Introduce the UART_CAP_NOTEMT capability. The capability indicates that
the UART doesn't have an interrupt available on TEMT.

In the case where the device does not support it, we calculate the
maximum time it could take for the transmitter to empty the
shift register. When we get in the situation where we get the
THRE interrupt, we check if the TEMT bit is set. If it's not, we start
the a timer and recall __stop_tx() after the delay.

The transmit sequence is a bit modified when the capability is set. The
new timer is used between the last interrupt(THRE) and a potential
stop_tx timer.
Signed-off-by: Giulio Benetti <giulio.benetti@micronovasrl.com>
[moved to use added UART_CAP_TEMT]
Signed-off-by: Heiko Stuebner <heiko.stuebner@theobroma-systems.com>
[moved to use added UART_CAP_NOTEMT, improve timeout]
Signed-off-by: Eric Tremblay <etremblay@distech-controls.com>
[rebased to v5.17, making use of tty_get_frame_size]
Signed-off-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
Link: https://lore.kernel.org/r/20220330104642.229507-2-u.kleine-koenig@pengutronix.deSigned-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

platform_get_resource() may fail and return NULL, so we should
better check it's return value to avoid a NULL pointer dereference.

Fixes: 54da3e38 ("serial: 8250_aspeed_vuart: use UPF_IOREMAP to set up register mapping")
Signed-off-by: Miaoqian Lin <linmq006@gmail.com>
Link: https://lore.kernel.org/r/20220404143842.16960-1-linmq006@gmail.comSigned-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

In uart_set_rs485_config() the serial core already assigns the passed
serial_rs485 struct to the uart port.

So remove the assignment from the drivers rs485_config() function to avoid
redundancy.
Reviewed-by: Claudiu Beznea <claudiu.beznea@microchip.com>
Acked-by: Richard Genoud <richard.genoud@gmail.com>
Signed-off-by: Lino Sanfilippo <LinoSanfilippo@gmx.de>
Link: https://lore.kernel.org/r/20220410104642.32195-10-LinoSanfilippo@gmx.deSigned-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

In uart_set_rs485_config() the serial core already ensures that only one of
both options RTS on send or RTS after send is set. It also assigns the
passed serial_rs485 struct to the uart port.

So remove the check and the assignment from the drivers rs485_config()
function to avoid redundancy.
Signed-off-by: Lino Sanfilippo <LinoSanfilippo@gmx.de>
Link: https://lore.kernel.org/r/20220410104642.32195-9-LinoSanfilippo@gmx.deSigned-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

In uart_set_rs485_config() the serial core already assigns the passed
serial_rs485 struct to the uart port.

So remove the assignment in the drivers rs485_config() function to avoid
reduncancy.
Acked-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
Signed-off-by: Lino Sanfilippo <LinoSanfilippo@gmx.de>
Link: https://lore.kernel.org/r/20220410104642.32195-8-LinoSanfilippo@gmx.deSigned-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

In uart_set_rs485_config() the serial core already nullifies the padding
field of the passed serial_rs485 struct before returning it to userspace.

Doing the same in the drivers rs485_config() function is redundant, so
remove the concerning memset in this function.
Signed-off-by: Lino Sanfilippo <LinoSanfilippo@gmx.de>
Link: https://lore.kernel.org/r/20220410104642.32195-7-LinoSanfilippo@gmx.deSigned-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

In uart_set_rs485_config() the serial core already clamps the RTS delays.
It also assigns the passed serial_rs485 struct to the uart port.

So remove these tasks from the drivers rs485_config() function to avoid
redundancy.
Signed-off-by: Lino Sanfilippo <LinoSanfilippo@gmx.de>
Link: https://lore.kernel.org/r/20220410104642.32195-6-LinoSanfilippo@gmx.deSigned-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

In uart_set_rs485_config() the serial core already ensures that only one of
both options RTS on send or RTS after send is set.

So remove this check from the drivers rs485_config() function to avoid
redundancy.
Signed-off-by: Lino Sanfilippo <LinoSanfilippo@gmx.de>
Link: https://lore.kernel.org/r/20220410104642.32195-5-LinoSanfilippo@gmx.deSigned-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

In uart_set_rs485_config() the serial core already ensures that only one of
both options RTS on send or RTS after send is set. It also assigns the
passed serial_rs485 struct to the uart port.

So remove the check and the assignment from the drivers rs485_config()
function to avoid redundancy.
Signed-off-by: Lino Sanfilippo <LinoSanfilippo@gmx.de>
Link: https://lore.kernel.org/r/20220410104642.32195-4-LinoSanfilippo@gmx.deSigned-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

In uart_set_rs485_config() the serial core already

- ensures that only one of both options RTS on send or RTS after send is
  set

- nullifies the padding field of the passed serial_rs485 struct

- clamps the RTS delays

- assigns the passed serial_rs485 struct to the uart port

So remove these tasks from the code of the drivers rs485_config() function
to avoid redundancy.
Signed-off-by: Lino Sanfilippo <LinoSanfilippo@gmx.de>
Link: https://lore.kernel.org/r/20220410104642.32195-3-LinoSanfilippo@gmx.deSigned-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Several drivers that support setting the RS485 configuration via userspace
implement one or more of the following tasks:

- in case of an invalid RTS configuration (both RTS after send and RTS on
  send set or both unset) fall back to enable RTS on send and disable RTS
  after send

- nullify the padding field of the returned serial_rs485 struct

- copy the configuration into the uart port struct

- limit RTS delays to 100 ms

Move these tasks into the serial core to make them generic and to provide
a consistent behaviour among all drivers.
Signed-off-by: Lino Sanfilippo <LinoSanfilippo@gmx.de>
Link: https://lore.kernel.org/r/20220410104642.32195-2-LinoSanfilippo@gmx.deSigned-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Due to chip process differences, chip designers recommend using baud
rates as close to and larger as possible in order to reduce clock
errors.
Signed-off-by: Yu Tu <yu.tu@amlogic.com>
Reviewed-by: Neil Armstrong <narmstrong@baylibre.com>
Link: https://lore.kernel.org/r/20220407081355.13602-2-yu.tu@amlogic.comSigned-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Similar to I2C controller, move geni based QUP UART controller binding
out from parent schema to an individual binding and let parent refer to
child schema later on. UART binding also stand incomplete right now
similar to I2C, complete it along this process.
Signed-off-by: Kuldeep Singh <singh.kuldeep87k@gmail.com>
Reviewed-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
Link: https://lore.kernel.org/r/20220404182938.29492-4-singh.kuldeep87k@gmail.comSigned-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Provide information in the kernel log as to what configuration option to
enable for PCI UART devices that have been blacklisted in the generic
PCI 8250 UART driver and which have a dedicated driver available to
handle that has been disabled.  The rationale is there is no easy way
for the user to map a specific PCI vendor:device pair to an individual
dedicated driver while the generic driver has this information readily
available and it will likely be confusing that the generic driver does
not register such a port.

This is unlike usual drivers, such as drivers/net/ethernet/3com/3c59x.c
which handles all the hardware family members regardless of differences
between them, and following an existing example where a serio driver
provides suggestions as to the correct configuration options to use:

psmouse serio1: synaptics: The touchpad can support a better bus than the too old PS/2 protocol. Make sure MOUSE_PS2_SYNAPTICS_SMBUS and RMI4_SMB are enabled to get a better touchpad experience.

A message is then printed like:

serial 0000:04:00.3: ignoring port, enable SERIAL_8250_PERICOM to handle

when an affected device is encountered and the generic driver rejects it.
Signed-off-by: Maciej W. Rozycki <macro@orcam.me.uk>
Link: https://lore.kernel.org/r/alpine.DEB.2.21.2203310054120.44113@angie.orcam.me.ukSigned-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

TTYs in ICANON mode have a special case that allows "pushing" a line
without a regular EOL character (like newline), by using EOF (the EOT
character - ASCII 0x4) as a pseudo-EOL. It is silently discarded, so
the reader of the PTS will receive the line *without* EOF or any other
terminating character.

This special case has an edge case: What happens if the readers buffer
is the same size as the line (without EOF)? Will they be able to tell
if the whole line is received, i.e. if the next read() will return more
of the same line or the next line?

There are two possibilities,  that both have (dis)advantages:

1. The next read() returns 0. FreeBSD (13.0) and OSX (10.11) do this.
   Advantage: The reader can interpret this as "the line is over".
   Disadvantage: read() returning 0 means EOF, the reader could also
   interpret it as "there's no more data" and stop reading or even
   close the PT.

2. The next read() returns the next line, the EOF is silently discarded.
   Solaris (or at least OpenIndiana 2021.10) does this, Linux has done
   do this since commit 40d5e090 ("n_tty: Fix EOF push handling");
   this behavior was recently broken by commit 35930307 ("tty:
   n_tty: do not look ahead for EOL character past the end of the buffer").
   Advantage: read() won't return 0 (EOF), reader less likely to be
   confused (and things like `while(read(..)>0)` don't break)
   Disadvantage: The reader can't really know if the read() continues
   the last line (that filled the whole read buffer) or starts a
   new line.

As both options are defensible (and are used by other Unix-likes), it's
best to stick to the "old" behavior since "n_tty: Fix EOF push handling"
of 2013, i.e. silently discard that EOF.

This patch - that I actually got from Linus for testing and only
modified slightly - restores that behavior by skipping an EOF
character if it's the next character after reading is done.

Based on a patch from Linus Torvalds.

Link: https://bugzilla.kernel.org/show_bug.cgi?id=215611
Fixes: 35930307 ("tty: n_tty: do not look ahead for EOL character past the end of the buffer")
Cc: Peter Hurley <peter@hurleysoftware.com>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Jiri Slaby <jirislaby@kernel.org>
Reviewed-and-tested-by: Daniel Gibson <daniel@gibson.sh>
Acked-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Daniel Gibson <daniel@gibson.sh>
Link: https://lore.kernel.org/r/20220329235810.452513-2-daniel@gibson.shSigned-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

This is needed for the Renesas RZ/V2M (r9a09g011) SoC.
Signed-off-by: Phil Edworthy <phil.edworthy@renesas.com>
Reviewed-by: Biju Das <biju.das.jz@bp.renesas.com>
Reviewed-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Link: https://lore.kernel.org/r/20220330154024.112270-6-phil.edworthy@renesas.comSigned-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

The Renesas RZ/V2M (r9a09g011) SoC uses a uart that is compatible with the
EMMA Mobile SoC.
Signed-off-by: Phil Edworthy <phil.edworthy@renesas.com>
Reviewed-by: Biju Das <biju.das.jz@bp.renesas.com>
Link: https://lore.kernel.org/r/20220330154024.112270-3-phil.edworthy@renesas.comAcked-by: Rob Herring <robh@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

The lpuart on i.MX93 is derived from i.MX7ULP with some industrial
enhancements, it uses two compatible strings, so update the
compatible string for i.MX93.
Acked-by: Rob Herring <robh@kernel.org>
Signed-off-by: Peng Fan <peng.fan@nxp.com>
Link: https://lore.kernel.org/r/20220323093659.1722463-1-peng.fan@oss.nxp.comSigned-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

UniPhier UART controller has a reset lines from system controller.
Add "resets" property to fix the following warning.

  uniphier-ld11-global.dtb: serial@54006800: 'resets' does not match any of the regexes: 'pinctrl-[0-9]+'
      From schema: Documentation/devicetree/bindings/serial/socionext,uniphier-uart.yaml
Reviewed-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
Signed-off-by: Kunihiko Hayashi <hayashi.kunihiko@socionext.com>
Link: https://lore.kernel.org/r/1648617338-8600-3-git-send-email-hayashi.kunihiko@socionext.comSigned-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

'maxItems' is preferred for a single entry, not 'minItems'.
Reviewed-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
Signed-off-by: Kunihiko Hayashi <hayashi.kunihiko@socionext.com>
Link: https://lore.kernel.org/r/1648617338-8600-2-git-send-email-hayashi.kunihiko@socionext.comSigned-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Fix the missing clk_disable_unprepare() before return
from owl_uart_probe() in the error handling case.

Fixes: abf42d2f ("tty: serial: owl: add "much needed" clk_prepare_enable()")
Signed-off-by: Miaoqian Lin <linmq006@gmail.com>
Link: https://lore.kernel.org/r/20220307105135.11698-1-linmq006@gmail.comSigned-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

The console_write and IRQ handler can run concurrently.
Problems may occurs console_write is continuously executed while
the IRQ handler is running.
Reviewed-by: Jiri Slaby <jirislaby@kernel.org>
Signed-off-by: Jaewon Kim <jaewon02.kim@samsung.com>
Link: https://lore.kernel.org/r/20220407071619.102249-2-jaewon02.kim@samsung.comSigned-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

When pci_read_config_dword failed, call pci_release_regions() and
pci_disable_device() to recycle the resource previously allocated.
Reviewed-by: Jiri Slaby <jirislaby@kernel.org>
Signed-off-by: Huang Guobin <huangguobin4@huawei.com>
Link: https://lore.kernel.org/r/20220331091005.3290753-1-huangguobin4@huawei.comSigned-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

powerpc's asm/prom.h brings some headers that it doesn't
need itself.

In order to clean it up, first add missing headers in
users of asm/prom.h
Reviewed-by: Jiri Slaby <jirislaby@kernel.org>
Signed-off-by: Christophe Leroy <christophe.leroy@csgroup.eu>
Link: https://lore.kernel.org/r/49fc0d4b6446da630b1e9f29c4bab38f8ed087bf.1648833419.git.christophe.leroy@csgroup.euSigned-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

powerpc's asm/prom.h brings some headers that it doesn't
need itself.

In order to clean it up, first add missing headers in
users of asm/prom.h
Signed-off-by: Christophe Leroy <christophe.leroy@csgroup.eu>
Link: https://lore.kernel.org/r/8b3dbd25bbeb7949e1b0a2170fee7b9cc5a6f806.1648833418.git.christophe.leroy@csgroup.euSigned-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

In goldfish_tty_probe(), the port initialized through tty_port_init()
should be destroyed in error paths.In goldfish_tty_remove(), qtty->port
also should be destroyed or else might leak resources.

Fix the above by calling tty_port_destroy().

Fixes: 666b7793 ("goldfish: tty driver")
Reviewed-by: Jiri Slaby <jirislaby@kernel.org>
Signed-off-by: Wang Weiyang <wangweiyang2@huawei.com>
Link: https://lore.kernel.org/r/20220328115844.86032-1-wangweiyang2@huawei.comSigned-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

altera_jtaguart_tx_chars() duplicates what altera_jtaguart_stop_tx()
already does. So instead of the duplication, call the helper instead.

Not only it makes the code cleaner, but it also says what the "if"
really does.

Cc: Tobias Klauser <tklauser@distanz.ch>
Acked-by: Tobias Klauser <tklauser@distanz.ch>
Signed-off-by: Jiri Slaby <jslaby@suse.cz>
Link: https://lore.kernel.org/r/20220411104506.8990-4-jslaby@suse.czSigned-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Flow control characters should be sent even if the TX is stopped. So fix
owl-uart to behave the same as other drivers.

This unification also allows the use of the TX helper in the future.

Cc: "Andreas Färber" <afaerber@suse.de>
Cc: Manivannan Sadhasivam <mani@kernel.org>
Signed-off-by: Jiri Slaby <jslaby@suse.cz>
Link: https://lore.kernel.org/r/20220411104506.8990-3-jslaby@suse.czSigned-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

The code now contains:
 #ifdef CONFIG_PPC_MPC512x
 ...
 #endif

 #ifdef CONFIG_PPC_MPC512x
 ...
 #endif

So remove the endif+ifdef from the middle, provided it's about the same
define.
Signed-off-by: Jiri Slaby <jslaby@suse.cz>
Link: https://lore.kernel.org/r/20220411104506.8990-2-jslaby@suse.czSigned-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

When the driver fails at alloc_hdlcdev(), and then we remove the driver
module, we will get the following splat:

[   25.065966] general protection fault, probably for non-canonical address 0xdffffc0000000182: 0000 [#1] PREEMPT SMP KASAN PTI
[   25.066914] KASAN: null-ptr-deref in range [0x0000000000000c10-0x0000000000000c17]
[   25.069262] RIP: 0010:detach_hdlc_protocol+0x2a/0x3e0
[   25.077709] Call Trace:
[   25.077924]  <TASK>
[   25.078108]  unregister_hdlc_device+0x16/0x30
[   25.078481]  slgt_cleanup+0x157/0x9f0 [synclink_gt]

Fix this by checking whether the 'info->netdev' is a null pointer first.
Reviewed-by: Jiri Slaby <jirislaby@kernel.org>
Signed-off-by: Zheyu Ma <zheyuma97@gmail.com>
Link: https://lore.kernel.org/r/20220410114814.3920474-1-zheyuma97@gmail.comSigned-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Reformat the whole document, so that automatic numbering and TOC is
properly generated.
Signed-off-by: Jiri Slaby <jslaby@suse.cz>
Link: https://lore.kernel.org/r/20220411110143.10019-7-jslaby@suse.czSigned-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

All of the URLs give 404. There is a little point to preserve them. If
really need be, we could try archive.org if the documents are not there
by a chance.
Signed-off-by: Jiri Slaby <jslaby@suse.cz>
Link: https://lore.kernel.org/r/20220411110143.10019-6-jslaby@suse.czSigned-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

It is a tty_driver, not serial -- uart_driver. So move it to the tty
docs dir too. (The same as the driver itself.)
Signed-off-by: Jiri Slaby <jslaby@suse.cz>
Link: https://lore.kernel.org/r/20220411110143.10019-5-jslaby@suse.czSigned-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

We have n_tty documented in Documentation/driver-api/tty/. n_gsm belongs
there too, so move from serial/ to tty/ too.
Signed-off-by: Jiri Slaby <jslaby@suse.cz>
Link: https://lore.kernel.org/r/20220411110143.10019-4-jslaby@suse.czSigned-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

So far only n_tty belongs here, but in the next patches, more will come.
Signed-off-by: Jiri Slaby <jslaby@suse.cz>
Link: https://lore.kernel.org/r/20220411110143.10019-3-jslaby@suse.czSigned-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Based on discussion starting as 87mthw2o93.fsf@meer.lwn.net, let's move
the tty documentation to driver-api. It's more appropriate there.

Cc: Jonathan Corbet <corbet@lwn.net>
Signed-off-by: Jiri Slaby <jslaby@suse.cz>
Link: https://lore.kernel.org/r/20220411110143.10019-2-jslaby@suse.czSigned-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Pull serial driver fix from Greg KH:
 "This is a single serial driver fix for a build issue that showed up
  due to changes that came in through the tty tree in 5.18-rc1 that were
  missed previously. It resolves a build error with the mpc52xx_uart
  driver.

  It has been in linux-next this week with no reported problems"

* tag 'tty-5.18-rc2' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/tty:
  tty: serial: mpc52xx_uart: make rx/tx hooks return unsigned, part II.

Pull staging driver fix from Greg KH:
 "Here is a single staging driver fix for 5.18-rc2 that resolves an
  endian issue for the r8188eu driver. It has been in linux-next all
  this week with no reported problems"

* tag 'staging-5.18-rc2' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/staging:
  staging: r8188eu: Fix PPPoE tag insertion on little endian systems

Merge tag 'driver-core-5.18-rc2' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/driver-core

Pull driver core updates from Greg KH:
 "Here are two small driver core changes for 5.18-rc2.

  They are the final bits in the removal of the default_attrs field in
  struct kobj_type. I had to wait until after 5.18-rc1 for all of the
  changes to do this came in through different development trees, and
  then one new user snuck in. So this series has two changes:

   - removal of the default_attrs field in the powerpc/pseries/vas code.

     The change has been acked by the PPC maintainers to come through
     this tree

   - removal of default_attrs from struct kobj_type now that all
     in-kernel users are removed.

     This cleans up the kobject code a little bit and removes some
     duplicated functionality that confused people (now there is only
     one way to do default groups)

  Both of these have been in linux-next for all of this week with no
  reported problems"

* tag 'driver-core-5.18-rc2' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/driver-core:
  kobject: kobj_type: remove default_attrs
  powerpc/pseries/vas: use default_groups in kobj_type