[PATCH v4 11/12] dt-bindings: pinctrl: stm32: Support I/O synchronization parameters

Antonio Borneo
2025-10-23T13:27:39Z

Document the support of the I/O synchronization parameters:
- skew-delay-input-ps;
- skew-delay-output-ps;
- st,io-sync.

Forbid 'skew-delay-input-ps' and 'skew-delay-output-ps' to be both
present on the same pin.
Allow the new properties only with compatibles that support them.
Add an example that uses the new properties.

Co-developed-by: Fabien Dessenne <fabien.dessenne@foss.st.com>
Signed-off-by: Fabien Dessenne <fabien.dessenne@foss.st.com>
Signed-off-by: Antonio Borneo <antonio.borneo@foss.st.com>
---
.../bindings/pinctrl/st,stm32-pinctrl.yaml | 74 +++++++++++++++++++
1 file changed, 74 insertions(+)

diff --git a/Documentation/devicetree/bindings/pinctrl/st,stm32-pinctrl.yaml b/Documentation/devicetree/bindings/pinctrl/st,stm32-pinctrl.yaml
index 27c0dd7a8df01..76d956b4a5372 100644
--- a/Documentation/devicetree/bindings/pinctrl/st,stm32-pinctrl.yaml
+++ b/Documentation/devicetree/bindings/pinctrl/st,stm32-pinctrl.yaml
@@ -220,12 +220,65 @@ patternProperties:
minimum: 0
maximum: 3

+ skew-delay-input-ps:
+ description: |
+ IO synchronization skew rate applied to the input path
+ enum: [0, 300, 500, 750, 1000, 1250, 1500, 1750, 2000, 2250, 2500, 2750, 3000, 3250]
+
+ skew-delay-output-ps:
+ description: |
+ IO synchronization latch delay applied to the output path
+ enum: [0, 300, 500, 750, 1000, 1250, 1500, 1750, 2000, 2250, 2500, 2750, 3000, 3250]
+
+ st,io-sync:
+ $ref: /schemas/types.yaml#/definitions/string
+ enum:
+ - pass-through
+ - clock inverted
+ - data on rising edge
+ - data on falling edge
+ - data on both edges
+ description: |
+ IO synchronization through re-sampling or inversion
+ "pass-through" - data or clock GPIO pass-through
+ "clock inverted" - clock GPIO inverted
+ "data on rising edge" - data GPIO re-sampled on clock rising edge
+ "data on falling edge" - data GPIO re-sampled on clock falling edge
+ "data on both edges" - data GPIO re-sampled on both clock edges
+ default: pass-through
+
required:
- pinmux

+ # Not allowed both skew-delay-input-ps and skew-delay-output-ps
+ if:
+ required:
+ - skew-delay-input-ps
+ then:
+ properties:
+ skew-delay-output-ps: false
+
allOf:
- $ref: pinctrl.yaml#

+ - if:
+ not:
+ properties:
+ compatible:
+ contains:
+ enum:
+ - st,stm32mp257-pinctrl
+ - st,stm32mp257-z-pinctrl
+ then:
+ patternProperties:
+ '-[0-9]*$':
+ patternProperties:
+ '^pins':
+ properties:
+ skew-delay-input-ps: false
+ skew-delay-output-ps: false
+ st,io-sync: false
+
required:
- compatible
- '#address-cells'
@@ -306,4 +359,25 @@ examples:
pinctrl-names = "default";
};

+ - |
+ #include <dt-bindings/pinctrl/stm32-pinfunc.h>
+ //Example 4 skew-delay and st,io-sync
+ pinctrl: pinctrl@44240000 {
+ compatible = "st,stm32mp257-pinctrl";
+ #address-cells = <1>;
+ #size-cells = <1>;
+ ranges = <0 0x44240000 0xa0400>;
+
+ eth3_rgmii_pins_a: eth3-rgmii-0 {
+ pins1 {
+ pinmux = <STM32_PINMUX('A', 6, AF14)>;
+ st,io-sync = "data on both edges";
+ };
+ pins2 {
+ pinmux = <STM32_PINMUX('H', 2, AF14)>;
+ skew-delay-output-ps = <500>;
+ };
+ };
+ };
+
...
--
2.34.1