Re: [PATCH RFC v2 2/9] clk: renesas: r9a09g077: Add SYSC regmap support

[Geert Uytterhoeven]

Hi Prabhakar,

On Thu, 2 Jul 2026 at 14:31, Prabhakar <prabhakar.csengg@xxxxxxxxx> wrote:
> From: Lad Prabhakar <prabhakar.mahadev-lad.rj@xxxxxxxxxxxxxx>
>
> Add System Controller (SYSC) regmap support for the RZ/T2H SoC.
>
> The RZ/T2H SoC features two System Controller (SYSC) blocks that handle
> low-power management and access control. These blocks are defined as child
> nodes within the Clock Pulse Generator (CPG) address space in the device
> tree. Implement support for creating regmaps for these SYSC blocks.
>
> Register the regmap using of_syscon_register_regmap() against the CPG
> device node so that consumers can access SYSC registers via the existing
> syscon phandle.
>
> Add a sysc_init() callback to the CPG/MSSR core to allow SoC-specific
> initialization of the SYSC regmap.
>
> Signed-off-by: Lad Prabhakar <prabhakar.mahadev-lad.rj@xxxxxxxxxxxxxx>
> ---
> v1->v2:
> - Made use of for_each_child_of_node_scoped
> - Moved sysc_init() to the end of the probe function

Thanks for the update!

> --- a/drivers/clk/renesas/r9a09g077-cpg.c
> +++ b/drivers/clk/renesas/r9a09g077-cpg.c

> +static bool rzt2h_writeable_readable_sysc0(struct device *dev, unsigned int reg)
> +{
> +       switch (reg) {
> +       case 0x0000 ... 0x0008:
> +       case 0x1000 ... 0x1164:
> +       case 0x2000 ... 0x2024:
> +       case 0x2030 ... 0x2054:
> +       case 0x2060:
> +       case 0x3000 ... 0x300C:
> +       case 0x3100 ... 0x310C:
> +       case 0x4100:
> +       case 0x4200:
> +               return true;
> +
> +       default:
> +               return false;
> +       }
> +}
> +
> +static bool rzt2h_writeable_readable_sysc1(struct device *dev, unsigned int reg)
> +{
> +       switch (reg) {
> +       case 0x000C:
> +       case 0x0034 ... 0x0038:
> +       case 0x0048 ... 0x007C:
> +       case 0x0100 ... 0x017C:
> +       case 0x0200 ... 0x027C:
> +       case 0x0308 ... 0x030C:
> +       case 0x0320 ... 0x037C:
> +       case 0x0480 ... 0x0484:
> +       case 0x0580 ... 0x0584:
> +       case 0x0680 ... 0x0684:
> +       case 0x0780 ... 0x0784:
> +       case 0x0880:
> +       case 0x0980 ... 0x098C:
> +       case 0x1100 ... 0x1118:
> +       case 0x1200 ... 0x1204:
> +       case 0x1400 ... 0x1484:
> +       case 0x1500 ... 0x1584:
> +       case 0x1600 ... 0x1680:
> +       case 0x1700 ... 0x1780:
> +       case 0x1800 ... 0x1884:
> +       case 0x1900 ... 0x1984:
> +       case 0x1A00 ... 0x1A84:
> +       case 0x1B00 ... 0x1B8C:
> +       case 0x1C00 ... 0x1C8C:
> +       case 0x1D00 ... 0x1D8C:
> +       case 0x3000:
> +       case 0x3010:
> +       case 0x3020:
> +       case 0x3030:
> +       case 0x4000:
> +       case 0x5008 ... 0x500C:
> +       case 0x5020 ... 0x503C:
> +       case 0x5100 ... 0x5114:
> +       case 0x6000:
> +               return true;
> +
> +       default:
> +               return false;
> +       }
> +}

This exposes a lot of dangerous registers.  Aren't they also exported
to userspace through drivers/base/regmap/regmap-debugfs.c?

> --- a/drivers/clk/renesas/renesas-cpg-mssr.h
> +++ b/drivers/clk/renesas/renesas-cpg-mssr.h
> @@ -178,6 +178,7 @@ struct cpg_mssr_info {
>
>         /* Callbacks */
>         int (*init)(struct device *dev);
> +       int (*sysc_init)(struct device *dev);

I would rather call it "late_init" or "post_init", as it might become
useful for other purposes, too.

>         struct clk *(*cpg_clk_register)(struct device *dev,
>                                         const struct cpg_core_clk *core,
>                                         const struct cpg_mssr_info *info,
Gr{oetje,eeting}s,

                        Geert

--
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@xxxxxxxxxxxxxx

In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
                                -- Linus Torvalds