linux-kernel - Re: [v2,2/3] thermal: mediatek: Add LVTS drivers for SoC theraml zones

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Date:   Sun, 14 Feb 2021 09:58:48 +0800
From:   Nicolas Boichat <drinkcat@...omium.org>
To:     Michael Kao <michael.kao@...iatek.com>
Cc:     Fan Chen <fan.chen@...iatek.com>, Zhang Rui <rui.zhang@...el.com>,
        Daniel Lezcano <daniel.lezcano@...aro.org>,
        "open list:THERMAL" <linux-pm@...r.kernel.org>,
        srv_heupstream <srv_heupstream@...iatek.com>,
        Mark Rutland <mark.rutland@....com>,
        Devicetree List <devicetree@...r.kernel.org>,
        lkml <linux-kernel@...r.kernel.org>,
        Eduardo Valentin <edubezval@...il.com>,
        Rob Herring <robh+dt@...nel.org>,
        "moderated list:ARM/Mediatek SoC support" 
        <linux-mediatek@...ts.infradead.org>,
        Hsin-Yi Wang <hsinyi@...omium.org>,
        Matthias Brugger <matthias.bgg@...il.com>,
        linux-arm Mailing List <linux-arm-kernel@...ts.infradead.org>
Subject: Re: [v2,2/3] thermal: mediatek: Add LVTS drivers for SoC theraml zones

On Fri, Jan 29, 2021 at 5:40 PM Michael Kao <michael.kao@...iatek.com> wrote:
>
> Add a LVTS (Low voltage thermal sensor) driver to report junction
> temperatures in Mediatek SoC and register the maximum temperature
> of sensors and each sensor as a thermal zone.
>
> Signed-off-by: Yu-Chia Chang <ethan.chang@...iatek.com>
> Signed-off-by: Michael Kao <michael.kao@...iatek.com>
> ---
>  drivers/thermal/mediatek/Kconfig         |   10 +
>  drivers/thermal/mediatek/Makefile        |    1 +
>  drivers/thermal/mediatek/soc_temp_lvts.c | 1287 ++++++++++++++++++++++
>  drivers/thermal/mediatek/soc_temp_lvts.h |  312 ++++++
>  4 files changed, 1610 insertions(+)
>  create mode 100644 drivers/thermal/mediatek/soc_temp_lvts.c
>  create mode 100644 drivers/thermal/mediatek/soc_temp_lvts.h
>
> [snip]
> diff --git a/drivers/thermal/mediatek/Makefile b/drivers/thermal/mediatek/Makefile
> index f75313ddce5e..16ce166e5916 100644
> --- a/drivers/thermal/mediatek/Makefile
> +++ b/drivers/thermal/mediatek/Makefile
> @@ -1 +1,2 @@
>  obj-$(CONFIG_MTK_SOC_THERMAL)  += soc_temp.o
> +obj-$(CONFIG_MTK_SOC_THERMAL_LVTS)     += soc_temp_lvts.o
> diff --git a/drivers/thermal/mediatek/soc_temp_lvts.c b/drivers/thermal/mediatek/soc_temp_lvts.c
> new file mode 100644
> index 000000000000..b56c2cd3cb39
> --- /dev/null
> +++ b/drivers/thermal/mediatek/soc_temp_lvts.c
> @@ -0,0 +1,1287 @@
> [snip]
> +
> +static unsigned int lvts_temp_to_raw(struct formula_coeff *co, int temp)
> +{
> +       unsigned int msr_raw;
> +
> +       msr_raw = ((long long)((co->golden_temp * 500 + co->b - temp)) << 14)
> +               / (-1 * co->a);

This fails to build test on arm (32-bit):
ERROR: "__aeabi_ldivmod" [drivers/thermal/mediatek/soc_temp_lvts.ko] undefined!

Recommend using div_s64:
   msr_raw = div_s64((s64)((co->golden_temp * 500 + co->b - temp)) << 14,
                     -1 * co->a);

> +
> +       return msr_raw;
> +}
> [snip]