The mvebu PCI host controller driver uses an emulated PCI-to-PCI bridge to
leverage the core PCI kernel enumeration logic to dynamically create and
remove the MBus windows needed to access the memory and I/O regions of each
PCI interface.

In the context of this PCI-to-PCI bridge emulation, the driver emulates
all reads and writes to the PCI bridge registers.  Upon a write to the
registers configuring the I/O base and limit, the driver was creating the
MBus window and calling pci_ioremap_io() to setup the mapping.

However, it turns out that accesses to these registers are made in an IRQ
disabled context, while pci_ioremap_io() is a potentially sleeping
function.  Not only this is wrong, but it is causing fairly loud warnings
at boot time when the appropriate kernel hacking options are enabled.

This patch solves this by moving the pci_ioremap_io() call to the startup
of the driver.  At this point, we don't know how many PCI interfaces will
be enabled, so we are simply remapping the entire PCI I/O space to virtual
addresses.  This is reasonable since this I/O space is limited to 1 MB in
size, and also because the MBus windows continue to be created in a dynamic
fashion only when devices need them.
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>