'ARM Server Base Boot Requiremets' [1] mentions SPCR (Serial Port
Console Redirection Table) [2] as a mandatory ACPI table that
specifies the configuration of serial console.
Defer initialization of DT earlycon until ACPI/DT decision is made.
Parse the ACPI SPCR table, setup earlycon if required,
enable specified console.
Thanks to Peter Hurley for explaining how this should work.
Signed-off-by: Aleksey Makarov <aleksey.makarov@linaro.org> Acked-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com> Reviewed-by: Peter Hurley <peter@hurleysoftware.com> Tested-by: Kefeng Wang <wangkefeng.wang@huawei.com> Tested-by: Christopher Covington <cov@codeaurora.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>