Add binding to specify Spread Spectrum Clocking mode used.

Signed-off-by: Swapnil Jakhade <redacted>
---
 .../devicetree/bindings/phy/phy-cadence-sierra.yaml      | 9 +++++++++
 include/dt-bindings/phy/phy-cadence.h                    | 4 ++++
 2 files changed, 13 insertions(+)

diff --git a/Documentation/devicetree/bindings/phy/phy-cadence-sierra.yaml b/Documentation/devicetree/bindings/phy/phy-cadence-sierra.yaml
index e71b32c9c0d1..a9e227d8b076 100644
--- a/Documentation/devicetree/bindings/phy/phy-cadence-sierra.yaml
+++ b/Documentation/devicetree/bindings/phy/phy-cadence-sierra.yaml

@@ -113,6 +113,15 @@ patternProperties:
         minimum: 1
         maximum: 16
 
+      cdns,ssc-mode:
+        description:
+          Specifies the Spread Spectrum Clocking mode used. It can be NO_SSC,
+          EXTERNAL_SSC or INTERNAL_SSC.
+          Refer include/dt-bindings/phy/phy-cadence.h for the constants to be used.
+        $ref: /schemas/types.yaml#/definitions/uint32
+        enum: [0, 1, 2]
+        default: 1
+
     required:
       - reg
       - resets

diff --git a/include/dt-bindings/phy/phy-cadence.h b/include/dt-bindings/phy/phy-cadence.h
index 4652bcb86265..0122c6067b17 100644
--- a/include/dt-bindings/phy/phy-cadence.h
+++ b/include/dt-bindings/phy/phy-cadence.h

@@ -17,4 +17,8 @@
 #define CDNS_SIERRA_PLL_CMNLC		0
 #define CDNS_SIERRA_PLL_CMNLC1		1
 
+#define SIERRA_SERDES_NO_SSC		0
+#define SIERRA_SERDES_EXTERNAL_SSC	1
+#define SIERRA_SERDES_INTERNAL_SSC	2