[PATCH v2 16/17] power: axp20x_battery: Support battery status without fuel gauge

[Aidan MacDonald <aidanmacdonald.0x0@gmail.com>]

Add a "has_fg" flag to indicate that the chip has a fuel gauge.
Report battery full status on chips with no fuel gauge using the
battery voltage.

Signed-off-by: Aidan MacDonald <aidanmacdonald.0x0@gmail.com>
---
 drivers/power/supply/axp20x_battery.c | 34 ++++++++++++++++++++++++++-
 1 file changed, 33 insertions(+), 1 deletion(-)

diff --git a/drivers/power/supply/axp20x_battery.c b/drivers/power/supply/axp20x_battery.c
index 87fb958f2224..e9547e2d7c48 100644
--- a/drivers/power/supply/axp20x_battery.c
+++ b/drivers/power/supply/axp20x_battery.c
@@ -62,6 +62,7 @@ struct axp_data {
 	int	ccc_scale;
 	int	ccc_offset;
 	const int *ccc_table;
+	bool	has_fg;
 	bool	has_fg_valid;
 	int	(*get_max_voltage)(struct axp20x_batt_ps *batt, int *val);
 	int	(*set_max_voltage)(struct axp20x_batt_ps *batt, int val);
@@ -190,7 +191,7 @@ static int axp20x_battery_get_prop(struct power_supply *psy,
 				   union power_supply_propval *val)
 {
 	struct axp20x_batt_ps *axp20x_batt = power_supply_get_drvdata(psy);
-	int ret = 0, reg, val1;
+	int ret = 0, reg, val1, val2;
 
 	switch (psp) {
 	case POWER_SUPPLY_PROP_PRESENT:
@@ -224,6 +225,34 @@ static int axp20x_battery_get_prop(struct power_supply *psy,
 			return 0;
 		}
 
+		/*
+		 * If the chip does not have a fuel gauge, we check battery full status
+		 * using voltage instead.
+		 */
+		if (!axp20x_batt->data->has_fg) {
+			ret = axp20x_batt->data->get_max_voltage(axp20x_batt, &val1);
+			if (ret)
+				return ret;
+
+			ret = iio_read_channel_processed(axp20x_batt->batt_v, &val2);
+			if (ret)
+				return ret;
+
+			/* IIO subsystem reports voltage in mV but we need uV */
+			val2 *= 1000;
+
+			/*
+			 * According to the AXP192 datasheet, charging will restart if
+			 * the battery voltage drops below V_rch = V_tgt - 0.1 V, so we
+			 * report the battery is full if its voltage is at least V_rch.
+			 */
+			if (val2 >= val1 - 100000)
+				val->intval = POWER_SUPPLY_STATUS_FULL;
+			else
+				val->intval = POWER_SUPPLY_STATUS_NOT_CHARGING;
+			break;
+		}
+
 		ret = regmap_read(axp20x_batt->regmap, AXP20X_FG_RES, &val1);
 		if (ret)
 			return ret;
@@ -546,6 +575,7 @@ static const struct power_supply_desc axp20x_batt_ps_desc = {
 static const struct axp_data axp209_data = {
 	.ccc_scale = 100000,
 	.ccc_offset = 300000,
+	.has_fg = true,
 	.get_max_voltage = axp20x_battery_get_max_voltage,
 	.set_max_voltage = axp20x_battery_set_max_voltage,
 };
@@ -553,6 +583,7 @@ static const struct axp_data axp209_data = {
 static const struct axp_data axp221_data = {
 	.ccc_scale = 150000,
 	.ccc_offset = 300000,
+	.has_fg = true,
 	.has_fg_valid = true,
 	.get_max_voltage = axp22x_battery_get_max_voltage,
 	.set_max_voltage = axp22x_battery_set_max_voltage,
@@ -561,6 +592,7 @@ static const struct axp_data axp221_data = {
 static const struct axp_data axp813_data = {
 	.ccc_scale = 200000,
 	.ccc_offset = 200000,
+	.has_fg = true,
 	.has_fg_valid = true,
 	.get_max_voltage = axp813_battery_get_max_voltage,
 	.set_max_voltage = axp20x_battery_set_max_voltage,
-- 
2.35.1