linux-kernel - RE: [PATCH v4 5/5] thermal: renesas: rzg3e: add support for RZ/T2H and RZ/N2H

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Message-ID:
 <TYRPR01MB15619ECA5180E6F630798DDEE8585A@TYRPR01MB15619.jpnprd01.prod.outlook.com>
Date: Thu, 8 Jan 2026 18:08:38 +0000
From: Cosmin-Gabriel Tanislav <cosmin-gabriel.tanislav.xa@...esas.com>
To: geert <geert@...ux-m68k.org>
CC: John Madieu <john.madieu.xa@...renesas.com>, "Rafael J . Wysocki"
	<rafael@...nel.org>, Daniel Lezcano <daniel.lezcano@...aro.org>, Zhang Rui
	<rui.zhang@...el.com>, Lukasz Luba <lukasz.luba@....com>, Rob Herring
	<robh@...nel.org>, Krzysztof Kozlowski <krzk+dt@...nel.org>, Conor Dooley
	<conor+dt@...nel.org>, Philipp Zabel <p.zabel@...gutronix.de>, magnus.damm
	<magnus.damm@...il.com>, "linux-pm@...r.kernel.org"
	<linux-pm@...r.kernel.org>, "devicetree@...r.kernel.org"
	<devicetree@...r.kernel.org>, "linux-kernel@...r.kernel.org"
	<linux-kernel@...r.kernel.org>, "linux-renesas-soc@...r.kernel.org"
	<linux-renesas-soc@...r.kernel.org>
Subject: RE: [PATCH v4 5/5] thermal: renesas: rzg3e: add support for RZ/T2H
 and RZ/N2H

> From: Geert Uytterhoeven <geert@...ux-m68k.org>
> Sent: Thursday, January 8, 2026 7:43 PM
> 
> Hi Cosmin,
> 
> On Thu, 8 Jan 2026 at 17:55, Cosmin Tanislav
> <cosmin-gabriel.tanislav.xa@...esas.com> wrote:
> > The Renesas RZ/T2H (R9A09G077) and RZ/N2H (R9A09G087) SoCs expose the
> > temperature calibration via SMC SIP and do not have a reset for the
> > TSU peripheral, and use different minimum and maximum temperature values
> > compared to the already supported RZ/G3E.
> >
> > Although the calibration data is stored in an OTP memory, the OTP itself
> > is not memory-mapped, access to it is done through an OTP controller.
> >
> > The OTP controller is only accessible from the secure world,
> > but the temperature calibration data stored in the OTP is exposed via
> > SMC.
> >
> > Add support for retrieving the calibration data using arm_smcc_smc().
> >
> > Add a compatible for RZ/T2H, RZ/N2H can use it as a fallback.
> >
> > Reviewed-by: John Madieu <john.madieu.xa@...renesas.com>
> > Tested-by: John Madieu <john.madieu.xa@...renesas.com>
> > Signed-off-by: Cosmin Tanislav <cosmin-gabriel.tanislav.xa@...esas.com>
> > ---
> >
> > V4:
> >  * pick up John's Reviewed-by and Tested-by
> >  * replace new macro TSU_TEMP_MASK usage with existing macro
> >    TSU_CODE_MAX
> 
> Thanks for the update!
> 
> Looks like Gmail blocked my review comments on v4 :-(
> 

That explains why there were no comments on this one!

> > index c1b586128fa6..ba13ca8cbb8c 100644
> > --- a/drivers/thermal/renesas/rzg3e_thermal.c
> > +++ b/drivers/thermal/renesas/rzg3e_thermal.c
> 
> > @@ -362,6 +366,21 @@ static int rzg3e_thermal_get_syscon_trim(struct rzg3e_thermal_priv *priv)
> >         return 0;
> >  }
> >
> > +static int rzg3e_thermal_get_smc_trim(struct rzg3e_thermal_priv *priv)
> > +{
> > +       struct arm_smccc_res local_res;
> 
> Missing #include <linux/arm-smccc.h> (on e.g. arm and riscv).
> 

Ack.

> > +
> > +       arm_smccc_smc(RZ_SIP_SVC_GET_SYSTSU, OTP_TSU_REG_ADR_TEMPLO,
> > +                     0, 0, 0, 0, 0, 0, &local_res);
> 
> Can this crash? E.g. if this SMC call is not supported by the firmware?
> 

Default TF-A firmware for RZ/N2H was missing this exact SMC call as it
was on an older version. All it did was return SMC_UNK, which is -1.
I checked the code and SMC_UNK is returned in all failure cases.
So, no crash. And -1 is caught by the 0xFFF check.

Oh, maybe I should change the 0xFFF check (the one I just moved into
rzg3e_thermal_probe()) to use the TSU_CODE_MAX macro too? I just
noticed it.

> > +       priv->trmval0 = local_res.a0 & TSU_CODE_MAX;
> > +
> > +       arm_smccc_smc(RZ_SIP_SVC_GET_SYSTSU, OTP_TSU_REG_ADR_TEMPHI,
> > +                     0, 0, 0, 0, 0, 0, &local_res);
> > +       priv->trmval1 = local_res.a0 & TSU_CODE_MAX;
> > +
> > +       return 0;
> > +}
> 
> Gr{oetje,eeting}s,
> 
>                         Geert
> 
> --
> Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@...ux-m68k.org
> 
> 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