Even though radio driver can report in its capabilities that it does
support CSMA CA, there's no way in the driver to select how the frame
should be transmitted (with CSMA or without). As layers above radio
driver (Thread, Zigbee) can expect that both TX modes are available, we
need to extend the API to allow either of these modes.
This commits extends the API `tx` function with an extra parameter,
`ieee802154_tx_mode`, which informs the driver how the packet should be
transmitted. Currently, the following modes are specified:
* direct (regular tx, no cca, just how it worked so far),
* CCA before transmission,
* CSMA CA before transmission,
* delayed TX,
* delayed TX with CCA
Assume that radios that reported CSMA CA capability transmit in CSMA CA
mode by default, all others will support direct mode.
Signed-off-by: Robert Lubos <robert.lubos@nordicsemi.no>
1fb418df4c