iio: accel: mma9551: Add runtime pm support

Add support for runtime pm to reduce the power consumed by the device
when not used.

If CONFIG_PM is not enabled, the device will be powered on at
init and only powered off on system suspend.

If CONFIG_PM is enabled, runtime pm autosuspend is used:
- for raw reads will keep the device on for a specified time
- for events it will keep the device on as long as we have at least
one event active

Signed-off-by: Irina Tirdea <irina.tirdea@intel.com>
Reviewed-by: Vlad Dogaru <vlad.dogaru@intel.com>
Signed-off-by: Jonathan Cameron <jic23@kernel.org>

drivers/iio/accel/mma9551.c

@@ -22,6 +22,7 @@
 #include <linux/iio/iio.h>
 #include <linux/iio/sysfs.h>
 #include <linux/iio/events.h>
+#include <linux/pm_runtime.h>
 
 #define MMA9551_DRV_NAME		"mma9551"
 #define MMA9551_IRQ_NAME		"mma9551_event"
@@ -71,6 +72,7 @@ enum mma9551_gpio_pin {
 /* Sleep/Wake application */
 #define MMA9551_SLEEP_CFG		0x06
 #define MMA9551_SLEEP_CFG_SNCEN		BIT(0)
+#define MMA9551_SLEEP_CFG_FLEEN		BIT(1)
 #define MMA9551_SLEEP_CFG_SCHEN		BIT(2)
 
 /* AFE application */
@@ -114,6 +116,9 @@ enum mma9551_tilt_axis {
 #define MMA9551_I2C_READ_RETRIES	5
 #define MMA9551_I2C_READ_DELAY	50	/* us */
 
+#define MMA9551_DEFAULT_SAMPLE_RATE	122	/* Hz */
+#define MMA9551_AUTO_SUSPEND_DELAY_MS	2000
+
 struct mma9551_mbox_request {
 	u8 start_mbox;		/* Always 0. */
 	u8 app_id;
@@ -387,16 +392,55 @@ static int mma9551_read_version(struct i2c_client *client)
 }
 
 /*
+ * Power on chip and enable doze mode.
  * Use 'false' as the second parameter to cause the device to enter
  * sleep.
  */
-static int mma9551_set_device_state(struct i2c_client *client,
+static int mma9551_set_device_state(struct i2c_client *client, bool enable)
-				    bool enable)
 {
 	return mma9551_update_config_bits(client, MMA9551_APPID_SLEEP_WAKE,
 					  MMA9551_SLEEP_CFG,
-					  MMA9551_SLEEP_CFG_SNCEN,
+					  MMA9551_SLEEP_CFG_SNCEN |
-					  enable ? 0 : MMA9551_SLEEP_CFG_SNCEN);
+					  MMA9551_SLEEP_CFG_FLEEN |
+					  MMA9551_SLEEP_CFG_SCHEN,
+					  enable ? MMA9551_SLEEP_CFG_SCHEN |
+					  MMA9551_SLEEP_CFG_FLEEN :
+					  MMA9551_SLEEP_CFG_SNCEN);
+}
+
+static int mma9551_set_power_state(struct i2c_client *client, bool on)
+{
+#ifdef CONFIG_PM
+	int ret;
+
+	if (on)
+		ret = pm_runtime_get_sync(&client->dev);
+	else {
+		pm_runtime_mark_last_busy(&client->dev);
+		ret = pm_runtime_put_autosuspend(&client->dev);
+	}
+
+	if (ret < 0) {
+		dev_err(&client->dev,
+			"failed to change power state to %d\n", on);
+		if (on)
+			pm_runtime_put_noidle(&client->dev);
+
+		return ret;
+	}
+#endif
+
+	return 0;
+}
+
+static void mma9551_sleep(int freq)
+{
+	int sleep_val = 1000 / freq;
+
+	if (sleep_val < 20)
+		usleep_range(sleep_val * 1000, 20000);
+	else
+		msleep_interruptible(sleep_val);
 }
 
 static int mma9551_read_incli_chan(struct i2c_client *client,
@@ -424,15 +468,19 @@ static int mma9551_read_incli_chan(struct i2c_client *client,
 		return -EINVAL;
 	}
 
-	ret = mma9551_read_status_byte(client, MMA9551_APPID_TILT,
+	ret = mma9551_set_power_state(client, true);
-				       reg_addr, &angle);
 	if (ret < 0)
 		return ret;
 
+	ret = mma9551_read_status_byte(client, MMA9551_APPID_TILT,
+				       reg_addr, &angle);
+	if (ret < 0)
+		goto out_poweroff;
+
 	ret = mma9551_read_status_byte(client, MMA9551_APPID_TILT,
 				       MMA9551_TILT_QUAD_REG, &quadrant);
 	if (ret < 0)
-		return ret;
+		goto out_poweroff;
 
 	angle &= ~MMA9551_TILT_ANGFLG;
 	quadrant = (quadrant >> quad_shift) & 0x03;
@@ -442,7 +490,11 @@ static int mma9551_read_incli_chan(struct i2c_client *client,
 	else
 		*val = angle + 90 * quadrant;
 
-	return IIO_VAL_INT;
+	ret = IIO_VAL_INT;
+
+out_poweroff:
+	mma9551_set_power_state(client, false);
+	return ret;
 }
 
 static int mma9551_read_accel_chan(struct i2c_client *client,
@@ -467,14 +519,22 @@ static int mma9551_read_accel_chan(struct i2c_client *client,
 		return -EINVAL;
 	}
 
-	ret = mma9551_read_status_word(client, MMA9551_APPID_AFE,
+	ret = mma9551_set_power_state(client, true);
-				       reg_addr, &raw_accel);
 	if (ret < 0)
 		return ret;
 
+	ret = mma9551_read_status_word(client, MMA9551_APPID_AFE,
+				       reg_addr, &raw_accel);
+	if (ret < 0)
+		goto out_poweroff;
+
 	*val = raw_accel;
 
-	return IIO_VAL_INT;
+	ret = IIO_VAL_INT;
+
+out_poweroff:
+	mma9551_set_power_state(client, false);
+	return ret;
 }
 
 static int mma9551_read_raw(struct iio_dev *indio_dev,
@@ -556,6 +616,10 @@ static int mma9551_config_incli_event(struct iio_dev *indio_dev,
 					  MMA9551_APPID_NONE, 0, 0);
 		if (ret < 0)
 			return ret;
+
+		ret = mma9551_set_power_state(data->client, false);
+		if (ret < 0)
+			return ret;
 	} else {
 		int bitnum;
 
@@ -574,12 +638,19 @@ static int mma9551_config_incli_event(struct iio_dev *indio_dev,
 			return -EINVAL;
 		}
 
+
+		ret = mma9551_set_power_state(data->client, true);
+		if (ret < 0)
+			return ret;
+
 		ret = mma9551_gpio_config(data->client,
 					  (enum mma9551_gpio_pin)mma_axis,
 					  MMA9551_APPID_TILT, bitnum, 0);
-		if (ret < 0)
+		if (ret < 0) {
+			mma9551_set_power_state(data->client, false);
 			return ret;
 		}
+	}
 
 	data->event_enabled[mma_axis] = state;
 
@@ -771,12 +842,7 @@ static int mma9551_init(struct mma9551_data *data)
 	if (ret)
 		return ret;
 
-	/* Power on chip and enable doze mode. */
+	return mma9551_set_device_state(data->client, true);
-	return mma9551_update_config_bits(data->client,
-			 MMA9551_APPID_SLEEP_WAKE,
-			 MMA9551_SLEEP_CFG,
-			 MMA9551_SLEEP_CFG_SCHEN | MMA9551_SLEEP_CFG_SNCEN,
-			 MMA9551_SLEEP_CFG_SCHEN);
 }
 
 static int mma9551_gpio_probe(struct iio_dev *indio_dev)
@@ -869,8 +935,19 @@ static int mma9551_probe(struct i2c_client *client,
 		goto out_poweroff;
 	}
 
+	ret = pm_runtime_set_active(&client->dev);
+	if (ret < 0)
+		goto out_iio_unregister;
+
+	pm_runtime_enable(&client->dev);
+	pm_runtime_set_autosuspend_delay(&client->dev,
+					 MMA9551_AUTO_SUSPEND_DELAY_MS);
+	pm_runtime_use_autosuspend(&client->dev);
+
 	return 0;
 
+out_iio_unregister:
+	iio_device_unregister(indio_dev);
 out_poweroff:
 	mma9551_set_device_state(client, false);
 
@@ -882,6 +959,10 @@ static int mma9551_remove(struct i2c_client *client)
 	struct iio_dev *indio_dev = i2c_get_clientdata(client);
 	struct mma9551_data *data = iio_priv(indio_dev);
 
+	pm_runtime_disable(&client->dev);
+	pm_runtime_set_suspended(&client->dev);
+	pm_runtime_put_noidle(&client->dev);
+
 	iio_device_unregister(indio_dev);
 	mutex_lock(&data->mutex);
 	mma9551_set_device_state(data->client, false);
@@ -890,37 +971,72 @@ static int mma9551_remove(struct i2c_client *client)
 	return 0;
 }
 
+#ifdef CONFIG_PM
+static int mma9551_runtime_suspend(struct device *dev)
+{
+	struct iio_dev *indio_dev = i2c_get_clientdata(to_i2c_client(dev));
+	struct mma9551_data *data = iio_priv(indio_dev);
+	int ret;
+
+	mutex_lock(&data->mutex);
+	ret = mma9551_set_device_state(data->client, false);
+	mutex_unlock(&data->mutex);
+	if (ret < 0) {
+		dev_err(&data->client->dev, "powering off device failed\n");
+		return -EAGAIN;
+	}
+
+	return 0;
+}
+
+static int mma9551_runtime_resume(struct device *dev)
+{
+	struct iio_dev *indio_dev = i2c_get_clientdata(to_i2c_client(dev));
+	struct mma9551_data *data = iio_priv(indio_dev);
+	int ret;
+
+	ret = mma9551_set_device_state(data->client, true);
+	if (ret < 0)
+		return ret;
+
+	mma9551_sleep(MMA9551_DEFAULT_SAMPLE_RATE);
+
+	return 0;
+}
+#endif
+
 #ifdef CONFIG_PM_SLEEP
 static int mma9551_suspend(struct device *dev)
 {
 	struct iio_dev *indio_dev = i2c_get_clientdata(to_i2c_client(dev));
 	struct mma9551_data *data = iio_priv(indio_dev);
+	int ret;
 
 	mutex_lock(&data->mutex);
-	mma9551_set_device_state(data->client, false);
+	ret = mma9551_set_device_state(data->client, false);
 	mutex_unlock(&data->mutex);
 
-	return 0;
+	return ret;
 }
 
 static int mma9551_resume(struct device *dev)
 {
 	struct iio_dev *indio_dev = i2c_get_clientdata(to_i2c_client(dev));
 	struct mma9551_data *data = iio_priv(indio_dev);
+	int ret;
 
 	mutex_lock(&data->mutex);
-	mma9551_set_device_state(data->client, true);
+	ret = mma9551_set_device_state(data->client, true);
 	mutex_unlock(&data->mutex);
 
-	return 0;
+	return ret;
 }
-#else
-#define mma9551_suspend NULL
-#define mma9551_resume NULL
 #endif
 
 static const struct dev_pm_ops mma9551_pm_ops = {
 	SET_SYSTEM_SLEEP_PM_OPS(mma9551_suspend, mma9551_resume)
+	SET_RUNTIME_PM_OPS(mma9551_runtime_suspend,
+			   mma9551_runtime_resume, NULL)
 };
 
 static const struct acpi_device_id mma9551_acpi_match[] = {