[PATCH v3 3/3] iommu/tegra-smmu: Add PCI support

[Nicolin Chen]

This patch simply adds support for PCI devices.

Signed-off-by: Nicolin Chen 
---

Changelog
v2->v3
 * Replaced ternary conditional operator with if-else in .device_group()
 * Dropped change in tegra_smmu_remove()
v1->v2
 * Added error-out labels in tegra_smmu_probe()
 * Dropped pci_request_acs() since IOMMU core would call it.

 drivers/iommu/tegra-smmu.c | 35 ++-
 1 file changed, 26 insertions(+), 9 deletions(-)

diff --git a/drivers/iommu/tegra-smmu.c b/drivers/iommu/tegra-smmu.c
index 636dc3b89545..db98ca334eae 100644
--- a/drivers/iommu/tegra-smmu.c
+++ b/drivers/iommu/tegra-smmu.c
@@ -10,6 +10,7 @@
 #include 
 #include 
 #include 
+#include 
 #include 
 #include 
 #include 
@@ -882,7 +883,11 @@ static struct iommu_group *tegra_smmu_device_group(struct 
device *dev)
group->smmu = smmu;
group->soc = soc;
 
-   group->group = iommu_group_alloc();
+   if (dev_is_pci(dev))
+   group->group = pci_device_group(dev);
+   else
+   group->group = generic_device_group(dev);
+
if (IS_ERR(group->group)) {
devm_kfree(smmu->dev, group);
mutex_unlock(&smmu->lock);
@@ -1079,22 +1084,34 @@ struct tegra_smmu *tegra_smmu_probe(struct device *dev,
iommu_device_set_fwnode(&smmu->iommu, dev->fwnode);
 
err = iommu_device_register(&smmu->iommu);
-   if (err) {
-   iommu_device_sysfs_remove(&smmu->iommu);
-   return ERR_PTR(err);
-   }
+   if (err)
+   goto err_sysfs;
 
err = bus_set_iommu(&platform_bus_type, &tegra_smmu_ops);
-   if (err < 0) {
-   iommu_device_unregister(&smmu->iommu);
-   iommu_device_sysfs_remove(&smmu->iommu);
-   return ERR_PTR(err);
+   if (err < 0)
+   goto err_unregister;
+
+#ifdef CONFIG_PCI
+   if (!iommu_present(&pci_bus_type)) {
+   err = bus_set_iommu(&pci_bus_type, &tegra_smmu_ops);
+   if (err < 0)
+   goto err_bus_set;
}
+#endif
 
if (IS_ENABLED(CONFIG_DEBUG_FS))
tegra_smmu_debugfs_init(smmu);
 
return smmu;
+
+err_bus_set:
+   bus_set_iommu(&platform_bus_type, NULL);
+err_unregister:
+   iommu_device_unregister(&smmu->iommu);
+err_sysfs:
+   iommu_device_sysfs_remove(&smmu->iommu);
+
+   return ERR_PTR(err);
 }
 
 void tegra_smmu_remove(struct tegra_smmu *smmu)
-- 
2.17.1

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Re: [PATCH v3 3/3] iommu/tegra-smmu: Add PCI support

[Dmitry Osipenko]

...
> +#ifdef CONFIG_PCI
> + if (!iommu_present(&pci_bus_type)) {


In the previous reply you said that you're borrowing this check from the
arm-smmu driver, but arm-smmu also has a similar check for
platform_bus_type, while Tegra SMMU driver doesn't have it. Hence I'm
objecting the necessity of having this check.

Please give a rationale for having this check in the code. And please
note that cargo cult isn't a rationale to me.
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Re: [PATCH v3 3/3] iommu/tegra-smmu: Add PCI support

[Nicolin Chen]

On Wed, Sep 30, 2020 at 05:53:20PM +0300, Dmitry Osipenko wrote:
> ...
> > +#ifdef CONFIG_PCI
> > +   if (!iommu_present(&pci_bus_type)) {
> 
> 
> In the previous reply you said that you're borrowing this check from the
> arm-smmu driver, but arm-smmu also has a similar check for
> platform_bus_type, while Tegra SMMU driver doesn't have it. Hence I'm
> objecting the necessity of having this check.
> 
> Please give a rationale for having this check in the code. And please
> note that cargo cult isn't a rationale to me.

Okay, okayI will remove it upon testing.
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