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Commit d7b05582 authored by Robin Murphy's avatar Robin Murphy Committed by Joerg Roedel
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iommu/of: Prepare for deferred IOMMU configuration 



IOMMU configuration represents unchanging properties of the hardware,
and as such should only need happen once in a device's lifetime, but
the necessary interaction with the IOMMU device and driver complicates
exactly when that point should be.

Since the only reasonable tool available for handling the inter-device
dependency is probe deferral, we need to prepare of_iommu_configure()
to run later than it is currently called (i.e. at driver probe rather
than device creation), to handle being retried, and to tell whether a
not-yet present IOMMU should be waited for or skipped (by virtue of
having declared a built-in driver or not).

Tested-by: default avatarMarek Szyprowski <m.szyprowski@samsung.com>
Signed-off-by: default avatarRobin Murphy <robin.murphy@arm.com>
Signed-off-by: default avatarJoerg Roedel <jroedel@suse.de>
parent 2a0c5754

drivers/iommu/of_iommu.c

+42 −1
Original line number Diff line number Diff line
@@ -96,6 +96,19 @@ int of_get_dma_window(struct device_node *dn, const char *prefix, int index, 
}

EXPORT_SYMBOL_GPL(of_get_dma_window);



static bool of_iommu_driver_present(struct device_node *np)

{

	/*

	 * If the IOMMU still isn't ready by the time we reach init, assume

	 * it never will be. We don't want to defer indefinitely, nor attempt

	 * to dereference __iommu_of_table after it's been freed.

	 */

	if (system_state > SYSTEM_BOOTING)

		return false;



	return of_match_node(&__iommu_of_table, np);

}



static const struct iommu_ops

*of_iommu_xlate(struct device *dev, struct of_phandle_args *iommu_spec)

{
@@ -104,12 +117,20 @@ static const struct iommu_ops 
	int err;



	ops = iommu_ops_from_fwnode(fwnode);

	if (!ops || !ops->of_xlate)

	if ((ops && !ops->of_xlate) ||

	    (!ops && !of_iommu_driver_present(iommu_spec->np)))

		return NULL;



	err = iommu_fwspec_init(dev, &iommu_spec->np->fwnode, ops);

	if (err)

		return ERR_PTR(err);

	/*

	 * The otherwise-empty fwspec handily serves to indicate the specific

	 * IOMMU device we're waiting for, which will be useful if we ever get

	 * a proper probe-ordering dependency mechanism in future.

	 */

	if (!ops)

		return ERR_PTR(-EPROBE_DEFER);



	err = ops->of_xlate(dev, iommu_spec);

	if (err)
@@ -186,14 +207,34 @@ const struct iommu_ops *of_iommu_configure(struct device *dev, 
					   struct device_node *master_np)

{

	const struct iommu_ops *ops;

	struct iommu_fwspec *fwspec = dev->iommu_fwspec;



	if (!master_np)

		return NULL;



	if (fwspec) {

		if (fwspec->ops)

			return fwspec->ops;



		/* In the deferred case, start again from scratch */

		iommu_fwspec_free(dev);

	}



	if (dev_is_pci(dev))

		ops = of_pci_iommu_init(to_pci_dev(dev), master_np);

	else

		ops = of_platform_iommu_init(dev, master_np);

	/*

	 * If we have reason to believe the IOMMU driver missed the initial

	 * add_device callback for dev, replay it to get things in order.

	 */

	if (!IS_ERR_OR_NULL(ops) && ops->add_device &&

	    dev->bus && !dev->iommu_group) {

		int err = ops->add_device(dev);



		if (err)

			ops = ERR_PTR(err);

	}



	return IS_ERR(ops) ? NULL : ops;

}