linux-kernel - Re: [PATCH 2/2] soc: renesas: rz-sysc: Populate readable_reg/writeable

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Message-ID: <6369d978-a067-42b3-8384-c5d8814a1506@tuxon.dev>
Date: Fri, 14 Nov 2025 13:46:18 +0200
From: Claudiu Beznea <claudiu.beznea@...on.dev>
To: Geert Uytterhoeven <geert@...ux-m68k.org>
Cc: magnus.damm@...il.com, john.madieu.xa@...renesas.com,
 linux-renesas-soc@...r.kernel.org, linux-kernel@...r.kernel.org,
 Claudiu Beznea <claudiu.beznea.uj@...renesas.com>
Subject: Re: [PATCH 2/2] soc: renesas: rz-sysc: Populate
 readable_reg/writeable_reg in regmap config

Hi, Geert,

On 11/13/25 21:15, Geert Uytterhoeven wrote:
> Hi Claudiu,
> 
> On Wed, 5 Nov 2025 at 08:05, Claudiu <claudiu.beznea@...on.dev> wrote:
>> From: Claudiu Beznea <claudiu.beznea.uj@...renesas.com>
>>
>> Not all system controller registers are accessible from Linux. Accessing
>> such registers generates synchronous external abort. Populate the
>> readable_reg and writeable_reg members of the regmap config to inform the
>> regmap core which registers can be accessed. The list will need to be
>> updated whenever new system controller functionality is exported through
>> regmap.
>>
>> Fixes: 2da2740fb9c8 ("soc: renesas: rz-sysc: Add syscon/regmap support")
>> Signed-off-by: Claudiu Beznea <claudiu.beznea.uj@...renesas.com>
>> ---
>>
>> Changes in v2:
>> - added all SYSC registers IP specific, except the SPI
>>   registers on RZ/V2H and RZ/V2N as these are accessible only from EL3
> 
> Reviewed-by: Geert Uytterhoeven <geert+renesas@...der.be>
> i.e. will queue in renesas-devel for v6.19.
> 
>> --- a/drivers/soc/renesas/r9a08g045-sysc.c
>> +++ b/drivers/soc/renesas/r9a08g045-sysc.c
> 
>> @@ -18,7 +37,57 @@ static const struct rz_sysc_soc_id_init_data rzg3s_sysc_soc_id_init_data __initc
>>         .specific_id_mask = GENMASK(27, 0),
>>  };
>>
>> +static bool rzg3s_regmap_readable_reg(struct device *dev, unsigned int reg)
>> +{
>> +       switch (reg) {
>> +       case SYS_XSPI_MAP_STAADD_CS0:
>> +       case SYS_XSPI_MAP_ENDADD_CS0:
>> +       case SYS_XSPI_MAP_STAADD_CS1:
>> +       case SYS_XSPI_MAP_ENDADD_CS1:
>> +       case SYS_GETH0_CFG:
>> +       case SYS_GETH1_CFG:
>> +       case SYS_PCIE_CFG:
>> +       case SYS_PCIE_MON:
>> +       case SYS_PCIE_ERR_MON:
>> +       case SYS_PCIE_PHY:
>> +       case SYS_I2C0_CFG:
>> +       case SYS_I2C1_CFG:
>> +       case SYS_I2C2_CFG:
>> +       case SYS_I2C3_CFG:
>> +       case SYS_I3C_CFG:
>> +       case SYS_USB_PWRRDY:
>> +       case SYS_PCIE_RST_RSM_B:
>> +               return true;
>> +       default:
>> +               return false;
>> +       }
>> +}
>> +
>> +static bool rzg3s_regmap_writeable_reg(struct device *dev, unsigned int reg)
>> +{
>> +       switch (reg) {
>> +       case SYS_XSPI_MAP_STAADD_CS0:
>> +       case SYS_XSPI_MAP_ENDADD_CS0:
>> +       case SYS_XSPI_MAP_STAADD_CS1:
>> +       case SYS_XSPI_MAP_ENDADD_CS1:
>> +       case SYS_PCIE_CFG:
>> +       case SYS_PCIE_PHY:
>> +       case SYS_I2C0_CFG:
>> +       case SYS_I2C1_CFG:
>> +       case SYS_I2C2_CFG:
>> +       case SYS_I2C3_CFG:
>> +       case SYS_I3C_CFG:
>> +       case SYS_USB_PWRRDY:
>> +       case SYS_PCIE_RST_RSM_B:
>> +               return true;
>> +       default:
>> +               return false;
>> +       }
>> +}
> 
> As all the writeable regs are a subset of the readable regs, do you
> think it would be worthwhile to write e.g.
> 
>     static bool rzg3s_regmap_readable_reg(struct device *dev, unsigned int reg)
>     {
>             if (rzg3s_regmap_writeable_reg(dev, reg))
>                     return true;
> 
>             switch (reg) {
>             case SYS_GETH0_CFG:
>             case SYS_GETH1_CFG:
>             case SYS_PCIE_MON:
>             case SYS_PCIE_ERR_MON:
>                     return true;
>             default:
>                     return false;
>             }
>     }

Looks ok to me as well. I chose to have it like this as most of the
readable/writeable function that I remember to have seen in the past were
in the format I've presented in this patch.

I noticed you already sent the PR. Would you prefer to return with a follow
up patch and adjust it as you suggested?

Thank you,
Claudiu