linux-toradex.git/Documentation/gpio.txt, branch v3.4.76

Documentation/gpio.txt: Explain expected pinctrl interaction

2012-03-12T17:27:07+00:00

Update gpio.txt based on recent discussions regarding interaction with the
pinctrl subsystem.

Previously, gpio_request() was described as explicitly not performing any
required mux setup operations etc.

Now, gpio_request() is explicitly as explicitly performing any required mux
setup operations where possible. In the case it isn't, platform code is
required to have set up any required muxing or other configuration prior to
gpio_request() being called, in order to maintain the same semantics.

This is achieved by gpiolib drivers calling e.g. pinctrl_request_gpio() in
their .request() operation.

Cc: Randy Dunlap 
Cc: linux-doc@vger.kernel.org
Signed-off-by: Stephen Warren 
Reviewed-by: Linus Walleij 
Signed-off-by: Grant Likely

Documentation: gpio: Add details of open-drain/source configuration

2012-03-05T14:49:44+00:00

Adding details of open drain(open collector) and open source
(open emitter) configuration of the gpio so that client can
set the pin as open drain at the time of gpio request.

Signed-off-by: Laxman Dewangan 
Reviwed-by: Mark Brown 
Acked-by: Linus Walleij 
Signed-off-by: Grant Likely

Revert "gpiolib: annotate gpio-intialization with __must_check"

2011-01-14T01:26:46+00:00

This reverts commit 0fdae42d361bbb431ca0ab0efed5126a94821177, which
wasn't really supposed to go in, and causes lots of annoying warnings.

Quoth Andrew:
  "Complete brainfart - I meant to drop that patch ages ago."

Quoth Greg:
  "Ick, yeah, that patch isn't ok to go in as-is, all of the callers
   need to be fixed up first, which is what I thought we had agreed on..."

Reported-by: Stephen Rothwell 
Acked-by: Andrew Morton 
Acked-by: Greg KH 
Signed-off-by: Linus Torvalds

gpiolib: annotate gpio-intialization with __must_check

2011-01-13T16:03:14+00:00

Because GPIOs can have crucial functions especially in embedded systems,
we are better safe than sorry regarding their configuration.  For
gpio_request, the documentation is simply enforced: "The return
value of gpio_request() must be checked." For gpio_direction_* and
gpio_request_*, we now act accordingly.

Signed-off-by: Wolfram Sang 
Cc: David Brownell 
Cc: Greg KH 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

Documentation/gpio.txt: explain poll/select usage

2010-11-18T23:00:46+00:00

Add a bit more information how to use poll(2) on GPIO value files
correctly. For me it was not clear that I need to poll(2) for
POLLPRI|POLLERR or select(2) for exceptfds.

Signed-off-by: Bernhard Walle 
Signed-off-by: Randy Dunlap 
Signed-off-by: Linus Torvalds

gpio: doc updates

2010-09-10T01:57:24+00:00

There's been some recent confusion about error checking GPIO numbers.
briefly, it should be handled mostly during setup, when gpio_request() is
called, and NEVER by expectig gpio_is_valid to report more than
never-usable GPIO numbers.

[akpm@linux-foundation.org: terminate unterminated comment]
Signed-off-by: David Brownell 
Cc: Eric Miao" 
Cc: "Ryan Mallon" 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

gpiolib: decouple might_sleep_if() from DEBUG

2010-08-11T15:59:08+00:00

Be more consistent about runtime programming interface abuse warnings,
which can reduce some confusion and trigger bugfixes.  Based on an
observation and patch from Jani Nikula.

Also update doc to highlight some sleeping-call issues and to match some
recent changes.

Signed-off-by: David Brownell 
Cc: Jani Nikula 
Cc: "Ryan Mallon" 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

gpio: introduce gpio_request_one() and friends

2010-03-06T19:26:48+00:00

gpio_request() without initial configuration of the GPIO is normally
useless, introduce gpio_request_one() together with GPIOF_ flags for
input/output direction and initial output level.

gpio_{request,free}_array() for multiple GPIOs.

Signed-off-by: Eric Miao 
Cc: David Brownell 
Cc: Ben Nizette 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

gpiolib: add support for changing value polarity in sysfs

2009-12-16T15:20:01+00:00

Drivers may use gpiolib sysfs as part of their public user space
interface. The GPIO number and polarity might change from board to
board. The gpio_export_link() call can be used to hide the GPIO number
from user space. Add support for also hiding the GPIO line polarity
changes from user space.

Signed-off-by: Jani Nikula 
Cc: David Brownell 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

correct gpio.txt typos

2009-12-10T02:59:52+00:00

Corrected sysfs gpio chip node name and fixed punctuation.

Signed-off-by: Dominik D. Geyer 
Signed-off-by: Randy Dunlap 
Cc: David Brownell 
Signed-off-by: Linus Torvalds