smb347-charger: Fix battery status reporting logic for charger faults

This patch checks for charger status register for determining the
battery charging status and reports Discharing/Charging/Not Charging/Full
accordingly.

This patch also adds the interrupt support for Safety Timer Expiration.
This interrupt is helpful in debugging the cause for charger fault.

Signed-off-by: Ramakrishna Pallala <ramakrishna.pallala@intel.com>
Acked-by: Mika Westerberg <mika.westerberg@linux.intel.com>
Signed-off-by: Anton Vorontsov <anton.vorontsov@linaro.org>

drivers/power/smb347-charger.c

@@ -80,6 +80,7 @@
 #define CFG_FAULT_IRQ_DCIN_UV			BIT(2)
 #define CFG_STATUS_IRQ				0x0d
 #define CFG_STATUS_IRQ_TERMINATION_OR_TAPER	BIT(4)
+#define CFG_STATUS_IRQ_CHARGE_TIMEOUT		BIT(7)
 #define CFG_ADDRESS				0x0e
 
 /* Command registers */
@@ -96,6 +97,9 @@
 #define IRQSTAT_C_TERMINATION_STAT		BIT(0)
 #define IRQSTAT_C_TERMINATION_IRQ		BIT(1)
 #define IRQSTAT_C_TAPER_IRQ			BIT(3)
+#define IRQSTAT_D				0x38
+#define IRQSTAT_D_CHARGE_TIMEOUT_STAT		BIT(2)
+#define IRQSTAT_D_CHARGE_TIMEOUT_IRQ		BIT(3)
 #define IRQSTAT_E				0x39
 #define IRQSTAT_E_USBIN_UV_STAT			BIT(0)
 #define IRQSTAT_E_USBIN_UV_IRQ			BIT(1)
@@ -109,8 +113,10 @@
 #define STAT_B					0x3c
 #define STAT_C					0x3d
 #define STAT_C_CHG_ENABLED			BIT(0)
+#define STAT_C_HOLDOFF_STAT			BIT(3)
 #define STAT_C_CHG_MASK				0x06
 #define STAT_C_CHG_SHIFT			1
+#define STAT_C_CHG_TERM				BIT(5)
 #define STAT_C_CHARGER_ERROR			BIT(6)
 #define STAT_E					0x3f
 
@@ -701,7 +707,7 @@ fail:
 static irqreturn_t smb347_interrupt(int irq, void *data)
 {
 	struct smb347_charger *smb = data;
-	unsigned int stat_c, irqstat_e, irqstat_c;
+	unsigned int stat_c, irqstat_c, irqstat_d, irqstat_e;
 	bool handled = false;
 	int ret;
 
@@ -717,6 +723,12 @@ static irqreturn_t smb347_interrupt(int irq, void *data)
 		return IRQ_NONE;
 	}
 
+	ret = regmap_read(smb->regmap, IRQSTAT_D, &irqstat_d);
+	if (ret < 0) {
+		dev_warn(smb->dev, "reading IRQSTAT_D failed\n");
+		return IRQ_NONE;
+	}
+
 	ret = regmap_read(smb->regmap, IRQSTAT_E, &irqstat_e);
 	if (ret < 0) {
 		dev_warn(smb->dev, "reading IRQSTAT_E failed\n");
@@ -724,13 +736,11 @@ static irqreturn_t smb347_interrupt(int irq, void *data)
 	}
 
 	/*
-	 * If we get charger error we report the error back to user and
-	 * disable charging.
+	 * If we get charger error we report the error back to user.
+	 * If the error is recovered charging will resume again.
 	 */
 	if (stat_c & STAT_C_CHARGER_ERROR) {
-		dev_err(smb->dev, "error in charger, disabling charging\n");
-
-		smb347_charging_disable(smb);
+		dev_err(smb->dev, "charging stopped due to charger error\n");
 		power_supply_changed(&smb->battery);
 		handled = true;
 	}
@@ -743,6 +753,20 @@ static irqreturn_t smb347_interrupt(int irq, void *data)
 	if (irqstat_c & (IRQSTAT_C_TERMINATION_IRQ | IRQSTAT_C_TAPER_IRQ)) {
 		if (irqstat_c & IRQSTAT_C_TERMINATION_STAT)
 			power_supply_changed(&smb->battery);
+		dev_dbg(smb->dev, "going to HW maintenance mode\n");
+		handled = true;
+	}
+
+	/*
+	 * If we got a charger timeout INT that means the charge
+	 * full is not detected with in charge timeout value.
+	 */
+	if (irqstat_d & IRQSTAT_D_CHARGE_TIMEOUT_IRQ) {
+		dev_dbg(smb->dev, "total Charge Timeout INT received\n");
+
+		if (irqstat_d & IRQSTAT_D_CHARGE_TIMEOUT_STAT)
+			dev_warn(smb->dev, "charging stopped due to timeout\n");
+		power_supply_changed(&smb->battery);
 		handled = true;
 	}
 
@@ -776,6 +800,7 @@ static int smb347_irq_set(struct smb347_charger *smb, bool enable)
 	 * Enable/disable interrupts for:
 	 *	- under voltage
 	 *	- termination current reached
+	 *	- charger timeout
 	 *	- charger error
 	 */
 	ret = regmap_update_bits(smb->regmap, CFG_FAULT_IRQ, 0xff,
@@ -784,7 +809,8 @@ static int smb347_irq_set(struct smb347_charger *smb, bool enable)
 		goto fail;
 
 	ret = regmap_update_bits(smb->regmap, CFG_STATUS_IRQ, 0xff,
-			enable ? CFG_STATUS_IRQ_TERMINATION_OR_TAPER : 0);
+			enable ? (CFG_STATUS_IRQ_TERMINATION_OR_TAPER |
+					CFG_STATUS_IRQ_CHARGE_TIMEOUT) : 0);
 	if (ret < 0)
 		goto fail;
 
@@ -988,6 +1014,51 @@ static enum power_supply_property smb347_usb_properties[] = {
 	POWER_SUPPLY_PROP_CONSTANT_CHARGE_VOLTAGE,
 };
 
+static int smb347_get_charging_status(struct smb347_charger *smb)
+{
+	int ret, status;
+	unsigned int val;
+
+	if (!smb347_is_ps_online(smb))
+		return POWER_SUPPLY_STATUS_DISCHARGING;
+
+	ret = regmap_read(smb->regmap, STAT_C, &val);
+	if (ret < 0)
+		return ret;
+
+	if ((val & STAT_C_CHARGER_ERROR) ||
+			(val & STAT_C_HOLDOFF_STAT)) {
+		/*
+		 * set to NOT CHARGING upon charger error
+		 * or charging has stopped.
+		 */
+		status = POWER_SUPPLY_STATUS_NOT_CHARGING;
+	} else {
+		if ((val & STAT_C_CHG_MASK) >> STAT_C_CHG_SHIFT) {
+			/*
+			 * set to charging if battery is in pre-charge,
+			 * fast charge or taper charging mode.
+			 */
+			status = POWER_SUPPLY_STATUS_CHARGING;
+		} else if (val & STAT_C_CHG_TERM) {
+			/*
+			 * set the status to FULL if battery is not in pre
+			 * charge, fast charge or taper charging mode AND
+			 * charging is terminated at least once.
+			 */
+			status = POWER_SUPPLY_STATUS_FULL;
+		} else {
+			/*
+			 * in this case no charger error or termination
+			 * occured but charging is not in progress!!!
+			 */
+			status = POWER_SUPPLY_STATUS_NOT_CHARGING;
+		}
+	}
+
+	return status;
+}
+
 static int smb347_battery_get_property(struct power_supply *psy,
 				       enum power_supply_property prop,
 				       union power_supply_propval *val)
@@ -1003,14 +1074,10 @@ static int smb347_battery_get_property(struct power_supply *psy,
 
 	switch (prop) {
 	case POWER_SUPPLY_PROP_STATUS:
-		if (!smb347_is_ps_online(smb)) {
-			val->intval = POWER_SUPPLY_STATUS_DISCHARGING;
-			break;
-		}
-		if (smb347_charging_status(smb))
-			val->intval = POWER_SUPPLY_STATUS_CHARGING;
-		else
-			val->intval = POWER_SUPPLY_STATUS_FULL;
+		ret = smb347_get_charging_status(smb);
+		if (ret < 0)
+			return ret;
+		val->intval = ret;
 		break;
 
 	case POWER_SUPPLY_PROP_CHARGE_TYPE: