linux-kernel - Re: [PATCH v3 2/3] iommu/mediatek: Add enable IOMMU SMC command for INFRA master

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Message-ID: <3a0ac49f-2245-fb64-aa60-e3b1a1d4afcd@collabora.com>
Date:   Tue, 20 Sep 2022 11:01:56 +0200
From:   AngeloGioacchino Del Regno 
        <angelogioacchino.delregno@...labora.com>
To:     "Chengci.Xu" <chengci.xu@...iatek.com>,
        Yong Wu <yong.wu@...iatek.com>, Joerg Roedel <joro@...tes.org>,
        Will Deacon <will@...nel.org>,
        Robin Murphy <robin.murphy@....com>,
        Rob Herring <robh+dt@...nel.org>,
        Krzysztof Kozlowski <krzysztof.kozlowski+dt@...aro.org>,
        Matthias Brugger <matthias.bgg@...il.com>
Cc:     iommu@...ts.linux.dev, linux-mediatek@...ts.infradead.org,
        devicetree@...r.kernel.org, linux-kernel@...r.kernel.org,
        linux-arm-kernel@...ts.infradead.org,
        Project_Global_Chrome_Upstream_Group@...iatek.com
Subject: Re: [PATCH v3 2/3] iommu/mediatek: Add enable IOMMU SMC command for
 INFRA master

Il 19/09/22 10:26, Chengci.Xu ha scritto:
> The register which can enable IOMMU for INFRA master should be setted
> in secure world for security concerns. Therefore, we add a SMC command
> for INFRA master to enable/disable INFRA IOMMU in ATF. This function is
> prepared for MT8188.
> 
> Signed-off-by: Chengci.Xu <chengci.xu@...iatek.com>
> ---
>   drivers/iommu/mtk_iommu.c  | 21 +++++++++++++++++++--
>   include/soc/mediatek/smi.h |  1 +
>   2 files changed, 20 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/iommu/mtk_iommu.c b/drivers/iommu/mtk_iommu.c
> index 552e4eb8c610..8b8a289bab2c 100644
> --- a/drivers/iommu/mtk_iommu.c
> +++ b/drivers/iommu/mtk_iommu.c
> @@ -3,6 +3,7 @@
>    * Copyright (c) 2015-2016 MediaTek Inc.
>    * Author: Yong Wu <yong.wu@...iatek.com>
>    */
> +#include <linux/arm-smccc.h>
>   #include <linux/bitfield.h>
>   #include <linux/bug.h>
>   #include <linux/clk.h>
> @@ -28,6 +29,7 @@
>   #include <linux/slab.h>
>   #include <linux/spinlock.h>
>   #include <linux/soc/mediatek/infracfg.h>
> +#include <linux/soc/mediatek/mtk_sip_svc.h>
>   #include <asm/barrier.h>
>   #include <soc/mediatek/smi.h>
>   
> @@ -138,6 +140,7 @@
>   #define PM_CLK_AO			BIT(15)
>   #define IFA_IOMMU_PCIE_SUPPORT		BIT(16)
>   #define PGTABLE_PA_35_EN		BIT(17)
> +#define CFG_IFA_MASTER_IN_ATF		BIT(18)
>   
>   #define MTK_IOMMU_HAS_FLAG_MASK(pdata, _x, mask)	\
>   				((((pdata)->flags) & (mask)) == (_x))
> @@ -553,7 +556,20 @@ static int mtk_iommu_config(struct mtk_iommu_data *data, struct device *dev,
>   				larb_mmu->mmu |= MTK_SMI_MMU_EN(portid);
>   			else
>   				larb_mmu->mmu &= ~MTK_SMI_MMU_EN(portid);
> -		} else if (MTK_IOMMU_IS_TYPE(data->plat_data, MTK_IOMMU_TYPE_INFRA)) {
> +		} else if (MTK_IOMMU_IS_TYPE(data->plat_data, MTK_IOMMU_TYPE_INFRA) &&
> +			   MTK_IOMMU_HAS_FLAG(data->plat_data, CFG_IFA_MASTER_IN_ATF)) {
> +			struct arm_smccc_res res;
> +
> +			arm_smccc_smc(MTK_SIP_KERNEL_IOMMU_CONTROL,
> +				      IOMMU_ATF_CMD_CONFIG_INFRA_IOMMU,
> +				      portid, enable, 0, 0, 0, 0, &res);
> +			if (res.a0 != 0) {
> +				dev_err(dev, "%s iommu(%s) inframaster %d fail(%ld).\n",
> +					enable ? "enable" : "disable",
> +					dev_name(data->dev), portid, res.a0);
> +				ret = -EINVAL;
> +			}
> +		} else {

This one is opening a big window for future mistakes.

I think that the only way that you have to do this is...

	} else if (MTK_IOMMU_IS_TYPE(data->plat_data, MTK_IOMMU_TYPE_INFRA)) {
		if (MTK_IOMMU_HAS_FLAG(data->plat_data, CFG_IFA_MASTER_IN_ATF)) {
			arm_smcc_smc ....
		} else {
			peri_mmuen_msk ....
		}
	}

Otherwise, to reduce indentation, you'd have to do something like...

static int mtk_iommu_config_one(struct mtk_iommu_data *data, struct device *dev,
				bool enable, u32 regionid, u32 larbid, u32 portid)
{
	struct mtk_smi_larb_iommu *larb_mmu;
	............
}

static int mtk_iommu_config(struct .............)
{
	vars, etc....

	for (i = 0; i < fwspec->num_ids; ++i)
		mtk_iommu_config_one(data, dev, enable, regionid,
				     MTK_M4U_TO_LARB(...), MTK_M4U_TO_PORT(...));
}


or....

static int mtk_iommu_config_one_infra(struct ....)
{
	if (is atf) ....
	else ....
}

Your choice.

Regards,
Angelo