USART_SR_TC
isr, (isr & USART_SR_TC),
(isr & USART_SR_TC),
if (readl_relaxed(port->membase + ofs->isr) & USART_SR_TC)
stm32_usart_clr_bits(port, ofs->isr, USART_SR_TC);
(sr & USART_SR_TC)) {