[PATCH v4 1/2] dt-bindings: timer: thead,c900-aclint-mtimer: separate mtime and mtimecmp regs

[Inochi Amaoto]

The timer registers of aclint don't follow the clint layout and can
be mapped on any different offset. As sg2042 uses separated timer
and mswi for its clint, it should follow the aclint spec and have
separated registers.

The previous patch introduced a new type of T-HEAD aclint timer which
has clint timer layout. Although it has the clint timer layout, it
should follow the aclint spec and uses the separated mtime and mtimecmp
regs. So a ABI change is needed to make the timer fit the aclint spec.

To make T-HEAD aclint timer more closer to the aclint spec, use
regs-names to represent the mtimecmp register, which can avoid hack
for unsupport mtime register of T-HEAD aclint timer.

Signed-off-by: Inochi Amaoto <inochiama at outlook.com>
Fixes: 4734449f7311 ("dt-bindings: timer: Add Sophgo sg2042 CLINT timer")
Link: https://lists.infradead.org/pipermail/opensbi/2023-October/005693.html
Link: https://github.com/riscv/riscv-aclint/blob/main/riscv-aclint.adoc
---
 .../timer/thead,c900-aclint-mtimer.yaml       | 42 ++++++++++++++++++-
 1 file changed, 41 insertions(+), 1 deletion(-)

diff --git a/Documentation/devicetree/bindings/timer/thead,c900-aclint-mtimer.yaml b/Documentation/devicetree/bindings/timer/thead,c900-aclint-mtimer.yaml
index fbd235650e52..053488fb1286 100644
--- a/Documentation/devicetree/bindings/timer/thead,c900-aclint-mtimer.yaml
+++ b/Documentation/devicetree/bindings/timer/thead,c900-aclint-mtimer.yaml
@@ -17,7 +17,20 @@ properties:
       - const: thead,c900-aclint-mtimer

   reg:
-    maxItems: 1
+    oneOf:
+      - items:
+          - description: MTIME Registers
+          - description: MTIMECMP Registers
+      - items:
+          - description: MTIMECMP Registers
+
+  reg-names:
+    oneOf:
+      - items:
+          - const: mtime
+          - const: mtimecmp
+      - items:
+          - const: mtimecmp

   interrupts-extended:
     minItems: 1
@@ -28,8 +41,34 @@ additionalProperties: false
 required:
   - compatible
   - reg
+  - reg-names
   - interrupts-extended

+allOf:
+  - if:
+      properties:
+        compatible:
+          contains:
+            const: thead,c900-aclint-mtimer
+    then:
+      properties:
+        reg:
+          items:
+            - description: MTIMECMP Registers
+        reg-names:
+          items:
+            - const: mtimecmp
+    else:
+      properties:
+        reg:
+          items:
+            - description: MTIME Registers
+            - description: MTIMECMP Registers
+        reg-names:
+          items:
+            - const: mtime
+            - const: mtimecmp
+
 examples:
   - |
     timer at ac000000 {
@@ -39,5 +78,6 @@ examples:
                             <&cpu3intc 7>,
                             <&cpu4intc 7>;
       reg = <0xac000000 0x00010000>;
+      reg-names = "mtimecmp";
     };
 ...
--
2.42.1