[PATCH v6 0/5] iommu: Support mappings/reservations in reserved-memory regions

[Thierry Reding <thierry.reding@gmail.com>]

From: Thierry Reding <treding@nvidia.com>

Hi,

This version has several fixes over the previous v5, which can be found
here:

  https://lore.kernel.org/all/20220512190052.1152377-1-thierry.reding@gmail.com/

An example is included in the DT bindings, but here is an extract of
what I've used to test this:

        reserved-memory {
                #address-cells = <2>;
                #size-cells = <2>;
                ranges;

                /*
                 * Creates an identity mapping for the framebuffer that
                 * the firmware has setup to scan out a bootsplash from.
                 */
                fb: framebuffer@92cb2000 {
                        reg = <0x0 0x92cb2000 0x0 0x00800000>;
                        iommu-addresses = <&dc0 0x0 0x92cb2000 0x0 0x00800000>;
                };

                /*
                 * Creates a reservation in the IOVA space to prevent
                 * any buffers from being mapped to that region. Note
                 * that on Tegra the range is actually quite different
                 * from this, but it would conflict with the display
                 * driver that I tested this against, so this is just
                 * a dummy region for testing.
                 */
                adsp: reservation-adsp {
                        iommu-addresses = <&dc0 0x0 0x90000000 0x0 0x00010000>;
                };
        };

        host1x@50000000 {
                dc@54200000 {
                        memory-region = <&fb>, <&adsp>;
                };
        };

This is abbreviated a little to focus on the essentials. Note also that
the ADSP reservation is not actually used on this device and the driver
for this doesn't exist yet, but I wanted to include this variant for
testing, because we'll want to use these bindings for the reservation
use-case as well at some point.

Adding Alyssa and Janne who have in the past tried to make these
bindings work on Apple M1. Also adding Sameer from the Tegra audio team
to look at the ADSP reservation and double-check that this is suitable
for our needs.

Thierry

Navneet Kumar (1):
  iommu/tegra-smmu: Support managed domains

Thierry Reding (4):
  dt-bindings: reserved-memory: Document iommu-addresses
  iommu: Implement of_iommu_get_resv_regions()
  iommu: dma: Use of_iommu_get_resv_regions()
  iommu/tegra-smmu: Add support for reserved regions

 .../reserved-memory/reserved-memory.txt       |  1 -
 .../reserved-memory/reserved-memory.yaml      | 62 +++++++++++++
 drivers/iommu/dma-iommu.c                     |  3 +
 drivers/iommu/of_iommu.c                      | 88 +++++++++++++++++++
 drivers/iommu/tegra-smmu.c                    | 82 +++++++++++++----
 include/linux/of_iommu.h                      |  8 ++
 6 files changed, 225 insertions(+), 19 deletions(-)
 delete mode 100644 Documentation/devicetree/bindings/reserved-memory/reserved-memory.txt

-- 
2.36.1