linux-kernel - [PATCH 4/8] iommu: mtk_iommu: Lookup phandle to retrieve syscon to pericfg

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Date:   Tue, 17 May 2022 15:21:03 +0200
From:   AngeloGioacchino Del Regno 
        <angelogioacchino.delregno@...labora.com>
To:     yong.wu@...iatek.com
Cc:     joro@...tes.org, will@...nel.org, robh+dt@...nel.org,
        krzysztof.kozlowski+dt@...aro.org, matthias.bgg@...il.com,
        iommu@...ts.linux-foundation.org,
        linux-mediatek@...ts.infradead.org, devicetree@...r.kernel.org,
        linux-kernel@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
        AngeloGioacchino Del Regno 
        <angelogioacchino.delregno@...labora.com>
Subject: [PATCH 4/8] iommu: mtk_iommu: Lookup phandle to retrieve syscon to pericfg

On some SoCs (of which only MT8195 is supported at the time of writing),
the "R" and "W" (I/O) enable bits for the IOMMUs are in the pericfg_ao
register space and not in the IOMMU space: as it happened already with
infracfg, it is expected that this list will grow.

Instead of specifying pericfg compatibles on a per-SoC basis, following
what was done with infracfg, let's lookup the syscon by phandle instead.
Also following the previous infracfg change, add a warning for outdated
devicetrees, in hope that the user will take action.

Signed-off-by: AngeloGioacchino Del Regno <angelogioacchino.delregno@...labora.com>
---
 drivers/iommu/mtk_iommu.c | 26 ++++++++++++++++----------
 1 file changed, 16 insertions(+), 10 deletions(-)

diff --git a/drivers/iommu/mtk_iommu.c b/drivers/iommu/mtk_iommu.c
index cfaaa98d2b50..c7e2d836199e 100644
--- a/drivers/iommu/mtk_iommu.c
+++ b/drivers/iommu/mtk_iommu.c
@@ -138,6 +138,8 @@
 /* PM and clock always on. e.g. infra iommu */
 #define PM_CLK_AO			BIT(15)
 #define IFA_IOMMU_PCIE_SUPPORT		BIT(16)
+/* IOMMU I/O (r/w) is enabled using PERICFG_IOMMU_1 register */
+#define HAS_PERI_IOMMU1_REG		BIT(17)
 
 #define MTK_IOMMU_HAS_FLAG_MASK(pdata, _x, mask)	\
 				((((pdata)->flags) & (mask)) == (_x))
@@ -187,7 +189,6 @@ struct mtk_iommu_plat_data {
 	u32			flags;
 	u32			inv_sel_reg;
 
-	char			*pericfg_comp_str;
 	struct list_head	*hw_list;
 	unsigned int		iova_region_nr;
 	const struct mtk_iommu_iova_region	*iova_region;
@@ -1214,14 +1215,19 @@ static int mtk_iommu_probe(struct platform_device *pdev)
 			goto out_runtime_disable;
 		}
 	} else if (MTK_IOMMU_IS_TYPE(data->plat_data, MTK_IOMMU_TYPE_INFRA) &&
-		   data->plat_data->pericfg_comp_str) {
-		infracfg = syscon_regmap_lookup_by_compatible(data->plat_data->pericfg_comp_str);
-		if (IS_ERR(infracfg)) {
-			ret = PTR_ERR(infracfg);
-			goto out_runtime_disable;
-		}
+		   MTK_IOMMU_HAS_FLAG(data->plat_data, HAS_PERI_IOMMU1_REG)) {
+		data->pericfg = syscon_regmap_lookup_by_phandle(dev->of_node, "mediatek,pericfg");
+		if (IS_ERR(data->pericfg)) {
+			dev_warn(dev, "Cannot find phandle to mediatek,pericfg:"
+				      " Please update your devicetree.\n");
 
-		data->pericfg = infracfg;
+			p = "mediatek,mt8195-pericfg_ao";
+			data->pericfg = syscon_regmap_lookup_by_compatible(p);
+			if (IS_ERR(data->pericfg)) {
+				ret = PTR_ERR(data->pericfg);
+				goto out_runtime_disable;
+			}
+		}
 	}
 
 	platform_set_drvdata(pdev, data);
@@ -1480,8 +1486,8 @@ static const struct mtk_iommu_plat_data mt8192_data = {
 static const struct mtk_iommu_plat_data mt8195_data_infra = {
 	.m4u_plat	  = M4U_MT8195,
 	.flags            = WR_THROT_EN | DCM_DISABLE | STD_AXI_MODE | PM_CLK_AO |
-			    MTK_IOMMU_TYPE_INFRA | IFA_IOMMU_PCIE_SUPPORT,
-	.pericfg_comp_str = "mediatek,mt8195-pericfg_ao",
+			    HAS_PERI_IOMMU1_REG | MTK_IOMMU_TYPE_INFRA |
+			    IFA_IOMMU_PCIE_SUPPORT,
 	.inv_sel_reg      = REG_MMU_INV_SEL_GEN2,
 	.banks_num	  = 5,
 	.banks_enable     = {true, false, false, false, true},
-- 
2.35.1