SMMU circular queues have a wrap bit which is used in order to
distinguish between an empty queue and a full queue.
According to SMMUv3 spec:
Each index has a wrap flag, represented by the next higher bit adjacent
to the index value contained in PROD and CONS. This bit must toggle each
time the index wraps off the high end and back onto the low end of the
buffer. It is the responsibility of the owner of each index, producer or
consumer, to toggle this bit when the owner updates the index after
wrapping. It is intended that software reads the register, increments or
wraps the index (toggling wrap when required) and writes back both wrap
and index fields at the same time.
Change-Id: Idfeb397141f3627c2878caaeaa2625fadf671d2a
Signed-off-by: Giacomo Travaglini <giacomo.travaglini@arm.com>
Reviewed-by: Michiel Van Tol <michiel.vantol@arm.com>
Reviewed-by: Adrian Herrera <adrian.herrera@arm.com>
Reviewed-on: https://gem5-review.googlesource.com/c/public/gem5/+/19311
Tested-by: kokoro <noreply+kokoro@google.com>
Reviewed-by: Ciro Santilli <ciro.santilli@arm.com>
Maintainer: Andreas Sandberg <andreas.sandberg@arm.com>
This is an implementation of the SMMUv3 architecture.
What can it do?
- Single-stage and nested translation with 4k or 64k granule. 16k would
be straightforward to add.
- Large pages are supported.
- Works with any gem5 device as long as it is issuing packets with a
valid (Sub)StreamId
What it can't do?
- Fragment stage 1 page when the underlying stage 2 page is smaller. S1
page size > S2 page size is not supported
- Invalidations take zero time. This wouldn't be hard to fix.
- Checkpointing is not supported
- Stall/resume for faulting transactions is not supported
Additional contributors:
- Michiel W. van Tol <Michiel.VanTol@arm.com>
- Giacomo Travaglini <giacomo.travaglini@arm.com>
Change-Id: Ibc606fccd9199b2c1ba739c6335c846ffaa4d564
Signed-off-by: Giacomo Travaglini <giacomo.travaglini@arm.com>
Reviewed-by: Andreas Sandberg <andreas.sandberg@arm.com>
Reviewed-on: https://gem5-review.googlesource.com/c/public/gem5/+/19008
Maintainer: Andreas Sandberg <andreas.sandberg@arm.com>
Tested-by: kokoro <noreply+kokoro@google.com>
