[PATCH V3 4/6] dt-bindings: dma: xlnx,zynqmp-dma: Add Versal Net compatible support

From: Jay Buddhabhatti <[email protected]>

Introduce a new compatible string amd,versal-net-dma-1.0 for
Versal Net ZDMA.The new compatible requires xlnx,zynqmp-dma-1.0 as a
fallback.

Add a reset property to describe the per-channel reset line exposed
on Versal Gen2 and Versal Net. Mark the resets property as required
for both Versal Gen2 and Versal Net, and not applicable for other
platforms.

Note that making resets required for Versal Gen2 results in an ABI
break but this is unavoidable. When DMA is used by two software components
back to back (e.g., firmware before Linux boot), DMA functionality fails
due to configuration differences or the DMA being left in a bad state by
the previous user. The channel can only be cleanly re-configured after
a DMA channel reset,making it essential.

Signed-off-by: Jay Buddhabhatti <[email protected]>
Co-developed-by: Golla Nagendra <[email protected]>
Signed-off-by: Golla Nagendra <[email protected]>
---
Changes in V3:
- Use allOf:if:then: to restrict the resets property per-compatible,
  making it required for amd,versal2-dma-1.0 and amd,versal-net-dma-1.0
  and explicitly setting resets: false for all other platforms
- Add amd,versal-net-dma-1.0 compatible string with xlnx,zynqmp-dma-1.0
  as fallback
- Switch compatible from enum to oneOf to accommodate the new multi-item
  entry for Versal Net
- Add ABI break justification
---
 .../dma/xilinx/xlnx,zynqmp-dma-1.0.yaml       | 25 ++++++++++++++++---
 1 file changed, 22 insertions(+), 3 deletions(-)

diff --git a/Documentation/devicetree/bindings/dma/xilinx/xlnx,zynqmp-dma-1.0.yaml b/Documentation/devicetree/bindings/dma/xilinx/xlnx,zynqmp-dma-1.0.yaml
index 2da86037ad79..87c65aef5c7d 100644
--- a/Documentation/devicetree/bindings/dma/xilinx/xlnx,zynqmp-dma-1.0.yaml
+++ b/Documentation/devicetree/bindings/dma/xilinx/xlnx,zynqmp-dma-1.0.yaml
@@ -18,15 +18,31 @@ maintainers:
 
 allOf:
   - $ref: ../dma-controller.yaml#
+  - if:
+      properties:
+        compatible:
+          contains:
+            enum:
+              - amd,versal2-dma-1.0
+              - amd,versal-net-dma-1.0
+    then:
+      required:
+        - resets
+    else:
+      properties:
+        resets: false
 
 properties:
   "#dma-cells":
     const: 1
 
   compatible:
-    enum:
-      - amd,versal2-dma-1.0
-      - xlnx,zynqmp-dma-1.0
+    oneOf:
+      - const: amd,versal2-dma-1.0
+      - const: xlnx,zynqmp-dma-1.0
+      - items:
+          - const: amd,versal-net-dma-1.0
+          - const: xlnx,zynqmp-dma-1.0
 
   reg:
     description: memory map for gdma/adma module access
@@ -59,6 +75,9 @@ properties:
   power-domains:
     maxItems: 1
 
+  resets:
+    maxItems: 1
+
   dma-coherent: true
 
 required:
-- 
2.43.7