LSR
while (!(readl(UART1_REG(LSR)) & UART_LSR_DR)) {
while (!(readl(UART1_REG(LSR)) & UART_LSR_THRE))
while (!(readl(UART1_REG(LSR)) & UART_LSR_DR)) {
while (!(readl(UART1_REG(LSR)) & UART_LSR_THRE))
while ((inb(early_serial_base + LSR) & XMTRDY) == 0 && --timeout)
while ((inb(early_serial_base + LSR) & XMTRDY) == 0 && --timeout)
while ((static_call(serial_in)(early_serial_base, LSR) & XMTRDY) == 0 && --timeout)