Use if and else instead of if(A) and if (!A) and fix a coding style.
Signed-off-by: Wan Jiabing <wanjiabing@vivo.com>
Link: https://lore.kernel.org/r/20220424091310.98780-1-wanjiabing@vivo.comSigned-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Use if and else instead of if(A) and if (!A).
Reviewed-by: Jiri Slaby <jirislaby@kernel.org>
Signed-off-by: Wan Jiabing <wanjiabing@vivo.com>
Link: https://lore.kernel.org/r/20220426071041.168282-1-wanjiabing@vivo.comSigned-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Add early console support in stm32 uart driver.
Signed-off-by: Alexandre Torgue <alexandre.torgue@foss.st.com>
Signed-off-by: Valentin Caron <valentin.caron@foss.st.com>
Link: https://lore.kernel.org/r/20220419085330.1178925-4-valentin.caron@foss.st.comSigned-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Add support for KGDB in stm32 serial driver by implementing characters
polling callbacks (poll_init, poll_get_char and poll_put_char).
Signed-off-by: Erwan Le Ray <erwan.leray@foss.st.com>
Signed-off-by: Jean Philippe Romain <jean-philippe.romain@foss.st.com>
Signed-off-by: Valentin Caron <valentin.caron@foss.st.com>
Link: https://lore.kernel.org/r/20220419085330.1178925-3-valentin.caron@foss.st.comSigned-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Rework stm32_usart_console_putchar() function in order to anticipate
the case where the character can never be sent.
Signed-off-by: Valentin Caron <valentin.caron@foss.st.com>
Link: https://lore.kernel.org/r/20220419085330.1178925-2-valentin.caron@foss.st.comSigned-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Move receive path flow control character handling to own function.

No functional changes.
Signed-off-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>
Link: https://lore.kernel.org/r/20220411094859.10894-2-ilpo.jarvinen@linux.intel.comSigned-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Do not set timeout to twice the approximate amount of time to send the
entire FIFO if CTS is enabled. If the caller requested no timeout, e.g.
when userspace program called tcdrain(), then wait without any timeout.

Premature return from tcdrain() was observed on imx based system which
has 32 character long transmitter FIFO with hardware CTS handling.

Simple userspace application that reproduces problem has to:
  * Open tty device, enable hardware flow control (CRTSCTS)
  * Write data, e.g. 26 bytes
  * Call tcdrain() to wait for the transmitter
  * Close tty device

The other side of serial connection has to:
  * Receive some data, e.g. 10 bytes
  * Set RTS output (CTS input from sender perspective) inactive for
    at least twice the port timeout
  * Try to receive remaining data

Without this patch, userspace application will finish without any error
while the other side of connection will never receive remaining data.
Signed-off-by: Tomasz Moń <tomasz.mon@camlingroup.com>
Link: https://lore.kernel.org/r/20220228054911.1420221-1-tomasz.mon@camlingroup.comSigned-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Register a console in the ttyprintk driver so that it can be selected
for /dev/console with console=ttyprintk on the kernel command line,
similar to other console drivers.
Signed-off-by: Vincent Whitchurch <vincent.whitchurch@axis.com>
Link: https://lore.kernel.org/r/20220215141750.92808-1-vincent.whitchurch@axis.comSigned-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Note: I am using a small test app + driver located at [0] for the
problem description. serco is a driver whose write function dispatches
to the serial controller. sertest is a user-mode app that writes n bytes
to the serial console using the serco driver.

While investigating a bug in the RHEL kernel, I noticed that the serial
console throughput is way below the configured speed of 115200 bps in
a HP Proliant DL380 Gen9. I was expecting something above 10KB/s, but
I got 2.5KB/s.

$ time ./sertest -n 2500 /tmp/serco

real    0m0.997s
user    0m0.000s
sys     0m0.997s

With the help of the function tracer, I then noticed the serial
controller was taking around 410us seconds to dispatch one single byte:

$ trace-cmd record -p function_graph -g serial8250_console_write \
   ./sertest -n 1 /tmp/serco

$ trace-cmd report

            |  serial8250_console_write() {
 0.384 us   |    _raw_spin_lock_irqsave();
 1.836 us   |    io_serial_in();
 1.667 us   |    io_serial_out();
            |    uart_console_write() {
            |      serial8250_console_putchar() {
            |        wait_for_xmitr() {
 1.870 us   |          io_serial_in();
 2.238 us   |        }
 1.737 us   |        io_serial_out();
 4.318 us   |      }
 4.675 us   |    }
            |    wait_for_xmitr() {
 1.635 us   |      io_serial_in();
            |      __const_udelay() {
 1.125 us   |        delay_tsc();
 1.429 us   |      }
...
...
...
 1.683 us   |      io_serial_in();
            |      __const_udelay() {
 1.248 us   |        delay_tsc();
 1.486 us   |      }
 1.671 us   |      io_serial_in();
 411.342 us |    }

In another machine, I measured a throughput of 11.5KB/s, with the serial
controller taking between 80-90us to send each byte. That matches the
expected throughput for a configuration of 115200 bps.

This patch changes the serial8250_console_write to use the 16550 fifo
if available. In my benchmarks I got around 25% improvement in the slow
machine, and no performance penalty in the fast machine.
Signed-off-by: Wander Lairson Costa <wander@redhat.com>
Link: https://lore.kernel.org/r/20220411174841.34936-2-wander@redhat.comSigned-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

There is a deadlock in sa1100_set_termios(), which is shown
below:

   (Thread 1)              |      (Thread 2)
                           | sa1100_enable_ms()
sa1100_set_termios()       |  mod_timer()
 spin_lock_irqsave() //(1) |  (wait a time)
 ...                       | sa1100_timeout()
 del_timer_sync()          |  spin_lock_irqsave() //(2)
 (wait timer to stop)      |  ...

We hold sport->port.lock in position (1) of thread 1 and
use del_timer_sync() to wait timer to stop, but timer handler
also need sport->port.lock in position (2) of thread 2. As a result,
sa1100_set_termios() will block forever.

This patch moves del_timer_sync() before spin_lock_irqsave()
in order to prevent the deadlock.
Signed-off-by: Duoming Zhou <duoming@zju.edu.cn>
Link: https://lore.kernel.org/r/20220417111626.7802-1-duoming@zju.edu.cnSigned-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

The definition of sysrq_key_table's elements, like sysrq_thaw_op and
sysrq_showallcpus_op are not consistent with sysrq_ftrace_dump_op,
Consistency makes code more readable.
Reviewed-by: Jiri Slaby <jirislaby@kernel.org>
Signed-off-by: Junwen Wu <wudaemon@gmail.com>
Link: https://lore.kernel.org/r/20220418153703.97705-1-wudaemon@163.comSigned-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

No need to initialize the count variable in lpuart_copy_rx_to_tty(),
so let's remove it here.
Reviewed-by: Jiri Slaby <jirislaby@kernel.org>
Signed-off-by: Sherry Sun <sherry.sun@nxp.com>
Link: https://lore.kernel.org/r/20220418021844.29591-1-sherry.sun@nxp.comSigned-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Some more serial drivers can be compile-tested under certain
circumstances (when building a specific architecture). So allow for
that.

This reduces the need of zillion mach/subarch-specific configs. And
since the 0day bot has only allmodconfig's for some archs, this
increases build coverage there too.

Note that cpm needs a minor update in the header, so that it drags in
at least some defines (CPM2 ones).
Signed-off-by: Jiri Slaby <jslaby@suse.cz>
Link: https://lore.kernel.org/r/20220421101708.5640-8-jslaby@suse.czSigned-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

pic32_uart contains this:
  #ifdef CONFIG_SERIAL_PIC32_CONSOLE
  ...
  console_initcall(pic32_console_init);
  ...
  core_initcall(pic32_late_console_init);
  ...
  #endif
  ...
  arch_initcall(pic32_uart_init);

When the driver is built as module, all three above become
module_init(). So if SERIAL_PIC32_CONSOLE is set while SERIAL_PIC32=m,
it results in the following build error:
  In file included from include/linux/device/driver.h:21,
                   from include/linux/device.h:32,
                   from include/linux/platform_device.h:13,
                   from drivers/tty/serial/pic32_uart.c:12:
  include/linux/module.h:131:49: error: redefinition of '__inittest'

So make sure SERIAL_PIC32_CONSOLE can be set only when SERIAL_PIC32=y --
similar as for other drivers.
Signed-off-by: Jiri Slaby <jslaby@suse.cz>
Link: https://lore.kernel.org/r/20220421101708.5640-7-jslaby@suse.czSigned-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

The code wants to know if the circ buffer is empty, so use the proper
macro.

No functional change intended, just saner function name used for that
use case.

Cc: Andy Gross <agross@kernel.org>
Cc: Bjorn Andersson <bjorn.andersson@linaro.org>
Signed-off-by: Jiri Slaby <jslaby@suse.cz>
Link: https://lore.kernel.org/r/20220421101708.5640-6-jslaby@suse.czSigned-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

struct uart_port::membase is declared as a pointer. So it should be
initialized by NULL, not zero constant.
Signed-off-by: Jiri Slaby <jslaby@suse.cz>
Link: https://lore.kernel.org/r/20220421101708.5640-5-jslaby@suse.czSigned-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Cache port->state->xmit into a local variable (xmit) in
cdns_uart_handle_tx(). This reduces length of some lines there
significantly. I.e. makes the code more readable.
Signed-off-by: Jiri Slaby <jslaby@suse.cz>
Link: https://lore.kernel.org/r/20220421101708.5640-4-jslaby@suse.czSigned-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Return from the true branch of the 'if'. This saves one indentation
level and makes the code more readable.

The two comments about what obvious code does are removed too.
Signed-off-by: Jiri Slaby <jslaby@suse.cz>
Link: https://lore.kernel.org/r/20220421101708.5640-3-jslaby@suse.czSigned-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Smatch reports this issue
sunplus-uart.c:501:26: warning: symbol 'sunplus_console_ports' was not declared. Should it be static?

sunplus_console_ports is only used in sunplus-uart.c so change
its storage-class specifier to static
Reviewed-by: Jiri Slaby <jirislaby@kernel.org>
Signed-off-by: Tom Rix <trix@redhat.com>
Link: https://lore.kernel.org/r/20220421152505.1531507-1-trix@redhat.comSigned-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Make UART driver compatible with S4 SOC UART. Meanwhile, the S4 SOC
UART uses 12MHz as the clock source for baud rate calculations.
Reviewed-by: Neil Armstrong <narmstrong@baylibre.com>
Signed-off-by: Yu Tu <yu.tu@amlogic.com>
Link: https://lore.kernel.org/r/20220422111320.19234-3-yu.tu@amlogic.comSigned-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

tty: serial: meson: Add a 12MHz internal clock rate to calculate baud rate in order to meet the baud rate requirements of special BT modules

A /2 divider over XTAL was introduced since G12A, and is preferred
to be used over the still present /3 divider since it provides much
closer frequencies vs the request baudrate. Especially the BT module
uses 3Mhz baud rate. 8Mhz calculations can lead to baud rate bias,
causing some problems.
Reviewed-by: Neil Armstrong <narmstrong@baylibre.com>
Signed-off-by: Yu Tu <yu.tu@amlogic.com>
Link: https://lore.kernel.org/r/20220422111320.19234-2-yu.tu@amlogic.comSigned-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Some members of struct icom_port are completely unused or only set and
never read. Remove all those.
Signed-off-by: Jiri Slaby <jslaby@suse.cz>
Link: https://lore.kernel.org/r/20220421085808.24152-11-jslaby@suse.czSigned-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

uart_ops::release_port() and uart_ops::request_port() are not required
by the serial layer. So no need to define empty ones.

Remove them.
Signed-off-by: Jiri Slaby <jslaby@suse.cz>
Link: https://lore.kernel.org/r/20220421085808.24152-10-jslaby@suse.czSigned-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Use list_for_each_entry() helper instead of explicit combo of
list_for_each() and list_entry().

Note that pos is used as a reference point in list_add_tail() in
icom_alloc_adapter(). This functionality remains as with an empty list,
cur_adapter_entry->icom_adapter_entry is still the list head.

This simplifies the code a bit.
Signed-off-by: Jiri Slaby <jslaby@suse.cz>
Link: https://lore.kernel.org/r/20220421085808.24152-9-jslaby@suse.czSigned-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

The baud rates are unsigned constants. So mark them as such.

Not only it makes sense, but they are passed also to
uart_get_baud_rate() and that expects unsigned int as baud rates on
input.
Signed-off-by: Jiri Slaby <jslaby@suse.cz>
Link: https://lore.kernel.org/r/20220421085808.24152-8-jslaby@suse.czSigned-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Signed-off-by: Jiri Slaby <jslaby@suse.cz>
Link: https://lore.kernel.org/r/20220421085808.24152-7-jslaby@suse.czSigned-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

There is no point keeping the header content separated. The header was
not even protected against double inclusion. So move the content to the
appropriate source file.
Signed-off-by: Jiri Slaby <jslaby@suse.cz>
Link: https://lore.kernel.org/r/20220421085808.24152-6-jslaby@suse.czSigned-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

There is a lot of sparse warnings:
  .../icom.c:228:30: warning: cast from restricted __le16
  .../icom.c:232:66: warning: incorrect type in assignment (different base types)
  .../icom.c:232:66:    expected unsigned int [usertype] leBuffer
  .../icom.c:232:66:    got restricted __le32 [usertype]
  .../icom.c:237:30: warning: cast from restricted __le16
  ...
  .../icom.c:1228:22: warning: cast from restricted __le16

And they are correct. So sort them all out by using proper __leXX and
uXX types and the right direction of conversion: le16_to_cpu() instead
of cpu_to_le16(), where appropriate.
Signed-off-by: Jiri Slaby <jslaby@suse.cz>
Link: https://lore.kernel.org/r/20220421085808.24152-5-jslaby@suse.czSigned-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Integrate both the to_icom_adapter() macro and icom_kref_release()
wrapper into icom_remove_adapter(). (And keep it icom_kref_release()
name.)

It makes the code easier to follow without complex indirections.
Signed-off-by: Jiri Slaby <jslaby@suse.cz>
Link: https://lore.kernel.org/r/20220421085808.24152-4-jslaby@suse.czSigned-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

In icom, there is an ICOM_PORT macro to perform upcasts from struct
uart_port to struct icom_port. It's not completely safe and it works
only because the first member of icom_port is uart_port. Nowadays, we
use container_of for such an upcast instead.

So introduce a helper (to_icom_port()) with container_of in it and
convert all the ICOM_PORT users to the new helper. Apart from the code
and type safety, it's also clear what icom_port (the variable) is.
Unlike with the old ICOM_PORT (the macro with the cast).
Signed-off-by: Jiri Slaby <jslaby@suse.cz>
Link: https://lore.kernel.org/r/20220421085808.24152-3-jslaby@suse.czSigned-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

It's unused, so remove the macro.
Signed-off-by: Jiri Slaby <jslaby@suse.cz>
Link: https://lore.kernel.org/r/20220421085808.24152-2-jslaby@suse.czSigned-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

The moxa-smartio.rst file was moved to a different location,
so update the MAINTAINERS file entry for it.

Quietens one build warning:

MAINTAINERS:29715: WARNING: unknown document: ../driver-api/serial/moxa-smartio

Fixes: 5b437ae9 ("Documentation: tty: move moxa-smartio.rst to tty")
Cc: Jiri Slaby <jirislaby@kernel.org>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Reported-by: Stephen Rothwell <sfr@canb.auug.org.au>
Reviewed-by: Jiri Slaby <jirislaby@kernel.org>
Signed-off-by: Randy Dunlap <rdunlap@infradead.org>
Link: https://lore.kernel.org/r/20220420235545.17081-1-rdunlap@infradead.orgSigned-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

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 5.2.1.2 describes the encoding of the
address field within the frame header. It is made up of the DLCI address,
command/response (CR) bit and EA bit.
Use the predefined CR value instead of a plain 2 in alignment to the
remaining code and to make the encoding obvious.
Signed-off-by: Daniel Starke <daniel.starke@siemens.com>
Link: https://lore.kernel.org/r/20220420101346.3315-3-daniel.starke@siemens.comSigned-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Remove commented out code as it is never used and if anyone accidentally
turned it on, it would be broken.
Signed-off-by: Daniel Starke <daniel.starke@siemens.com>
Link: https://lore.kernel.org/r/20220420101346.3315-2-daniel.starke@siemens.comSigned-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

This partially reverts commit f6f58610. The code added by
that commit containted math overflow for 32-bit archs. In
addition, the approach used in it is unnecessarily complicated
requiring a dedicated timer just for notemt. A simpler approach
for providing UART_CAP_NOTEMT already exists (patches 1-2):
  https://lore.kernel.org/linux-serial/20220411083321.9131-3-ilpo.jarvinen@linux.intel.com/T/#u
Thus, simply revert the UART_CAP_NOTEMT change for now.

There were two driver changes within the patch series adding
UART_CAP_NOTEMT taking advantage of the newly added flag.
This does not revert the driver changes and therefore also
UART_CAP_NOTEMT define has to remain. UART_CAP_NOTEMT remains
no-op until support is again added.

Fixes: f6f58610 ("serial: 8250: Handle UART without interrupt on TEMT using em485")
Signed-off-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>
Link: https://lore.kernel.org/r/5f874142-fb1f-bff7-f33-fac823e65e2e@linux.intel.comSigned-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

The commit below causes the following warnings:
Documentation/driver-api/index.rst:14: WARNING: toctree contains reference to nonexisting document 'driver-api/tty'
Documentation/driver-api/tty/index.rst: WARNING: document isn't included in any toctree

This is because I omitted the "/index" part from the link. That part is
needed for directories and I was confused by the surrounding links which
are links to files. Fix it in this patch.

Fixes: b96cd8b0 ("Documentation: move tty to driver-api")
Cc: Jonathan Corbet <corbet@lwn.net>
Reported-by: Stephen Rothwell <sfr@canb.auug.org.au>
Signed-off-by: Jiri Slaby <jslaby@suse.cz>
Link: https://lore.kernel.org/r/20220419074302.29632-1-jslaby@suse.czSigned-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Now fsl_lpuart driver use both of_alias_get_id() and ida_simple_get() in
.probe(), which has the potential bug. For example, when remove the
lpuart7 alias in dts, of_alias_get_id() will return error, then call
ida_simple_get() to allocate the id 0 for lpuart7, this may confilct
with the lpuart4 which has alias 0.

    aliases {
	...
        serial0 = &lpuart4;
        serial1 = &lpuart5;
        serial2 = &lpuart6;
        serial3 = &lpuart7;
    }

So remove the ida_simple_get() in .probe(), return an error directly
when calling of_alias_get_id() fails, which is consistent with other
uart drivers behavior.

Fixes: 3bc3206e ("serial: fsl_lpuart: Remove the alias node dependence")
Signed-off-by: Sherry Sun <sherry.sun@nxp.com>
Link: https://lore.kernel.org/r/20220321112211.8895-1-sherry.sun@nxp.comSigned-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

When flow control is enabled, the UART should set RTS to false
during suspend to stop incoming data. Currently, the suspend
routine sets the mctrl register in the uart to zero, but leaves
the shadow version in the uart_port struct alone so that resume
can restore it. This causes a problem later in suspend when
serial8250_do_shutdown() is called which uses the shadow mctrl
register to clear some additional bits but ends up restoring RTS.
The solution is to clear RTS from the shadow version before
serial8250_do_shutdown() is called and restore it after.
Signed-off-by: Al Cooper <alcooperx@comcast.net>
Link: https://lore.kernel.org/r/20220324145620.41573-1-alcooperx@gmail.comSigned-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Signed-off-by: Eric Tremblay <etremblay@distech-controls.com>
Signed-off-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
Link: https://lore.kernel.org/r/20220330104642.229507-4-u.kleine-koenig@pengutronix.deSigned-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

The Freescale variant of the 16550A doesn't have an interrupt on TEMT
available when using the FIFO mode.
Signed-off-by: Eric Tremblay <etremblay@distech-controls.com>
Signed-off-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
Link: https://lore.kernel.org/r/20220330104642.229507-3-u.kleine-koenig@pengutronix.deSigned-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>