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[88.152.144.157]) by smtp.gmail.com with ESMTPSA id a16sm9182038wrp.14.2021.10.22.17.03.13 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Fri, 22 Oct 2021 17:03:13 -0700 (PDT) Message-ID: <6d642c10-27b1-72bd-a38e-f966ae8831f0@canonical.com> Date: Sat, 23 Oct 2021 02:03:12 +0200 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:91.0) Gecko/20100101 Thunderbird/91.1.2 Subject: Re: [PATCH 1/1] dt-bindings: T-HEAD CLINT Content-Language: en-US To: Rob Herring Cc: Daniel Lezcano , Thomas Gleixner , Guo Ren , Bin Meng , Xiang W , Samuel Holland , Atish Patra , Palmer Dabbelt , Paul Walmsley , Anup Patel , linux-kernel@vger.kernel.org, devicetree@vger.kernel.org, linux-riscv@lists.infradead.org, opensbi@lists.infradead.org References: <20211020093603.28653-1-heinrich.schuchardt@canonical.com> From: Heinrich Schuchardt In-Reply-To: Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 10/22/21 23:22, Rob Herring wrote: > On Wed, Oct 20, 2021 at 11:36:03AM +0200, Heinrich Schuchardt wrote: >> The CLINT in the T-HEAD 9xx CPUs is similar to the SiFive CLINT but does >> not support 64bit mmio access to the MTIMER device. >> >> OpenSBI currently uses a property 'clint,has-no-64bit-mmio' to indicate the >> restriction and the "sifive,cling0" compatible string. An OpenSBI >> patch suggested to use "reg-io-width = <4>;" as the reg-io-width property >> is generally used in the devicetree schema for such a condition. >> >> As the design is not SiFive based it is preferable to apply a compatible >> string identifying T-HEAD instead. >> >> Add a new yaml file describing the T-HEAD CLINT. >> >> Signed-off-by: Heinrich Schuchardt >> --- >> @Palmer, @Anup >> I copied you as maintainers from sifive,clint.yaml. Please, indicate if >> this should be changed. >> >> For the prior discussion see: >> https://lore.kernel.org/all/20211015100941.17621-1-heinrich.schuchardt@canonical.com/ >> https://lore.kernel.org/all/20211015120735.27972-1-heinrich.schuchardt@canonical.com/ >> >> A release candidate of the ACLINT specification is available at >> https://github.com/riscv/riscv-aclint/releases >> --- >> .../bindings/timer/thead,clint.yaml | 62 +++++++++++++++++++ >> 1 file changed, 62 insertions(+) >> create mode 100644 Documentation/devicetree/bindings/timer/thead,clint.yaml >> >> diff --git a/Documentation/devicetree/bindings/timer/thead,clint.yaml b/Documentation/devicetree/bindings/timer/thead,clint.yaml >> new file mode 100644 >> index 000000000000..02463fb2043a >> --- /dev/null >> +++ b/Documentation/devicetree/bindings/timer/thead,clint.yaml >> @@ -0,0 +1,62 @@ >> +# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause) >> +%YAML 1.2 >> +--- >> +$id: http://devicetree.org/schemas/timer/thead,clint.yaml# >> +$schema: http://devicetree.org/meta-schemas/core.yaml# >> + >> +title: SiFive Core Local Interruptor >> + >> +maintainers: >> + - Palmer Dabbelt >> + - Anup Patel >> + >> +description: >> + T-HEAD (and other RISC-V) SOCs include an implementation of the T-HEAD >> + 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 the 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: >> + - allwinner,sun20i-d1-clint >> + - const: >> + - thead,clint0 >> + >> + description: >> + Should be ",-clint" and "thead,clint" for >> + the T-HEAD derived CLINTs. >> + Supported compatible strings are - >> + "allwinner,sun20i-d1-clint" for the CLINT in the Allwinner D1 SoC >> + and "thead,clint0" for the T-HEAD IP block with no chip >> + integration tweaks. > > T-HEAD uses the same versioning as SiFive? If you use version numbers in > compatible strings, the numbering needs to be documented and correlate > back to the h/w design. See [1]. IP release numbers for FPGA IP for > example. What it should not be is the binding author making up 0, 1, 2, > etc. versions. The only publicly available information on the IP block is: https://github.com/T-head-Semi/openc906/blob/main/doc/%E7%8E%84%E9%93%81C906%E7%94%A8%E6%88%B7%E6%89%8B%E5%86%8C.pdf Page 3 has a version number for the whole document. Chapter 9 does not have any version number for the CLINT. So should we simply call the block "thead,clint" without any version number? @Guo: do you have more information accessible? Best regards Heinrich > > Rob > > [1] Documentation/devicetree/bindings/sifive/sifive-blocks-ip-versioning.txt >