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Message-ID: <aFCJ9IuzC1Rx2atk@google.com>
Date: Mon, 16 Jun 2025 21:17:40 +0000
From: Pranjal Shrivastava <praan@...gle.com>
To: Xueqi Zhang <xueqi.zhang@...iatek.com>
Cc: Yong Wu <yong.wu@...iatek.com>, Will Deacon <will@...nel.org>,
Robin Murphy <robin.murphy@....com>, Joerg Roedel <joro@...tes.org>,
Rob Herring <robh@...nel.org>,
Krzysztof Kozlowski <krzk+dt@...nel.org>,
Conor Dooley <conor+dt@...nel.org>,
Matthias Brugger <matthias.bgg@...il.com>,
AngeloGioacchino Del Regno <angelogioacchino.delregno@...labora.com>,
Project_Global_Chrome_Upstream_Group@...iatek.com,
Ning li <ning.li@...iatek.com>, linux-mediatek@...ts.infradead.org,
linux-kernel@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
devicetree@...r.kernel.org, iommu@...ts.linux.dev
Subject: Re: [RFC PATCH 2/8] iommu/arm-smmu-v3: Add SMMU implementation
On Mon, Jun 16, 2025 at 10:56:08AM +0800, Xueqi Zhang wrote:
> Mediatek has its own implementation for wrapper interrupts and
> power management.So add SMMU implementation when smmu device probe.
>
> Signed-off-by: Xueqi Zhang <xueqi.zhang@...iatek.com>
> ---
> drivers/iommu/arm/Kconfig | 7 +++++++
> drivers/iommu/arm/arm-smmu-v3/Makefile | 3 ++-
> drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3-impl.c | 16 ++++++++++++++++
> .../iommu/arm/arm-smmu-v3/arm-smmu-v3-mediatek.c | 13 +++++++++++++
> drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c | 3 +++
> drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.h | 4 ++++
> 6 files changed, 45 insertions(+), 1 deletion(-)
> create mode 100644 drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3-impl.c
> create mode 100644 drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3-mediatek.c
>
> diff --git a/drivers/iommu/arm/Kconfig b/drivers/iommu/arm/Kconfig
> index ef42bbe07dbe..a7f98fd0f2bf 100644
> --- a/drivers/iommu/arm/Kconfig
> +++ b/drivers/iommu/arm/Kconfig
> @@ -88,6 +88,13 @@ config ARM_SMMU_V3
> the ARM SMMUv3 architecture.
>
> if ARM_SMMU_V3
> +config ARM_SMMU_V3_MEDIATEK
> + bool "ARM Ltd. System MMU Version 3 (SMMUv3) MediaTek Support"
> + depends on ARM_SMMU_V3 && ARCH_MEDIATEK
> + help
> + When running on a MediaTek platform that has the custom variant
> + of the ARM SMMUv3, this needs to be built into the SMMU driver.
> +
> config ARM_SMMU_V3_SVA
> bool "Shared Virtual Addressing support for the ARM SMMUv3"
> select IOMMU_SVA
> diff --git a/drivers/iommu/arm/arm-smmu-v3/Makefile b/drivers/iommu/arm/arm-smmu-v3/Makefile
> index 493a659cc66b..0670065d6e9a 100644
> --- a/drivers/iommu/arm/arm-smmu-v3/Makefile
> +++ b/drivers/iommu/arm/arm-smmu-v3/Makefile
> @@ -1,7 +1,8 @@
> # SPDX-License-Identifier: GPL-2.0
> obj-$(CONFIG_ARM_SMMU_V3) += arm_smmu_v3.o
> -arm_smmu_v3-y := arm-smmu-v3.o
> +arm_smmu_v3-y := arm-smmu-v3.o arm-smmu-v3-impl.o
> arm_smmu_v3-$(CONFIG_ARM_SMMU_V3_IOMMUFD) += arm-smmu-v3-iommufd.o
> +arm_smmu_v3-$(CONFIG_ARM_SMMU_V3_MEDIATEK) += arm-smmu-v3-mediatek.o
> arm_smmu_v3-$(CONFIG_ARM_SMMU_V3_SVA) += arm-smmu-v3-sva.o
> arm_smmu_v3-$(CONFIG_TEGRA241_CMDQV) += tegra241-cmdqv.o
>
> diff --git a/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3-impl.c b/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3-impl.c
> new file mode 100644
> index 000000000000..d39587b965ef
> --- /dev/null
> +++ b/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3-impl.c
> @@ -0,0 +1,16 @@
> +// SPDX-License-Identifier: GPL-2.0-only
> +/*
> + * Copyright (c) 2025 MediaTek Inc.
> + * Author: Ning li <ning.li@...iatek.com>
> + * Author: Xueqi Zhang <xueqi.zhang@...iatek.com>
> + */
> +
> +#include "arm-smmu-v3.h"
> +
> +struct arm_smmu_device *arm_smmu_v3_impl_init(struct arm_smmu_device *smmu)
> +{
> +#if IS_ENABLED(CONFIG_ARM_SMMU_V3_MEDIATEK)
> + smmu = arm_smmu_v3_impl_mtk_init(smmu);
> +#endif
> + return smmu;
> +}
> diff --git a/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3-mediatek.c b/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3-mediatek.c
> new file mode 100644
> index 000000000000..381268968185
> --- /dev/null
> +++ b/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3-mediatek.c
> @@ -0,0 +1,13 @@
> +// SPDX-License-Identifier: GPL-2.0-only
> +/*
> + * Copyright (c) 2025 MediaTek Inc.
> + * Author: Ning li <ning.li@...iatek.com>
> + * Author: Xueqi Zhang <xueqi.zhang@...iatek.com>
> + */
> +
> +#include "arm-smmu-v3.h"
> +
> +struct arm_smmu_device *arm_smmu_v3_impl_mtk_init(struct arm_smmu_device *smmu)
> +{
> + return NULL;
> +}
> diff --git a/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c b/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c
> index 10cc6dc26b7b..d36124a6bb54 100644
> --- a/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c
> +++ b/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c
> @@ -4754,6 +4754,9 @@ static int arm_smmu_device_probe(struct platform_device *pdev)
> }
> ioaddr = res->start;
>
> + smmu = arm_smmu_v3_impl_init(smmu);
> + if (IS_ERR(smmu))
> + return PTR_ERR(smmu);
I'd suggest adding ops to struct arm_smmu_impl_ops and use them. Please
see how Nvidia's implementation makes use of `arm_smmu_impl_probe`,
maybe we could improve that function to handle mtk smmu as well.
> /*
> * Don't map the IMPLEMENTATION DEFINED regions, since they may contain
> * the PMCG registers which are reserved by the PMU driver.
> diff --git a/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.h b/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.h
> index ea41d790463e..99eeb6143c49 100644
> --- a/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.h
> +++ b/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.h
> @@ -998,6 +998,10 @@ int arm_smmu_cmdq_issue_cmdlist(struct arm_smmu_device *smmu,
> struct arm_smmu_cmdq *cmdq, u64 *cmds, int n,
> bool sync);
>
> +struct arm_smmu_device *arm_smmu_v3_impl_init(struct arm_smmu_device *smmu);
> +#if IS_ENABLED(CONFIG_ARM_SMMU_V3_MEDIATEK)
> +struct arm_smmu_device *arm_smmu_v3_impl_mtk_init(struct arm_smmu_device *smmu);
> +#endif
We'd prefer to avoid implementation-specific #if CONFIG_* across the
driver as much as possible.
> #ifdef CONFIG_ARM_SMMU_V3_SVA
> bool arm_smmu_sva_supported(struct arm_smmu_device *smmu);
> void arm_smmu_sva_notifier_synchronize(void);
> --
> 2.46.0
Thanks,
Praan
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