xen/serial: setup UART idle mode for OMAP
The UART is not able to receive bytes when idle mode is not configured
properly, therefore setup the UART with autoidle and wakeup enabled.
Older Linux kernels (for example 3.8) configure hwmods for all devices
even if the device tree nodes for those devices is absent in device
tree, thus UART idle mode is configured too. With such kernels we can
workaround the issue by adding a fake node in the UART containing this
MMIO range, which is therefore mapped by Xen to dom0, which
reconfigures the UART, causing things to work normally.
Newer Linux Kernels (3.12 and beyond) do not configure idle mode for
UART and so this hack no longer works.
Signed-off-by: Oleksandr Dmytryshyn <oleksandr.dmytryshyn@globallogic.com>
Acked-by: Ian Campbell <ian.campbell@citrix.com>
[ ijc -- updated commit message as discussed ]
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