This reverts commit 9e7b399d.

Commit ("9e7b399d") causes the following warning and sometimes
also hangs the system:

------------[ cut here ]------------
 WARNING: CPU: 0 PID: 0 at kernel/locking/mutex.c:868 mutex_trylock+0x20c/0x22c()
 DEBUG_LOCKS_WARN_ON(in_interrupt())
 Modules linked in:
CPU: 0 PID: 0 Comm: swapper/0 Not tainted 4.2.0-rc7-next-20150818-00001-g14418a6 #4
Hardware name: Freescale i.MX6 Quad/DualLite (Device Tree)
Backtrace:
[<80012f08>] (dump_backtrace) from [<800130a4>] (show_stack+0x18/0x1c)
r6:00000364 r5:00000000 r4:00000000 r3:00000000
[<8001308c>] (show_stack) from [<807902b8>] (dump_stack+0x88/0xa4)
[<80790230>] (dump_stack) from [<8002a604>] (warn_slowpath_common+0x80/0xbc)
r5:807945c4 r4:80ab3b50
[<8002a584>] (warn_slowpath_common) from [<8002a6e4>] (warn_slowpath_fmt+0x38/0x40)
r8:00000000 r7:8131100c r6:8054c3cc r5:8131300c r4:80b0a570
[<8002a6b0>] (warn_slowpath_fmt) from [<807945c4>] (mutex_trylock+0x20c/0x22c)
r3:8095d0d8 r2:8095ab28
[<807943b8>] (mutex_trylock) from [<8054c3cc>] (clk_prepare_lock+0x14/0xf4)
r7:8131100c r6:be3f0c80 r5:00000037 r4:be3f0c80
[<8054c3b8>] (clk_prepare_lock) from [<8054dbfc>] (clk_prepare+0x18/0x30)
r5:00000037 r4:be3f0c80
[<8054dbe4>] (clk_prepare) from [<8036a600>] (imx_console_write+0x30/0x244)
r4:812d0bc8 r3:8132b9a4

To reproduce the problem we only need to let the board idle for something
like 30 seconds.

Tested on a imx6q-sabresd.
Signed-off-by: NFabio Estevam <fabio.estevam@freescale.com>
Reviewed-by: NEduardo Valentin <edubezval@gmail.com>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

This change teaches the imx serial driver to save its
context and restore it across suspend and resume path.
To do so, it introduces serial_imx_restore_context()
and serial_imx_save_context() functions. They use
a shadow set of registers to save key registers
and restore them accordingly. These functions can
be reused on other situations, when the device
context is lost.

Cc: Fabio Estevam <festevam@gmail.com>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Jiri Slaby <jslaby@suse.com>
Cc: linux-serial@vger.kernel.org
Cc: linux-kernel@vger.kernel.org
Signed-off-by: NEduardo Valentin <edubezval@gmail.com>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

This patch sets RTSDEN bit when going into idle (Stop mode).
We add the RTSDEN for the case RTS is sent from
the remote connection. This way we allow the system
to wakeup when RTS is received.

Cc: Fabio Stevam <festevam@gmail.com>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Jiri Slaby <jslaby@suse.com>
Cc: linux-serial@vger.kernel.org
Cc: linux-kernel@vger.kernel.org
Signed-off-by: NEduardo Valentin <edubezval@gmail.com>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

This change is a code reorganization. Here we introduce
serial_imx_enable_wakeup() helper function to do
the job of configuring and preparing wakeup sources
on imx serial device. The idea is to allow other
parts of the code to call this function whenever
the device is known to go to idle.

Cc: Fabio Estevam <festevam@gmail.com>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Jiri Slaby <jslaby@suse.com>
Cc: linux-serial@vger.kernel.org
Cc: linux-kernel@vger.kernel.org
Signed-off-by: NEduardo Valentin <edubezval@gmail.com>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

The current code attempts to prepare clk_per and clk_ipg
before using the device. However, the result is an extra
prepare call on each clock. Here is the output of uart
clocks (only uart enabled and used as console):

$  grep uart /sys/kernel/debug/clk/clk_summary
 uart_serial           1            2    80000000          0 0
       uart           1            2    66000000          0 0

This patch balances the calls of prepares. The result is:

$  grep uart /sys/kernel/debug/clk/clk_summary
 uart_serial           1            1    80000000          0 0
       uart           1            1    66000000          0 0

Cc: Fabio Estevam <festevam@gmail.com>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Jiri Slaby <jslaby@suse.com>
Cc: linux-serial@vger.kernel.org
Cc: linux-pm@vger.kernel.org
Cc: linux-kernel@vger.kernel.org
Signed-off-by: NEduardo Valentin <edubezval@gmail.com>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

When system goes into low power states like SUSPEND_MEM and
HIBERNATION, the hardware IP block may be powered off to reduce
the power consumption. This power down may cause problems on
some imx platforms, because the hardware settings are reset to
its power on default values which may differ from the ones when
it power off. This patch added the dev_pm_ops and implemented
two callbacks: suspend_noirq and resume_noirq, which will save
the necessory hardware parameters right before power down and
recover them before system uses the hardware.

Because added the dev_pm_ops, the old suspend/resume callbacks
under platform_driver will not be called any more. Changed their
prototypes and moved those two callbacks into dev_pm_ops too.
Signed-off-by: NShenwei Wang <shenwei.wang@freescale.com>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

This reverts commit e95044ba.

Commit e95044ba ("tty: serial: imx.c: Reset UART before activating
interrupts") terribly messes up with the console on mx6 boards, so
let's revert it.
Reported-by: Nkernelci.org bot <bot@kernelci.org>
Cc: David Jander <david@protonic.nl>
Signed-off-by: NFabio Estevam <fabio.estevam@freescale.com>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

This reverts commit 068500e0.

According to some tests, SDMA support is broken at least for i.MX6 without
HW flow control. Different forms of data-corruption appear either with
the ROM firmware for the SDMA controller as well as when loading Freescale
provided SDMA firmware versions 1.1 or 3.1.
Signed-off-by: NDavid Jander <david@protonic.nl>
Cc: stable <stable@vger.kernel.org>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

If the UART has been in use before this driver was loaded, IRQs might be
active and get fired as soon as we set the handler, which will crash
in the spin_lock_irqsave(&sport->port.lock, flags) because port.lock is
not initialized until the port is added at the end of probe.
Signed-off-by: NDavid Jander <david@protonic.nl>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

To prevent problems with interrupt latency, and due to the fact, that
the error will be counted anyway (icount.overrun), the dev_err is simply
removed.

Background:
If an rx-fifo overflow occurs a dev_err message was called in interrupt
context. Since dev_err messages are written to console in a synchronous way
(unbuffered), and console may be a serial terminal, this leads to a
highly increased interrupt-latency (several milliseconds).
As a result of the high latency more rx-fifo overflows will happen, and
therefore a feedback loop of errors is created.
Signed-off-by: NManfred Schlaegl <manfred.schlaegl@gmx.at>
Acked-By: NAlexander Stein <alexander.stein@systec-electronic.com>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

As can be seen in function uart_insert_char (serial_core) the element
buf_overrun of struct uart_icount is used to count overruns of
tty-buffer.
Added support for counting of overruns in imx driver analogue to
serial_core.
Signed-off-by: NManfred Schlaegl <manfred.schlaegl@gmx.at>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

Disable interrupts before requesting them in order to fix a kernel oops
after lauching a kernel via kexec.

Tested on a imx6sl-evk board.
Signed-off-by: NFabio Estevam <fabio.estevam@freescale.com>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

The driver configures the IDLE condition to interrupt the SDMA engine.
Since the SDMA UART ROM script doesn't clear the IDLE bit itself, this
caused repeated 1-byte DMA transfers, regardless of available data in the
RX FIFO. Also, when returning due to the IDLE condition, the UART ROM
script already increased its counter, causing residue to be off by one.

This patch clears the IDLE condition to avoid repeated 1-byte DMA transfers
and decreases count by when the DMA transfer was aborted due to the IDLE
condition, fixing serial transfers using DMA on i.MX6Q.
Reported-by: NPeter Seiderer <ps.report@gmx.net>
Signed-off-by: NPhilipp Zabel <p.zabel@pengutronix.de>
Tested-by: NFabio Estevam <fabio.estevam@freescale.com>
Cc: stable <stable@vger.kernel.org>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

The platform_device_id is not modified by the driver and core uses it as
const.
Signed-off-by: NKrzysztof Kozlowski <k.kozlowski.k@gmail.com>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

The return value from imx_setup_ufcr() is always 0 and its value is never
checked, so better to remove the return value.
Signed-off-by: NFabio Estevam <fabio.estevam@freescale.com>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

Previously Soft Reset (clear of SRST bit in UCR2 register)
of UART in startup is not protected by lock, which may have race
with console_write, as console_write may occur at anytime even
when UART port is shutdown.

To avoid this race, protect Soft reset of UART port with spin_lock.
Signed-off-by: NJiada Wang <jiada_wang@mentor.com>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

Commit 17b8f2a3 ("serial: imx: add support for half duplex rs485")
introduced the following build warning:

drivers/tty/serial/imx.c: In function 'imx_set_termios':
drivers/tty/serial/imx.c:1301:7: warning: suggest explicit braces to avoid ambiguous 'else' [-Wparentheses]

Add the suggested braces to avoid the build warning.
Signed-off-by: NFabio Estevam <fabio.estevam@freescale.com>
Acked-by: NUwe Kleine-König <u.kleine-koenig@pengutronix.de>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

The transmitter is expected to be controlled by the UART's RTS pin.
Signed-off-by: NUwe Kleine-König <u.kleine-koenig@pengutronix.de>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

Support for IRDA was added in 2009 in commit v2.6.31-rc1~399^2~2. There
are no in-tree users.
Signed-off-by: NUwe Kleine-König <u.kleine-koenig@pengutronix.de>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

Signed-off-by: NUwe Kleine-König <u.kleine-koenig@pengutronix.de>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

Fix indention, remove old address of the FSF, remove in-file changelog,
mention Freescale.
Signed-off-by: NUwe Kleine-König <u.kleine-koenig@pengutronix.de>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

There is no benefit in keeping this information in RAM when it's not
used any more, so better use function local variables instead.

These members are unused since c0d1c6b0 ("serial: imx: Fix the
reporting of interrupts")
Signed-off-by: NUwe Kleine-König <u.kleine-koenig@pengutronix.de>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

This if (0) exists since the driver was introduced in commit
c49bde83eb6a ([ARM PATCH] 1956/2: Re: Motorola i.MX serial driver)
back in 2004.
Signed-off-by: NUwe Kleine-König <u.kleine-koenig@pengutronix.de>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

The writeable bits in the USR2 register are all "write 1 to
clear" so only write the bits that actually should be cleared.

Fixes: f1f836e4 ("serial: imx: Add Rx Fifo overrun error message")
Signed-off-by: NUwe Kleine-König <u.kleine-koenig@pengutronix.de>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

UBRC is a read-only register, so we should not store and restore it inside
imx_flush_buffer().
Reported-by: NFugang Duan <B38611@freescale.com>
Signed-off-by: NFabio Estevam <fabio.estevam@freescale.com>
Acked-by: NFugang Duan <B38611@freescale.com>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

Make of_device_id array const.
Signed-off-by: NSanjeev Sharma <Sanjeev_Sharma@mentor.com>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

When running an userspace program that does a 'tcflush(fd, TCIOFLUSH)' call
we still see the last received character in the URXD register afterwards.

Clear UCR2_SRST bit so that the UART FIFO is flushed properly.

Since UCR2_SRST also resets some UART registers, we need to save and restore
some of them.
Signed-off-by: NFabio Estevam <fabio.estevam@freescale.com>
Tested-by: NFugang Duan <B38611@freescale.com>
Acked-by: NJason Liu <r64343@freecale.com>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

When IGNPAR is set in termios->c_iflag,  characters with
framing errors should be ignored.
Signed-off-by: NEric Nelson <eric.nelson@boundarydevices.com>
Reviewed-by: NPeter Hurley <peter@hurleysoftware.com>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

If IGNPAR/INPCK are clear in termios->c_iflag,  characters
received with parity or framing errors should be preserved
and passed to the upper layers of the tty stack.

Specifically, the decision of whether to set the character
value to zero should be made by n_tty.c/n_tty_receive_parity_error().
Signed-off-by: NEric Nelson <eric.nelson@boundarydevices.com>
Reviewed-by: NPeter Hurley <peter@hurleysoftware.com>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

This patch adds Software flow control support in DMA mode.
Signed-off-by: NJiada Wang <jiada_wang@mentor.com>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

After send out x_char in UART driver, x_char needs to be cleared
by UART driver itself, otherwise data in TXFIFO can no longer be
sent out.
Also tx counter needs to be increased to keep track of correct
number of transmitted data.
Signed-off-by: NJiada Wang <jiada_wang@mentor.com>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

Other than enable Receiver Overrun Interrupt Enable (UCR4_OREN)
in start_tx interface, UCR4_OREN should be enabled before enable
of Receiver.
Signed-off-by: NJiada Wang <jiada_wang@mentor.com>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

Start rx_dma once RXFIFO is not empty that can avoid dma request lost
and causes data delay issue.
Signed-off-by: NRobin Gong <b38343@freescale.com>
Signed-off-by: NFugang Duan <B38611@freescale.com>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

DMA mode for UART can be used even w/o HW flow control with RTS/CTS.
So it need to be initialized and enabled earlier.
Signed-off-by: NAnton Bondarenko <anton_bondarenko@mentor.com>
Signed-off-by: NJiada Wang <jiada_wang@mentor.com>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

Terminating the DMA, make sure the interrupt is disabled, too.
This fixes random kernel Oops due to dma_tx_call() called for
invalid transmissions.

If we disable the TDMAEN, make sure it's enabled again if a TX
DMA is started.
Signed-off-by: NJiada Wang <jiada_wang@mentor.com>
Signed-off-by: NDirk Behme <dirk.behme@de.bosch.com>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

Currently in dma_tx_callback(), no matter if there is still
remaining data pending in circle buffer or not, DMA transmit
will be terminated.

This will result in some data never get transmitted.
In order to fix this issue, call imx_dma_tx() again in
dma_tx_callback, when there is pending data and uart hasn't
been stopped.
Signed-off-by: NJiada Wang <jiada_wang@mentor.com>
Signed-off-by: NDirk Behme <dirk.behme@de.bosch.com>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

This reverts commit 2ad28e3e.

Instead of always wake up write_wait process in TX callback,
TX callback should call imx_dma_tx() again, and let imx_dma_tx
transfer the remaining data in circle buffer.

The issue with commit 2ad28e3e is, in case there is remaining
data in circle buffer, but no process is waiting on write_wait
queue, then as no following uart_write() will be called after
uart_write_wakeup(), thus cause data loss.

Moreover according to Documentation/serial/driver, uart_write_wakeup()
should be called in case the transmit buffer have dropped below
a threshold.
Signed-off-by: NJiada Wang <jiada_wang@mentor.com>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

To synchronize between dma_tx_callback() and imx_dma_tx() use the same
variable, dma_is_txing. This prevents any race between these two functions
and ensures that a new DMA can start only after the first has been
finished.

Before the new DMA can be set up, update the circular buffer logic, first.
Therefore, change dma_is_txing after that update, instead of before.

While doing this, in dma_tx_callback() extend the locking to dma_unmap_sg()
and the update of dma_is_txing.
Signed-off-by: NDirk Behme <dirk.behme@de.bosch.com>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

First, reformat the code to exit immediately. This allows us to add
more code in more readable format.

In case the TX DMA was still running, remove and disable it's resources.
Signed-off-by: NDirk Behme <dirk.behme@de.bosch.com>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

In case dmaengine_prep_slave_sg() fails, add the missing dma_unmap_sg().
Signed-off-by: NDirk Behme <dirk.behme@de.bosch.com>
Signed-off-by: NAnton Bondarenko <anton_bondarenko@mentor.com>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>