`tms570_sci_interrupt_handler()` is called when an RX interrupt fires. It checks
in the register `FLR`, the `RXRDY` bit (Receiver ready flag - indicate that the
SCIRD contains new data). If it is set, it calls
`tms570_sci_read_received_chars()`.
`tms570_sci_read_received_chars()` checks the register `RD` against 0. If it is
non zero, it returns 1 to indicate that one byte was read.
In the old behavior, if it is zero, the function returns 0 to indicate that no
data was read.
The new behavior is to not silently drop 0x00 bytes. Ignoring 0x00 bytes is fine
when working with printable text (which, I assume, is how this driver was
tested), but as soon as the UART is used in non canonical (raw) mode, with
potentially 0x00 bytes, these bytes will be silently dropped, causing issues in
the data/protocol layer above.
Update #4982.
Change license to BSD-2-Clause according to file history and contributor
agreements. Add Doxygen file comments.
Update #3053.
Update #3707.
Update #4982.
