This patch removes gserial_setup() and gserial_cleanup() and adds
gserial_alloc_line() and gserial_free_line() to replace them.

The initial setup of u_serial happens now on module load time. A
maximum of four TTY ports can be requested which is the current limit.
In theory we could extend this limit, the hard limit is the number of
available endpoints.
alloc_tty_driver() is now called at module init time with the max
available ports. The per-line footprint here is on 32bit is 3 * size of
pointer + 60 bytes (for cdevs).
The remaining memory (struct gs_port) is allocated once a port is
requested.

With this change it is possible to load g_multi and g_serial at the same
time. GS0 receives the module that is loaded first, GS1 is received by
the next module and so on. With the configfs interface the port number
can be exported and the device node is more predictable. Nothing changes
for g_serial and friends as long as one module is used.
Signed-off-by: NSebastian Andrzej Siewior <bigeasy@linutronix.de>
Signed-off-by: NFelipe Balbi <balbi@ti.com>

Change usb_ep_enable() prototype to use endpoint
descriptor from usb_ep.

This optimization spares the FDs from saving the
endpoint chosen descriptor. This optimization is
not full though. To fully exploit this change, one
needs to update all the UDCs as well since in the
current implementation each of them saves the
endpoint descriptor in it's internal (and extended)
endpoint structure.
Signed-off-by: NTatyana Brokhman <tlinder@codeaurora.org>
Signed-off-by: NFelipe Balbi <balbi@ti.com>
Signed-off-by: NGreg Kroah-Hartman <gregkh@suse.de>

The following patch introduces a new f_obex.c function driver.
It allows userspace obex servers to use usb as transport layer
for their messages.

[ dbrownell@users.sourceforge.net: various fixes and cleanups ]
Signed-off-by: NFelipe Balbi <felipe.balbi@nokia.com>
Signed-off-by: NDavid Brownell <dbrownell@users.sourceforge.net>
Signed-off-by: NGreg Kroah-Hartman <gregkh@suse.de>

Update the CDC-ACM gadget code to support the peripheral-to-host
notifications when the tty is opened or closed, or issues a BREAK.
The serial framework code calls new generic hooks; right now only
CDC-ACM uses those hooks.  This resolves several REVISIT comments
in the code.  (Based on a patch from Felipe Balbi.)

Note that this doesn't expose USB_CDC_CAP_BRK to the host, since
this code still rejects USB_CDC_REQ_SEND_BREAK control requests
for host-to-peripheral BREAK signaling (received via /dev/ttyGS*).
Signed-off-by: NDavid Brownell <dbrownell@users.sourceforge.net>
Cc: Felipe Balbi <felipe.balbi@nokia.com>
Signed-off-by: NGreg Kroah-Hartman <gregkh@suse.de>

This switches the serial gadget over to using the new "function"
versions of the serial port interfacing code.  The remaining code
in the main source file is quite small...
Signed-off-by: NDavid Brownell <dbrownell@users.sourceforge.net>
Signed-off-by: NGreg Kroah-Hartman <gregkh@suse.de>

Split out the generic serial support into a "function driver".  This
closely mimics the ACM support, but with a MUCH simpler control model.
Signed-off-by: NDavid Brownell <dbrownell@users.sourceforge.net>
Signed-off-by: NGreg Kroah-Hartman <gregkh@suse.de>

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: NDavid Brownell <dbrownell@users.sourceforge.net>
Signed-off-by: NGreg Kroah-Hartman <gregkh@suse.de>

This abstracts the "gadget serial" driver TTY glue into a separate
component, cleaning it up and disentangling it from connection state.

It also changed some behaviors for the better:

  - Stops using "experimental" major #127, and switches over to
    having the TTY layer allocate the dev_t numbers.
    
  - Provides /sys/class/tty/ttyGS* nodes, thus mdev/udev support.
    (Note "mdev" hotplug bug in Busybox v1.7.2: /dev/ttyGS0 will
    be a *block* device without CONFIG_SYSFS_DEPRECATED_V2.)

  - The tty nodes no longer reject opens when there's no host.
    Now they can support normal getty configs in /etc/inttab...

  - Now implements RX throttling.  When the line discipline says
    it doesn't want any more data, only packets in flight will be
    delivered (currently, max 1K/8K at full/high speeds) until it
    unthrottles the data.

  - Supports low_latency.  This is a good policy for all USB serial
    adapters, since it eliminates scheduler overhead on RX paths.

This also includes much cleanup including better comments, fixing
memory leaks and other bugs (including some locking fixes), messaging
cleanup, and an interface audit and tightening.  This added up to a
significant object code shrinkage, on the order of 20% (!) depending
on CPU and compiler.

A separate patch actually kicks in this new code, using the functions
declared in this new header, and removes the previous glue.
Signed-off-by: NDavid Brownell <dbrownell@users.sourceforge.net>
Signed-off-by: NGreg Kroah-Hartman <gregkh@suse.de>