Adds a communications backend based on the asynchronous UART API,
instead of the interrupt-driven UART API. The primary advantage of this
backend is an improved robustness to dropping bytes under high interrupt
or critical section loads.
Under all loads system efficiency is improved by:
* Reducing the time spent writing out individual bytes.
* Reducing the number of UART interrupts fired.
* Waking up the RX thread much less often.
When utilising this backend over `nordic,nrf-uarte` on a nRF52840, the
baudrate of an esp-at modem could be pushed to at least 921600 without
dropping bytes, compared to a maximum of 230400 with the interrupt API.
Signed-off-by: Jordan Yates <jordan.yates@data61.csiro.au>
In order to bring consistency in-tree, migrate all drivers to the new
prefix <zephyr/...>. Note that the conversion has been scripted, refer
to #45388 for more details.
Signed-off-by: Gerard Marull-Paretas <gerard.marull@nordicsemi.no>
So far modem API used UART device names / labels. Change API to operate
on device pointers instead, so that we stop using device_get_binding()
in modem core and in some DT compatible modem drivers.
Signed-off-by: Marcin Niestroj <m.niestroj@emb.dev>
So far all received bytes over UART where blindly drained and pushed to
ring_buf. This approach is okay for UART devices without configured HW
flow control, as it basically decouples data processing from ISR handler
and gives more time before data overrun. However when HW flow control
is enabled, such behavior somehow suppresses UART flow control
advantage, because data can overrun when pushing to ring_buf.
Allow drivers utilizing modem_context framework to pass information
about whether HW flow control is enabled or not. If it is enabled, then
read data from UART FIFO to the point when RX ring_buf is totally filled
and follow such situation by disabling RX interrupt. Incoming data will
be paused on HW level, so there is lots of time for RX thread to process
ring_buf content. Reenable RX interrupts after all data in ring_buf is
processed, so that number of context switches is kept at minimum level.
Signed-off-by: Marcin Niestroj <m.niestroj@grinn-global.com>
This API allows to drop use of preallocated isr_buf. Most importantly as
a result RAM usage is reduced for each driver utilizing modem_context
framework. Additionally there is less copying done in ISR context, as
data is direcly read from UART FIFO to ring_buf.
Signed-off-by: Marcin Niestroj <m.niestroj@grinn-global.com>
This is needed if muxing is enabled in which case we must
change the UART to muxing UART after the AT+CMUX command
has succeed.
Signed-off-by: Jukka Rissanen <jukka.rissanen@linux.intel.com>
Jordan Yates