af0d81357c
This adds the "iommu-addresses" property to reserved-memory nodes, which
allow describing the interaction of memory regions with IOMMUs. Two use-
cases are supported:
1. Static mappings can be described by pairing the "iommu-addresses"
property with a "reg" property. This is mostly useful for adopting
firmware-allocated buffers via identity mappings. One common use-
case where this is required is if early firmware or bootloaders
have set up a bootsplash framebuffer that a display controller is
actively scanning out from during the operating system boot
process.
2. If an "iommu-addresses" property exists without a "reg" property,
the reserved-memory node describes an IOVA reservation. Such memory
regions are excluded from the IOVA space available to operating
system drivers and can be used for regions that must not be used to
map arbitrary buffers.
Each mapping or reservation is tied to a specific device via a phandle
to the device's device tree node. This allows a reserved-memory region
to be reused across multiple devices.
Reviewed-by: Rob Herring <robh@kernel.org>
Reviewed-by: Robin Murphy <robin.murphy@arm.com>
Signed-off-by: Thierry Reding <treding@nvidia.com>
Link: https://lore.kernel.org/r/20230120174251.4004100-3-thierry.reding@gmail.com
Signed-off-by: Joerg Roedel <jroedel@suse.de>
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| .. | ||
| bindings | ||
| changesets.rst | ||
| dynamic-resolution-notes.rst | ||
| index.rst | ||
| kernel-api.rst | ||
| of_unittest.rst | ||
| overlay-notes.rst | ||
| usage-model.rst | ||