This PR adds a mechanism to avoid calling open() or close()
on pipes which are already opened or closed respectively.
This optimization can help simplify backends implementing
the modem_pipe API by avoiding duplicated boilerplate code.
The TTY backend test suite has been updated to match the
new behavior.
Signed-off-by: Bjarki Arge Andreasen <bjarkix123@gmail.com>
This PR makes the modem_pipe instances track if they have
data ready to receive, and invoke the RECEIVE_READY event
every time they are attached if the backend implementing
the pipe has notified that receive is ready.
This mechanism ensures that modules attaching to a pipe
get the async RECEIVE_READY event immediately after
attaching to a pipe if there is data ready, instead of
having to poll the pipe, or worse, wait until newer data
becomes available.
The addition revealed a timing issue in the cmux test
suite. Specifically the CMUX instance now immediately
receives the response to a command which the CMUX
instance has not sent yet, causing it to drop the
response.
The CMUX test suite now uses the transaction
mechanism of the mock_pipe to wait for the command
before sending the response.
Signed-off-by: Bjarki Arge Andreasen <bjarkix123@gmail.com>
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>
