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 5.1.8.1.1 describes the parameter negotiation
messages and parameters. Chapter 5.4.1 states that the default parameters
are to be used if no negotiation is performed. Chapter 5.4.6.3.1 describes
the encoding of the parameter negotiation message. The meaning of the
parameters and allowed value ranges can be found in chapter 5.7.

Add parameter negotiation support accordingly. DLCI specific parameter
configuration by the user requires additional ioctls. This is subject to
another patch.
Signed-off-by: Daniel Starke <daniel.starke@siemens.com>
Reviewed-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>
Link: https://lore.kernel.org/r/20221103091743.2119-3-daniel.starke@siemens.comSigned-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 5.4.6.3.1 describes the encoding of the
parameter negotiation messages.

Add the parameters used there to 'gsm_mux' and 'gsm_dlci' and initialize both
according to the value ranges and recommended defaults defined in chapter 5.7.

Replace the use of the DLC default values from the 'gsm_mux' fields with the DLC
specific values from the 'gsm_dlci' fields where applicable.
Signed-off-by: Daniel Starke <daniel.starke@siemens.com>
Link: https://lore.kernel.org/r/20221103091743.2119-2-daniel.starke@siemens.comSigned-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

n_gsm has a minimal protocol overhead of 7 bytes. The current code already
checks whether the configured MRU/MTU size is at least one byte more than
this.

Introduce the macro MIN_MTU to make this value more obvious.
Signed-off-by: Daniel Starke <daniel.starke@siemens.com>
Link: https://lore.kernel.org/r/20221103091743.2119-1-daniel.starke@siemens.comSigned-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Commit 801954d1 ("serial: 8250: 8250_omap: Support native RS485")
calculates RS485 delays from the baudrate.  The baudrate is generated
with either a 16x or 13x divisor.  The divisor is set in the Mode
Definition Register 1 (MDR1).

The commit erroneously assumes that the register stores the divisor as
a bitmask and uses a logical AND to differentiate between 16x and 13x
divisors.  However the divisor is really stored as a 3-bit mode
(see lines 363ff in include/uapi/linux/serial_reg.h).

The logical AND operation is performed with UART_OMAP_MDR1_16X_MODE,
which is defined as 0x0 and hence yields false.  So the commit always
assumes a 13x divisor.  Fix by using an equal comparison.  This works
because we never set any of the other 5 bits in the register.  (They
pertain to IrDA mode, which is not supported by the driver).

Fixes: 801954d1 ("serial: 8250: 8250_omap: Support native RS485")
Link: https://lore.kernel.org/linux-serial/202211070440.8hWunFUN-lkp@intel.com/Reported-by: kernel test robot <lkp@intel.com>
Reported-by: Dan Carpenter <error27@gmail.com>
Signed-off-by: Lukas Wunner <lukas@wunner.de>
Reviewed-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>
Link: https://lore.kernel.org/r/7d5b04da13d89b8708b9543a0b125f2b6062a77b.1667977259.git.lukas@wunner.deSigned-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

A problem about 8250_bcm7271 create debugfs failed is triggered with the
following log given:

 [  324.516635] debugfs: Directory 'bcm7271-uart' with parent '/' already present!

The reason is that brcmuart_init() returns platform_driver_register()
directly without checking its return value, if platform_driver_register()
failed, it returns without destroy the newly created debugfs, resulting
the debugfs of 8250_bcm7271 can never be created later.

 brcmuart_init()
   debugfs_create_dir() # create debugfs directory
   platform_driver_register()
     driver_register()
       bus_add_driver()
         priv = kzalloc(...) # OOM happened
   # return without destroy debugfs directory

Fix by removing debugfs when platform_driver_register() returns error.

Fixes: 41a46948 ("serial: 8250: Add new 8250-core based Broadcom STB driver")
Signed-off-by: Yuan Can <yuancan@huawei.com>
Link: https://lore.kernel.org/r/20221109072110.117291-2-yuancan@huawei.comSigned-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

When DMA Rx completes, the current behavior is to just exit the DMA
completion handler without future actions. If the transfer is still
on-going, UART will trigger an interrupt and that eventually rearms the
DMA Rx. The extra interrupt round-trip has an inherent latency cost
that increases the risk of FIFO overrun. In such situations, the
latency margin tends to already be less due to FIFO not being empty.

Add check into DMA Rx completion handler to detect if LSR has DR (Data
Ready) still set. DR indicates there will be more characters pending
and DMA Rx can be rearmed right away to handle them.

Cc: Gilles BULOZ <gilles.buloz@kontron.com>
Signed-off-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>
Reviewed-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Link: https://lore.kernel.org/r/20221107102126.56481-1-ilpo.jarvinen@linux.intel.comSigned-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Fix the two instances of this typo present in the MSM and VT8500 serial
drivers.
Signed-off-by: Jonathan Neuschäfer <j.neuschaefer@gmx.net>
Reviewed-by: Mukesh Ojha <quic_mojha@quicinc.com>
Acked-by: Konrad Dybcio <konrad.dybcio@somainline.org>
Link: https://lore.kernel.org/r/20221104103719.2234098-1-j.neuschaefer@gmx.netSigned-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

The struct tty_buffer has flags which is only used for storing TTYB_NORMAL.
There is also a few quite confusing operations for checking the presense
of TTYB_NORMAL. Simplify things by converting flags to bool.

Despite the name remaining the same, the meaning of "flags" is altered
slightly by this change. Previously it referred to flags of the buffer
(only TTYB_NORMAL being used as a flag). After this change, flags tell
whether the buffer contains/should be allocated with flags array along
with character data array. It is much more suitable name that
TTYB_NORMAL was for this purpose, thus the name remains.
Signed-off-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>
Link: https://lore.kernel.org/r/20221019105504.16800-1-ilpo.jarvinen@linux.intel.comSigned-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

The variable "tty_legacy_tiocsti" should be defined before the kerndoc
for the tiocsti() function. The new variable was breaking the "htmldocs"
build target:

drivers/tty/tty_io.c:2271: warning: cannot understand function prototype: 'bool tty_legacy_tiocsti __read_mostly = IS_ENABLED(CONFIG_LEGACY_TIOCSTI); '

Fixes: 83efeeeb ("tty: Allow TIOCSTI to be disabled")
Reported-by: Stephen Rothwell <sfr@canb.auug.org.au>
Link: https://lore.kernel.org/lkml/20221107143434.66f7be35@canb.auug.org.au
Cc: Jiri Slaby <jirislaby@kernel.org>
Signed-off-by: Kees Cook <keescook@chromium.org>
Acked-by: Randy Dunlap <rdunlap@infradead.org>
Link: https://lore.kernel.org/r/20221107034631.never.637-kees@kernel.orgSigned-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Don't use decimal for mask. Don't use literal for aligning.
Signed-off-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>
Link: https://lore.kernel.org/r/20221019105504.16800-2-ilpo.jarvinen@linux.intel.comSigned-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Document support for the Serial Communication Interface with FIFO (SCIF)
in the Renesas R-Car V4H (R8A779G0) SoC.
Reviewed-by: Wolfram Sang <wsa+renesas@sang-engineering.com>
Acked-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
Link: https://lore.kernel.org/r/8a2d04651f04a97d652395b4d933af5c3c8d5b5b.1666360789.git.geert+renesas@glider.beSigned-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

The symbol is not used outside of the file, so mark it static.

Fixes the following warning:

drivers/tty/hvc/hvc_rtas.c:29:19: warning: symbol 'hvc_rtas_dev' was
not declared. Should it be static?
Reviewed-by: Jiri Slaby <jirislaby@kernel.org>
Signed-off-by: ruanjinjie <ruanjinjie@huawei.com>
Link: https://lore.kernel.org/r/20221019064412.3759874-1-ruanjinjie@huawei.comSigned-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Use str_enabled_disabled() helper instead of open coding the same.
Reviewed-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>
Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Link: https://lore.kernel.org/r/20221017171633.65275-1-andriy.shevchenko@linux.intel.comSigned-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

The default polarity of RS485 DE signal is active high. This driver does
not handle such case properly. Currently, when a pin is multiplexed as a
UART CTS_B on boot, this pin is pulled HIGH by the i.MX UART CTS circuit,
which activates DE signal on the RS485 transceiver and thus behave as if
the RS485 was transmitting data, so the system blocks the RS485 bus when
it starts and until user application takes over. This behavior is not OK.
The problem consists of two separate parts.

First, the i.MX UART IP requires UCR1 UARTEN and UCR2 RXEN to be set for
UCR2 CTSC and CTS bits to have any effect. The UCR2 CTSC bit permits the
driver to set CTS (RTS_B or RS485 DE signal) to either level sychronous
to the internal UART IP clock. Compared to other options, like GPIO CTS
control, this has the benefit of being synchronous to the UART IP clock
and thus without glitches or bus delays. The reason for the CTS design
is likely because when the Receiver is disabled, the UART IP can never
indicate that it is ready to receive data by assering CTS signal, so
the CTS is always pulled HIGH by default.

When the port is closed by user space, imx_uart_stop_rx() clears UCR2
RXEN bit, and imx_uart_shutdown() clears UCR1 UARTEN bit. This disables
UART Receiver and UART itself, and forces CTS signal HIGH, which leads
to the RS485 bus being blocked because RS485 DE is incorrectly active.

The proposed solution for this problem is to keep the Receiver running
even after the port is closed, but in loopback mode. This disconnects
the RX FIFO input from the RXD external signal, and since UCR2 TXEN is
cleared, the UART Transmitter is disabled, so nothing can feed data in
the RX FIFO. Because the Receiver is still enabled, the UCR2 CTSC and
CTS bits still have effect and the CTS (RS485 DE) control is retained.

Note that in case of RS485 DE signal active low, there is no problem and
no special handling is necessary. The CTS signal defaults to HIGH, thus
the RS485 is by default set to Receive and the bus is not blocked.

Note that while there is the possibility to control CTS using GPIO with
either CTS polarity, this has the downside of not being synchronous to
the UART IP clock and thus glitchy and susceptible to slow DE switching.

Second, on boot, before the UART driver probe callback is called, the
driver core triggers pinctrl_init_done() and configures the IOMUXC to
default state. At this point, UCR1 UARTEN and UCR2 RXEN are both still
cleared, but UART CTS_B (RS485 DE) is configured as CTS function, thus
the RTS signal is pulled HIGH by the UART IP CTS circuit.

One part of the solution here is to enable UCR1 UARTEN and UCR2 RXEN and
UTS loopback in this driver probe callback, thus unblocking the CTSC and
CTS control early on. But this is still too late, since the pin control
is already configured and CTS has been pulled HIGH for a short period
of time.

When Linux kernel boots and this driver is bound, the pin control is set
to special "init" state if the state is available, and driver can switch
the "default" state afterward when ready. This state can be used to set
the CTS line as a GPIO in DT temporarily, and a GPIO hog can force such
GPIO to LOW, thus keeping the RS485 DE line LOW early on boot. Once the
driver takes over and UCR1 UARTEN and UCR2 RXEN and UTS loopback are all
enabled, the driver can switch to "default" pin control state and control
the CTS line as function instead. DT binding example is below:

"
&gpio6 {
  rts-init-hog {
    gpio-hog;
    gpios = <5 0>;
    output-low;
    line-name = "rs485-de";
  };
};

&uart5 { /* DHCOM UART2 */
  pinctrl-0 = <&pinctrl_uart5>;
  pinctrl-1 = <&pinctrl_uart5_init>;
  pinctrl-names = "default", "init";
  ...
};
pinctrl_uart5_init: uart5-init-grp {
  fsl,pins = <
...
    MX6QDL_PAD_CSI0_DAT19__GPIO6_IO05       0x30b1
  >;
};

pinctrl_uart5: uart5-grp {
  fsl,pins = <
...
    MX6QDL_PAD_CSI0_DAT19__UART5_CTS_B      0x30b1
  >;
};
"
Tested-by: Christoph Niedermaier <cniedermaier@dh-electronics.com>
Reviewed-by: Fabio Estevam <festevam@denx.de>
Signed-off-by: Marek Vasut <marex@denx.de>
Link: https://lore.kernel.org/r/20220929144400.13571-1-marex@denx.deSigned-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

JZ4750/55/60 (but not JZ4760b) have an optional /2 divider between the
EXT oscillator and some peripherals including UART, which will
be enabled if using a 24 MHz oscillator, and disabled when
using a 12 MHz oscillator.

This behavior relies on hardware differences: most boards (if not all)
with those SoCs have 12 or 24 MHz oscillators but many peripherals want
12Mhz to operate properly (AIC and USB-PHY at least).

The 16MHz threshold looks arbitrary but used in vendor's bootloader code
for enable the divider.

The patch doesn't affect JZ4760's behavior as it is subject for another
patchset with re-classification of all supported ingenic UARTs.

Link: https://github.com/carlos-wong/uboot_jz4755/blob/master/cpu/mips/jz_serial.c#L158Signed-off-by: Siarhei Volkau <lis8215@gmail.com>
Link: https://lore.kernel.org/r/20221031184041.1338129-3-lis8215@gmail.comSigned-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

These SoCs UART block are the same as JZ4725b' one, the difference is
outside of the block - it is in the clock generation unit (CGU).
The difference requires to make a quirk for early console init.
Acked-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
Signed-off-by: Siarhei Volkau <lis8215@gmail.com>
Link: https://lore.kernel.org/r/20221031184041.1338129-2-lis8215@gmail.comSigned-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Tweak styling of names that come directly from the code.
Suggested-by: Bagas Sanjaya <bagasdotme@gmail.com>
Reviewed-by: Bagas Sanjaya <bagasdotme@gmail.com>
Signed-off-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>
Link: https://lore.kernel.org/r/20221019093343.9546-6-ilpo.jarvinen@linux.intel.comSigned-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Use "struct serial_rs485" to get the references properly recognized.
Reviewed-by: Andy Shevchenko <andy.shevchenko@gmail.com>
Reviewed-by: Bagas Sanjaya <bagasdotme@gmail.com>
Signed-off-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>
Link: https://lore.kernel.org/r/20221019093343.9546-5-ilpo.jarvinen@linux.intel.comSigned-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Add to rs485 documentation that serial core prepares the struct
serial_rs485 when uart_get_rs485_mode() is called. Remove the wrong
claim that the driver must fill it by itself.
Reviewed-by: Andy Shevchenko <andy.shevchenko@gmail.com>
Reviewed-by: Bagas Sanjaya <bagasdotme@gmail.com>
Signed-off-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>
Link: https://lore.kernel.org/r/20221019093343.9546-4-ilpo.jarvinen@linux.intel.comSigned-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Link DT bindings reference properly.
Reviewed-by: Andy Shevchenko <andy.shevchenko@gmail.com>
Reviewed-by: Bagas Sanjaya <bagasdotme@gmail.com>
Signed-off-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>
Link: https://lore.kernel.org/r/20221019093343.9546-3-ilpo.jarvinen@linux.intel.comSigned-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Convert struct serial_rs485 comments to kernel doc format and include
it into documentation.
Suggested-by: Andy Shevchenko <andy.shevchenko@gmail.com>
Reviewed-by: Andy Shevchenko <andy.shevchenko@gmail.com>
Reviewed-by: Bagas Sanjaya <bagasdotme@gmail.com>
Signed-off-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>
Link: https://lore.kernel.org/r/20221019093343.9546-2-ilpo.jarvinen@linux.intel.comSigned-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Read the DMA status before terminating the DMA, as doing so deletes
the DMA desc.

Also, to get the correct transfer status information, pause the DMA
using dmaengine_pause() before reading the DMA status.

Fixes: e9ea096d ("serial: tegra: add serial driver")
Reviewed-by: Jon Hunter <jonathanh@nvidia.com>
Reviewed-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>
Acked-by: Thierry Reding <treding@nvidia.com>
Signed-off-by: Akhil R <akhilrajeev@nvidia.com>
Signed-off-by: Kartik <kkartik@nvidia.com>
Link: https://lore.kernel.org/r/1666105086-17326-1-git-send-email-kkartik@nvidia.comSigned-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Take advantage of the new uart_xmit_advance() helper.
Signed-off-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>
Link: https://lore.kernel.org/r/20221019091151.6692-45-ilpo.jarvinen@linux.intel.comSigned-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Take advantage of the new uart_xmit_advance() helper.
Signed-off-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>
Link: https://lore.kernel.org/r/20221019091151.6692-44-ilpo.jarvinen@linux.intel.comSigned-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Take advantage of the new uart_xmit_advance() helper.
Signed-off-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>
Link: https://lore.kernel.org/r/20221019091151.6692-43-ilpo.jarvinen@linux.intel.comSigned-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Take advantage of the new uart_xmit_advance() helper.
Signed-off-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>
Link: https://lore.kernel.org/r/20221019091151.6692-42-ilpo.jarvinen@linux.intel.comSigned-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Take advantage of the new uart_xmit_advance() helper.
Signed-off-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>
Link: https://lore.kernel.org/r/20221019091151.6692-41-ilpo.jarvinen@linux.intel.comSigned-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Take advantage of the new uart_xmit_advance() helper.
Signed-off-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>
Link: https://lore.kernel.org/r/20221019091151.6692-40-ilpo.jarvinen@linux.intel.comSigned-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Take advantage of the new uart_xmit_advance() helper.
Signed-off-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>
Link: https://lore.kernel.org/r/20221019091151.6692-39-ilpo.jarvinen@linux.intel.comSigned-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Take advantage of the new uart_xmit_advance() helper.
Signed-off-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>
Link: https://lore.kernel.org/r/20221019091151.6692-38-ilpo.jarvinen@linux.intel.comSigned-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Take advantage of the new uart_xmit_advance() helper.
Signed-off-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>
Link: https://lore.kernel.org/r/20221019091151.6692-37-ilpo.jarvinen@linux.intel.comSigned-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Take advantage of the new uart_xmit_advance() helper.
Signed-off-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>
Link: https://lore.kernel.org/r/20221019091151.6692-36-ilpo.jarvinen@linux.intel.comSigned-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Take advantage of the new uart_xmit_advance() helper.
Signed-off-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>
Link: https://lore.kernel.org/r/20221019091151.6692-35-ilpo.jarvinen@linux.intel.comSigned-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Take advantage of the new uart_xmit_advance() helper.
Reviewed-by: Baolin Wang <baolin.wang@linux.alibaba.com>
Signed-off-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>
Link: https://lore.kernel.org/r/20221019091151.6692-34-ilpo.jarvinen@linux.intel.comSigned-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Take advantage of the new uart_xmit_advance() helper.
Signed-off-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>
Link: https://lore.kernel.org/r/20221019091151.6692-33-ilpo.jarvinen@linux.intel.comSigned-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Take advantage of the new uart_xmit_advance() helper.
Reviewed-by: Thierry Reding <treding@nvidia.com>
Signed-off-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>
Link: https://lore.kernel.org/r/20221019091151.6692-32-ilpo.jarvinen@linux.intel.comSigned-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Take advantage of the new uart_xmit_advance() helper.
Signed-off-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>
Link: https://lore.kernel.org/r/20221019091151.6692-31-ilpo.jarvinen@linux.intel.comSigned-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Take advantage of the new uart_xmit_advance() helper.
Signed-off-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>
Link: https://lore.kernel.org/r/20221019091151.6692-30-ilpo.jarvinen@linux.intel.comSigned-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Take advantage of the new uart_xmit_advance() helper.
Reviewed-by: Sam Protsenko <semen.protsenko@linaro.org>
Signed-off-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>
Link: https://lore.kernel.org/r/20221019091151.6692-29-ilpo.jarvinen@linux.intel.comSigned-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Take advantage of the new uart_xmit_advance() helper.
Signed-off-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>
Link: https://lore.kernel.org/r/20221019091151.6692-28-ilpo.jarvinen@linux.intel.comSigned-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>