dt-bindings: mfd: bd9571mwv: Document DDR Backup Mode properties

Document the new optional properties related to DDR Backup Mode and
toggle/momentary power switches.
Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
Reviewed-by: Rob Herring <robh@kernel.org>
Acked-by: Lee Jones <lee.jones@linaro.org>
Signed-off-by: Mark Brown <broonie@kernel.org>

Documentation/devicetree/bindings/mfd/bd9571mwv.txt

@@ -25,6 +25,25 @@ Required properties:
 			    Each child node is defined using the standard
 			    binding for regulators.
 
+Optional properties:
+  - rohm,ddr-backup-power : Value to use for DDR-Backup Power (default 0).
+			    This is a bitmask that specifies which DDR power
+			    rails need to be kept powered when backup mode is
+			    entered, for system suspend:
+			      - bit 0: DDR0
+			      - bit 1: DDR1
+			      - bit 2: DDR0C
+			      - bit 3: DDR1C
+			    These bits match the KEEPON_DDR* bits in the
+			    documentation for the "BKUP Mode Cnt" register.
+  - rohm,rstbmode-level: The RSTB signal is configured for level mode, to
+			 accommodate a toggle power switch (the RSTBMODE pin is
+			 strapped low).
+  - rohm,rstbmode-pulse: The RSTB signal is configured for pulse mode, to
+			 accommodate a momentary power switch (the RSTBMODE pin
+			 is strapped high).
+			 The two properties above are mutually exclusive.
+
 Example:
 
 	pmic: pmic@30 {
@@ -36,6 +55,8 @@ Example:
 		#interrupt-cells = <2>;
 		gpio-controller;
 		#gpio-cells = <2>;
+		rohm,ddr-backup-power = <0xf>;
+		rohm,rstbmode-pulse;
 
 		regulators {
 			dvfs: dvfs {