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>

For many years omap variants have been setting the runtime PM
autosuspend delay to -1 to prevent unsafe policy with lossy first
character on wake-up. The user must specifically enable the timeout
for UARTs if desired.

We must not enable the workaround for serdev devices though. It leads
into UARTs not idling if no serdev devices are loaded and there is no
sysfs entry to configure the UART in that case. And this means that
my PM may not work unless the serdev modules are loaded.

We can detect a serdev device being configured based on a dts child
node, and we can simply skip the workround in that case. And the
serdev driver can idle the port during runtime when suitable if an
out-of-band wake-up GPIO line exists for example.

Let's also add some comments to the workaround while at it.

Cc: Johan Hovold <johan@kernel.org>
Signed-off-by: NTony Lindgren <tony@atomide.com>
Link: https://lore.kernel.org/r/20190723115400.46432-1-tony@atomide.comSigned-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

This patch permits the usage for GPIOs to control
the CTS/RTS/DTR/DSR/DCD/RI signals.

Changed by Stefan:
Only call mctrl_gpio_init(), if the device has no ACPI companion device
to not break existing ACPI based systems. Also only use the mctrl_gpio_
functions when "gpios" is available.

Use MSR / MCR <-> TIOCM wrapper functions.
Signed-off-by: NYegor Yefremov <yegorslists@googlemail.com>
Signed-off-by: NStefan Roese <sr@denx.de>
Reviewed-by: NAndy Shevchenko <andriy.shevchenko@linux.intel.com>
Reviewed-by: NMika Westerberg <mika.westerberg@linux.intel.com>
Tested-by: NYegor Yefremov <yegorslists@googlemail.com>
Cc: Mika Westerberg <mika.westerberg@linux.intel.com>
Cc: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Cc: Giulio Benetti <giulio.benetti@micronovasrl.com>
Cc: Yegor Yefremov <yegorslists@googlemail.com>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

Factor out similar code pieces that set or clear UART_IER_THRI bit to
serial8250_{set,clear}_THRI() helpers.
Signed-off-by: NAndy Shevchenko <andriy.shevchenko@linux.intel.com>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

8250_omap driver uses clock-frequency DT property to obtain functional
clk frequency. This is not ideal as users need to calculate functional
clk frequency offline and populate it in DT.
Therefore add support to obtain functional clock frequency using clk
APIs when clock-frequency DT property is not defined.
Suggested-by: NLokesh Vutla <lokeshvutla@ti.com>
Signed-off-by: NVignesh R <vigneshr@ti.com>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

8250_omap is DT only driver so dev->of_node always exists. Drop check
for existence of valid dev->of_node to simplify omap8250_probe().
Signed-off-by: NVignesh R <vigneshr@ti.com>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

Let's take advantage of the new ("serial: core: Allow processing sysrq
at port unlock time") to handle sysrqs more cleanly.
Signed-off-by: NDouglas Anderson <dianders@chromium.org>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

AM654 uses a UART controller that is compatible (partially) with
existing 8250 UART, however, has a few differences with respect to DMA
support and control paths. Introduce a base definition that allows us
to build up the differences in follow on patches.

Cc: Sekhar Nori <nsekhar@ti.com>
Cc: Vignesh R <vigneshr@ti.com>
Signed-off-by: NNishanth Menon <nm@ti.com>
Acked-by: NTony Lindgren <tony@atomide.com>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

I noticed that unused UARTs won't necessarily idle properly always
unless at least one byte tx transfer is done first.

After some debugging I narrowed down the problem to the scr register
dma configuration bits that need to be set before softreset for the
clocks to idle. Unless we do this, the module clkctrl idlest bits
may be set to 1 instead of 3 meaning the clock will never idle and
is blocking deeper idle states for the whole domain.

This might be related to the configuration done by the bootloader
or kexec booting where certain configurations cause the 8250 or
the clkctrl clock to jam in a way where setting of the scr bits
and reset is needed to clear it. I've tried diffing the 8250
registers for the various modes, but did not see anything specific.
So far I've only seen this on omap4 but I'm suspecting this might
also happen on the other clkctrl using SoCs considering they
already have a quirk enabled for UART_ERRATA_CLOCK_DISABLE.

Let's fix the issue by configuring scr before reset for basic dma
even if we don't use it. The scr register will be reset when we do
softreset few lines after, and we restore scr on resume. We should
do this for all the SoCs with UART_ERRATA_CLOCK_DISABLE quirk flag
set since the ones with UART_ERRATA_CLOCK_DISABLE are all based
using clkctrl similar to omap4.

Looks like both OMAP_UART_SCR_DMAMODE_1 | OMAP_UART_SCR_DMAMODE_CTL
bits are needed for the clkctrl to idle after a softreset.

And we need to add omap4 to also use the UART_ERRATA_CLOCK_DISABLE
for the related workaround to be enabled. This same compatible
value will also be used for omap5.

Fixes: cdb929e4 ("serial: 8250_omap: workaround errata around idling UART after using DMA")
Cc: Keerthy <j-keerthy@ti.com>
Cc: Matthijs van Duin <matthijsvanduin@gmail.com>
Cc: Sekhar Nori <nsekhar@ti.com>
Cc: Tero Kristo <t-kristo@ti.com>
Signed-off-by: NTony Lindgren <tony@atomide.com>
Cc: stable <stable@vger.kernel.org>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

Enable/Clear module level UART wakeup in UART_OMAP_WER register based on
return value of device_may_wakeup() in .suspend(). This allows
userspace to use sysfs to control the ability of UART to wakeup the
system from deep sleep state. Register is restored back in .startup()
call that happens as part of resume sequence.

With this patch, userspace can control UART wakeup capability via sysfs:
To enable wakeup capability:
echo enabled >  /sys/class/tty/ttyXX/device/power/wakeup
For disabling wakeup capability:
echo disabled > /sys/class/tty/ttyXX/device/power/wakeup

Note that the UART wakeup events configured in the 8250 hardware only
work for idle modes that do not cut off power for the UART. For deeper
idle states, dedicated padconf wakeirqs must be used. Or in some cases
the UART RX pin can be remuxed to GPIO input if the GPIO block stays
powered.
Signed-off-by: NVignesh R <vigneshr@ti.com>
Tested-by: NTony Lindgren <tony@atomide.com>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

omap_8250_throttle() is called when tty RX buffer is about to overflow
and can no longer keep up with the rate at which UART is receiving data.
So, the expectation of this callback, is that UART stops RX and asserts
HW flow control to signal the sender to stop sending more data.
omap_8250_throttle() disables RX FIFO interrupts thus FIFO is no longer
serviced, leading to assertion of flow control once RX FIFO is full.
But, this does not work when DMA is enabled as driver keeps queuing new
RX DMA request in completion handler without brothering about throttling
request made by the higher layer.
This patch introduces a flag that can be used to determine whether or
not to queue next RX DMA request based on throttling request.

Without this patch, tty buffer overflows are reported at higher
baudrates.
Signed-off-by: NVignesh R <vigneshr@ti.com>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

Fixed a spelling error in a comment.
Signed-off-by: NRolf Evers-Fischer <rolf.evers.fischer@aptiv.com>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

It's good to have SPDX identifiers in all files to make it easier to
audit the kernel tree for correct licenses.

Update the drivers/tty files files with the correct SPDX license
identifier based on the license text in the file itself.  The SPDX
identifier is a legally binding shorthand, which can be used instead of
the full boiler plate text.

This work is based on a script and data from Thomas Gleixner, Philippe
Ombredanne, and Kate Stewart.

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: Chris Metcalf <cmetcalf@mellanox.com>
Cc: Jiri Kosina <jikos@kernel.org>
Cc: David Sterba <dsterba@suse.com>
Cc: James Hogan <jhogan@kernel.org>
Cc: Rob Herring <robh@kernel.org>
Cc: Eric Anholt <eric@anholt.net>
Cc: Stefan Wahren <stefan.wahren@i2se.com>
Cc: Florian Fainelli <f.fainelli@gmail.com>
Cc: Ray Jui <rjui@broadcom.com>
Cc: Scott Branden <sbranden@broadcom.com>
Cc: bcm-kernel-feedback-list@broadcom.com
Cc: "James E.J. Bottomley" <jejb@parisc-linux.org>
Cc: Helge Deller <deller@gmx.de>
Cc: Joachim Eastwood <manabian@gmail.com>
Cc: Matthias Brugger <matthias.bgg@gmail.com>
Cc: Masahiro Yamada <yamada.masahiro@socionext.com>
Cc: Tobias Klauser <tklauser@distanz.ch>
Cc: Russell King <linux@armlinux.org.uk>
Cc: Vineet Gupta <vgupta@synopsys.com>
Cc: Richard Genoud <richard.genoud@gmail.com>
Cc: Alexander Shiyan <shc_work@mail.ru>
Cc: Baruch Siach <baruch@tkos.co.il>
Cc: "Maciej W. Rozycki" <macro@linux-mips.org>
Cc: "Uwe Kleine-König" <kernel@pengutronix.de>
Cc: Pat Gefre <pfg@sgi.com>
Cc: "Guilherme G. Piccoli" <gpiccoli@linux.vnet.ibm.com>
Cc: Jason Wessel <jason.wessel@windriver.com>
Cc: Vladimir Zapolskiy <vz@mleia.com>
Cc: Sylvain Lemieux <slemieux.tyco@gmail.com>
Cc: Carlo Caione <carlo@caione.org>
Cc: Kevin Hilman <khilman@baylibre.com>
Cc: Liviu Dudau <liviu.dudau@arm.com>
Cc: Sudeep Holla <sudeep.holla@arm.com>
Cc: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>
Cc: Andy Gross <andy.gross@linaro.org>
Cc: David Brown <david.brown@linaro.org>
Cc: "Andreas Färber" <afaerber@suse.de>
Cc: Kevin Cernekee <cernekee@gmail.com>
Cc: Laxman Dewangan <ldewangan@nvidia.com>
Cc: Thierry Reding <thierry.reding@gmail.com>
Cc: Jonathan Hunter <jonathanh@nvidia.com>
Cc: Barry Song <baohua@kernel.org>
Cc: Patrice Chotard <patrice.chotard@st.com>
Cc: Maxime Coquelin <mcoquelin.stm32@gmail.com>
Cc: Alexandre Torgue <alexandre.torgue@st.com>
Cc: "David S. Miller" <davem@davemloft.net>
Cc: Peter Korsgaard <jacmet@sunsite.dk>
Cc: Timur Tabi <timur@tabi.org>
Cc: Tony Prisk <linux@prisktech.co.nz>
Cc: Michal Simek <michal.simek@xilinx.com>
Cc: "Sören Brinkmann" <soren.brinkmann@xilinx.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Kate Stewart <kstewart@linuxfoundation.org>
Cc: Philippe Ombredanne <pombredanne@nexb.com>
Cc: Jiri Slaby <jslaby@suse.com>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

Add a define for the maximum baud rate divisor, to improve code
readability.
Signed-off-by: NEd Blake <ed.blake@sondrel.com>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

DMA RX completion handler for UART is called from a tasklet and hence
may be delayed depending on the system load. In meanwhile, there may be
RX timeout interrupt which can get serviced first before DMA RX
completion handler is executed for the completed transfer.
omap_8250_rx_dma_flush() which is called on RX timeout interrupt makes
sure that the DMA RX buffer is pushed and then the FIFO is drained and
also queues a new DMA request. But, when DMA RX completion handler
executes, it will erroneously flush the currently queued DMA transfer
which sometimes results in data corruption and double queueing of DMA RX
requests.

Fix this by checking whether RX completion is for the currently queued
transfer or not. And also hold port lock when in DMA completion to avoid
race wrt RX timeout handler preempting it.
Signed-off-by: NVignesh R <vigneshr@ti.com>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

Kernel always writes log messages to console via
serial8250_console_write()->serial8250_console_putchar() which directly
accesses UART_TX register _without_ using DMA.

But, if other processes like systemd using same UART port, then these
writes are handled by a different code flow using 8250_omap driver where
there is provision to use DMA.

It seems that it is possible that both DMA and CPU might simultaneously
put data to UART FIFO and lead to potential loss of data due to FIFO
overflow and weird data corruption. This happens when both kernel
console and userspace tries to write simultaneously to the same UART
port. Therefore, disable DMA on kernel console port to avoid potential
race between CPU and DMA.
Signed-off-by: NVignesh R <vigneshr@ti.com>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

Otherwise the interconnect related code implementing PM runtime will
produce these errors on a failed probe:

omap_uart 48066000.serial: omap_device: omap_device_enable() called from invalid state 1
omap_uart 48066000.serial: use pm_runtime_put_sync_suspend() in driver?

Note that we now also need to check for priv in omap8250_runtime_suspend()
as it has not yet been registered if probe fails. And we need to use
pm_runtime_put_sync() to properly idle the device like we already do
in omap8250_remove().

Fixes: 61929cf0 ("tty: serial: Add 8250-core based omap driver")
Signed-off-by: NTony Lindgren <tony@atomide.com>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

8250 UART DMA support was marked broken by default as it was not
possible to pause ongoing RX DMA transfer. Now that both SDMA and
EDMA can support pause operation for RX DMA transactions, don't set
rx_dma_broken to true by default. With this patch 8250_omap driver will
use DMA by default.
Signed-off-by: NVignesh R <vigneshr@ti.com>
Acked-by: NTony Lindgren <tony@atomide.com>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

UART uses as EDMA as dma engine on AM437x SoC and therefore, requires
OMAP_DMA_TX_KICK quirk just like AM33xx. So, enable OMAP_DMA_TX_KICK
quirk for AM437x platform as well. While at that, drop use of
of_machine_is_compatible() and instead pass quirks via device data.
Signed-off-by: NVignesh R <vigneshr@ti.com>
Acked-by: NTony Lindgren <tony@atomide.com>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

It is possible that DMA transfer is already complete but, completion
handler is yet to be called, when dmaengine_pause() is called in case of
error condition(like break/rx timeout). This leads to dmaengine_pause()
API to return EINVAL (as descriptor is already NULL) causing
rx_dma_broken flag to be set and effectively disabling RX DMA.
Fix this by calling dmaengine_pause() only when transfer is in progress.
Signed-off-by: NVignesh R <vigneshr@ti.com>
Acked-by: NTony Lindgren <tony@atomide.com>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

Serial console is broken in v4.8-rcX. Mika and I independently bisected down to
commit 4ef03d32 ("tty/serial/8250: use mctrl_gpio helpers").

Since neither author nor anyone else didn't propose a solution we better revert
it for now.

This reverts commit 4ef03d32.

Link: https://lkml.kernel.org/r/20160809130229.GN1729@lahna.fi.intel.comSigned-off-by: NAndy Shevchenko <andriy.shevchenko@linux.intel.com>
Tested-by: NHeikki Krogerus <heikki.krogerus@linux.intel.com>
Tested-by: NMika Westerberg <mika.westerberg@linux.intel.com>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

This patch permits the usage for GPIOs to control
the CTS/RTS/DTR/DSR/DCD/RI signals.
Signed-off-by: NYegor Yefremov <yegorslists@googlemail.com>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

Introduce serial8250_out_MCR() and serial8250_in_MCR() routines, that
replace following calls:

serial_out(port, UART_MCR, val)
serial_port_out(up, UART_MCR, val)
serial_in(port, UART_MCR)

This patch is needed in order to integrate reading/writing of MCR
signals via SERIAL_MCTRL_GPIO infrastructure later.
Reviewed-by: NPeter Hurley <peter@hurleysoftware.com>
Signed-off-by: NYegor Yefremov <yegorslists@googlemail.com>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

DMA completed normally does not require termination; only terminate
paused rx dma stemming from rx dma flush.
Signed-off-by: NPeter Hurley <peter@hurleysoftware.com>
Reviewed-by: NHeikki Krogerus <heikki.krogerus@linux.intel.com>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

Using fake IIR values to perform rx dma operations unnecessarily
conflates separate operations, stopping in-progress dma with starting
new dma.

Introduce serial8250_rx_dma_flush() to handle stopping in-progress dma
[omap8250 already has equivalent omap_8250_rx_dma_flush()].
Replace rx_dma(UART_IIR_RX_TIMEOUT) with the equivalent *_rx_dma_flush(),
and rx_dma(0) with the equivalent *_rx_dma(). Handle IIR steering
in the irq handler with handle_rx_dma() helper.
Signed-off-by: NPeter Hurley <peter@hurleysoftware.com>
Reviewed-by: NHeikki Krogerus <heikki.krogerus@linux.intel.com>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

Extract the operation (restarting new rx dma) performed when error
argument is true.
Signed-off-by: NPeter Hurley <peter@hurleysoftware.com>
Reviewed-by: NHeikki Krogerus <heikki.krogerus@linux.intel.com>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

commit 27c310c5 ("serial: 8250_dma: no need to sync RX buffer")
notes the RX DMA buffer is allocated from DMA coherent memory, and
thus does not need sync'd for each transaction. The same is true
for OMAP RX DMA.
Signed-off-by: NPeter Hurley <peter@hurleysoftware.com>
Reviewed-by: NHeikki Krogerus <heikki.krogerus@linux.intel.com>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

Eliminate 'loss_cntx' local variable.
Signed-off-by: NPeter Hurley <peter@hurleysoftware.com>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

dma_err is not used other than for boolean evaluation;
substitute the actual operation directly.
Signed-off-by: NPeter Hurley <peter@hurleysoftware.com>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

up_to_u8250p() casts struct uart_port * to struct uart_8250_port *. Update code
to use it instead of open coded variant.
Signed-off-by: NAndy Shevchenko <andriy.shevchenko@linux.intel.com>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

Use software emulated RS485 direction control to provide RS485 API
existed in omap_serial driver. Note that 8250_omap issues interrupt
on shift register empty which is single prerequesite for using software
emulated RS485.
Signed-off-by: NMatwey V. Kornilov <matwey@sai.msu.ru>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

Clearing UART_MCR_RTS or UART_MCR_XONANY is unnecessary; these bits
are never set in the shadow mcr. The RTS clear is especially confusing.
Signed-off-by: NPeter Hurley <peter@hurleysoftware.com>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

The function tty_insert_flip_string() returns an int and as such it
might fail. So the result is that I kindly asked to insert 48 bytes and
the function only insterted 32.
I have no idea what to do with the remaining 16 so I think dropping them
is the only option. I also increase the buf_overrun counter so userpace
has a clue that we lost bytes.
Signed-off-by: NSebastian Andrzej Siewior <bigeasy@linutronix.de>
Tested-by: NSekhar Nori <nsekhar@ti.com>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

The 8250-omap driver requires the DMA-engine driver to support the pause
command in order to properly turn off programmed RX transfer before the
driver stars manually reading from the FIFO.
The lacking support of the requirement has been discovered recently. In
order to stay safe here we disable RX-DMA completly on probe.
The rx_dma_broken assignment on probe could be removed once we working
pause function in omap-dma.

Cc: <stable@vger.kernel.org>
Signed-off-by: NSebastian Andrzej Siewior <bigeasy@linutronix.de>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

OMAP h/w-assisted IXON flow control is borked. The transmitter becomes
stuck if XON is never received; clearing the fifos or resetting the
rx flow control bits has no effect.

Remove auto-IXANY as well, since without auto-IXON, it has no purpose.
Signed-off-by: NPeter Hurley <peter@hurleysoftware.com>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

Due to Advisory 21 as documented in AM437x errata document,
UART module cannot be disabled once DMA is used. The only
workaround is to softreset the module before disabling it.

DRA7x UARTs are compatible to AM437x UARTs in terms of
this errata and prescribed workaround.

Enable usage of workaround for this errata on DRA7x SoCs.
Signed-off-by: NSekhar Nori <nsekhar@ti.com>
Acked-by: NTony Lindgren <tony@atomide.com>
Reviewed-by: NPeter Hurley <peter@hurleysoftware.com>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

AM335x, AM437x and DRA7x SoCs have an errata[1] due to which UART
cannot be idled after it has been used with DMA.

OMAP3 has a similar sounding errata which has been worked around
in a2fc3661 ("ARM: OMAP3: Use manual idle for UARTs
because of DMA errata"). But the workaround used there does not
apply to AM335x, AM437x SoCs.

After using DMA, the UART module on these SoCs must be soft reset
to go to idle.

This patch implements that errata workaround. It is expected that
UART will be used with DMA so no explicit check for DMA usage
has been added for errata applicability.

MDR1 register needs to be restored right after soft-reset because
"UART mode" must be set in that register for module wake-up on AM335x
to work. As a result, SCR register is now used to determine if
context was lost during sleep.

[1] See Advisory 21 in AM437x errata SPRZ408B, updated April 2015.
    http://www.ti.com/lit/er/sprz408b/sprz408b.pdfSigned-off-by: NSekhar Nori <nsekhar@ti.com>
Acked-by: NTony Lindgren <tony@atomide.com>
Reviewed-by: NPeter Hurley <peter@hurleysoftware.com>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

Use of of_machine_is_compatible() for handling AM335x specific
"DMA kick" quirk in 8250_omap driver makes it ugly to extend the
quirk for other platforms. Instead use a new compatible.

The new compatible will also make it easier to take care of
other quirks on AM335x and like SoCs.

In order to not break backward DTB compatibility for users of
8250_omap driver on AM335x based boards, existing use of
of_machine_is_compatible() has not been removed.
Signed-off-by: NSekhar Nori <nsekhar@ti.com>
Acked-by: NTony Lindgren <tony@atomide.com>
Reviewed-by: NPeter Hurley <peter@hurleysoftware.com>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

The silicon errata[1] workaround implemented in a follow-on
patch, "serial: 8250_omap: workaround errata on disabling
UART after using DMA", requires MDR1 register programming.

Extract MDR1 register update into helper function,
omap8250_update_mdr1() to help with that.

[1] Advisory 21 in http://www.ti.com/lit/er/sprz408b/sprz408b.pdfSigned-off-by: NSekhar Nori <nsekhar@ti.com>
Acked-by: NTony Lindgren <tony@atomide.com>
Reviewed-by: NPeter Hurley <peter@hurleysoftware.com>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

omap_device infrastructure has a suspend_noirq hook which
runtime suspends all devices late in the suspend cycle (see
_od_suspend_noirq() in arch/arm/mach-omap2/omap_device.c)

This leads to a NULL pointer exception in 8250_omap driver
since by the time omap8250_runtime_suspend() is called, 8250_dma
driver has already set rxchan to NULL via serial8250_release_dma().

Make an explicit check to see if rxchan is NULL in
runtime_{suspend|resume} hooks to fix this.
Signed-off-by: NSekhar Nori <nsekhar@ti.com>
Acked-by: NTony Lindgren <tony@atomide.com>
Reviewed-by: NPeter Hurley <peter@hurleysoftware.com>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>