Re: [PATCH 5/7] riscv: dts: bouffalolab: add the bl808 SoC base device tree

From: Icenowy Zheng <uwu@icenowy.me>
To: Emil Renner Berthing <emil.renner.berthing@canonical.com>,
	Jisheng Zhang <jszhang@kernel.org>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
	Rob Herring <robh+dt@kernel.org>,
	Krzysztof Kozlowski <krzysztof.kozlowski+dt@linaro.org>,
	Paul Walmsley <paul.walmsley@sifive.com>,
	Palmer Dabbelt <palmer@dabbelt.com>,
	Albert Ou <aou@eecs.berkeley.edu>,
	Jiri Slaby <jirislaby@kernel.org>,
	linux-serial@vger.kernel.org, devicetree@vger.kernel.org,
	linux-kernel@vger.kernel.org, linux-riscv@lists.infradead.org
Subject: Re: [PATCH 5/7] riscv: dts: bouffalolab: add the bl808 SoC base device tree
Date: Mon, 21 Nov 2022 11:36:50 +0800	[thread overview]
Message-ID: <540beefcad5f9921068d54d056f168a4c45ffeaf.camel@icenowy.me> (raw)
In-Reply-To: <CAJM55Z_f=zp3Z=wno_yr7csAUMQ472RiZXD19CrDTTxmGAmU4w@mail.gmail.com>

在 2022-11-20星期日的 15:57 +0100，Emil Renner Berthing写道：
> On Sun, 20 Nov 2022 at 09:32, Jisheng Zhang <jszhang@kernel.org>
> wrote:
> > 
> > Add a baisc dtsi for the bouffalolab bl808 SoC.
> > 
> > Signed-off-by: Jisheng Zhang <jszhang@kernel.org>
> > ---
> >  arch/riscv/boot/dts/Makefile               |  1 +
> >  arch/riscv/boot/dts/bouffalolab/bl808.dtsi | 74
> > ++++++++++++++++++++++
> >  2 files changed, 75 insertions(+)
> >  create mode 100644 arch/riscv/boot/dts/bouffalolab/bl808.dtsi
> > 
> > diff --git a/arch/riscv/boot/dts/Makefile
> > b/arch/riscv/boot/dts/Makefile
> > index ff174996cdfd..b525467152b2 100644
> > --- a/arch/riscv/boot/dts/Makefile
> > +++ b/arch/riscv/boot/dts/Makefile
> > @@ -1,4 +1,5 @@
> >  # SPDX-License-Identifier: GPL-2.0
> > +subdir-y += bouffalolab
> >  subdir-y += sifive
> >  subdir-y += starfive
> >  subdir-$(CONFIG_SOC_CANAAN_K210_DTB_BUILTIN) += canaan
> > diff --git a/arch/riscv/boot/dts/bouffalolab/bl808.dtsi
> > b/arch/riscv/boot/dts/bouffalolab/bl808.dtsi
> > new file mode 100644
> > index 000000000000..c98ebb14ee10
> > --- /dev/null
> > +++ b/arch/riscv/boot/dts/bouffalolab/bl808.dtsi
> > @@ -0,0 +1,74 @@
> > +// SPDX-License-Identifier: (GPL-2.0+ or MIT)
> > +/*
> > + * Copyright (C) 2022 Jisheng Zhang <jszhang@kernel.org>
> > + */
> > +
> > +#include <dt-bindings/interrupt-controller/irq.h>
> > +
> > +/ {
> > +       compatible = "bouffalolab,bl808";
> > +       #address-cells = <1>;
> > +       #size-cells = <1>;
> > +
> > +       cpus {
> > +               timebase-frequency = <1000000>;
> > +               #address-cells = <1>;
> > +               #size-cells = <0>;
> > +
> > +               cpu0: cpu@0 {
> > +                       compatible = "thead,c906", "riscv";
> > +                       device_type = "cpu";
> > +                       reg = <0>;
> > +                       d-cache-block-size = <64>;
> > +                       d-cache-sets = <256>;
> > +                       d-cache-size = <32768>;
> > +                       i-cache-block-size = <64>;
> > +                       i-cache-sets = <128>;
> > +                       i-cache-size = <32768>;
> > +                       mmu-type = "riscv,sv39";
> > +                       riscv,isa = "rv64imafdc";
> > +
> > +                       cpu0_intc: interrupt-controller {
> > +                               compatible = "riscv,cpu-intc";
> > +                               interrupt-controller;
> > +                               #address-cells = <0>;
> > +                               #interrupt-cells = <1>;
> > +                       };
> > +               };
> > +       };
> > +
> > +       xtal: xtal-clk {
> > +               compatible = "fixed-clock";
> > +               clock-frequency = <40000000>;
> 
> This was discussed many times before, but I think the conclusion was
> that the frequency is a property of the crystal on the board, so this
> should be 0 in the SoC dtsi, and then overwritten in the board device
> tree.

But many chips just specify an accepted frequency in their datasheet,
and using a frequency other than this is undefined behavior.

> 
> > +               clock-output-names = "xtal";
> > +               #clock-cells = <0>;
> > +       };
> > +
> > +       soc {
> > +               compatible = "simple-bus";
> > +               ranges;
> > +               interrupt-parent = <&plic>;
> > +               dma-noncoherent;
> > +               #address-cells = <1>;
> > +               #size-cells = <1>;
> > +
> > +               uart0: serial@30002000 {
> > +                       compatible = "bouffalolab,uart";
> > +                       reg = <0x30002000 0x1000>;
> > +                       interrupts = <20 IRQ_TYPE_LEVEL_HIGH>;
> > +                       clocks = <&xtal>;
> > +                       status = "disabled";
> > +               };
> > +
> > +               plic: interrupt-controller@e0000000 {
> > +                       compatible = "thead,c900-plic";
> > +                       reg = <0xe0000000 0x4000000>;
> > +                       interrupts-extended = <&cpu0_intc
> > 0xffffffff>,
> > +                                             <&cpu0_intc 9>;
> > +                       interrupt-controller;
> > +                       #address-cells = <0>;
> > +                       #interrupt-cells = <2>;
> > +                       riscv,ndev = <64>;
> > +               };
> > +       };
> > +};
> > --
> > 2.37.2
> > 
> > 
> > _______________________________________________
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> > linux-riscv@lists.infradead.org
> > http://lists.infradead.org/mailman/listinfo/linux-riscv
> 
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