iommu: Introduce iommu_fwspec

Introduce a common structure to hold the per-device firmware data that
most IOMMU drivers need to keep track of. This enables us to configure
much of that data from common firmware code, and consolidate a lot of
the equivalent implementations, device look-up tables, etc. which are
currently strewn across IOMMU drivers.

This will also be enable us to address the outstanding "multiple IOMMUs
on the platform bus" problem by tweaking IOMMU API calls to prefer
dev->fwspec->ops before falling back to dev->bus->iommu_ops, and thus
gracefully handle those troublesome systems which we currently cannot.

As the first user, hook up the OF IOMMU configuration mechanism. The
driver-defined nature of DT cells means that we still need the drivers
to translate and add the IDs themselves, but future users such as the
much less free-form ACPI IORT will be much simpler and self-contained.

CC: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Suggested-by: Will Deacon <will.deacon@arm.com>
Signed-off-by: Robin Murphy <robin.murphy@arm.com>
Signed-off-by: Will Deacon <will.deacon@arm.com>

1 files changed, 3 insertions, 0 deletions

diff --git a/include/linux/device.h b/include/linux/device.h
index 38f02814d53a..bc41e87a969b 100644
--- a/include/linux/device.h
+++ b/include/linux/device.h
@@ -41,6 +41,7 @@ struct device_node;
 struct fwnode_handle;
 struct iommu_ops;
 struct iommu_group;
+struct iommu_fwspec;
 
 struct bus_attribute {
         struct attribute        attr;
@@ -765,6 +766,7 @@ struct device_dma_parameters {
  *              gone away. This should be set by the allocator of the
  *              device (i.e. the bus driver that discovered the device).
  * @iommu_group: IOMMU group the device belongs to.
+ * @iommu_fwspec: IOMMU-specific properties supplied by firmware.
  *
  * @offline_disabled: If set, the device is permanently online.
  * @offline:    Set after successful invocation of bus type's .offline().
@@ -849,6 +851,7 @@ struct device {
 
         void    (*release)(struct device *dev);
         struct iommu_group      *iommu_group;
+        struct iommu_fwspec     *iommu_fwspec;
 
         bool                    offline_disabled:1;
         bool                    offline:1;