FTDI devices use a receive latency timer to periodically empty the
receive buffer and report modem and line status (also when the buffer is
empty).

When a break or error condition is detected the corresponding status
flags will be set on a packet with nonzero data payload and the flags
are not updated until the break is over or further characters are
received.

In order to avoid over-reporting break and error conditions, these flags
must therefore only be processed for packets with payload.

This specifically fixes the case where after an overrun, the error
condition is continuously reported and NULL-characters inserted until
further data is received.
Reported-by: Michael Walle <michael@walle.cc>
Fixes: 72fda3ca ("USB: serial: ftd_sio: implement sysrq handling on
break")
Fixes: 166ceb69 ("USB: ftdi_sio: clean up line-status handling")
Cc: stable <stable@vger.kernel.org>	# v2.6.35
Signed-off-by: Johan Hovold <johan@kernel.org>

Add new USB IDs for cp2104/5 devices on Bx50v3 boards due to the design
change.
Signed-off-by: Ken Lin <yungching0725@gmail.com>
Cc: stable <stable@vger.kernel.org>
Signed-off-by: Johan Hovold <johan@kernel.org>

Make sure to check for short transfers before parsing the receive buffer
to avoid acting on stale data.

Fixes: 1da177e4 ("Linux-2.6.12-rc2")
Reviewed-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Johan Hovold <johan@kernel.org>

Make sure the received data has the required headers before parsing it.

Also drop the redundant urb-status check, which has already been handled
by the caller.

Fixes: 1da177e4 ("Linux-2.6.12-rc2")
Reviewed-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Johan Hovold <johan@kernel.org>

Make sure to check for short transfers to avoid underflow in a loop
condition when parsing the receive buffer.

Also fix an off-by-one error in the incomplete sanity check which could
lead to invalid data being parsed.

Fixes: 8c209e67 ("USB: make actual_length in struct urb field u32")
Fixes: 1da177e4 ("Linux-2.6.12-rc2")
Cc: stable <stable@vger.kernel.org>	# v2.6.30
Reviewed-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Johan Hovold <johan@kernel.org>

Use the port device rather than usb device in info and error messages.

This makes sure that driver and tty port is included in the messages,
while also making them more uniform.
Reviewed-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Johan Hovold <johan@kernel.org>

Remove redundant check of num_interrupt_in which has already been
verified in probe (killing a NULL-urb would also have been fine).
Reviewed-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Johan Hovold <johan@kernel.org>

Return -ENODEV rather than -EINVAL on probe errors due to a missing
endpoint.

Also clean up the endpoint sanity check somewhat and use the interface
device for logging a more compact error in case an expected endpoint is
missing.
Reviewed-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Johan Hovold <johan@kernel.org>

The adaptor can be found on development boards for 78k, RL78 and V850
microcontrollers produced by Renesas Electronics Corporation.

This is not a full-featured USB to serial converter, however it allows
basic communication and simple control which is enough for programming of
on-board flash and debugging through a debug monitor.

uPD78F0730 is a USB-enabled microcontroller with USB-to-UART conversion
implemented in firmware.

This chip is also present in some debugging adaptors which use it for
USB-to-SPI conversion as well. The present driver doesn't cover SPI,
only USB-to-UART conversion is supported.
Signed-off-by: Maksim Salau <maksim.salau@gmail.com>
Signed-off-by: Johan Hovold <johan@kernel.org>

Do not report ASYNC_SKIP_TEST or ASYNC_AUTO_IRQ as being set in
TIOCGSERIAL handlers as these flags are not supported and do not really
make any sense for USB serial devices in the first place.
Reviewed-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Johan Hovold <johan@kernel.org>

Clean up the ioctl handler and make sure to pass an unsigned-int rather
than serial_struct pointer to the TIOCSERGETLSR helper as this it what
the user argument really is.
Reviewed-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Johan Hovold <johan@kernel.org>

Since commit 557aaa7f ("ft232: support the ASYNC_LOW_LATENCY
flag") the FTDI driver has been using a receive latency-timer value of
1 ms instead of the device default of 16 ms.

The latency timer is used to periodically empty a non-full receive
buffer, but a status header is always sent when the timer expires
including when the buffer is empty. This means that a two-byte bulk
message is received every millisecond also for an otherwise idle port as
long as it is open.

Let's restore the pre-2009 behaviour which reduces the rate of the
status messages to 1/16th (e.g. interrupt frequency drops from 1 kHz to
62.5 Hz) by not setting ASYNC_LOW_LATENCY by default.

Anyone willing to pay the price for the minimum-latency behaviour should
set the flag explicitly instead using the TIOCSSERIAL ioctl or a tool
such as setserial (e.g. setserial /dev/ttyUSB0 low_latency).

Note that since commit 0cbd81a9 ("USB: ftdi_sio: remove
tty->low_latency") the ASYNC_LOW_LATENCY flag has no other effects but
to set a minimal latency timer.
Reported-by: Antoine Aubert <a.aubert@overkiz.com>
Fixes: 557aaa7f ("ft232: support the ASYNC_LOW_LATENCY flag")
Cc: stable@vger.kernel.org # v2.6.31: e3e574adSigned-off-by: Johan Hovold <johan@kernel.org>

The opticon driver used a control request at open to trigger a CTS
status notification to be sent over the bulk-in pipe. When the driver
was converted to using the generic read implementation, an inverted test
prevented this request from being sent, something which could lead to
TIOCMGET reporting an incorrect CTS state.
Reported-by: Dan Carpenter <dan.carpenter@oracle.com>
Fixes: 7a6ee2b0 ("USB: opticon: switch to generic read
implementation")
Cc: stable <stable@vger.kernel.org>
Reviewed-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Johan Hovold <johan@kernel.org>

Make sure to detect and return an error on zero-length control-message
transfers when reading from the device.

This addresses a potential failure to detect an empty transmit buffer
during close.

Also remove a redundant check for short transfer when sending a command.

Fixes: 1da177e4 ("Linux-2.6.12-rc2")
Reviewed-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Johan Hovold <johan@kernel.org>

Make sure to detect short control-message transfers rather than continue
with zero-initialised data when retrieving modem status and during
device initialisation.

Fixes: 52af9545 ("USB: add USB serial ssu100 driver")
Reviewed-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Johan Hovold <johan@kernel.org>

Make sure to detect short control transfers and return zero on success
when retrieving the modem status.

This fixes the TIOCMGET implementation which since e1ed212d ("USB:
spcp8x5: add proper modem-status support") has returned TIOCM_LE on
successful retrieval, and avoids leaking bits from the stack on short
transfers.

This also fixes the carrier-detect implementation which since the above
mentioned commit unconditionally has returned true.

Fixes: e1ed212d ("USB: spcp8x5: add proper modem-status support")
Cc: stable <stable@vger.kernel.org>
Reviewed-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Johan Hovold <johan@kernel.org>

Make sure to detect short control-message transfers when fetching
modem and line state in open and when retrieving registers.

This specifically makes sure that an errno is returned to user space on
errors in TIOCMGET instead of a zero bitmask.

Also drop the unused getdevice function which also lacked appropriate
error handling.

Fixes: f7a33e60 ("USB: serial: add quatech2 usb to serial driver")
Reviewed-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Johan Hovold <johan@kernel.org>

Make sure to return an error on zero-length transfers when retrieving
the line settings even if the driver currently ignores the return value.

Also remove a redundant check for short transfer when setting the line
settings.
Reviewed-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Johan Hovold <johan@kernel.org>

Make sure to detect short transfers when reading a device register.

The modem-status handling had sufficient error checks in place, but move
handling of short transfers into the register accessor function itself
for consistency.
Reviewed-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Johan Hovold <johan@kernel.org>

Make sure to log an error on short transfers when reading a device
register.

Also clear the provided buffer (which if often an uninitialised
automatic variable) on errors as the driver currently does not bother to
check for errors.
Reviewed-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Johan Hovold <johan@kernel.org>

Make sure to detect short control-message transfers so that errors are
logged when reading the modem status at open.

Note that while this also avoids initialising the modem status using
uninitialised heap data, these bits could not leak to user space as they
are currently not used.

Fixes: 1da177e4 ("Linux-2.6.12-rc2")
Reviewed-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Johan Hovold <johan@kernel.org>

Remove code that allocated but never used a buffer during open.
Reviewed-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Johan Hovold <johan@kernel.org>

Make sure to detect short control-message transfers and log an error
when reading incomplete manufacturer and boot descriptors.

Note that the default all-zero descriptors will now be used after a
short transfer is detected instead of partially initialised ones.

Fixes: 1da177e4 ("Linux-2.6.12-rc2")
Reviewed-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Johan Hovold <johan@kernel.org>

Use a dedicated buffer for the DMA transfer and make sure to detect
short transfers to avoid parsing a corrupt descriptor.

Fixes: 6e8cf775 ("USB: add EPIC support to the io_edgeport driver")
Reviewed-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Johan Hovold <johan@kernel.org>

Make sure to detect short responses when reading the latency timer to
avoid using stale buffer data.

Note that no heap data would currently leak through sysfs as
ASYNC_LOW_LATENCY is set by default.

Fixes: 1da177e4 ("Linux-2.6.12-rc2")
Reviewed-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Johan Hovold <johan@kernel.org>

Make sure to detect short responses when fetching the modem status in
order to avoid parsing uninitialised buffer data and having bits of it
leak to user space.

Note that we still allow for short 1-byte responses.

Fixes: 1da177e4 ("Linux-2.6.12-rc2")
Cc: stable <stable@vger.kernel.org>
Reviewed-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Johan Hovold <johan@kernel.org>

Fix open error handling which failed to detect errors when reading the
MSR and LSR registers, something which could lead to the shadow
registers being initialised from errnos.

Note that calling the generic close implementation is sufficient in the
error paths as the interrupt urb has not yet been submitted and the
register updates have not been made.

Fixes: f4c1e8d5 ("USB: ark3116: Make existing functions 16450-aware
and add close and release functions.")
Reviewed-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Johan Hovold <johan@kernel.org>

The current implementation failed to detect short transfers, something
which could lead to bits of the uninitialised heap transfer buffer
leaking to user space.

Fixes: 149fc791 ("USB: ark3116: Setup some basic infrastructure for
new ark3116 driver.")
Fixes: f4c1e8d5 ("USB: ark3116: Make existing functions 16450-aware
and add close and release functions.")
Cc: stable <stable@vger.kernel.org>
Reviewed-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Johan Hovold <johan@kernel.org>

Remove unused termios structure from private data that was left by an
earlier purge by commit b1cff285 ("usb serial: Eliminate bogus ioctl
code").
Reviewed-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Johan Hovold <johan@kernel.org>

Drop redundant packed attribute from the port-settings struct which is
already 1-byte aligned. Also replace __u8 with u8 for the field types as
this is not a structure we share with user space.
Reviewed-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Johan Hovold <johan@kernel.org>

Remove dead and broken code that only served as a reminder to one day
implement modem control.
Reviewed-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Johan Hovold <johan@kernel.org>

Replace a couple of dev_info with dev_dbg and remove another.

Also use the port device for logging, and include a radix prefix when
logging the baudrate.
Reviewed-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Johan Hovold <johan@kernel.org>

Some CH340 devices appear unable to change the initial LCR settings, so
set a sane 8N1 default during probe to enable basic support for such
devices.

Also drop a redundant LCR read during device initialisation.
Signed-off-by: Johan Hovold <johan@kernel.org>

Rename the line-control-register variable in set_termios to "lcr" and
use u8 type to match the shadow register.
Signed-off-by: Johan Hovold <johan@kernel.org>

Rename the shadow modem-status register currently named "line_status" to
the less confusing "msr".

Also rename the helper function used to parse the interrupt data.
Signed-off-by: Johan Hovold <johan@kernel.org>

Rename the shadow modem-control register currently named "line_control"
to the less confusing "mcr".
Signed-off-by: Johan Hovold <johan@kernel.org>

Clean up the control-transfer debug messages by dropping redundant
information and unnecessary casts.
Signed-off-by: Johan Hovold <johan@kernel.org>

The modem-status register was read as part of device configuration at
port_probe and then again at open (and reset-resume). During open (and
reset-resume) the MSR was read before submitting the interrupt URB,
something which could lead to an MSR-change going unnoticed when it
races with open (reset-resume).

Fix this by dropping the redundant reconfiguration of the port at every
open, and only read the MSR after the interrupt URB has been submitted.

Fixes: 664d5df9 ("USB: usb-serial ch341: support for DTR/RTS/CTS")
Signed-off-by: Johan Hovold <johan@kernel.org>

The variable havedata was only being set but never used afterwards.
Signed-off-by: Sudip Mukherjee <sudip.mukherjee@codethink.co.uk>
Signed-off-by: Johan Hovold <johan@kernel.org>