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Subject[PATCH] iommu/ipmmu-vmsa: Do not replace bus IOMMU ops on driver init.
Date
If the IPMMU driver is compiled in the kernel it will replace the
platform bus IOMMU ops on running the ipmmu_init() function, regardless
if there is any IPMMU hardware present or not. This screws up systems
that just want to build a generic kernel that runs on multiple platforms
and use a different IOMMU implementation.

Move the bus_set_iommu() call at the end of the ipmmu_probe() function
when we know that hardware is present. With current IOMMU framework it
should be safe (at least for OF case).

Now that the ipmmu_init() and ipmmu_exit() functions are simple calls to
platform_driver_register() and platform_driver_unregister(), replace
them with the module_platform_driver() macro call.

Signed-off-by: Liviu Dudau <Liviu.Dudau@arm.com>
Cc: Laurent Pinchart <laurent.pinchart+renesas@ideasonboard.com>
---
drivers/iommu/ipmmu-vmsa.c | 29 +++++------------------------
1 file changed, 5 insertions(+), 24 deletions(-)

diff --git a/drivers/iommu/ipmmu-vmsa.c b/drivers/iommu/ipmmu-vmsa.c
index 2a38aa15be17d..c60569c74678d 100644
--- a/drivers/iommu/ipmmu-vmsa.c
+++ b/drivers/iommu/ipmmu-vmsa.c
@@ -1055,10 +1055,11 @@ static int ipmmu_probe(struct platform_device *pdev)
ipmmu_device_reset(mmu);

/*
- * We can't create the ARM mapping here as it requires the bus to have
- * an IOMMU, which only happens when bus_set_iommu() is called in
- * ipmmu_init() after the probe function returns.
+ * Now that we have validated the presence of the hardware, set
+ * the bus IOMMU ops to enable future domain and device setup.
*/
+ if (!iommu_present(&platform_bus_type))
+ bus_set_iommu(&platform_bus_type, &ipmmu_ops);

spin_lock(&ipmmu_devices_lock);
list_add(&mmu->list, &ipmmu_devices);
@@ -1100,27 +1101,7 @@ static struct platform_driver ipmmu_driver = {
.remove = ipmmu_remove,
};

-static int __init ipmmu_init(void)
-{
- int ret;
-
- ret = platform_driver_register(&ipmmu_driver);
- if (ret < 0)
- return ret;
-
- if (!iommu_present(&platform_bus_type))
- bus_set_iommu(&platform_bus_type, &ipmmu_ops);
-
- return 0;
-}
-
-static void __exit ipmmu_exit(void)
-{
- return platform_driver_unregister(&ipmmu_driver);
-}
-
-subsys_initcall(ipmmu_init);
-module_exit(ipmmu_exit);
+module_platform_driver(ipmmu_driver);

MODULE_DESCRIPTION("IOMMU API for Renesas VMSA-compatible IPMMU");
MODULE_AUTHOR("Laurent Pinchart <laurent.pinchart@ideasonboard.com>");
--
2.14.1
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