Cut and paste this URL to share the unmodified register and value:
https://regviz.com/r/Atmel/AT91SAM9G25/USART1/CSR_SPI_MODE#0x0
Channel Status Register
Receiver Ready
Transmitter Ready
Overrun Error
Transmitter Empty
Underrun Error
https://github.com/cmsis-svd/cmsis-svd-data