drivers/uart: Use uart_platform_refclk for all UART models

Allow the platform to override the input clock for the UART by
implementing the routine uart_platform_refclk and setting the Kconfig
value UART_OVERRIDE_REFCLK.  Provide a default uart_platform_refclk
routine which is disabled when UART_OVERRIDE_REFCLK is selected.  This
works around ROMCC not supporting weak routines.

Testing on Galileo:
*  Edit the src/mainboard/intel/galileo/ file:
   *  Add "select ADD_FSP_PDAT_FILE"
   *  Add "select ADD_FSP_RAW_BIN"
   *  Add "select ADD_RMU_FILE"
*  Place the FSP.bin file in the location specified by CONFIG_FSP_FILE
*  Place the pdat.bin files in the location specified by
*  Place the rmu.bin file in the location specified by CONFIG_RMU_FILE
*  Build EDK2 CorebootPayloadPkg/CorebootPayloadPkgIa32.dsc to generate
*  Testing is successful when CorebootPayloadPkg is able to properly
   initialize the serial port without using built-in values.

Change-Id: If4afc45a828e5ba935fecb6d95b239625e912d14
Signed-off-by: Lee Leahy <>
Tested-by: build bot (Jenkins)
Reviewed-by: Martin Roth <>
17 files changed