Modules registering drivers with usb_serial_register_drivers() might
forget to set .owner field.  The field is used by some of other kernel
parts for reference counting (try_module_get()), so it is expected that
drivers will set it.

Solve the problem by moving this task away from the drivers to the core
USB serial code, just like we did for platform_driver in
commit 9447057eaff8 ("platform_device: use a macro instead of
platform_driver_register").

Signed-off-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
[ johan: amend commit summary ]
Signed-off-by: Johan Hovold <johan@kernel.org>

Start propagating errors to user space when setting the break state
fails.

This will be used by follow-on changes to also report when a driver or
device does not support break control.

Tested-by: Corey Minyard <cminyard@mvista.com>
Signed-off-by: Johan Hovold <johan@kernel.org>

Now that the driver core can properly handle constant struct bus_type,
move all of the USB subsystem struct bus_type structures as const,
placing them into read-only memory which can not be modified at runtime.

Cc: Johan Hovold <johan@kernel.org>
Cc: Evan Green <evgreen@chromium.org>
Cc: Alan Stern <stern@rowland.harvard.edu>
Cc: linux-usb@vger.kernel.org
Acked-by: Heikki Krogerus <heikki.krogerus@linux.intel.com>
Link: https://lore.kernel.org/r/20230313182918.1312597-36-gregkh@linuxfoundation.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

There should be no reason to adjust old ktermios which is going to get
discarded anyway.

Reviewed-by: Andy Shevchenko <andy.shevchenko@gmail.com>
Signed-off-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>
Link: https://lore.kernel.org/r/20220816115739.10928-8-ilpo.jarvinen@linux.intel.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

All these files have been updated in the commit given in the Fixes: tag
below.

When the SPDX-License-Identifier: has been added, the corresponding text at
the beginning of the files has not been deleted.
All these texts are about GPL-2.0, with different variation in the wording.

Remove these now useless lines to save some LoC.

Fixes: 5fd54ace4721 ("USB: add SPDX identifiers to all remaining files in drivers/usb/")
Signed-off-by: Christophe JAILLET <christophe.jaillet@wanadoo.fr>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Johan writes:

USB-serial updates for 5.14-rc1

Here are the USB-serial updates for 5.14-rc1, including:

 - gpio support for CP2108
 - chars_in_buffer and write_room return-value updates
 - chars_in_buffer and write_room clean ups

Included are also various clean ups.

All have been in linux-next with no reported issues.

* tag 'usb-serial-5.14-rc1' of https://git.kernel.org/pub/scm/linux/kernel/git/johan/usb-serial:
  USB: serial: cp210x: add support for GPIOs on CP2108
  USB: serial: drop irq-flags initialisations
  USB: serial: mos7840: drop buffer-callback return-value comments
  USB: serial: mos7720: drop buffer-callback sanity checks
  USB: serial: io_edgeport: drop buffer-callback sanity checks
  USB: serial: digi_acceleport: add chars_in_buffer locking
  USB: serial: digi_acceleport: reduce chars_in_buffer over-reporting
  USB: serial: make usb_serial_driver::chars_in_buffer return uint
  USB: serial: make usb_serial_driver::write_room return uint

Fix some spelling mistakes in comments:
trasfer ==> transfer
consumtion ==> consumption
endoint ==> endpoint
sharable ==> shareable
contraints ==> constraints
Auxilary ==> Auxiliary
correspondig ==> corresponding
interupt ==> interrupt
inifinite ==> infinite
assignement ==> assignment

Signed-off-by: Zhen Lei <thunder.leizhen@huawei.com>
Link: https://lore.kernel.org/r/20210517094020.7310-1-thunder.leizhen@huawei.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

tty_operations::chars_in_buffer is being switched to return uint. Do the
same for usb_serial_driver's chars_in_buffer.

Signed-off-by: Jiri Slaby <jslaby@suse.cz>
[ johan: amend commit message ]
Signed-off-by: Johan Hovold <johan@kernel.org>

Line disciplines expect a positive value or zero returned from
tty->ops->write_room (invoked by tty_write_room). Both of them are being
updated to return an unsigned int. Switch also
usb_serial_driver::write_room and all its users.

Signed-off-by: Jiri Slaby <jslaby@suse.cz>
[ johan: amend commit message, drop unrelated comment change ]
Signed-off-by: Johan Hovold <johan@kernel.org>

TIOCSSERIAL is a horrid, underspecified, legacy interface which for most
serial devices is only useful for setting the close_delay and
closing_wait parameters.

The closing_wait parameter determines how long to wait for the transfer
buffers to drain during close and the default timeout of 30 seconds may
not be sufficient at low line speeds. In other cases, when for example
flow is stopped, the default timeout may instead be too long.

Add generic support for TIOCSSERIAL and TIOCGSERIAL with handling of the
three common parameters close_delay, closing_wait and line for the
benefit of all USB serial drivers while still allowing drivers to
implement further functionality through the existing callbacks.

This currently includes a few drivers that report their base baud clock
rate even if that is really only of interest when setting custom
divisors through the deprecated ASYNC_SPD_CUST interface; an interface
which only the FTDI driver actually implements.

Some drivers have also been reporting back a fake UART type, something
which should no longer be needed and will be dropped by a follow-on
patch.

Reviewed-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Johan Hovold <johan@kernel.org>