linux-stable.git/drivers/tty, branch v5.16.9

tty: Add support for Brainboxes UC cards.

2022-02-01T16:29:07+00:00

commit 152d1afa834c84530828ee031cf07a00e0fc0b8c upstream.

This commit adds support for the some of the Brainboxes PCI range of
cards, including the UC-101, UC-235/246, UC-257, UC-268, UC-275/279,
UC-302, UC-310, UC-313, UC-320/324, UC-346, UC-357, UC-368
and UC-420/431.

Signed-off-by: Cameron Williams 
Cc: stable 
Link: https://lore.kernel.org/r/AM5PR0202MB2564688493F7DD9B9C610827C45E9@AM5PR0202MB2564.eurprd02.prod.outlook.com
Signed-off-by: Greg Kroah-Hartman

tty: n_gsm: fix SW flow control encoding/handling

2022-02-01T16:29:06+00:00

commit 8838b2af23caf1ff0610caef2795d6668a013b2d upstream.

n_gsm is based on the 3GPP 07.010 and its newer version is the 3GPP 27.010.
See https://portal.3gpp.org/desktopmodules/Specifications/SpecificationDetails.aspx?specificationId=1516
The changes from 07.010 to 27.010 are non-functional. Therefore, I refer to
the newer 27.010 here. Chapter 5.2.7.3 states that DC1 (XON) and DC3 (XOFF)
are the control characters defined in ISO/IEC 646. These shall be quoted if
seen in the data stream to avoid interpretation as flow control characters.

ISO/IEC 646 refers to the set of ISO standards described as the ISO
7-bit coded character set for information interchange. Its final version
is also known as ITU T.50.
See https://www.itu.int/rec/T-REC-T.50-199209-I/en

To abide the standard it is needed to quote DC1 and DC3 correctly if these
are seen as data bytes and not as control characters. The current
implementation already tries to enforce this but fails to catch all
defined cases. 3GPP 27.010 chapter 5.2.7.3 clearly states that the most
significant bit shall be ignored for DC1 and DC3 handling. The current
implementation handles only the case with the most significant bit set 0.
Cases in which DC1 and DC3 have the most significant bit set 1 are left
unhandled.

This patch fixes this by masking the data bytes with ISO_IEC_646_MASK (only
the 7 least significant bits set 1) before comparing them with XON
(a.k.a. DC1) and XOFF (a.k.a. DC3) when testing which byte values need
quotation via byte stuffing.

Fixes: e1eaea46bb40 ("tty: n_gsm line discipline")
Cc: stable@vger.kernel.org
Signed-off-by: Daniel Starke 
Link: https://lore.kernel.org/r/20220120101857.2509-1-daniel.starke@siemens.com
Signed-off-by: Greg Kroah-Hartman

tty: rpmsg: Fix race condition releasing tty port

2022-02-01T16:29:06+00:00

commit db7f19c0aa0abcb751ff0ed694a071363f702b1d upstream.

The tty_port struct is part of the rpmsg_tty_port structure.
The issue is that the rpmsg_tty_port structure is freed on
rpmsg_tty_remove while it is still referenced in the tty_struct.
Its release is not predictable due to workqueues.

For instance following ftrace shows that rpmsg_tty_close is called after
rpmsg_tty_release_cport:

     nr_test.sh-389     [000] .....   212.093752: rpmsg_tty_remove <-rpmsg_dev_
remove
             cat-1191    [001] .....   212.095697: tty_release <-__fput
      nr_test.sh-389     [000] .....   212.099166: rpmsg_tty_release_cport <-rpm
sg_tty_remove
             cat-1191    [001] .....   212.115352: rpmsg_tty_close <-tty_release
             cat-1191    [001] .....   212.115371: release_tty <-tty_release_str

As consequence, the port must be free only when user has released the TTY
interface.

This path :
- Introduce the .destruct port tty ops function to release the allocated
  rpmsg_tty_port structure.
- Introduce the .hangup tty ops function to call tty_port_hangup.
- Manages the tty port refcounting to trig the .destruct port ops,
- Introduces the rpmsg_tty_cleanup function to ensure that the TTY is
  removed before decreasing the port refcount.

Fixes: 7c0408d80579 ("tty: add rpmsg driver")
Cc: stable 
Signed-off-by: Arnaud Pouliquen 
Link: https://lore.kernel.org/r/20220104163545.34710-1-arnaud.pouliquen@foss.st.com
Signed-off-by: Greg Kroah-Hartman

serial: stm32: fix software flow control transfer

2022-02-01T16:29:06+00:00

commit 037b91ec7729524107982e36ec4b40f9b174f7a2 upstream.

x_char is ignored by stm32_usart_start_tx() when xmit buffer is empty.

Fix start_tx condition to allow x_char to be sent.

Fixes: 48a6092fb41f ("serial: stm32-usart: Add STM32 USART Driver")
Cc: stable 
Signed-off-by: Erwan Le Ray 
Signed-off-by: Valentin Caron 
Link: https://lore.kernel.org/r/20220111164441.6178-3-valentin.caron@foss.st.com
Signed-off-by: Greg Kroah-Hartman

serial: 8250: of: Fix mapped region size when using reg-offset property

2022-02-01T16:29:06+00:00

commit d06b1cf28297e27127d3da54753a3a01a2fa2f28 upstream.

8250_of supports a reg-offset property which is intended to handle
cases where the device registers start at an offset inside the region
of memory allocated to the device. The Xilinx 16550 UART, for which this
support was initially added, requires this. However, the code did not
adjust the overall size of the mapped region accordingly, causing the
driver to request an area of memory past the end of the device's
allocation. For example, if the UART was allocated an address of
0xb0130000, size of 0x10000 and reg-offset of 0x1000 in the device
tree, the region of memory reserved was b0131000-b0140fff, which caused
the driver for the region starting at b0140000 to fail to probe.

Fix this by subtracting reg-offset from the mapped region size.

Fixes: b912b5e2cfb3 ([POWERPC] Xilinx: of_serial support for Xilinx uart 16550.)
Cc: stable 
Signed-off-by: Robert Hancock 
Link: https://lore.kernel.org/r/20220112194214.881844-1-robert.hancock@calian.com
Signed-off-by: Greg Kroah-Hartman

serial: pl011: Fix incorrect rs485 RTS polarity on set_mctrl

2022-02-01T16:29:06+00:00

commit 62f676ff7898f6c1bd26ce014564773a3dc00601 upstream.

Commit 8d479237727c ("serial: amba-pl011: add RS485 support") sought to
keep RTS deasserted on set_mctrl if rs485 is enabled.  However it did so
only if deasserted RTS polarity is high.  Fix it in case it's low.

Fixes: 8d479237727c ("serial: amba-pl011: add RS485 support")
Cc: stable@vger.kernel.org # v5.15+
Cc: Lino Sanfilippo 
Signed-off-by: Jochen Mades 
[lukas: copyedit commit message, add stable designation]
Signed-off-by: Lukas Wunner 
Link: https://lore.kernel.org/r/85fa3323ba8c307943969b7343e23f34c3e652ba.1642909284.git.lukas@wunner.de
Signed-off-by: Greg Kroah-Hartman

serial: Fix incorrect rs485 polarity on uart open

2022-01-27T11:02:44+00:00

commit d3b3404df318504ec084213ab1065b73f49b0f1d upstream.

Commit a6845e1e1b78 ("serial: core: Consider rs485 settings to drive
RTS") sought to deassert RTS when opening an rs485-enabled uart port.
That way, the transceiver does not occupy the bus until it transmits
data.

Unfortunately, the commit mixed up the logic and *asserted* RTS instead
of *deasserting* it:

The commit amended uart_port_dtr_rts(), which raises DTR and RTS when
opening an rs232 port.  "Raising" actually means lowering the signal
that's coming out of the uart, because an rs232 transceiver not only
changes a signal's voltage level, it also *inverts* the signal.  See
the simplified schematic in the MAX232 datasheet for an example:
https://www.ti.com/lit/ds/symlink/max232.pdf

So, to raise RTS on an rs232 port, TIOCM_RTS is *set* in port->mctrl
and that results in the signal being driven low.

In contrast to rs232, the signal level for rs485 Transmit Enable is the
identity, not the inversion:  If the transceiver expects a "high" RTS
signal for Transmit Enable, the signal coming out of the uart must also
be high, so TIOCM_RTS must be *cleared* in port->mctrl.

The commit did the exact opposite, but it's easy to see why given the
confusing semantics of rs232 and rs485.  Fix it.

Fixes: a6845e1e1b78 ("serial: core: Consider rs485 settings to drive RTS")
Cc: stable@vger.kernel.org # v4.14+
Cc: Rafael Gago Castano 
Cc: Jan Kiszka 
Cc: Su Bao Cheng 
Signed-off-by: Lukas Wunner 
Link: https://lore.kernel.org/r/9395767847833f2f3193c49cde38501eeb3b5669.1639821059.git.lukas@wunner.de
Signed-off-by: Greg Kroah-Hartman

serial: core: Keep mctrl register state and cached copy in sync

2022-01-27T11:02:31+00:00

[ Upstream commit 93a770b7e16772530196674ffc79bb13fa927dc6 ]

struct uart_port contains a cached copy of the Modem Control signals.
It is used to skip register writes in uart_update_mctrl() if the new
signal state equals the old signal state.  It also avoids a register
read to obtain the current state of output signals.

When a uart_port is registered, uart_configure_port() changes signal
state but neglects to keep the cached copy in sync.  That may cause
a subsequent register write to be incorrectly skipped.  Fix it before
it trips somebody up.

This behavior has been present ever since the serial core was introduced
in 2002:
https://git.kernel.org/history/history/c/33c0d1b0c3eb

So far it was never an issue because the cached copy is initialized to 0
by kzalloc() and when uart_configure_port() is executed, at most DTR has
been set by uart_set_options() or sunsu_console_setup().  Therefore,
a stable designation seems unnecessary.

Signed-off-by: Lukas Wunner 
Link: https://lore.kernel.org/r/bceeaba030b028ed810272d55d5fc6f3656ddddb.1641129752.git.lukas@wunner.de
Signed-off-by: Greg Kroah-Hartman 
Signed-off-by: Sasha Levin

serial: pl011: Drop CR register reset on set_termios

2022-01-27T11:02:31+00:00

[ Upstream commit e368cc656fd6d0075f1c3ab9676e2001451e3e04 ]

pl011_set_termios() briefly resets the CR register to zero, thereby
glitching DTR/RTS signals.  With rs485 this may result in the bus being
occupied for no reason.

Where does this register write originate from?

The PL011 driver was forked from the PL010 driver in 2004:
https://git.kernel.org/history/history/c/157c0342e591

Until this commit, the PL010 driver's IRQ handler ambauart_int()
modified the CR register without holding the port spinlock.

ambauart_set_termios() also modified that register.  To prevent
concurrent read-modify-writes by the IRQ handler and to prevent
transmission while changing baudrate, ambauart_set_termios() had to
disable interrupts.  On the PL010, that is achieved by writing zero to
the CR register.

However, on the PL011, interrupts are disabled in the IMSC register,
not in the CR register.

Additionally, the commit amended both the PL010 and PL011 driver to
acquire the port spinlock in the IRQ handler, obviating the need to
disable interrupts in ->set_termios().

So the CR register write is obsolete for two reasons.  Drop it.

Cc: Russell King 
Signed-off-by: Lukas Wunner 
Link: https://lore.kernel.org/r/f49f945375f5ccb979893c49f1129f51651ac738.1641129062.git.lukas@wunner.de
Signed-off-by: Greg Kroah-Hartman 
Signed-off-by: Sasha Levin

serial: pl010: Drop CR register reset on set_termios

2022-01-27T11:02:31+00:00

[ Upstream commit 08a0c6dff91c965e39905cf200d22db989203ccb ]

pl010_set_termios() briefly resets the CR register to zero.

Where does this register write come from?

The PL010 driver's IRQ handler ambauart_int() originally modified the CR
register without holding the port spinlock.  ambauart_set_termios() also
modified that register.  To prevent concurrent read-modify-writes by the
IRQ handler and to prevent transmission while changing baudrate,
ambauart_set_termios() had to disable interrupts.  That is achieved by
writing zero to the CR register.

However in 2004 the PL010 driver was amended to acquire the port
spinlock in the IRQ handler, obviating the need to disable interrupts in
->set_termios():
https://git.kernel.org/history/history/c/157c0342e591

That rendered the CR register write obsolete.  Drop it.

Cc: Russell King 
Signed-off-by: Lukas Wunner 
Link: https://lore.kernel.org/r/fcaff16e5b1abb4cc3da5a2879ac13f278b99ed0.1641128728.git.lukas@wunner.de
Signed-off-by: Greg Kroah-Hartman 
Signed-off-by: Sasha Levin