The counts in tty_port_client_operations hooks' are currently
represented by all 'int', 'unsigned int', and 'size_t'. Unify them all
to unsigned 'size_t' for clarity. Note that size_t is used already in
tty_buffer.c. So, eventually, it is spread for counts everywhere and
this is the beginning.

So the two changes namely:
* ::receive_buf() is called from tty_ldisc_receive_buf(). And that
  expects values ">= 0" from ::receive_buf(), so switch its rettype to
  size_t is fine. tty_ldisc_receive_buf() types will be changed
  separately.
* ::lookahead_buf()'s count comes from lookahead_bufs() and is already
  'unsigned int'.

Signed-off-by: "Jiri Slaby (SUSE)" <jirislaby@kernel.org>
Cc: Rob Herring <robh@kernel.org>
Link: https://lore.kernel.org/r/20230810091510.13006-11-jirislaby@kernel.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

The parameters are already unsigned chars. So make them explicitly u8s,
as the rest is going to be unified to u8 eventually too.

Signed-off-by: "Jiri Slaby (SUSE)" <jirislaby@kernel.org>
Cc: Rob Herring <robh@kernel.org>
Link: https://lore.kernel.org/r/20230810091510.13006-10-jirislaby@kernel.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Adds serdev_device_break_ctl() and an implementation for ttyport.
This function simply calls the break_ctl in tty layer, which can
assert a break signal over UART-TX line, if the tty and the
underlying platform and UART peripheral supports this operation.

Signed-off-by: Neeraj Sanjay Kale <neeraj.sanjaykale@nxp.com>
Reviewed-by: Simon Horman <simon.horman@corigine.com>
Signed-off-by: Luiz Augusto von Dentz <luiz.von.dentz@intel.com>

This replaces all instances of ENOTSUPP with EOPNOTSUPP since ENOTSUPP
is not a standard error code. This will help maintain consistency in
error codes when new serdev API's are added.

Signed-off-by: Neeraj Sanjay Kale <neeraj.sanjaykale@nxp.com>
Reviewed-by: Simon Horman <simon.horman@corigine.com>
Signed-off-by: Luiz Augusto von Dentz <luiz.von.dentz@intel.com>

The serdev tty-port controller driver should reset the tty-port client
operations also on deregistration to avoid a NULL-pointer dereference in
case the port is later re-registered as a normal tty device.

Note that this can only happen with tty drivers such as 8250 which have
statically allocated port structures that can end up being reused and
where a later registration would not register a serdev controller (e.g.
due to registration errors or if the devicetree has been changed in
between).

Specifically, this can be an issue for any statically defined ports that
would be registered by 8250 core when an 8250 driver is being unbound.

Fixes: bed35c6dfa6a ("serdev: add a tty port controller driver")
Cc: stable <stable@vger.kernel.org>     # 4.11
Reported-by: Loic Poulain <loic.poulain@linaro.org>
Signed-off-by: Johan Hovold <johan@kernel.org>
Link: https://lore.kernel.org/r/20200210145730.22762-1-johan@kernel.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

The tty struct holds a pointer to the driver's tty operations so drop
the unnecessary driver dereference when calling tiocmget and tiocmset.

Note that this also makes the calls match the preceding sanity checks as
expected.

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

Pull tty/staging driver updates from Greg KH:
 "Here is the big tty/serial driver update for 4.16-rc1.

  The usual number of various serial driver fixes and updates to try to
  get them to work with crazy hardware configurations (seriously, how
  many different ways are hardware engineers going to come up with to
  hook up a simple UART?)

  There is also some serdev bugfixes and updates, as well as a
  smattering of other small fixes in here.

  All have been in the linux-next tree for a while, with no reported
  issues"

* tag 'tty-4.16-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/tty: (65 commits)
  tty: serial: exar: Relocate sleep wake-up handling
  tty: fix data race between tty_init_dev and flush of buf
  serial: imx: fix endless loop during suspend
  serial: core: mark port as initialized after successful IRQ change
  serdev: only match serdev devices
  serdev: do not generate modaliases for controllers
  serial: mxs-auart: don't use GPIOF_* with gpiod_get_direction
  serial: 8250_dw: Revert "Improve clock rate setting"
  MAINTAINERS: Add myself as designated reviewer for 8250_dw
  gpio: serial: max310x: Support open-drain configuration for GPIOs
  serdev: Fix serdev_uevent failure on ACPI enumerated serdev-controllers
  serial: 8250_ingenic: Parse earlycon options
  serial: 8250_ingenic: Add support for the JZ4770 SoC
  serial: core: Make uart_parse_options take const char* argument
  serial: 8250_of: fix return code when probe function fails to get reset
  serial: imx: Only wakeup via RTSDEN bit if the system has RTS/CTS
  serial: 8250_uniphier: fix error return code in uniphier_uart_probe()
  tty: n_gsm: Allow ADM response in addition to UA for control dlci
  tty: omap-serial: Fix initial on-boot RTS GPIO level
  tty: serial: jsm: Add one check against NULL pointer dereference
  ...

Adds serdev_device_set_parity() and an implementation for ttyport.
The interface uses an enum with the values SERIAL_PARITY_NONE,
SERIAL_PARITY_EVEN and SERIAL_PARITY_ODD.

Signed-off-by: Ulrich Hecht <ulrich.hecht+renesas@gmail.com>
Reviewed-by: Sebastian Reichel <sebastian.reichel@collabora.co.uk>
Reviewed-by: Johan Hovold <johan@kernel.org>
Acked-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Marcel Holtmann <marcel@holtmann.org>

Serdev does not use the file abstraction and specifically there will
never be anyone polling a file descriptor for POLLOUT events.

Just use plain wake_up_interruptible() in the write_wakeup callback and
document why it's there.

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

We want the serial/tty fixes in here as well.

Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>