Split out CDC ACM parts of "gadget serial" to a "function driver".
Some key structural differences from the previous ACM support, shared
with with the generic serial function (next patch):
- As a function driver, it can be combined with other functions.
One gadget configuration could offer both serial and network
links, as an example.
- One serial port can be exposed in multiple configurations;
the /dev/ttyGS0 node could be exposed regardless of which
config the host selected.
- One configuration can expose multiple serial ports, such as
ttyGS0, ttyGS1, ttyGS2, and ttyGS3.
This code should be a lot easier to understand than the previous
all-in-one-big-file version of the driver.
Signed-off-by: David Brownell <dbrownell@users.sourceforge.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
