There is a one more step to consolidate Exar bits under 8250_exar umbrella.
This time we introduce a custom ->startup() callback where the Exar specific
settings are applied.

Cc: Robert Middleton <robert.middleton@rm5248.com>
Cc: Sudip Mukherjee <sudip.mukherjee@codethink.co.uk>
Cc: Aaron Sierra <asierra@xes-inc.com>
Signed-off-by: NAndy Shevchenko <andriy.shevchenko@linux.intel.com>
Link: https://lore.kernel.org/r/20191011115610.81507-1-andriy.shevchenko@linux.intel.comSigned-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

Add DCC earlycon support for early printks. The patch is useful for SoC
bringup where HW serial console is broken.
Signed-off-by: NMichal Simek <michal.simek@xilinx.com>
Link: https://lore.kernel.org/r/41e2920a6348e65b2e986b0e65b66531e87cd756.1570543923.git.michal.simek@xilinx.comSigned-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

When registering a serdev controller, ACPI needs to be checked for
devices attached to it. Currently, all immediate children of the ACPI
node of the controller are assumed to be UART client devices for this
controller. Furthermore, these devices are not searched elsewhere.

This is incorrect: Similar to SPI and I2C devices, the UART client
device definition (via UARTSerialBusV2) can reside anywhere in the ACPI
namespace as resource definition inside the _CRS method and points to
the controller via its ResourceSource field. This field may either
contain a fully qualified or relative path, indicating the controller
device. To address this, we need to walk over the whole ACPI namespace,
looking at each resource definition, and match the client device to the
controller via this field.

This patch is based on the existing acpi serial bus implementations in
drivers/i2c/i2c-core-acpi.c and drivers/spi/spi.c, specifically commit
4c3c5954 ("spi/acpi: enumerate all SPI
slaves in the namespace").
Signed-off-by: NMaximilian Luz <luzmaximilian@gmail.com>
Reviewed-by: NHans de Goede <hdegoede@redhat.com>
Tested-by: NHans de Goede <hdegoede@redhat.com>
Link: https://lore.kernel.org/r/20190924162226.1493407-1-luzmaximilian@gmail.comSigned-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

The sirfsoc_usp and sirfsoc_uart objects are not
used outside of the drivers/tty/serial/sirfsoc_uart.o
so make them static. Fixes following sparse warnings:

drivers/tty/serial/sirfsoc_uart.h:123:30: warning: symbol 'sirfsoc_usp' was not declared. Should it be static?
drivers/tty/serial/sirfsoc_uart.h:189:30: warning: symbol 'sirfsoc_uart' was not declared. Should it be static?
Signed-off-by: NBen Dooks <ben.dooks@codethink.co.uk>
Link: https://lore.kernel.org/r/20191009135356.11180-1-ben.dooks@codethink.co.ukSigned-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

Add system wakeup capability over UART RX line for wakeup capable UART.
When system is suspended, RX line act as an interrupt to wakeup system
for any communication requests from peer.
Signed-off-by: NAkash Asthana <akashast@codeaurora.org>
Link: https://lore.kernel.org/r/1570700803-17566-1-git-send-email-akashast@codeaurora.orgSigned-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

Move ISR registration from startup to probe function to avoid registering
it everytime when the port open is called for driver.
Signed-off-by: NAkash Asthana <akashast@codeaurora.org>
Link: https://lore.kernel.org/r/1570700763-17319-1-git-send-email-akashast@codeaurora.orgSigned-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

All i.MX SoCs except i.MX1 have ONLY one necessary IRQ, use
platform_get_irq_optional() to get second/third IRQ which are
optional to avoid below error message during probe:

[    0.726219] imx-uart 30860000.serial: IRQ index 1 not found
[    0.731329] imx-uart 30860000.serial: IRQ index 2 not found

Fixes: 7723f4c5 ("driver core: platform: Add an error message to platform_get_irq*()")
Signed-off-by: NAnson Huang <Anson.Huang@nxp.com>
Link: https://lore.kernel.org/r/1570614559-11900-1-git-send-email-Anson.Huang@nxp.comSigned-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

Fix Sphinx warning in serial_core.c:

../drivers/tty/serial/serial_core.c:1969: WARNING: Definition list ends without a blank line; unexpected unindent.

Fixes: 73abaf87 ("serial: earlycon: Refactor parse_options into serial core")
Signed-off-by: NRandy Dunlap <rdunlap@infradead.org>
Cc: Peter Hurley <peter@hurleysoftware.com>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Link: https://lore.kernel.org/r/e989641c-224a-1090-e596-e7cc800bed44@infradead.orgSigned-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

There are two checks to see if the manual gpio is configured, but
these the check is seeing if the structure is NULL instead it
should check to see if there are CTS and/or RTS pins defined.

This patch uses checks for those individual pins instead of
checking for the structure itself to restore auto RTS/CTS.
Signed-off-by: NAdam Ford <aford173@gmail.com>
Reviewed-by: NYegor Yefremov <yegorslists@googlemail.com>
Link: https://lore.kernel.org/r/20191006163314.23191-2-aford173@gmail.comSigned-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

When using mctrl_gpio_to_gpiod, it dereferences gpios into a single
requested GPIO.  This dereferencing can break if gpios is NULL,
so this patch adds a NULL check before dereferencing it.  If
gpios is NULL, this function will also return NULL.
Signed-off-by: NAdam Ford <aford173@gmail.com>
Reviewed-by: NYegor Yefremov <yegorslists@googlemail.com>
Link: https://lore.kernel.org/r/20191006163314.23191-1-aford173@gmail.comSigned-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

Fix incorrect read-modify-write sequence in lpuart_flush_buffer() that
was reading from UARTPFIFO and writing to UARTCFIFO instead of
operating solely on the latter.

Fixes: 9bc19af9 ("tty: serial: fsl_lpuart: Flush HW FIFOs in .flush_buffer")
Signed-off-by: NAndrey Smirnov <andrew.smirnov@gmail.com>
Reported-by: NVivien Didelot <vivien.didelot@gmail.com>
Tested-by: NVivien Didelot <vivien.didelot@gmail.com>
Tested-by: NAndrew Lunn <andrew@lunn.ch>
Reviewed-by: NFabio Estevam <festevam@gmail.com>
Cc: Stefan Agner <stefan@agner.ch>
Cc: Chris Healy <cphealy@gmail.com>
Cc: Cory Tusar <cory.tusar@zii.aero>
Cc: Lucas Stach <l.stach@pengutronix.de>
Cc: Jiri Slaby <jslaby@suse.com>
Link: https://lore.kernel.org/r/20191004215537.5308-1-andrew.smirnov@gmail.comSigned-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

Fix tty driver build on SPARC by not using __exitdata.
It appears that SPARC does not support section .exit.data.

Fixes these build errors:

`.exit.data' referenced in section `.exit.text' of drivers/tty/n_hdlc.o: defined in discarded section `.exit.data' of drivers/tty/n_hdlc.o
`.exit.data' referenced in section `.exit.text' of drivers/tty/n_hdlc.o: defined in discarded section `.exit.data' of drivers/tty/n_hdlc.o
`.exit.data' referenced in section `.exit.text' of drivers/tty/n_hdlc.o: defined in discarded section `.exit.data' of drivers/tty/n_hdlc.o
`.exit.data' referenced in section `.exit.text' of drivers/tty/n_hdlc.o: defined in discarded section `.exit.data' of drivers/tty/n_hdlc.o
Reported-by: Nkbuild test robot <lkp@intel.com>
Fixes: 06324664 ("format-security: move static strings to const")
Signed-off-by: NRandy Dunlap <rdunlap@infradead.org>
Cc: Kees Cook <keescook@chromium.org>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: "David S. Miller" <davem@davemloft.net>
Cc: Andrew Morton <akpm@linux-foundation.org>
Link: https://lore.kernel.org/r/675e7bd9-955b-3ff3-1101-a973b58b5b75@infradead.orgSigned-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

There are two parts which should be fixed. The first one is to assigned
uartps_major at the end of probe() to avoid complicated logic when
something fails.
The second part is initialized uartps_major number to 0 when last device is
removed. This will ensure that on next probe driver will ask for new
dynamic major number.

Fixes: ab262666 ("serial: uartps: Use the same dynamic major number for all ports")
Reported-by: NPaul Thomas <pthomas8589@gmail.com>
Cc: stable <stable@vger.kernel.org>
Signed-off-by: NMichal Simek <michal.simek@xilinx.com>
Link: https://lore.kernel.org/r/d2652cda992833315c4f96f06953eb547f928918.1570194248.git.michal.simek@xilinx.comSigned-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

According to the comment of tty_port_destroy():
    When a port was initialized using tty_port_init, one has to destroy
    the port by tty_port_destroy();

tty_port_init() is called in gsm_dlci_alloc()
so tty_port_destroy() needs to be called in gsm_dlci_free()
Signed-off-by: NXiaoming Ni <nixiaoming@huawei.com>
Link: https://lore.kernel.org/r/1569317156-45850-1-git-send-email-nixiaoming@huawei.comSigned-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

We have got existing macro to check for CONFIG option, use it.
Signed-off-by: NPavel Machek <pavel@denx.de>

Link: https://lore.kernel.org/r/20190924083244.GA4344@amdSigned-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

Make the SIRQ polarity for Aspeed AST24xx/25xx VUART configurable via
sysfs. This setting need to be changed on specific host platforms
depending on the selected host interface (LPC / eSPI).

The setting is configurable via sysfs rather than device-tree to stay in
line with other related configurable settings.

On AST2500 the VUART SIRQ polarity can be auto-configured by reading a
bit from a configuration register, e.g. the LPC/eSPI interface
configuration bit.

Tested: Verified on TYAN S7106 mainboard.
Signed-off-by: NOskar Senft <osk@google.com>
Link: https://lore.kernel.org/r/20190905144130.220713-1-osk@google.comSigned-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

Call uart_unregister_driver() conditionally instead of
unconditionally, only if it has been previously registered.

This uses driver.state, just as the sh-sci.c driver does.

Fixes this null pointer dereference in tty_unregister_driver(),
since the 'driver' argument is null:

  general protection fault: 0000 [#1] PREEMPT SMP KASAN PTI
  RIP: 0010:tty_unregister_driver+0x25/0x1d0

Fixes: 238b8721 ("[PATCH] serial uartlite driver")
Signed-off-by: NRandy Dunlap <rdunlap@infradead.org>
Cc: stable <stable@vger.kernel.org>
Cc: Peter Korsgaard <jacmet@sunsite.dk>
Link: https://lore.kernel.org/r/9c8e6581-6fcc-a595-0897-4d90f5d710df@infradead.orgSigned-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

Following an incorrect indentation reported to me by Dan Carpenter, I
noticed that the SysRq lines were inherited from the lpuart driver[1] (note
how the 'continue' is aligned to 'sport->port.sysrq = 0') and we have never
actually tested the SysRq support.

'sport->sysrq = 0' is not necessary neither before nor after 'continue',
because sysrq will already be 0 after uart_handle_sysrq_char() will finish.
Also, since the LINFlexD driver never called uart_handle_break(), sysrq
would have never been set to a nonzero value, so uart_handle_sysrq_char()
was not going to do anything.

Break conditions are detected based on a null data byte along with a
framing error (stop bit sampled to 0).

[1] https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/drivers/tty/serial/fsl_lpuart.c?h=b3e3bf2ef2c74f5ce5c19510edbbb9bfc1d249c2#n659

Fixes: 09864c1c ("tty: serial: Add linflexuart driver for S32V234")
Signed-off-by: NStefan-Gabriel Mirea <stefan-gabriel.mirea@nxp.com>
Reported-by: Nkbuild test robot <lkp@intel.com>
Reported-by: NDan Carpenter <dan.carpenter@oracle.com>
Link: https://lore.kernel.org/r/20190918184439.7465-1-stefan-gabriel.mirea@nxp.comSigned-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

As platform_get_irq() now prints an error when the interrupt does not
exist, scary warnings may be printed for optional interrupts:

    sh-sci e6550000.serial: IRQ index 1 not found
    sh-sci e6550000.serial: IRQ index 2 not found
    sh-sci e6550000.serial: IRQ index 3 not found
    sh-sci e6550000.serial: IRQ index 4 not found
    sh-sci e6550000.serial: IRQ index 5 not found

Fix this by calling platform_get_irq_optional() instead for all but the
first interrupts, which are optional.

Fixes: 7723f4c5 ("driver core: platform: Add an error message to platform_get_irq*()")
Signed-off-by: NGeert Uytterhoeven <geert+renesas@glider.be>
Reviewed-by: NStephen Boyd <swboyd@chromium.org>
Reviewed-by: NYoshihiro Shimoda <yoshihiro.shimoda.uh@renesas.com>
Tested-by: NYoshihiro Shimoda <yoshihiro.shimoda.uh@renesas.com>
Link: https://lore.kernel.org/r/20191001180743.1041-1-geert+renesas@glider.beSigned-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

The sifive serial driver implements earlycon support, but unless
another driver is built in that supports earlycon support it won't
be usable.  Explicitly select SERIAL_EARLYCON instead.
Signed-off-by: NChristoph Hellwig <hch@lst.de>
Reviewed-by: NPaul Walmsley <paul.walmsley@sifive.com>
Link: https://lore.kernel.org/r/20190910055923.28384-1-hch@lst.deSigned-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

'exit' functions should be marked as __exit, not __init.

Fixes: c10b1332 ("tty: serial: Add RDA8810PL UART driver")
Signed-off-by: NChristophe JAILLET <christophe.jaillet@wanadoo.fr>
Link: https://lore.kernel.org/r/20190910041702.7357-1-christophe.jaillet@wanadoo.frSigned-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

'exit' functions should be marked as __exit, not __init.

Fixes: fc60a8b6 ("tty: serial: owl: Implement console driver")
Signed-off-by: NChristophe JAILLET <christophe.jaillet@wanadoo.fr>
Link: https://lore.kernel.org/r/20190910041129.6978-1-christophe.jaillet@wanadoo.frSigned-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

Simplify the code which fetches the input clock by using
devm_clk_get_optional(). This comes with a small functional change: previously
all errors were ignored except deferred probe. Now all errors are
treated as errors. If no input clock is present devm_clk_get_optional() will
return NULL instead of an error which matches the behavior of the old code.
Signed-off-by: NAndy Shevchenko <andriy.shevchenko@linux.intel.com>
Link: https://lore.kernel.org/r/20190925162617.30368-1-andriy.shevchenko@linux.intel.comSigned-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

Some devices support MSI interrupts. Let's at least try to use them in
platforms that provide MSI capability.

While at that, remove the now duplicated code from qrp_serial_setup().
Signed-off-by: NFelipe Balbi <felipe.balbi@linux.intel.com>
Link: https://lore.kernel.org/r/20191001115825.795700-1-felipe.balbi@linux.intel.comSigned-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

pl011_dma_probe() is only used in pl011_dma_startup() which does only
exist when CONFIG_DMA_ENGINE=y, so remove the unused dummy version to
silence the warning.
Signed-off-by: NQian Cai <cai@lca.pw>
Link: https://lore.kernel.org/r/1568726340-4518-1-git-send-email-cai@lca.pwSigned-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

The reason for this patch is xilinx_uartps driver which create one dynamic
instance per IP with unique major and minor combinations. drv->nr is in
this case all the time setup to 1. That means that uport->line is all the
time setup to 0 and drv->tty_driver->name_base is doing shift in name to
for example ttyPS3.

register_console() is looping over console_cmdline array and looking for
proper name/index combination which is in our case ttyPS/3.
That's why every instance of driver needs to be registered with proper
combination of name/number (ttyPS/3). Using uport->line is doing
registration with ttyPS/0 which is wrong that's why proper console index
should be used which is in cons->index field.

Also it is visible that recording console should be done based on
information about console not about the port but in most cases numbers are
the same and xilinx_uartps is only one exception now.
Signed-off-by: NMichal Simek <michal.simek@xilinx.com>
Link: https://lore.kernel.org/r/4a877f1c7189a7c45b59a6ebfc3de607e8758949.1567434470.git.michal.simek@xilinx.comSigned-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

Use software emulated RS485 direction control to provide RS485 API

Currently it is not possible to use rs485 as pointer to
rs485_config struct in struct uart_port is NULL in case we
configure the port through device tree.
Signed-off-by: NHeiko Schocher <hs@denx.de>

Link: https://lore.kernel.org/r/20190913050105.1132080-1-hs@denx.deSigned-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

In order to access the UART without the interrupts, the kernel uses
the basic polling methods for IO with the device. With these methods
implemented, it is now possible to enable kgdb during early boot over serial.
Signed-off-by: NLanqing Liu <liuhhome@gmail.com>
Reviewed-by: NBaolin Wang <baolin.wang@linaro.org>
Tested-by: NBaolin Wang <baolin.wang@linaro.org>
Link: https://lore.kernel.org/r/f112a741c053ac5fb0637e2f058be81e17f78ccc.1568862391.git.liuhhome@gmail.comSigned-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

Using only 4 DMA periods for UART RX is very few if we have a high
frequency of small transfers - like in our case using Bluetooth with
many small packets via UART - causing many dma transfers but in each
only filling a fraction of a single buffer. Such a case may lead to
the situation that DMA RX transfer is triggered but no free buffer is
available. When this happens dma channel ist stopped - with the patch
"dmaengine: imx-sdma: fix dma freezes" temporarily only - with the
possible consequences that:
with disabled hw flow control:
  If enough data is incoming on UART port the RX FIFO runs over and
  characters will be lost. What then happens depends on upper layer.

with enabled hw flow control:
  If enough data is incoming on UART port the RX FIFO reaches a level
  where CTS is deasserted and remote device sending the data stops.
  If it fails to stop timely the i.MX' RX FIFO may run over and data
  get lost. Otherwise it's internal TX buffer may getting filled to
  a point where it runs over and data is again lost. It depends on
  the remote device how this case is handled and if it is recoverable.

Obviously we want to avoid having no free buffers available. So we
decrease the size of the buffers and increase their number and the
total buffer size.
Signed-off-by: NPhilipp Puschmann <philipp.puschmann@emlix.com>
Reviewed-by: NLucas Stach <l.stach@pengutronix.de>
Link: https://lore.kernel.org/r/20190923135916.1212-1-philipp.puschmann@emlix.comSigned-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

Add PIO mode support in receive and transmit path with RX interrupt
trigger of 16 bytes for Tegra194 and older chips.
Signed-off-by: NShardar Shariff Md <smohammed@nvidia.com>
Signed-off-by: NKrishna Yarlagadda <kyarlagadda@nvidia.com>
Link: https://lore.kernel.org/r/1567572187-29820-13-git-send-email-kyarlagadda@nvidia.comSigned-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

Standard UART controllers support +/-4% baud rate error tolerance.
Tegra186 only supports 0% to +4% error tolerance whereas other Tegra
chips support standard +/-4% rate. Add chip data for knowing error
tolerance level for each soc. Creating new compatible for Tegra194
chip as it supports baud rate error tolerance of -2 to +2%, different
from older chips.
Signed-off-by: NShardar Shariff Md <smohammed@nvidia.com>
Signed-off-by: NKrishna Yarlagadda <kyarlagadda@nvidia.com>
Link: https://lore.kernel.org/r/1567572187-29820-12-git-send-email-kyarlagadda@nvidia.comSigned-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

Add support to adjust baud rates to fall under supported tolerance
range through DT.

Tegra186 chip has a hardware issue resulting in frame errors when
tolerance level for baud rate is negative. Provided entries to adjust
baud rate to be within acceptable range and work with devices that
can send negative baud rate. Also report error when baud rate set is
out of tolerance range of controller updated in device tree.
Signed-off-by: NShardar Shariff Md <smohammed@nvidia.com>
Signed-off-by: NKrishna Yarlagadda <kyarlagadda@nvidia.com>
Link: https://lore.kernel.org/r/1567572187-29820-11-git-send-email-kyarlagadda@nvidia.comSigned-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

Add support to use 8 bytes trigger for Tegra186 SOC.
Signed-off-by: NShardar Shariff Md <smohammed@nvidia.com>
Signed-off-by: NKrishna Yarlagadda <kyarlagadda@nvidia.com>
Link: https://lore.kernel.org/r/1567572187-29820-9-git-send-email-kyarlagadda@nvidia.comSigned-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

Set maximum number of UART ports to 8 as older chips have 5 ports and
Tergra186 and later chips will have 8 ports. Add this info to chip
data. Read device tree compatible of this driver and register uart
driver with max ports of matching chip data.
Signed-off-by: NShardar Shariff Md <smohammed@nvidia.com>
Signed-off-by: NKrishna Yarlagadda <kyarlagadda@nvidia.com>
Link: https://lore.kernel.org/r/1567572187-29820-8-git-send-email-kyarlagadda@nvidia.comSigned-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

Chips prior to Tegra186 needed delay of 3 UART clock cycles to avoid
data loss. This issue is fixed in Tegra186 and a new flag is added to
check if FIFO mode is enabled. chip data updated to check if this flag
is available for a chip. Tegra186 has new compatible to enable this
flag.
Signed-off-by: NShardar Shariff Md <smohammed@nvidia.com>
Signed-off-by: NKrishna Yarlagadda <kyarlagadda@nvidia.com>
Link: https://lore.kernel.org/r/1567572187-29820-7-git-send-email-kyarlagadda@nvidia.comSigned-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

Report overrun/parity/frame/break errors to top tty layer. Add support
to ignore break character if IGNBRK is set.
Signed-off-by: NShardar Shariff Md <smohammed@nvidia.com>
Signed-off-by: NKrishna Yarlagadda <kyarlagadda@nvidia.com>
Link: https://lore.kernel.org/r/1567572187-29820-5-git-send-email-kyarlagadda@nvidia.comSigned-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

FIFO reset/flush code implemented now does not follow programming
guidelines. RTS line has to be turned off while flushing FIFOs to
avoid new transfers. Also check LSR bits UART_LSR_TEMT and UART_LSR_DR
to confirm FIFOs are flushed.
Signed-off-by: NShardar Shariff Md <smohammed@nvidia.com>
Signed-off-by: NKrishna Yarlagadda <kyarlagadda@nvidia.com>
Link: https://lore.kernel.org/r/1567572187-29820-4-git-send-email-kyarlagadda@nvidia.comSigned-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

This avoids two race conditions from the UART shutdown sequence both
leading to 'Machine check error in AXI2APB' and kernel oops.

One was that the clock was disabled before the DMA was terminated making
it possible for the DMA callbacks to be called after the clock was
disabled. These callbacks could write to the UART registers causing
timeout.

The second was that the clock was disabled before the UART was
completely flagged as closed. This is done after the shutdown is called
and a new write could be started after the clock was disabled.
tegra_uart_start_pio_tx could be called causing timeout.

Given that the baud rate is reset at the end of shutdown sequence, this
fix is to examine the baud rate to avoid register access from both race
conditions.

Besides, terminate the DMA before disabling the clock.
Signed-off-by: NAhung Cheng <ahcheng@nvidia.com>
Signed-off-by: NShardar Mohammed <smohammed@nvidia.com>
Signed-off-by: NKrishna Yarlagadda <kyarlagadda@nvidia.com>
Link: https://lore.kernel.org/r/1567572187-29820-3-git-send-email-kyarlagadda@nvidia.comSigned-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

Add support to ignore read characters if CREAD flag is not set.
Signed-off-by: NShardar Shariff Md <smohammed@nvidia.com>
Signed-off-by: NKrishna Yarlagadda <kyarlagadda@nvidia.com>
Link: https://lore.kernel.org/r/1567572187-29820-2-git-send-email-kyarlagadda@nvidia.comSigned-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

The sequence of arguments which was passed to handle_lsr_errors() didn't
match the parameters defined in that function, &lsr was passed to flag
and &flag was passed to lsr, this patch fixed that.

Fixes: b7396a38 ("tty/serial: Add Spreadtrum sc9836-uart driver support")
Signed-off-by: NChunyan Zhang <chunyan.zhang@unisoc.com>
Signed-off-by: NChunyan Zhang <zhang.lyra@gmail.com>
Cc: stable <stable@vger.kernel.org>
Link: https://lore.kernel.org/r/20190905074151.5268-1-zhang.lyra@gmail.comSigned-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>