[PATCH v2] smb347_charger: fix battery status reporting logic for charger faults

[Ramakrishna Pallala <ramakrishna.pallala@intel.com>]

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.

Resending this patch because previous patch missed Anton's attention

Signed-off-by: Ramakrishna Pallala <ramakrishna.pallala@intel.com>
---
 drivers/power/smb347-charger.c |   97 +++++++++++++++++++++++++++++++++------
 1 files changed, 82 insertions(+), 15 deletions(-)

diff --git a/drivers/power/smb347-charger.c b/drivers/power/smb347-charger.c
index 332dd01..c5b482b 100644
--- a/drivers/power/smb347-charger.c
+++ b/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:
-- 
1.7.0.4