power: supply: axp20x_battery: allow disabling battery charging

Allow disabling and re-enabling battery charging of an axp209 PMIC
through a writable status property. With the current driver code
charging is always on.

This works on the axp209 of Banana {Pi M1+,Pro} and should work on all
AXP chips.

Signed-off-by: Hermann.Lauer@uni-heidelberg.de
Signed-off-by: Sebastian Reichel <sebastian.reichel@collabora.com>

drivers/power/supply/axp20x_battery.c

@@ -40,6 +40,7 @@
 #define AXP209_FG_PERCENT		GENMASK(6, 0)
 #define AXP22X_FG_VALID			BIT(7)
 
+#define AXP20X_CHRG_CTRL1_ENABLE	BIT(7)
 #define AXP20X_CHRG_CTRL1_TGT_VOLT	GENMASK(6, 5)
 #define AXP20X_CHRG_CTRL1_TGT_4_1V	(0 << 5)
 #define AXP20X_CHRG_CTRL1_TGT_4_15V	(1 << 5)
@@ -468,7 +469,18 @@ static int axp20x_battery_set_prop(struct power_supply *psy,
 	case POWER_SUPPLY_PROP_CONSTANT_CHARGE_CURRENT_MAX:
 		return axp20x_set_max_constant_charge_current(axp20x_batt,
 							      val->intval);
-
+	case POWER_SUPPLY_PROP_STATUS:
+		switch (val->intval) {
+		case POWER_SUPPLY_STATUS_CHARGING:
+			return regmap_update_bits(axp20x_batt->regmap, AXP20X_CHRG_CTRL1,
+				AXP20X_CHRG_CTRL1_ENABLE, AXP20X_CHRG_CTRL1_ENABLE);
+
+		case POWER_SUPPLY_STATUS_DISCHARGING:
+		case POWER_SUPPLY_STATUS_NOT_CHARGING:
+			return regmap_update_bits(axp20x_batt->regmap, AXP20X_CHRG_CTRL1,
+				AXP20X_CHRG_CTRL1_ENABLE, 0);
+		}
+		fallthrough;
 	default:
 		return -EINVAL;
 	}
@@ -491,7 +503,8 @@ static enum power_supply_property axp20x_battery_props[] = {
 static int axp20x_battery_prop_writeable(struct power_supply *psy,
 					 enum power_supply_property psp)
 {
-	return psp == POWER_SUPPLY_PROP_VOLTAGE_MIN_DESIGN ||
+	return psp == POWER_SUPPLY_PROP_STATUS ||
+	       psp == POWER_SUPPLY_PROP_VOLTAGE_MIN_DESIGN ||
 	       psp == POWER_SUPPLY_PROP_VOLTAGE_MAX_DESIGN ||
 	       psp == POWER_SUPPLY_PROP_CONSTANT_CHARGE_CURRENT ||
 	       psp == POWER_SUPPLY_PROP_CONSTANT_CHARGE_CURRENT_MAX;