mfd: axp20x: Add supplied-from property to axp288_fuel_gauge cell

The power-supply framework has the notion of one power-supply device
being supplied by another. A typical example of this is a charger
charging a battery.

A tablet getting plugged in to charge (or plugged out) only results in
events seen by the axp288_charger device / MFD cell. Which means that
a change udev-event only gets send for the charger power-supply class
device, not for the battery (the axp288_fuel_gauge device).

The axp288_fuel_gauge does have an external_power_change'd callback
which will generate a change udev-event when called. But before this
commit this never got called because the power-supply core only calls
this when a power-supply class device's supplier changes and the
supplier link from axp288_charger to axp288_fuel_gauge was missing.

Add a "supplied-from" property to axp288_fuel_gauge cell, pointing
to the "axp288_charger" power-supply class device, so that the
axp288_fuel_gauge's external_power_change'd callback gets called on
axp288_charger state changes.
Signed-off-by: Hans de Goede <hdegoede@redhat.com>
Reviewed-by: Chen-Yu Tsai <wens@csie.org>
Signed-off-by: Lee Jones <lee.jones@linaro.org>

drivers/mfd/axp20x.c

@@ -700,6 +700,18 @@ static const struct resource axp288_charger_resources[] = {
 	DEFINE_RES_IRQ(AXP288_IRQ_CBTO),
 };
 
+static const char * const axp288_fuel_gauge_suppliers[] = { "axp288_charger" };
+
+static const struct property_entry axp288_fuel_gauge_properties[] = {
+	PROPERTY_ENTRY_STRING_ARRAY("supplied-from", axp288_fuel_gauge_suppliers),
+	{ }
+};
+
+static const struct software_node axp288_fuel_gauge_sw_node = {
+	.name = "axp288_fuel_gauge",
+	.properties = axp288_fuel_gauge_properties,
+};
+
 static const struct mfd_cell axp288_cells[] = {
 	{
 		.name		= "axp288_adc",
@@ -717,6 +729,7 @@ static const struct mfd_cell axp288_cells[] = {
 		.name		= "axp288_fuel_gauge",
 		.num_resources	= ARRAY_SIZE(axp288_fuel_gauge_resources),
 		.resources	= axp288_fuel_gauge_resources,
+		.swnode		= &axp288_fuel_gauge_sw_node,
 	}, {
 		.name		= "axp221-pek",
 		.num_resources	= ARRAY_SIZE(axp288_power_button_resources),