Without this patch the driver waits ~1 ms for the UART to become idle. At
115200n8 this time is (theoretically) enough to transfer 11.5 characters
(= 115200 bits/s / (10 Bits/char) * 1ms). As the mxs-auart has a fifo size
of 16 characters the clock is gated too early. The problem is worse for
lower baud rates.

This only happens to really shut down the transmitter in the middle of a
transfer if /dev/ttyAPPx isn't opened in userspace (e.g. by a getty) but
was at least once (because the bootloader doesn't disable the transmitter).

So increase the timeout to 20 ms which should be enough for 9600n8, too.
Moreover skip gating the clock if the timeout is elapsed.

Cc: stable@vger.kernel.org # v2.6.39+
Signed-off-by: NUwe Kleine-König <u.kleine-koenig@pengutronix.de>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

The handler needs to ack the pending events before actually handling them.
Otherwise a new event might come in after it it considered non-pending or
handled and is acked then without being handled. So this event is only
noticed when the next interrupt happens.

Without this patch an i.MX28 based machine running an rt-patched kernel
regularly hangs during boot.

Cc: stable@vger.kernel.org # v2.6.39+
Signed-off-by: NUwe Kleine-König <u.kleine-koenig@pengutronix.de>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

Driver core already takes care of refcounting, no need to do this on
driver level again.
Signed-off-by: NWolfram Sang <wsa@the-dreams.de>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

SMATCH correctly found an off-by-one error:

drivers/tty/serial/mxs-auart.c:889 auart_console_write() error: buffer overflow 'auart_port' 5 <= 5
Signed-off-by: NWolfram Sang <wsa@the-dreams.de>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

With the generic DMA device tree helper supported by mxs-dma driver,
client devices only need to call dma_request_slave_channel() for
requesting a DMA channel from dmaengine.
Signed-off-by: NShawn Guo <shawn.guo@linaro.org>
Acked-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>
Reviewed-by: NArnd Bergmann <arnd@arndb.de>

Now, we start converting tty buffer functions to actually use
tty_port. This will allow us to get rid of the need of tty in many
call sites. Only tty_port will needed and hence no more
tty_port_tty_get in those paths.

Now, the one where most of tty_port_tty_get gets removed:
tty_flip_buffer_push.

IOW we also closed all the races in drivers not using tty_port_tty_get
at all yet.

Also we move tty_flip_buffer_push declaration from include/linux/tty.h
to include/linux/tty_flip.h to all others while we are changing it
anyway.
Signed-off-by: NJiri Slaby <jslaby@suse.cz>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

Now, we start converting tty buffer functions to actually use
tty_port. This will allow us to get rid of the need of tty in many
call sites. Only tty_port will needed and hence no more
tty_port_tty_get in those paths.

tty_insert_flip_string this time.
Signed-off-by: NJiri Slaby <jslaby@suse.cz>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

Detected by cppcheck:
[others/linux/drivers/tty/serial/mxs-auart.c:553]: (style) Same expression on both sides of '||'.
Signed-off-by: NThomas Jarosch <thomas.jarosch@intra2net.com>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

Fix the following warning when building with W=1 option:

drivers/tty/serial/mxs-auart.c: In function 'mxs_auart_tx_chars':
drivers/tty/serial/mxs-auart.c:272:10: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
Signed-off-by: NFabio Estevam <fabio.estevam@freescale.com>
Acked-by: NMarek Vasut <marex@denx.de>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

With the patch "serial: mxs-auart: fix the wrong RTS hardware flow control" the
mainline mxs-uart driver now sets RTSEN only when hardware flow control is
enabled via software. It is not possible any longer to set RTS manually via
software. However, the manual modification is a valid operation.
Regain the possibility to set RTS via software and only set RTSEN when hardware
flow control is explicitly enabled via settermios cflag CRTSCTS.
Signed-off-by: NSteffen Trumtrar <s.trumtrar@pengutronix.de>
Cc: stable <stable@vger.kernel.org>
Reviewed-by: NHuang Shijie <b32955@freescale.com>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

We should first unmap the DMA scatter list for receiving data, and
then copy the data from the DMA buffer.

The old code misses unmap the scatter list for RX. This patch fixes it.
Signed-off-by: NHuang Shijie <b32955@freescale.com>
Tested-by: NLauri Hintsala <lauri.hintsala@bluegiga.com>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

When the DMA is enabled, the Receive Timeout interrupt is very easy to be arised
in the 3M baud rate.  The interrupt handler (aka mxs_auart_irq_handle) will call
mxs_auart_rx_chars() to handle the received data. This is not right, we can not
get the correct data from the RXFIFO now, the data have been moved to the
DMA buffer by the DMA engine.

This patch
  (1) disables the Receive Timeout Interrupt when the DMA is enabled,
  (2) and invoke the mxs_auart_rx_chars() only when the DMA is not enabled.
Signed-off-by: NHuang Shijie <b32955@freescale.com>
Tested-by: NLauri Hintsala <lauri.hintsala@bluegiga.com>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

CONFIG_HOTPLUG is going away as an option so __devexit is no
longer needed.
Signed-off-by: NBill Pemberton <wfp5p@virginia.edu>
Cc: Jiri Slaby <jirislaby@gmail.com>
Cc: Alan Cox <alan@linux.intel.com>
Acked-by: NTobias Klauser <tklauser@distanz.ch>
Cc: Lucas Tavares <lucaskt@linux.vnet.ibm.com>
Cc: Daniel Walker <dwalker@fifo99.com>
Cc: Bryan Huntsman <bryanh@codeaurora.org>
Cc: "David S. Miller" <davem@davemloft.net>
Cc: Peter Korsgaard <jacmet@sunsite.dk>
Cc: Tony Prisk <linux@prisktech.co.nz>
Acked-by: NDavid Brown <davidb@codeaurora.org>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

CONFIG_HOTPLUG is going away as an option so __devinit is no longer
needed.
Signed-off-by: NBill Pemberton <wfp5p@virginia.edu>
Cc: Jiri Slaby <jirislaby@gmail.com>
Cc: Alan Cox <alan@linux.intel.com>
Cc: Lucas Tavares <lucaskt@linux.vnet.ibm.com>
Cc: "David S. Miller" <davem@davemloft.net>
Cc: Peter Korsgaard <jacmet@sunsite.dk>
Cc: Tony Prisk <linux@prisktech.co.nz>
Acked-by: NTobias Klauser <tklauser@distanz.ch>
Acked-by: NNicolas Ferre <nicolas.ferre@atmel.com>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

CONFIG_HOTPLUG is going away as an option so __devexit_p is no longer
needed.
Signed-off-by: NBill Pemberton <wfp5p@virginia.edu>
Cc: Alan Cox <alan@linux.intel.com>
Cc: Lucas Tavares <lucaskt@linux.vnet.ibm.com>
Cc: "David S. Miller" <davem@davemloft.net>
Cc: Peter Korsgaard <jacmet@sunsite.dk>
Cc: Tony Prisk <linux@prisktech.co.nz>
Acked-by: NTobias Klauser <tklauser@distanz.ch>
Acked-by: NNicolas Ferre <nicolas.ferre@atmel.com>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

Only we meet the following conditions, we can enable the DMA support for
auart:

  (1) We enable the DMA support in the dts file, such as
      arch/arm/boot/dts/imx28.dtsi.

  (2) We enable the hardware flow control.

  (3) We use the mx28, not the mx23. Due to hardware bug(see errata: 2836),
      we can not add the DMA support to mx23.
Signed-off-by: NHuang Shijie <b32955@freescale.com>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

The current mxs-auart driver is used for both mx23 and mx28.

But in mx23, the DMA has a bug(see errata:2836). We can not add the
DMA support in mx23, but we can add DMA support to auart in mx28.

So in order to add the DMA support for the auart in mx28, we should
distinguish the distinguish SOCs.

This patch adds a new platform_device_id table and a inline function
is_imx28_auart() to distinguish the mx23 and mx28.
Signed-off-by: NHuang Shijie <b32955@freescale.com>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

The mxs_auart_probe() gets the device by the get_device().
So we should put the device in the error path to balance the
device's reference counter.
Signed-off-by: NHuang Shijie <b32955@freescale.com>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

We call the get_device() in the mxs_auart_probe().
For the balance of the reference count, we should put the
device in the mxs_auart_remove().
Signed-off-by: NHuang Shijie <shijie8@gmail.com>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

After set the AUART_CTRL0_CLKGATE, the UART will gate all the clocks off.
So the following line will not take effect.
       ................................................................
 	writel(AUART_INTR_RXIEN | AUART_INTR_RTIEN | AUART_INTR_CTSMIEN,
 			u->membase + AUART_INTR_CLR);
       ................................................................

To fix this issue, the patch moves this gate-off line to
the end of setting registers.
Signed-off-by: NHuang Shijie <shijie8@gmail.com>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

In most of the time, the driver needs to check if the cts flow control
is enabled. But now, the driver checks the ASYNC_CTS_FLOW flag manually,
which is not a grace way. So add a new wraper function to make the code
tidy and clean.
Signed-off-by: NHuang Shijie <shijie8@gmail.com>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

Without checking if the auart supports the hardware flow control or not,
the old mxs_auart_set_mctrl() asserted the RTS pin blindly.

This will causes the auart receives wrong data in the following case:
   The far-end has already started the write operation, and wait for
the auart asserts the RTS pin. Then the auart starts the read operation,
but mxs_auart_set_mctrl() may be called before we set the RTSCTS in the
mxs_auart_settermios(). So the RTS pin is asserted in a wrong situation,
and we get the wrong data in the end.

This bug has been catched when I connect the mx23(DTE) to the mx53(DCE).

This patch also replaces the AUART_CTRL2_RTS with AUART_CTRL2_RTSEN.
We should use the real the hardware flow control, not the software-controled
hardware flow control.
Signed-off-by: NHuang Shijie <b32955@freescale.com>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

Allow device tree probing.

Cc: Grant Likely <grant.likely@secretlab.ca>
Cc: Rob Herring <rob.herring@calxeda.com>
Cc: Alan Cox <alan@linux.intel.com>
Cc: <linux-serial@vger.kernel.org>
Signed-off-by: NFabio Estevam <fabio.estevam@freescale.com>
Signed-off-by: NSubodh Nijsure <snijsure@grid-net.com>
Acked-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: NShawn Guo <shawn.guo@linaro.org>

Cc: linux-serial@vger.kernel.org
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: NShawn Guo <shawn.guo@linaro.org>

This patch fixes a problem reported here:
http://article.gmane.org/gmane.linux.ports.arm.kernel/155242/match=auartSigned-off-by: NLothar Waßmann <LW@KARO-electronics.de>
Cc: stable <stable@vger.kernel.org>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

The patch converts mxs-auart driver to clk_prepare/clk_unprepare by
using helper functions clk_prepare_enable/clk_disable_unprepare.
Signed-off-by: NShawn Guo <shawn.guo@linaro.org>
Cc: Sascha Hauer <s.hauer@pengutronix.de>
Cc: Alan Cox <alan@linux.intel.com>

There is no need to call uart_write_wakeup after each character send.
Once at the end of the write sequence is enough.
Signed-off-by: NUwe Kleine-König <u.kleine-koenig@pengutronix.de>
Acked-by: NAlan Cox <alan@linux.intel.com>
Signed-off-by: NGreg Kroah-Hartman <gregkh@suse.de>

Do not include linux/device.h twice in drivers/tty/serial/mxs-auart.c .
Once is enough.
Signed-off-by: NJesper Juhl <jj@chaosbits.net>
Signed-off-by: NSascha Hauer <s.hauer@pengutronix.de>