[PATCH 1/1] dt-bindings: reg-io-width for SiFive CLINT

Heinrich Schuchardt heinrich.schuchardt at canonical.com
Fri Oct 15 03:09:41 PDT 2021

The CLINT in the T-HEAD 9xx processors do not support 64bit mmio access to
the MTIMER device. The current schema does not allow to specify this.

OpenSBI currently uses a property 'clint,has-no-64bit-mmio' to indicate the
restriction. Samuael Holland suggested in
lib: utils/timer: Use standard property to specify 32-bit I/O
to use "reg-io-width = <4>;" as the reg-io-width property is generally used
in the devicetree schema for such a condition.

A release candidate of the ACLINT specification is available at

Add reg-io-width as optional property to the SiFive Core Local Interruptor.

Signed-off-by: Heinrich Schuchardt <heinrich.schuchardt at canonical.com>
 Documentation/devicetree/bindings/timer/sifive,clint.yaml | 7 +++++++
 1 file changed, 7 insertions(+)

diff --git a/Documentation/devicetree/bindings/timer/sifive,clint.yaml b/Documentation/devicetree/bindings/timer/sifive,clint.yaml
index a35952f48742..266012d887b5 100644
--- a/Documentation/devicetree/bindings/timer/sifive,clint.yaml
+++ b/Documentation/devicetree/bindings/timer/sifive,clint.yaml
@@ -41,6 +41,13 @@ properties:
     maxItems: 1
+  reg-io-width:
+    description: |
+      Some CLINT implementations, e.g. on the T-HEAD 9xx, only support
+      32bit access for MTIMER.
+    $ref: /schemas/types.yaml#/definitions/uint32
+    const: 4
     minItems: 1

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