From: Tzuyi Chang <redacted>

Add a generic pin configuration property
"input-threshold-voltage-microvolt" to support hardware designs where the
input logic threshold is decoupled from the power supply voltage.

This property allows the pinctrl driver to configure the correct internal
reference voltage for pins that need to accept input signals at a different
voltage level than their power supply. For example, a pin powered by 3.3V
may need to accept 1.8V logic signals.

This defines the reference for VIH (Input High Voltage) and VIL (Input Low
Voltage) thresholds, enabling proper signal detection across different
voltage domains.

Signed-off-by: Tzuyi Chang <redacted>
Co-developed-by: Yu-Chun Lin <eleanor.lin@realtek.com>
Signed-off-by: Yu-Chun Lin <eleanor.lin@realtek.com>
---
Changes in v4:
- Rename the property to input-threshold-voltage-microvolt.
- Add the restriction.
---
 Documentation/devicetree/bindings/pinctrl/pincfg-node.yaml | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/Documentation/devicetree/bindings/pinctrl/pincfg-node.yaml b/Documentation/devicetree/bindings/pinctrl/pincfg-node.yaml
index fe936ab09104..ecddb415c06f 100644
--- a/Documentation/devicetree/bindings/pinctrl/pincfg-node.yaml
+++ b/Documentation/devicetree/bindings/pinctrl/pincfg-node.yaml

@@ -162,6 +162,11 @@ properties:
       this affects the expected delay in ps before latching a value to
       an output pin.
 
+  input-threshold-voltage-microvolt:
+    description: Specifies the input voltage level of the pin in microvolts.
+      This defines the reference for  VIH (Input High Voltage) and VIL
+      (Input Low Voltage) thresholds for proper signal detection.
+
 allOf:
   - if:
       required:

@@ -177,6 +182,7 @@ allOf:
     then:
       properties:
         input-enable: false
+        input-threshold-voltage-microvolt: false
 
   - if:
       required:

-- 
2.34.1