[drivers] UART

[arunthomas]

Description

Implement Tock driver for gpio

Tasks

• [x] Audit the driver for missing functionality
• [x] Implement any missing driver functionality
• [x] Implement missing HIL functionality (if needed)
• [ ] Implement tests

[jon-flatley]

Task List:

• [x] RecieveAdvanced implementation
• [ ] Create a HIL for alert_test.
• [x] Ensure Transmit::transmit_abort, Transmit::transmit_word, Receive::receive_abort, and Receive::receive_word always fail as they do for all other Tock boards. Investigate if an implementation for these functions is needed.
• [ ] Implement interrupts:
  • [ ] TX_WATERMARK - Logic or notification relating to the watermark.
  • [x] RX_OVERFLOW
  • [x] RX_FRAME_ERR
  • [x] RX_BREAK_ERR - UART has disconnected, send error to client. Support error in HIL?
  • [x] RX_TIMEOUT - Send error to client. Support error in HIL?
  • [x] RX_PARITY_ERR
• [ ] Interrupt test
• [ ] Config parameters and validation. Fields that need to be added to UartParams:
  • [x] Baud rate
  • [x] Parity
  • [ ] Stop bit
  • [ ] Width check

[rnongie]

Note - This task has been simplified to focus on implementing driver functionality. The "implement driver tests" has been moved to #39

Please feel free to close this task when driver functionality is complete.