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 <robh+dt@xxxxxxxxxx>
> CC: Frank Rowand <frowand.list@xxxxxxxxx>
> Signed-off-by: Robin Murphy <robin.murphy@xxxxxxx>
> ---
>
> 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?
Will
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