[PATCH 0/3] Qualcomm quirky SMMU support

[Sumit Garg]

Hi Caleb,

On Tue, 12 Dec 2023 at 00:11, Caleb Connolly <caleb.connolly at linaro.org> wrote:
>
> Qualcomm platforms are heavily locked down, in many cases offering no
> way for users to gain EL2 or EL3 code execution and including many
> additional security features. Among these are modifications made to
> the SMMU behaviour (done by having the hypervisor intercept register
> accesses). On many platforms it is not possible to disable the SMMU,
> and not possible to configure streams in BYPASS.

I suppose SDM845 is one of those.

>
> To enable support for peripherals like USB which depend on DMA, we must
> allocate a context bank on the SMMU and configure an IDENTITY mapping.
>
> This patch series fixes support for building IOMMU without CONFIG_PCI.
>
> Then, it introduces first introduces support for a .connect() op in
> IOMMU drivers, this is called before the peripheral drivers .probe()
> function and allows for IOMMU devices to perform one-time setup.
>
> Lastly, introduce a new driver which supports the SMMU as found on
> Qualcomm platforms, when a DMA capable peripherals is probed, this
> driver will first see if the previous stage bootloader configured a
> context bank for the given stream ID already, and if not then it
> allocates and configures one so that DMA accesses will work.
>
> There are no in-tree users for this driver yet, however it is required
> for upcoming USB support on SDM845 and future Qualcomm platforms.
>

Is there any other pending stuff for USB to be supported on SDM845? If
not then you should enable USB alongside this patch-set as without a
user its hard to justify this driver merge as it is.

-Sumit

> ---
> Caleb Connolly (3):
>       iommu: fix compilation when CONFIG_PCI disabled
>       iommu: add a connect op
>       iommu: add qcom-hyp-smmu
>
>  drivers/iommu/Kconfig         |  16 ++
>  drivers/iommu/Makefile        |   1 +
>  drivers/iommu/iommu-uclass.c  |  16 +-
>  drivers/iommu/qcom-hyp-smmu.c | 396 ++++++++++++++++++++++++++++++++++++++++++
>  include/iommu.h               |   9 +
>  5 files changed, 436 insertions(+), 2 deletions(-)
> ---
> base-commit: 8806443ed784dad5b5daf351b0175acb3343e729
>
> // Caleb (they/them)
>