iommu/mediatek: Add a flag for iova 34bits case

Add a HW flag for if the HW support 34bit IOVA. the previous SoC
still use 32bit. normally the lvl1 pgtable size is 16KB when ias == 32.
if ias == 34, lvl1 pgtable size is 16KB * 4. The purpose of this patch
is to save 16KB*3 continuous memory for the previous SoC.

Signed-off-by: Yong Wu <yong.wu@mediatek.com>
Reviewed-by: Tomasz Figa <tfiga@chromium.org>
Link: https://lore.kernel.org/r/20210111111914.22211-15-yong.wu@mediatek.com
Signed-off-by: Will Deacon <will@kernel.org>

drivers/iommu/mtk_iommu.c

@@ -112,6 +112,7 @@
 #define HAS_SUB_COMM			BIT(5)
 #define WR_THROT_EN			BIT(6)
 #define HAS_LEGACY_IVRP_PADDR		BIT(7)
+#define IOVA_34_EN			BIT(8)
 
 #define MTK_IOMMU_HAS_FLAG(pdata, _x) \
 		((((pdata)->flags) & (_x)) == (_x))
@@ -299,7 +300,7 @@ static int mtk_iommu_domain_finalise(struct mtk_iommu_domain *dom)
 			IO_PGTABLE_QUIRK_NO_PERMS |
 			IO_PGTABLE_QUIRK_ARM_MTK_EXT,
 		.pgsize_bitmap = mtk_iommu_ops.pgsize_bitmap,
-		.ias = 32,
+		.ias = MTK_IOMMU_HAS_FLAG(data->plat_data, IOVA_34_EN) ? 34 : 32,
 		.oas = 35,
 		.iommu_dev = data->dev,
 	};