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From:   Heinrich Schuchardt <heinrich.schuchardt@canonical.com>
To:     Daniel Lezcano <daniel.lezcano@linaro.org>,
        Thomas Gleixner <tglx@linutronix.de>
Cc:     Guo Ren <guoren@linux.alibaba.com>, Bin Meng <bmeng.cn@gmail.com>,
        Xiang W <wxjstz@126.com>, Samuel Holland <samuel@sholland.org>,
        Atish Patra <atish.patra@wdc.com>,
        Rob Herring <robh+dt@kernel.org>,
        Palmer Dabbelt <palmer@dabbelt.com>,
        Paul Walmsley <paul.walmsley@sifive.com>,
        Anup Patel <anup.patel@wdc.com>, linux-kernel@vger.kernel.org,
        devicetree@vger.kernel.org, linux-riscv@lists.infradead.org,
        opensbi@lists.infradead.org,
        Heinrich Schuchardt <heinrich.schuchardt@canonical.com>
Subject: [PATCH 1/1] dt-bindings: reg-io-width for SiFive CLINT
Date:   Fri, 15 Oct 2021 12:09:41 +0200
Message-Id: <20211015100941.17621-1-heinrich.schuchardt@canonical.com>
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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
https://github.com/smaeul/opensbi/commit/b95e9cf7cf93b0af16fc89204378bc59ff30008e
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
https://github.com/riscv/riscv-aclint/releases

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

Signed-off-by: Heinrich Schuchardt <heinrich.schuchardt@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:
   reg:
     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
+
   interrupts-extended:
     minItems: 1
 
-- 
2.32.0