Re: [PATCH v2 1/2] dt-bindings: timer: thead,c900-aclint-mtimer: separate mtime and mtimecmp regs

From: Conor Dooley <conor@kernel.org>
To: Inochi Amaoto <inochiama@outlook.com>
Cc: Chen Wang <unicorn_wang@outlook.com>,
	Daniel Lezcano <daniel.lezcano@linaro.org>,
	Thomas Gleixner <tglx@linutronix.de>,
	Rob Herring <robh+dt@kernel.org>,
	Krzysztof Kozlowski <krzysztof.kozlowski+dt@linaro.org>,
	Conor Dooley <conor+dt@kernel.org>,
	Paul Walmsley <paul.walmsley@sifive.com>,
	Palmer Dabbelt <palmer@dabbelt.com>,
	Albert Ou <aou@eecs.berkeley.edu>, Guo Ren <guoren@kernel.org>,
	Jisheng Zhang <jszhang@kernel.org>,
	linux-kernel@vger.kernel.org, devicetree@vger.kernel.org,
	linux-riscv@lists.infradead.org
Subject: Re: [PATCH v2 1/2] dt-bindings: timer: thead,c900-aclint-mtimer: separate mtime and mtimecmp regs
Date: Tue, 14 Nov 2023 15:21:48 +0000	[thread overview]
Message-ID: <20231114-outweigh-sandbank-6bbdd7ea3286@squawk> (raw)
In-Reply-To: <IA1PR20MB4953EBB4DA58A7170D865B0CBBB2A@IA1PR20MB4953.namprd20.prod.outlook.com>

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On Tue, Nov 14, 2023 at 09:45:33AM +0800, Inochi Amaoto wrote:
> >On 2023/11/14 8:45, Inochi Amaoto wrote:
> >> 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 introduces a new type of T-HEAD aclint timer which
> >> has clint timer layout. Although the timer has the clint 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 two regs
> >> to represent the mtime and mtimecmp.
> >>
> >> Signed-off-by: Inochi Amaoto <inochiama@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
> >> ---
> >>   .../devicetree/bindings/timer/thead,c900-aclint-mtimer.yaml  | 5 +++--
> >>   1 file changed, 3 insertions(+), 2 deletions(-)
> >>
> >> diff --git a/Documentation/devicetree/bindings/timer/thead,c900-aclint-mtimer.yaml b/Documentation/devicetree/bindings/timer/thead,c900-aclint-mtimer.yaml
> >> index fbd235650e52..c3080962d902 100644
> >> --- a/Documentation/devicetree/bindings/timer/thead,c900-aclint-mtimer.yaml
> >> +++ b/Documentation/devicetree/bindings/timer/thead,c900-aclint-mtimer.yaml
> >> @@ -17,7 +17,7 @@ properties:
> >>         - const: thead,c900-aclint-mtimer
> >>
> >>     reg:
> >> -    maxItems: 1
> >> +    maxItems: 2
> >
> >The first one is for mtime and the second one is for mtimecmp, right?
> 
> Yes, that is right.
> 
> >Recommend to add some comment in binding file to make it clear.
> >
> 
> Thanks for your advice.

Sorry for not noticing that on v1 - you should indeed describe these in
the binding, by using the items property.

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