dt-bindings: connector: Add property to set initial current cap for FRS

This change adds frs-typec-current which allows setting the initial current
capability of the new source when vSafe5V is applied during PD3.0
sink Fast Role Swap.
Signed-off-by: Badhri Jagan Sridharan <badhri@google.com>
Reviewed-by: Rob Herring <robh@kernel.org>
Link: https://lore.kernel.org/r/20201020093627.256885-2-badhri@google.comSigned-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Documentation/devicetree/bindings/connector/usb-connector.yaml

@@ -147,6 +147,25 @@ properties:
     required:
       - port@0
 
+  new-source-frs-typec-current:
+    description: Initial current capability of the new source when vSafe5V
+      is applied during PD3.0 Fast Role Swap. "Table 6-14 Fixed Supply PDO - Sink"
+      of "USB Power Delivery Specification Revision 3.0, Version 1.2" provides the
+      different power levels and "6.4.1.3.1.6 Fast Role Swap USB Type-C Current"
+      provides a detailed description of the field. The sink PDO from current source
+      reflects the current source's(i.e. transmitter of the FRS signal) power
+      requirement during fr swap. The current sink (i.e. receiver of the FRS signal),
+      a.k.a new source, should check if it will be able to satisfy the current source's,
+      new sink's, requirement during frswap before enabling the frs signal reception.
+      This property refers to maximum current capability that the current sink can
+      satisfy. During FRS, VBUS voltage is at 5V, as the partners are in implicit
+      contract, hence, the power level is only a function of the current capability.
+      "1" refers to default USB power level as described by "Table 6-14 Fixed Supply PDO - Sink".
+      "2" refers to 1.5A@5V.
+      "3" refers to 3.0A@5V.
+    $ref: /schemas/types.yaml#/definitions/uint32
+    enum: [1, 2, 3]
+
 required:
   - compatible
 

include/dt-bindings/usb/pd.h

@@ -85,4 +85,12 @@
 	 PDO_PPS_APDO_MIN_VOLT(min_mv) | PDO_PPS_APDO_MAX_VOLT(max_mv) |	\
 	 PDO_PPS_APDO_MAX_CURR(max_ma))
 
+ /*
+  * Based on "Table 6-14 Fixed Supply PDO - Sink" of "USB Power Delivery Specification Revision 3.0,
+  * Version 1.2"
+  * Initial current capability of the new source when vSafe5V is applied.
+  */
+#define FRS_DEFAULT_POWER      1
+#define FRS_5V_1P5A            2
+#define FRS_5V_3A              3
  #endif /* __DT_POWER_DELIVERY_H */