The direction of the pipe argument must match the request-type direction
bit or control requests may fail depending on the host-controller-driver
implementation.

Fix the three requests which erroneously used usb_rcvctrlpipe().

Fixes: f7a33e608d9a ("USB: serial: add quatech2 usb to serial driver")
Cc: stable@vger.kernel.org      # 3.5
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>

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 xmit_fifo_size parameter could be used to set the hardware transmit
fifo size of a legacy UART when it could not be detected, but the
interface is limited to eight bits and should be left unset when not
used.

Similarly, baud_base could be used to set the UART base clock when it
could not be detected but might as well be left unset when it is not
known.

The close_delay and closing_wait parameters returned by TIOCGSERIAL are
specified in centiseconds (not jiffies). The driver does not yet support
changing these, but let's report back the default values actually used
(0.5 and 30 seconds, respectively).

Fixes: f7a33e608d9a ("USB: serial: add quatech2 usb to serial driver")
Reviewed-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Johan Hovold <johan@kernel.org>

All usb_serial drivers return 0 in their remove callbacks and driver
core ignores the value returned by usb_serial_device_remove(). So change
the remove callback to return void and return 0 unconditionally in
usb_serial_device_remove().

Signed-off-by: Uwe Kleine-König <uwe@kleine-koenig.org>
Link: https://lore.kernel.org/r/20210208143149.963644-2-uwe@kleine-koenig.org
Signed-off-by: Johan Hovold <johan@kernel.org>

Drop two unused stub functions which only served as documentation.

This also avoids a W=1 (-Wunused-but-set-variable) warning.

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

Check for NULL port data in the modem- and line-status handlers to avoid
dereferencing a NULL pointer in the unlikely case where a port device
isn't bound to a driver (e.g. after an allocation failure on port
probe).

Note that the other (stubbed) event handlers qt2_process_xmit_empty()
and qt2_process_flush() would need similar sanity checks in case they
are ever implemented.

Fixes: f7a33e608d9a ("USB: serial: add quatech2 usb to serial driver")
Cc: stable <stable@vger.kernel.org>     # 3.5
Reviewed-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Johan Hovold <johan@kernel.org>

Fixes gcc '-Wunused-but-set-variable' warning:

drivers/usb/serial/quatech2.c: In function 'qt2_process_read_urb':
drivers/usb/serial/quatech2.c:503:27: warning:
 variable 'port_priv' set but not used [-Wunused-but-set-variable]

It not used any more after commit 2be818a116b2 ('Revert "USB: quatech2:
only write to the tty if the port is open."')

Signed-off-by: YueHaibing <yuehaibing@huawei.com>
Signed-off-by: Johan Hovold <johan@kernel.org>

Reviewed-by: Johan Hovold <johan@kernel.org>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

The USB completion callback does not disable interrupts while acquiring
the lock. We want to remove the local_irq_disable() invocation from
__usb_hcd_giveback_urb() and therefore it is required for the callback
handler to disable the interrupts while acquiring the lock.
The callback may be invoked either in IRQ or BH context depending on the
USB host controller.
Use the _irqsave() variant of the locking primitives.

Signed-off-by: John Ogness <john.ogness@linutronix.de>
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Signed-off-by: Johan Hovold <johan@kernel.org>

Negative error code will be larger than sizeof().

Note that none of these bugs prevent errors from being detected, even if
the ir-usb one would cause a less precise debug message to printed.

Signed-off-by: Chengguang Xu <cgxu519@gmx.com>
[ johan: add comment about implications ]
Signed-off-by: Johan Hovold <johan@kernel.org>