The SC16IS752 has an Enhanced Feature Register which is aliased at the
same address as the Interrupt Identification Register; accessing it
requires that a magic value is written to the Line Configuration
Register. If an interrupt is raised while the EFR is mapped in then
the ISR won't be able to access the IIR, leading to the "Unexpected
interrupt" error messages.

Avoid the problem by claiming a mutex around accesses to the EFR
register, also claiming the mutex in the interrupt handler work
item (this is equivalent to disabling interrupts to interlock against
a non-threaded interrupt handler).

See: https://github.com/raspberrypi/linux/issues/2529Signed-off-by: Phil Elwell <phil@raspberrypi.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

The SC16IS752 is a dual-channel device. The two channels are largely
independent, but the IRQ signals are wired together as an open-drain,
active low signal which will be driven low while either of the
channels requires attention, which can be for significant periods of
time until operations complete and the interrupt can be acknowledged.
In that respect it is should be treated as a true level-sensitive IRQ.

The kernel, however, needs to be able to exit interrupt context in
order to use I2C or SPI to access the device registers (which may
involve sleeping).  Therefore the interrupt needs to be masked out or
paused in some way.

The usual way to manage sleeping from within an interrupt handler
is to use a threaded interrupt handler - a regular interrupt routine
does the minimum amount of work needed to triage the interrupt before
waking the interrupt service thread. If the threaded IRQ is marked as
IRQF_ONESHOT the kernel will automatically mask out the interrupt
until the thread runs to completion. The sc16is7xx driver used to
use a threaded IRQ, but a patch switched to using a kthread_worker
in order to set realtime priorities on the handler thread and for
other optimisations. The end result is non-threaded IRQ that
schedules some work then returns IRQ_HANDLED, making the kernel
think that all IRQ processing has completed.

The work-around to prevent a constant stream of interrupts is to
mark the interrupt as edge-sensitive rather than level-sensitive,
but interpreting an active-low source as a falling-edge source
requires care to prevent a total cessation of interrupts. Whereas
an edge-triggering source will generate a new edge for every interrupt
condition a level-triggering source will keep the signal at the
interrupting level until it no longer requires attention; in other
words, the host won't see another edge until all interrupt conditions
are cleared. It is therefore vital that the interrupt handler does not
exit with an outstanding interrupt condition, otherwise the kernel
will not receive another interrupt unless some other operation causes
the interrupt state on the device to be cleared.

The existing sc16is7xx driver has a very simple interrupt "thread"
(kthread_work job) that processes interrupts on each channel in turn
until there are no more. If both channels are active and the first
channel starts interrupting while the handler for the second channel
is running then it will not be detected and an IRQ stall ensues. This
could be handled easily if there was a shared IRQ status register, or
a convenient way to determine if the IRQ had been deasserted for any
length of time, but both appear to be lacking.

Avoid this problem (or at least make it much less likely to happen)
by reducing the granularity of per-channel interrupt processing
to one condition per iteration, only exiting the overall loop when
both channels are no longer interrupting.
Signed-off-by: Phil Elwell <phil@raspberrypi.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

The 8250 FIFOs indeed need to be cleared after stopping transmission in
RS485 mode without SER_RS485_RX_DURING_TX flag set. But there are two
problems with the approach taken by the previous patch from Fixes tag.

First, serial8250_clear_fifos() should clear fifos, but what it really
does is it enables the FIFOs unconditionally if present, clears them
and then sets the FCR register to zero, which effectively disables the
FIFOs. In case the FIFO is disabled, enabling it and clearing it makes
no sense and in fact can trigger misbehavior of the 8250 core. Moreover,
the FCR register may contain other FIFO configuration bits which may not
be writable unconditionally and writing them incorrectly can trigger
misbehavior of the 8250 core too. (ie. AM335x UART swallows the first
byte and retransmits the last byte twice because of this FCR write).

Second, serial8250_clear_and_reinit_fifos() completely reloads the FCR,
but what really has to happen at the end of the RS485 transmission is
clearing of the FIFOs and nothing else.

This patch repairs serial8250_clear_fifos() so that it really only
clears the FIFOs by operating on FCR[2:1] bits and leaves all the
other bits alone. It also undoes serial8250_clear_and_reinit_fifos()
from __do_stop_tx_rs485() as serial8250_clear_fifos() is sufficient.
Signed-off-by: Marek Vasut <marex@denx.de>
Fixes: 2bed8a8e ("Clearing FIFOs in RS485 emulation mode causes subsequent transmits to break")
Cc: Daniel Jedrychowski <avistel@gmail.com>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: stable <stable@vger.kernel.org> # let it bake a bit before merging
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

In preparation to remove the node name pointer from struct device_node,
convert printf users to use the %pOFn format specifier.

Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Jiri Slaby <jslaby@suse.com>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: linux-serial@vger.kernel.org
Cc: linuxppc-dev@lists.ozlabs.org
Signed-off-by: Rob Herring <robh@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

In commit c58caaab ("serial: 8250: of: Defer probe on missing IRQ"), a
check was added for the UART driver being probed prior to the parent IRQ
controller.

Unfortunately this breaks certain boards which have no interrupt support,
like Huawei D03.

Indeed, the 8250 DT bindings state that interrupts should be supported -
not must.

To fix, switch from irq_of_parse_and_map() to of_irq_get(), which
does relay whether the IRQ host controller domain is not ready, i.e.
defer probe, instead of assuming it.

Fixes: c58caaab ("serial: 8250: of: Defer probe on missing IRQ")
Signed-off-by: John Garry <john.garry@huawei.com>
Reviewed-by: Rob Herring <robh@kernel.org>
Reviewed-by: Alexander Sverdlin <alexander.sverdlin@nokia.com>
Tested-by: Alexander Sverdlin <alexander.sverdlin@nokia.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

If you've got the "console" serial port setup to use just as a UART
(AKA there is no "console=ttyMSMX" on the kernel command line) then
certain initialization is skipped.  When userspace later tries to do
something with the port then things go boom (specifically, on my
system, some sort of exception hit that caused the system to reboot
itself w/ no error messages).

Let's cleanup / refactor the init so that we always run the same init
code regardless of whether we're using the console.

To make this work, we make rely on qcom_geni_serial_pm doing its job
to turn resources on.

For the record, here is a trace of the order of things (after this
patch) when console= is specified on the command line and we have an
agetty on the port:
  qcom_geni_serial_pm: 4 (undefined) => 0 (on)
  qcom_geni_console_setup
  qcom_geni_serial_port_setup
  qcom_geni_serial_console_write
  qcom_geni_serial_startup
  qcom_geni_serial_start_tx

...and here is the order of things (after this patch) when console= is
_NOT_ specified on the command line and we have an agetty port:
  qcom_geni_serial_pm: 4 => 0
  qcom_geni_serial_pm: 0 => 3
  qcom_geni_serial_pm: 3 => 0
  qcom_geni_serial_startup
  qcom_geni_serial_port_setup
  qcom_geni_serial_pm: 0 => 3
  qcom_geni_serial_pm: 3 => 0
  qcom_geni_serial_startup
  qcom_geni_serial_start_tx

Fixes: c4f52879 ("tty: serial: msm_geni_serial: Add serial driver support for GENI based QUP")
Signed-off-by: Douglas Anderson <dianders@chromium.org>
Reviewed-by: Matthias Kaehlcke <mka@chromium.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

With gcc 4.1.2:

    drivers/tty/serial/qcom_geni_serial.c: In function ‘qcom_geni_serial_probe’:
    drivers/tty/serial/qcom_geni_serial.c:1261: warning: ‘drv’ may be used uninitialized in this function

Indeed, if dev.of_node is NULL, drv will be used uninitialized, and
dereferenced in uart_add_one_port().  However, as this driver supports
DT only, dev.of_node will always be valid.

Hence remove the useless check for dev.of_node, killing the warning as a
side effect.

Fixes: 8a8a66a1 ("tty: serial: qcom_geni_serial: Add support for flow control")
Signed-off-by: Geert Uytterhoeven <geert@linux-m68k.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

On the error path of mxs_auart_request_gpio_irq() is performed
backward iterating with index i of enum type. Underline enum type
may be unsigned char. In this case check (--i >= 0) will be always
true and error handling goes into infinite loop.

The patch changes the check so that it is valid for signed and unsigned
types.

Found by Linux Driver Verification project (linuxtesting.org).
Signed-off-by: Anton Vasilyev <vasilyev@ispras.ru>
Acked-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Make the macros' definition and code have the same correct indentation.
Signed-off-by: Baolin Wang <baolin.wang@linaro.org>
Acked-by: Chunyan Zhang <chunyan.zhang@spreadtrum.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

The register offset value should be 'unsigned int' type.

Moreover, prefer 'unsigned int' to bare use of 'unsigned'.
Signed-off-by: Baolin Wang <baolin.wang@linaro.org>
Acked-by: Chunyan Zhang <chunyan.zhang@spreadtrum.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

The devm_ioremap_resource() will valid the resources, thus remove the
unnecessary resource validation in the driver.
Signed-off-by: Baolin Wang <baolin.wang@linaro.org>
Acked-by: Chunyan Zhang <chunyan.zhang@spreadtrum.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Define readable macros instead of magic number to make code more readable.
Signed-off-by: Baolin Wang <baolin.wang@linaro.org>
Acked-by: Chunyan Zhang <chunyan.zhang@spreadtrum.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Remove the unused reg_backup structure.
Signed-off-by: Baolin Wang <baolin.wang@linaro.org>
Acked-by: Chunyan Zhang <chunyan.zhang@spreadtrum.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Allow 8250 omap serial driver to be used for K3 platforms.
Signed-off-by: Lokesh Vutla <lokeshvutla@ti.com>
Signed-off-by: Nishanth Menon <nm@ti.com>
Acked-by: Tony Lindgren <tony@atomide.com>
Acked-by: Vignesh R <vigneshr@ti.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Ensure that the baud clock is also enabled for UART register writes in
driver resume. On Exynos5433 SoC this is needed to avoid external abort
issue.
Signed-off-by: Marek Szyprowski <m.szyprowski@samsung.com>
Reviewed-by: Krzysztof Kozlowski <krzk@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Since the register offsets are different for RZ/A2 SCIF, we need
to declare a separate string for it.
Signed-off-by: Chris Brandt <chris.brandt@renesas.com>
Reviewed-by: Geert Uytterhoeven <geert+renesas@glider.be>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

This reverts commit 2d4dd0da.

This broke earlycon on all Renesas ARM platforms using a SCIF port for the
serial console (R-Car, RZ/A1, RZ/G1, RZ/G2 SoCs), due to an incorrect value
of port->regshift.
Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
Acked-by: Chris Brandt <chris.brandt@renesas.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

This reverts commit 7acece71.
Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
Acked-by: Chris Brandt <chris.brandt@renesas.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

On some i.MX SoCs' low power mode, such as i.MX7D's LPSR(low power
state retention), UART iomux settings will be lost, need to add
pinctrl sleep/default mode switch during suspend/resume to make
sure UART iomux settings are correct after resume.
Signed-off-by: Anson Huang <Anson.Huang@nxp.com>
Acked-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

In noirq suspend/resume stage with no_console_suspend enabled,
imx_uart_console_write() may be called to print out log_buf
message by printk(), so there will be race condition between
imx_uart_console_write() and imx_uart_save/restore_context(),
need to add lock to protect the registers save/restore operations.
Signed-off-by: Anson Huang <Anson.Huang@nxp.com>
Acked-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Before the program enters the uart ISR, the local interrupt has been
disabled by the system, so it's not appropriate to use spin_lock_irqsave
interface in the ISR.
Signed-off-by: jun qian <hangdianqj@163.com>
Reviewed-by: Barry Song <21cnbao@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Driver console functions are using pointer to static array with fixed
size. There can be only one serial console at the time which is found
by register_console(). register_console() is filling cons->index to
port->line value.
Signed-off-by: Shubhrajyoti Datta <shubhrajyoti.datta@xilinx.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

register_console is called twice once from

uart_add_one_port -> uart_configure_port
remove the double call
Signed-off-by: Shubhrajyoti Datta <shubhrajyoti.datta@xilinx.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Move uart register to probe.
This is in preparation of removing the hardcoding of number of uarts.
Signed-off-by: Shubhrajyoti Datta <shubhrajyoti.datta@xilinx.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

At probe the uartlite is getting configured.
Enable the clocks before assiging uart and
disable after probe is done.
Signed-off-by: Shubhrajyoti Datta <shubhrajyoti.datta@xilinx.com>
Signed-off-by: Michal Simek <michal.simek@xilinx.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

The printk() in serial8250_interrupt() was once hidden behind a debug
macro in commit f4f653e9 ("serial: 8250, disable "too much work"
messages") and reverted back in commit 12de375e ("Revert "serial:
8250, disable "too much work" messages"").

This was introduced first in 0.99.13k with the "serial" driver itself
(and called pass_number with a limit of 64 and no print). In 1.1.13 it
was renamed to pass_counter and the printk was behind #if 0. In 1.1.94
the limit of 64 was increased to 256 and hidden behind
RS_ISR_PASS_LIMIT. With this change the #if 0 turned into #if 1. It
slowly become what we have today with a loop limit of 512.

Usually, that printk isn't hit. However on KVM with a busy UART and
overloaded host it might happen. It is also likely with threaded
interrupts and a task which preempts the interrupt handler.

If the UART has (legitimate) work to do and we break out of the loop,
nothing changes: the interrupt is most likely already pending in the
interrupt controller and we end up in the handler anyway. This printk is
hardly helping.

Older kernels also had a comment saying that a bad configuration might
lead to this but I don't see how that should happen because a wrongly
configured interrupt number would let the handler leave "early" with
IRQ_NONE and the spurious detected will handle that (weill since 2.6.11,
before that we had no spurious detector). In that case, we would never
loop that often here.

This loop looks like an optimisation in order to pull the bytes from the
FIFO which were received while we were already here instead of waiting
for the interrupt. This might have been a good idea while the CPUs were
slow and FIFOs small.
There are other serial driver in tree, like the amba-pl*, which also
have this kind of a loop but without the printk (and were based on this
driver).

Remove the printk which might trigger in otherwise valid situtations.
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

There's an error when compiled with restrict:

drivers/tty/serial/kgdboc.c: In function ‘configure_kgdboc’:
drivers/tty/serial/kgdboc.c:137:2: error: ‘strcpy’ source argument is the same
as destination [-Werror=restrict]
  strcpy(config, opt);
  ^~~~~~~~~~~~~~~~~~~

As the error implies, this is from trying to use config as both source and
destination. Drop the call to the function where config is the argument
since nothing else happens in the function.
Signed-off-by: Laura Abbott <labbott@redhat.com>
Reviewed-by: Daniel Thompson <daniel.thompson@linaro.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

pr_* is preferred according to scripts/checkpatch.pl.

Cc: jason.wessel@windriver.com
Cc: gregkh@linuxfoundation.org
Cc: jslaby@suse.com
Signed-off-by: He Zhe <zhe.he@windriver.com>
Acked-by: Daniel Thompson <daniel.thompson@linaro.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

kgdboc_option_setup does not check input argument before passing it
to strlen. The argument would be a NULL pointer if "ekgdboc", without
its value, is set in command line and thus cause the following panic.

PANIC: early exception 0xe3 IP 10:ffffffff8fbbb620 error 0 cr2 0x0
[    0.000000] CPU: 0 PID: 0 Comm: swapper Not tainted 4.18-rc8+ #1
[    0.000000] RIP: 0010:strlen+0x0/0x20
...
[    0.000000] Call Trace
[    0.000000]  ? kgdboc_option_setup+0x9/0xa0
[    0.000000]  ? kgdboc_early_init+0x6/0x1b
[    0.000000]  ? do_early_param+0x4d/0x82
[    0.000000]  ? parse_args+0x212/0x330
[    0.000000]  ? rdinit_setup+0x26/0x26
[    0.000000]  ? parse_early_options+0x20/0x23
[    0.000000]  ? rdinit_setup+0x26/0x26
[    0.000000]  ? parse_early_param+0x2d/0x39
[    0.000000]  ? setup_arch+0x2f7/0xbf4
[    0.000000]  ? start_kernel+0x5e/0x4c2
[    0.000000]  ? load_ucode_bsp+0x113/0x12f
[    0.000000]  ? secondary_startup_64+0xa5/0xb0

This patch adds a check to prevent the panic.

Cc: stable@vger.kernel.org
Cc: jason.wessel@windriver.com
Cc: gregkh@linuxfoundation.org
Cc: jslaby@suse.com
Signed-off-by: He Zhe <zhe.he@windriver.com>
Reviewed-by: Daniel Thompson <daniel.thompson@linaro.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Enable automatic flow control which should ensure that there is no
mainteinance in connection for zcu100 BT case.
Signed-off-by: Michal Simek <michal.simek@xilinx.com>
Acked-by: Nava kishore Manne <navam@xilinx.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Record port ID in device data structure to be have it connected to
certain instance.
Signed-off-by: Michal Simek <michal.simek@xilinx.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Every instance is registering own struct console and struct uart_driver
with minor number which corresponds to alias ID (or 0 now) and with 1 uart
port. The same alias ID is saved to tty_driver->name_base which is key
field for creating ttyPSX name.

Because name_base and minor number are setup already there is no need to
setup any port->line number because 0 is the right value.

Unfortunately this driver is setting up major number to 0 for using
dynamic assignment and kernel is allocating different major numbers for
every instance instead of using the same major and different minor
number.

~# ls -la /dev/ttyPS*
crw-------    1 root     root      252,   0 Jan  1 03:36 /dev/ttyPS0
crw--w----    1 root     root      253,   1 Jan  1 00:00 /dev/ttyPS1

When major number is not 0. For example 252 then major/minor
combinations are in expected form

~# ls -la /dev/ttyPS*
crw-------    1 root     root      252,   0 Jan  1 04:04 /dev/ttyPS0
crw--w----    1 root     root      252,   1 Jan  1 00:00 /dev/ttyPS1

Driver is not freeing struct cdns_uart_console in case that instance is
not used as console. The reason is that console is incorrectly unregistred
and "console [0] disabled" message will be shown.
Signed-off-by: Michal Simek <michal.simek@xilinx.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Change logic how console_port is setup by using CON_ENABLED flag
instead of index. There will be unique cdns_uart_console() structures
that's why code can't use id for console_port assignment.
Signed-off-by: Michal Simek <michal.simek@xilinx.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

This is preparation step for dynamic port allocation without
CDNS_UART_NR_PORTS macro. Fill the structure only once at probe.
Signed-off-by: Michal Simek <michal.simek@xilinx.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Register uart driver in probe to be able to register one device with
unique major/minor separately. Also calculate number of instances of
this driver to be able to call uart_unregister_driver() when there is no
instance.
Signed-off-by: Michal Simek <michal.simek@xilinx.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

This cosmetic change is done only for having next patch much easier to
read. Moving id setup higher in probe is not affecting any usage of this
driver and it also simplify error path.
Signed-off-by: Michal Simek <michal.simek@xilinx.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

cdns_uart_suspend()/resume() and remove() are using static reference
to struct uart_driver. Assign this reference to private data structure
as preparation step for dynamic struct uart_driver allocation.
Signed-off-by: Michal Simek <michal.simek@xilinx.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

The driver's suspend/resume functions were buggy.
If UART node contains any child node in the DT and
the child is established a communication path with
the parent UART. The relevant /dev/ttyPS* node will
be not available for other operations.
If the driver is trying to do any operations like
suspend/resume without checking the tty->dev status
it leads to the kernel crash/hang.

This patch fix this issue by call the device_may_wake()
with the generic parameter of type struct device.
in the uart suspend and resume paths.

It also fixes a race condition in the uart suspend
path(i.e uart_suspend_port() should be called at the
end of cdns_uart_suspend API this path updates the same)
Signed-off-by: Nava kishore Manne <navam@xilinx.com>
Signed-off-by: Michal Simek <michal.simek@xilinx.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Writing zero and NULLs to already initialized fields is not needed.
Remove this additional writes.
Signed-off-by: Michal Simek <michal.simek@xilinx.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

When console device is rebinded, console_setup() is called again.
But marking it as __init means that function will be clear after boot is
complete. If console device is binded again console_setup() is not found
and error "Unable to handle kernel paging request at virtual address"
is reported.
Signed-off-by: Michal Simek <michal.simek@xilinx.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>