linux-kernel - Re: [PATCH v1] arm64: dts: meson-axg: reserve memory region for Amlogic TrustOS

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Date:   Fri, 05 Aug 2022 10:03:34 +0200
From:   Jerome Brunet <jbrunet@...libre.com>
To:     Dmitry Rokosov <DDRokosov@...rdevices.ru>,
        "robh+dt@...nel.org" <robh+dt@...nel.org>,
        "krzysztof.kozlowski+dt@...aro.org" 
        <krzysztof.kozlowski+dt@...aro.org>,
        "narmstrong@...libre.com" <narmstrong@...libre.com>,
        "khilman@...libre.com" <khilman@...libre.com>,
        "martin.blumenstingl@...glemail.com" 
        <martin.blumenstingl@...glemail.com>
Cc:     "linux-arm-kernel@...ts.infradead.org" 
        <linux-arm-kernel@...ts.infradead.org>,
        "linux-amlogic@...ts.infradead.org" 
        <linux-amlogic@...ts.infradead.org>,
        "devicetree@...r.kernel.org" <devicetree@...r.kernel.org>,
        kernel <kernel@...rdevices.ru>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v1] arm64: dts: meson-axg: reserve memory region for
 Amlogic TrustOS


On Thu 04 Aug 2022 at 16:52, Dmitry Rokosov <DDRokosov@...rdevices.ru> wrote:

> For the all AXG SoC based boards, which run Amlogic vendor ATF and
> TrustOS this memory region 0x5300000-0x6300000 is reserved by BL32,
> so tag it as no-map in the kernel iomem.

This may be true for the boards you have seen so far but not all ship
with this specific AML TEE. Some don't have TEE at all, other may have
different TEE regions.

16 MB may be a significant part of the available memory on some AXG
devices. Reserving that memory on all AXG devices, regardless of what is
actually running does not seem appropriate.

I know the same has been done for other devices but I don't think we should
continue to do so. This should be set either
* per device if it is fixed
* dynamically by the bootloader depending on the ATF (which is probably better)

>
> Signed-off-by: Dmitry Rokosov <ddrokosov@...rdevices.ru>
> ---
>  arch/arm64/boot/dts/amlogic/meson-axg.dtsi | 6 ++++++
>  1 file changed, 6 insertions(+)
>
> diff --git a/arch/arm64/boot/dts/amlogic/meson-axg.dtsi b/arch/arm64/boot/dts/amlogic/meson-axg.dtsi
> index 3f5254eeb47b..1fa0d3805969 100644
> --- a/arch/arm64/boot/dts/amlogic/meson-axg.dtsi
> +++ b/arch/arm64/boot/dts/amlogic/meson-axg.dtsi
> @@ -142,6 +142,12 @@ secmon_reserved: secmon@...0000 {
>  			reg = <0x0 0x05000000 0x0 0x300000>;
>  			no-map;
>  		};
> +
> +		/* 16 MiB reserved for Amlogic Trust OS (BL32) */
> +		secos_reserved: secos@...0000 {
> +			reg = <0x0 0x05300000 0x0 0x1000000>;
> +			no-map;
> +		};
>  	};
>  
>  	scpi {