UART_MCTL_RXFIFOTHRESH_SHIFT  456 drivers/tty/serial/bcm63xx_uart.c 	val |= (port->fifosize / 2) << UART_MCTL_RXFIFOTHRESH_SHIFT;
UART_MCTL_RXFIFOTHRESH_SHIFT   52 include/linux/serial_bcm63xx.h #define UART_MCTL_RXFIFOTHRESH_MASK	(0xf << UART_MCTL_RXFIFOTHRESH_SHIFT)