iio: imu: inv_mpu6050: use runtime pm with autosuspend

Use runtime power management for handling chip power and
sensor engines on/off. Simplifies things a lot since pm
runtime already has reference counter.
Usage of autosuspend reduces the number of power on/off. This
makes polling interface now usable to get data at low
frequency.
Signed-off-by: Jean-Baptiste Maneyrol <jmaneyrol@invensense.com>
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>

drivers/iio/imu/inv_mpu6050/inv_mpu_iio.h

@@ -164,6 +164,7 @@ struct inv_mpu6050_hw {
  *  @magn_disabled:     magnetometer disabled for backward compatibility reason.
  *  @magn_raw_to_gauss:	coefficient to convert mag raw value to Gauss.
  *  @magn_orient:       magnetometer sensor chip orientation if available.
+ *  @suspended_sensors:	sensors mask of sensors turned off for suspend
  */
 struct inv_mpu6050_state {
 	struct mutex lock;
@@ -174,7 +175,6 @@ struct inv_mpu6050_state {
 	enum   inv_devices chip_type;
 	struct i2c_mux_core *muxc;
 	struct i2c_client *mux_client;
-	unsigned int powerup_count;
 	struct inv_mpu6050_platform_data plat_data;
 	struct iio_mount_matrix orientation;
 	struct regmap *map;
@@ -189,6 +189,7 @@ struct inv_mpu6050_state {
 	bool magn_disabled;
 	s32 magn_raw_to_gauss[3];
 	struct iio_mount_matrix magn_orient;
+	unsigned int suspended_sensors;
 };
 
 /*register and associated bit definition*/
@@ -312,6 +313,7 @@ struct inv_mpu6050_state {
 #define INV_MPU6050_ACCEL_UP_TIME            20
 #define INV_MPU6050_GYRO_UP_TIME             35
 #define INV_MPU6050_GYRO_DOWN_TIME           150
+#define INV_MPU6050_SUSPEND_DELAY_MS         2000
 
 /* delay time in microseconds */
 #define INV_MPU6050_REG_UP_TIME_MIN          5000
@@ -439,7 +441,6 @@ int inv_mpu6050_prepare_fifo(struct inv_mpu6050_state *st, bool enable);
 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);
 void inv_mpu_acpi_delete_mux_client(struct i2c_client *client);
 int inv_mpu_core_probe(struct regmap *regmap, int irq, const char *name,

drivers/iio/imu/inv_mpu6050/inv_mpu_trigger.c

@@ -3,6 +3,7 @@
 * Copyright (C) 2012 Invensense, Inc.
 */
 
+#include <linux/pm_runtime.h>
 #include "inv_mpu_iio.h"
 
 static unsigned int inv_scan_query_mpu6050(struct iio_dev *indio_dev)
@@ -156,41 +157,43 @@ int inv_mpu6050_prepare_fifo(struct inv_mpu6050_state *st, bool enable)
 static int inv_mpu6050_set_enable(struct iio_dev *indio_dev, bool enable)
 {
 	struct inv_mpu6050_state *st = iio_priv(indio_dev);
+	struct device *pdev = regmap_get_device(st->map);
 	unsigned int scan;
 	int result;
 
-	scan = inv_scan_query(indio_dev);
-
 	if (enable) {
-		result = inv_mpu6050_set_power_itg(st, true);
-		if (result)
+		scan = inv_scan_query(indio_dev);
+		result = pm_runtime_get_sync(pdev);
+		if (result < 0) {
+			pm_runtime_put_noidle(pdev);
 			return result;
+		}
+		/*
+		 * In case autosuspend didn't trigger, turn off first not
+		 * required sensors.
+		 */
+		result = inv_mpu6050_switch_engine(st, false, ~scan);
+		if (result)
+			goto error_power_off;
 		result = inv_mpu6050_switch_engine(st, true, scan);
 		if (result)
 			goto error_power_off;
 		st->skip_samples = inv_compute_skip_samples(st);
 		result = inv_mpu6050_prepare_fifo(st, true);
 		if (result)
-			goto error_sensors_off;
+			goto error_power_off;
 	} else {
 		result = inv_mpu6050_prepare_fifo(st, false);
-		if (result)
-			goto error_sensors_off;
-		result = inv_mpu6050_switch_engine(st, false, scan);
-		if (result)
-			goto error_power_off;
-
-		result = inv_mpu6050_set_power_itg(st, false);
 		if (result)
 			goto error_power_off;
+		pm_runtime_mark_last_busy(pdev);
+		pm_runtime_put_autosuspend(pdev);
 	}
 
 	return 0;
 
-error_sensors_off:
-	inv_mpu6050_switch_engine(st, false, scan);
 error_power_off:
-	inv_mpu6050_set_power_itg(st, false);
+	pm_runtime_put_autosuspend(pdev);
 	return result;
 }