This is to fix an issue where output will suddenly become very slow.
The problem occurs on 8250 UARTS with the hardware bug UART_BUG_THRE.

BACKGROUND
For normal UARTs (without UART_BUG_THRE): When the serial core layer
gets new transmit data and the transmitter is idle, it buffers the
data and calls the 8250s' serial8250_start_tx() routine which will
simply enable the TX interrupt in the IER register and return. This
should immediately fire a THRE interrupt and begin transmitting the
data.
For buggy UARTs (with UART_BUG_THRE): merely enabling the TX interrupt
in IER does not necessarily generate a new THRE interrupt.
Therefore, a background timer periodically checks to see if there is
pending data, and starts transmission if that is the case.

The bug happens on SMP systems when the system has nothing to transmit,
the transmit interrupt is disabled and the following sequence occurs:
- CPU0: The background timer routine serial8250_backup_timeout()
  starts and saves the state of the interrupt enable register (IER)
  and then disables all interrupts in IER. NOTE: The transmit interrupt
  (TI) bit is saved as disabled.
- CPU1: The serial core gets data to transmit, grabs the port lock and
  calls serial8250_start_tx() which enables the TI in IER.
- CPU0: serial8250_backup_timeout() waits for the port lock.
- CPU1: finishes (with TI enabled) and releases the port lock.
- CPU0: serial8250_backup_timeout() calls the interrupt routine which
  will transmit the next fifo's worth of data and then restores the
  IER from the previously saved value (TI disabled).
At this point, as long as the serial core has more transmit data
buffered, it will not call serial8250_start_tx() again and the
background timer routine will slowly transmit the data.

The fix is to have serial8250_start_tx() get the port lock before
it saves the IER state and release it after restoring IER. This will
prevent serial8250_start_tx() from running in parallel.
Signed-off-by: NAl Cooper <alcooperx@gmail.com>
Cc: stable <stable@kernel.org>
Signed-off-by: NGreg Kroah-Hartman <gregkh@suse.de>

Data definiton "VendorID=10DB, device_id=800D" is already defined.
This patch deletes the duplicate definition.
Signed-off-by: NTomoya MORINAGA <tomoya-linux@dsn.okisemi.com>
Signed-off-by: NGreg Kroah-Hartman <gregkh@suse.de>

This patch adds support for the Rosewill RC-305 four-port PCI serial
card, and probably any other four-port serial cards based on the
Moschip MCS9865 chip, assuming that the EEPROM on the card was
programmed in accordance with Table 6 of the MCS9865 EEPROM
Application Note version 0.3 dated 16-May-2008, available from the
Moschip web site (registration required).

This patch is based on an earlier patch [1] for the SYBA 6x serial
port card by Ira W. Snyder.

[1]: http://www.gossamer-threads.com/lists/linux/kernel/1162435Signed-off-by: NEric Smith <eric@brouhaha.com>
Cc: stable <stable@kernel.org>
Signed-off-by: NGreg Kroah-Hartman <gregkh@suse.de>

Since commit e0626e38 (spi: prefix modalias with "spi:"),
the spi modalias is prefixed with "spi:".

This patch adds "spi:" prefix and removes "-spi" suffix in the modalias.
Signed-off-by: NAxel Lin <axel.lin@gmail.com>
Cc: stable <stable@kernel.org>
Signed-off-by: NGreg Kroah-Hartman <gregkh@suse.de>

reflect new static uart platform ids introduced by patch
http://article.gmane.org/gmane.linux.kernel/1126105Signed-off-by: NNikolaus Voss <n.voss@weinmann.de>
Signed-off-by: NGreg Kroah-Hartman <gregkh@suse.de>

It would have been nice if Intermec had supplied a PNP0501 _CID for the
COM3 device, but they didn't, so we have to recognize it explicitly.

Reference: https://bugzilla.kernel.org/show_bug.cgi?id=40612
CC: Jeff Chua <jeff.chua.linux@gmail.com>
Signed-off-by: NBjorn Helgaas <bhelgaas@google.com>
Cc: stable <stable@kernel.org>
Acked-by: NAlan Cox <alan@linux.intel.com>
Signed-off-by: NGreg Kroah-Hartman <gregkh@suse.de>

drivers/tty/serial/ucc_uart.c: In function 'qe2cpu_addr':
drivers/tty/serial/ucc_uart.c:238:2: warning: format '%x' expects type 'unsigned int', but argument 3 has type 'dma_addr_t'
Signed-off-by: NKumar Gala <galak@kernel.crashing.org>
Acked-by: NTimur Tabi <timur@freescale.com>
Signed-off-by: NGreg Kroah-Hartman <gregkh@suse.de>

Currently, PCIe bus number is set as fixed value "2".
However, PCIe bus number is not always "2".
This patch sets bus number using probe() parameter.
Signed-off-by: NTomoya MORINAGA <tomoya-linux@dsn.okisemi.com>
Signed-off-by: NGreg Kroah-Hartman <gregkh@suse.de>

drivers/tty/serial/samsung.c: In function 's3c24xx_serial_init':
drivers/tty/serial/samsung.c:1237: error: lvalue required as unary '&' operand

Cc: Greg Kroah-Hartman <gregkh@suse.de>
Signed-off-by: NKukjin Kim <kgene.kim@samsung.com>
Signed-off-by: NGreg Kroah-Hartman <gregkh@suse.de>

Commit d006199e72a9 ("serial: sh-sci: Regtype probing doesn't need to be
fatal.") made sci_init_single() return when sci_probe_regmap() succeeds,
although it should return when sci_probe_regmap() fails.  This causes
systems using the serial sh-sci driver to crash during boot.

Fix the problem by using the right return condition.
Signed-off-by: NRafael J. Wysocki <rjw@sisk.pl>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

of_alias_get_id() is broken and being reverted.  Remove the reference
to it and replace with a single incrementing id number.

There is no risk of regression here on the imx driver since the imx
change to use of_alias_get_id() is commit 22698aa2, "serial/imx: add
device tree probe support" which is new for v3.1, and it won't get
used unless CONFIG_OF is enabled and the board is booted using a
device tree.  A single incrementing integer is sufficient for now.
Signed-off-by: NGrant Likely <grant.likely@secretlab.ca>
Acked-by: NShawn Guo <shawn.guo@linaro.org>

It adds device tree probe support for imx tty/serial driver.
Signed-off-by: NJeremy Kerr <jeremy.kerr@canonical.com>
Signed-off-by: NJason Liu <jason.hui@linaro.org>
Signed-off-by: NShawn Guo <shawn.guo@linaro.org>
Cc: Sascha Hauer <s.hauer@pengutronix.de>
Cc: Alan Cox <alan@linux.intel.com>
Cc: Cc: Greg Kroah-Hartman <gregkh@suse.de>
Cc: Grant Likely <grant.likely@secretlab.ca>
Acked-by: NGrant Likely <grant.likely@secretlab.ca>

The patch removes all the uses of cpu_is_mx1().  Instead, it uses
the .id_table of platform_driver to distinguish the uart device type,
IMX1_UART and IMX21_UART.  The IMX21_UART type runs on all i.mx
except i.mx1.

A couple of !cpu_is_mx1 logic gets turned into is_imx21_uart,
as the codes wrapped there are really IMX21 type uart specific.

It also removes macro MX1_UCR3_REF25 and MX1_UCR3_REF30 which are
not used anywhere.
Signed-off-by: NShawn Guo <shawn.guo@linaro.org>
Cc: Sascha Hauer <s.hauer@pengutronix.de>
Cc: Alan Cox <alan@linux.intel.com>
Cc: Greg Kroah-Hartman <gregkh@suse.de>
Acked-by: NGrant Likely <grant.likely@secretlab.ca>

This allows us to move duplicated code in <asm/atomic.h>
(atomic_inc_not_zero() for now) to <linux/atomic.h>
Signed-off-by: NArun Sharma <asharma@fb.com>
Reviewed-by: NEric Dumazet <eric.dumazet@gmail.com>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: David Miller <davem@davemloft.net>
Cc: Eric Dumazet <eric.dumazet@gmail.com>
Acked-by: NMike Frysinger <vapier@gentoo.org>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Uart port is registered as a console during the driver's probe.
So explict registration of console with console_initcall is
removed.
Signed-off-by: NThomas Abraham <thomas.ab@samsung.com>
[kgene.kim@samsung.com: removed changes of s3c2400 and s3c24a0]
Signed-off-by: NKukjin Kim <kgene.kim@samsung.com>

For some reason I didn't notice the failure in my test builds,
probably lacking caffeine or something...
Signed-off-by: NBenjamin Herrenschmidt <benh@kernel.crashing.org>

Add poll_get_char and poll_put_char for kdb. Enable kdb at boot with:

kgdboc=hvc0

or at runtime with:

echo hvc0 > /sys/module/kgdboc/parameters/kgdboc
Signed-off-by: NAnton Blanchard <anton@samba.org>
Signed-off-by: NBenjamin Herrenschmidt <benh@kernel.crashing.org>

commit 4d2bb3f5 (powerpc/pseries: Re-implement HVSI as part of
hvc_vio) changed udbg_getc to be based on hvterm_raw_get_chars.
Unfortunately hvterm_raw_get_chars returns -EAGAIN if you ask
for anything less than 16 characters. As a result xmon no longer
accepts input and prints a stream of junk to the screen.

The recent change highlights a problem that xmon on pseries VIO
has had all along, that it can drop input characters. The issue
is the hypervisor call does not take a count argument and can
return up to 16 characters.

This patch adds a per vterm buffer that we copy input data into
and give it out as requested.
Signed-off-by: NAnton Blanchard <anton@samba.org>
Signed-off-by: NBenjamin Herrenschmidt <benh@kernel.crashing.org>

Currently, the hvc_console_print() function drops console output if the
hvc backend's put_chars() returns 0.  This patch changes this behavior
to allow a retry through returning -EAGAIN.

This change also affects the hvc_push() function.  Both functions are
changed to handle -EAGAIN and to retry the put_chars() operation.

If a hvc backend returns -EAGAIN, the retry handling differs:

  - hvc_console_print() spins to write the complete console output.
  - hvc_push() behaves the same way as for returning 0.

Now hvc backends can indirectly control the way how console output is
handled through the hvc console layer.
Signed-off-by: NHendrik Brueckner <brueckner@linux.vnet.ibm.com>
Acked-by: NAnton Blanchard <anton@samba.org>
Cc: <stable@kernel.org>
Signed-off-by: NBenjamin Herrenschmidt <benh@kernel.crashing.org>

On Tue, 28 Jun 2011, Ben Dooks wrote:

> On Tue, Jun 28, 2011 at 11:22:57PM +0200, Arnd Bergmann wrote:
>
> > On a related note, what about mach-s3c2400? It seems to be even more
> > incomplete.
>
> Probably the same fate awaits that. It is so old that there's little
> incentive to do anything with it.

So out it goes as well.

The PORT_S3C2400 definition in include/linux/serial_core.h is left there
to prevent a reuse of the same number for another port type.
Signed-off-by: NNicolas Pitre <nicolas.pitre@linaro.org>
Acked-by: NArnd Bergmann <arnd@arndb.de>

Commit bcae8aeb "[ARM] S3C24A0: Initial architecture support files"
brought in a bunch of files while explicitly leaving out the corresponding
Kconfig entry, stating that the series is not complete.

More than 2.5 years later, the support for this has not seen any progress.
This is therefore dead code.  If someone wants to revive this code, it is
always possible to retrieve it from the Git repository.
Signed-off-by: NNicolas Pitre <nicolas.pitre@linaro.org>
Acked-by: NBen Dooks <ben-linux@fluff.org>
Acked-by: NArnd Bergmann <arnd@arndb.de>

Acked-by: NGreg Kroah-Hartman <gregkh@suse.de>
Signed-off-by: NGrant Likely <grant.likely@secretlab.ca>

This workaround aims to break the deadlock situation
which raises during continuous transfer of data for long
duration over uart with hardware flow control. It is
observed that CTS interrupt cannot be cleared in uart
interrupt register (ICR). Hence further transfer over
uart gets blocked.

It is seen that during such deadlock condition ICR
don't get cleared even on multiple write. This leads
pass_counter to decrease and finally reach zero. This
can be taken as trigger point to run this UART_BT_WA.

Workaround backups the register configuration, does soft
reset of UART using BIT-0 of PRCC_K_SOFTRST_SET/CLEAR
registers and restores the registers.

This patch also provides support for uart init and exit
function calls if present.
Signed-off-by: NShreshtha Kumar Sahu <shreshthakumar.sahu@stericsson.com>
Signed-off-by: NLinus Walleij <linus.walleij@linaro.org>
Signed-off-by: NGreg Kroah-Hartman <gregkh@suse.de>

FCS could be GSM0_SOF, so will break state machine...

[This byte isn't quoted in any way so a SOF here doesn't imply an error
 occurred.]
Signed-off-by: NAlek Du <alek.du@intel.com>
Signed-off-by: NAlan Cox <alan@linux.intel.com>
Cc: stable <stable@kernel.org> [3.0]

[Trivial but best backported once its in 3.1rc I think]
Signed-off-by: NGreg Kroah-Hartman <gregkh@suse.de>

Signed-off-by: NAlexander Stein <alexander.stein@systec-electronic.com>
Reviewed-by: NJesper Juhl <jj@chaosbits.net>
Signed-off-by: NGreg Kroah-Hartman <gregkh@suse.de>

Signed-off-by: NAlexander Stein <alexander.stein@systec-electronic.com>
Signed-off-by: NGreg Kroah-Hartman <gregkh@suse.de>

In s3c24xx_serial_console_setup function, if the uart port that is
being setup as a console has not been initialized, an error can be
returned instead of using uart port 0 as the default console port.
The uart port that was intended to be used as a console could be
initialized at a later point during boot and then registered as a
console. This will avoid using uart port 0 as a unintended console
port.
Signed-off-by: NThomas Abraham <thomas.ab@samsung.com>
Signed-off-by: NKukjin Kim <kgene.kim@samsung.com>

Simplifies the code a bit and drops a few lines.
Signed-off-by: NGrant Likely <grant.likely@secretlab.ca>
Acked-by: NArnd Bergmann <arnd@arndb.de>

Unthrottling the TTY during close ends up enabling interrupts
on a device not on the active list, which will never have the
interrupts cleared.  Doctor, it hurts when I do this.

>>> On 6/2/2011 at 01:56 AM, in message <20110601145608.3e586e16@bob.linux.org.uk>, Alan Cox <alan@linux.intel.com> wrote:
> On Wed, 01 Jun 2011 10:34:07 +1200
> "andrew mcgregor" <andrew.mcgregor@alliedtelesis.co.nz> wrote:
> > The LKML message
> > http://kerneltrap.org/mailarchive/linux-kernel/2010/2/25/4541847 from
> > February doesn't seem to have been resolved since.  We struck the
> > issue, and the patch below (against 2.6.32) fixes it.  Should I
> > supply a patch against 3.0.0rc?
>
> I think that would be sensible. I don't actually see how you hit it as
> the IRQ ought to be masked by then but it's certainly wrong for n_tty
> to be calling into check_unthrottle at that point.
>
> So yes please send a patch with a suitable Signed-off-by: line to
> linux-serial and cc GregKH <greg@kroah.com> as well.
>
> Alan
Signed-off-by: NAndrew McGregor <andrew.mcgregor@alliedtelesis.co.nz>
Signed-off-by: NGreg Kroah-Hartman <gregkh@suse.de>

This patch "modernize" tty/serial/samsung.c to use non-legacy code for
suspend/resume.
Signed-off-by: NMyungJoo Ham <myungjoo.ham@samsung.com>
Signed-off-by: NKyungMin Park <kyungmin.park@samsung.com>
Signed-off-by: NGreg Kroah-Hartman <gregkh@suse.de>

Kconfig allows enabling console support for the SC26xx driver even when
it's configured as a module resulting in a:

ERROR: "uart_console_device" [drivers/tty/serial/sc26xx.ko] undefined!

modpost error since the driver was merged in
eea63e0e [SC26XX: New serial driver for
SC2681 uarts] in 2.6.25.  Fixed by only allowing console support to be
enabled if the driver is builtin.
Signed-off-by: NRalf Baechle <ralf@linux-mips.org>
Cc: linux-serial@vger.kernel.org
Cc: linux-kernel@vger.kernel.org
Cc: linux-mips@linux-mips.org
Cc: stable <stable@kernel.org>
Acked-by: NAlan Cox <alan@linux.intel.com>
Signed-off-by: NGreg Kroah-Hartman <gregkh@suse.de>

The driver went to initialize its waitqueue at the start of the main processing
thread. However, it is possible that this thread is not scheduled on a CPU
before the write function is called which leads to a following error:

 BUG: spinlock bad magic on CPU#1, swapper/1
  lock: f5f3ebdc, .magic: 00000000, .owner: <none>/-1, .owner_cpu: 0
 Pid: 1, comm: swapper Not tainted 3.0.0-rc2+ #67
 Call Trace:
  [<c1289663>] spin_bug+0xa3/0xf0
  [<c12897ad>] do_raw_spin_lock+0x7d/0x150
  [<c1490006>] ? init_idle+0x8d/0x20c
  [<c14963de>] _raw_spin_lock_irqsave+0x4e/0x60
  [<c102f2bb>] ? __wake_up+0x1b/0x50
  [<c102f2bb>] __wake_up+0x1b/0x50
  [<c12d03bc>] ? uart_console_write+0x4c/0x60
  [<c12d36c0>] ? serial_m3110_enable_ms+0x10/0x10
  [<c12d3715>] serial_m3110_con_write+0x55/0x60
  [<c1041575>] __call_console_drivers+0x75/0x90
  [<c10415d9>] _call_console_drivers+0x49/0x80
  [<c1041baa>] console_unlock+0xca/0x1f0
  [<c10420ef>] vprintk+0x18f/0x4f0
  [<c10787cb>] ? trace_hardirqs_on+0xb/0x10
  [<c14928a3>] printk+0x18/0x1a
  [<c1042730>] register_console+0x2e0/0x350
  [<c12d098e>] uart_add_one_port+0x33e/0x3d0
  [<c10787cb>] ? trace_hardirqs_on+0xb/0x10
  [<c103e10b>] ? try_to_wake_up+0x18b/0x250
  [<c1485ba6>] serial_m3110_probe+0x1c2/0x1df
  [<c12d3d20>] ? serial_m3110_suspend+0x40/0x40
  [<c1303db7>] spi_drv_probe+0x17/0x20
  ...

We fix this by initializing the waitqueue before the main thread is created.
Signed-off-by: NMika Westerberg <mika.westerberg@linux.intel.com>
Signed-off-by: NAlan Cox <alan@linux.intel.com>
Signed-off-by: NGreg Kroah-Hartman <gregkh@suse.de>

Change print message to notice instead of error to clean up
non critcal messages showing on startup. The MAX3111 not being present
is a normal path for end user systems.
Signed-off-by: NWilliam Douglas <william.douglas@intel.com>
[rebased on 3.0, switched to dev_dbg()]
Signed-off-by: NAlan Cox <alan@linux.intel.com>
Signed-off-by: NGreg Kroah-Hartman <gregkh@suse.de>

This patch addes delay loop on fifo reset function for UART.
On high speed freq, it needs delay function when fifo reset.
If not, system will hang by this uart reset problem when resuming
from suspend mode.
Signed-off-by: NJongpill Lee <boyko.lee@samsung.com>
Signed-off-by: NJaecheol Lee <jc.lee@samsung.com>
Signed-off-by: NKukjin Kim <kgene.kim@samsung.com>
Signed-off-by: NGreg Kroah-Hartman <gregkh@suse.de>

Commit 4539c24f "tty/serial: Add
explicit PORT_TEGRA type" introduced separate flags describing the need
for IER bits UUE and RTOIE. Both bits are required for the XSCALE port
type. While that patch updated uart_config[] as required, the auto-probing
code wasn't updated to set the RTOIE flag when an XSCALE port type was
detected. This caused such ports to stop working. This patch rectifies
that.
Reported-by: NSebastian Andrzej Siewior <bigeasy@linutronix.de>
Tested-by: NSebastian Andrzej Siewior <bigeasy@linutronix.de>
Signed-off-by: NStephen Warren <swarren@nvidia.com>
Cc: stable <stable@kernel.org> [3.0]
Signed-off-by: NGreg Kroah-Hartman <gregkh@suse.de>

This doesn't cause any real bugs, but it should still be fixed.
Signed-off-by: NMike Frysinger <vapier@gentoo.org>
Signed-off-by: NGreg Kroah-Hartman <gregkh@suse.de>

Since the printk_ratelimit() shouldn't be used anymore (see comment in
include/linux/printk.h), replace it with printk_ratelimited().
Signed-off-by: NManuel Zerpies <manuel.f.zerpies@ww.stud.uni-erlangen.de>
Signed-off-by: NGreg Kroah-Hartman <gregkh@suse.de>

The gsm_mux is created/destroyed when ldisc is
opened/closed but clients of the MUX channel devices (gsmttyN)
may access this structure as long as the TTYs are open.
For the open, the ldisc open is guaranteed to preceed the TTY open,
but the close has no such guaranteed ordering. As a result,
the gsm_mux can be freed in the ldisc close before being accessed
by one of the TTY clients. This can happen if the ldisc is removed
while there are open, active MUX channels.
A similar situation exists for DLCI-0, it is basically a resource
shared by MUX and DLCI  , and should not be freed while they can
be accessed

To avoid this, gsm_mux and dlcis now have a reference counter
ldisc open takes a reference on the mux and all the dlcis
gsmtty_open takes a reference on the mux, dlci0 and its specific
dlci. Dropping the last reference initiates the actual free.
Signed-off-by: NRuss Gorby <russ.gorby@intel.com>
Acked-by: NAlan Cox <alan@linux.intel.com>
Signed-off-by: NGreg Kroah-Hartman <gregkh@suse.de>

This patch adds the ability to open a network data connection over a mux
virtual tty channel. This is for modems that support data connections
with raw IP frames instead of PPP. On high speed data connections this
eliminates a significant amount of PPP overhead. To use this interface,
the application must first tell the modem to open a network connection on
a virtual tty. Once that has been accomplished, the app will issue an
IOCTL on that virtual tty to create the network interface. The IOCTL will
return the index of the interface created.

The two IOCTL commands are:

    ioctl( fd, GSMIOC_ENABLE_NET );

    ioctl( fd, GSMIOC_DISABLE_NET );
Signed-off-by: NRuss Gorby <russ.gorby@intel.com>
Acked-by: NAlan Cox <alan@linux.intel.com>
Signed-off-by: NGreg Kroah-Hartman <gregkh@suse.de>

The n_gsm driver being an ldisc, does not provide a convenient method
e.g. udev to create the tty device nodes automatically when the ldisc
is opened.

The TTY device nodes are now created via calls to tty_register_device
from the ldisc open.
Signed-off-by: NRuss Gorby <russ.gorby@intel.com>
Signed-off-by: NGreg Kroah-Hartman <gregkh@suse.de>