arm64: mm: change IOMMU notifier action to attach DMA ops

arm64: mm: change IOMMU notifier action to attach DMA ops

Current bus notifier in ARM64 (__iommu_attach_notifier)
attempts to attach dma_ops to a device on BUS_NOTIFY_ADD_DEVICE
action notification.

This will cause issues on ACPI based systems, where PCI devices
can be added before the IOMMUs the devices are attached to
had a chance to be probed, causing failures on attempts to
attach dma_ops in that the domain for the respective IOMMU
may not be set-up yet by the time the bus notifier is run.

Devices dma_ops do not require to be set-up till the matching
device drivers are probed. This means that instead of running
the notifier attaching dma_ops to devices (__iommu_attach_notifier)
on BUS_NOTIFY_ADD_DEVICE action, it can be run just before the
device driver is bound to the device in question (on action
BUS_NOTIFY_BIND_DRIVER) so that it is certain that its IOMMU
group and domain are set-up accordingly at the time the
notifier is triggered.

This patch changes the notifier action upon which dma_ops
are attached to devices and defer it to driver binding time,
so that IOMMU devices have a chance to be probed and to register
their bus notifiers before the dma_ops attach sequence for a
device is actually carried out.

As a result we also no longer need worry about racing with
iommu_bus_notifier(), or about retrying the queue in case devices
were added too early on DT-based systems, so clean up the notifier
itself plus the additional workaround from 722ec35f7fae ("arm64:
dma-mapping: fix handling of devices registered before arch_initcall")

Acked-by: Will Deacon <will.deacon@arm.com>
Cc: Marek Szyprowski <m.szyprowski@samsung.com>
Signed-off-by: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>
[rm: get rid of other now-redundant bits]
Signed-off-by: Robin Murphy <robin.murphy@arm.com>
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>