[RFC PATCH v4 08/10] dt-bindings: timer: Add ACLINT MTIMER bindings

[Anup Patel <anup.patel@wdc.com>]

We add DT bindings documentation for the ACLINT MTIMER device
found on RISC-V SOCs.

Signed-off-by: Anup Patel <anup.patel@wdc.com>
Reviewed-by: Bin Meng <bmeng.cn@gmail.com>
---
 .../bindings/timer/riscv,aclint-mtimer.yaml   | 67 +++++++++++++++++++
 1 file changed, 67 insertions(+)
 create mode 100644 Documentation/devicetree/bindings/timer/riscv,aclint-mtimer.yaml

diff --git a/Documentation/devicetree/bindings/timer/riscv,aclint-mtimer.yaml b/Documentation/devicetree/bindings/timer/riscv,aclint-mtimer.yaml
new file mode 100644
index 000000000000..ebb7e81a5a12
--- /dev/null
+++ b/Documentation/devicetree/bindings/timer/riscv,aclint-mtimer.yaml
@@ -0,0 +1,67 @@
+# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
+%YAML 1.2
+---
+$id: http://devicetree.org/schemas/timer/riscv,aclint-mtimer.yaml#
+$schema: http://devicetree.org/meta-schemas/core.yaml#
+
+title: RISC-V ACLINT M-level Timer
+
+maintainers:
+  - Anup Patel <anup.patel@wdc.com>
+
+description:
+  RISC-V SOCs include an implementation of the M-level timer (MTIMER) defined
+  in the RISC-V Advanced Core Local Interruptor (ACLINT) specification. The
+  ACLINT MTIMER device is documented in the RISC-V ACLINT specification found
+  at https://github.com/riscv/riscv-aclint/blob/main/riscv-aclint.adoc.
+
+  The ACLINT MTIMER device directly connects to the M-level timer interrupt
+  lines of various HARTs (or CPUs) so the RISC-V per-HART (or per-CPU) local
+  interrupt controller is the parent interrupt controller for the ACLINT
+  MTIMER device.
+
+  The clock frequency of ACLINT is specified via "timebase-frequency" DT
+  property of "/cpus" DT node. The "timebase-frequency" DT property is
+  described in Documentation/devicetree/bindings/riscv/cpus.yaml
+
+properties:
+  compatible:
+    items:
+      - enum:
+         - sifive,fu540-c000-aclint-mtimer
+      - const: riscv,aclint-mtimer
+
+    description:
+      Should be "<vendor>,<chip>-aclint-mtimer" and "riscv,aclint-mtimer".
+
+  reg:
+    description: |
+      Specifies base physical address(s) of the MTIME register and MTIMECMPx
+      registers. The 1st region is the MTIME register base and size. The 2nd
+      region is the MTIMECMPx registers base and size.
+    minItems: 2
+    maxItems: 2
+
+  interrupts-extended:
+    minItems: 1
+    maxItems: 4095
+
+additionalProperties: false
+
+required:
+  - compatible
+  - reg
+  - interrupts-extended
+
+examples:
+  - |
+    timer@2004000 {
+      compatible = "sifive,fu540-c000-aclint-mtimer", "riscv,aclint-mtimer";
+      reg = <0x200bff8 0x8>,
+            <0x2004000 0x7ff8>;
+      interrupts-extended = <&cpu1intc 7>,
+                            <&cpu2intc 7>,
+                            <&cpu3intc 7>,
+                            <&cpu4intc 7>;
+    };
+...
-- 
2.25.1