Add Asynchronous UART implementation, which does not drop data
when automatic hardware-flow-control is set in the device tree.
With automatic hardware flow control, the CTS pin will be
automatically deactivated when there are no more asynchronous
UART RX buffers available. After buffer space becomes available,
and UART RX is restarted, the CTS pin will be activated.
Signed-off-by: Markus Lassila <markus.lassila@nordicsemi.no>
This PR adds the following modem modules to the subsys/modem
folder:
- chat: Light implementation of the Linux chat program, used to
send and receive text based commands statically created
scripts.
- cmux: Implementation of the CMUX protocol
- pipe: Thread-safe async data-in/data-out binding layer between
modem modules.
- ppp: Implementation of the PPP protocol, binding the Zephyr PPP
L2 stack with the data-in/data-out pipe.
These modules use the abstract pipes to communicate between each
other. To bind them with the hardware, the following backends
are provided:
- TTY: modem pipe <-> POSIX TTY file
- UART: modem pipe <-> UART, async and ISR APIs supported
The backends are used to abstract away the physical layer, UART,
TTY, IPC, I2C, SPI etc, to a modem modules friendly pipe.
Signed-off-by: Bjarki Arge Andreasen <baa@trackunit.com>
