Re: [PATCH v5 4/4] dt-bindings: timer: Add CLINT bindings

From: Rob Herring <robh@kernel.org>
To: Anup Patel <anup.patel@wdc.com>
Cc: Palmer Dabbelt <palmer@dabbelt.com>,
	Paul Walmsley <paul.walmsley@sifive.com>,
	Albert Ou <aou@eecs.berkeley.edu>,
	Daniel Lezcano <daniel.lezcano@linaro.org>,
	Thomas Gleixner <tglx@linutronix.de>,
	Damien Le Moal <damien.lemoal@wdc.com>,
	Atish Patra <atish.patra@wdc.com>,
	Alistair Francis <Alistair.Francis@wdc.com>,
	Anup Patel <anup@brainfault.org>,
	linux-riscv@lists.infradead.org, linux-kernel@vger.kernel.org,
	devicetree@vger.kernel.org,
	Palmer Dabbelt <palmerdabbelt@google.com>,
	Emil Renner Berhing <kernel@esmil.dk>
Subject: Re: [PATCH v5 4/4] dt-bindings: timer: Add CLINT bindings
Date: Thu, 23 Jul 2020 11:08:06 -0600	[thread overview]
Message-ID: <20200723170806.GA535824@bogus> (raw)
In-Reply-To: <20200723142409.47057-5-anup.patel@wdc.com>

On Thu, Jul 23, 2020 at 07:54:09PM +0530, Anup Patel wrote:
> We add DT bindings documentation for CLINT device.
> 
> Signed-off-by: Anup Patel <anup.patel@wdc.com>
> Reviewed-by: Palmer Dabbelt <palmerdabbelt@google.com>
> Tested-by: Emil Renner Berhing <kernel@esmil.dk>
> ---
>  .../bindings/timer/sifive,clint.yaml          | 58 +++++++++++++++++++
>  1 file changed, 58 insertions(+)
>  create mode 100644 Documentation/devicetree/bindings/timer/sifive,clint.yaml
> 
> diff --git a/Documentation/devicetree/bindings/timer/sifive,clint.yaml b/Documentation/devicetree/bindings/timer/sifive,clint.yaml
> new file mode 100644
> index 000000000000..8ad115611860
> --- /dev/null
> +++ b/Documentation/devicetree/bindings/timer/sifive,clint.yaml
> @@ -0,0 +1,58 @@
> +# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
> +%YAML 1.2
> +---
> +$id: http://devicetree.org/schemas/timer/sifive,clint.yaml#
> +$schema: http://devicetree.org/meta-schemas/core.yaml#
> +
> +title: SiFive Core Local Interruptor
> +
> +maintainers:
> +  - Palmer Dabbelt <palmer@dabbelt.com>
> +  - Anup Patel <anup.patel@wdc.com>
> +
> +description:
> +  SiFive (and other RISC-V) SOCs include an implementation of the SiFive
> +  Core Local Interruptor (CLINT) for M-mode timer and M-mode inter-processor
> +  interrupts. It directly connects to the timer and inter-processor interrupt
> +  lines of various HARTs (or CPUs) so RISC-V per-HART (or per-CPU) local
> +  interrupt controller is the parent interrupt controller for CLINT device.
> +  The clock frequency of CLINT 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:
> +      - const: sifive,clint0
> +      - const: sifive,fu540-c000-clint

Wrong order. Most specific goes first.

> +
> +    description:
> +      Should be "sifive,<chip>-clint" and "sifive,clint<version>".
> +      Supported compatible strings are -
> +      "sifive,fu540-c000-clint" for the SiFive CLINT v0 as integrated
> +      onto the SiFive FU540 chip, and "sifive,clint0" for the SiFive
> +      CLINT v0 IP block with no chip integration tweaks.
> +      Please refer to sifive-blocks-ip-versioning.txt for details
> +
> +  reg:
> +    maxItems: 1
> +
> +  interrupts-extended:
> +    minItems: 1
> +
> +required:
> +  - compatible
> +  - reg
> +  - interrupts-extended

Add:

additionalProperties: false

> +
> +examples:
> +  - |
> +    clint@2000000 {

timer@...

> +      compatible = "sifive,clint0", "sifive,fu540-c000-clint";
> +      interrupts-extended = <&cpu1intc 3 &cpu1intc 7
> +                             &cpu2intc 3 &cpu2intc 7
> +                             &cpu3intc 3 &cpu3intc 7
> +                             &cpu4intc 3 &cpu4intc 7>;
> +       reg = <0x2000000 0x4000000>;

64MB of register space? Doesn't matter much for 64-bit, but would waste 
lots of virtual space (low mem) on 32-bit.

> +    };
> +...
> -- 
> 2.25.1
> 