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From:   Chun-Kuang Hu <chunkuang.hu@kernel.org>
Date:   Sat, 3 Oct 2020 00:24:11 +0800
Message-ID: <CAAOTY_-KTs6-5ZpzAWs0Yn-R3AJc8tRhDyKbp8bx60EJtfu-_Q@mail.gmail.com>
Subject: Re: [PATCH v7 2/2] soc: mediatek: add mt6779 devapc driver
To:     Neal Liu <neal.liu@mediatek.com>
Cc:     Rob Herring <robh+dt@kernel.org>,
        Matthias Brugger <matthias.bgg@gmail.com>,
        Chun-Kuang Hu <chunkuang.hu@kernel.org>,
        DTML <devicetree@vger.kernel.org>,
        Linux ARM <linux-arm-kernel@lists.infradead.org>,
        "moderated list:ARM/Mediatek SoC support" 
        <linux-mediatek@lists.infradead.org>,
        lkml <linux-kernel@vger.kernel.org>,
        wsd_upstream <wsd_upstream@mediatek.com>
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Hi, Neal:

Neal Liu <neal.liu@mediatek.com> =E6=96=BC 2020=E5=B9=B48=E6=9C=8827=E6=97=
=A5 =E9=80=B1=E5=9B=9B =E4=B8=8A=E5=8D=8811:07=E5=AF=AB=E9=81=93=EF=BC=9A
>
> MediaTek bus fabric provides TrustZone security support and data
> protection to prevent slaves from being accessed by unexpected
> masters.
> The security violation is logged and sent to the processor for
> further analysis or countermeasures.
>
> Any occurrence of security violation would raise an interrupt, and
> it will be handled by mtk-devapc driver. The violation
> information is printed in order to find the murderer.
>
> Signed-off-by: Neal Liu <neal.liu@mediatek.com>
> ---
>  drivers/soc/mediatek/Kconfig      |    9 ++
>  drivers/soc/mediatek/Makefile     |    1 +
>  drivers/soc/mediatek/mtk-devapc.c |  305 +++++++++++++++++++++++++++++++=
++++++
>  3 files changed, 315 insertions(+)
>  create mode 100644 drivers/soc/mediatek/mtk-devapc.c
>

[snip]

> +
> +static int mtk_devapc_probe(struct platform_device *pdev)
> +{
> +       struct device_node *node =3D pdev->dev.of_node;
> +       struct mtk_devapc_context *ctx;
> +       u32 devapc_irq;
> +       int ret;
> +
> +       if (IS_ERR(node))
> +               return -ENODEV;
> +
> +       ctx =3D devm_kzalloc(&pdev->dev, sizeof(*ctx), GFP_KERNEL);
> +       if (!ctx)
> +               return -ENOMEM;
> +
> +       ctx->data =3D of_device_get_match_data(&pdev->dev);
> +       ctx->dev =3D &pdev->dev;
> +
> +       ctx->infra_base =3D of_iomap(node, 0);
> +       if (!ctx->infra_base)
> +               return -EINVAL;
> +
> +       devapc_irq =3D irq_of_parse_and_map(node, 0);
> +       if (!devapc_irq)
> +               return -EINVAL;
> +
> +       ctx->infra_clk =3D devm_clk_get(&pdev->dev, "devapc-infra-clock")=
;
> +       if (IS_ERR(ctx->infra_clk))
> +               return -EINVAL;
> +
> +       if (clk_prepare_enable(ctx->infra_clk))
> +               return -EINVAL;

What would happen if you do not enable this clock? I think this
hardware is already initialized in trust zone.

Regards,
Chun-Kuang.

> +
> +       ret =3D devm_request_irq(&pdev->dev, devapc_irq,
> +                              (irq_handler_t)devapc_violation_irq,
> +                              IRQF_TRIGGER_NONE, "devapc", ctx);
> +       if (ret) {
> +               clk_disable_unprepare(ctx->infra_clk);
> +               return ret;
> +       }
> +
> +       platform_set_drvdata(pdev, ctx);
> +
> +       start_devapc(ctx);
> +
> +       return 0;
> +}
> +