Commit Graph

355 Commits

Author SHA1 Message Date
George Kennedy
e3ad503876 serial: core: check uartclk for zero to avoid divide by zero
commit 6eabce6608 upstream.

Calling ioctl TIOCSSERIAL with an invalid baud_base can
result in uartclk being zero, which will result in a
divide by zero error in uart_get_divisor(). The check for
uartclk being zero in uart_set_info() needs to be done
before other settings are made as subsequent calls to
ioctl TIOCSSERIAL for the same port would be impacted if
the uartclk check was done where uartclk gets set.

Oops: divide error: 0000  PREEMPT SMP KASAN PTI
RIP: 0010:uart_get_divisor (drivers/tty/serial/serial_core.c:580)
Call Trace:
 <TASK>
serial8250_get_divisor (drivers/tty/serial/8250/8250_port.c:2576
    drivers/tty/serial/8250/8250_port.c:2589)
serial8250_do_set_termios (drivers/tty/serial/8250/8250_port.c:502
    drivers/tty/serial/8250/8250_port.c:2741)
serial8250_set_termios (drivers/tty/serial/8250/8250_port.c:2862)
uart_change_line_settings (./include/linux/spinlock.h:376
    ./include/linux/serial_core.h:608 drivers/tty/serial/serial_core.c:222)
uart_port_startup (drivers/tty/serial/serial_core.c:342)
uart_startup (drivers/tty/serial/serial_core.c:368)
uart_set_info (drivers/tty/serial/serial_core.c:1034)
uart_set_info_user (drivers/tty/serial/serial_core.c:1059)
tty_set_serial (drivers/tty/tty_io.c:2637)
tty_ioctl (drivers/tty/tty_io.c:2647 drivers/tty/tty_io.c:2791)
__x64_sys_ioctl (fs/ioctl.c:52 fs/ioctl.c:907
    fs/ioctl.c:893 fs/ioctl.c:893)
do_syscall_64 (arch/x86/entry/common.c:52
    (discriminator 1) arch/x86/entry/common.c:83 (discriminator 1))
entry_SYSCALL_64_after_hwframe (arch/x86/entry/entry_64.S:130)

Reported-by: syzkaller <syzkaller@googlegroups.com>
Cc: stable@vger.kernel.org
Signed-off-by: George Kennedy <george.kennedy@oracle.com>
Rule: add
Link: https://lore.kernel.org/stable/1721148848-9784-1-git-send-email-george.kennedy%40oracle.com
Link: https://lore.kernel.org/r/1721219078-3209-1-git-send-email-george.kennedy@oracle.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2024-08-14 13:58:57 +02:00
Tony Lindgren
83290f9f07 serial: core: Fix missing shutdown and startup for serial base port
commit 1aa4ad4eb6 upstream.

We are seeing start_tx being called after port shutdown as noted by Jiri.
This happens because we are missing the startup and shutdown related
functions for the serial base port.

Let's fix the issue by adding startup and shutdown functions for the
serial base port to block tx flushing for the serial base port when the
port is not in use.

Fixes: 84a9582fd2 ("serial: core: Start managing serial controllers to enable runtime PM")
Cc: stable <stable@kernel.org>
Reported-by: Jiri Slaby <jirislaby@kernel.org>
Signed-off-by: Tony Lindgren <tony@atomide.com>
Link: https://lore.kernel.org/r/20240411055848.38190-1-tony@atomide.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2024-04-27 17:11:39 +02:00
Andy Shevchenko
7ae7104d54 serial: core: Clearing the circular buffer before NULLifying it
commit 9cf7ea2eeb upstream.

The circular buffer is NULLified in uart_tty_port_shutdown()
under the spin lock. However, the PM or other timer based callbacks
may still trigger after this event without knowning that buffer pointer
is not valid. Since the serial code is a bit inconsistent in checking
the buffer state (some rely on the head-tail positions, some on the
buffer pointer), it's better to have both aligned, i.e. buffer pointer
to be NULL and head-tail possitions to be the same, meaning it's empty.
This will prevent asynchronous calls to dereference NULL pointer as
reported recently in 8250 case:

  BUG: kernel NULL pointer dereference, address: 00000cf5
  Workqueue: pm pm_runtime_work
  EIP: serial8250_tx_chars (drivers/tty/serial/8250/8250_port.c:1809)
  ...
  ? serial8250_tx_chars (drivers/tty/serial/8250/8250_port.c:1809)
  __start_tx (drivers/tty/serial/8250/8250_port.c:1551)
  serial8250_start_tx (drivers/tty/serial/8250/8250_port.c:1654)
  serial_port_runtime_suspend (include/linux/serial_core.h:667 drivers/tty/serial/serial_port.c:63)
  __rpm_callback (drivers/base/power/runtime.c:393)
  ? serial_port_remove (drivers/tty/serial/serial_port.c:50)
  rpm_suspend (drivers/base/power/runtime.c:447)

The proposed change will prevent ->start_tx() to be called during
suspend on shut down port.

Fixes: 43066e3222 ("serial: port: Don't suspend if the port is still busy")
Cc: stable <stable@kernel.org>
Reported-by: kernel test robot <oliver.sang@intel.com>
Closes: https://lore.kernel.org/oe-lkp/202404031607.2e92eebe-lkp@intel.com
Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Link: https://lore.kernel.org/r/20240404150034.41648-1-andriy.shevchenko@linux.intel.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2024-04-27 17:11:39 +02:00
Peter Collingbourne
4cc3e2ed67 serial: Lock console when calling into driver before registration
[ Upstream commit 801410b26a ]

During the handoff from earlycon to the real console driver, we have
two separate drivers operating on the same device concurrently. In the
case of the 8250 driver these concurrent accesses cause problems due
to the driver's use of banked registers, controlled by LCR.DLAB. It is
possible for the setup(), config_port(), pm() and set_mctrl() callbacks
to set DLAB, which can cause the earlycon code that intends to access
TX to instead access DLL, leading to missed output and corruption on
the serial line due to unintended modifications to the baud rate.

In particular, for setup() we have:

univ8250_console_setup()
-> serial8250_console_setup()
-> uart_set_options()
-> serial8250_set_termios()
-> serial8250_do_set_termios()
-> serial8250_do_set_divisor()

For config_port() we have:

serial8250_config_port()
-> autoconfig()

For pm() we have:

serial8250_pm()
-> serial8250_do_pm()
-> serial8250_set_sleep()

For set_mctrl() we have (for some devices):

serial8250_set_mctrl()
-> omap8250_set_mctrl()
-> __omap8250_set_mctrl()

To avoid such problems, let's make it so that the console is locked
during pre-registration calls to these callbacks, which will prevent
the earlycon driver from running concurrently.

Remove the partial solution to this problem in the 8250 driver
that locked the console only during autoconfig_irq(), as this would
result in a deadlock with the new approach. The console continues
to be locked during autoconfig_irq() because it can only be called
through uart_configure_port().

Although this patch introduces more locking than strictly necessary
(and in particular it also locks during the call to rs485_config()
which is not affected by this issue as far as I can tell), it follows
the principle that it is the responsibility of the generic console
code to manage the earlycon handoff by ensuring that earlycon and real
console driver code cannot run concurrently, and not the individual
drivers.

Signed-off-by: Peter Collingbourne <pcc@google.com>
Reviewed-by: John Ogness <john.ogness@linutronix.de>
Link: https://linux-review.googlesource.com/id/I7cf8124dcebf8618e6b2ee543fa5b25532de55d8
Fixes: 1da177e4c3 ("Linux-2.6.12-rc2")
Cc: stable@vger.kernel.org
Link: https://lore.kernel.org/r/20240304214350.501253-1-pcc@google.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
2024-04-03 15:28:26 +02:00
Lino Sanfilippo
90b8cbd90a serial: Do not hold the port lock when setting rx-during-tx GPIO
commit 07c30ea586 upstream.

Both the imx and stm32 driver set the rx-during-tx GPIO in rs485_config().
Since this function is called with the port lock held, this can be a
problem in case that setting the GPIO line can sleep (e.g. if a GPIO
expander is used which is connected via SPI or I2C).

Avoid this issue by moving the GPIO setting outside of the port lock into
the serial core and thus making it a generic feature.

Also with commit c54d485436 ("serial: stm32: Add support for rs485
RX_DURING_TX output GPIO") the SER_RS485_RX_DURING_TX flag is only set if a
rx-during-tx GPIO is _not_ available, which is wrong. Fix this, too.

Furthermore reset old GPIO settings in case that changing the RS485
configuration failed.

Fixes: c54d485436 ("serial: stm32: Add support for rs485 RX_DURING_TX output GPIO")
Fixes: ca530cfa96 ("serial: imx: Add support for RS485 RX_DURING_TX output GPIO")
Cc: Shawn Guo <shawnguo@kernel.org>
Cc: Sascha Hauer <s.hauer@pengutronix.de>
Cc:  <stable@vger.kernel.org>
Signed-off-by: Lino Sanfilippo <l.sanfilippo@kunbus.com>
Link: https://lore.kernel.org/r/20240103061818.564-2-l.sanfilippo@kunbus.com
Signed-off-by: Lino Sanfilippo <l.sanfilippo@kunbus.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2024-01-31 16:18:58 -08:00
Lino Sanfilippo
9744575e69 serial: core: set missing supported flag for RX during TX GPIO
[ Upstream commit 1a33e33ca0 ]

If the RS485 feature RX-during-TX is supported by means of a GPIO set the
according supported flag. Otherwise setting this feature from userspace may
not be possible, since in uart_sanitize_serial_rs485() the passed RS485
configuration is matched against the supported features and unsupported
settings are thereby removed and thus take no effect.

Cc:  <stable@vger.kernel.org>
Fixes: 163f080eb7 ("serial: core: Add option to output RS485 RX_DURING_TX state via GPIO")
Reviewed-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>
Signed-off-by: Lino Sanfilippo <l.sanfilippo@kunbus.com>
Link: https://lore.kernel.org/r/20240103061818.564-3-l.sanfilippo@kunbus.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
2024-01-31 16:18:47 -08:00
Andy Shevchenko
28c85cd0a6 serial: core: Simplify uart_get_rs485_mode()
[ Upstream commit 7cda0b9eb6 ]

Simplify uart_get_rs485_mode() by using temporary variable for
the GPIO descriptor. With that, use proper type for the flags
of the GPIO descriptor.

Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Link: https://lore.kernel.org/r/20231003142346.3072929-1-andriy.shevchenko@linux.intel.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Stable-dep-of: 1a33e33ca0 ("serial: core: set missing supported flag for RX during TX GPIO")
Signed-off-by: Sasha Levin <sashal@kernel.org>
2024-01-31 16:18:47 -08:00
Lino Sanfilippo
67043c0a6e serial: core, imx: do not set RS485 enabled if it is not supported
commit 74eab89b26 upstream.

If the imx driver cannot support RS485 it nullifies the ports
rs485_supported structure. But it still calls uart_get_rs485_mode() which
may set the RS485_ENABLED flag nevertheless.

This may lead to an attempt to configure RS485 even if it is not supported
when the flag is evaluated in uart_configure_port() at port startup.

Avoid this by bailing out of uart_get_rs485_mode() if the RS485_ENABLED
flag is not supported by the caller.

With this fix a check for RTS availability is now obsolete in the imx
driver, since it can not evaluate to true any more. So remove this check.

Furthermore the explicit nullifcation of rs485_supported is not needed,
since the memory has already been set to zeros at allocation. So remove
this, too.

Fixes: 00d7a00e2a ("serial: imx: Fill in rs485_supported")
Cc: Shawn Guo <shawnguo@kernel.org>
Cc: Sascha Hauer <s.hauer@pengutronix.de>
Cc:  <stable@vger.kernel.org>
Suggested-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
Signed-off-by: Lino Sanfilippo <l.sanfilippo@kunbus.com>
Reviewed-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>
Link: https://lore.kernel.org/r/20240103061818.564-6-l.sanfilippo@kunbus.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2024-01-25 15:35:43 -08:00
Lino Sanfilippo
9a965fba11 serial: core: make sure RS485 cannot be enabled when it is not supported
commit c73986913f upstream.

Some uart drivers specify a rs485_config() function and then decide later
to disable RS485 support for some reason (e.g. imx and ar933).

In these cases userspace may be able to activate RS485 via TIOCSRS485
nevertheless, since in uart_set_rs485_config() an existing rs485_config()
function indicates that RS485 is supported.

Make sure that this is not longer possible by checking the uarts
rs485_supported.flags instead and bailing out if SER_RS485_ENABLED is not
set.

Furthermore instead of returning an empty structure return -ENOTTY if the
RS485 configuration is requested via TIOCGRS485 but RS485 is not supported.
This has a small impact on userspace visibility but it is consistent with
the -ENOTTY error for TIOCGRS485.

Fixes: e849145e1f ("serial: ar933x: Fill in rs485_supported")
Fixes: 55e18c6b6d ("serial: imx: Remove serial_rs485 sanitization")
Cc: Shawn Guo <shawnguo@kernel.org>
Cc: Sascha Hauer <s.hauer@pengutronix.de>
Cc:  <stable@vger.kernel.org>
Reviewed-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>
Signed-off-by: Lino Sanfilippo <l.sanfilippo@kunbus.com>
Link: https://lore.kernel.org/r/20240103061818.564-5-l.sanfilippo@kunbus.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2024-01-25 15:35:43 -08:00
Lino Sanfilippo
cd1508c80d serial: core: fix sanitizing check for RTS settings
commit 4afeced55b upstream.

Among other things uart_sanitize_serial_rs485() tests the sanity of the RTS
settings in a RS485 configuration that has been passed by userspace.
If RTS-on-send and RTS-after-send are both set or unset the configuration
is adjusted and RTS-after-send is disabled and RTS-on-send enabled.

This however makes only sense if both RTS modes are actually supported by
the driver.

With commit be2e2cb1d2 ("serial: Sanitize rs485_struct") the code does
take the driver support into account but only checks if one of both RTS
modes are supported. This may lead to the errorneous result of RTS-on-send
being set even if only RTS-after-send is supported.

Fix this by changing the implemented logic: First clear all unsupported
flags in the RS485 configuration, then adjust an invalid RTS setting by
taking into account which RTS mode is supported.

Cc:  <stable@vger.kernel.org>
Fixes: be2e2cb1d2 ("serial: Sanitize rs485_struct")
Reviewed-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>
Signed-off-by: Lino Sanfilippo <l.sanfilippo@kunbus.com>
Link: https://lore.kernel.org/r/20240103061818.564-4-l.sanfilippo@kunbus.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2024-01-25 15:35:43 -08:00
Tony Lindgren
f112530109 serial: core: Fix runtime PM handling for pending tx
commit 6f699743ae upstream.

Richard reported that a serial port may end up sometimes with tx data
pending in the buffer for long periods of time.

Turns out we bail out early on any errors from pm_runtime_get(),
including -EINPROGRESS. To fix the issue, we need to ignore -EINPROGRESS
as we only care about the runtime PM usage count at this point. We check
for an active runtime PM state later on for tx.

Fixes: 84a9582fd2 ("serial: core: Start managing serial controllers to enable runtime PM")
Cc: stable <stable@kernel.org>
Reported-by: Richard Purdie <richard.purdie@linuxfoundation.org>
Cc: Bruce Ashfield <bruce.ashfield@gmail.com>
Cc: Mikko Rapeli <mikko.rapeli@linaro.org>
Cc: Paul Gortmaker <paul.gortmaker@windriver.com>
Cc: Randy MacLeod <randy.macleod@windriver.com>
Signed-off-by: Tony Lindgren <tony@atomide.com>
Tested-by: Richard Purdie <richard.purdie@linuxfoundation.org>
Link: https://lore.kernel.org/r/20231023074856.61896-1-tony@atomide.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2023-11-08 11:56:24 +01:00
Tony Lindgren
81a61051e0 serial: core: Fix checks for tx runtime PM state
Maximilian reported that surface_serial_hub serdev tx does not work during
system suspend. During system suspend, runtime PM gets disabled in
__device_suspend_late(), and tx is unable to wake-up the serial core port
device that we use to check if tx is safe to start. Johan summarized the
regression noting that serdev tx no longer always works as earlier when the
serdev device is runtime PM active.

The serdev device and the serial core controller devices are siblings of
the serial port hardware device. The runtime PM usage count from serdev
device does not propagate to the serial core device siblings, it only
propagates to the parent.

In addition to the tx issue for suspend, testing for the serial core port
device can cause an unnecessary delay in enabling tx while waiting for the
serial core port device to wake-up. The serial core port device wake-up is
only needed to flush pending tx when the serial port hardware device was
in runtime PM suspended state.

To fix the regression, we need to check the runtime PM state of the parent
serial port hardware device for tx instead of the serial core port device.

As the serial port device drivers may or may not implement runtime PM, we
need to also add a check for pm_runtime_enabled().

Reported-by: Maximilian Luz <luzmaximilian@gmail.com>
Cc: stable <stable@kernel.org>
Fixes: 84a9582fd2 ("serial: core: Start managing serial controllers to enable runtime PM")
Signed-off-by: Tony Lindgren <tony@atomide.com>
Tested-by: Maximilian Luz <luzmaximilian@gmail.com>
Reviewed-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Link: https://lore.kernel.org/r/20231005075644.25936-1-tony@atomide.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2023-10-07 11:23:47 +02:00
Lukas Wunner
8679328eb8 serial: Reduce spinlocked portion of uart_rs485_config()
Commit 44b27aec9d ("serial: core, 8250: set RS485 termination GPIO in
serial core") enabled support for RS485 termination GPIOs behind i2c
expanders by setting the GPIO outside of the critical section protected
by the port spinlock.  Access to the i2c expander may sleep, which
caused a splat with the port spinlock held.

Commit 7c7f9bc986 ("serial: Deassert Transmit Enable on probe in
driver-specific way") erroneously regressed that by spinlocking the
GPIO manipulation again.

Fix by moving uart_rs485_config() (the function manipulating the GPIO)
outside of the spinlocked section and acquiring the spinlock inside of
uart_rs485_config() for the invocation of ->rs485_config() only.

This gets us one step closer to pushing the spinlock down into the
->rs485_config() callbacks which actually need it.  (Some callbacks
do not want to be spinlocked because they perform sleepable register
accesses, see e.g. sc16is7xx_config_rs485().)

Stack trace for posterity:

 Voluntary context switch within RCU read-side critical section!
 WARNING: CPU: 0 PID: 56 at kernel/rcu/tree_plugin.h:318 rcu_note_context_switch
 Call trace:
 rcu_note_context_switch
 __schedule
 schedule
 schedule_timeout
 wait_for_completion_timeout
 bcm2835_i2c_xfer
 __i2c_transfer
 i2c_transfer
 i2c_transfer_buffer_flags
 regmap_i2c_write
 _regmap_raw_write_impl
 _regmap_bus_raw_write
 _regmap_write
 _regmap_update_bits
 regmap_update_bits_base
 pca953x_gpio_set_value
 gpiod_set_raw_value_commit
 gpiod_set_value_nocheck
 gpiod_set_value_cansleep
 uart_rs485_config
 uart_add_one_port
 pl011_register_port
 pl011_probe

Fixes: 7c7f9bc986 ("serial: Deassert Transmit Enable on probe in driver-specific way")
Suggested-by: Lino Sanfilippo <LinoSanfilippo@gmx.de>
Signed-off-by: Lukas Wunner <lukas@wunner.de>
Cc: stable@vger.kernel.org # v6.1+
Link: https://lore.kernel.org/r/f3a35967c28b32f3c6432d0aa5936e6a9908282d.1695307688.git.lukas@wunner.de
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2023-10-03 15:01:18 +02:00
Jiri Slaby (SUSE)
95713967ba tty: make tty_operations::write()'s count size_t
Unify with the rest of the code. Use size_t for counts and ssize_t for
retval.

Signed-off-by: "Jiri Slaby (SUSE)" <jirislaby@kernel.org>
Link: https://lore.kernel.org/r/20230810091510.13006-30-jirislaby@kernel.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2023-08-11 21:12:46 +02:00
Jiri Slaby (SUSE)
dcaafbe6ee tty: propagate u8 data to tty_operations::put_char()
Data are now typed as u8. Propagate this change to
tty_operations::put_char().

Signed-off-by: "Jiri Slaby (SUSE)" <jirislaby@kernel.org>
Cc: Geert Uytterhoeven <geert@linux-m68k.org>
Cc: Heiko Carstens <hca@linux.ibm.com>
Cc: Vasily Gorbik <gor@linux.ibm.com>
Cc: Alexander Gordeev <agordeev@linux.ibm.com>
Cc: Christian Borntraeger <borntraeger@linux.ibm.com>
Cc: Sven Schnelle <svens@linux.ibm.com>
Cc: Karsten Keil <isdn@linux-pingi.de>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Jiri Slaby <jirislaby@kernel.org>
Cc: Shawn Guo <shawnguo@kernel.org>
Cc: Sascha Hauer <s.hauer@pengutronix.de>
Cc: Pengutronix Kernel Team <kernel@pengutronix.de>
Cc: Fabio Estevam <festevam@gmail.com>
Cc: NXP Linux Team <linux-imx@nxp.com>
Cc: Mathias Nyman <mathias.nyman@intel.com>
Link: https://lore.kernel.org/r/20230810091510.13006-29-jirislaby@kernel.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2023-08-11 21:12:46 +02:00
Jiri Slaby (SUSE)
69851e4ab8 tty: propagate u8 data to tty_operations::write()
Data are now typed as u8. Propagate this change to
tty_operations::write().

Signed-off-by: "Jiri Slaby (SUSE)" <jirislaby@kernel.org>
Cc: Richard Henderson <richard.henderson@linaro.org>
Cc: Ivan Kokshaysky <ink@jurassic.park.msu.ru>
Cc: Matt Turner <mattst88@gmail.com>
Cc: Geert Uytterhoeven <geert@linux-m68k.org>
Cc: Richard Weinberger <richard@nod.at>
Cc: Anton Ivanov <anton.ivanov@cambridgegreys.com>
Cc: Johannes Berg <johannes@sipsolutions.net>
Cc: Chris Zankel <chris@zankel.net>
Cc: Max Filippov <jcmvbkbc@gmail.com>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Vaibhav Gupta <vaibhavgupta40@gmail.com>
Cc: Jens Taprogge <jens.taprogge@taprogge.org>
Cc: Karsten Keil <isdn@linux-pingi.de>
Cc: Scott Branden <scott.branden@broadcom.com>
Cc: Ulf Hansson <ulf.hansson@linaro.org>
Cc: "David S. Miller" <davem@davemloft.net>
Cc: Eric Dumazet <edumazet@google.com>
Cc: Jakub Kicinski <kuba@kernel.org>
Cc: Paolo Abeni <pabeni@redhat.com>
Cc: Heiko Carstens <hca@linux.ibm.com>
Cc: Vasily Gorbik <gor@linux.ibm.com>
Cc: Alexander Gordeev <agordeev@linux.ibm.com>
Cc: Christian Borntraeger <borntraeger@linux.ibm.com>
Cc: Sven Schnelle <svens@linux.ibm.com>
Cc: David Lin <dtwlin@gmail.com>
Cc: Johan Hovold <johan@kernel.org>
Cc: Alex Elder <elder@kernel.org>
Cc: Laurentiu Tudor <laurentiu.tudor@nxp.com>
Cc: Jiri Kosina <jikos@kernel.org>
Cc: David Sterba <dsterba@suse.com>
Cc: Shawn Guo <shawnguo@kernel.org>
Cc: Sascha Hauer <s.hauer@pengutronix.de>
Cc: Pengutronix Kernel Team <kernel@pengutronix.de>
Cc: Fabio Estevam <festevam@gmail.com>
Cc: NXP Linux Team <linux-imx@nxp.com>
Cc: Arnaud Pouliquen <arnaud.pouliquen@foss.st.com>
Cc: Oliver Neukum <oneukum@suse.com>
Cc: Mathias Nyman <mathias.nyman@intel.com>
Cc: Marcel Holtmann <marcel@holtmann.org>
Cc: Johan Hedberg <johan.hedberg@gmail.com>
Cc: Luiz Augusto von Dentz <luiz.dentz@gmail.com>
Link: https://lore.kernel.org/r/20230810091510.13006-28-jirislaby@kernel.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2023-08-11 21:12:46 +02:00
Jiri Slaby
602c802114 serial: move WARN_ON() in uart_write() to the condition
uart code currently does the following in uart_write() and
uart_flush_buffer():
  if (cond) {
    WARN_ON(1);
    return;
  }

It can be rewritten to more obvious and more readable:
  if (WARN_ON(cond))
    return;

Do so.

Signed-off-by: Jiri Slaby (SUSE) <jirislaby@kernel.org>
Link: https://lore.kernel.org/r/20230731080244.2698-2-jirislaby@kernel.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2023-07-31 17:16:04 +02:00
Jiri Slaby
1225541cfd serial: pass state to __uart_start() directly
__uart_start() does not need a tty struct. It works only with
uart_state. So pass the latter directly.

Signed-off-by: Jiri Slaby (SUSE) <jirislaby@kernel.org>
Link: https://lore.kernel.org/r/20230712081811.29004-8-jirislaby@kernel.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2023-07-25 19:21:03 +02:00
Jiri Slaby
df007fa025 serial: make uart_insert_char() accept u8s
Both the character and flag are 8-bit values. So switch from unsigned
ints to u8s. The drivers will be cleaned up in the next round.

Signed-off-by: Jiri Slaby (SUSE) <jirislaby@kernel.org>
Link: https://lore.kernel.org/r/20230712081811.29004-7-jirislaby@kernel.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2023-07-25 19:21:03 +02:00
Jiri Slaby
12ae2359eb serial: convert uart sysrq handling to u8
Propagate u8 from the sysrq code further up to serial's
uart_handle_sysrq_char() and friends.

Signed-off-by: Jiri Slaby (SUSE) <jirislaby@kernel.org>
Link: https://lore.kernel.org/r/20230712081811.29004-6-jirislaby@kernel.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2023-07-25 19:21:03 +02:00
Tony Lindgren
49c80922ff serial: core: Fix error handling for serial_core_ctrl_device_add()
Checking for NULL is incorrect as serial_base_ctrl_add() uses ERR_PTR().

Let's also pass any returned error along, there's no reason to translate
all errors to -ENODEV.

Fixes: 84a9582fd2 ("serial: core: Start managing serial controllers to enable runtime PM")
Signed-off-by: Tony Lindgren <tony@atomide.com>
Reviewed-by: Jiri Slaby <jirislaby@kernel.org>
Link: https://lore.kernel.org/r/20230602070007.59268-1-tony@atomide.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2023-06-02 08:30:55 +01:00
Steven Price
d0a396083e serial: core: Don't drop port_mutex in serial_core_remove_one_port
Commit 84a9582fd2 ("serial: core: Start managing serial controllers to
enable runtime PM") required the caller to hold port_mutex rather than
taking it locally. However the mutex_unlock() call wasn't removed
causing the mutex to be dropped unexpectly. Remove the call to
mutex_unlock() (and fix up the early return) to restore correct
behaviour.

Fixes: 84a9582fd2 ("serial: core: Start managing serial controllers to enable runtime PM")
Signed-off-by: Steven Price <steven.price@arm.com>
Reviewed-by: Tony Lindgren <tony@atomide.com>
Link: https://lore.kernel.org/r/20230601105548.29965-1-steven.price@arm.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2023-06-01 14:04:01 +01:00
Tony Lindgren
84a9582fd2 serial: core: Start managing serial controllers to enable runtime PM
We want to enable runtime PM for serial port device drivers in a generic
way. To do this, we want to have the serial core layer manage the
registered physical serial controller devices.

To manage serial controllers, let's set up a struct bus and struct device
for the serial core controller as suggested by Greg and Jiri. The serial
core controller devices are children of the physical serial port device.
The serial core controller device is needed to support multiple different
kind of ports connected to single physical serial port device.

Let's also set up a struct device for the serial core port. The serial
core port instances are children of the serial core controller device.

With the serial core port device we can now flush pending TX on the
runtime PM resume as suggested by Johan.

Suggested-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Suggested-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Suggested-by: Jiri Slaby <jirislaby@kernel.org>
Suggested-by: Johan Hovold <johan@kernel.org>
Signed-off-by: Tony Lindgren <tony@atomide.com>
Reviewed-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Link: https://lore.kernel.org/r/20230525113034.46880-1-tony@atomide.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2023-05-31 10:46:59 +01:00
John Ogness
51e45fba14 serial: core: lock port for start_rx() in uart_resume_port()
The only user of the start_rx() callback (qcom_geni) directly calls
its own stop_rx() callback. Since stop_rx() requires that the
port->lock is taken and interrupts are disabled, the start_rx()
callback has the same requirement.

Fixes: cfab87c2c2 ("serial: core: Introduce callback for start_rx and do stop_rx in suspend only if this callback implementation is present.")
Signed-off-by: John Ogness <john.ogness@linutronix.de>
Reviewed-by: Douglas Anderson <dianders@chromium.org>
Link: https://lore.kernel.org/r/20230525093159.223817-5-john.ogness@linutronix.de
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2023-05-30 11:45:42 +01:00
John Ogness
abcb0cf1f5 serial: core: lock port for stop_rx() in uart_suspend_port()
The uarts_ops stop_rx() callback expects that the port->lock is
taken and interrupts are disabled.

Fixes: c9d2325cdb ("serial: core: Do stop_rx in suspend path for console if console_suspend is disabled")
Signed-off-by: John Ogness <john.ogness@linutronix.de>
Reviewed-by: Douglas Anderson <dianders@chromium.org>
Link: https://lore.kernel.org/r/20230525093159.223817-3-john.ogness@linutronix.de
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2023-05-30 11:45:42 +01:00
Uwe Kleine-König
d5b3d02d0b serial: Make uart_remove_one_port() return void
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 <u.kleine-koenig@pengutronix.de>
Link: https://lore.kernel.org/r/20230512173810.131447-3-u.kleine-koenig@pengutronix.de
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2023-05-13 19:48:16 +09:00
Tony Lindgren
63f4c34561 serial: core: Disable uart_start() on uart_remove_one_port()
While rebinding a uart device in a loop I noticed we may see a tx related
race on uart_remove_one_port():

uart_write from n_tty_write
n_tty_write from file_tty_write.constprop.0
file_tty_write.constprop.0 from vfs_write
vfs_write from ksys_write
ksys_write from ret_fast_syscall

Let's disallow tx on port->UPF_DEAD. This flag gets set before we start
tearing down the port in uart_remove_one_port().

Signed-off-by: Tony Lindgren <tony@atomide.com>
Link: https://lore.kernel.org/r/20230419115423.59957-1-tony@atomide.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2023-04-20 13:43:44 +02:00
Johan Hovold
9e4f2a8004 serial: fix TIOCSRS485 locking
The RS485 multipoint addressing support for some reason added a new
ADDRB termios cflag which is (only!) updated from one of the RS485
ioctls.

Make sure to take the termios rw semaphore for the right ioctl (i.e.
set, not get).

Fixes: ae50bb2752 ("serial: take termios_rwsem for ->rs485_config() & pass termios as param")
Cc: stable@vger.kernel.org	# 6.0
Cc: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>
Reviewed-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>
Signed-off-by: Johan Hovold <johan@kernel.org>
Link: https://lore.kernel.org/r/20230412124811.11217-1-johan@kernel.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2023-04-20 13:42:24 +02:00
Douglas Anderson
5e227ef2aa serial: uart_poll_init() should power on the UART
On Qualcomm devices which use the "geni" serial driver, kdb/kgdb won't
be very happy if you use it but the resources of the port haven't been
powered on. Today kdb/kgdb rely on someone else powering the port
on. This could be the normal kernel console or an agetty running.
Let's fix this to explicitly power things on when setting up a polling
driver.

Signed-off-by: Douglas Anderson <dianders@chromium.org>
Link: https://lore.kernel.org/r/20230316132027.RESEND.1.I106c39498d8094c6f5e7ada42c7db17aa5c64e48@changeid
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2023-03-29 10:51:52 +02:00
Ilpo Järvinen
044498cd89 serial: Remove uart_wait_until_sent() forward declaration
Remove unnecessary forward declaration of uart_wait_until_sent().

Signed-off-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>
Link: https://lore.kernel.org/r/20230309080923.11778-9-ilpo.jarvinen@linux.intel.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2023-03-17 15:00:40 +01:00
Ilpo Järvinen
1690ca513d serial: Rename hw_stopped to old_hw_stopped & improve logic
hw_stopped in uart_change_line_settings() stores old hw_stopped, thus
rename it appropriately.

Alter logic to check first if the hw_stopped was changed, and then pick
which function to call if it was because the logic is more obvious that
way.

Signed-off-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>
Link: https://lore.kernel.org/r/20230309080923.11778-8-ilpo.jarvinen@linux.intel.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2023-03-17 15:00:40 +01:00
Ilpo Järvinen
b5def43a7b serial: Make hw_stopped bool
Convert hw_stopped in uart_port to bool because its more appropriate
type for how it is used.

Also convert the local variable in uart_change_line_settings() caching
old hw_stopped to bool.

Signed-off-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>
Link: https://lore.kernel.org/r/20230309080923.11778-7-ilpo.jarvinen@linux.intel.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2023-03-17 15:00:40 +01:00
Ilpo Järvinen
826736a6c7 serial: Rename uart_change_speed() to uart_change_line_settings()
uart_change_speed() changes more than just speed so rename it to more
generic uart_change_line_settings().

Signed-off-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>
Link: https://lore.kernel.org/r/20230309080923.11778-6-ilpo.jarvinen@linux.intel.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2023-03-17 15:00:40 +01:00
Ilpo Järvinen
8e90cf29ae serial: Move uart_change_speed() earlier
Move uart_change_speed() earlier to get rid of its forward declaration.

Signed-off-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>
Link: https://lore.kernel.org/r/20230309080923.11778-5-ilpo.jarvinen@linux.intel.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2023-03-17 15:00:40 +01:00
Ilpo Järvinen
807fccf719 serial: Use B0 instead of implicit zero assumption
Compare against B0 rather than assume B0 equals zero, which is true for
all archs but explicit B0 makes the code more obvious.

Signed-off-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>
Link: https://lore.kernel.org/r/20230309080923.11778-3-ilpo.jarvinen@linux.intel.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2023-03-17 15:00:40 +01:00
Ilpo Järvinen
eff37b5ea3 serial: Use ARRAY_SIZE() with iso7816 reserved array
Instead of a literal, size the for loop iteration based on the actual
array using ARRAY_SIZE().

Signed-off-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>
Link: https://lore.kernel.org/r/20230309080923.11778-2-ilpo.jarvinen@linux.intel.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2023-03-17 15:00:40 +01:00
Greg Kroah-Hartman
7a6aa989f2 Merge 6.2-rc5 into tty-next
We need the serial/tty changes into this branch as well.

Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2023-01-22 12:55:13 +01:00
Ilpo Järvinen
5701cb8bf5 tty: Call ->dtr_rts() parameter active consistently
Convert various parameter names for ->dtr_rts() and related functions
from onoff, on, and raise to active.

Reviewed-by: Jiri Slaby <jirislaby@kernel.org>
Acked-by: Ulf Hansson <ulf.hansson@linaro.org> # For MMC
Signed-off-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>
Link: https://lore.kernel.org/r/20230117090358.4796-12-ilpo.jarvinen@linux.intel.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2023-01-19 16:04:35 +01:00
Ilpo Järvinen
968d64578e serial: Make uart_handle_cts_change() status param bool active
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 <jirislaby@kernel.org>
Signed-off-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>
Link: https://lore.kernel.org/r/20230117090358.4796-10-ilpo.jarvinen@linux.intel.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2023-01-19 16:04:35 +01:00
Ilpo Järvinen
0388a152fc tty/serial: Make ->dcd_change()+uart_handle_dcd_change() status bool active
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 <giometti@enneenne.com>
Reviewed-by: Jiri Slaby <jirislaby@kernel.org>
Signed-off-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>
Link: https://lore.kernel.org/r/20230117090358.4796-9-ilpo.jarvinen@linux.intel.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2023-01-19 16:04:35 +01:00
Ilpo Järvinen
5d42039907 tty: Convert ->dtr_rts() to take bool argument
Convert the raise/on parameter in ->dtr_rts() to bool through the
callchain. The parameter is used like bool. In USB serial, there
remains a few implicit bool -> larger type conversions because some
devices use u8 in their control messages.

In moxa_tiocmget(), dtr variable was reused for line status which
requires int so use a separate variable for status.

Reviewed-by: Jiri Slaby <jirislaby@kernel.org>
Acked-by: Ulf Hansson <ulf.hansson@linaro.org> # For MMC
Signed-off-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>
Link: https://lore.kernel.org/r/20230117090358.4796-8-ilpo.jarvinen@linux.intel.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2023-01-19 16:04:35 +01:00
Ilpo Järvinen
b300fb26c5 tty: Convert ->carrier_raised() and callchains to bool
Return boolean from ->carrier_raised() instead of 0 and 1. Make the
return type change also to tty_port_carrier_raised() that makes the
->carrier_raised() call (+ cd variable in moxa into which its return
value is stored).

Also cleans up a few unnecessary constructs related to this change:

	return xx ? 1 : 0;
	-> return xx;

	if (xx)
		return 1;
	return 0;
	-> return xx;

Reviewed-by: Jiri Slaby <jirislaby@kernel.org>
Acked-by: Ulf Hansson <ulf.hansson@linaro.org> # For MMC
Signed-off-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>
Link: https://lore.kernel.org/r/20230117090358.4796-7-ilpo.jarvinen@linux.intel.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2023-01-19 16:04:35 +01:00
Ilpo Järvinen
dcd794c6ed serial: Convert uart_{,port_}startup() init_hw param to bool
Convert init_hw parameter in uart_startup() and uart_port_startup() to
bool as code treats them like bool.

Reviewed-by: Jiri Slaby <jirislaby@kernel.org>
Signed-off-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>
Link: https://lore.kernel.org/r/20230117090358.4796-6-ilpo.jarvinen@linux.intel.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2023-01-19 16:04:34 +01:00
Ilpo Järvinen
9b5aa54986 tty: Cleanup tty_port_set_active() bool parameter
Make callers pass true/false consistently for bool val.

Reviewed-by: Jiri Slaby <jirislaby@kernel.org>
Signed-off-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>
Link: https://lore.kernel.org/r/20230117090358.4796-4-ilpo.jarvinen@linux.intel.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2023-01-19 16:04:34 +01:00
Ilpo Järvinen
75b20a2ac4 tty: Cleamup tty_port_set_suspended() bool parameter
Make callers pass true/false consistently for bool val.

Reviewed-by: Jiri Slaby <jirislaby@kernel.org>
Signed-off-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>
Link: https://lore.kernel.org/r/20230117090358.4796-3-ilpo.jarvinen@linux.intel.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2023-01-19 16:04:34 +01:00
Ilpo Järvinen
515be7baed tty: Cleanup tty_port_set_initialized() bool parameter
Make callers pass true/false consistently for bool val.

Reviewed-by: Samuel Iglesias Gonsalvez <siglesias@igalia.com>
Reviewed-by: Jiri Slaby <jirislaby@kernel.org>
Signed-off-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>
Link: https://lore.kernel.org/r/20230117090358.4796-2-ilpo.jarvinen@linux.intel.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2023-01-19 16:04:34 +01:00
Christoph Niedermaier
163f080eb7 serial: core: Add option to output RS485 RX_DURING_TX state via GPIO
This patch provides a generic GPIO variable for outputting the state
of RS485 RX_DURING_TX. The GPIO is defined by the devicetree property
"rs485-rx-during-tx-gpios". To use it in a low level serial driver,
the evaluation of this variable must be implemented there accordingly.

Signed-off-by: Christoph Niedermaier <cniedermaier@dh-electronics.com>
Link: https://lore.kernel.org/r/20221202104127.122761-2-cniedermaier@dh-electronics.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2023-01-19 16:01:35 +01:00
John Ogness
3ef5abd9b5 tty: serial: kgdboc: fix mutex locking order for configure_kgdboc()
Several mutexes are taken while setting up console serial ports. In
particular, the tty_port->mutex and @console_mutex are taken:

  serial_pnp_probe
    serial8250_register_8250_port
      uart_add_one_port (locks tty_port->mutex)
        uart_configure_port
          register_console (locks @console_mutex)

In order to synchronize kgdb's tty_find_polling_driver() with
register_console(), commit 6193bc9084 ("tty: serial: kgdboc:
synchronize tty_find_polling_driver() and register_console()") takes
the @console_mutex. However, this leads to the following call chain
(with locking):

  platform_probe
    kgdboc_probe
      configure_kgdboc (locks @console_mutex)
        tty_find_polling_driver
          uart_poll_init (locks tty_port->mutex)
            uart_set_options

This is clearly deadlock potential due to the reverse lock ordering.

Since uart_set_options() requires holding @console_mutex in order to
serialize early initialization of the serial-console lock, take the
@console_mutex in uart_poll_init() instead of configure_kgdboc().

Since configure_kgdboc() was using @console_mutex for safe traversal
of the console list, change it to use the SRCU iterator instead.

Add comments to uart_set_options() kerneldoc mentioning that it
requires holding @console_mutex (aka the console_list_lock).

Fixes: 6193bc9084 ("tty: serial: kgdboc: synchronize tty_find_polling_driver() and register_console()")
Signed-off-by: John Ogness <john.ogness@linutronix.de>
Reviewed-by: Sergey Senozhatsky <senozhatsky@chromium.org>
Reviewed-by: Petr Mladek <pmladek@suse.com>
[pmladek@suse.com: Export console_srcu_read_lock_is_held() to fix build kgdboc as a module.]
Signed-off-by: Petr Mladek <pmladek@suse.com>
Link: https://lore.kernel.org/r/20230112161213.1434854-1-john.ogness@linutronix.de
2023-01-16 16:44:53 +01:00
John Ogness
452b9b2475 serial_core: replace uart_console_enabled() with uart_console_registered()
All users of uart_console_enabled() really want to know if a console
is registered. It is not reliable to check for CON_ENABLED in order
to identify if a console is registered. Use console_is_registered()
instead.

A _locked() variant is provided because uart_set_options() is always
called with the console_list_lock held and must check if a console
is registered in order to synchronize with kgdboc.

Signed-off-by: John Ogness <john.ogness@linutronix.de>
Reviewed-by: Petr Mladek <pmladek@suse.com>
Signed-off-by: Petr Mladek <pmladek@suse.com>
Link: https://lore.kernel.org/r/20221116162152.193147-23-john.ogness@linutronix.de
2022-12-02 11:25:01 +01:00
Lukas Wunner
7c7f9bc986 serial: Deassert Transmit Enable on probe in driver-specific way
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: d3b3404df3 ("serial: Fix incorrect rs485 polarity on uart open")
Cc: stable@vger.kernel.org # v4.14+
Reported-by: Matthias Schiffer <matthias.schiffer@ew.tq-group.com>
Reported-by: Roosen Henri <Henri.Roosen@ginzinger.com>
Tested-by: Matthias Schiffer <matthias.schiffer@ew.tq-group.com>
Reviewed-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>
Signed-off-by: Lukas Wunner <lukas@wunner.de>
Link: https://lore.kernel.org/r/2de36eba3fbe11278d5002e4e501afe0ceaca039.1663863805.git.lukas@wunner.de
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2022-09-25 09:28:57 +02:00