[PATCH v2] iommu/ipmmu-vmsa: Do not replace bus IOMMU ops on driver init.

From: Liviu Dudau
Date: Wed Sep 20 2017 - 10:14:07 EST

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@xxxxxxx>
Cc: Laurent Pinchart <laurent.pinchart+renesas@xxxxxxxxxxxxxxxx>
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 195d6e93ac718..31912997bffdf 100644
--- a/drivers/iommu/ipmmu-vmsa.c
+++ b/drivers/iommu/ipmmu-vmsa.c
@@ -966,10 +966,11 @@ static int ipmmu_probe(struct platform_device *pdev)
return ret;

- * 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);

platform_set_drvdata(pdev, mmu);

@@ -1006,27 +1007,7 @@ 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);

MODULE_AUTHOR("Laurent Pinchart <laurent.pinchart@xxxxxxxxxxxxxxxx>");