linux-toradex.git/include/linux/serial_8250.h, branch v4.1.1

serial: 8250: Decouple RSA probe

2015-03-26T17:18:20+00:00

Prepare for 8250 split; separate RSA probe and resource management
from base port operations. Override base port operations for the
config_port(), request_port() and release_port() methods to
implement the optional RSA probe and resource management only in
the universal/legacy 8250 driver.

Introduce 'probe' flags for 8250 ports, which allows drivers higher
up the driver stack to enable optional probes.

Signed-off-by: Peter Hurley 
Signed-off-by: Greg Kroah-Hartman

serial: 8250: Separate legacy irq handling from core port operations

2015-03-26T17:15:16+00:00

Prepare for 8250 split; decouple irq setup/teardown and handler from
core port operations.

Introduce setup_irq() and release_irq() 8250 driver methods; the 8250
core will use these methods to install and remove irq handling for
the given 8250 port.

Refactor irq chain linking/unlinking from 8250 core into
univ8250_setup_irq()/univ8250_release_irq() for the universal 8250 driver.

Signed-off-by: Peter Hurley 
Signed-off-by: Greg Kroah-Hartman

serial: 8250_early: Remove setup_early_serial8250_console()

2015-03-26T16:25:27+00:00

setup_earlycon() will now match and register the desired earlycon
from the param string (as if 'earlycon=...' had been set on the
command line). Use setup_earlycon() from existing arch call sites
which start an earlycon directly.

Acked-by: Rob Herring 
Signed-off-by: Peter Hurley 
Signed-off-by: Greg Kroah-Hartman

console: Add extensible console matching

2015-03-26T15:16:20+00:00

Add match() method to struct console which allows the console to
perform console command line matching instead of (or in addition to)
default console matching (ie., by fixed name and index).

The match() method returns 0 to indicate a successful match; normal
console matching occurs if no match() method is defined or the
match() method returns non-zero. The match() method is expected to set
the console index if required.

Re-implement earlycon-to-console-handoff with direct matching of
"console=uart|uart8250,..." to the 8250 ttyS console.

Acked-by: Rob Herring 
Signed-off-by: Peter Hurley 
Signed-off-by: Greg Kroah-Hartman

serial: 8250: Use canary to restart console after suspend

2015-02-02T18:11:27+00:00

When using no_console_suspend, the serial console may be powered off
anyway during system sleep. Upon resume, the port may be in its default
power-on state, but is expected to continue console i/o before the device
has received its pm callback. The resultant garbage i/o can cause all
kinds of havoc on the remote end.

Use the scratch register as a canary to discover if the console
has been powered-off. Write a non-zero value to the scratch register
at port suspend and reprogram the port before any console i/o if the
scratch register != canary before port resume.

This workaround is disabled for omap_8250 (which uses different divisor
programming).

Credit to Doug Anderson  for the idea of using
the scratch register canary to discover port power-down.

Cc: Doug Anderson 
Signed-off-by: Peter Hurley 
Signed-off-by: Greg Kroah-Hartman

serial: omap_8250: Fix RTS handling

2015-01-09T22:10:46+00:00

The OMAP3 UART ignores MCR[1] (ie., UART_MCR_RTS) when in autoRTS
mode (UPF_HARD_FLOW + CRTSCTS). This makes it impossible for either
the serial core or userspace to manually flow control the sender.

Disable autoRTS mode when RTS is lowered and restore the previous
mode when RTS is raised.

Note that the OMAP3 UART provides no mechanism for switching from
autoRTS mode without corrupting incoming data; to access the
necessary register, the line control settings must be set to 8-e-2
and thus any data received during that time will be interpreted with
those settings. This corruption has been observed in practice.

Cc: Sebastian Andrzej Siewior 
Signed-off-by: Peter Hurley 
Signed-off-by: Greg Kroah-Hartman

serial/8250: Remove obsolete handling of rs485 ioctls

2014-11-06T22:59:21+00:00

There is no more users for this functions. All the 8250 drivers are
using the rs485 handler on serial_core instead.

Reviewed-by: Alan Cox 
Cc: Jiri Slaby 
Cc: Sebastian Andrzej Siewior 
Cc: Alan Cox 
Cc: Tony Lindgren 
Cc: Peter Hurley 
Cc: Yoshihiro YUNOMAE 
Cc: Andy Shevchenko 
Cc: Ingo Molnar 
Signed-off-by: Ricardo Ribalda Delgado 
Signed-off-by: Greg Kroah-Hartman

tty: serial: 8250: use 32bit variable for rpm_tx_active

2014-09-30T01:20:38+00:00

The kbuild test robot wrote me:
|  make.cross ARCH=powerpc
|>> ERROR: ".__xchg_called_with_bad_pointer" [drivers/tty/serial/8250/8250.ko] undefined!

The generic implementation of xchg() on arm and x86 works for variables of
size one bye (char). According to the report powerpc does not support
xchg() for one byte sized variables and looking further it seems also to
be the same case for sparc and tile (or for 10 out of 26 architectures
which provide a custom implementation).
For that reason I increase the size of the variable from one to four
bytes to get it work on powerpc (and the others).

Reported-By: kbuild test robot 
Signed-off-by: Sebastian Andrzej Siewior 
Signed-off-by: Greg Kroah-Hartman

tty: serial: 8250_core: add run time pm

2014-09-26T16:01:56+00:00

While comparing the OMAP-serial and the 8250 part of this I noticed that
the latter does not use run time-pm. Here are the pieces. It is
basically a get before first register access and a last_busy + put after
last access. This has to be enabled from userland _and_ UART_CAP_RPM is
required for this.
The runtime PM can usually work transparently in the background however
there is one exception to this: After serial8250_tx_chars() completes
there still may be unsent bytes in the FIFO (depending on CPU speed vs
baud rate + flow control). Even if the TTY-buffer is empty we do not
want RPM to disable the device because it won't send the remaining
bytes. Instead we leave serial8250_tx_chars() with RPM enabled and wait
for the FIFO empty interrupt. Once we enter serial8250_tx_chars() with
an empty buffer we know that the FIFO is empty and since we are not going
to send anything, we can disable the device.
That xchg() is to ensure that serial8250_tx_chars() can be called
multiple times and only the first invocation will actually invoke the
runtime PM function. So that the last invocation of __stop_tx() will
disable runtime pm.

NOTE: do not enable RPM on the device unless you know what you do! If
the device goes idle, it won't be woken up by incomming RX data _unless_
there is a wakeup irq configured which is usually the RX pin configure
for wakeup via the reset module. The RX activity will then wake up the
device from idle. However the first character is garbage and lost. The
following bytes will be received once the device is up in time. On the
beagle board xm (omap3) it takes approx 13ms from the first wakeup byte
until the first byte that is received properly if the device was in
core-off.

v5…v8:
	- drop RPM from serial8250_set_mctrl() it will be used in
	  restore path which already has RPM active and holds
	  dev->power.lock
v4…v5:
	- add a wrapper around rpm function and introduce UART_CAP_RPM
	  to ensure RPM put is invoked after the TX FIFO is empty.
v3…v4:
	- added runtime to the console code
	- removed device_may_wakeup() from serial8250_set_sleep()

Cc: mika.westerberg@linux.intel.com
Reviewed-by: Tony Lindgren 
Tested-by: Tony Lindgren 
Signed-off-by: Sebastian Andrzej Siewior 
Signed-off-by: Greg Kroah-Hartman

tty: serial: 8250_core: allow to overwrite & export serial8250_startup()

2014-09-08T23:32:36+00:00

The OMAP version of the 8250 can actually use 1:1 serial8250_startup().
However it needs to be extended by a wake up irq which should to be
requested & enabled at ->startup() time and disabled at ->shutdown() time.

v2…v3: properly copy callbacks
v1…v2: add shutdown callback

Acked-by: Alan Cox 
Signed-off-by: Sebastian Andrzej Siewior 
Signed-off-by: Greg Kroah-Hartman