[RFC PATCH v3 09/11] dt-bindings: timer: Add ACLINT MTIMER bindings

[Rob Herring]

On Mon, Aug 30, 2021 at 09:47:27AM +0530, Anup Patel wrote:
> We add DT bindings documentation for the ACLINT MTIMER device
> found on RISC-V SOCs.
> 
> Signed-off-by: Anup Patel <anup.patel at wdc.com>
> Reviewed-by: Bin Meng <bmeng.cn at gmail.com>
> ---
>  .../bindings/timer/riscv,aclint-mtimer.yaml   | 70 +++++++++++++++++++
>  1 file changed, 70 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..b0b2ee6c761c
> --- /dev/null
> +++ b/Documentation/devicetree/bindings/timer/riscv,aclint-mtimer.yaml
> @@ -0,0 +1,70 @@
> +# 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 at 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:
> +    enum:
> +      - riscv,aclint-mtimer
> +
> +    description:
> +      Should be "riscv,aclint-mtimer" or "<vendor>,<chip>-aclint-mtimer".

Again, should be AND.

> +
> +  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
> +
> +  mtimer,no-64bit-mmio:
> +    type: boolean
> +    description: If present, the timer does not support 64-bit MMIO accesses
> +      for both MTIME and MTIMECMP registers.

This should be implied by the compatible.

> +
> +additionalProperties: false
> +
> +required:
> +  - compatible
> +  - reg
> +  - interrupts-extended
> +
> +examples:
> +  - |
> +    timer at 2000000 {
> +      compatible = "riscv,aclint-mtimer";
> +      reg = <0x2000000 0x8>,
> +            <0x2004000 0x7ff8>;
> +      interrupts-extended = <&cpu1intc 7>,
> +                            <&cpu2intc 7>,
> +                            <&cpu3intc 7>,
> +                            <&cpu4intc 7>;
> +    };
> +...
> -- 
> 2.25.1
> 
>