Documentation: power: max77693-charger: Document exported sysfs entry

Document the settings exported by max77693 charger driver through sysfs
entries:
 - fast_charge_timer
 - top_off_threshold_current
 - top_off_timer
Signed-off-by: NKrzysztof Kozlowski <k.kozlowski@samsung.com>
Signed-off-by: NSebastian Reichel <sre@kernel.org>

Documentation/ABI/testing/sysfs-class-power

@@ -32,3 +32,45 @@ Description:
 		Valid values:
 		- 5, 6 or 7 (hours),
 		- 0: disabled.
+
+What:		/sys/class/power_supply/max77693-charger/device/fast_charge_timer
+Date:		January 2015
+KernelVersion:	3.19.0
+Contact:	Krzysztof Kozlowski <k.kozlowski@samsung.com>
+Description:
+		This entry shows and sets the maximum time the max77693
+		charger operates in fast-charge mode. When the timer expires
+		the device will terminate fast-charge mode (charging current
+		will drop to 0 A) and will trigger interrupt.
+
+		Valid values:
+		- 4 - 16 (hours), step by 2 (rounded down)
+		- 0: disabled.
+
+What:		/sys/class/power_supply/max77693-charger/device/top_off_threshold_current
+Date:		January 2015
+KernelVersion:	3.19.0
+Contact:	Krzysztof Kozlowski <k.kozlowski@samsung.com>
+Description:
+		This entry shows and sets the charging current threshold for
+		entering top-off charging mode. When charging current in fast
+		charge mode drops below this value, the charger will trigger
+		interrupt and start top-off charging mode.
+
+		Valid values:
+		- 100000 - 200000 (microamps), step by 25000 (rounded down)
+		- 200000 - 350000 (microamps), step by 50000 (rounded down)
+		- 0: disabled.
+
+What:		/sys/class/power_supply/max77693-charger/device/top_off_timer
+Date:		January 2015
+KernelVersion:	3.19.0
+Contact:	Krzysztof Kozlowski <k.kozlowski@samsung.com>
+Description:
+		This entry shows and sets the maximum time the max77693
+		charger operates in top-off charge mode. When the timer expires
+		the device will terminate top-off charge mode (charging current
+		will drop to 0 A) and will trigger interrupt.
+
+		Valid values:
+		- 0 - 70 (minutes), step by 10 (rounded down)