[PATCH 0/3] Add T7 PWM core clock support

[PATCH 0/3] Add T7 PWM core clock support

[Ronald Claveau via B4 Relay]

The PWM controllers on the Amlogic T7 SoC have a system clock that
controls access to the controller, in addition to the two input
clocks of channels A and B.

It is currently not described in the device tree, so it is neither
referenced nor enabled by the driver.

This series adds support for it:

  - patch 1 extends the binding with a third "core" clock for
    amlogic,t7-pwm, and makes clocks/clock-names required for it;
  - patch 2 makes the driver get and enable the optional "core"
    clock, leaving other SoCs unaffected;
  - patch 3 describes the system clock (CLKID_SYS_PWM_*) in the T7
    device tree for all the PWM controllers.

`dt_binding_check DT_SCHEMA_FILES=pwm-amlogic.yaml` test is ok

  CHKDT   ./Documentation/devicetree/bindings
warning: python package 'yamllint' not installed, skipping
  STYLE   ./Documentation/devicetree/bindings
  DTEX    Documentation/devicetree/bindings/pwm/pwm-amlogic.example.dts
  DTC [C] Documentation/devicetree/bindings/pwm/pwm-amlogic.example.dtb

Signed-off-by: Ronald Claveau <linux-kernel-dev@aliel.fr>
---
Ronald Claveau (3):
      dt-bindings: pwm: amlogic: Add core clock for T7
      pwm: meson: Add optional core clock for S4 PWM
      arm64: dts: amlogic: t7: Add core clock to PWM controller nodes

 .../devicetree/bindings/pwm/pwm-amlogic.yaml       | 37 +++++++++++++++++++---
 arch/arm64/boot/dts/amlogic/amlogic-t7.dtsi        | 28 ++++++++++++----
 drivers/pwm/pwm-meson.c                            |  5 +++
 3 files changed, 59 insertions(+), 11 deletions(-)
---
base-commit: a8c591ed6b672915e0be57843f943a2a723aff40
change-id: 20260924-add-t7-sys-pwm-clk-f0eff81bee21

Best regards,
-- 
Ronald Claveau <linux-kernel-dev@aliel.fr>



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[PATCH 1/3] dt-bindings: pwm: amlogic: Add core clock for T7

[Ronald Claveau via B4 Relay]

From: Ronald Claveau <linux-kernel-dev@aliel.fr>

The T7 PWM controller has a system clock (the register access clock)
in addition to the two input clocks of channels A and B. Add it as a
third clock, named "core", for the amlogic,t7-pwm compatible, and
require clock-names for this SoC for clarity.

The other compatibles are left unchanged. Add an example showing the
T7 usage with its fallback to amlogic,meson-s4-pwm.

Signed-off-by: Ronald Claveau <linux-kernel-dev@aliel.fr>
---
 .../devicetree/bindings/pwm/pwm-amlogic.yaml       | 37 +++++++++++++++++++---
 1 file changed, 33 insertions(+), 4 deletions(-)

diff --git a/Documentation/devicetree/bindings/pwm/pwm-amlogic.yaml b/Documentation/devicetree/bindings/pwm/pwm-amlogic.yaml
index c337d85da40f1..9212a40d9fe48 100644
--- a/Documentation/devicetree/bindings/pwm/pwm-amlogic.yaml
+++ b/Documentation/devicetree/bindings/pwm/pwm-amlogic.yaml
@@ -62,7 +62,7 @@ properties:
 
   clock-names:
     minItems: 1
-    maxItems: 2
+    maxItems: 3
 
   power-domains:
     maxItems: 1
@@ -135,17 +135,38 @@ allOf:
       properties:
         compatible:
           contains:
-            enum:
-              - amlogic,meson-s4-pwm
+            const: amlogic,t7-pwm
     then:
       properties:
         clocks:
           items:
             - description: input clock of PWM channel A
             - description: input clock of PWM channel B
-        clock-names: false
+            - description: gate clock for the PWM controller
+        clock-names:
+          items:
+            - const: clk_a
+            - const: clk_b
+            - const: core
       required:
         - clocks
+        - clock-names
+    else:
+      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
 
   - if:
       properties:
@@ -182,3 +203,11 @@ examples:
       clocks = <&pwm_src_a>, <&pwm_src_b>;
       #pwm-cells = <3>;
     };
+  - |
+    pwm@60000 {
+      compatible = "amlogic,t7-pwm", "amlogic,meson-s4-pwm";
+      reg = <0x60000 0x24>;
+      clocks = <&clk_a>, <&clk_b>, <&core>;
+      clock-names = "clk_a", "clk_b", "core";
+      #pwm-cells = <3>;
+    };

-- 
2.49.0



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[PATCH 2/3] pwm: meson: Add optional core clock for S4 PWM

[Ronald Claveau via B4 Relay]

From: Ronald Claveau <linux-kernel-dev@aliel.fr>

On some SoCs (e.g. T7), the PWM controller has a system clock that must
be enabled to access its registers, in addition to the per-channel
input clocks.

Get and enable it with devm_clk_get_optional_enabled() using the
"core" name. The clock is optional, so existing SoCs and device trees
that do not provide it keep working unchanged.

Signed-off-by: Ronald Claveau <linux-kernel-dev@aliel.fr>
---
 drivers/pwm/pwm-meson.c | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/drivers/pwm/pwm-meson.c b/drivers/pwm/pwm-meson.c
index 20e6cd07127c4..5ab07322e8d15 100644
--- a/drivers/pwm/pwm-meson.c
+++ b/drivers/pwm/pwm-meson.c
@@ -508,8 +508,13 @@ static int meson_pwm_init_channels_s4(struct pwm_chip *chip)
 	struct device *dev = pwmchip_parent(chip);
 	struct device_node *np = dev->of_node;
 	struct meson_pwm *meson = to_meson_pwm(chip);
+	struct clk *core_clk;
 	int i, ret;
 
+	core_clk = devm_clk_get_optional_enabled(dev, "core");
+	if (IS_ERR(core_clk))
+		return dev_err_probe(dev, PTR_ERR(core_clk), "Failed to get core clock\n");
+
 	for (i = 0; i < MESON_NUM_PWMS; i++) {
 		meson->channels[i].clk = of_clk_get(np, i);
 		if (IS_ERR(meson->channels[i].clk))

-- 
2.49.0



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[PATCH 3/3] arm64: dts: amlogic: t7: Add core clock to PWM controller nodes

[Ronald Claveau via B4 Relay]

From: Ronald Claveau <linux-kernel-dev@aliel.fr>

Describe the system clock of each PWM controller (CLKID_SYS_PWM_*) as a
third clock, and add the clock-names property expected by the updated
binding: "clk_a", "clk_b" and "core".

Signed-off-by: Ronald Claveau <linux-kernel-dev@aliel.fr>
---
 arch/arm64/boot/dts/amlogic/amlogic-t7.dtsi | 28 +++++++++++++++++++++-------
 1 file changed, 21 insertions(+), 7 deletions(-)

diff --git a/arch/arm64/boot/dts/amlogic/amlogic-t7.dtsi b/arch/arm64/boot/dts/amlogic/amlogic-t7.dtsi
index 8f3f1c0579a0f..83c597d418875 100644
--- a/arch/arm64/boot/dts/amlogic/amlogic-t7.dtsi
+++ b/arch/arm64/boot/dts/amlogic/amlogic-t7.dtsi
@@ -692,7 +692,9 @@ pwm_ao_ef: pwm@30000 {
 				compatible = "amlogic,t7-pwm", "amlogic,meson-s4-pwm";
 				reg = <0x0 0x30000 0x0 0x24>;
 				clocks = <&clkc_periphs CLKID_PWM_AO_E>,
-					 <&clkc_periphs CLKID_PWM_AO_F>;
+					 <&clkc_periphs CLKID_PWM_AO_F>,
+					 <&clkc_periphs CLKID_SYS_PWM_AO_EF>;
+				clock-names = "clk_a", "clk_b", "core";
 				#pwm-cells = <3>;
 				status = "disabled";
 			};
@@ -701,7 +703,9 @@ pwm_ao_gh: pwm@32000 {
 				compatible = "amlogic,t7-pwm", "amlogic,meson-s4-pwm";
 				reg = <0x0 0x32000 0x0 0x24>;
 				clocks = <&clkc_periphs CLKID_PWM_AO_G>,
-					 <&clkc_periphs CLKID_PWM_AO_H>;
+					 <&clkc_periphs CLKID_PWM_AO_H>,
+					 <&clkc_periphs CLKID_SYS_PWM_AO_GH>;
+				clock-names = "clk_a", "clk_b", "core";
 				#pwm-cells = <3>;
 				status = "disabled";
 			};
@@ -715,7 +719,9 @@ pwm_ab: pwm@58000 {
 				compatible = "amlogic,t7-pwm", "amlogic,meson-s4-pwm";
 				reg = <0x0 0x58000 0x0 0x24>;
 				clocks = <&clkc_periphs CLKID_PWM_A>,
-					 <&clkc_periphs CLKID_PWM_B>;
+					 <&clkc_periphs CLKID_PWM_B>,
+					 <&clkc_periphs CLKID_SYS_PWM_AB>;
+				clock-names = "clk_a", "clk_b", "core";
 				#pwm-cells = <3>;
 				status = "disabled";
 			};
@@ -724,7 +730,9 @@ pwm_cd: pwm@5a000 {
 				compatible = "amlogic,t7-pwm", "amlogic,meson-s4-pwm";
 				reg = <0x0 0x5a000 0x0 0x24>;
 				clocks = <&clkc_periphs CLKID_PWM_C>,
-					 <&clkc_periphs CLKID_PWM_D>;
+					 <&clkc_periphs CLKID_PWM_D>,
+					 <&clkc_periphs CLKID_SYS_PWM_CD>;
+				clock-names = "clk_a", "clk_b", "core";
 				#pwm-cells = <3>;
 				status = "disabled";
 			};
@@ -733,7 +741,9 @@ pwm_ef: pwm@5c000 {
 				compatible = "amlogic,t7-pwm", "amlogic,meson-s4-pwm";
 				reg = <0x0 0x5c000 0x0 0x24>;
 				clocks = <&clkc_periphs CLKID_PWM_E>,
-					 <&clkc_periphs CLKID_PWM_F>;
+					 <&clkc_periphs CLKID_PWM_F>,
+					 <&clkc_periphs CLKID_SYS_PWM_EF>;
+				clock-names = "clk_a", "clk_b", "core";
 				#pwm-cells = <3>;
 				status = "disabled";
 			};
@@ -742,7 +752,9 @@ pwm_ao_ab: pwm@5e000 {
 				compatible = "amlogic,t7-pwm", "amlogic,meson-s4-pwm";
 				reg = <0x0 0x5e000 0x0 0x24>;
 				clocks = <&clkc_periphs CLKID_PWM_AO_A>,
-					 <&clkc_periphs CLKID_PWM_AO_B>;
+					 <&clkc_periphs CLKID_PWM_AO_B>,
+					 <&clkc_periphs CLKID_SYS_PWM_AO_AB>;
+				clock-names = "clk_a", "clk_b", "core";
 				#pwm-cells = <3>;
 				status = "disabled";
 			};
@@ -751,7 +763,9 @@ pwm_ao_cd: pwm@60000 {
 				compatible = "amlogic,t7-pwm", "amlogic,meson-s4-pwm";
 				reg = <0x0 0x60000 0x0 0x24>;
 				clocks = <&clkc_periphs CLKID_PWM_AO_C>,
-					 <&clkc_periphs CLKID_PWM_AO_D>;
+					 <&clkc_periphs CLKID_PWM_AO_D>,
+					 <&clkc_periphs CLKID_SYS_PWM_AO_CD>;
+				clock-names = "clk_a", "clk_b", "core";
 				#pwm-cells = <3>;
 				status = "disabled";
 			};

-- 
2.49.0



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Re: [PATCH 1/3] dt-bindings: pwm: amlogic: Add core clock for T7

[sashiko-bot]

Thank you for your contribution! Sashiko AI review found 1 potential issue(s) to consider:
- [Medium] dt-bindings: pwm: amlogic: ABI break for amlogic,t7-pwm
--

commit ea055f0ab3ecf76a41b2a2cf99ee615eac00cdc9
Author: Ronald Claveau <linux-kernel-dev@aliel.fr>

dt-bindings: pwm: amlogic: Add core clock for T7

This commit adds a third core clock for the amlogic,t7-pwm compatible
binding and requires clock-names for this SoC. Other compatibles are left
unchanged, and an example is added for T7 usage.

> diff --git a/Documentation/devicetree/bindings/pwm/pwm-amlogic.yaml b/Documentation/devicetree/bindings/pwm/pwm-amlogic.yaml
> index c337d85da40f1..9212a40d9fe48 100644
> --- a/Documentation/devicetree/bindings/pwm/pwm-amlogic.yaml
> +++ b/Documentation/devicetree/bindings/pwm/pwm-amlogic.yaml

[ ... ]

> @@ -135,17 +135,38 @@ allOf:
>        properties:
>          compatible:
>            contains:
> -            enum:
> -              - amlogic,meson-s4-pwm
> +            const: amlogic,t7-pwm
>      then:
>        properties:
>          clocks:
>            items:
>              - description: input clock of PWM channel A
>              - description: input clock of PWM channel B
> -        clock-names: false
> +            - description: gate clock for the PWM controller
> +        clock-names:
> +          items:
> +            - const: clk_a
> +            - const: clk_b
> +            - const: core
>        required:
>          - clocks
> +        - clock-names

[Severity: Medium]
Does this introduce a schema validation regression for older device trees?

By defining exactly three items in the clocks list and strictly requiring
the clock-names property, older device trees that only provide two clocks
and omit clock-names will fail validation. Device tree schemas typically
must maintain backward compatibility with older or out-of-tree DTBs.

Should the schema specify a minimum item count of 2 for clocks and only
conditionally require clock-names based on the number of clocks provided
to avoid an ABI break?

-- 
Sashiko AI review · https://sashiko.dev/#/patchset/20260924-add-t7-sys-pwm-clk-v1-0-05b91e87f0a9@aliel.fr?part=1

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