Re: [PATCH 2/2] iommu: mtk_iommu: Add support for MT6795 Helio X10 M4Us

[Yong Wu <yong.wu@mediatek.com>]

On Fri, 2022-05-13 at 17:14 +0200, AngeloGioacchino Del Regno wrote:
> Add support for the M4Us found in the MT6795 Helio X10 SoC.
> 
> Signed-off-by: AngeloGioacchino Del Regno <
> angelogioacchino.delregno@collabora.com>
> ---
>  drivers/iommu/mtk_iommu.c | 20 +++++++++++++++++++-
>  1 file changed, 19 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/iommu/mtk_iommu.c b/drivers/iommu/mtk_iommu.c
> index 71b2ace74cd6..3d802dd3f377 100644
> --- a/drivers/iommu/mtk_iommu.c
> +++ b/drivers/iommu/mtk_iommu.c
> @@ -157,6 +157,7 @@
>  enum mtk_iommu_plat {
>  	M4U_MT2712,
>  	M4U_MT6779,
> +	M4U_MT6795,
>  	M4U_MT8167,
>  	M4U_MT8173,
>  	M4U_MT8183,
> @@ -953,7 +954,8 @@ static int mtk_iommu_hw_init(const struct
> mtk_iommu_data *data, unsigned int ban
>  	 * Global control settings are in bank0. May re-init these
> global registers
>  	 * since no sure if there is bank0 consumers.
>  	 */
> -	if (data->plat_data->m4u_plat == M4U_MT8173) {
> +	if (data->plat_data->m4u_plat == M4U_MT6795 ||
> +	    data->plat_data->m4u_plat == M4U_MT8173) {
>  		regval = F_MMU_PREFETCH_RT_REPLACE_MOD |
>  			 F_MMU_TF_PROT_TO_PROGRAM_ADDR_MT8173;
>  	} else {
> @@ -1138,6 +1140,9 @@ static int mtk_iommu_probe(struct
> platform_device *pdev)
>  		case M4U_MT2712:
>  			p = "mediatek,mt2712-infracfg";
>  			break;
> +		case M4U_MT6795:
> +			p = "mediatek,mt6795-infracfg";
> +			break;
>  		case M4U_MT8173:
>  			p = "mediatek,mt8173-infracfg";
>  			break;
> @@ -1404,6 +1409,18 @@ static const struct mtk_iommu_plat_data
> mt6779_data = {
>  	.larbid_remap  = {{0}, {1}, {2}, {3}, {5}, {7, 8}, {10}, {9}},
>  };
>  
> +static const struct mtk_iommu_plat_data mt6795_data = {
> +	.m4u_plat     = M4U_MT6795,
> +	.flags	      = HAS_4GB_MODE | HAS_BCLK | RESET_AXI |
> +			HAS_LEGACY_IVRP_PADDR | MTK_IOMMU_TYPE_MM,
> +	.inv_sel_reg  = REG_MMU_INV_SEL_GEN1,
> +	.banks_num    = 1,
> +	.banks_enable = {true},
> +	.iova_region  = single_domain,
> +	.iova_region_nr = ARRAY_SIZE(single_domain),
> +	.larbid_remap = {{0}, {1}, {2}, {3}, {4}}, /* Linear mapping.
> */
> +};

This is nearly same with mt8173_data. mt8173 has one more larb than
mt6795, its larbid_remap is also ok for mt6795.

thus it looks we could use mt8173 as the backward compatible.
    compatible = "mediatek,mt6795-m4u",
                 "mediatek,mt8173-m4u";

After this, the only thing is about "mediatek,mt6795-infracfg". we have
to try again with mediatek,mt6795-infracfg after mediatek,mt8173-
infracfg fail. I think we should allow the backward case in 4GB mode
judgment if we have.

What's your opinion? or some other suggestion?
Thanks.

> +
>  static const struct mtk_iommu_plat_data mt8167_data = {
>  	.m4u_plat     = M4U_MT8167,
>  	.flags        = RESET_AXI | HAS_LEGACY_IVRP_PADDR |
> MTK_IOMMU_TYPE_MM,
> @@ -1515,6 +1532,7 @@ static const struct mtk_iommu_plat_data
> mt8195_data_vpp = {
>  static const struct of_device_id mtk_iommu_of_ids[] = {
>  	{ .compatible = "mediatek,mt2712-m4u", .data = &mt2712_data},
>  	{ .compatible = "mediatek,mt6779-m4u", .data = &mt6779_data},
> +	{ .compatible = "mediatek,mt6795-m4u", .data = &mt6795_data},
>  	{ .compatible = "mediatek,mt8167-m4u", .data = &mt8167_data},
>  	{ .compatible = "mediatek,mt8173-m4u", .data = &mt8173_data},
>  	{ .compatible = "mediatek,mt8183-m4u", .data = &mt8183_data},