tree d04564c12a9c4148560013dbd8ba0a799480ee1f
parent f01cc778bd652174f76b437cc8c1be1f3fdac10a
author Andre Przywara <andre.przywara@arm.com> 1615822429 +0000
committer Will Deacon <will@kernel.org> 1616060685 +0000

hw/serial: ARM/arm64: Use MMIO at higher addresses

Using the UART devices at their legacy I/O addresses as set by IBM in
1981 was a kludge we used for simplicity on ARM platforms as well.
However this imposes problems due to their missing alignment and overlap
with the PCI I/O address space.

Now that we can switch a device easily between using ioports and MMIO,
let's move the UARTs out of the first 4K of memory on ARM platforms.

That should be transparent for well behaved guests, since the change is
naturally reflected in the device tree. Even "earlycon" keeps working,
as the stdout-path property is adjusted automatically.

People providing direct earlycon parameters via the command line need to
adjust it to: "earlycon=uart,mmio,0x1000000".

Signed-off-by: Andre Przywara <andre.przywara@arm.com>
Reviewed-by: Alexandru Elisei <alexandru.elisei@arm.com>
Link: https://lore.kernel.org/r/20210315153350.19988-22-andre.przywara@arm.com
Signed-off-by: Will Deacon <will@kernel.org>