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Date:   Sun, 23 Oct 2022 11:25:26 +0100
From:   Conor Dooley <conor@kernel.org>
To:     Hal Feng <hal.feng@linux.starfivetech.com>,
        Stephen Boyd <sboyd@kernel.org>
CC:     Emil Renner Berthing <emil.renner.berthing@canonical.com>,
        devicetree@vger.kernel.org, linux-clk@vger.kernel.org,
        linux-gpio@vger.kernel.org, linux-riscv@lists.infradead.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>,
        Daniel Lezcano <daniel.lezcano@linaro.org>,
        Thomas Gleixner <tglx@linutronix.de>,
        Marc Zyngier <maz@kernel.org>,
        Philipp Zabel <p.zabel@pengutronix.de>,
        Michael Turquette <mturquette@baylibre.com>,
        Linus Walleij <linus.walleij@linaro.org>,
        Emil Renner Berthing <kernel@esmil.dk>,
        linux-kernel@vger.kernel.org
Subject: =?US-ASCII?Q?Re=3A_=5BPATCH_v1_15/30=5D_clk=3A_starfive=3A_?= =?US-ASCII?Q?Use_regmap_APIs_to_operate_registers?=
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On 23 October 2022 05:11:41 IST, Hal Feng <hal=2Efeng@linux=2Estarfivetech=
=2Ecom> wrote:
>On Wed, 12 Oct 2022 16:05:23 -0700, Stephen Boyd wrote:
>> Quoting Emil Renner Berthing (2022-10-05 06:14:44)
>> > > > @@ -295,11 +296,13 @@ static int __init clk_starfive_jh7100_probe=
(struct platform_device *pdev)
>> > > >         if (!priv)
>> > > >                 return -ENOMEM;
>> > > >
>> > > > -       spin_lock_init(&priv->rmw_lock);
>> > > >         priv->dev =3D &pdev->dev;
>> > > > -       priv->base =3D devm_platform_ioremap_resource(pdev, 0);
>> > > > -       if (IS_ERR(priv->base))
>> > > > -               return PTR_ERR(priv->base);
>> > > > +       priv->regmap =3D device_node_to_regmap(priv->dev->of_node=
);
>> > >
>> > > This is sad=2E Why do we need to make a syscon? Can we instead use =
the
>> > > auxiliary bus to make a reset device that either gets a regmap made=
 here
>> > > in this driver or uses a void __iomem * mapped with ioremap
>> > > (priv->base)?
>> >=20
>> > In my original code the clock driver just registers the resets too
>> > similar to other combined clock and reset drivers=2E I wonder what yo=
u
>> > think about that approach:
>> > https://github=2Ecom/esmil/linux/commit/36f15e1b827b02d7f493dc5fce310=
60b21976e68
>> > and
>> > https://github=2Ecom/esmil/linux/commit/4ccafadb72968480aa3dd28c227fc=
ccae411c13b#diff-ffec81f902f810cb210012c25e8d88217ea5b4021419a4206d1fd4dd19=
edfce8R471
>>=20
>> I think we should use auxiliary bus and split the driver logically into
>> a reset driver in drivers/reset and a clk driver in drivers/clk=2E That
>> way the appropriate maintainers can review the code=2E There is only on=
e
>> platform device with a single reg property and node in DT, but there ar=
e
>> two drivers=2E=20
>
>Yes, I agree that the reset driver and the clock driver should be split=
=2E
>However, I think using auxiliary bus is a little bit complicated in this
>case, because the reset is not a part of functionality of the clock in=20
>JH7110=2E They just share a common register base address=2E I think it is=
=20
>better to use ioremap for the same address, and the dt will be like
>
>syscrg_clk: clock-controller@13020000 {
>	compatible =3D "starfive,jh7110-clkgen-sys";
>	reg =3D <0x0 0x13020000 0x0 0x10000>;
>	=2E=2E=2E
>};
>syscrg_rst: reset-controller@13020000 {
>	compatible =3D "starfive,jh7110-reset-sys";
>	reg =3D <0x0 0x13020000 0x0 0x10000>;
>	=2E=2E=2E
>};
>
>What do you think of this approach? I would appreciate your suggestions=
=2E

No, the dtb checks will all start warning for this=2E
Aux bus is not that difficult, you can likely copy much of what I did rece=
ntly in clk-mpfs=2Ec
>
>Best regards,
>Hal