According to L4/L0/G0 RM, in case of clock error, interrupt flag must
be cleared, and CECS flag should be cleared as soon as clock meets
requirement.
Reviewed-on: https://github.com/libopencm3/libopencm3/pull/1062
If noise source error occurs, flag must be cleared and data register
must be discarded (at least 12 reads to flush pipeline on G0). Other
device mention start/restart of chip, so, do both (better safe than
sorry).
Reviewed-on: https://github.com/libopencm3/libopencm3/pull/1062
Simplified blocking API, with an async routine if you really need it.
Follows as best as I can understand the reference manual, but testing
those conditions will be difficult.
