On 14/06/16 15:45, Will Deacon wrote:
On Fri, Jun 03, 2016 at 06:15:39PM +0100, Robin Murphy wrote:
Now that we have a way to pick up the RID translation and target IOMMU,
hook up of_iommu_configure() to bring PCI devices into the of_xlate
mechanism and allow them IOMMU-backed DMA ops without the need for
driver-specific handling.
CC: Rob Herring <[email protected]>
CC: Frank Rowand <[email protected]>
Signed-off-by: Robin Murphy <[email protected]>
---
v2: Skip disabled IOMMUs.
drivers/iommu/of_iommu.c | 44 +++++++++++++++++++++++++++++++++++++-------
1 file changed, 37 insertions(+), 7 deletions(-)
diff --git a/drivers/iommu/of_iommu.c b/drivers/iommu/of_iommu.c
index 662f9a600f4f..5716131199b3 100644
--- a/drivers/iommu/of_iommu.c
+++ b/drivers/iommu/of_iommu.c
@@ -22,6 +22,7 @@
#include <linux/limits.h>
#include <linux/of.h>
#include <linux/of_iommu.h>
+#include <linux/of_pci.h>
#include <linux/slab.h>
static const struct of_device_id __iommu_of_table_sentinel
@@ -134,20 +135,49 @@ const struct iommu_ops *of_iommu_get_ops(struct
device_node *np)
return ops;
}
+static int __get_pci_rid(struct pci_dev *pdev, u16 alias, void *data)
+{
+ struct of_phandle_args *iommu_spec = data;
+
+ iommu_spec->args[0] = alias;
+ return iommu_spec->np == pdev->bus->dev.of_node;
+}
+
const struct iommu_ops *of_iommu_configure(struct device *dev,
struct device_node *master_np)
{
struct of_phandle_args iommu_spec;
- struct device_node *np;
+ struct device_node *np = NULL;
const struct iommu_ops *ops = NULL;
int idx;
- /*
- * We can't do much for PCI devices without knowing how
- * device IDs are wired up from the PCI bus to the IOMMU.
- */
- if (dev_is_pci(dev))
- return NULL;
+ if (dev_is_pci(dev)) {
+ /*
+ * Start by tracing the RID alias down the PCI topology as
+ * far as the host bridge whose OF node we have...
+ */
+ iommu_spec.np = master_np;
+ pci_for_each_dma_alias(to_pci_dev(dev), __get_pci_rid,
+ &iommu_spec);
+ /*
+ * ...then find out what that becomes once it escapes the PCI
+ * bus into the system beyond, and which IOMMU it ends up at.
+ */
+ if (of_pci_map_rid(master_np, "iommu-map", iommu_spec.args[0],
+ &np, iommu_spec.args) ||
+ !of_device_is_available(np))
+ return NULL;
Hmm, do we need to of_node_put(np) in the case that it's not available?
Ah yes, now I see; I moved the put into the loop iteration for the
non-PCI case so that a "continue" does the job, but I've not handled the
equivalent here.
Robin.
Will
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