power: supply: axp20x_usb_power: Allow offlining

AXP803/AXP813 have a flag that enables/disables the USB power supply
input. Allow control of this flag via the ONLINE property on those
variants.

It may be necessary to offline the USB power supply input when using
the USB port in OTG mode, or to allow userspace to disable charging.

When the USB VBUS input is disabled via the PATH_SEL bit, the VBUS_USED
bit in PWR_INPUT_STATUS is cleared, so there is no change needed when
getting the property.
Reviewed-by: Chen-Yu Tsai <wens@csie.org>
Signed-off-by: Samuel Holland <samuel@sholland.org>
Signed-off-by: Sebastian Reichel <sebastian.reichel@collabora.com>

drivers/power/supply/axp20x_usb_power.c

@@ -29,6 +29,9 @@
 
 #define AXP20X_USB_STATUS_VBUS_VALID	BIT(2)
 
+#define AXP20X_VBUS_PATH_SEL		BIT(7)
+#define AXP20X_VBUS_PATH_SEL_OFFSET	7
+
 #define AXP20X_VBUS_VHOLD_uV(b)		(4000000 + (((b) >> 3) & 7) * 100000)
 #define AXP20X_VBUS_VHOLD_MASK		GENMASK(5, 3)
 #define AXP20X_VBUS_VHOLD_OFFSET	3
@@ -263,6 +266,16 @@ static int axp20x_usb_power_get_property(struct power_supply *psy,
 	return 0;
 }
 
+static int axp813_usb_power_set_online(struct axp20x_usb_power *power,
+				       int intval)
+{
+	int val = !intval << AXP20X_VBUS_PATH_SEL_OFFSET;
+
+	return regmap_update_bits(power->regmap,
+				  AXP20X_VBUS_IPSOUT_MGMT,
+				  AXP20X_VBUS_PATH_SEL, val);
+}
+
 static int axp20x_usb_power_set_voltage_min(struct axp20x_usb_power *power,
 					    int intval)
 {
@@ -344,6 +357,11 @@ static int axp20x_usb_power_set_property(struct power_supply *psy,
 	struct axp20x_usb_power *power = power_supply_get_drvdata(psy);
 
 	switch (psp) {
+	case POWER_SUPPLY_PROP_ONLINE:
+		if (power->axp20x_id != AXP813_ID)
+			return -EINVAL;
+		return axp813_usb_power_set_online(power, val->intval);
+
 	case POWER_SUPPLY_PROP_VOLTAGE_MIN:
 		return axp20x_usb_power_set_voltage_min(power, val->intval);
 
@@ -363,6 +381,18 @@ static int axp20x_usb_power_set_property(struct power_supply *psy,
 static int axp20x_usb_power_prop_writeable(struct power_supply *psy,
 					   enum power_supply_property psp)
 {
+	struct axp20x_usb_power *power = power_supply_get_drvdata(psy);
+
+	/*
+	 * The VBUS path select flag works differently on on AXP288 and newer:
+	 *  - On AXP20x and AXP22x, the flag enables VBUS (ignoring N_VBUSEN).
+	 *  - On AXP288 and AXP8xx, the flag disables VBUS (ignoring N_VBUSEN).
+	 * We only expose the control on variants where it can be used to force
+	 * the VBUS input offline.
+	 */
+	if (psp == POWER_SUPPLY_PROP_ONLINE)
+		return power->axp20x_id == AXP813_ID;
+
 	return psp == POWER_SUPPLY_PROP_VOLTAGE_MIN ||
 	       psp == POWER_SUPPLY_PROP_CURRENT_MAX;
 }