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: 84a9582fd203 ("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>

We now get errors on system suspend if no_console_suspend is set as
reported by Thomas. The errors started with commit 20a41a62618d ("serial:
8250_omap: Use force_suspend and resume for system suspend").

Let's fix the issue by checking for console_suspend_enabled in the system
suspend and resume path.

Note that with this fix the checks for console_suspend_enabled in
omap8250_runtime_suspend() become useless. We now keep runtime PM usage
count for an attached kernel console starting with commit bedb404e91bb
("serial: 8250_port: Don't use power management for kernel console").

Fixes: 20a41a62618d ("serial: 8250_omap: Use force_suspend and resume for system suspend")
Cc: stable <stable@kernel.org>
Cc: Udit Kumar <u-kumar1@ti.com>
Reported-by: Thomas Richard <thomas.richard@bootlin.com>
Signed-off-by: Tony Lindgren <tony@atomide.com>
Tested-by: Thomas Richard <thomas.richard@bootlin.com>
Reviewed-by: Dhruva Gole <d-gole@ti.com>
Link: https://lore.kernel.org/r/20230926061319.15140-1-tony@atomide.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Commit 44b27aec9d96 ("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 7c7f9bc986e6 ("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: 7c7f9bc986e6 ("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>

In case the leaf driver wants to use IRQ polling (irq = 0) and
IIR register shows that an interrupt happened in the 8250 hardware
the IRQ data can be NULL. In such a case we need to skip the wake
event as we came to this path from the timer interrupt and quite
likely system is already awake.

Without this fix we have got an Oops:

    serial8250: ttyS0 at I/O 0x3f8 (irq = 0, base_baud = 115200) is a 16550A
    ...
    BUG: kernel NULL pointer dereference, address: 0000000000000010
    RIP: 0010:serial8250_handle_irq+0x7c/0x240
    Call Trace:
     ? serial8250_handle_irq+0x7c/0x240
     ? __pfx_serial8250_timeout+0x10/0x10

Fixes: 0ba9e3a13c6a ("serial: 8250: Add missing wakeup event reporting")
Cc: stable <stable@kernel.org>
Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Reviewed-by: Florian Fainelli <florian.fainelli@broadcom.com>
Link: https://lore.kernel.org/r/20230831222555.614426-1-andriy.shevchenko@linux.intel.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Pull tty/serial driver updates from Greg KH:
 "Here is the big set of tty and serial driver changes for 6.6-rc1.

  Lots of cleanups in here this cycle, and some driver updates. Short
  summary is:

   - Jiri's continued work to make the tty code and apis be a bit more
     sane with regards to modern kernel coding style and types

   - cpm_uart driver updates

   - n_gsm updates and fixes

   - meson driver updates

   - sc16is7xx driver updates

   - 8250 driver updates for different hardware types

   - qcom-geni driver fixes

   - tegra serial driver change

   - stm32 driver updates

   - synclink_gt driver cleanups

   - tty structure size reduction

  All of these have been in linux-next this week with no reported
  issues. The last bit of cleanups from Jiri and the tty structure size
  reduction came in last week, a bit late but as they were just style
  changes and size reductions, I figured they should get into this merge
  cycle so that others can work on top of them with no merge conflicts"

* tag 'tty-6.6-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/tty: (199 commits)
  tty: shrink the size of struct tty_struct by 40 bytes
  tty: n_tty: deduplicate copy code in n_tty_receive_buf_real_raw()
  tty: n_tty: extract ECHO_OP processing to a separate function
  tty: n_tty: unify counts to size_t
  tty: n_tty: use u8 for chars and flags
  tty: n_tty: simplify chars_in_buffer()
  tty: n_tty: remove unsigned char casts from character constants
  tty: n_tty: move newline handling to a separate function
  tty: n_tty: move canon handling to a separate function
  tty: n_tty: use MASK() for masking out size bits
  tty: n_tty: make n_tty_data::num_overrun unsigned
  tty: n_tty: use time_is_before_jiffies() in n_tty_receive_overrun()
  tty: n_tty: use 'num' for writes' counts
  tty: n_tty: use output character directly
  tty: n_tty: make flow of n_tty_receive_buf_common() a bool
  Revert "tty: serial: meson: Add a earlycon for the T7 SoC"
  Documentation: devices.txt: Fix minors for ttyCPM*
  Documentation: devices.txt: Remove ttySIOC*
  Documentation: devices.txt: Remove ttyIOC*
  serial: 8250_bcm7271: improve bcm7271 8250 port
  ...

Pull non-MM updates from Andrew Morton:

 - An extensive rework of kexec and crash Kconfig from Eric DeVolder
   ("refactor Kconfig to consolidate KEXEC and CRASH options")

 - kernel.h slimming work from Andy Shevchenko ("kernel.h: Split out a
   couple of macros to args.h")

 - gdb feature work from Kuan-Ying Lee ("Add GDB memory helper
   commands")

 - vsprintf inclusion rationalization from Andy Shevchenko
   ("lib/vsprintf: Rework header inclusions")

 - Switch the handling of kdump from a udev scheme to in-kernel
   handling, by Eric DeVolder ("crash: Kernel handling of CPU and memory
   hot un/plug")

 - Many singleton patches to various parts of the tree

* tag 'mm-nonmm-stable-2023-08-28-22-48' of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm: (81 commits)
  document while_each_thread(), change first_tid() to use for_each_thread()
  drivers/char/mem.c: shrink character device's devlist[] array
  x86/crash: optimize CPU changes
  crash: change crash_prepare_elf64_headers() to for_each_possible_cpu()
  crash: hotplug support for kexec_load()
  x86/crash: add x86 crash hotplug support
  crash: memory and CPU hotplug sysfs attributes
  kexec: exclude elfcorehdr from the segment digest
  crash: add generic infrastructure for crash hotplug support
  crash: move a few code bits to setup support of crash hotplug
  kstrtox: consistently use _tolower()
  kill do_each_thread()
  nilfs2: fix WARNING in mark_buffer_dirty due to discarded buffer reuse
  scripts/bloat-o-meter: count weak symbol sizes
  treewide: drop CONFIG_EMBEDDED
  lockdep: fix static memory detection even more
  lib/vsprintf: declare no_hash_pointers in sprintf.h
  lib/vsprintf: split out sprintf() and friends
  kernel/fork: stop playing lockless games for exe_file replacement
  adfs: delete unused "union adfs_dirtail" definition
  ...

This reverts commit 6a4197f9763325043abf7690a21124a9facbf52e

New SoC will use ttyS0 instead of ttyAML, so T7 SoC doesn't need a
OF_EARLYCON_DECLARE.

Fixes: 6a4197f97633 ("tty: serial: meson: Add a earlycon for the T7 SoC")
Signed-off-by: Lucas Tanure <tanure@linux.com>
Link: https://lore.kernel.org/r/20230827082944.5100-1-tanure@linux.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

The 8250 BCM7271 UART is not a direct match to PORT_16550A and other
generic ports do not match its hardware capabilities. PORT_ALTR matches
the rx trigger levels, but its vendor configurations are not compatible.
Unfortunately this means we need to create another port to fully capture
the hardware capabilities of the BCM7271 UART.

To alleviate some latency pressures, we default the rx trigger level to 8.

Signed-off-by: Justin Chen <justin.chen@broadcom.com>
Reviewed-by: Florian Fainelli <florian.fainelli@broadcom.com>
Acked-by: Doug Berger <opendmb@gmail.com>
Reviewed-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Link: https://lore.kernel.org/r/1692643978-16570-1-git-send-email-justin.chen@broadcom.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Retrieve rs485 devicetree properties on registration of sc16is7xx ports in
case they are attached to an rs485 transceiver.

Signed-off-by: Hugo Villeneuve <hvilleneuve@dimonoff.com>
Reviewed-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>
Reviewed-by: Lech Perczak <lech.perczak@camlingroup.com>
Tested-by: Lech Perczak <lech.perczak@camlingroup.com>
Link: https://lore.kernel.org/r/20230807214556.540627-7-hugo@hugovil.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

When configuring a pin as an output pin with a value of logic 0, we
end up as having a value of logic 1 on the output pin. Setting a
logic 0 a second time (or more) after that will correctly output a
logic 0 on the output pin.

By default, all GPIO pins are configured as inputs. When we enter
sc16is7xx_gpio_direction_output() for the first time, we first set the
desired value in IOSTATE, and then we configure the pin as an output.
The datasheet states that writing to IOSTATE register will trigger a
transfer of the value to the I/O pin configured as output, so if the
pin is configured as an input, nothing will be transferred.

Therefore, set the direction first in IODIR, and then set the desired
value in IOSTATE.

This is what is done in NXP application note AN10587.

Fixes: dfeae619d781 ("serial: sc16is7xx")
Cc: stable@vger.kernel.org
Signed-off-by: Hugo Villeneuve <hvilleneuve@dimonoff.com>
Reviewed-by: Lech Perczak <lech.perczak@camlingroup.com>
Tested-by: Lech Perczak <lech.perczak@camlingroup.com>
Link: https://lore.kernel.org/r/20230807214556.540627-6-hugo@hugovil.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>