power_supply: rt9455_charger: Properly notify userspace about charging events

power_supply: rt9455_charger: Properly notify userspace about charging events

Charging events this patch refers to are:
- charger is connected to/disconnected from the power source
- battery is reconnected to the charger, after it was absent.

When the charger is connected to/disconnected from the power source, CHRVPI
interrupt occurs and PWR_RDY bit is either set or cleared. PWR_RDY bit is
updated after 1-2 seconds CHRVPI interrupt has occurred.
power_supply_changed() should be called after PWR_RDY bit is updated.
/sys/class/power_supply/rt9455-charger/online file displays the value of
PWR_RDY bit.
This way, if the userspace is notified that a charging event has occurred
and the userspace reads /sys/class/power_supply/rt9455-charger/online file,
this file is properly updated when the userspace reads it.
This is the reason why power_supply_changed() is called in
rt9455_pwr_rdy_work_callback(), instead of being called in interrupt
handler.

Since no interrupt is triggered when the battery is reconnected to the
charger, the userspace is never notified that the battery is reconnected.
This is why power_supply_changed() is called in
rt9455_max_charging_time_work_callback(), so that the userspace is notified
that the battery is reconnected.

Signed-off-by: Anda-Maria Nicolae <anda-maria.nicolae@intel.com>
Reviewed-by: Krzysztof Kozlowski <k.kozlowski@samsung.com>
Signed-off-by: Sebastian Reichel <sre@kernel.org>