hwmon: (ina3221) Implement PM runtime to save power

index 975c95169884..14cfab64649f 100644
@@ -625,7 +625,12 @@ __hwmon_device_register(struct device *dev, const char *name, void *drvdata,
 	hwdev->name = name;
 	hdev->class = &hwmon_class;
 	hdev->parent = dev;
-	hdev->of_node = dev ? dev->of_node : NULL;
+	if (dev) {
+		hdev->driver = dev->driver;
+		hdev->power = dev->power;
+		hdev->pm_domain = dev->pm_domain;
+		hdev->of_node = dev->of_node;
+	}
 	hwdev->chip = chip;
 	dev_set_drvdata(hdev, drvdata);
 	dev_set_name(hdev, HWMON_ID_FORMAT, id);

index d61688f04594..26cdf3342d80 100644
@@ -200,6 +200,12 @@ static int ina3221_read_curr(struct device *dev, u32 attr,
 		return 0;
 	case hwmon_curr_crit_alarm:
 	case hwmon_curr_max_alarm:
+		/* No actual register read if channel is disabled */
+		if (!ina3221_is_enabled(ina, channel)) {
+			/* Return 0 for alert flags */
+			*val = 0;
+			return 0;
+		}
 		ret = regmap_field_read(ina->fields[reg], &regval);
 		if (ret)
 			return ret;

index 26cdf3342d80..10e8347a3c80 100644
@@ -18,6 +18,7 @@
 #include <linux/hwmon-sysfs.h>
 #include <linux/i2c.h>
 #include <linux/module.h>
+#include <linux/mutex.h>
 #include <linux/of.h>
 #include <linux/regmap.h>
 

@@ -94,12 +95,14 @@ struct ina3221_input {
  * @regmap: Register map of the device
  * @fields: Register fields of the device
  * @inputs: Array of channel input source specific structures
+ * @lock: mutex lock to serialize sysfs attribute accesses
  * @reg_config: Register value of INA3221_CONFIG
  */
 struct ina3221_data {
 	struct regmap *regmap;
 	struct regmap_field *fields[F_MAX_FIELDS];
 	struct ina3221_input inputs[INA3221_NUM_CHANNELS];
+	struct mutex lock;
 	u32 reg_config;
 };
 

@@ -265,29 +268,53 @@ static int ina3221_write_enable(struct device *dev, int channel, bool enable)
 static int ina3221_read(struct device *dev, enum hwmon_sensor_types type,
 			u32 attr, int channel, long *val)
 {
+	struct ina3221_data *ina = dev_get_drvdata(dev);
+	int ret;
+
+	mutex_lock(&ina->lock);
+
 	switch (type) {
 	case hwmon_in:
 		/* 0-align channel ID */
-		return ina3221_read_in(dev, attr, channel - 1, val);
+		ret = ina3221_read_in(dev, attr, channel - 1, val);
+		break;
 	case hwmon_curr:
-		return ina3221_read_curr(dev, attr, channel, val);
+		ret = ina3221_read_curr(dev, attr, channel, val);
+		break;
 	default:
-		return -EOPNOTSUPP;
+		ret = -EOPNOTSUPP;
+		break;
 	}
+
+	mutex_unlock(&ina->lock);
+
+	return ret;
 }
 
 static int ina3221_write(struct device *dev, enum hwmon_sensor_types type,
 			 u32 attr, int channel, long val)
 {
+	struct ina3221_data *ina = dev_get_drvdata(dev);
+	int ret;
+
+	mutex_lock(&ina->lock);
+
 	switch (type) {
 	case hwmon_in:
 		/* 0-align channel ID */
-		return ina3221_write_enable(dev, channel - 1, val);
+		ret = ina3221_write_enable(dev, channel - 1, val);
+		break;
 	case hwmon_curr:
-		return ina3221_write_curr(dev, attr, channel, val);
+		ret = ina3221_write_curr(dev, attr, channel, val);
+		break;
 	default:
-		return -EOPNOTSUPP;
+		ret = -EOPNOTSUPP;
+		break;
 	}
+
+	mutex_unlock(&ina->lock);
+
+	return ret;
 }
 
 static int ina3221_read_string(struct device *dev, enum hwmon_sensor_types type,

@@ -582,6 +609,7 @@ static int ina3221_probe(struct i2c_client *client,
 	if (ret)
 		return ret;
 
+	mutex_init(&ina->lock);
 	dev_set_drvdata(dev, ina);
 
 	hwmon_dev = devm_hwmon_device_register_with_info(dev, client->name, ina,

@@ -589,12 +617,22 @@ static int ina3221_probe(struct i2c_client *client,
 							 ina3221_groups);
 	if (IS_ERR(hwmon_dev)) {
 		dev_err(dev, "Unable to register hwmon device\n");
+		mutex_destroy(&ina->lock);
 		return PTR_ERR(hwmon_dev);
 	}
 
 	return 0;
 }
 
+static int ina3221_remove(struct i2c_client *client)
+{
+	struct ina3221_data *ina = dev_get_drvdata(&client->dev);
+
+	mutex_destroy(&ina->lock);
+
+	return 0;
+}
+
 static int __maybe_unused ina3221_suspend(struct device *dev)
 {
 	struct ina3221_data *ina = dev_get_drvdata(dev);

@@ -663,6 +701,7 @@ MODULE_DEVICE_TABLE(i2c, ina3221_ids);
 
 static struct i2c_driver ina3221_i2c_driver = {
 	.probe = ina3221_probe,
+	.remove = ina3221_remove,
 	.driver = {
 		.name = INA3221_DRIVER_NAME,
 		.of_match_table = ina3221_of_match_table,

index 10e8347a3c80..07dd6ef58d3e 100644
@@ -44,6 +44,13 @@
 #define INA3221_CONFIG_MODE_SHUNT	BIT(0)
 #define INA3221_CONFIG_MODE_BUS		BIT(1)
 #define INA3221_CONFIG_MODE_CONTINUOUS	BIT(2)
+#define INA3221_CONFIG_VSH_CT_SHIFT	3
+#define INA3221_CONFIG_VSH_CT_MASK	GENMASK(5, 3)
+#define INA3221_CONFIG_VSH_CT(x)	(((x) & GENMASK(5, 3)) >> 3)
+#define INA3221_CONFIG_VBUS_CT_SHIFT	6
+#define INA3221_CONFIG_VBUS_CT_MASK	GENMASK(8, 6)
+#define INA3221_CONFIG_VBUS_CT(x)	(((x) & GENMASK(8, 6)) >> 6)
+#define INA3221_CONFIG_CHs_EN_MASK	GENMASK(14, 12)
 #define INA3221_CONFIG_CHx_EN(x)	BIT(14 - (x))
 
 #define INA3221_RSHUNT_DEFAULT		10000

@@ -52,6 +59,9 @@ enum ina3221_fields {
 	/* Configuration */
 	F_RST,
 
+	/* Status Flags */
+	F_CVRF,
+
 	/* Alert Flags */
 	F_WF3, F_WF2, F_WF1,
 	F_CF3, F_CF2, F_CF1,

@@ -63,6 +73,7 @@ enum ina3221_fields {
 static const struct reg_field ina3221_reg_fields[] = {
 	[F_RST] = REG_FIELD(INA3221_CONFIG, 15, 15),
 
+	[F_CVRF] = REG_FIELD(INA3221_MASK_ENABLE, 0, 0),
 	[F_WF3] = REG_FIELD(INA3221_MASK_ENABLE, 3, 3),
 	[F_WF2] = REG_FIELD(INA3221_MASK_ENABLE, 4, 4),
 	[F_WF1] = REG_FIELD(INA3221_MASK_ENABLE, 5, 5),

@@ -111,6 +122,28 @@ static inline bool ina3221_is_enabled(struct ina3221_data *ina, int channel)
 	return ina->reg_config & INA3221_CONFIG_CHx_EN(channel);
 }
 
+/* Lookup table for Bus and Shunt conversion times in usec */
+static const u16 ina3221_conv_time[] = {
+	140, 204, 332, 588, 1100, 2116, 4156, 8244,
+};
+
+static inline int ina3221_wait_for_data(struct ina3221_data *ina)
+{
+	u32 channels = hweight16(ina->reg_config & INA3221_CONFIG_CHs_EN_MASK);
+	u32 vbus_ct_idx = INA3221_CONFIG_VBUS_CT(ina->reg_config);
+	u32 vsh_ct_idx = INA3221_CONFIG_VSH_CT(ina->reg_config);
+	u32 vbus_ct = ina3221_conv_time[vbus_ct_idx];
+	u32 vsh_ct = ina3221_conv_time[vsh_ct_idx];
+	u32 wait, cvrf;
+
+	/* Calculate total conversion time */
+	wait = channels * (vbus_ct + vsh_ct);
+
+	/* Polling the CVRF bit to make sure read data is ready */
+	return regmap_field_read_poll_timeout(ina->fields[F_CVRF],
+					      cvrf, cvrf, wait, 100000);
+}
+
 static int ina3221_read_value(struct ina3221_data *ina, unsigned int reg,
 			      int *val)
 {

@@ -150,6 +183,10 @@ static int ina3221_read_in(struct device *dev, u32 attr, int channel, long *val)
 		if (!ina3221_is_enabled(ina, channel))
 			return -ENODATA;
 
+		ret = ina3221_wait_for_data(ina);
+		if (ret)
+			return ret;
+
 		ret = ina3221_read_value(ina, reg, &regval);
 		if (ret)
 			return ret;

@@ -189,6 +226,11 @@ static int ina3221_read_curr(struct device *dev, u32 attr,
 	case hwmon_curr_input:
 		if (!ina3221_is_enabled(ina, channel))
 			return -ENODATA;
+
+		ret = ina3221_wait_for_data(ina);
+		if (ret)
+			return ret;
+
 		/* fall through */
 	case hwmon_curr_crit:
 	case hwmon_curr_max:

index 07dd6ef58d3e..3e7c6fac6e1b 100644
@@ -20,6 +20,7 @@
 #include <linux/module.h>
 #include <linux/mutex.h>
 #include <linux/of.h>
+#include <linux/pm_runtime.h>
 #include <linux/regmap.h>
 
 #define INA3221_DRIVER_NAME		"ina3221"

@@ -53,6 +54,7 @@
 #define INA3221_CONFIG_CHs_EN_MASK	GENMASK(14, 12)
 #define INA3221_CONFIG_CHx_EN(x)	BIT(14 - (x))
 
+#define INA3221_CONFIG_DEFAULT		0x7127
 #define INA3221_RSHUNT_DEFAULT		10000
 
 enum ina3221_fields {

@@ -103,6 +105,7 @@ struct ina3221_input {
 
 /**
  * struct ina3221_data - device specific information
+ * @hdev: Device pointer of hwmon child device, used for pm runtime
  * @regmap: Register map of the device
  * @fields: Register fields of the device
  * @inputs: Array of channel input source specific structures

@@ -110,6 +113,7 @@ struct ina3221_input {
  * @reg_config: Register value of INA3221_CONFIG
  */
 struct ina3221_data {
+	struct device *hdev;
 	struct regmap *regmap;
 	struct regmap_field *fields[F_MAX_FIELDS];
 	struct ina3221_input inputs[INA3221_NUM_CHANNELS];

@@ -119,7 +123,8 @@ struct ina3221_data {
 
 static inline bool ina3221_is_enabled(struct ina3221_data *ina, int channel)
 {
-	return ina->reg_config & INA3221_CONFIG_CHx_EN(channel);
+	return pm_runtime_active(ina->hdev) &&
+	       (ina->reg_config & INA3221_CONFIG_CHx_EN(channel));
 }
 
 /* Lookup table for Bus and Shunt conversion times in usec */

@@ -290,21 +295,48 @@ static int ina3221_write_enable(struct device *dev, int channel, bool enable)
 {
 	struct ina3221_data *ina = dev_get_drvdata(dev);
 	u16 config, mask = INA3221_CONFIG_CHx_EN(channel);
+	u16 config_old = ina->reg_config & mask;
 	int ret;
 
 	config = enable ? mask : 0;
 
+	/* Bypass if enable status is not being changed */
+	if (config_old == config)
+		return 0;
+
+	/* For enabling routine, increase refcount and resume() at first */
+	if (enable) {
+		ret = pm_runtime_get_sync(ina->hdev);
+		if (ret < 0) {
+			dev_err(dev, "Failed to get PM runtime\n");
+			return ret;
+		}
+	}
+
 	/* Enable or disable the channel */
 	ret = regmap_update_bits(ina->regmap, INA3221_CONFIG, mask, config);
 	if (ret)
-		return ret;
+		goto fail;
 
 	/* Cache the latest config register value */
 	ret = regmap_read(ina->regmap, INA3221_CONFIG, &ina->reg_config);
 	if (ret)
-		return ret;
+		goto fail;
+
+	/* For disabling routine, decrease refcount or suspend() at last */
+	if (!enable)
+		pm_runtime_put_sync(ina->hdev);
 
 	return 0;
+
+fail:
+	if (enable) {
+		dev_err(dev, "Failed to enable channel %d: error %d\n",
+			channel, ret);
+		pm_runtime_put_sync(ina->hdev);
+	}
+
+	return ret;
 }
 
 static int ina3221_read(struct device *dev, enum hwmon_sensor_types type,

@@ -599,7 +631,6 @@ static int ina3221_probe(struct i2c_client *client,
 {
 	struct device *dev = &client->dev;
 	struct ina3221_data *ina;
-	struct device *hwmon_dev;
 	int i, ret;
 
 	ina = devm_kzalloc(dev, sizeof(*ina), GFP_KERNEL);

@@ -631,44 +662,72 @@ static int ina3221_probe(struct i2c_client *client,
 		return ret;
 	}
 
-	ret = regmap_field_write(ina->fields[F_RST], true);
-	if (ret) {
-		dev_err(dev, "Unable to reset device\n");
-		return ret;
-	}
-
-	/* Sync config register after reset */
-	ret = regmap_read(ina->regmap, INA3221_CONFIG, &ina->reg_config);
-	if (ret)
-		return ret;
+	/* The driver will be reset, so use reset value */
+	ina->reg_config = INA3221_CONFIG_DEFAULT;
 
 	/* Disable channels if their inputs are disconnected */
 	for (i = 0; i < INA3221_NUM_CHANNELS; i++) {
 		if (ina->inputs[i].disconnected)
 			ina->reg_config &= ~INA3221_CONFIG_CHx_EN(i);
 	}
-	ret = regmap_write(ina->regmap, INA3221_CONFIG, ina->reg_config);
-	if (ret)
-		return ret;
 
 	mutex_init(&ina->lock);
 	dev_set_drvdata(dev, ina);
 
-	hwmon_dev = devm_hwmon_device_register_with_info(dev, client->name, ina,
+	/* Fence sysfs nodes till pm_runtime is resumed */
+	mutex_lock(&ina->lock);
+
+	/* Use the returned hdev for pm_runtime */
+	ina->hdev = devm_hwmon_device_register_with_info(dev, client->name, ina,
 							 &ina3221_chip_info,
 							 ina3221_groups);
-	if (IS_ERR(hwmon_dev)) {
+	if (IS_ERR(ina->hdev)) {
 		dev_err(dev, "Unable to register hwmon device\n");
-		mutex_destroy(&ina->lock);
-		return PTR_ERR(hwmon_dev);
+		ret = PTR_ERR(ina->hdev);
+		goto fail_lock;
 	}
 
+	/* Enable PM runtime -- status is suspended by default */
+	pm_runtime_enable(ina->hdev);
+
+	/* Initialize (resume) the device */
+	for (i = 0; i < INA3221_NUM_CHANNELS; i++) {
+		if (ina->inputs[i].disconnected)
+			continue;
+		/* Match the refcount with number of enabled channels */
+		ret = pm_runtime_get_sync(ina->hdev);
+		if (ret < 0)
+			goto fail_pm;
+	}
+
+	mutex_unlock(&ina->lock);
+
 	return 0;
+
+fail_pm:
+	pm_runtime_disable(ina->hdev);
+	pm_runtime_set_suspended(ina->hdev);
+	/* pm_runtime_put_noidle() will decrease the PM refcount until 0 */
+	for (i = 0; i < INA3221_NUM_CHANNELS; i++)
+		pm_runtime_put_noidle(ina->hdev);
+fail_lock:
+	mutex_unlock(&ina->lock);
+	mutex_destroy(&ina->lock);
+
+	return ret;
 }
 
 static int ina3221_remove(struct i2c_client *client)
 {
 	struct ina3221_data *ina = dev_get_drvdata(&client->dev);
+	int i;
+
+	pm_runtime_disable(ina->hdev);
+	pm_runtime_set_suspended(ina->hdev);
+
+	/* pm_runtime_put_noidle() will decrease the PM refcount until 0 */
+	for (i = 0; i < INA3221_NUM_CHANNELS; i++)
+		pm_runtime_put_noidle(ina->hdev);
 
 	mutex_destroy(&ina->lock);
 

@@ -680,6 +739,10 @@ static int __maybe_unused ina3221_suspend(struct device *dev)
 	struct ina3221_data *ina = dev_get_drvdata(dev);
 	int ret;
 
+	/* Let hdev control all PM runtime callbacks */
+	if (dev != ina->hdev)
+		return 0;
+
 	/* Save config register value and enable cache-only */
 	ret = regmap_read(ina->regmap, INA3221_CONFIG, &ina->reg_config);
 	if (ret)

@@ -703,6 +766,10 @@ static int __maybe_unused ina3221_resume(struct device *dev)
 	struct ina3221_data *ina = dev_get_drvdata(dev);
 	int ret;
 
+	/* Let hdev control all PM runtime callbacks */
+	if (dev != ina->hdev)
+		return 0;
+
 	regcache_cache_only(ina->regmap, false);
 
 	/* Software reset the chip */

@@ -726,7 +793,9 @@ static int __maybe_unused ina3221_resume(struct device *dev)
 }
 
 static const struct dev_pm_ops ina3221_pm = {
-	SET_SYSTEM_SLEEP_PM_OPS(ina3221_suspend, ina3221_resume)
+	SET_SYSTEM_SLEEP_PM_OPS(pm_runtime_force_suspend,
+				pm_runtime_force_resume)
+	SET_RUNTIME_PM_OPS(ina3221_suspend, ina3221_resume, NULL)
 };
 
 static const struct of_device_id ina3221_of_match_table[] = {