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

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Message-ID: <4cf2c655-053f-4ab7-a807-a63a1150e7bc@tuxon.dev>
Date: Fri, 26 Sep 2025 07:38:32 +0300
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] soc: renesas: rz-sysc: Populate
 readable_reg/writeable_reg in regmap config

Hi, Geert,

On 9/25/25 17:05, Geert Uytterhoeven wrote:
> Hi Claudiu,
> 
> On Mon, 22 Sept 2025 at 09:41, 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>
> 
> Thanks for your patch!
> 
>> --- a/drivers/soc/renesas/r9a08g045-sysc.c
>> +++ b/drivers/soc/renesas/r9a08g045-sysc.c
>> @@ -6,10 +6,14 @@
>>   */
>>
>>  #include <linux/bits.h>
>> +#include <linux/device.h>
>>  #include <linux/init.h>
>>
>>  #include "rz-sysc.h"
>>
>> +#define SYS_USB_PWRRDY         0xd70
>> +#define SYS_PCIE_RST_RSM_B     0xd74
>> +
>>  static const struct rz_sysc_soc_id_init_data rzg3s_sysc_soc_id_init_data __initconst = {
>>         .family = "RZ/G3S",
>>         .id = 0x85e0447,
>> @@ -18,7 +22,20 @@ 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_USB_PWRRDY:
>> +       case SYS_PCIE_RST_RSM_B:
> 
> Given upstream has already support for RZ/G3S Ethernet, it may be wise
> to add the GEther0/1 Config Registers at 0x380/0x390, too.  That way
> you avoid a possible future hard dependency and regression when adding
> support for configuring that register from the Ethernet driver.
> The same is true for RZ/G3E, RZ/V2H, and RZ/V2N.

Ok, I'll update.

> 
>> +               return true;
>> +       default:
>> +               return false;
>> +       }
>> +}
>> +
>>  const struct rz_sysc_init_data rzg3s_sysc_init_data __initconst = {
>>         .soc_id_init_data = &rzg3s_sysc_soc_id_init_data,
>> +       .readable_reg = rzg3s_regmap_readable_reg,
>> +       .writeable_reg = rzg3s_regmap_readable_reg,
>>         .max_register = 0xe20,
>>  };
> 
>> --- a/drivers/soc/renesas/r9a09g056-sys.c
>> +++ b/drivers/soc/renesas/r9a09g056-sys.c
>> @@ -70,6 +70,13 @@ static const struct rz_sysc_soc_id_init_data rzv2n_sys_soc_id_init_data __initco
>>         .print_id = rzv2n_sys_print_id,
>>  };
>>
>> +static bool rzv2n_regmap_readable_reg(struct device *dev, unsigned int reg)
>> +{
>> +       return false;
> 
> I would already add the TRU trimming registers, also for RZ/V2H, as
> they can probably just reuse the RZ/G3E TSU driver.

Wasn't aware of it. I'll check it.

> 
>> +}
>> +
>>  const struct rz_sysc_init_data rzv2n_sys_init_data = {
>>         .soc_id_init_data = &rzv2n_sys_soc_id_init_data,
>> +       .readable_reg = rzv2n_regmap_readable_reg,
>> +       .writeable_reg = rzv2n_regmap_readable_reg,
> 
> Oops, this one does not have ".max_register = 0x170c" yet.
> Does this cause any ill effects that warrant an urgent fix?

Yes, similar crash. I wrongly checked it initially. I'll update it.

Thank you for your review,
Claudiu

> 
>>  };
> 
> Gr{oetje,eeting}s,
> 
>                         Geert
>