GCC have not been capable enough to catch some linker errors which arose when
ethernet support for LWIP was disabled. Checks have been added to make sure that
unrefrenced code is not linked in.
nsapi_ppp glue layer is made more transparent to public cellular API. Storage of IP
addresses is removed. PPP layer already stores the addresses, so we pass the pointer back
to the upper layers.
If PPP is not used, we provide dummy functions.
In case of carrier lost, we would like to inform PPP data pump.
That involved setting up link status flag down semaphores.
mbed_lwip_bringup() and mbed_lwip_bringdown() had been Ethernet specific only.
We extend these routines to support PPP as well. Currently we support only one interface
at a time. However, future enhancement to multi interface support should be trivial.
mbed_ppp_init() is extended to take a function ptr.
ppp_lwip will call this callback upon a change in ppp link status.
in the beginning, the Ublox driver waits until the PPP link is established properly.
This is a glue layer between LWIP PPP implementation and a device type FileHandle
stream. This enables an external interface which has a FileHandle, utilize LWIP network
stack via PPP, e.g., Cellular device, WiFi chips etc.
Its totally transparent to external device. Only thing this layer is interested in, is a
FileHandle. Similar is true for for the external device, it just hands over its stream to this
PPP layer and rest of the magic is done by this layer.
Hasnain Virk
Kevin Bracey