[PATCH v2 8/9] dt-bindings: pinctrl: stm32: Support I/O synchronization parameters

[Antonio Borneo]

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

Require 'skew-delay-direction' when 'skew-delay' is non zero.
Allow the new properties only with compatibles that support them.
Add an example that uses all the new properties.

Co-developed-by: Fabien Dessenne <fabien.dessenne@xxxxxxxxxxx>
Signed-off-by: Fabien Dessenne <fabien.dessenne@xxxxxxxxxxx>
Signed-off-by: Antonio Borneo <antonio.borneo@xxxxxxxxxxx>
---
 .../bindings/pinctrl/st,stm32-pinctrl.yaml    | 92 +++++++++++++++++++
 1 file changed, 92 insertions(+)

diff --git a/Documentation/devicetree/bindings/pinctrl/st,stm32-pinctrl.yaml b/Documentation/devicetree/bindings/pinctrl/st,stm32-pinctrl.yaml
index 961161c2ab62b..d20669fd5d9c9 100644
--- a/Documentation/devicetree/bindings/pinctrl/st,stm32-pinctrl.yaml
+++ b/Documentation/devicetree/bindings/pinctrl/st,stm32-pinctrl.yaml
@@ -225,12 +225,82 @@ patternProperties:
             $ref: /schemas/types.yaml#/definitions/uint32
             enum: [0, 1, 2, 3]
 
+          skew-delay:
+            description: |
+              IO synchronization delay applied to the input or output path
+              depending on 'skew-delay-direction' property
+              0: No delay
+              1: Delay 0.30 ns
+              2: Delay 0.50 ns
+              3: Delay 0.75 ns
+              4: Delay 1.00 ns
+              5: Delay 1.25 ns
+              6: Delay 1.50 ns
+              7: Delay 1.75 ns
+              8: Delay 2.00 ns
+              9: Delay 2.25 ns
+              10: Delay 2.50 ns
+              11: Delay 2.75 ns
+              12: Delay 3.00 ns
+              13: Delay 3.25 ns
+            minimum: 0
+            maximum: 13
+            default: 0
+
+          skew-delay-direction:
+            description: |
+              IO synchronization delay path location
+              1: Delay on the output path
+              2: Delay on the input path
+            $ref: /schemas/types.yaml#/definitions/uint32
+            enum: [1, 2]
+
+          st,io-sync:
+            description: |
+              IO synchronization through re-sampling or inversion
+              0: data or clock GPIO pass-through
+              1: clock GPIO inverted
+              2: data GPIO re-sampled on clock rising edge
+              3: data GPIO re-sampled on clock falling edge
+              4: data GPIO re-sampled on both clock edges
+            $ref: /schemas/types.yaml#/definitions/uint32
+            enum: [0, 1, 2, 3, 4]
+            default: 0
+
         required:
           - pinmux
 
+        allOf:
+          - if:
+              not:
+                properties:
+                  skew-delay:
+                    const: 0
+            then:
+              required:
+                - skew-delay-direction
+
 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: false
+                skew-delay-direction: false
+                st,io-sync: false
+
 required:
   - compatible
   - '#address-cells'
@@ -311,4 +381,26 @@ 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 = <4>;
+                      };
+                      pins2 {
+                              pinmux = <STM32_PINMUX('H', 2, AF14)>;
+                              skew-delay = <2>;
+                              skew-delay-direction = <1>;
+                      };
+              };
+      };
+
 ...
-- 
2.34.1