At tty hangup, the line discipline instance is reinitialized by
closing the current ldisc instance and opening a new instance.
This operation is complicated by error recovery: if the attempt
to reinit the current line discipline fails, the line discipline
is reset to N_TTY (which should not but can fail).

Re-purpose tty_ldisc_reinit() to return a valid, open line discipline
instance, or otherwise, an error.
Signed-off-by: NPeter Hurley <peter@hurleysoftware.com>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

tty->ldisc is a ptr to struct tty_ldisc, but unfortunately 'ldisc' is
also used as a parameter or local name to refer to the line discipline
index value (ie, N_TTY, N_GSM, etc.); instead prefer the name used
by the line discipline registration/ref counting functions.
Signed-off-by: NPeter Hurley <peter@hurleysoftware.com>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

In preparation for destroying the line discipline instance on hangup,
move tty_ldisc_kill() to eliminate needless forward declarations.
No functional change.
Signed-off-by: NPeter Hurley <peter@hurleysoftware.com>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

In preparation of destroying line discipline on hangup, fix
ldisc core operations to properly handle when the tty's ldisc is
NULL.
Signed-off-by: NPeter Hurley <peter@hurleysoftware.com>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

tty file_operations (read/write/ioctl) wait for the ldisc reference
indefinitely (until ldisc lifetime events, such as hangup or TIOCSETD,
finish). Since hangup now destroys the ldisc and does not instance
another copy, file_operations must now be prepared to receive a NULL
ldisc reference from tty_ldisc_ref_wait():

CPU 0                                   CPU 1
-----                                   -----
(*f_op->read)() => tty_read()
                                        __tty_hangup()
                                        ...
                                        f_op = &hung_up_tty_fops;
                                        ...
                                        tty_ldisc_hangup()
                                           tty_ldisc_lock()
                                           tty_ldisc_kill()
                                              tty->ldisc = NULL
                                           tty_ldisc_unlock()
ld = tty_ldisc_ref_wait()
/* ld == NULL */

Instead, the action taken now is to return the same value as if the
tty had been hungup a moment earlier:

CPU 0                                   CPU 1
-----                                   -----
                                        __tty_hangup()
                                        ...
                                        f_op = &hung_up_tty_fops;
(*f_op->read)() => hung_up_tty_read()
return 0;
                                        ...
                                        tty_ldisc_hangup()
                                           tty_ldisc_lock()
                                           tty_ldisc_kill()
                                              tty->ldisc = NULL
                                           tty_ldisc_unlock()
Signed-off-by: NPeter Hurley <peter@hurleysoftware.com>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

tty_ldisc_kill() sets tty->ldisc to NULL; _not_ to N_TTY with a valid
but unopened ldisc. Fix function header documentation.
Signed-off-by: NPeter Hurley <peter@hurleysoftware.com>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

tty_ldisc_get() returns ERR_PTR() values if unsuccessful, not NULL;
fix function header documentation.
Signed-off-by: NPeter Hurley <peter@hurleysoftware.com>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

After the ldisc is released, but before the tty is destroyed, the termios
is saved (in tty_free_termios()); this termios is restored if a new
tty is created on next open(). However, the line discipline is always
reset, which is not obvious in the current method. Instead, reset
as part of the restore.

Restore the original line discipline, which may not have been N_TTY.
Signed-off-by: NPeter Hurley <peter@hurleysoftware.com>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

The chars_in_buffer() line discipline method serves no functional
purpose, other than as a (dubious) debugging aid for mostly bit-rotting
drivers. Despite being documented as an optional method, every caller
is unconditionally executed (although conditionally compiled).
Furthermore, direct tty->ldisc access without an ldisc ref is unsafe.
Lastly, N_TTY's chars_in_buffer() has warned of removal since 3.12.
Signed-off-by: NPeter Hurley <peter@hurleysoftware.com>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

As the #warning indicates, the open-coded ldisc reset was always not ok.
Not only is this code long dead, but now it would have no effect as
the ldisc is destroyed when this driver's close() method returns; remove.
Signed-off-by: NPeter Hurley <peter@hurleysoftware.com>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

Extract the driver lookup and reopen-or-initialize logic into helper
function tty_open_by_driver(). No functional change.
Signed-off-by: NPeter Hurley <peter@hurleysoftware.com>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

Evaluate the conditions which prevent this tty being the controlling
terminal in one place, just before setting the controlling terminal.
Signed-off-by: NPeter Hurley <peter@hurleysoftware.com>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

The tty lock/unlock code does not belong in the special lockfunc section
which is treated specially by stack backtraces.
Signed-off-by: NPeter Hurley <peter@hurleysoftware.com>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

The tty core invokes the optional driver shutdown() just before
the optional driver remove() (shutdown() has access to the termios
and remove() does not). Because pty drivers must prevent the default
remove() action, the Unix98 pty drivers define a dummy remove() function.

Instead, release the slave index in the remove() method and delete the
optional shutdown() method.
Signed-off-by: NPeter Hurley <peter@hurleysoftware.com>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

tty_driver_remove_tty() is only local-scope; declare as static.
Signed-off-by: NPeter Hurley <peter@hurleysoftware.com>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

tty_init_termios() never returns an error; re-declare as void. Remove
unnecessary error handling from callers. Remove extern declarations
of tty_free_termios() and free_tty_struct() and re-declare in file
scope.
Signed-off-by: NPeter Hurley <peter@hurleysoftware.com>
Acked-by: NJohan Hovold <johan@kernel.org>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

free_tty_struct() is never called with NULL tty; the two call sites
would already have faulted on earlier access.
Signed-off-by: NPeter Hurley <peter@hurleysoftware.com>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

release_tty() leaks the ldisc instance when called directly (rather
than when releasing the file descriptor from tty_release()).

Since tty_ldisc_release() clears tty->ldisc, releasing the ldisc
instance at tty teardown if tty->ldisc is non-null is not in danger
of double-releasing the ldisc.

Remove deinitialize_tty_struct() now that free_tty_struct() always
performs the tty_ldisc_deinit().
Signed-off-by: NPeter Hurley <peter@hurleysoftware.com>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

Although n_tty_check_unthrottle() has a valid ldisc reference (since
the tty core gets the ldisc ref in tty_read() before calling the line
discipline read() method), it does not have a valid ldisc reference to
the "other" pty of a pty pair. Since getting an ldisc reference for
tty->link essentially open-codes tty_wakeup(), just replace with the
equivalent tty_wakeup().

Cc: <stable@vger.kernel.org>
Signed-off-by: NPeter Hurley <peter@hurleysoftware.com>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

ioctl(TIOCGETD) retrieves the line discipline id directly from the
ldisc because the line discipline id (c_line) in termios is untrustworthy;
userspace may have set termios via ioctl(TCSETS*) without actually
changing the line discipline via ioctl(TIOCSETD).

However, directly accessing the current ldisc via tty->ldisc is
unsafe; the ldisc ptr dereferenced may be stale if the line discipline
is changing via ioctl(TIOCSETD) or hangup.

Wait for the line discipline reference (just like read() or write())
to retrieve the "current" line discipline id.

Cc: <stable@vger.kernel.org>
Signed-off-by: NPeter Hurley <peter@hurleysoftware.com>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

A small window exists where a tty reopen will observe the tty
just prior to imminent teardown (tty->count == 0); in this case, open()
returns EIO to userspace.

Instead, retry the open after checking for signals and yielding;
this interruptible retry loop allows teardown to commence and initialize
a new tty on retry. Never retry the BSD master pty reopen; there is no
guarantee the pty pair teardown is imminent since the slave file
descriptors may remain open indefinitely.
Signed-off-by: NPeter Hurley <peter@hurleysoftware.com>
Cc: stable <stable@vger.kernel.org> # 4.4
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

Allow a signal to interrupt the wait for a tty reopen; eg., if
the tty has starting final close and is waiting for the device to
drain.
Signed-off-by: NPeter Hurley <peter@hurleysoftware.com>
Cc: stable <stable@vger.kernel.org> # 4.4
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

In commit c39dfebc ("drivers/tty/serial:
make serial/atmel_serial.c explicitly non-modular") we removed the code
relating to modular support since it currently only supports built in.

However, when redoing my build coverage for mips allmodconfig, which
sets CONFIG_OF, I noticed a remaining line that needs to be removed,
else we will get a build failure for an undefined module macro.

Unfortunately this didn't appear for any of the other arch I tested
more frequently, such as ARM.

Since MODULE_DEVICE_TABLE is a no-op for non-modular code, we can just
remove the offending line.

Fixes: c39dfebc ("drivers/tty/serial: make serial/atmel_serial.c explicitly non-modular")
Cc: Nicolas Ferre <nicolas.ferre@atmel.com>
Cc: Jiri Slaby <jslaby@suse.com>
Reported-by: NSudip Mukherjee <sudip@vectorindia.org>
Signed-off-by: NPaul Gortmaker <paul.gortmaker@windriver.com>
Acked-by: NNicolas Ferre <nicolas.ferre@atmel.com>
Acked-by: NSudip Mukherjee <sudip@vectorindia.org>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

The BSP team noticed that there is spin/mutex lock issue on sh-sci when
CPUFREQ is used.  The issue is that the notifier function may call
mutex_lock() while the spinlock is held, which can lead to a BUG().
This may happen if CPUFREQ is changed while another CPU calls
clk_get_rate().

Taking the spinlock was added to the notifier function in commit
e552de24 ("sh-sci: add platform device private data"), to
protect the list of serial ports against modification during traversal.
At that time the Common Clock Framework didn't exist yet, and
clk_get_rate() just returned clk->rate without taking a mutex.
Note that since commit d535a230 ("serial: sh-sci: Require a
device per port mapping."), there's no longer a list of serial ports to
traverse, and taking the spinlock became superfluous.

To fix the issue, just remove the cpufreq notifier:
  1. The notifier doesn't work correctly: all it does is update stored
     clock rates; it does not update the divider in the hardware.
     The divider will only be updated when calling sci_set_termios().
     I believe this was broken back in 2004, when the old
     drivers/char/sh-sci.c driver (where the notifier did update the
     divider) was replaced by drivers/serial/sh-sci.c (where the
     notifier just updated port->uartclk).
     Cfr. full-history-linux commits 6f8deaef2e9675d9 ("[PATCH] sh: port
     sh-sci driver to the new API") and 3f73fe878dc9210a ("[PATCH]
     Remove old sh-sci driver").
  2. On modern SoCs, the sh-sci parent clock rate is no longer related
     to the CPU clock rate anyway, so using a cpufreq notifier is
     futile.
Signed-off-by: NGeert Uytterhoeven <geert+renesas@glider.be>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

The 8250_of never compiled since in the Kconfig we have SERIAL_OF_PLATFORM
but in the makefile we expect to have SERIAL_8250_OF...

When the 8250_of.c is actually compiled we will have two errors:
missing linux/nwpserial.h and 8250/8250.h.
Fix those as well at the same time when enable the compilation of the
driver.
Signed-off-by: NPeter Ujfalusi <peter.ujfalusi@ti.com>
Fixes: afd7f88f ("serial: 8250: move of_serial code to 8250 directory")
Reported-by: NGuenter Roeck <linux@roeck-us.net>
CC: Arnd Bergmann <arnd@arndb.de>
Acked-by: NArnd Bergmann <arnd@arndb.de>
Acked-by: NJon Hunter <jonathanh@nvidia.com>
Tested-by: NJon Hunter <jonathanh@nvidia.com>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

Instead of defining a new field in the uart_amba_port structure, use the
existing iotype field of the uart_port structure, which is intended for
this purpose.  If we need to use 32-bit register access, we set iotype
to UPIO_MEM32, otherwise we set it to UPIO_MEM.

For early console, specify the "mmio32" option on the kernel command-line.
Example:

        earlycon=pl011,mmio32,0x3ced1000
Signed-off-by: NTimur Tabi <timur@codeaurora.org>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

The REG_x macros are indices into a table, not register offsets.  Since earlycon
does not have access to the vendor data, we can currently only support standard
ARM PL011 devices.
Signed-off-by: NRussell King <rmk+kernel@arm.linux.org.uk>
Tested-by: NHuang Shijie <shijie.huang@arm.com>
Signed-off-by: NTimur Tabi <timur@codeaurora.org>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

Commit 984d74a7 ("sysrq: rcu-ify __handle_sysrq") replaced
spin_lock_irqsave() calls with rcu_read_lock() calls in sysrq. Since
rcu_read_lock() does not disable preemption, faulthandler_disabled() in
__do_page_fault() in x86/fault.c returns false. When the code later calls
might_sleep() in the pagefault handler, we get the following warning:

BUG: sleeping function called from invalid context at ../arch/x86/mm/fault.c:1187
in_atomic(): 0, irqs_disabled(): 0, pid: 4706, name: bash
Preemption disabled at:[<ffffffff81484339>] printk+0x48/0x4a

To fix this, we release the RCU read lock before we crash.

Tested this patch on linux 3.18 by booting off one of our boards.

Fixes: 984d74a7 ("sysrq: rcu-ify __handle_sysrq")
Signed-off-by: NAni Sinha <ani@arista.com>
Reviewed-by: NRik van Riel <riel@redhat.com>
Signed-off-by: NPaul E. McKenney <paulmck@linux.vnet.ibm.com>

When sysrq is triggered from console, serial driver for SUN hypervisor
console receives a console break and enables the sysrq. It expects a valid
sysrq char following with break. Meanwhile if driver receives 'NULL'
ASCII char then it disables sysrq and sysrq handler will never be invoked.

This fix skips calling uart sysrq handler when 'NULL' is received while
sysrq is enabled.
Signed-off-by: NVijay Kumar <vijay.ac.kumar@oracle.com>
Acked-by: NKarl Volz <karl.volz@oracle.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Constifies sunhv_ops structures in tty's serial
driver since they are not modified after their
initialization.

Detected and found using Coccinelle.
Suggested-by: NJulia Lawall <Julia.Lawall@lip6.fr>
Signed-off-by: NAya Mahfouz <mahfouz.saif.elyazal@gmail.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

ls1 has qe and ls1 has arm cpu.
move qe from arch/powerpc to drivers/soc/fsl
to adapt to powerpc and arm
Signed-off-by: NZhao Qiang <qiang.zhao@freescale.com>
Signed-off-by: NScott Wood <scottwood@freescale.com>

All platforms that used to define an sci_fck clock have now switched to
the fck name. Remove the fallback code.
Signed-off-by: NLaurent Pinchart <laurent.pinchart+renesas@ideasonboard.com>
Acked-by: NSimon Horman <horms+renesas@verge.net.au>
Signed-off-by: NGeert Uytterhoeven <geert+renesas@glider.be>
Acked-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

Add support for using the Baud Rate Generator for External Clock (BRG), as
found on some SCIF and HSCIF variants, to provide the sampling clock.
This can improve baud rate range and accuracy.
Signed-off-by: NGeert Uytterhoeven <geert+renesas@glider.be>
Acked-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

Add support for using the SCIx clock pin "(H)SCK" as an external clock
input on (H)SCI(F), providing the sampling clock.

Note that this feature is not yet supported on the select SCIFA variants
that also have it (e.g. sh7723, sh7724, and r8a7740).

On (H)SCIF variants with an External Baud Rate Generator (BRG), the
BRG Clock Select Register must be configured for the external clock.
Signed-off-by: NGeert Uytterhoeven <geert+renesas@glider.be>
Acked-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

Refactor the clock and baud rate parameter code to ease adding support
for multiple sampling clock sources.
sci_scbrr_calc() now returns the bit rate error, so it can be compared
to the bit rate error using other sampling clock sources.
Signed-off-by: NGeert Uytterhoeven <geert+renesas@glider.be>
Acked-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

The "renesas,scif" compatible value is currently used for the SCIF
variant in all Renesas SoCs of the R-Car family.  However, the variant
used in the R-Car family is not the common "SH-4(A)" variant, but a
derivative with added "Baud Rate Generator for External Clock" (BRG),
which is also present in sh7734.

Use the family-specific SCIF compatible values for R-Car Gen1, Gen2, and
Gen3 SoCs to differentiate.  The "renesas,scif" compatible value can
still be used as a common denominator for SCIF variants with the
"SH-4(A)" register layout (i.e. ignoring the "Serial Extension Mode
Register" (SCEMR) and the new BRG-specific registers).
Signed-off-by: NGeert Uytterhoeven <geert+renesas@glider.be>
Acked-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

The "renesas,scif" compatible value is currently used for the SCIF
variant in all Renesas SoCs of the R-Car and RZ families.  However, the
variant used in the RZ family is not the common "SH-4(A)" variant, but
the "SH-2(A) with FIFO data count register" variant, as it has the
"Serial Extension Mode Register" (SCEMR), just like on sh7203, sh7263,
sh7264, and sh7269.

Use the (already documented) SoC-specific "renesas,scif-r7s72100"
compatible value to differentiate.  The "renesas,scif" compatible value
can still be used as a common denominator for SCIF variants with the
"SH-4(A)" register layout (i.e. ignoring the SCEMR register).
Note that currently both variants are treated the same, but this may
change if support for the SCEMR register is ever added.
Signed-off-by: NGeert Uytterhoeven <geert+renesas@glider.be>
Reviewed-by: NLaurent Pinchart <laurent.pinchart+renesas@ideasonboard.com>
Acked-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

Store the encoded port and register types directly in of_device_id.data,
instead of using a pointer to a structure.
This saves memory and simplifies the source code, especially when adding
more compatible entries later.
Signed-off-by: NGeert Uytterhoeven <geert+renesas@glider.be>
Reviewed-by: NLaurent Pinchart <laurent.pinchart+renesas@ideasonboard.com>
Acked-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

Add register definitions for the Baud Rate Generator for External Clock
(BRG), as found in some SCIF and in HSCIF, including a new regtype for
the "SH-4(A)"-derived SCIF variant with BRG.
Signed-off-by: NGeert Uytterhoeven <geert+renesas@glider.be>
Acked-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

The maximum baud rate depends on the sampling rate.
HSCIF has a variable sampling rate and sets s->sampling_rate to zero,
hence use the minimum sampling rate of 8.
Signed-off-by: NGeert Uytterhoeven <geert+renesas@glider.be>
Reviewed-by: NLaurent Pinchart <laurent.pinchart+renesas@ideasonboard.com>
Acked-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>