Message-ID: <CAAOTY_9dqcQdZd5x9ckE67KKh-4d_5gN9MQYDq7b4vGCWwHoDw@mail.gmail.com>
Date:   Thu, 30 Jul 2020 06:47:04 +0800
From:   Chun-Kuang Hu <chunkuang.hu@...nel.org>
To:     Neal Liu <neal.liu@...iatek.com>
Cc:     Rob Herring <robh+dt@...nel.org>,
        Matthias Brugger <matthias.bgg@...il.com>,
        devicetree@...r.kernel.org,
        wsd_upstream <wsd_upstream@...iatek.com>,
        lkml <linux-kernel@...r.kernel.org>,
        "moderated list:ARM/Mediatek SoC support" 
        <linux-mediatek@...ts.infradead.org>,
        Linux ARM <linux-arm-kernel@...ts.infradead.org>
Subject: Re: [PATCH v4 2/2] soc: mediatek: add mtk-devapc driver

Hi, Neal:

Neal Liu <neal.liu@...iatek.com> 於 2020年7月29日 週三 下午4:29寫道：
>
> 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@...iatek.com>

[snip]

> +
> +static void devapc_vio_info_print(struct mtk_devapc_context *ctx)
> +{
> +       struct mtk_devapc_vio_info *vio_info = ctx->vio_info;
> +
> +       /* Print violation information */
> +       if (vio_info->write)
> +               dev_info(ctx->dev, "Write Violation\n");
> +       else if (vio_info->read)
> +               dev_info(ctx->dev, "Read Violation\n");
> +
> +       dev_info(ctx->dev, "Vio Addr:0x%x, High:0x%x, Bus ID:0x%x, Dom ID:%x\n",
> +                vio_info->vio_addr, vio_info->vio_addr_high,
> +                vio_info->master_id, vio_info->domain_id);
> +}

devapc_vio_info_print() is small function and only called by
devapc_extract_vio_dbg(), so I would like to merge this function into
devapc_extract_vio_dbg() and you could drop struct mtk_devapc_vio_info
because its member are all local variable.

> +
> +/*
> + * devapc_extract_vio_dbg - extract full violation information after doing
> + *                          shift mechanism.
> + */
> +static void devapc_extract_vio_dbg(struct mtk_devapc_context *ctx)
> +{
> +       const struct mtk_devapc_vio_dbgs *vio_dbgs;
> +       struct mtk_devapc_vio_info *vio_info;
> +       void __iomem *vio_dbg0_reg;
> +       void __iomem *vio_dbg1_reg;
> +       u32 dbg0;
> +
> +       vio_dbg0_reg = ctx->devapc_pd_base + ctx->offset->vio_dbg0;
> +       vio_dbg1_reg = ctx->devapc_pd_base + ctx->offset->vio_dbg1;
> +
> +       vio_dbgs = ctx->vio_dbgs;
> +       vio_info = ctx->vio_info;
> +
> +       /* Starts to extract violation information */
> +       dbg0 = readl(vio_dbg0_reg);
> +       vio_info->vio_addr = readl(vio_dbg1_reg);
> +
> +       vio_info->master_id = (dbg0 & vio_dbgs->mstid.mask) >>
> +                             vio_dbgs->mstid.start;
> +       vio_info->domain_id = (dbg0 & vio_dbgs->dmnid.mask) >>
> +                             vio_dbgs->dmnid.start;
> +       vio_info->write = ((dbg0 & vio_dbgs->vio_w.mask) >>
> +                           vio_dbgs->vio_w.start) == 1;
> +       vio_info->read = ((dbg0 & vio_dbgs->vio_r.mask) >>
> +                         vio_dbgs->vio_r.start) == 1;
> +       vio_info->vio_addr_high = (dbg0 & vio_dbgs->addr_h.mask) >>
> +                                 vio_dbgs->addr_h.start;
> +
> +       devapc_vio_info_print(ctx);
> +}
> +

[snip]

> +
> +/*
> + * start_devapc - unmask slave's irq to start receiving devapc violation.
> + */
> +static void start_devapc(struct mtk_devapc_context *ctx)
> +{
> +       u32 vio_idx;
> +
> +       for (vio_idx = 0; vio_idx < ctx->vio_idx_num; vio_idx++)
> +               mask_module_irq(ctx, vio_idx, false);

Are these bits default true? If they are default false, you need not
to setup it to false again.

> +}
> +

[snip]

> diff --git a/drivers/soc/mediatek/mtk-devapc.h b/drivers/soc/mediatek/mtk-devapc.h
> new file mode 100644
> index 0000000..7bd7e66
> --- /dev/null
> +++ b/drivers/soc/mediatek/mtk-devapc.h
> @@ -0,0 +1,54 @@
> +/* SPDX-License-Identifier: GPL-2.0 */
> +/*
> + * Copyright (C) 2020 MediaTek Inc.
> + */
> +
> +#ifndef __MTK_DEVAPC_H__
> +#define __MTK_DEVAPC_H__
> +
> +#define VIO_MOD_TO_REG_IND(m)  ((m) / 32)
> +#define VIO_MOD_TO_REG_OFF(m)  ((m) % 32)
> +
> +struct mtk_devapc_pd_offset {
> +       u32 vio_mask;
> +       u32 vio_sta;
> +       u32 vio_dbg0;
> +       u32 vio_dbg1;
> +       u32 apc_con;
> +       u32 vio_shift_sta;
> +       u32 vio_shift_sel;
> +       u32 vio_shift_con;
> +};
> +
> +struct mtk_devapc_vio_dbgs_desc {
> +       u32 mask;
> +       u32 start;
> +};
> +
> +struct mtk_devapc_vio_dbgs {
> +       struct mtk_devapc_vio_dbgs_desc mstid;
> +       struct mtk_devapc_vio_dbgs_desc dmnid;
> +       struct mtk_devapc_vio_dbgs_desc vio_w;
> +       struct mtk_devapc_vio_dbgs_desc vio_r;
> +       struct mtk_devapc_vio_dbgs_desc addr_h;
> +};
> +
> +struct mtk_devapc_vio_info {
> +       bool read;
> +       bool write;
> +       u32 vio_addr;
> +       u32 vio_addr_high;
> +       u32 master_id;
> +       u32 domain_id;
> +};
> +
> +struct mtk_devapc_context {
> +       struct device *dev;
> +       u32 vio_idx_num;
> +       void __iomem *devapc_pd_base;
> +       struct mtk_devapc_vio_info *vio_info;
> +       const struct mtk_devapc_pd_offset *offset;
> +       const struct mtk_devapc_vio_dbgs *vio_dbgs;
> +};
> +
> +#endif /* __MTK_DEVAPC_H__ */

Data in this header file is only used in mtk-devapc.c and mtk-devapc.c
is a small file, so I think it's better to move data in header file
into .c file to make code simpler.

Regards,
Chun-Kuang.

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