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Commit Graph

142 Commits

Author SHA1 Message Date
Denys Vlasenko
f4581cab8d serial_core: Deinline uart_update_mctrl, save 304 bytes
This function compiles to 92 bytes of machine code.

Signed-off-by: Denys Vlasenko <dvlasenk@redhat.com>
CC: Jiri Slaby <jslaby@suse.com>
CC: linux-serial@vger.kernel.org
Reviewed-by: Peter Hurley <peter@hurleysoftware.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2015-12-13 19:59:48 -08:00
Peter Hurley
cc2aaabfd6 tty: Remove tty_port::close_wait
With the removal of tty_wait_until_sent_from_close(), tty drivers
no longer wait during open for parallel closes to complete (instead,
the tty core waits before calling the driver open() method). Thus,
the close_wait waitqueue is no longer used for waiting.

Remove struct tty_port::close_wait.

Signed-off-by: Peter Hurley <peter@hurleysoftware.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2015-10-17 21:11:29 -07:00
Max Filippov
d215d80957 serial_core: support native endianness
There are three natural ways in which devices may be wired to the system:
little endian (device receives correctly ordered bits of a word written
by little-endian CPU to its register, but big-endian CPU needs to swap
bytes of a word before writing it), big endian (same, but with big-endian
CPU in more favourable position) and native endian (CPU of either
endianness may do word-sized I/O without need for byteswapping).

Adding an option for native endianness allows using single kernel command
line for boards with native-endian serial ports on bi-endian
architectures. This goes in parallel with 'native-endian' DTS attribute.

Signed-off-by: Max Filippov <jcmvbkbc@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2015-10-04 19:11:05 +01:00
Peter Hurley
9e31364fc3 serial: core: Remove tty port activate() and shutdown() methods
serial core does not use tty_port_open() or tty_port_close(); serial
core defines and extends it's own tty open() and close() methods
(uart_open() and uart_close(), respectively).

Remove the tty_port activate() and shutdown() initializations, and
the uart_port_activate() function, which is never called.

NB: uart_port_shutdown() is used by uart_close() => uart_shutdown()
call chain (but not via the tty_port methods).

Signed-off-by: Peter Hurley <peter@hurleysoftware.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2015-08-04 22:07:23 -07:00
Peter Hurley
6fb98fb303 serial: core: Use proper spinlock flavor in uart_close()
uart_close() runs in non-atomic context only; use
spin_lock/unlock_irq instead of saving the interrupt state (which
== on).

Signed-off-by: Peter Hurley <peter@hurleysoftware.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2015-08-04 22:07:22 -07:00
Peter Hurley
e144c58cad serial: core: Fix crashes while echoing when closing
While closing, new rx data may be received after the input buffers
have been flushed but before stop_rx() halts receiving [1]. The
new data might not be processed by flush_to_ldisc() until after
uart_shutdown() and normal input processing is re-enabled (ie.,
tty->closing = 0). The race is outlined below:

CPU 0                         | CPU 1
                              |
uart_close()                  |
   tty_port_close_start()     |
      tty->closing = 1        |
      tty_ldisc_flush()       |
                              | => IRQ
                              |   while (LSR & data ready)
                              |      uart_insert_char()
                              |   tty_flip_buffer_push()
                              | <= EOI
   stop_rx()                  |   .
   uart_shutdown()            |   .
      free xmit.buf           |   .
   tty_port_tty_set(NULL)     |   .
   tty->closing = 0           |   .
                              | flush_to_ldisc()
                              |   n_tty_receive_buf_common()
                              |      __receive_buf()
                              |         ...
                              |         commit_echoes()
                              |            uart_flush_chars()
                              |               __uart_start()
                              | ** OOPS on port.tty deref **
   tty_ldisc_flush()          |

Input processing must be prevented from echoing (tty->closing = 1)
until _after_ the input buffers have been flushed again at the end
of uart_close().

[1] In fact, some input may actually be buffered _after_ stop_rx()
since the rx interrupt may have already triggered but not yet been
handled when stop_rx() disables rx interrupts.

Fixes: 2e75891083 ("serial: core: Flush ldisc after dropping port
mutex in uart_close()")
Reported-by: Robert Elliott <elliott@hp.com>
Signed-off-by: Peter Hurley <peter@hurleysoftware.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2015-07-23 18:08:28 -07:00
Joakim Nordell
f10a223321 serial: core: cleanup in uart_get_baud_rate()
Align with coding guidelines:
Replaced a chain of "else if" by a switch case.

Signed-off-by: Joakim Nordell <joakim.nordell@intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2015-06-12 17:34:36 -07:00
Noam Camus
6e63be3fee serial: earlycon: Add support for big-endian MMIO accesses
Support command line parameters of the form:
earlycon=<name>,io|mmio|mmio32|mmio32be,<addr>,<options>

This commit seem to be needed even after commit:
serial: 8250: Add support for big-endian MMIO accesses
c627f2ceb6

Signed-off-by: Noam Camus <noamc@ezchip.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2015-06-01 06:55:12 +09:00
Rasmus Villemoes
429b474990 tty: remove buf parameter from tty_name()
tty_name no longer uses the buf parameter, so remove it along with all
the 64 byte stack buffers that used to be passed in.

Mostly generated by the coccinelle script

@depends on patch@
identifier buf;
constant C;
expression tty;
@@
- char buf[C];
  <+...
- tty_name(tty, buf)
+ tty_name(tty)
  ...+>

allmodconfig compiles, so I'm fairly confident the stack buffers
weren't used for other purposes as well.

Signed-off-by: Rasmus Villemoes <linux@rasmusvillemoes.dk>
Reviewed-by: Peter Hurley <peter@hurleysoftware.com>
Acked-by: Jesper Nilsson <jesper.nilsson@axis.com>
Acked-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2015-05-06 22:26:57 +02:00
Peter Hurley
10afbe346b serial: core: Fix kernel-doc build warnings
Fix uart_console_write() kernel-doc build warnings.

Warning(drivers/tty/serial/serial_core.c:1778): No description found for parameter 'putchar'
Warning(drivers/tty/serial/serial_core.c:1778): Excess function parameter 'write' description in 'uart_console_write'

Fixes: 1cfe42b7fd ("serial: core: Fix kernel doc for uart_console_write()")
Reported-by: Fengguang Wu <fengguang.wu@intel.com>
Signed-off-by: Peter Hurley <peter@hurleysoftware.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2015-04-28 14:26:21 +02:00
Peter Hurley
1cfe42b7fd serial: core: Fix kernel doc for uart_console_write()
'/**' is required to start a kernel-doc comment block.

Acked-by: Rob Herring <robh@kernel.org>
Signed-off-by: Peter Hurley <peter@hurleysoftware.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2015-03-26 16:16:20 +01:00
Peter Hurley
959801fef9 serial: core: Add minor field to uart_port
UART drivers that share ttyS namespace cannot trivially compute the
ttyS index from the port->line value since the minor_start may be
offset from minor 64. Further, to do so requires a pointer to the
uart driver since there is no back pointer from uart_port to
uart_driver.

Rather than have UART drivers computing the minor value by themselves,
encapsulate within the serial core at port registration time.

Signed-off-by: Peter Hurley <peter@hurleysoftware.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2015-03-26 16:10:11 +01:00
Peter Hurley
73abaf87f0 serial: earlycon: Refactor parse_options into serial core
Prepare to support console-defined matching; refactor the command
line parameter string processing from parse_options() into a
new core function, uart_parse_earlycon(), which decodes command line
parameters of the form:
   earlycon=<name>,io|mmio|mmio32,<addr>,<options>
   console=<name>,io|mmio|mmio32,<addr>,<options>
   earlycon=<name>,0x<addr>,<options>
   console=<name>,0x<addr>,<options>

Signed-off-by: Peter Hurley <peter@hurleysoftware.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2015-03-07 03:55:07 +01:00
Fabian Frederick
97f9f707d2 serial: core: replace current->state by __set_current_state()
Use helper functions to access current->state.
Direct assignments are prone to races and therefore buggy.

Thanks to Peter Zijlstra for the exact definition of the problem.

Suggested-By: Peter Zijlstra <peterz@infradead.org>
Signed-off-by: Fabian Frederick <fabf@skynet.be>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2015-03-07 03:08:42 +01:00
Peter Hurley
391f93f2ec serial: core: Rework hw-assisted flow control support
hw-assisted flow control support was added to the serial core
in v3.8 with commits,
dba05832cb ("SERIAL: core: add hardware assisted h/w flow control support")
2cbacafd7a ("SERIAL: core: add hardware assisted s/w flow control support")
9aba8d5b01 ("SERIAL: core: add throttle/unthrottle callbacks for hardware
                assisted flow control")
Since then, additional requirements for serial core support have arisen.
Specifically,
1. Separate tx and rx flow control settings for UARTs which only support
   tx flow control (ie., autoCTS).
2. Disable sw-assisted CTS flow control in autoCTS mode
3. Support for RTS flow control by serial core and userspace in autoRTS mode

Distinguish mode from capability; introduce UPSTAT_AUTORTS, UPSTAT_AUTOCTS
and UPSTAT_AUTOXOFF which, when set by the uart driver, enable serial core
support for hw-assisted rx, hw-assisted tx and hw-assisted in-band/IXOFF
rx flow control, respectively. [Note: hw-assisted in-band/IXON tx flow
control does not require serial core support/intervention and can be
enabled by the uart driver when required.]

These modes must be set/reset in the driver's set_termios() method, based
on termios settings, and thus can be safely queried in any context in which
one of the port lock, port mutex or termios rwsem are held. Set these modes
in the 2 in-tree drivers, omap-serial and 8250_omap, which currently
use UPF_HARD_FLOW/UPF_SOFT_FLOW support.

Retain UPF_HARD_FLOW and UPF_SOFT_FLOW as capabilities; re-define
UPF_HARD_FLOW as both UPF_AUTO_RTS and UPF_AUTO_CTS to allow for distinct
and separate rx and tx flow control capabilities.

Disable sw-assisted CTS flow control when UPSTAT_AUTOCTS is enabled.

Signed-off-by: Peter Hurley <peter@hurleysoftware.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2015-02-02 10:11:28 -08:00
Peter Hurley
b164c9721e serial: core: Simplify console suspend logic in uart_suspend_port()
When the uart port being suspended is a console and consoles are
not suspending (kernel command line contains no_console_suspend),
then no action is performed for that port, and the function can
return early.

If the function has not returned early, then one of the conditions
is not true, so the expression
   (console_suspend_enabled || !uart_console(uport))
must be true and can be eliminated.

Similarly, the expression
   (console_suspend_enabled && uart_console(uport))
simplifies to just uart_console(uport).

Signed-off-by: Peter Hurley <peter@hurleysoftware.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2015-02-02 10:11:27 -08:00
James Bottomley
68ed7e1c3d serial: fix parisc boot hang
This is a partial revert of 2f2dafe (serial: serial_core.c: printk
replacement) which gets us booting again.  The real problem seems to be
the _emit path in early boot.  However, until we can root cause it, we
need at least to get boot working.

Fixes: 2f2dafe77d
Cc: stable@vger.kernel.org
Signed-off-by: James Bottomley <JBottomley@Parallels.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2015-01-02 12:19:28 -08:00
Kevin Cernekee
3ffb1a8193 serial: core: Add big-endian iotype
Since most drivers interpret UPIO_MEM32 to mean "little-endian" and use
readl/writel to access the registers, add a parallel UPIO_MEM32BE to
request the use of big-endian MMIO accessors (ioread32be/iowrite32be).

Signed-off-by: Kevin Cernekee <cernekee@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2014-11-25 17:06:40 -08:00
Ricardo Ribalda Delgado
bd737f8738 tty/serial_core: Introduce lock mechanism for RS485
Introduce an homogeneous lock system between setting and using the rs485
data of the uart_port.

This patch should not be split into multiple ones in order to avoid
leaving the tree in an unstable state.

Acked-by: Nicolas Ferre <nicolas.ferre@atmel.com>
Reviewed-by: Alan Cox <alan@linux.intel.com>
Suggested-by: Alan Cox <alan@linux.intel.com>
Cc: Nicolas Ferre <nicolas.ferre@atmel.com>
Cc: Jiri Slaby <jslaby@suse.cz>
Cc: One Thousand Gnomes <gnomes@lxorguk.ukuu.org.uk>
Signed-off-by: Ricardo Ribalda Delgado <ricardo.ribalda@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2014-11-06 15:00:44 -08:00
Ricardo Ribalda Delgado
a9c20a9cf3 serial_core: Remove call to driver-specific TIO[GS]RS485]
Once there is no more handlers for TIOC[GS]RS485 there is no need to
call the driver specific ioctl when the generic implementation is
missing.

Reviewed-by: Alan Cox <alan@linux.intel.com>
Cc: Jiri Slaby <jslaby@suse.cz>
Signed-off-by: Ricardo Ribalda Delgado <ricardo.ribalda@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2014-11-06 15:00:20 -08:00
Ricardo Ribalda Delgado
a5f276f10f serial_core: Handle TIOC[GS]RS485 ioctls.
The following drivers: 8250_core, atmel_serial, max310x, mcf, omap-serial
and sci16is7xx implement code to handle RS485 ioctls.

In order to avoid code duplication, we implement a simple ioctl handler
on the serial_core layer.

This handler can be used by all the other drivers instead of duplicating
code.

Until this is the only RS485 ioctl handler, it will try first the
rs485_config callback and if it is not present it will call the driver
specific ioctl.

Reviewed-by: Alan Cox <alan@linux.intel.com>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Jiri Slaby <jslaby@suse.cz>
Signed-off-by: Ricardo Ribalda Delgado <ricardo.ribalda@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2014-11-06 14:58:53 -08:00
Peter Hurley
732a84a037 serial: core: Pass termios to set_ldisc() notifications
UART drivers which enable modem status interrupts when switching
to N_PPS line discipline need to determine if modem status
interrupts should be disabled when switching from N_PPS.
Specifically, the set_ldisc() notification needs to evaluate
UART_ENABLE_MS() which requires termios->c_cflag.

Convert in-tree UART drivers to new interface.

Signed-off-by: Peter Hurley <peter@hurleysoftware.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2014-11-06 14:57:27 -08:00
Peter Hurley
db1b9dfcd6 serial: core: Claim port mutex for set_ldisc()
Three UART drivers (8250, atmel & amba-pl010) enable modem status
interrupts if the line discipline is changed to N_PPS. However,
the uart port flags may only be safely modified while holding the
port mutex.

Signed-off-by: Peter Hurley <peter@hurleysoftware.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2014-11-06 14:57:27 -08:00
Greg Kroah-Hartman
28e1445c65 Merge branch 'tty-linus' into 'tty-testing'
We need the fixes in drivers/tty/tty_io.c that were done in there for
future patches in this branch.

Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2014-11-05 19:43:23 -08:00
Peter Hurley
91b32f5413 serial: core: Fix port count when uart_open() errors
A port count mismatch occurs if mutex_lock_interruptible()
exits uart_open() and the port has already been opened. This may
prematurely close a port on an open tty. Since uart_close() is _always_
called if uart_open() fails, the port count must be corrected if errors
occur.

Always increment the port count in uart_open(), regardless of errors;
always decrement the port count in uart_close(). Note that
tty_port_close_start() decrements the port count when uart_open()
was successful.

Signed-off-by: Peter Hurley <peter@hurleysoftware.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2014-11-05 18:53:55 -08:00
Peter Hurley
64dbee3105 serial: core: Remove extra locking in uart_write()
uart_start() only claims the port->lock to call __uart_start(),
which does the actual processing. Eliminate the extra acquire/release
in uart_write(); call __uart_start() directly with port->lock already
held.

Signed-off-by: Peter Hurley <peter@hurleysoftware.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2014-11-05 18:53:55 -08:00
Peter Hurley
2b702b9b68 serial: core: Colocate crucial structure linkage
The key function of uart_add_one_port() is to cross-reference the
UART driver's port structure with the serial core's state table;
keep the assignments together and document this crucial association.

Signed-off-by: Peter Hurley <peter@hurleysoftware.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2014-11-05 18:53:55 -08:00
Peter Hurley
1f0afd1607 serial: core: Remove redundant timeout assignments
tty_port_init() initializes close_delay and closing_wait to these
same values; remove.

Signed-off-by: Peter Hurley <peter@hurleysoftware.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2014-11-05 18:53:55 -08:00
Peter Hurley
74866e7593 serial: core: Unwrap >80 char line in uart_close()
The wrapped line looks wrong and out-of-place; leave it as
>80 char line.

Signed-off-by: Peter Hurley <peter@hurleysoftware.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2014-11-05 18:53:55 -08:00
Peter Hurley
7c8ab967e3 serial: Fix locking for uart driver set_termios() method
The low-level uart driver may modify termios settings to override
settings that are not compatible with the uart, such as CRTSCTS.
Thus, callers of the low-level uart driver's set_termios() method must
hold termios_rwsem write lock to prevent concurrent access to termios,
in case such override occurs.

The termios_rwsem lock requirement does not extend to console setup
(ie., uart_set_options), as console setup cannot race with tty
operations. Nor does this lock requirement extend to functions which
cannot be concurrent with tty ioctls (ie., uart_port_startup() and
uart_resume_port()).

Further, always claim the port mutex to protect hardware
re-reprogramming in the set_termios() uart driver method. Note this
is unnecessary for console initialization in uart_set_options()
which cannot be concurrent with other uart operations.

Signed-off-by: Peter Hurley <peter@hurleysoftware.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2014-11-05 18:53:54 -08:00
Peter Hurley
2e75891083 serial: core: Flush ldisc after dropping port mutex in uart_close()
The tty buffers (and any line discipline buffers) must be flushed after
the UART hardware has shutdown; otherwise, a racing open on the same
tty may receive data from the previous session, which is a security
hazard. However, holding the port mutex while flushing the line
discipline buffers creates a lock inversion if the set_termios()
handler takes the port mutex (as it does in the followup patch,
'serial: Fix locking for uart driver set_termios method'.

Flush the ldisc buffers after dropping the port mutex; the tty lock
is still held which prevents a concurrent open() from advancing while
flushing. Since no new rx data is possible after uart_shutdown() until
a new open reinitializes the port, the later flush has no impact on
what data is being discarded.

Signed-off-by: Peter Hurley <peter@hurleysoftware.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2014-11-05 18:53:54 -08:00
Peter Hurley
479e9b94fd serial: Refactor uart_flush_buffer() from uart_close()
In the context of the final tty & port close, flushing the tx
ring buffer after the hardware has already been shutdown and
the ring buffer freed is neither required nor desirable.

uart_flush_buffer() performs 3 operations:
1. Resets tx ring buffer indices, but the tx ring buffer has
   already been freed and the indices are reset if the port is
   re-opened.
2. Calls uart driver's flush_buffer() method
   5 in-tree uart drivers define flush_buffer() methods:
     amba-pl011, atmel-serial, imx, serial-tegra, timbuart
   These have been refactored into the shutdown() method, if
   required.
3. Kicks the ldisc for more writing, but this is undesirable.
   The file handle is being released; any waiting writer will
   will be kicked out by tty_release() with a warning. Further,
   the N_TTY ldisc may generate SIGIO for a file handle which
   is no longer valid.

Cc: Nicolas Ferre <nicolas.ferre@atmel.com>
Cc: Russell King <linux@arm.linux.org.uk>
Cc: Laxman Dewangan <ldewangan@nvidia.com>
Signed-off-by: Peter Hurley <peter@hurleysoftware.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2014-11-05 18:53:54 -08:00
Peter Hurley
91f189de46 serial: Fix sparse warnings in uart_throttle()/uart_unthrottle()
The struct uart_port.flags field is type upf_t, as are the matching
bit definitions. Change local mask variable to type upf_t.

Fixes sparse warnings:
drivers/tty/serial/serial_core.c:620:22: warning: invalid assignment: |=
drivers/tty/serial/serial_core.c:620:22:    left side has type unsigned int
drivers/tty/serial/serial_core.c:620:22:    right side has type restricted upf_t
drivers/tty/serial/serial_core.c:622:22: warning: invalid assignment: |=
drivers/tty/serial/serial_core.c:622:22:    left side has type unsigned int
drivers/tty/serial/serial_core.c:622:22:    right side has type restricted upf_t
drivers/tty/serial/serial_core.c:624:17: warning: restricted upf_t degrades to integer
drivers/tty/serial/serial_core.c:626:22: warning: invalid assignment: &=
drivers/tty/serial/serial_core.c:626:22:    left side has type unsigned int
drivers/tty/serial/serial_core.c:626:22:    right side has type restricted upf_t
drivers/tty/serial/serial_core.c:629:20: warning: restricted upf_t degrades to integer
drivers/tty/serial/serial_core.c:632:20: warning: restricted upf_t degrades to integer
drivers/tty/serial/serial_core.c:643:22: warning: invalid assignment: |=
drivers/tty/serial/serial_core.c:643:22:    left side has type unsigned int
drivers/tty/serial/serial_core.c:643:22:    right side has type restricted upf_t
drivers/tty/serial/serial_core.c:645:22: warning: invalid assignment: |=
drivers/tty/serial/serial_core.c:645:22:    left side has type unsigned int
drivers/tty/serial/serial_core.c:645:22:    right side has type restricted upf_t
drivers/tty/serial/serial_core.c:647:17: warning: restricted upf_t degrades to integer
drivers/tty/serial/serial_core.c:649:22: warning: invalid assignment: &=
drivers/tty/serial/serial_core.c:649:22:    left side has type unsigned int
drivers/tty/serial/serial_core.c:649:22:    right side has type restricted upf_t
drivers/tty/serial/serial_core.c:652:20: warning: restricted upf_t degrades to integer
drivers/tty/serial/serial_core.c:655:20: warning: restricted upf_t degrades to integer

Signed-off-by: Peter Hurley <peter@hurleysoftware.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2014-11-05 16:15:43 -08:00
Peter Hurley
d4260b5169 serial: Fix upstat_t sparse warnings
Commit 299245a145,
serial: core: Privatize modem status enable flags, introduced
the upstat_t type and matching bit definitions. The purpose is to
produce sparse warnings if the wrong bit definitions are used
(by warning of implicit integer conversions).

Fix implicit conversion to integer return type from uart_cts_enabled()
and uart_dcd_enabled().

Fixes the following sparse warnings:
drivers/tty/serial/serial_core.c:63:30: warning: incorrect type in return expression (different base types)
drivers/tty/serial/serial_core.c:63:30:    expected int
drivers/tty/serial/serial_core.c:63:30:    got restricted upstat_t
include/linux/serial_core.h:364:30: warning: incorrect type in return expression (different base types)
include/linux/serial_core.h:364:30:    expected bool
include/linux/serial_core.h:364:30:    got restricted upstat_t
include/linux/serial_core.h:364:30: warning: incorrect type in return expression (different base types)
include/linux/serial_core.h:364:30:    expected bool
include/linux/serial_core.h:364:30:    got restricted upstat_t

Reported-by: Fengguang Wu <fengguang.wu@intel.com>
Signed-off-by: Peter Hurley <peter@hurleysoftware.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2014-11-05 16:15:43 -08:00
Peter Hurley
547039ec50 serial: Fix divide-by-zero fault in uart_get_divisor()
uart_get_baud_rate() will return baud == 0 if the max rate is set
to the "magic" 38400 rate and the SPD_* flags are also specified.
On the first iteration, if the current baud rate is higher than the
max, the baud rate is clamped at the max (which in the degenerate
case is 38400). On the second iteration, the now-"magic" 38400 baud
rate selects the possibly higher alternate baud rate indicated by
the SPD_* flag. Since only two loop iterations are performed, the
loop is exited, a kernel WARNING is generated and a baud rate of
0 is returned.

Reproducible with:
 setserial /dev/ttyS0 spd_hi base_baud 38400

Only perform the "magic" 38400 -> SPD_* baud transform on the first
loop iteration, which prevents the degenerate case from recognizing
the clamped baud rate as the "magic" 38400 value.

Reported-by: Robert Święcki <robert@swiecki.net>
Cc: <stable@vger.kernel.org> # all
Signed-off-by: Peter Hurley <peter@hurleysoftware.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2014-11-05 16:14:09 -08:00
Greg Kroah-Hartman
69784fa539 Revert "serial/core: Initialize the console pm state"
This reverts commit a86713b153.

Kevin Hilman writes:

	Multiple boot failures on ARM[1] were bisected down to this
	patch.

	How was this patch tested, and on which platforms?

	Also, the changelog states that this should be done only for
	UART_CAP_SLEEP, but the patch does it for every UART.

	Greg, I suggest this patch be dropped from tty-next until it has
	been better described and tested.

	[1] http://lists.linaro.org/pipermail/kernel-build-reports/2014-October/005550.html

Reported-by: Kevin Hilman <khilman@kernel.org>
Cc: Sudhir Sreedharan <ssreedharan@mvista.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2014-10-02 21:33:50 -07:00
Sudhir Sreedharan
a86713b153 serial/core: Initialize the console pm state
For console devices having UART_CAP_SLEEP capability, the uart_pm_state has
to be initialized to UART_PM_STATE_ON. Otherwise the LCR regiser values
are reinitialized when uart_change_pm is called from uart_configure_port.

Signed-off-by: Sudhir Sreedharan <ssreedharan@mvista.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2014-09-28 21:49:48 -04:00
Peter Hurley
938f7e13b5 serial: core: Use spin_lock_irq() in uart_set_termios()
uart_set_termios() is called with interrupts enabled; no need to
save and restore the interrupt state when taking the uart port lock.

Signed-off-by: Peter Hurley <peter@hurleysoftware.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2014-09-23 21:19:35 -07:00
Peter Hurley
d01f4d181c serial: core: Privatize tty->hw_stopped
tty->hw_stopped is not used by the tty core and is thread-unsafe;
hw_stopped is a member of a bitfield whose fields are updated
non-atomically and no lock is suitable for serializing updates.

Replace serial core usage of tty->hw_stopped with uport->hw_stopped.
Use int storage which works around Alpha EV4/5 non-atomic byte storage,
since uart_port uses different locks to protect certain fields within the
structure.

Signed-off-by: Peter Hurley <peter@hurleysoftware.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2014-09-23 21:19:35 -07:00
Peter Hurley
299245a145 serial: core: Privatize modem status enable flags
The serial core uses the tty port flags, ASYNC_CTS_FLOW and
ASYNC_CD_CHECK, to track whether CTS and DCD changes should be
ignored or handled. However, the tty port flags are not safe for
atomic bit operations and no lock provides serialized updates.

Introduce the struct uart_port status field to track CTS and DCD
enable states, and serialize access with uart port lock. Substitute
uart_cts_enabled() helper for tty_port_cts_enabled().

Signed-off-by: Peter Hurley <peter@hurleysoftware.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2014-09-23 21:19:35 -07:00
Peter Hurley
4d90bb147e serial: core: Document and assert lock requirements for irq helpers
The serial core provides two helper functions, uart_handle_dcd_change()
and uart_handle_cts_change(), for UART drivers to use at interrupt
time. The serial core expects the UART driver to hold the uart port lock
when calling these helpers to prevent state corruption.

If lockdep enabled, trigger a warning if the uart port lock is not held
when calling these helper functions.

Signed-off-by: Peter Hurley <peter@hurleysoftware.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2014-09-23 21:19:34 -07:00
Peter Hurley
c993257bf7 serial: core: Unwrap tertiary assignment in uart_handle_dcd_change()
Prepare for spin lock assertion; move non-trivial assignment into
function body.

Signed-off-by: Peter Hurley <peter@hurleysoftware.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2014-09-08 16:23:36 -07:00
Peter Hurley
fba594a848 serial: core: Remove unsafe x_char optimization
uart_unthrottle() attempts to avoid sending START and the previous
x_char if the previous x_char has not yet been sent. However, this
optimization could leave the sender in a throttled state; for example,
if the sender is throttled and this unthrottle coincides with a manual
tcflow(TCION) from user-space, then neither START would be sent.

Signed-off-by: Peter Hurley <peter@hurleysoftware.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2014-09-08 16:22:42 -07:00
Peter Hurley
c235ccc1c4 serial: core: Fix x_char race
The UART driver is expected to clear port->x_char after
transmission while holding the port->lock. However, the serial
core fails to take the port->lock before assigning port->xchar.
This allows for the following race

CPU 0                         |  CPU 1
                              |
                              | serial8250_handle_irq
                              |   ...
                              |   serial8250_tx_chars
                              |     if (port->x_char)
                              |       serial_out(up, UART_TX, port->x_char)
uart_send_xchar               |
  port->x_char = ch           |
                              |       port->x_char = 0
  port->ops->start_tx()       |
                              |

The x_char on CPU 0 will never be sent.

Take the port->lock in uart_send_xchar() before assigning port->x_char.

Signed-off-by: Peter Hurley <peter@hurleysoftware.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2014-09-08 16:22:42 -07:00
Peter Hurley
99abf3b924 serial: Style fix
Unwrap if() conditional; no functional change.

Signed-off-by: Peter Hurley <peter@hurleysoftware.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2014-09-08 16:21:35 -07:00
Peter Hurley
a6eec92ec0 Revert "serial: uart: add hw flow control support configuration"
This reverts commit 06aa82e498.
This commit purports to enable auto CTS flow control for the 8250
UART driver. However, the 8250 UART driver already supports auto
CTS flow control via UART_CAP_AFE and UART_CAP_EFR. Indeed, this
patch introduces another DT attribute for which an existing firmware
flag already exists ("auto-flow-control"). Furthermore, the use of
UPF_HARD_FLOW requires the UART driver to define .throttle and
.unthrottle methods, neither of which are defined for the 8250 UART
driver (which will result in a NULL ptr dereference). Finally, this patch
supposes to fix existing bugs in the serial core for auto CTS-enabled
hardware, but does not include the class of hardware for which these
bugs exist.

CC: Murali Karicheri <m-karicheri2@ti.com>
CC: Rob Herring <robh+dt@kernel.org>
Signed-off-by: Peter Hurley <peter@hurleysoftware.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2014-09-08 16:21:35 -07:00
Sudip Mukherjee
2f2dafe77d serial: serial_core.c: printk replacement
printk replaced with corresponding dev_* .
fixed two broken user-visible strings used by the corresponding printk.
the null check for uport->dev and port->dev is removed as dev_* will check for
null while printing.
printing of dev_name(uport->dev) and dev_name(port->dev) also removed as those
are being printed by dev_* .

Signed-off-by: Sudip Mukherjee <sudip@vectorindia.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2014-09-08 15:34:15 -07:00
Linus Torvalds
ae36e95cf8 The branch contains the following device tree changes the v3.17 merge
window:
 
 Group changes to the device tree. In preparation for adding device tree
 overlay support, OF_DYNAMIC is reworked so that a set of device tree
 changes can be prepared and applied to the tree all at once. OF_RECONFIG
 notifiers see the most significant change here so that users always get
 a consistent view of the tree. Notifiers generation is moved from before
 a change to after it, and notifiers for a group of changes are emitted
 after the entire block of changes have been applied
 
 Automatic console selection from DT. Console drivers can now use
 of_console_check() to see if the device node is specified as a console
 device. If so then it gets added as a preferred console. UART devices
 get this support automatically when uart_add_one_port() is called.
 
 DT unit tests no longer depend on pre-loaded data in the device tree.
 Data is loaded dynamically at the start of unit tests, and then unloaded
 again when the tests have completed.
 
 Also contains a few bugfixes for reserved regions and early memory setup.
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Merge tag 'devicetree-for-linus' of git://git.secretlab.ca/git/linux

Pull device tree updates from Grant Likely:
 "The branch contains the following device tree changes the v3.17 merge
  window:

  Group changes to the device tree.  In preparation for adding device
  tree overlay support, OF_DYNAMIC is reworked so that a set of device
  tree changes can be prepared and applied to the tree all at once.
  OF_RECONFIG notifiers see the most significant change here so that
  users always get a consistent view of the tree.  Notifiers generation
  is moved from before a change to after it, and notifiers for a group
  of changes are emitted after the entire block of changes have been
  applied

  Automatic console selection from DT.  Console drivers can now use
  of_console_check() to see if the device node is specified as a console
  device.  If so then it gets added as a preferred console.  UART
  devices get this support automatically when uart_add_one_port() is
  called.

  DT unit tests no longer depend on pre-loaded data in the device tree.
  Data is loaded dynamically at the start of unit tests, and then
  unloaded again when the tests have completed.

  Also contains a few bugfixes for reserved regions and early memory
  setup"

* tag 'devicetree-for-linus' of git://git.secretlab.ca/git/linux: (21 commits)
  of: Fixing OF Selftest build error
  drivers: of: add automated assignment of reserved regions to client devices
  of: Use proper types for checking memory overflow
  of: typo fix in __of_prop_dup()
  Adding selftest testdata dynamically into live tree
  of: Add todo tasklist for Devicetree
  of: Transactional DT support.
  of: Reorder device tree changes and notifiers
  of: Move dynamic node fixups out of powerpc and into common code
  of: Make sure attached nodes don't carry along extra children
  of: Make devicetree sysfs update functions consistent.
  of: Create unlocked versions of node and property add/remove functions
  OF: Utility helper functions for dynamic nodes
  of: Move CONFIG_OF_DYNAMIC code into a separate file
  of: rename of_aliases_mutex to just of_mutex
  of/platform: Fix of_platform_device_destroy iteration of devices
  of: Migrate of_find_node_by_name() users to for_each_node_by_name()
  tty: Update hypervisor tty drivers to use core stdout parsing code.
  arm/versatile: Add the uart as the stdout device.
  of: Enable console on serial ports specified by /chosen/stdout-path
  ...
2014-08-14 09:53:39 -06:00
Yoshihiro YUNOMAE
c2b703b807 serial/core: Fix too big allocation for attribute member
Current code allocates too much data for tty_groups member of uart_port struct,
so fix it.

Signed-off-by: Yoshihiro YUNOMAE <yoshihiro.yunomae.ez@hitachi.com>
Reported-by: Dan Carpenter <dan.carpenter@oracle.com>
Reviewed-by: Daniel Thompson <daniel.thompson@linaro.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2014-07-23 18:56:17 -07:00
Greg Kroah-Hartman
266dcff03e Serial: allow port drivers to have a default attribute group
Some serial drivers (like 8250), want to add sysfs files.  We need to do
so in a race-free way, so allow any port to be able to specify an
attribute group that should be added at device creation time.

Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Yoshihiro YUNOMAE <yoshihiro.yunomae.ez@hitachi.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2014-07-17 18:21:21 -07:00