Re: [PATCH v1 15/30] clk: starfive: Use regmap APIs to operate registers

[Hal Feng <hal.feng@xxxxxxxxxxxxxxxxxxxxxx>]

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 = &pdev->dev;
> > > > -       priv->base = devm_platform_ioremap_resource(pdev, 0);
> > > > -       if (IS_ERR(priv->base))
> > > > -               return PTR_ERR(priv->base);
> > > > +       priv->regmap = device_node_to_regmap(priv->dev->of_node);
> > >
> > > This is sad. 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)?
> > 
> > In my original code the clock driver just registers the resets too
> > similar to other combined clock and reset drivers. I wonder what you
> > think about that approach:
> > https://github.com/esmil/linux/commit/36f15e1b827b02d7f493dc5fce31060b21976e68
> > and
> > https://github.com/esmil/linux/commit/4ccafadb72968480aa3dd28c227fcccae411c13b#diff-ffec81f902f810cb210012c25e8d88217ea5b4021419a4206d1fd4dd19edfce8R471
> 
> 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. That
> way the appropriate maintainers can review the code. There is only one
> platform device with a single reg property and node in DT, but there are
> two drivers. 

Yes, I agree that the reset driver and the clock driver should be split.
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 
JH7110. They just share a common register base address. I think it is 
better to use ioremap for the same address, and the dt will be like

syscrg_clk: clock-controller@13020000 {
	compatible = "starfive,jh7110-clkgen-sys";
	reg = <0x0 0x13020000 0x0 0x10000>;
	...
};
syscrg_rst: reset-controller@13020000 {
	compatible = "starfive,jh7110-reset-sys";
	reg = <0x0 0x13020000 0x0 0x10000>;
	...
};

What do you think of this approach? I would appreciate your suggestions.

Best regards,
Hal