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Subject[RFC PATCH v1 1/3] 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>
---
.../devicetree/bindings/mfd/rohm,bd71837-pmic.txt | 17 ++++++++++
.../bindings/regulator/rohm,bd71837-regulator.txt | 36 ++++++++++++++++++++++
2 files changed, 53 insertions(+)

diff --git a/Documentation/devicetree/bindings/mfd/rohm,bd71837-pmic.txt b/Documentation/devicetree/bindings/mfd/rohm,bd71837-pmic.txt
index a4b056761eaa..2aff8287fdd8 100644
--- a/Documentation/devicetree/bindings/mfd/rohm,bd71837-pmic.txt
+++ b/Documentation/devicetree/bindings/mfd/rohm,bd71837-pmic.txt
@@ -23,6 +23,23 @@ 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 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.
+
+At READY state all the PMIC power outputs go down and OTP is reload. There
+is a HW quirk in BD718x7 which causes power outputs which 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 set 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 should have
+"rohm,regulator-crucial-for-boot" property set in regulator node. Please
+see the ./regulator/rohm,bd71837-regulator.txt for details of regulator
+bindings.

Example:

diff --git a/Documentation/devicetree/bindings/regulator/rohm,bd71837-regulator.txt b/Documentation/devicetree/bindings/regulator/rohm,bd71837-regulator.txt
index 4b98ca26e61a..8ff692891dea 100644
--- a/Documentation/devicetree/bindings/regulator/rohm,bd71837-regulator.txt
+++ b/Documentation/devicetree/bindings/regulator/rohm,bd71837-regulator.txt
@@ -27,8 +27,44 @@ BUCK1, BUCK2, BUCK3, BUCK4, BUCK5, BUCK6
LDO1, LDO2, LDO3, LDO4, LDO5, LDO6

Optional properties:
+- rohm,regulator-crucial-for-boot : Any regulators which are required to stay
+ enabled for system to boot must be excluded
+ from SW control by this property if SNVS
+ state is used as reset target. Please see
+ the ../mfd/rohm,bd71837-pmic.txt for more
+ details.
+- rohm,dvs-run-voltage : PMIC default "RUN" state voltage in uV.
+ See below table for bucks which support this.
+- rohm,dvs-idle-voltage : PMIC default "IDLE" state voltage in uV.
+ See below table for bucks which support this.
+- rohm,dvs-suspend-voltage : PMIC default "SUSPEND" state voltage in uV.
+ See below table for bucks which support this.
- Any optional property defined in bindings/regulator/regulator.txt

+Supported default DVS states:
+
+BD71837:
+buck | dvs-run-voltage | dvs-idle-voltage | dvs-suspend-voltage
+-----------------------------------------------------------------------------
+1 | supported | supported | supported
+----------------------------------------------------------------------------
+2 | supported | supported | not supported
+----------------------------------------------------------------------------
+3 | supported | not supported | not supported
+----------------------------------------------------------------------------
+4 | supported | not supported | not supported
+----------------------------------------------------------------------------
+rest | not supported | not supported | not supported
+
+BD71847:
+buck | dvs-run-voltage | dvs-idle-voltage | dvs-suspend-voltage
+-----------------------------------------------------------------------------
+1 | supported | supported | supported
+----------------------------------------------------------------------------
+2 | supported | supported | not supported
+----------------------------------------------------------------------------
+rest | not supported | not supported | not supported
+
Example:
regulators {
buck1: BUCK1 {
--
2.14.3

--
Matti Vaittinen, Linux device drivers
ROHM Semiconductors, Finland SWDC
Kiviharjunlenkki 1E
90220 OULU
FINLAND

~~~ "I don't think so," said Rene Descartes. Just then, he vanished ~~~

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