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iommu/io-pgtable: Move Apple DART support to its own file

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The pte format used by the DARTs found in the Apple M1 (t8103) is not
fully compatible with io-pgtable-arm. The 24 MSB are used for subpage
protection (mapping only parts of page) and conflict with the address
mask. In addition bit 1 is not available for tagging entries but disables
subpage protection. Subpage protection could be useful to support a CPU
granule of 4k with the fixed IOMMU page size of 16k.

The DARTs found on Apple M1 Pro/Max/Ultra use another different pte
format which is even less compatible. To support an output address size
of 42 bit the address is shifted down by 4. Subpage protection is
mandatory and bit 1 signifies uncached mappings used by the display
controller.

It would be advantageous to share code for all known Apple DART
variants to support common features. The page table allocator for DARTs
is less complex since it uses a two levels of translation table without
support for huge pages.

Signed-off-by: Janne Grunau <j@jannau.net>
Acked-by: Robin Murphy <robin.murphy@arm.com>
Acked-by: Sven Peter <sven@svenpeter.dev>
Acked-by: Hector Martin <marcan@marcan.st>
Link: https://lore.kernel.org/r/20220916094152.87137-3-j@jannau.net
[ joro: Fix compile warning in __dart_alloc_pages()]
Signed-off-by: Joerg Roedel <jroedel@suse.de>
This commit is contained in:
Janne Grunau
2022-09-16 11:41:49 +02:00
committed by Joerg Roedel
parent 7e18e42e4b
commit 745ef1092b
6 changed files with 442 additions and 64 deletions
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13
drivers/iommu/Kconfig
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@@ -67,6 +67,17 @@ config IOMMU_IO_PGTABLE_ARMV7S_SELFTEST
If unsure, say N here.
config IOMMU_IO_PGTABLE_DART
bool "Apple DART Formats"
select IOMMU_IO_PGTABLE
depends on ARM64 || (COMPILE_TEST && !GENERIC_ATOMIC64)
help
Enable support for the Apple DART pagetable formats. These include
the t8020 and t6000/t8110 DART formats used in Apple M1/M2 family
SoCs.
If unsure, say N here.
endmenu
config IOMMU_DEBUGFS
@@ -294,7 +305,7 @@ config APPLE_DART
tristate "Apple DART IOMMU Support"
depends on ARCH_APPLE || (COMPILE_TEST && !GENERIC_ATOMIC64)
select IOMMU_API
select IOMMU_IO_PGTABLE_LPAE
select IOMMU_IO_PGTABLE_DART
default ARCH_APPLE
help
Support for Apple DART (Device Address Resolution Table) IOMMUs