devicetree: bindings: bd718x7: document HW state related ROHM specific properties

Add ROHM BD71837 / BD71847 specific device tree bindings for
controlling the PMIC shutdown/reset states and voltages for
different HW states. The PMIC was designed to be used with NXP
i.MX8 SoC and it supports SNVS low power state which seems to
be typical for NXP i.MX SoCs. However, when SNVS is used we must
not allow SW to control enabling/disabling those regulators which
are crucial for system to boot as there is a HW limitation which
causes SW controlled regulators to be kept shut down after SNVS
reset.

Allow setting the SNVS to be used as reset target state and allow
marking those regulators which are critical for boot.

Signed-off-by: Matti Vaittinen <matti.vaittinen@fi.rohmeurope.com>
Tested-by: Angus Ainslie <angus@akkea.ca>
Reviewed-by: Angus Ainslie <angus@akkea.ca>
Signed-off-by: Mark Brown <broonie@kernel.org>

1 files changed, 17 insertions, 0 deletions

diff --git a/Documentation/devicetree/bindings/mfd/rohm,bd71837-pmic.txt b/Documentation/devicetree/bindings/mfd/rohm,bd71837-pmic.txt
index a4b056761eaa..d5f68ac78d15 100644
--- a/Documentation/devicetree/bindings/mfd/rohm,bd71837-pmic.txt
+++ b/Documentation/devicetree/bindings/mfd/rohm,bd71837-pmic.txt
@@ -23,6 +23,20 @@ Required properties:
 
 Optional properties:
 - clock-output-names	: Should contain name for output clock.
+- rohm,reset-snvs-powered : Transfer BD718x7 to SNVS state at reset.
+
+The BD718x7 supports two different HW states as reset target states. States
+are called as SNVS and READY. At READY state all the PMIC power outputs go
+down and OTP is reload. At the SNVS state all other logic and external
+devices apart from the SNVS power domain are shut off. Please refer to NXP
+i.MX8 documentation for further information regarding SNVS state. When a
+reset is done via SNVS state the PMIC OTP data is not reload. This causes
+power outputs that have been under SW control to stay down when reset has
+switched power state to SNVS. If reset is done via READY state the power
+outputs will be returned to HW control by OTP loading. Thus the reset
+target state is set to READY by default. If SNVS state is used the boot
+crucial regulators must have the regulator-always-on and regulator-boot-on
+properties set in regulator node.
 
 Example:
 
@@ -43,6 +57,7 @@ Example:
 		#clock-cells = <0>;
 		clocks = <&osc 0>;
 		clock-output-names = "bd71837-32k-out";
+		rohm,reset-snvs-powered;
 
 		regulators {
 			buck1: BUCK1 {
@@ -50,8 +65,10 @@ Example:
 				regulator-min-microvolt = <700000>;
 				regulator-max-microvolt = <1300000>;
 				regulator-boot-on;
+				regulator-always-on;
 				regulator-ramp-delay = <1250>;
 			};
+			// [...]
 		};
 	};