx/st_lsm6dsx.h

···
  * @conf_lock: Mutex to prevent concurrent FIFO configuration update.
  * @page_lock: Mutex to prevent concurrent memory page configuration.
  * @fifo_mode: FIFO operating mode supported by the device.
+ * @suspend_mask: Suspended sensor bitmask.
  * @enable_mask: Enabled sensor bitmask.
  * @ts_sip: Total number of timestamp samples in a given pattern.
  * @sip: Total number of samples (acc/gyro/ts) in a given pattern.
···
 	struct mutex page_lock;
 
 	enum st_lsm6dsx_fifo_mode fifo_mode;
+	u8 suspend_mask;
 	u8 enable_mask;
 	u8 ts_sip;
 	u8 sip;

drivers/iio/imu/st_lsm6dsx/st_lsm6dsx_core.c

···
 {
 	struct st_lsm6dsx_hw *hw = dev_get_drvdata(dev);
 	struct st_lsm6dsx_sensor *sensor;
-	const struct st_lsm6dsx_reg *reg;
-	unsigned int data;
 	int i, err = 0;
 
 	for (i = 0; i < ST_LSM6DSX_ID_MAX; i++) {
···
 		if (!(hw->enable_mask & BIT(sensor->id)))
 			continue;
 
-		reg = &st_lsm6dsx_odr_table[sensor->id].reg;
-		data = ST_LSM6DSX_SHIFT_VAL(0, reg->mask);
-		err = st_lsm6dsx_update_bits_locked(hw, reg->addr, reg->mask,
-						    data);
+		if (sensor->id == ST_LSM6DSX_ID_EXT0 ||
+		    sensor->id == ST_LSM6DSX_ID_EXT1 ||
+		    sensor->id == ST_LSM6DSX_ID_EXT2)
+			err = st_lsm6dsx_shub_set_enable(sensor, false);
+		else
+			err = st_lsm6dsx_sensor_set_enable(sensor, false);
 		if (err < 0)
 			return err;
+
+		hw->suspend_mask |= BIT(sensor->id);
 	}
 
 	if (hw->fifo_mode != ST_LSM6DSX_FIFO_BYPASS)
···
 			continue;
 
 		sensor = iio_priv(hw->iio_devs[i]);
-		if (!(hw->enable_mask & BIT(sensor->id)))
+		if (!(hw->suspend_mask & BIT(sensor->id)))
 			continue;
 
-		err = st_lsm6dsx_set_odr(sensor, sensor->odr);
+		if (sensor->id == ST_LSM6DSX_ID_EXT0 ||
+		    sensor->id == ST_LSM6DSX_ID_EXT1 ||
+		    sensor->id == ST_LSM6DSX_ID_EXT2)
+			err = st_lsm6dsx_shub_set_enable(sensor, true);
+		else
+			err = st_lsm6dsx_sensor_set_enable(sensor, true);
 		if (err < 0)
 			return err;
+
+		hw->suspend_mask &= ~BIT(sensor->id);
 	}
 
 	if (hw->enable_mask)