linux-kernel - [PATCH 2/3] dt-bindings: pwm: adi,axi-pwmgen: add external clock

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Message-Id: <20250520-pwm-axi-pwmgen-add-external-clock-v1-2-6cd63cc001c8@baylibre.com>
Date: Tue, 20 May 2025 16:00:45 -0500
From: David Lechner <dlechner@...libre.com>
To: Michael Hennerich <michael.hennerich@...log.com>, 
 Nuno Sá <nuno.sa@...log.com>, 
 Trevor Gamblin <tgamblin@...libre.com>, 
 Uwe Kleine-König <ukleinek@...nel.org>, 
 Rob Herring <robh@...nel.org>, Krzysztof Kozlowski <krzk+dt@...nel.org>, 
 Conor Dooley <conor+dt@...nel.org>
Cc: linux-pwm@...r.kernel.org, devicetree@...r.kernel.org, 
 linux-kernel@...r.kernel.org, David Lechner <dlechner@...libre.com>
Subject: [PATCH 2/3] dt-bindings: pwm: adi,axi-pwmgen: add external clock

Add external clock to the schema.

The AXI PWMGEN IP block has a compile option ASYNC_CLK_EN that allows
the use of an external clock for the PWM output separate from the AXI
clock that runs the peripheral.

In these cases, we should specify both clocks in the device tree. The
intention here is that if you specify both clocks, then you include the
clock-names property and if you don't have an external clock, then you
omit the clock-names property.

There can't be more than one allOf: in the top level of the schema, so
it is stolen from $ref since it isn't needed there and used for the
more typical case of the if statement (even though technically it isn't
needed there either at this time).

Signed-off-by: David Lechner <dlechner@...libre.com>
---
 .../devicetree/bindings/pwm/adi,axi-pwmgen.yaml    | 26 ++++++++++++++++++----
 1 file changed, 22 insertions(+), 4 deletions(-)

diff --git a/Documentation/devicetree/bindings/pwm/adi,axi-pwmgen.yaml b/Documentation/devicetree/bindings/pwm/adi,axi-pwmgen.yaml
index bc44381692054f647a160a6573dae4cff2ee3f31..90f702a5cd80bd7d62e2436b2eed44314ab4fd53 100644
--- a/Documentation/devicetree/bindings/pwm/adi,axi-pwmgen.yaml
+++ b/Documentation/devicetree/bindings/pwm/adi,axi-pwmgen.yaml
@@ -16,8 +16,7 @@ description:
 
   https://analogdevicesinc.github.io/hdl/library/axi_pwm_gen/index.html
 
-allOf:
-  - $ref: pwm.yaml#
+$ref: pwm.yaml#
 
 properties:
   compatible:
@@ -30,7 +29,13 @@ properties:
     const: 3
 
   clocks:
-    maxItems: 1
+    minItems: 1
+    maxItems: 2
+
+  clock-names:
+    items:
+      - const: axi
+      - const: ext
 
 required:
   - reg
@@ -38,11 +43,24 @@ required:
 
 unevaluatedProperties: false
 
+allOf:
+  - if:
+      required: [clock-names]
+    then:
+      properties:
+        clocks:
+          minItems: 2
+    else:
+      properties:
+        clocks:
+          maxItems: 1
+
 examples:
   - |
     pwm@...00000 {
         compatible = "adi,axi-pwmgen-2.00.a";
         reg = <0x44b00000 0x1000>;
-        clocks = <&spi_clk>;
+        clocks = <&fpga_clk>, <&spi_clk>;
+        clock-names = "axi", "ext";
         #pwm-cells = <3>;
     };

-- 
2.43.0