linux-stable.git/include/linux/serial_core.h, branch v6.1.172

serial: Make uart_remove_one_port() return void

2026-01-11T14:19:23+00:00

[ Upstream commit d5b3d02d0b107345f2a6ecb5b06f98356f5c97ab ]

The return value is only ever used as a return value for remove callbacks
of platform drivers. This return value is ignored by the driver core.
(The only effect is an error message, but uart_remove_one_port() already
emitted one in this case.)

So the return value isn't used at all and uart_remove_one_port() can be
changed to return void without any loss. Also this better matches the
Linux device model as remove functions are not supposed to fail.

Signed-off-by: Uwe Kleine-König 
Link: https://lore.kernel.org/r/20230512173810.131447-3-u.kleine-koenig@pengutronix.de
Signed-off-by: Greg Kroah-Hartman 
Stable-dep-of: 74098cc06e75 ("xhci: dbgtty: fix device unregister: fixup")
Signed-off-by: Sasha Levin 
Signed-off-by: Greg Kroah-Hartman

serial: Make uart_handle_cts_change() status param bool active

2024-11-01T00:56:02+00:00

[ Upstream commit 968d64578ec92968e8c79d766eb966efd1f68d7e ]

Convert uart_handle_cts_change() to bool which is more appropriate
than unsigned int.

Rename status to active to better describe what the parameter means.
While at it, make the comment about the active parameter easier to
parse.

Cleanup callsites from operations that are not necessary with bool.

Reviewed-by: Jiri Slaby 
Signed-off-by: Ilpo Järvinen 
Link: https://lore.kernel.org/r/20230117090358.4796-10-ilpo.jarvinen@linux.intel.com
Signed-off-by: Greg Kroah-Hartman 
Stable-dep-of: 40d7903386df ("serial: imx: Update mctrl old_status on RTSD interrupt")
Signed-off-by: Sasha Levin

tty/serial: Make ->dcd_change()+uart_handle_dcd_change() status bool active

2024-11-01T00:56:02+00:00

[ Upstream commit 0388a152fc5544be82e736343496f99c4eef8d62 ]

Convert status parameter for ->dcd_change() and
uart_handle_dcd_change() to bool which matches to how the parameter is
used.

Rename status to active to better describe what the parameter means.

Acked-by: Rodolfo Giometti 
Reviewed-by: Jiri Slaby 
Signed-off-by: Ilpo Järvinen 
Link: https://lore.kernel.org/r/20230117090358.4796-9-ilpo.jarvinen@linux.intel.com
Signed-off-by: Greg Kroah-Hartman 
Stable-dep-of: 40d7903386df ("serial: imx: Update mctrl old_status on RTSD interrupt")
Signed-off-by: Sasha Levin

serial: core: Add UPIO_UNKNOWN constant for unknown port type

2024-06-21T12:36:00+00:00

[ Upstream commit 79d713baf63c8f23cc58b304c40be33d64a12aaf ]

In some APIs we would like to assign the special value to iotype
and compare against it in another places. Introduce UPIO_UNKNOWN
for this purpose.

Note, we can't use 0, because it's a valid value for IO port access.

Signed-off-by: Andy Shevchenko 
Link: https://lore.kernel.org/r/20240304123035.758700-3-andriy.shevchenko@linux.intel.com
Signed-off-by: Greg Kroah-Hartman 
Stable-dep-of: 87d80bfbd577 ("serial: 8250_dw: Don't use struct dw8250_data outside of 8250_dw")
Signed-off-by: Sasha Levin

serial: core: fix kernel-doc for uart_port_unlock_irqrestore()

2024-02-01T00:17:12+00:00

commit 29bff582b74ed0bdb7e6986482ad9e6799ea4d2f upstream.

Fix the function name to avoid a kernel-doc warning:

include/linux/serial_core.h:666: warning: expecting prototype for uart_port_lock_irqrestore(). Prototype was for uart_port_unlock_irqrestore() instead

Fixes: b0af4bcb4946 ("serial: core: Provide port lock wrappers")
Signed-off-by: Randy Dunlap 
Cc: Thomas Gleixner 
Cc: John Ogness 
Cc: linux-serial@vger.kernel.org
Cc: Greg Kroah-Hartman 
Cc: Jiri Slaby 
Reviewed-by: John Ogness 
Link: https://lore.kernel.org/r/20230927044128.4748-1-rdunlap@infradead.org
Signed-off-by: Greg Kroah-Hartman

serial: core: Provide port lock wrappers

2024-02-01T00:17:10+00:00

[ Upstream commit b0af4bcb49464c221ad5f95d40f2b1b252ceedcc ]

When a serial port is used for kernel console output, then all
modifications to the UART registers which are done from other contexts,
e.g. getty, termios, are interference points for the kernel console.

So far this has been ignored and the printk output is based on the
principle of hope. The rework of the console infrastructure which aims to
support threaded and atomic consoles, requires to mark sections which
modify the UART registers as unsafe. This allows the atomic write function
to make informed decisions and eventually to restore operational state. It
also allows to prevent the regular UART code from modifying UART registers
while printk output is in progress.

All modifications of UART registers are guarded by the UART port lock,
which provides an obvious synchronization point with the console
infrastructure.

Provide wrapper functions for spin_[un]lock*(port->lock) invocations so
that the console mechanics can be applied later on at a single place and
does not require to copy the same logic all over the drivers.

Signed-off-by: Thomas Gleixner 
Reviewed-by: Ilpo Järvinen 
Signed-off-by: John Ogness 
Link: https://lore.kernel.org/r/20230914183831.587273-2-john.ogness@linutronix.de
Signed-off-by: Greg Kroah-Hartman 
Stable-dep-of: 9915753037eb ("serial: sc16is7xx: fix unconditional activation of THRI interrupt")
Signed-off-by: Sasha Levin

serial: Deassert Transmit Enable on probe in driver-specific way

2022-09-25T07:28:57+00:00

When a UART port is newly registered, uart_configure_port() seeks to
deassert RS485 Transmit Enable by setting the RTS bit in port->mctrl.
However a number of UART drivers interpret a set RTS bit as *assertion*
instead of deassertion:  Affected drivers include those using
serial8250_em485_config() (except 8250_bcm2835aux.c) and some using
mctrl_gpio (e.g. imx.c).

Since the interpretation of the RTS bit is driver-specific, it is not
suitable as a means to centrally deassert Transmit Enable in the serial
core.  Instead, the serial core must call on drivers to deassert it in
their driver-specific way.  One way to achieve that is to call
->rs485_config().  It implicitly deasserts Transmit Enable.

So amend uart_configure_port() and uart_resume_port() to invoke
uart_rs485_config().  That allows removing calls to uart_rs485_config()
from drivers' ->probe() hooks and declaring the function static.

Skip any invocation of ->set_mctrl() if RS485 is enabled.  RS485 has no
hardware flow control, so the modem control lines are irrelevant and
need not be touched.  When leaving RS485 mode, reset the modem control
lines to the state stored in port->mctrl.  That way, UARTs which are
muxed between RS485 and RS232 transceivers drive the lines correctly
when switched to RS232.  (serial8250_do_startup() historically raises
the OUT1 modem signal because otherwise interrupts are not signaled on
ancient PC UARTs, but I believe that no longer applies to modern,
RS485-capable UARTs and is thus safe to be skipped.)

imx.c modifies port->mctrl whenever Transmit Enable is asserted and
deasserted.  Stop it from doing that so port->mctrl reflects the RS232
line state.

8250_omap.c deasserts Transmit Enable on ->runtime_resume() by calling
->set_mctrl().  Because that is now a no-op in RS485 mode, amend the
function to call serial8250_em485_stop_tx().

fsl_lpuart.c retrieves and applies the RS485 device tree properties
after registering the UART port.  Because applying now happens on
registration in uart_configure_port(), move retrieval of the properties
ahead of uart_add_one_port().

Link: https://lore.kernel.org/all/20220329085050.311408-1-matthias.schiffer@ew.tq-group.com/
Link: https://lore.kernel.org/all/8f538a8903795f22f9acc94a9a31b03c9c4ccacb.camel@ginzinger.com/
Fixes: d3b3404df318 ("serial: Fix incorrect rs485 polarity on uart open")
Cc: stable@vger.kernel.org # v4.14+
Reported-by: Matthias Schiffer 
Reported-by: Roosen Henri 
Tested-by: Matthias Schiffer 
Reviewed-by: Ilpo Järvinen 
Signed-off-by: Lukas Wunner 
Link: https://lore.kernel.org/r/2de36eba3fbe11278d5002e4e501afe0ceaca039.1663863805.git.lukas@wunner.de
Signed-off-by: Greg Kroah-Hartman

Merge 7e2cd21e02b3 ("Merge tag 'tty-6.0-rc7' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/tty") into tty-next

2022-09-25T07:22:13+00:00

We need the tty fixes and api additions in this branch.

Signed-off-by: Greg Kroah-Hartman

serial: 8250: Switch UART port flags to using BIT_ULL

2022-09-22T14:28:47+00:00

Use BIT_ULL rather than encoding bits explicitly where applicable with
UART port flags.  This makes a (__force upf_t) cast redundant, but keep
it for visual consistency with the flags defined in terms of userspace
macros.

Signed-off-by: Maciej W. Rozycki 
Link: https://lore.kernel.org/r/alpine.DEB.2.21.2209210007030.41633@angie.orcam.me.uk
Signed-off-by: Greg Kroah-Hartman

serial: 8250: Let drivers request full 16550A feature probing

2022-09-22T14:28:47+00:00

A SERIAL_8250_16550A_VARIANTS configuration option has been recently
defined that lets one request the 8250 driver not to probe for 16550A
device features so as to reduce the driver's device startup time in
virtual machines.

Some actual hardware devices require these features to have been fully
determined however for their driver to work correctly, so define a flag
to let drivers request full 16550A feature probing on a device-by-device
basis if required regardless of the SERIAL_8250_16550A_VARIANTS option
setting chosen.

Fixes: dc56ecb81a0a ("serial: 8250: Support disabling mdelay-filled probes of 16550A variants")
Cc: stable@vger.kernel.org # v5.6+
Reported-by: Anders Blomdell 
Signed-off-by: Maciej W. Rozycki 
Link: https://lore.kernel.org/r/alpine.DEB.2.21.2209202357520.41633@angie.orcam.me.uk
Signed-off-by: Greg Kroah-Hartman