[PATCH v2 5/5] iommu/arm-smmu: Setup identity domain for boot mappings

[Will Deacon]

On Thu, Jul 16, 2020 at 05:16:19PM -0700, Bjorn Andersson wrote:
> With many Qualcomm platforms not having functional S2CR BYPASS a
> temporary IOMMU domain, without translation, needs to be allocated in
> order to allow these memory transactions.
> 
> Unfortunately the boot loader uses the first few context banks, so
> rather than overwriting a active bank the last context bank is used and
> streams are diverted here during initialization.
> 
> This also performs the readback of SMR registers for the Qualcomm
> platform, to trigger the mechanism.
> 
> This is based on prior work by Thierry Reding and Laurentiu Tudor.
> 
> Tested-by: John Stultz <john.stultz at linaro.org>
> Tested-by: Vinod Koul <vkoul at kernel.org>
> Signed-off-by: Bjorn Andersson <bjorn.andersson at linaro.org>
> ---
> 
> Changes since v1:
> - Rebased to avoid conflict
> - Picked up tested-by
> 
>  drivers/iommu/arm-smmu-qcom.c | 11 +++++
>  drivers/iommu/arm-smmu.c      | 79 +++++++++++++++++++++++++++++++++--

Perhaps the CB allocator callback can help to reduce the changes to the core
driver here. What do you think?

Will