linux-kernel - [PATCH 1/2] dt-bindings: reset: syscon-reboot: support reset modes

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Message-Id: <20250226-syscon-reboot-reset-mode-v1-1-91c1b62166ae@linaro.org>
Date: Wed, 26 Feb 2025 14:08:20 +0000
From: André Draszik <andre.draszik@...aro.org>
To: Sebastian Reichel <sre@...nel.org>, Rob Herring <robh@...nel.org>, 
 Krzysztof Kozlowski <krzk+dt@...nel.org>, 
 Conor Dooley <conor+dt@...nel.org>
Cc: Peter Griffin <peter.griffin@...aro.org>, 
 Tudor Ambarus <tudor.ambarus@...aro.org>, 
 Will McVicker <willmcvicker@...gle.com>, kernel-team@...roid.com, 
 linux-pm@...r.kernel.org, devicetree@...r.kernel.org, 
 linux-kernel@...r.kernel.org, 
 André Draszik <andre.draszik@...aro.org>
Subject: [PATCH 1/2] dt-bindings: reset: syscon-reboot: support reset modes

Add support for specifying different register/mask/value combinations
for different types of reset.

In particular, update the binding to allow platforms to specify the
following reset modes: soft, warm, cold, hard.

Linux can perform different types of reset using its reboot= kernel
command line argument, and some platforms also wish to reset
differently based on whether or not e.g. contents of RAM should be
retained across the reboot.

The new properties match the existing properties, just prefixed with
one of the reset modes mentioned above.

Signed-off-by: André Draszik <andre.draszik@...aro.org>
---
 .../bindings/power/reset/syscon-reboot.yaml        | 74 ++++++++++++++++++++++
 1 file changed, 74 insertions(+)

diff --git a/Documentation/devicetree/bindings/power/reset/syscon-reboot.yaml b/Documentation/devicetree/bindings/power/reset/syscon-reboot.yaml
index 19d3093e6cd2f7e39d94c56636dc202a4427ffc3..a34b1c08b7e0f34574a0257e13c02fceac0243ae 100644
--- a/Documentation/devicetree/bindings/power/reset/syscon-reboot.yaml
+++ b/Documentation/devicetree/bindings/power/reset/syscon-reboot.yaml
@@ -18,6 +18,11 @@ description: |+
   parental dt-node. So the SYSCON reboot node should be represented as a
   sub-node of a "syscon", "simple-mfd" node. Though the regmap property
   pointing to the system controller node is also supported.
+  This also supports specification of separate sets of register/mask/value
+  pairs for different types of reset: cold, hard, soft and warm, using
+  the respective properties with the respective reset type prefix. If prefixed
+  properties are not specified for a reset type, the non-prefixed properties
+  will be used for that reset type.
 
 properties:
   compatible:
@@ -49,12 +54,41 @@ properties:
   priority:
     default: 192
 
+patternProperties:
+  "^(cold|hard|soft|warm)-(mask|offset|value)$":
+    $ref: /schemas/types.yaml#/definitions/uint32
+    description:
+      Optional alternative offset / mask / value combinations for specific
+      reboot modes. The mask is optional.
+
+  "^(cold|hard|soft|warm)-reg$":
+    description:
+      Optional alternative base address and size for the reboot register for
+      specific reboot modes.
+
 oneOf:
   - required:
       - offset
   - required:
       - reg
 
+dependencies:
+  cold-mask: [ cold-value ]
+  cold-offset: [ cold-value ]
+  cold-reg: [ cold-value ]
+
+  hard-mask: [ hard-value ]
+  hard-offset: [ hard-value ]
+  hard-reg: [ hard-value ]
+
+  soft-mask: [ soft-value ]
+  soft-offset: [ soft-value ]
+  soft-reg: [ soft-value ]
+
+  warm-mask: [ warm-value ]
+  warm-offset: [ warm-value ]
+  warm-reg: [ warm-value ]
+
 required:
   - compatible
 
@@ -70,6 +104,46 @@ allOf:
       required:
         - value
 
+  - if:
+      required:
+        - cold-value
+    then:
+      oneOf:
+        - required:
+          - cold-offset
+        - required:
+          - cold-reg
+
+  - if:
+      required:
+        - hard-value
+    then:
+      oneOf:
+        - required:
+          - hard-offset
+        - required:
+          - hard-reg
+
+  - if:
+      required:
+        - soft-value
+    then:
+      oneOf:
+        - required:
+          - soft-offset
+        - required:
+          - soft-reg
+
+  - if:
+      required:
+        - warm-value
+    then:
+      oneOf:
+        - required:
+          - warm-offset
+        - required:
+          - warm-reg
+
 examples:
   - |
     reboot {

-- 
2.48.1.658.g4767266eb4-goog