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author | 2017-04-10 16:50:57 +0530 | |
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committer | 2017-04-20 16:31:06 +0200 | |
commit | d7b0558230e444f29488fcee0b0b561015d16f8a (patch) | |
tree | cbe9076d119c98aa9f0562c2d2f5dbb57141e16a /drivers/iommu | |
parent | iommu/of: Refactor of_iommu_configure() for error handling (diff) | |
download | linux-d7b0558230e444f29488fcee0b0b561015d16f8a.tar.gz linux-d7b0558230e444f29488fcee0b0b561015d16f8a.tar.bz2 linux-d7b0558230e444f29488fcee0b0b561015d16f8a.zip |
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: Marek Szyprowski <m.szyprowski@samsung.com>
Signed-off-by: Robin Murphy <robin.murphy@arm.com>
Signed-off-by: Joerg Roedel <jroedel@suse.de>
Diffstat (limited to 'drivers/iommu')
-rw-r--r-- | drivers/iommu/of_iommu.c | 43 |
1 files changed, 42 insertions, 1 deletions
diff --git a/drivers/iommu/of_iommu.c b/drivers/iommu/of_iommu.c index 8f4e59985f6e..c8be889f5206 100644 --- a/drivers/iommu/of_iommu.c +++ b/drivers/iommu/of_iommu.c @@ -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; } |