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>

2 files changed, 64 insertions, 2 deletions

diff --git a/drivers/iommu/iommu.c b/drivers/iommu/iommu.c
index b06d93594436..9a2f1960873b 100644
--- a/drivers/iommu/iommu.c
+++ b/drivers/iommu/iommu.c
@@ -31,6 +31,7 @@
 #include <linux/err.h>
 #include <linux/pci.h>
 #include <linux/bitops.h>
+#include <linux/property.h>
 #include <trace/events/iommu.h>
 
 static struct kset *iommu_group_kset;
@@ -1613,3 +1614,60 @@ out:
 
 	return ret;
 }
+
+int iommu_fwspec_init(struct device *dev, struct fwnode_handle *iommu_fwnode,
+		      const struct iommu_ops *ops)
+{
+	struct iommu_fwspec *fwspec = dev->iommu_fwspec;
+
+	if (fwspec)
+		return ops == fwspec->ops ? 0 : -EINVAL;
+
+	fwspec = kzalloc(sizeof(*fwspec), GFP_KERNEL);
+	if (!fwspec)
+		return -ENOMEM;
+
+	of_node_get(to_of_node(iommu_fwnode));
+	fwspec->iommu_fwnode = iommu_fwnode;
+	fwspec->ops = ops;
+	dev->iommu_fwspec = fwspec;
+	return 0;
+}
+EXPORT_SYMBOL_GPL(iommu_fwspec_init);
+
+void iommu_fwspec_free(struct device *dev)
+{
+	struct iommu_fwspec *fwspec = dev->iommu_fwspec;
+
+	if (fwspec) {
+		fwnode_handle_put(fwspec->iommu_fwnode);
+		kfree(fwspec);
+		dev->iommu_fwspec = NULL;
+	}
+}
+EXPORT_SYMBOL_GPL(iommu_fwspec_free);
+
+int iommu_fwspec_add_ids(struct device *dev, u32 *ids, int num_ids)
+{
+	struct iommu_fwspec *fwspec = dev->iommu_fwspec;
+	size_t size;
+	int i;
+
+	if (!fwspec)
+		return -EINVAL;
+
+	size = offsetof(struct iommu_fwspec, ids[fwspec->num_ids + num_ids]);
+	if (size > sizeof(*fwspec)) {
+		fwspec = krealloc(dev->iommu_fwspec, size, GFP_KERNEL);
+		if (!fwspec)
+			return -ENOMEM;
+	}
+
+	for (i = 0; i < num_ids; i++)
+		fwspec->ids[fwspec->num_ids + i] = ids[i];
+
+	fwspec->num_ids += num_ids;
+	dev->iommu_fwspec = fwspec;
+	return 0;
+}
+EXPORT_SYMBOL_GPL(iommu_fwspec_add_ids);
diff --git a/drivers/iommu/of_iommu.c b/drivers/iommu/of_iommu.c
index 19e1e8f2f871..5b82862f571f 100644
--- a/drivers/iommu/of_iommu.c
+++ b/drivers/iommu/of_iommu.c
@@ -167,7 +167,9 @@ static const struct iommu_ops
 		return NULL;
 
 	ops = of_iommu_get_ops(iommu_spec.np);
-	if (!ops || !ops->of_xlate || ops->of_xlate(&pdev->dev, &iommu_spec))
+	if (!ops || !ops->of_xlate ||
+	    iommu_fwspec_init(&pdev->dev, &iommu_spec.np->fwnode, ops) ||
+	    ops->of_xlate(&pdev->dev, &iommu_spec))
 		ops = NULL;
 
 	of_node_put(iommu_spec.np);
@@ -196,7 +198,9 @@ const struct iommu_ops *of_iommu_configure(struct device *dev,
 		np = iommu_spec.np;
 		ops = of_iommu_get_ops(np);
 
-		if (!ops || !ops->of_xlate || ops->of_xlate(dev, &iommu_spec))
+		if (!ops || !ops->of_xlate ||
+		    iommu_fwspec_init(dev, &np->fwnode, ops) ||
+		    ops->of_xlate(dev, &iommu_spec))
 			goto err_put_node;
 
 		of_node_put(np);