[PATCH 3/6] iio: accel: kxcjk-1013: support runtime pm

[Srinivas Pandruvada <srinivas.pandruvada@linux.intel.com>]

In an effort to improve raw read performance and at the same time enter
low power state at every possible chance.
For raw reads, it will keep the system powered on for a user specified
max time, this will help read multiple samples without power on/off
sequence.
When runtime pm is not enabled, then it fallbacks to current scheme
of on/off after each read.

Signed-off-by: Srinivas Pandruvada <srinivas.pandruvada@linux.intel.com>
---
 drivers/iio/accel/kxcjk-1013.c | 198 +++++++++++++++++++++++++++++++++--------
 1 file changed, 160 insertions(+), 38 deletions(-)

diff --git a/drivers/iio/accel/kxcjk-1013.c b/drivers/iio/accel/kxcjk-1013.c
index bff5161..4912143 100644
--- a/drivers/iio/accel/kxcjk-1013.c
+++ b/drivers/iio/accel/kxcjk-1013.c
@@ -21,6 +21,8 @@
 #include <linux/string.h>
 #include <linux/acpi.h>
 #include <linux/gpio/consumer.h>
+#include <linux/pm.h>
+#include <linux/pm_runtime.h>
 #include <linux/iio/iio.h>
 #include <linux/iio/sysfs.h>
 #include <linux/iio/buffer.h>
@@ -71,15 +73,21 @@
 #define KXCJK1013_DATA_MASK_12_BIT	0x0FFF
 #define KXCJK1013_MAX_STARTUP_TIME_US	100000
 
+#define KXCJK1013_SLEEP_DELAY_MS	2000
+static int kxcjk1013_power_off_delay_ms = KXCJK1013_SLEEP_DELAY_MS;
+module_param(kxcjk1013_power_off_delay_ms, int, 0644);
+MODULE_PARM_DESC(kxcjk1013_power_off_delay_ms,
+	"KXCJK1013 accelerometer power of delay in milli seconds.");
+
 struct kxcjk1013_data {
 	struct i2c_client *client;
 	struct iio_trigger *trig;
 	bool trig_mode;
 	struct mutex mutex;
 	s16 buffer[8];
-	int power_state;
 	u8 odr_bits;
 	bool active_high_intr;
+	bool trigger_on;
 };
 
 enum kxcjk1013_axis {
@@ -138,6 +146,25 @@ static int kxcjk1013_set_mode(struct kxcjk1013_data *data,
 	return 0;
 }
 
+static int kxcjk1013_get_mode(struct kxcjk1013_data *data,
+			      enum kxcjk1013_mode *mode)
+{
+	int ret;
+
+	ret = i2c_smbus_read_byte_data(data->client, KXCJK1013_REG_CTRL1);
+	if (ret < 0) {
+		dev_err(&data->client->dev, "Error reading reg_ctrl1\n");
+		return ret;
+	}
+
+	if (ret & KXCJK1013_REG_CTRL1_BIT_PC1)
+		*mode = OPERATION;
+	else
+		*mode = STANDBY;
+
+	return 0;
+}
+
 static int kxcjk1013_chip_init(struct kxcjk1013_data *data)
 {
 	int ret;
@@ -204,10 +231,53 @@ static int kxcjk1013_chip_init(struct kxcjk1013_data *data)
 	return 0;
 }
 
+static int kxcjk1013_set_power_state(struct kxcjk1013_data *data, bool on)
+{
+	int ret;
+
+#ifdef CONFIG_PM_RUNTIME
+	if (on)
+		ret = pm_runtime_get_sync(&data->client->dev);
+	else {
+		pm_runtime_put_noidle(&data->client->dev);
+		ret = pm_schedule_suspend(&data->client->dev,
+					  kxcjk1013_power_off_delay_ms);
+	}
+#else
+	if (on) {
+		ret = kxcjk1013_set_mode(data, OPERATION);
+		if (!ret) {
+			int sleep_val;
+
+			sleep_val = kxcjk1013_get_startup_times(data);
+			if (sleep_val < 20000)
+				usleep_range(sleep_val, 20000);
+			else
+				msleep_interruptible(sleep_val/1000);
+
+		}
+	} else
+		ret = kxcjk1013_set_mode(data, STANDBY);
+#endif
+
+	if (ret < 0) {
+		dev_err(&data->client->dev,
+			"Failed: kxcjk1013_set_power_state for %d\n", on);
+		return ret;
+	}
+
+	return 0;
+}
+
 static int kxcjk1013_chip_setup_interrupt(struct kxcjk1013_data *data,
 					  bool status)
 {
 	int ret;
+	enum kxcjk1013_mode store_mode;
+
+	ret = kxcjk1013_get_mode(data, &store_mode);
+	if (ret < 0)
+		return ret;
 
 	/* This is requirement by spec to change state to STANDBY */
 	ret = kxcjk1013_set_mode(data, STANDBY);
@@ -250,7 +320,13 @@ static int kxcjk1013_chip_setup_interrupt(struct kxcjk1013_data *data,
 		return ret;
 	}
 
-	return ret;
+	if (store_mode == OPERATION) {
+		ret = kxcjk1013_set_mode(data, OPERATION);
+		if (ret < 0)
+			return ret;
+	}
+
+	return 0;
 }
 
 static int kxcjk1013_convert_freq_to_bit(int val, int val2)
@@ -271,6 +347,11 @@ static int kxcjk1013_set_odr(struct kxcjk1013_data *data, int val, int val2)
 {
 	int ret;
 	int odr_bits;
+	enum kxcjk1013_mode store_mode;
+
+	ret = kxcjk1013_get_mode(data, &store_mode);
+	if (ret < 0)
+		return ret;
 
 	odr_bits = kxcjk1013_convert_freq_to_bit(val, val2);
 	if (odr_bits < 0)
@@ -290,9 +371,7 @@ static int kxcjk1013_set_odr(struct kxcjk1013_data *data, int val, int val2)
 
 	data->odr_bits = odr_bits;
 
-	/* Check, if the ODR is changed after data enable */
-	if (data->power_state) {
-		/* Set the state back to operation */
+	if (store_mode == OPERATION) {
 		ret = kxcjk1013_set_mode(data, OPERATION);
 		if (ret < 0)
 			return ret;
@@ -356,29 +435,25 @@ static int kxcjk1013_read_raw(struct iio_dev *indio_dev,
 		if (iio_buffer_enabled(indio_dev))
 			ret = -EBUSY;
 		else {
-			int sleep_val;
-
-			ret = kxcjk1013_set_mode(data, OPERATION);
+			ret = kxcjk1013_set_power_state(data, true);
 			if (ret < 0) {
 				mutex_unlock(&data->mutex);
 				return ret;
 			}
-			++data->power_state;
-			sleep_val = kxcjk1013_get_startup_times(data);
-			if (sleep_val < 20000)
-				usleep_range(sleep_val, 20000);
-			else
-				msleep_interruptible(sleep_val/1000);
 			ret = kxcjk1013_get_acc_reg(data, chan->scan_index);
-			if (--data->power_state == 0)
-				kxcjk1013_set_mode(data, STANDBY);
+			if (ret < 0) {
+				kxcjk1013_set_power_state(data, false);
+				mutex_unlock(&data->mutex);
+				return ret;
+			}
+			*val = sign_extend32(ret >> 4, 11);
+			ret = kxcjk1013_set_power_state(data, false);
 		}
 		mutex_unlock(&data->mutex);
 
 		if (ret < 0)
 			return ret;
 
-		*val = sign_extend32(ret >> 4, 11);
 		return IIO_VAL_INT;
 
 	case IIO_CHAN_INFO_SCALE:
@@ -520,20 +595,21 @@ static int kxcjk1013_data_rdy_trigger_set_state(struct iio_trigger *trig,
 {
 	struct iio_dev *indio_dev = iio_trigger_get_drvdata(trig);
 	struct kxcjk1013_data *data = iio_priv(indio_dev);
+	int ret;
+
+	if (state && data->trigger_on)
+		return 0;
 
 	mutex_lock(&data->mutex);
-	if (state) {
-		kxcjk1013_chip_setup_interrupt(data, true);
-		kxcjk1013_set_mode(data, OPERATION);
-		++data->power_state;
-	} else {
-		if (--data->power_state) {
+	ret = kxcjk1013_chip_setup_interrupt(data, state);
+	if (!ret) {
+		ret = kxcjk1013_set_power_state(data, state);
+		if (ret < 0) {
 			mutex_unlock(&data->mutex);
-			return 0;
+			return ret;
 		}
-		kxcjk1013_chip_setup_interrupt(data, false);
-		kxcjk1013_set_mode(data, STANDBY);
 	}
+	data->trigger_on = state;
 	mutex_unlock(&data->mutex);
 
 	return 0;
@@ -660,14 +736,22 @@ static int kxcjk1013_probe(struct i2c_client *client,
 		}
 	}
 
-	ret = devm_iio_device_register(&client->dev, indio_dev);
+	ret = iio_device_register(indio_dev);
 	if (ret < 0) {
 		dev_err(&client->dev, "unable to register iio device\n");
 		goto err_buffer_cleanup;
 	}
 
+	ret = pm_runtime_set_active(&client->dev);
+	if (ret)
+		goto err_iio_unregister;
+
+	pm_runtime_enable(&client->dev);
+
 	return 0;
 
+err_iio_unregister:
+	iio_device_unregister(indio_dev);
 err_buffer_cleanup:
 	if (data->trig_mode)
 		iio_triggered_buffer_cleanup(indio_dev);
@@ -686,6 +770,12 @@ static int kxcjk1013_remove(struct i2c_client *client)
 	struct iio_dev *indio_dev = i2c_get_clientdata(client);
 	struct kxcjk1013_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);
+
 	if (data->trig_mode) {
 		iio_triggered_buffer_cleanup(indio_dev);
 		iio_trigger_unregister(data->trig);
@@ -704,35 +794,67 @@ static int kxcjk1013_suspend(struct device *dev)
 {
 	struct iio_dev *indio_dev = i2c_get_clientdata(to_i2c_client(dev));
 	struct kxcjk1013_data *data = iio_priv(indio_dev);
+	int ret;
 
 	mutex_lock(&data->mutex);
-	kxcjk1013_set_mode(data, STANDBY);
+	ret = kxcjk1013_set_mode(data, STANDBY);
 	mutex_unlock(&data->mutex);
 
-	return 0;
+	return ret;
 }
 
 static int kxcjk1013_resume(struct device *dev)
 {
 	struct iio_dev *indio_dev = i2c_get_clientdata(to_i2c_client(dev));
 	struct kxcjk1013_data *data = iio_priv(indio_dev);
+	int ret = 0;
 
 	mutex_lock(&data->mutex);
+	/* Check, if the suspend occured while active */
+	if (data->trigger_on)
+		ret = kxcjk1013_set_mode(data, OPERATION);
+	mutex_unlock(&data->mutex);
 
-	if (data->power_state)
-		kxcjk1013_set_mode(data, OPERATION);
+	return ret;
+}
+#endif
 
-	mutex_unlock(&data->mutex);
+#ifdef CONFIG_PM_RUNTIME
+static int kxcjk1013_runtime_suspend(struct device *dev)
+{
+	struct iio_dev *indio_dev = i2c_get_clientdata(to_i2c_client(dev));
+	struct kxcjk1013_data *data = iio_priv(indio_dev);
 
-	return 0;
+	return kxcjk1013_set_mode(data, STANDBY);
 }
 
-static SIMPLE_DEV_PM_OPS(kxcjk1013_pm_ops, kxcjk1013_suspend, kxcjk1013_resume);
-#define KXCJK1013_PM_OPS (&kxcjk1013_pm_ops)
-#else
-#define KXCJK1013_PM_OPS NULL
+static int kxcjk1013_runtime_resume(struct device *dev)
+{
+	struct iio_dev *indio_dev = i2c_get_clientdata(to_i2c_client(dev));
+	struct kxcjk1013_data *data = iio_priv(indio_dev);
+	int ret;
+	int sleep_val;
+
+	ret = kxcjk1013_set_mode(data, OPERATION);
+	if (ret < 0)
+		return ret;
+
+	sleep_val = kxcjk1013_get_startup_times(data);
+	if (sleep_val < 20000)
+		usleep_range(sleep_val, 20000);
+	else
+		msleep_interruptible(sleep_val/1000);
+
+	return 0;
+}
 #endif
 
+static const struct dev_pm_ops kxcjk1013_pm_ops = {
+	SET_SYSTEM_SLEEP_PM_OPS(kxcjk1013_suspend, kxcjk1013_resume)
+	SET_RUNTIME_PM_OPS(kxcjk1013_runtime_suspend,
+			   kxcjk1013_runtime_resume, NULL)
+};
+
 static const struct acpi_device_id kx_acpi_match[] = {
 	{"KXCJ1013", 0},
 	{ },
@@ -750,7 +872,7 @@ static struct i2c_driver kxcjk1013_driver = {
 	.driver = {
 		.name	= KXCJK1013_DRV_NAME,
 		.acpi_match_table = ACPI_PTR(kx_acpi_match),
-		.pm	= KXCJK1013_PM_OPS,
+		.pm	= &kxcjk1013_pm_ops,
 	},
 	.probe		= kxcjk1013_probe,
 	.remove		= kxcjk1013_remove,
-- 
1.7.11.7