[PATCH v5] dt-bindings: pwm: st,sti-pwm: convert to DT schema

[PATCH v5] dt-bindings: pwm: st,sti-pwm: convert to DT schema

[Charan Pedumuru]

Convert STMicroelectronics STiH41x PWM/Capture controller binding
to DT schema.
Changes during conversion:
- Fix compatible string from "st,pwm" to "st,sti-pwm" to match the
  actual hardware variant naming convention used across STi bindings.
- Drop pinctrl-names from the required list as pinctrl properties are
  inherited and validated by the pinctrl schema.

Signed-off-by: Charan Pedumuru <charan.pedumuru@gmail.com>
---
Changes in v5:
- Enforce stricter validation of the clock-names property.
- Link to v4: https://patch.msgid.link/20260625-st-pwm-v4-1-958d7d6bdf39@gmail.com

Changes in v4:
- Fix compatible to "st,sti-pwm" in examples.
- Modify subject line to point to the correct YAML file.
- Link to v3: https://patch.msgid.link/20260625-st-pwm-v3-1-ace9bff88529@gmail.com

Changes in v3:
- Fix compatible to "st,sti-pwm".
- Drop pinctrl-names from required.
- Modify the commit message to explain the changes made.
- Change maintainer to "Lee Jones <lee.jones@linaro.org>".
- Link to v2: https://patch.msgid.link/20260618-st-pwm-v2-1-c792d5795ce2@gmail.com

Changes in v2:
- Add the missing interrupts to the required following the old binding.
- Modify the commit message to explain the changes made.
- Link to v1: https://patch.msgid.link/20260613-st-pwm-v1-1-458c2c89709a@gmail.com
---
 Documentation/devicetree/bindings/pwm/pwm-st.txt   | 43 ----------
 .../devicetree/bindings/pwm/st,sti-pwm.yaml        | 92 ++++++++++++++++++++++
 2 files changed, 92 insertions(+), 43 deletions(-)

diff --git a/Documentation/devicetree/bindings/pwm/pwm-st.txt b/Documentation/devicetree/bindings/pwm/pwm-st.txt
deleted file mode 100644
index 19fce774cafa..000000000000
--- a/Documentation/devicetree/bindings/pwm/pwm-st.txt
+++ /dev/null
@@ -1,43 +0,0 @@
-STMicroelectronics PWM driver bindings
---------------------------------------
-
-Required parameters:
-- compatible :		"st,pwm"
-- #pwm-cells : 		Number of cells used to specify a PWM. First cell
-			specifies the per-chip index of the PWM to use and the
-			second cell is the period in nanoseconds - fixed to 2
-			for STiH41x.
-- reg :			Physical base address and length of the controller's
-			registers.
-- pinctrl-names: 	Set to "default".
-- pinctrl-0: 		List of phandles pointing to pin configuration nodes
-			for PWM module.
-			For Pinctrl properties, please refer to [1].
-- clock-names: 		Valid entries are "pwm" and/or "capture".
-- clocks: 		phandle of the clock used by the PWM module.
-			For Clk properties, please refer to [2].
-- interrupts:		IRQ for the Capture device
-
-Optional properties:
-- st,pwm-num-chan:	Number of available PWM channels.  Default is 0.
-- st,capture-num-chan:	Number of available Capture channels.  Default is 0.
-
-[1] Documentation/devicetree/bindings/pinctrl/pinctrl-bindings.txt
-[2] Documentation/devicetree/bindings/clock/clock-bindings.txt
-
-Example:
-
-pwm1: pwm@fe510000 {
-	compatible = "st,pwm";
-	reg = <0xfe510000 0x68>;
-	#pwm-cells = <2>;
-	pinctrl-names = "default";
-	pinctrl-0 = <&pinctrl_pwm1_chan0_default
-		     &pinctrl_pwm1_chan1_default
-		     &pinctrl_pwm1_chan2_default
-		     &pinctrl_pwm1_chan3_default>;
-	clocks = <&clk_sysin>;
-	clock-names = "pwm";
-	st,pwm-num-chan = <4>;
-	st,capture-num-chan = <2>;
-};
diff --git a/Documentation/devicetree/bindings/pwm/st,sti-pwm.yaml b/Documentation/devicetree/bindings/pwm/st,sti-pwm.yaml
new file mode 100644
index 000000000000..39f96596c1ef
--- /dev/null
+++ b/Documentation/devicetree/bindings/pwm/st,sti-pwm.yaml
@@ -0,0 +1,92 @@
+# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
+%YAML 1.2
+---
+$id: http://devicetree.org/schemas/pwm/st,sti-pwm.yaml#
+$schema: http://devicetree.org/meta-schemas/core.yaml#
+
+title: STMicroelectronics STiH41x PWM/Capture controller
+
+maintainers:
+  - Lee Jones <lee.jones@linaro.org>
+
+description:
+  The STiH41x PWM controller supports both PWM output and input capture
+  functionality. It provides multiple PWM output channels for generating
+  variable duty-cycle waveforms, and multiple input capture channels for
+  measuring external signal periods and pulse widths. PWM output channels
+  and input capture channels are configured independently via
+  st,pwm-num-chan and st,capture-num-chan respectively.
+
+allOf:
+  - $ref: pwm.yaml#
+
+properties:
+  compatible:
+    const: st,sti-pwm
+
+  reg:
+    maxItems: 1
+
+  "#pwm-cells":
+    const: 2
+
+  pinctrl-names:
+    const: default
+
+  clock-names:
+    minItems: 1
+    items:
+      - const: pwm
+      - const: capture
+
+  clocks:
+    minItems: 1
+    maxItems: 2
+
+  interrupts:
+    description: IRQ line for the capture device.
+    maxItems: 1
+
+  st,pwm-num-chan:
+    $ref: /schemas/types.yaml#/definitions/uint32
+    description: Number of available PWM output channels.
+    minimum: 0
+    maximum: 4
+    default: 0
+
+  st,capture-num-chan:
+    $ref: /schemas/types.yaml#/definitions/uint32
+    description: Number of available input capture channels.
+    minimum: 0
+    maximum: 4
+    default: 0
+
+required:
+  - reg
+  - compatible
+  - "#pwm-cells"
+  - clock-names
+  - clocks
+  - interrupts
+
+unevaluatedProperties: false
+
+examples:
+  - |
+    #include <dt-bindings/interrupt-controller/arm-gic.h>
+    pwm@fe510000 {
+        compatible = "st,sti-pwm";
+        reg = <0xfe510000 0x68>;
+        interrupts = <GIC_SPI 128 IRQ_TYPE_LEVEL_HIGH>;
+        #pwm-cells = <2>;
+        pinctrl-names = "default";
+        pinctrl-0 = <&pinctrl_pwm1_chan0_default
+                     &pinctrl_pwm1_chan1_default
+                     &pinctrl_pwm1_chan2_default
+                     &pinctrl_pwm1_chan3_default>;
+        clocks = <&clk_sysin>;
+        clock-names = "pwm";
+        st,pwm-num-chan = <4>;
+        st,capture-num-chan = <2>;
+    };
+...

---
base-commit: c425609d6ac4012c8bbf01ec2e10e801b1923a7b
change-id: 20260613-st-pwm-1feade6cfea3

Best regards,
--  
Charan Pedumuru <charan.pedumuru@gmail.com>

Re: [PATCH v5] dt-bindings: pwm: st,sti-pwm: convert to DT schema

[sashiko-bot]

Thank you for your contribution! Sashiko AI review found 1 potential issue(s) to consider:
- [Medium] The `clock-names` YAML schema strictly enforces an ordered list starting with `"pwm"`, which improperly rejects valid capture-only configurations.
--

commit c9b4fd6ce8e4e0ebe419750b4c65554ab14080bc
Author: Charan Pedumuru <charan.pedumuru@gmail.com>

dt-bindings: pwm: st,sti-pwm: convert to DT schema

This commit converts the STMicroelectronics STiH41x PWM/Capture controller
binding from a text file to DT schema. It updates the compatible string to
match hardware conventions and drops inherited pinctrl properties from the
required list.

> diff --git a/Documentation/devicetree/bindings/pwm/st,sti-pwm.yaml b/Documentation/devicetree/bindings/pwm/st,sti-pwm.yaml
> new file mode 100644
> index 0000000000000..39f96596c1ef8
> --- /dev/null
> +++ b/Documentation/devicetree/bindings/pwm/st,sti-pwm.yaml

[ ... ]

> +  pinctrl-names:
> +    const: default
> +
> +  clock-names:
> +    minItems: 1
> +    items:
> +      - const: pwm
> +      - const: capture

[Severity: Medium]
Can this rigid sequence for clock-names improperly reject valid capture-only
configurations during schema validation?

The driver selectively fetches clocks based on whether st,pwm-num-chan and
st,capture-num-chan are non-zero. If a hardware variant is configured solely
for input capture, it only needs the "capture" clock.

By defining an items array that starts with a constant of "pwm", the schema
mandates that the first or only clock name must be "pwm". Consequently, a
valid single-clock configuration providing just "capture" will be rejected by
the validation tools.

Would it make sense to use a more flexible schema construct like enum, anyOf,
or oneOf to allow either clock to be specified independently?

> +
> +  clocks:
> +    minItems: 1
> +    maxItems: 2

-- 
Sashiko AI review · https://sashiko.dev/#/patchset/20260629-st-pwm-v5-1-a93f2bfec38c@gmail.com?part=1

Re: [PATCH v5] dt-bindings: pwm: st,sti-pwm: convert to DT schema

[Krzysztof Kozlowski]

On Mon, Jun 29, 2026 at 12:58:37PM +0000, Charan Pedumuru wrote:
> Convert STMicroelectronics STiH41x PWM/Capture controller binding
> to DT schema.
> Changes during conversion:
> - Fix compatible string from "st,pwm" to "st,sti-pwm" to match the
>   actual hardware variant naming convention used across STi bindings.
> - Drop pinctrl-names from the required list as pinctrl properties are
>   inherited and validated by the pinctrl schema.

Reviewed-by: Krzysztof Kozlowski <krzysztof.kozlowski@oss.qualcomm.com>

Best regards,
Krzysztof