net: dsa: sja1105: reorganize probe, remove, setup and teardown ordering

net: dsa: sja1105: reorganize probe, remove, setup and teardown ordering

The sja1105 driver's initialization and teardown sequence is a chaotic
mess that has gathered a lot of cruft over time. It works because there
is no strict dependency between the functions, but it could be improved.

The basic principle that teardown should be the exact reverse of setup
is obviously not held. We have initialization steps (sja1105_tas_setup,
sja1105_flower_setup) in the probe method that are torn down in the DSA
.teardown method instead of driver unbind time.

We also have code after the dsa_register_switch() call, which implicitly
means after the .setup() method has finished, which is pretty unusual.

Also, sja1105_teardown() has calls set up in a different order than the
error path of sja1105_setup(): see the reversed ordering between
sja1105_ptp_clock_unregister and sja1105_mdiobus_unregister.

Also, sja1105_static_config_load() is called towards the end of
sja1105_setup(), but sja1105_static_config_free() is also towards the
end of the error path and teardown path. The static_config_load() call
should be earlier.

Also, making and breaking the connections between struct sja1105_port
and struct dsa_port could be refactored into dedicated functions, makes
the code easier to follow.

We move some code from the DSA .setup() method into the probe method,
like the device tree parsing, and we move some code from the probe
method into the DSA .setup() method to be symmetric with its placement
in the DSA .teardown() method, which is nice because the unbind function
has a single call to dsa_unregister_switch(). Example of the latter type
of code movement are the connections between ports mentioned above, they
are now in the .setup() method.

Finally, due to fact that the kthread_init_worker() call is no longer
in sja1105_probe() - located towards the bottom of the file - but in
sja1105_setup() - located much higher - there is an inverse ordering
with the worker function declaration, sja1105_port_deferred_xmit. To
avoid that, the entire sja1105_setup() and sja1105_teardown() functions
are moved towards the bottom of the file.

Signed-off-by: Vladimir Oltean <vladimir.oltean@nxp.com>
Signed-off-by: David S. Miller <davem@davemloft.net>