iommu/mediatek: Lookup phandle to retrieve syscon to infracfg

This driver will get support for more SoCs and the list of infracfg
compatibles is expected to grow: in order to prevent getting this
situation out of control and see a long list of compatible strings,
add support to retrieve a handle to infracfg's regmap through a
new "mediatek,infracfg" phandle.

In order to keep retrocompatibility with older devicetrees, the old
way is kept in place.

Signed-off-by: AngeloGioacchino Del Regno <angelogioacchino.delregno@collabora.com>
Reviewed-by: Miles Chen <miles.chen@mediatek.com>
Reviewed-by: Yong Wu <yong.wu@mediatek.com>
Reviewed-by: Matthias Brugger <matthias.bgg@gmail.com>
Link: https://lore.kernel.org/r/20220616110830.26037-3-angelogioacchino.delregno@collabora.com
Signed-off-by: Joerg Roedel <jroedel@suse.de>

diff --git a/drivers/iommu/mtk_iommu.c b/drivers/iommu/mtk_iommu.c
index bb9dd92c9898d3ea34ecec811937c8311b663762..90685946fcbe30537b1f09006e60d664527b8f59 100644 (file)
--- a/drivers/iommu/mtk_iommu.c
+++ b/drivers/iommu/mtk_iommu.c
@@ -1140,22 +1140,32 @@ static int mtk_iommu_probe(struct platform_device *pdev)
        data->protect_base = ALIGN(virt_to_phys(protect), MTK_PROTECT_PA_ALIGN);
 
        if (MTK_IOMMU_HAS_FLAG(data->plat_data, HAS_4GB_MODE)) {
-               switch (data->plat_data->m4u_plat) {
-               case M4U_MT2712:
-                       p = "mediatek,mt2712-infracfg";
-                       break;
-               case M4U_MT8173:
-                       p = "mediatek,mt8173-infracfg";
-                       break;
-               default:
-                       p = NULL;
+               infracfg = syscon_regmap_lookup_by_phandle(dev->of_node, "mediatek,infracfg");
+               if (IS_ERR(infracfg)) {
+                       /*
+                        * Legacy devicetrees will not specify a phandle to
+                        * mediatek,infracfg: in that case, we use the older
+                        * way to retrieve a syscon to infra.
+                        *
+                        * This is for retrocompatibility purposes only, hence
+                        * no more compatibles shall be added to this.
+                        */
+                       switch (data->plat_data->m4u_plat) {
+                       case M4U_MT2712:
+                               p = "mediatek,mt2712-infracfg";
+                               break;
+                       case M4U_MT8173:
+                               p = "mediatek,mt8173-infracfg";
+                               break;
+                       default:
+                               p = NULL;
+                       }
+
+                       infracfg = syscon_regmap_lookup_by_compatible(p);
+                       if (IS_ERR(infracfg))
+                               return PTR_ERR(infracfg);
                }
 
-               infracfg = syscon_regmap_lookup_by_compatible(p);
-
-               if (IS_ERR(infracfg))
-                       return PTR_ERR(infracfg);
-
                ret = regmap_read(infracfg, REG_INFRA_MISC, &val);
                if (ret)
                        return ret;