dt-bindings: interrupt-controller: arm,gic-v3: Add dma-noncoherent property

The GIC v3 specifications allow redistributors and ITSes interconnect
ports used to access memory to be wired up in a way that makes the
respective initiators/memory observers non-coherent.

Add the standard dma-noncoherent property to the GICv3 bindings to
allow firmware to describe the redistributors/ITSes components and
interconnect ports behaviour in system designs where the redistributors
and ITSes are not coherent with the CPU.

Reviewed-by: Rob Herring <[email protected]>
Signed-off-by: Lorenzo Pieralisi <[email protected]>
Cc: Rob Herring <[email protected]>
Signed-off-by: Marc Zyngier <[email protected]>
Link: https://lore.kernel.org/r/[email protected]

Author: Lorenzo Pieralisi

Documentation/devicetree/bindings/interrupt-controller/arm,gic-v3.yaml

@@ -106,6 +106,12 @@ properties:
     $ref: /schemas/types.yaml#/definitions/uint32
     maximum: 4096
 
+  dma-noncoherent:
+    description:
+      Present if the GIC redistributors permit programming shareability
+      and cacheability attributes but are connected to a non-coherent
+      downstream interconnect.
+
   msi-controller:
     description:
       Only present if the Message Based Interrupt functionality is
@@ -193,6 +199,12 @@ patternProperties:
       compatible:
         const: arm,gic-v3-its
 
+      dma-noncoherent:
+        description:
+          Present if the GIC ITS permits programming shareability and
+          cacheability attributes but is connected to a non-coherent
+          downstream interconnect.
+
       msi-controller: true
 
       "#msi-cells":