linux-imx

serial: 8250_pci: Implement MSI(-X) support

There may be setups, where legacy interrupts are not available. This is
the caese, e.g., when Linux runs as guest (aka. non-root cell) of the
partitioning hypervisor Jailhouse. There, only MSI(-X) interrupts are
available for guests.

But the 8250_pci driver currently only supports legacy ints. So let's
enable MSI(-X) interrupts.

Nevertheless, this needs to handled with care: while many 8250 devices
actually claim to support MSI(-X) interrupts it should not be enabled be
default. I had at least one device in my hands with broken MSI
implementation.

So better introduce a whitelist with devices that are known to support
MSI(-X) interrupts. I tested all devices mentioned in the patch.

Signed-off-by: Ralf Ramsauer <ralf.ramsauer@oth-regensburg.de>
Link: https://lore.kernel.org/r/20190812112152.693622-1-ralf.ramsauer@oth-regensburg.de
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>