[PATCH v4 3/3] Documentation: power: rt9756: Document exported sysfs entries

[<cy_huang@richtek.com>]

From: ChiYuan Huang <cy_huang@richtek.com>

Document the settings exported by rt9756 charger driver through sysfs
entries:

- watchdog_timer
- operation_mode

Signed-off-by: ChiYuan Huang <cy_huang@richtek.com>
---
V3
- Remove customized description for battery voltage and current
---
 .../ABI/testing/sysfs-class-power-rt9756      | 30 +++++++++++++++++++
 1 file changed, 30 insertions(+)
 create mode 100644 Documentation/ABI/testing/sysfs-class-power-rt9756

diff --git a/Documentation/ABI/testing/sysfs-class-power-rt9756 b/Documentation/ABI/testing/sysfs-class-power-rt9756
new file mode 100644
index 000000000000..c4d6c2b4715d
--- /dev/null
+++ b/Documentation/ABI/testing/sysfs-class-power-rt9756
@@ -0,0 +1,30 @@
+What:		/sys/class/power_supply/rt9756-*/watchdog_timer
+Date:		Dec 2025
+KernelVersion:	6.19
+Contact:	ChiYuan Huang <cy_huang@richtek.com>
+Description:
+		This entry shows and sets the watchdog timer when rt9756 charger
+		operates in charging mode. When the timer expires, the device
+		will disable the charging. To prevent the timer expires, any
+		host communication can make the timer restarted.
+
+		Access: Read, Write
+
+		Valid values:
+		- 500, 1000, 5000, 30000, 40000, 80000, 128000 or 255000 (milliseconds),
+		- 0: disabled
+
+What:		/sys/class/power_supply/rt9756-*/operation_mode
+Date:		Dec 2025
+KernelVersion:	6.19
+Contact:	ChiYuan Huang <cy_huang@richtek.com>
+Description:
+		This entry shows and set the operation mode when rt9756 charger
+		operates in charging phase. If 'bypass' mode is used, internal
+		path will connect vbus directly to vbat. Else, default 'div2'
+		mode for the switch-cap charging.
+
+		Access: Read, Write
+
+		Valid values:
+		- 'bypass' or 'div2'
-- 
2.34.1