iommu/dart: Add DART iommu driver

Apple's new SoCs use iommus for almost all peripherals. These Device
Address Resolution Tables must be setup before these peripherals can
act as DMA masters.

Tested-by: Alyssa Rosenzweig <alyssa@rosenzweig.io>
Signed-off-by: Sven Peter <sven@svenpeter.dev>
Link: https://lore.kernel.org/r/20210803121651.61594-4-sven@svenpeter.dev
Signed-off-by: Joerg Roedel <jroedel@suse.de>

MAINTAINERS

@@ -1267,6 +1267,7 @@ M:	Sven Peter <sven@svenpeter.dev>
 L:	iommu@lists.linux-foundation.org
 S:	Maintained
 F:	Documentation/devicetree/bindings/iommu/apple,dart.yaml
+F:	drivers/iommu/apple-dart.c
 
 APPLE SMC DRIVER
 M:	Henrik Rydberg <rydberg@bitmath.org>

drivers/iommu/Kconfig

@@ -290,6 +290,20 @@ config SPAPR_TCE_IOMMU
 	  Enables bits of IOMMU API required by VFIO. The iommu_ops
 	  is not implemented as it is not necessary for VFIO.
 
+config APPLE_DART
+	tristate "Apple DART IOMMU Support"
+	depends on ARM64 || (COMPILE_TEST && !GENERIC_ATOMIC64)
+	select IOMMU_API
+	select IOMMU_IO_PGTABLE_LPAE
+	default ARCH_APPLE
+	help
+	  Support for Apple DART (Device Address Resolution Table) IOMMUs
+	  found in Apple ARM SoCs like the M1.
+	  This IOMMU is required for most peripherals using DMA to access
+	  the main memory.
+
+	  Say Y here if you are using an Apple SoC.
+
 # ARM IOMMU support
 config ARM_SMMU
 	tristate "ARM Ltd. System MMU (SMMU) Support"

drivers/iommu/Makefile

@@ -29,3 +29,4 @@ obj-$(CONFIG_HYPERV_IOMMU) += hyperv-iommu.o
 obj-$(CONFIG_VIRTIO_IOMMU) += virtio-iommu.o
 obj-$(CONFIG_IOMMU_SVA_LIB) += iommu-sva-lib.o io-pgfault.o
 obj-$(CONFIG_SPRD_IOMMU) += sprd-iommu.o
+obj-$(CONFIG_APPLE_DART) += apple-dart.o