Hej,
I've taken over this series to add support for DART on M1 Pro/Max from
Sven.
Since v1 we have discovered further differences in the PTE format. It
has four differences which makes it incompatible with the one in the
M1:
- the physical addresses are shifted left by 4 bits and and have 2 more
bits inside the PTE entries
- the read/write protection flags are at a different position
- the subpage protection feature is now mandatory. For Linux we can
just configure it to always allow access to the entire page.
- BIT(1) tags "uncached" mappings (used for the display controller)
The last difference is the most troublesome since it makes the PTE format
incomaptible with iopte_type(). Handling this inside io-pgtable-arm.c
seems manageable since DART supports just a single block size. It opens
the question at which point we decide that DART uses its own
io_pgtable_ops.
There is second type of DART (t8110) present on M1 Pro/Max SoCs which
uses the same PTE format as t6000.
Janne
Sven Peter (4):
dt-bindings: iommu: dart: add t6000 compatible
iommu/io-pgtable: Add DART subpage protection support
iommu/io-pgtable: Add DART PTE support for t6000
iommu: dart: Support t6000 variant
.../devicetree/bindings/iommu/apple,dart.yaml | 4 +-
drivers/iommu/apple-dart.c | 24 +++++-
drivers/iommu/io-pgtable-arm.c | 76 ++++++++++++++++++-
drivers/iommu/io-pgtable.c | 1 +
include/linux/io-pgtable.h | 3 +
5 files changed, 101 insertions(+), 7 deletions(-)
base-commit: 3123109284176b1532874591f7c81f3837bbdc17
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2.35.1
