Apple's DART iommu uses a pagetable format that shares some
similarities with the ones already implemented by io-pgtable.c.
Add a new format variant to support the required differences
so that we don't have to duplicate the pagetable handling code.

Signed-off-by: Sven Peter <redacted>
---
 drivers/iommu/io-pgtable-arm.c | 59 ++++++++++++++++++++++++++++++++++
 drivers/iommu/io-pgtable.c     |  1 +
 include/linux/io-pgtable.h     |  6 ++++
 3 files changed, 66 insertions(+)

diff --git a/drivers/iommu/io-pgtable-arm.c b/drivers/iommu/io-pgtable-arm.c
index 87def58e79b5..2f63443fd115 100644
--- a/drivers/iommu/io-pgtable-arm.c
+++ b/drivers/iommu/io-pgtable-arm.c

@@ -127,6 +127,9 @@
 #define ARM_MALI_LPAE_MEMATTR_IMP_DEF	0x88ULL
 #define ARM_MALI_LPAE_MEMATTR_WRITE_ALLOC 0x8DULL
 
+#define APPLE_DART_PTE_PROT_NO_WRITE (1<<7)
+#define APPLE_DART_PTE_PROT_NO_READ (1<<8)
+
 /* IOPTE accessors */
 #define iopte_deref(pte,d) __va(iopte_to_paddr(pte, d))
 

@@ -381,6 +384,15 @@ static arm_lpae_iopte arm_lpae_prot_to_pte(struct arm_lpae_io_pgtable *data,
 {
 	arm_lpae_iopte pte;
 
+	if (data->iop.fmt == ARM_APPLE_DART) {
+		pte = 0;
+		if (!(prot & IOMMU_WRITE))
+			pte |= APPLE_DART_PTE_PROT_NO_WRITE;
+		if (!(prot & IOMMU_READ))
+			pte |= APPLE_DART_PTE_PROT_NO_READ;
+		return pte;
+	}
+
 	if (data->iop.fmt == ARM_64_LPAE_S1 ||
 	    data->iop.fmt == ARM_32_LPAE_S1) {
 		pte = ARM_LPAE_PTE_nG;

@@ -1043,6 +1055,48 @@ arm_mali_lpae_alloc_pgtable(struct io_pgtable_cfg *cfg, void *cookie)
 	return NULL;
 }
 
+static struct io_pgtable *
+apple_dart_alloc_pgtable(struct io_pgtable_cfg *cfg, void *cookie)
+{
+	struct arm_lpae_io_pgtable *data;
+
+	if (cfg->ias > 36)
+		return NULL;
+	if (cfg->oas > 36)
+		return NULL;
+
+	if (!cfg->coherent_walk)
+		return NULL;