The work-around for the Qualcomm Datacenter Technologies QDF2400
erratum 44 sets the "qdf2400_e44_present" global variable if the
work-around is needed.  However, this check does not happen until after
earlycon is initialized, which means the work-around is not
used, and the console hangs as soon as it displays one character.

Fixes: d8a4995b ("tty: pl011: Work around QDF2400 E44 stuck BUSY bit")
Signed-off-by: NTimur Tabi <timur@codeaurora.org>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

In commit d0aeaa83 ("serial: exar:
split out the exar code from 8250_pci") the exar driver got its own
Kconfig.  However the text for the new option was never changed from
the original 8250_PCI text, and hence it appears confusing when you
get asked the same question twice:

  8250/16550 PCI device support (SERIAL_8250_PCI) [Y/n/m/?] (NEW)
    8250/16550 PCI device support (SERIAL_8250_EXAR) [Y/n/m] (NEW)

Adding to the confusion, is that there is no help text for this new
option to indicate it is specific to a certain family of cards.

Fix both issues at the same time, as well as the space vs. tab issues
introduced in the same commit.

Fixes: d0aeaa83 ("serial: exar: split out the exar code from 8250_pci")
Cc: Jiri Slaby <jslaby@suse.com>
Cc: linux-serial@vger.kernel.org
Signed-off-by: NPaul Gortmaker <paul.gortmaker@windriver.com>
Acked-by: NSudip Mukherjee <sudipm.mukherjee@gmail.com>
Reviewed-by: NAndy Shevchenko <andy.shevchenko@gmail.com>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

A side effect of 89d82324 ("tty/serial: atmel_serial: BUG: stop DMA
from transmitting in stop_tx") is that the console can be called with
TX path disabled. Then the system would hang trying to push charecters
out in atmel_console_putchar().
Signed-off-by: NNicolas Ferre <nicolas.ferre@microchip.com>
Fixes: 89d82324 ("tty/serial: atmel_serial: BUG: stop DMA from transmitting
in stop_tx")
Cc: stable <stable@vger.kernel.org>	#4.4+
Acked-by: NRichard Genoud <richard.genoud@gmail.com>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

If uart_flush_buffer() is called between atmel_tx_dma() and
atmel_complete_tx_dma(), the circular buffer has been cleared, but not
atmel_port->tx_len.
That leads to a circular buffer overflow (dumping (UART_XMIT_SIZE -
atmel_port->tx_len) bytes).
Tested-by: NNicolas Ferre <nicolas.ferre@microchip.com>
Signed-off-by: NRichard Genoud <richard.genoud@gmail.com>
Cc: stable <stable@vger.kernel.org> # 3.12+
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

The reference manual for the i.MX28 recommends to calculate the divisor
as

	divisor = (UARTCLK * 32) / baud rate, rounded to the nearest integer

, so let's do this. For a typical setup of UARTCLK = 24 MHz and baud
rate = 115200 this changes the divisor from 6666 to 6667 and so the
actual baud rate improves from 115211.521 Bd (error ≅ 0.01 %) to
115194.240 Bd (error ≅ 0.005 %).
Signed-off-by: NUwe Kleine-König <u.kleine-koenig@pengutronix.de>
Cc: stable <stable@vger.kernel.org>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

Vito Caputo reported that the sched.h split-up series
introduced a duplicate #include <linux/sched/debug.h> line
in drivers/tty/vt/keyboard.c.

Remove it.
Reported-by: NVito Caputo <vcaputo@pengaru.com>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Jiri Slaby <jslaby@suse.cz>
Cc: Alan Cox <alan@linux.intel.com>
Cc: Greg Kroah-Hartman <gregkh@suse.de>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: linux-kernel@vger.kernel.org
Signed-off-by: NIngo Molnar <mingo@kernel.org>

tty_ldisc_ref_wait() checks tty->ldisc under tty->ldisc_sem.
But if ldisc==NULL it releases them sem and reloads
tty->ldisc without holding the sem. This is wrong and
can lead to returning non-NULL ldisc without protection.

Don't reload tty->ldisc second time.
Signed-off-by: NDmitry Vyukov <dvyukov@google.com>
Cc: syzkaller@googlegroups.com
Cc: linux-kernel@vger.kernel.org
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Jiri Slaby <jslaby@suse.com>
Cc: Peter Hurley <peter@hurleysoftware.com>
Cc: One Thousand Gnomes <gnomes@lxorguk.ukuu.org.uk>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

If tty_ldisc_open() fails in tty_set_ldisc(), it tries to go back
to the old discipline or N_TTY. But that can fail as well, in such
case it panics. This is not a graceful way to handle OOM.

Leave ldisc==NULL if all attempts fail instead.
Also use existing tty_ldisc_reinit() helper function instead of
tty_ldisc_restore(). Also don't WARN/BUG in tty_ldisc_reinit()
if N_TTY fails, which would have the same net effect of bringing
kernel down on OOM. Instead print a single line message about
what has happened.
Signed-off-by: NDmitry Vyukov <dvyukov@google.com>
Cc: syzkaller@googlegroups.com
Cc: linux-kernel@vger.kernel.org
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Jiri Slaby <jslaby@suse.com>
Cc: Peter Hurley <peter@hurleysoftware.com>
Cc: One Thousand Gnomes <gnomes@lxorguk.ukuu.org.uk>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

The original patch makes the condition always true, so it is wrong.

It masks (but not fixes) the bug described in the commit message
but introduces a regression (no console is selected by SPCR)
in regular (no 'console=ttyAMA') case.

s/||/&&/ would not fix the problem as the root cause was identified
incorrectly.

This reverts commit aea9a80b.
Signed-off-by: NAleksey Makarov <aleksey.makarov@linaro.org>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>
Acked-by: NSudeep Holla <sudeep.holla@arm.com>
Tested-by: NJayachandran C <jnair@caviumnetworks.com>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

The commits mentioned below adapt the GPIO API to allow more information
to be passed directly through devm_get_gpiod_from_child() in the first
instance.  This facilitates the removal of subsequent calls, such as
gpiod_direction_output().  This patch firstly moves to utilise the new
API and secondly removes the now superfluous call do set the direction.
Reported-by: NStephen Rothwell <sfr@canb.auug.org.au>
Suggested-by: NBoris Brezillon <boris.brezillon@free-electrons.com>
Signed-off-by: NLee Jones <lee.jones@linaro.org>
[Also drop the header file dummies that only this driver was using]
Acked-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: NLinus Walleij <linus.walleij@linaro.org>

Commit 6a171b29 ("serial: 8250_dw: Allow hardware flow control to be
used") recently broke the 8250_dw driver on platforms which don't select
HAVE_CLK, as dw8250_set_termios() gets confused by the behaviour of the
fallback HAVE_CLK=n clock API in linux/clk.h which pretends everything
is fine but returns (valid) NULL clocks and 0 HZ clock rates.

That 0 rate is written into the uartclk resulting in a crash at boot,
e.g. on Cavium Octeon III based UTM-8 we get something like this:

1180000000800.serial: ttyS0 at MMIO 0x1180000000800 (irq = 41, base_baud = 25000000) is a OCTEON
------------[ cut here ]------------
WARNING: CPU: 2 PID: 1 at drivers/tty/serial/serial_core.c:441 uart_get_baud_rate+0xfc/0x1f0
...
Call Trace:
...
[<ffffffff8149c2e4>] uart_get_baud_rate+0xfc/0x1f0
[<ffffffff814a5098>] serial8250_do_set_termios+0xb0/0x440
[<ffffffff8149c710>] uart_set_options+0xe8/0x190
[<ffffffff814a6cdc>] serial8250_console_setup+0x84/0x158
[<ffffffff814a11ec>] univ8250_console_setup+0x54/0x70
[<ffffffff811901a0>] register_console+0x1c8/0x418
[<ffffffff8149f004>] uart_add_one_port+0x434/0x4b0
[<ffffffff814a1af8>] serial8250_register_8250_port+0x2d8/0x440
[<ffffffff814aa620>] dw8250_probe+0x388/0x5e8
...

The clock API is defined such that NULL is a valid clock handle so it
wouldn't be right to check explicitly for NULL. Instead treat a
clk_round_rate() return value of 0 as an error which prevents uartclk
being overwritten.

Fixes: 6a171b29 ("serial: 8250_dw: Allow hardware flow control to be used")
Signed-off-by: NJames Hogan <james.hogan@imgtec.com>
Cc: Kefeng Wang <wangkefeng.wang@huawei.com>
Cc: David Daney <david.daney@cavium.com>
Cc: Russell King <linux@armlinux.org.uk>
Cc: linux-serial@vger.kernel.org
Cc: linux-clk@vger.kernel.org
Cc: linux-mips@linux-mips.org
Cc: bcm-kernel-feedback-list@broadcom.com
Reviewed-by: NAndy Shevchenko <andy.shevchenko@gmail.com>
Reviewed-by: NJason Uy <jason.uy@broadcom.com>
Reviewed-by: NHeiko Stuebner <heiko@sntech.de>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

clk_round_rate returns a signed long and may possibly return errors
in it, for example if there is no possible rate.

Till now dw8250_set_termios ignored any error, the signednes and would
just use the value as input to clk_set_rate. This of course falls apart
if there is an actual error, so check for errors and only try to set
a rate if the value is actually valid.

This turned up on some Rockchip platforms after commit
6a171b29 ("serial: 8250_dw: Allow hardware flow control to be used")
enabled set_termios callback in all cases, not only ACPI.

Fixes: 6a171b29 ("serial: 8250_dw: Allow hardware flow control to be used")
Signed-off-by: NHeiko Stuebner <heiko@sntech.de>
Reviewed-by: NAndy Shevchenko <andy.shevchenko@gmail.com>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

If DMA is not available (even when configured in DeviceTree), the driver
will fail the startup procedure thus making serial console not
available.

For example this causes boot failure on QEMU ARMv7 (Exynos4210, SMDKC210):
    [    1.302575] OF: amba_device_add() failed (-19) for /amba/pdma@12680000
    ...
    [   11.435732] samsung-uart 13800000.serial: DMA request failed
    [   72.963893] samsung-uart 13800000.serial: DMA request failed
    [   73.143361] Kernel panic - not syncing: Attempted to kill init! exitcode=0x00000000

DMA is not necessary for serial to work, so continue with UART startup
after emitting a warning.

Fixes: 62c37eed ("serial: samsung: add dma reqest/release functions")
Cc: <stable@vger.kernel.org>
Signed-off-by: NKrzysztof Kozlowski <krzk@kernel.org>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

Currently N_HDLC line discipline uses a self-made singly linked list for
data buffers and has n_hdlc.tbuf pointer for buffer retransmitting after
an error.

The commit be10eb75
("tty: n_hdlc add buffer flushing") introduced racy access to n_hdlc.tbuf.
After tx error concurrent flush_tx_queue() and n_hdlc_send_frames() can put
one data buffer to tx_free_buf_list twice. That causes double free in
n_hdlc_release().

Let's use standard kernel linked list and get rid of n_hdlc.tbuf:
in case of tx error put current data buffer after the head of tx_buf_list.
Signed-off-by: NAlexander Popov <alex.popov@linux.com>
Cc: stable <stable@vger.kernel.org>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

sched/headers: Prepare to move the get_task_struct()/put_task_struct() and related APIs from <linux/sched.h> to <linux/sched/task.h>

But first update usage sites with the new header dependency.
Acked-by: NLinus Torvalds <torvalds@linux-foundation.org>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-kernel@vger.kernel.org
Signed-off-by: NIngo Molnar <mingo@kernel.org>

We are going to split <linux/sched/task.h> out of <linux/sched.h>, which
will have to be picked up from other headers and a couple of .c files.

Create a trivial placeholder <linux/sched/task.h> file that just
maps to <linux/sched.h> to make this patch obviously correct and
bisectable.

Include the new header in the files that are going to need it.
Acked-by: NLinus Torvalds <torvalds@linux-foundation.org>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-kernel@vger.kernel.org
Signed-off-by: NIngo Molnar <mingo@kernel.org>

We are going to split <linux/sched/debug.h> out of <linux/sched.h>, which
will have to be picked up from other headers and a couple of .c files.

Create a trivial placeholder <linux/sched/debug.h> file that just
maps to <linux/sched.h> to make this patch obviously correct and
bisectable.

Include the new header in the files that are going to need it.
Acked-by: NLinus Torvalds <torvalds@linux-foundation.org>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-kernel@vger.kernel.org
Signed-off-by: NIngo Molnar <mingo@kernel.org>

sched/headers: Prepare to move signal wakeup & sigpending methods from <linux/sched.h> into <linux/sched/signal.h>

Fix up affected files that include this signal functionality via sched.h.
Acked-by: NLinus Torvalds <torvalds@linux-foundation.org>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-kernel@vger.kernel.org
Signed-off-by: NIngo Molnar <mingo@kernel.org>

We are going to split <linux/sched/signal.h> out of <linux/sched.h>, which
will have to be picked up from other headers and a couple of .c files.

Create a trivial placeholder <linux/sched/signal.h> file that just
maps to <linux/sched.h> to make this patch obviously correct and
bisectable.

Include the new header in the files that are going to need it.
Acked-by: NLinus Torvalds <torvalds@linux-foundation.org>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-kernel@vger.kernel.org
Signed-off-by: NIngo Molnar <mingo@kernel.org>

We are going to move scheduler ABI details to <uapi/linux/sched/types.h>,
which will be used from a number of .c files.

Create empty placeholder header that maps to <linux/types.h>.

Include the new header in the files that are going to need it.
Acked-by: NLinus Torvalds <torvalds@linux-foundation.org>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-kernel@vger.kernel.org
Signed-off-by: NIngo Molnar <mingo@kernel.org>

Now that %z is standartised in C99 there is no reason to support %Z.
Unlike %L it doesn't even make format strings smaller.

Use BUILD_BUG_ON in a couple ATM drivers.

In case anyone didn't notice lib/vsprintf.o is about half of SLUB which
is in my opinion is quite an achievement.  Hopefully this patch inspires
someone else to trim vsprintf.c more.

Link: http://lkml.kernel.org/r/20170103230126.GA30170@avx2Signed-off-by: NAlexey Dobriyan <adobriyan@gmail.com>
Cc: Andy Shevchenko <andy.shevchenko@gmail.com>
Cc: Rasmus Villemoes <linux@rasmusvillemoes.dk>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Fix typos and add the following to the scripts/spelling.txt:

  comsume||consume
  comsumer||consumer
  comsuming||consuming

I see some variable names with this pattern, but this commit is only
touching comment blocks to avoid unexpected impact.

Link: http://lkml.kernel.org/r/1481573103-11329-19-git-send-email-yamada.masahiro@socionext.comSigned-off-by: NMasahiro Yamada <yamada.masahiro@socionext.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Now we can also jump to boot prom from sunhv console by sending
break twice on console for both running and panicked kernel
cases.
Signed-off-by: NVijay Kumar <vijay.ac.kumar@oracle.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

On panic, all other CPUs are stopped except the one which had
hit panic. To keep console alive, we need to migrate hvcons irq
to panicked CPU.
Signed-off-by: NVijay Kumar <vijay.ac.kumar@oracle.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

show_mem() allows to filter out node specific data which is irrelevant
to the allocation request via SHOW_MEM_FILTER_NODES.  The filtering is
done in skip_free_areas_node which skips all nodes which are not in the
mems_allowed of the current process.  This works most of the time as
expected because the nodemask shouldn't be outside of the allocating
task but there are some exceptions.  E.g.  memory hotplug might want to
request allocations from outside of the allowed nodes (see
new_node_page).

Get rid of this hardcoded behavior and push the allocation mask down the
show_mem path and use it instead of cpuset_current_mems_allowed.  NULL
nodemask is interpreted as cpuset_current_mems_allowed.

[akpm@linux-foundation.org: coding-style fixes]
Link: http://lkml.kernel.org/r/20170117091543.25850-5-mhocko@kernel.orgSigned-off-by: NMichal Hocko <mhocko@suse.com>
Acked-by: NMel Gorman <mgorman@suse.de>
Cc: Hillf Danton <hillf.zj@alibaba-inc.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: David Rientjes <rientjes@google.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

The Qualcomm Datacenter Technologies QDF2400 family of SoCs contains a
custom (non-PrimeCell) implementation of the SBSA UART. Occasionally the
BUSY bit in the Flag Register gets stuck as 1, erratum 44 for both 2432v1
and 2400v1 SoCs.Checking that the Transmit FIFO Empty (TXFE) bit is 0,
instead of checking that the BUSY bit is 1, works around the issue.

To facilitate this substitution of flags and values, introduce
vendor-specific inversion of Feature Register bits when UART AMBA Port
(UAP) data is available. For the earlycon case, prior to UAP availability,
implement alternative putc and early_write functions.

Similar to what how ARMv8 ACPI PCI quirks are detected during MCFG parsing,
check the OEM fields of the Serial Port Console Redirection (SPCR) ACPI
table to determine if the current platform is known to be affected by the
erratum.
Signed-off-by: NChristopher Covington <cov@codeaurora.org>
Acked-by: NRussell King <rmk+kernel@armlinux.org.uk>
Acked-by: NTimur Tabi <timur@codeaurora.org>
Acked-by: NMark Rutland <mark.rutland@arm.com>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

The fractional baud rate generator is available when using the
asynchronous mode of Atmel USART controllers. It makes it possible to
use higher baudrates, in exchange for a less precise clock with a
variable duty cycle.

The existing code restricts its use to the normal mode of the USART
controller, following the recommendation from the datasheet for the
first chip embedding this type of controller. This recommendation has
been removed from the documentation for the newer chips. After
verification, all revisions of this controller should be able to use the
fractional baud rate generator with the different asynchronous modes.

Removing the condition on ATMEL_US_USMODE makes it possible to get
correct baudrates at high speed in more cases.

This was tested with a board using an Atmel SAMA5D2 chip and a TI
WL1831 WiFi/Bluetooth combo chip at 3 Mbauds, with hardware flow control
enabled.
Signed-off-by: NRomain Izard <romain.izard.pro@gmail.com>
Acked-by: NLudovic Desroches <ludovic.desroches@microchip.com>
Signed-off-by: NRichard Genoud <richard.genoud@gmail.com>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

An extra "init.h" include is found in the HVC console code. As such,
the extra line is deleted.
Signed-off-by: NSergio Valverde <vlvrdv@gmail.com>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

Use pci_alloc_irq_vectors to enable MSI when available. At least the
XR17V352 supports this.
Signed-off-by: NJan Kiszka <jan.kiszka@siemens.com>
Reviewed-by: NAndy Shevchenko <andy.shevchenko@gmail.com>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

None of these registers is relevant for the userspace API.
Signed-off-by: NJan Kiszka <jan.kiszka@siemens.com>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

Became obsolete with the split-out of 8250_exar.
Signed-off-by: NJan Kiszka <jan.kiszka@siemens.com>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

Those are Exar-based, too.

With the required refactoring of the code to fit into 8250_exar, we
automatically fix the same issue pci_xr17v35x_setup had before: 8XMODE,
FCTL, TXTRG and RXTRG were always only set for port 0. Now they are
initialized for the correct target port by using port.membase.

Now we can also cleanly fix the blacklist of 8250_pci so that all
Commtech devices are rejected and 8250_exar can handle them.
Signed-off-by: NJan Kiszka <jan.kiszka@siemens.com>
Reviewed-by: NAndy Shevchenko <andy.shevchenko@gmail.com>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

So far, pci_xr17v35x_setup always initialized 8XMODE, FCTR & Co. for
port 0 because it used the address of that port instead of moving the
pointer according to the port number. Fix this and remove the unneeded
temporary ioremap by moving default_setup up and reusing the membase it
fills into the port structure.

Fixes: 14faa8cc ("tty/8250 Add support for Commtech's Fastcom Async-335 and Fastcom Async-PCIe cards")
Signed-off-by: NJan Kiszka <jan.kiszka@siemens.com>
Reviewed-by: NAndy Shevchenko <andy.shevchenko@gmail.com>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

pcim_iomap_table only returns the table of mapping, it does not perform
them. For that, we need to call pcim_iomap, but only if that mapping was
not done before.

Fixes: d0aeaa83 ("serial: exar: split out the exar code from 8250_pci")
Signed-off-by: NJan Kiszka <jan.kiszka@siemens.com>
Reviewed-by: NAndy Shevchenko <andy.shevchenko@gmail.com>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

1. Do not set the RX trigger level for software timeout devices on reset;
there is no timeout by default, and data will rot.
2. Do set the RX trigger level for hardware timeout devices when set
via sysfs attribute.

Fixes SCIFA-type serial consoles.
Signed-off-by: NUlrich Hecht <ulrich.hecht+renesas@gmail.com>
Tested-by: NGeert Uytterhoeven <geert+renesas@glider.be>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

When going to suspend, the UART registers may be lost because the power to
VDDcore is cut. This is not an issue in the normal case but when
no_console_suspend is used, we need to restore the registers in order to
get a functional console.
Signed-off-by: NAlexandre Belloni <alexandre.belloni@free-electrons.com>
Reviewed-by: NNicolas Ferre <nicolas.ferre@microchip.com>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

On a Rockchip rk3399-based board during suspend/resume testing, we
found that we could get the console UART into a state where it would
print this to the console a lot:
  serial8250: too much work for irq42

Followed eventually by:
  NMI watchdog: BUG: soft lockup - CPU#0 stuck for 11s!

Upon debugging I found that we're in this state:
  iir = 0x000000cc
  lsr = 0x00000060

It appears that somehow we have a RX Timeout interrupt but there is no
actual data present to receive.  When we're in this state the UART
driver claims that it handled the interrupt but it actually doesn't
really do anything.  This means that we keep getting the interrupt
over and over again.

Normally we don't actually need to do anything special to handle a RX
Timeout interrupt.  We'll notice that there is some data ready and
we'll read it, which will end up clearing the RX Timeout.  In this
case we have a problem specifically because we got the RX TImeout
without any data.  Reading a bogus byte is confirmed to get us out of
this state.

It's unclear how exactly the UART got into this state, but it is known
that the UART lines are essentially undriven and unpowered during
suspend, so possibly during resume some garbage / half transmitted
bits are seen on the line and put the UART into this state.

The UART on the rk3399 is a DesignWare based 8250 UART.  From mailing
list posts, it appears that other people have run into similar
problems with DesignWare based IP.  Presumably this problem is unique
to that IP, so I have placed the workaround there to avoid possibly of
accidentally triggering bad behavior on other IP.  Also note the RX
Timeout behaves very differently in the DMA case, for for now the
workaround is only applied to the non-DMA case.
Signed-off-by: NDouglas Anderson <dianders@chromium.org>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

My static checker complains that we don't have any error handling here.
It's simple enough to add it.

Fixes: bed35c6d ("serdev: add a tty port controller driver")
Signed-off-by: NDan Carpenter <dan.carpenter@oracle.com>
Acked-by: NRob Herring <robh@kernel.org>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

Fixes the following sparse warning:

drivers/tty/serial/8250/8250_pci.c:3916:6: warning:
 symbol 'pciserial_detach_ports' was not declared. Should it be static?
Signed-off-by: NWei Yongjun <weiyongjun1@huawei.com>
Reviewed-by: NAndy Shevchenko <andriy.shevchenko@linux.intel.com>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

The initial binding 'st,hw-flow-control' isn't used anywhere, in neither
in upstream nor downstream kernels.  It isn't even documented in
dt-bindings, so we can safely assume it's safe to swap to the generic
one.
Acked-by: NPeter Griffin <peter.griffin@linaro.org>
Signed-off-by: NLee Jones <lee.jones@linaro.org>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>