power: supply: charger-manager: Make decisions focussed on battery status

cm_monitor(), where charging management starts, checks various charging
condition sequentially to decide next charging operation. However, as it
follows sequential process, cascaded if statements, it does some
jobs which have already done in the previous stage. This results in a
delay in decision making. Moreover, starting point of charging is spread
all around which makes maintain code and debugging difficult.

Both of the problems mentioned above become clean if it manages battery
charging focusing on battery status not following sequential condition
checking.  Now, cm_monitor() moves battery state diagram and does the
optimal operation for current state. As a result, it reduces whole
monitoring time almost in half.
Signed-off-by: Jonghwa Lee <jonghwa3.lee@samsung.com>
Signed-off-by: Krzysztof Kozlowski <k.kozlowski@samsung.com>
Signed-off-by: Jonathan Bakker <xc-racer2@live.ca>
Signed-off-by: Sebastian Reichel <sebastian.reichel@collabora.com>

drivers/power/supply/charger-manager.c

@@ -271,6 +271,19 @@ static bool is_full_charged(struct charger_manager *cm)
 	if (!fuel_gauge)
 		return false;
 
+	/* Full, if it's over the fullbatt voltage */
+	if (desc->fullbatt_uV > 0) {
+		ret = get_batt_uV(cm, &uV);
+		if (!ret) {
+			/* Battery is already full, checks voltage drop. */
+			if (cm->battery_status == POWER_SUPPLY_STATUS_FULL
+					&& desc->fullbatt_vchkdrop_uV)
+				uV += desc->fullbatt_vchkdrop_uV;
+			if (uV >= desc->fullbatt_uV)
+				return true;
+		}
+	}
+
 	if (desc->fullbatt_full_capacity > 0) {
 		val.intval = 0;
 
@@ -283,15 +296,6 @@ static bool is_full_charged(struct charger_manager *cm)
 		}
 	}
 
-	/* Full, if it's over the fullbatt voltage */
-	if (desc->fullbatt_uV > 0) {
-		ret = get_batt_uV(cm, &uV);
-		if (!ret && uV >= desc->fullbatt_uV) {
-			is_full = true;
-			goto out;
-		}
-	}
-
 	/* Full, if the capacity is more than fullbatt_soc */
 	if (desc->fullbatt_soc > 0) {
 		val.intval = 0;
@@ -406,66 +410,12 @@ static int try_charger_enable(struct charger_manager *cm, bool enable)
 		}
 	}
 
-	if (!err) {
+	if (!err)
 		cm->charger_enabled = enable;
-		power_supply_changed(cm->charger_psy);
-	}
 
 	return err;
 }
 
-/**
- * try_charger_restart - Restart charging.
- * @cm: the Charger Manager representing the battery.
- *
- * Restart charging by turning off and on the charger.
- */
-static int try_charger_restart(struct charger_manager *cm)
-{
-	int err;
-
-	if (cm->emergency_stop)
-		return -EAGAIN;
-
-	err = try_charger_enable(cm, false);
-	if (err)
-		return err;
-
-	return try_charger_enable(cm, true);
-}
-
-/**
- * fullbatt_vchk - Check voltage drop some times after "FULL" event.
- *
- * If a user has designated "fullbatt_vchkdrop_uV" values with
- * charger_desc, Charger Manager checks voltage drop after the battery
- * "FULL" event. It checks whether the voltage has dropped more than
- * fullbatt_vchkdrop_uV by calling this function after fullbatt_vchkrop_ms.
- */
-static void fullbatt_vchk(struct charger_manager *cm)
-{
-	struct charger_desc *desc = cm->desc;
-	int batt_uV, err, diff;
-
-	if (!desc->fullbatt_vchkdrop_uV)
-		return;
-
-	err = get_batt_uV(cm, &batt_uV);
-	if (err) {
-		dev_err(cm->dev, "%s: get_batt_uV error(%d)\n", __func__, err);
-		return;
-	}
-
-	diff = desc->fullbatt_uV - batt_uV;
-	if (diff < 0)
-		return;
-
-	dev_info(cm->dev, "VBATT dropped %duV after full-batt\n", diff);
-
-	if (diff > desc->fullbatt_vchkdrop_uV)
-		try_charger_restart(cm);
-}
-
 /**
  * check_charging_duration - Monitor charging/discharging duration
  * @cm: the Charger Manager representing the battery.
@@ -493,17 +443,14 @@ static int check_charging_duration(struct charger_manager *cm)
 		if (duration > desc->charging_max_duration_ms) {
 			dev_info(cm->dev, "Charging duration exceed %ums\n",
 				 desc->charging_max_duration_ms);
-			try_charger_enable(cm, false);
 			ret = true;
 		}
-	} else if (is_ext_pwr_online(cm) && !cm->charger_enabled) {
+	} else if (cm->battery_status == POWER_SUPPLY_STATUS_NOT_CHARGING) {
 		duration = curr - cm->charging_end_time;
 
-		if (duration > desc->discharging_max_duration_ms &&
-				is_ext_pwr_online(cm)) {
+		if (duration > desc->charging_max_duration_ms) {
 			dev_info(cm->dev, "Discharging duration exceed %ums\n",
 				 desc->discharging_max_duration_ms);
-			try_charger_enable(cm, true);
 			ret = true;
 		}
 	}
@@ -585,9 +532,46 @@ static int cm_check_thermal_status(struct charger_manager *cm)
 	else
 		ret = CM_BATT_OK;
 
+	cm->emergency_stop = ret;
+
 	return ret;
 }
 
+/**
+ * cm_get_target_status - Check current status and get next target status.
+ * @cm: the Charger Manager representing the battery.
+ */
+static int cm_get_target_status(struct charger_manager *cm)
+{
+	if (!is_ext_pwr_online(cm))
+		return POWER_SUPPLY_STATUS_DISCHARGING;
+
+	if (cm_check_thermal_status(cm)) {
+		/* Check if discharging duration exeeds limit. */
+		if (check_charging_duration(cm))
+			goto charging_ok;
+		return POWER_SUPPLY_STATUS_NOT_CHARGING;
+	}
+
+	switch (cm->battery_status) {
+	case POWER_SUPPLY_STATUS_CHARGING:
+		/* Check if charging duration exeeds limit. */
+		if (check_charging_duration(cm))
+			return POWER_SUPPLY_STATUS_FULL;
+		fallthrough;
+	case POWER_SUPPLY_STATUS_FULL:
+		if (is_full_charged(cm))
+			return POWER_SUPPLY_STATUS_FULL;
+		fallthrough;
+	default:
+		break;
+	}
+
+charging_ok:
+	/* Charging is allowed. */
+	return POWER_SUPPLY_STATUS_CHARGING;
+}
+
 /**
  * _cm_monitor - Monitor the temperature and return true for exceptions.
  * @cm: the Charger Manager representing the battery.
@@ -597,56 +581,18 @@ static int cm_check_thermal_status(struct charger_manager *cm)
  */
 static bool _cm_monitor(struct charger_manager *cm)
 {
-	int temp_alrt;
+	int target;
 
-	temp_alrt = cm_check_thermal_status(cm);
+	target = cm_get_target_status(cm);
 
-	/* It has been stopped already */
-	if (temp_alrt && cm->emergency_stop)
-		return false;
-
-	/*
-	 * Check temperature whether overheat or cold.
-	 * If temperature is out of range normal state, stop charging.
-	 */
-	if (temp_alrt) {
-		cm->emergency_stop = temp_alrt;
-		try_charger_enable(cm, false);
-
-	/*
-	 * Check whole charging duration and discharging duration
-	 * after full-batt.
-	 */
-	} else if (!cm->emergency_stop && check_charging_duration(cm)) {
-		dev_dbg(cm->dev,
-			"Charging/Discharging duration is out of range\n");
-	/*
-	 * Check dropped voltage of battery. If battery voltage is more
-	 * dropped than fullbatt_vchkdrop_uV after fully charged state,
-	 * charger-manager have to recharge battery.
-	 */
-	} else if (!cm->emergency_stop && is_ext_pwr_online(cm) &&
-			!cm->charger_enabled) {
-		fullbatt_vchk(cm);
+	try_charger_enable(cm, (target == POWER_SUPPLY_STATUS_CHARGING));
 
-	/*
-	 * Check whether fully charged state to protect overcharge
-	 * if charger-manager is charging for battery.
-	 */
-	} else if (!cm->emergency_stop && is_full_charged(cm) &&
-			cm->charger_enabled) {
-		dev_info(cm->dev, "EVENT_HANDLE: Battery Fully Charged\n");
-		try_charger_enable(cm, false);
-
-		fullbatt_vchk(cm);
-	} else {
-		cm->emergency_stop = 0;
-		if (is_ext_pwr_online(cm)) {
-			try_charger_enable(cm, true);
-		}
+	if (cm->battery_status != target) {
+		cm->battery_status = target;
+		power_supply_changed(cm->charger_psy);
 	}
 
-	return true;
+	return (cm->battery_status == POWER_SUPPLY_STATUS_NOT_CHARGING);
 }
 
 /**
@@ -751,12 +697,7 @@ static int charger_get_property(struct power_supply *psy,
 
 	switch (psp) {
 	case POWER_SUPPLY_PROP_STATUS:
-		if (is_charging(cm))
-			val->intval = POWER_SUPPLY_STATUS_CHARGING;
-		else if (is_ext_pwr_online(cm))
-			val->intval = POWER_SUPPLY_STATUS_NOT_CHARGING;
-		else
-			val->intval = POWER_SUPPLY_STATUS_DISCHARGING;
+		val->intval = cm->battery_status;
 		break;
 	case POWER_SUPPLY_PROP_HEALTH:
 		if (cm->emergency_stop > 0)

include/linux/power/charger-manager.h

@@ -213,6 +213,7 @@ struct charger_desc {
  *	saved status of battery before entering suspend-to-RAM
  * @charging_start_time: saved start time of enabling charging
  * @charging_end_time: saved end time of disabling charging
+ * @battery_status: Current battery status
  */
 struct charger_manager {
 	struct list_head entry;
@@ -232,6 +233,8 @@ struct charger_manager {
 
 	u64 charging_start_time;
 	u64 charging_end_time;
+
+	int battery_status;
 };
 
 #endif /* _CHARGER_MANAGER_H */