dt-bindings: mfd: mediatek: Add MT6323 Power Controller

- Add Power Controller section to existing binding document.
- Add MT6323 PWRC bindings document with example.
Suggested-by: Frank Wunderlich <frank-w@public-files.de>
Signed-off-by: Josef Friedl <josef.friedl@speed.at>
Signed-off-by: Frank Wunderlich <frank-w@public-files.de>
Signed-off-by: Lee Jones <lee.jones@linaro.org>

Documentation/devicetree/bindings/mfd/mt6397.txt

@@ -8,6 +8,7 @@ MT6397/MT6323 is a multifunction device with the following sub modules:
 - Clock
 - LED
 - Keys
+- Power controller
 
 It is interfaced to host controller using SPI interface by a proprietary hardware
 called PMIC wrapper or pwrap. MT6397/MT6323 MFD is a child device of pwrap.
@@ -48,6 +49,11 @@ Optional subnodes:
 		- compatible: "mediatek,mt6397-keys" or "mediatek,mt6323-keys"
 	see ../input/mtk-pmic-keys.txt
 
+- power-controller
+	Required properties:
+		- compatible: "mediatek,mt6323-pwrc"
+	For details, see ../power/reset/mt6323-poweroff.txt
+
 Example:
 	pwrap: pwrap@1000f000 {
 		compatible = "mediatek,mt8135-pwrap";

Documentation/devicetree/bindings/power/reset/mt6323-poweroff.txt

+Device Tree Bindings for Power Controller on MediaTek PMIC
+
+The power controller which could be found on PMIC is responsible for externally
+powering off or on the remote MediaTek SoC through the circuit BBPU.
+
+Required properties:
+- compatible: Should be one of follows
+       "mediatek,mt6323-pwrc": for MT6323 PMIC
+
+Example:
+
+       pmic {
+               compatible = "mediatek,mt6323";
+
+               ...
+
+               power-controller {
+                       compatible = "mediatek,mt6323-pwrc";
+               };
+       }