This patch adds the support for to create a direct iommu "bypass"
window on IODA2 bridges (such as Power8) allowing to bypass iommu
page translation completely for 64-bit DMA capable devices, thus
significantly improving DMA performances.

Additionally, this adds a hook to the struct iommu_table so that
the IOMMU API / VFIO can disable the bypass when external ownership
is requested, since in that case, the device will be used by an
environment such as userspace or a KVM guest which must not be
allowed to bypass translations.
Signed-off-by: NBenjamin Herrenschmidt <benh@kernel.crashing.org>

This uses the hooks provided by CONFIG_PPC_INDIRECT_PIO to
implement a set of hooks for IO port access to use the LPC
bus via OPAL calls for the first 64K of IO space
Signed-off-by: NBenjamin Herrenschmidt <benh@kernel.crashing.org>

We add a machine_shutdown hook that frees the OPAL interrupts
(so they get masked at the source and don't fire while kexec'ing)
and which triggers an IODA reset on all the PCIe host bridges
which will have the effect of blocking all DMAs and subsequent
PCIs interrupts.
Signed-off-by: NBenjamin Herrenschmidt <benh@kernel.crashing.org>

This adds support for PCI-X and PCIe on the p5ioc2 IO hub using
OPAL. This includes allocating & setting up TCE tables and config
space access routines.

This also supports fallbacks via RTAS when OPAL is absent, using
legacy TCE format pre-allocated via the device-tree (BML style)
Signed-off-by: NBenjamin Herrenschmidt <benh@kernel.crashing.org>

This adds a skeletton for the new Power "Non Virtualized"
platform which will be used by machines supporting running
without an hypervisor, for example in order to run KVM.

These machines will be using a new firmware called OPAL
for which the support will be provided by later patches.

The PowerNV platform is intended to be also usable under
the BML environment used internally for early CPU bringup
which is why the code also supports using RTAS instead of
OPAL in various places.
Signed-off-by: NBenjamin Herrenschmidt <benh@kernel.crashing.org>