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[88.152.144.157]) by smtp.gmail.com with ESMTPSA id z8sm1830913wrq.16.2021.10.20.04.42.54 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Wed, 20 Oct 2021 04:42:54 -0700 (PDT) Message-ID: Date: Wed, 20 Oct 2021 13:42:53 +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: Anup Patel Cc: Daniel Lezcano , Thomas Gleixner , Guo Ren , Bin Meng , Xiang W , Samuel Holland , Atish Patra , Rob Herring , Palmer Dabbelt , Paul Walmsley , Anup Patel , "linux-kernel@vger.kernel.org List" , DTML , linux-riscv , OpenSBI 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 10/20/21 13:27, Anup Patel wrote: > On Wed, Oct 20, 2021 at 3:06 PM 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 > > T-HEAD supporting only 32bit accesses to MTIME and MTIMECMP > registers are totally allowed. The RISC-V privileged specification does > not enforce RV64 platforms to support 64bit accesses to MTIME and > MTIMECMP registers. Also, the ACLINT specification only states > that MTIME and MTIMECMP registers are 64-bit wide but it does > not enforce platforms to support 64-bit accesses. > > Here are some discussions from tech-aia mailing list: > https://lists.riscv.org/g/tech-aia/message/115 > https://lists.riscv.org/g/tech-aia/message/119 > https://lists.riscv.org/g/tech-aia/message/120 > > In other words, the T-HEAD CLINT (MTIMER+MSWI) is compliant > with the RISC-V ACLINT specification. > > I think we should add implementation specific compatible strings > for Allwinner D1 in the ACLINT MTIMER and ACLINT MSWI > DT bindings. > > How about including the following two compatible strings in > ACLINT DT bindings ? > allwinner,sun20i-d1-aclint-mtimer > allwinner,sun20i-d1-aclint-mswi If the Allwinner CLINT is sufficiently compliant, this makes sense to me. Will there be a new round of [RFC PATCH v4 08/10] dt-bindings: timer: Add ACLINT MTIMER bindings https://lore.kernel.org/all/20211007123632.697666-9-anup.patel@wdc.com/ were you could add the Allwinner device? Or is that series already merged? Should the riscv,aclint-mtimer.yaml file mention that there are different access sizes and either state per compatibility string what that size is or provide a parameter for that purpose? Best regards Heinrich > > Regards, > Anup > >> --- >> .../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. >> + >> + reg: >> + maxItems: 1 >> + >> + interrupts-extended: >> + minItems: 1 >> + >> +additionalProperties: false >> + >> +required: >> + - compatible >> + - reg >> + - interrupts-extended >> + >> +examples: >> + - | >> + timer@2000000 { >> + compatible = "allwinner,sun20i-d1-clint", "thead,clint0"; >> + interrupts-extended = <&cpu1intc 3 &cpu1intc 7 >> + &cpu2intc 3 &cpu2intc 7 >> + &cpu3intc 3 &cpu3intc 7 >> + &cpu4intc 3 &cpu4intc 7>; >> + reg = <0x2000000 0x10000>; >> + }; >> +... >> -- >> 2.32.0 >>