[PATCH v2 2/2] dt-bindings: mfd: syscon: Add support for regmap fast-io

[AngeloGioacchino Del Regno]

The syscon driver now enables the .fast_io regmap configuration when
the 'fast-io' property is found in a syscon node.

Keeping in mind that, in regmap, fast_io is checked only if we are
not using hardware spinlocks, allow the fast-io property only if
there is no hwlocks reference (and vice-versa).

Signed-off-by: AngeloGioacchino Del Regno <angelogioacchino.delregno@xxxxxxxxxxxxx>
---
 Documentation/devicetree/bindings/mfd/syscon.yaml | 15 +++++++++++++++
 1 file changed, 15 insertions(+)

diff --git a/Documentation/devicetree/bindings/mfd/syscon.yaml b/Documentation/devicetree/bindings/mfd/syscon.yaml
index 13baa452cc9d..621b0983b115 100644
--- a/Documentation/devicetree/bindings/mfd/syscon.yaml
+++ b/Documentation/devicetree/bindings/mfd/syscon.yaml
@@ -83,11 +83,26 @@ properties:
     $ref: /schemas/types.yaml#/definitions/uint32
     enum: [1, 2, 4, 8]
 
+  fast-io:
+    description:
+      Indicates that this bus has a very fast IO, for which
+      different locking methods should be used to reduce
+      overhead (e.g. spinlock instead of mutex).
+    type: boolean
+
   hwlocks:
     maxItems: 1
     description:
       Reference to a phandle of a hardware spinlock provider node.
 
+if:
+  required:
+    - hwlocks
+then:
+  not:
+    required:
+      - fast-io
+
 required:
   - compatible
   - reg
-- 
2.35.1