linux-kernel - [PATCH v2 1/6] dt-bindings: pwm: amlogic: fix s4 bindings

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Date:   Fri, 17 Nov 2023 13:59:11 +0100
From:   Jerome Brunet <jbrunet@...libre.com>
To:     Thierry Reding <thierry.reding@...il.com>,
        Neil Armstrong <neil.armstrong@...aro.org>,
        Rob Herring <robh+dt@...nel.org>,
        Krzysztof Kozlowski <krzysztof.kozlowski+dt@...aro.org>,
        Conor Dooley <conor+dt@...nel.org>
Cc:     Jerome Brunet <jbrunet@...libre.com>,
        Kevin Hilman <khilman@...libre.com>,
        devicetree@...r.kernel.org, linux-kernel@...r.kernel.org,
        linux-amlogic@...ts.infradead.org, linux-pwm@...r.kernel.org,
        JunYi Zhao <junyi.zhao@...ogic.com>
Subject: [PATCH v2 1/6] dt-bindings: pwm: amlogic: fix s4 bindings

s4 has been added to the compatible list while converting the Amlogic PWM
binding documentation from txt to yaml.

However, on the s4, the clock bindings have different meaning compared to
the previous SoCs.

On the previous SoCs the clock bindings used to describe which input the
PWM channel multiplexer should pick among its possible parents.

This is very much tied to the driver implementation, instead of describing
the HW for what it is. When support for the Amlogic PWM was first added,
how to deal with clocks through DT was not as clear as it nowadays.
The Linux driver now ignores this DT setting, but still relies on the
hard-coded list of clock sources.

On the s4, the input multiplexer is gone. The clock bindings actually
describe the clock as it exists, not a setting. The property has a
different meaning, even if it is still 2 clocks and it would pass the check
when support is actually added.

Also the s4 cannot work if the clocks are not provided, so the property no
longer optional.

Finally, for once it makes sense to see the input as being numbered
somehow. No need to bother with clock-names on the s4 type of PWM.

Fixes: 43a1c4ff3977 ("dt-bindings: pwm: Convert Amlogic Meson PWM binding")
Signed-off-by: Jerome Brunet <jbrunet@...libre.com>
---
 .../devicetree/bindings/pwm/pwm-amlogic.yaml  | 69 ++++++++++++++++---
 1 file changed, 60 insertions(+), 9 deletions(-)

diff --git a/Documentation/devicetree/bindings/pwm/pwm-amlogic.yaml b/Documentation/devicetree/bindings/pwm/pwm-amlogic.yaml
index 527864a4d855..387976ed36d5 100644
--- a/Documentation/devicetree/bindings/pwm/pwm-amlogic.yaml
+++ b/Documentation/devicetree/bindings/pwm/pwm-amlogic.yaml
@@ -9,9 +9,6 @@ title: Amlogic PWM
 maintainers:
   - Heiner Kallweit <hkallweit1@...il.com>
 
-allOf:
-  - $ref: pwm.yaml#
-
 properties:
   compatible:
     oneOf:
@@ -43,12 +40,8 @@ properties:
     maxItems: 2
 
   clock-names:
-    oneOf:
-      - items:
-          - enum: [clkin0, clkin1]
-      - items:
-          - const: clkin0
-          - const: clkin1
+    minItems: 1
+    maxItems: 2
 
   "#pwm-cells":
     const: 3
@@ -57,6 +50,57 @@ required:
   - compatible
   - reg
 
+allOf:
+  - $ref: pwm.yaml#
+
+  - if:
+      properties:
+        compatible:
+          contains:
+            enum:
+              - amlogic,meson8-pwm
+              - amlogic,meson8b-pwm
+              - amlogic,meson-gxbb-pwm
+              - amlogic,meson-gxbb-ao-pwm
+              - amlogic,meson-axg-ee-pwm
+              - amlogic,meson-axg-ao-pwm
+              - amlogic,meson-g12a-ee-pwm
+              - amlogic,meson-g12a-ao-pwm-ab
+              - amlogic,meson-g12a-ao-pwm-cd
+              - amlogic,meson-gx-pwm
+              - amlogic,meson-gx-ao-pwm
+    then:
+      # Historic bindings tied to the driver implementation
+      # The clocks provided here are meant to be matched with the input
+      # known (hard-coded) in the driver and used to select pwm clock
+      # source. Currently, the linux driver ignores this.
+      properties:
+        clock-names:
+          oneOf:
+            - items:
+                - enum: [clkin0, clkin1]
+            - items:
+                - const: clkin0
+                - const: clkin1
+
+  # Newer IP block take a single input per channel, instead of 4 inputs
+  # for both channels
+  - if:
+      properties:
+        compatible:
+          contains:
+            enum:
+              - amlogic,meson-s4-pwm
+    then:
+      properties:
+        clocks:
+          items:
+            - description: input clock of PWM channel A
+            - description: input clock of PWM channel B
+        clock-names: false
+      required:
+        - clocks
+
 additionalProperties: false
 
 examples:
@@ -68,3 +112,10 @@ examples:
       clock-names = "clkin0", "clkin1";
       #pwm-cells = <3>;
     };
+  - |
+    pwm@...0 {
+      compatible = "amlogic,meson-s4-pwm";
+      reg = <0x1000 0x10>;
+      clocks = <&pwm_src_a>, <&pwm_src_b>;
+      #pwm-cells = <3>;
+    };
-- 
2.42.0