14 Jan, 2011
2 commits
-
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 -
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
19 Nov, 2010
1 commit
-
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
10 Sep, 2010
1 commit
-
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
11 Aug, 2010
1 commit
-
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
07 Mar, 2010
1 commit
-
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
16 Dec, 2009
1 commit
-
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
10 Dec, 2009
1 commit
-
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
23 Sep, 2009
2 commits
-
Many gpio chips allow to generate interrupts when the value of a pin
changes. This patch gives usermode application the opportunity to make
use of this feature by calling poll(2) on the /sys/class/gpio/gpioN/value
sysfs file. The edge to trigger can be set in the edge file in the same
directory. Possible values are "none", "rising", "falling", and "both".Using level triggers is not possible with current sysfs since nothing
changes the GPIO value (and the IRQ keeps triggering). Edge triggering
will "just work". Note that if there was an event between read() and
poll(), the poll() returns immediately.Also note that this version only supports true GPIO interrupts. Some
later patch might be able to synthesize this behavior by timer-driven
polling; some systems seem to need that.[dbrownell@users.sourceforge.net: align ids to 16 bit ids; whitespace]
Signed-off-by: Daniel Glöckner
Signed-off-by: David Brownell
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds -
Commit 926b663ce8215ba448960e1ff6e58b67a2c3b99b (gpiolib: allow GPIOs to
be named) already provides naming on the chip level. This patch provides
more flexibility by allowing multiple names where ever in sysfs on a per
GPIO basis.Adapted from David Brownell's comments on a similar concept:
http://lkml.org/lkml/2009/4/20/203.[randy.dunlap@oracle.com: fix build for CONFIG_GENERIC_GPIO=n]
Signed-off-by: Jani Nikula
Acked-by: David Brownell
Cc: Daniel Silverstone
Signed-off-by: Randy Dunlap
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds
13 Jun, 2009
1 commit
-
Fix various typos in documentation txts.
Signed-off-by: Matt LaPlante
Signed-off-by: Jiri Kosina
03 Apr, 2009
1 commit
-
We want to phase out the GPIO "autorequest" mechanism in gpiolib and
require all callers to use gpio_request().- Update feature-removal-schedule
- Update the documentation now
- Convert the relevant pr_warning() in gpiolib to a WARN()
so folk using this mechanism get a noisy stack dumpSome drivers and board init code will probably need to change.
Implementations not using gpiolib will still be fine; they are already
required to implement gpio_{request,free}() stubs.Signed-off-by: David Brownell
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds
17 Oct, 2008
2 commits
-
Add a new internal mechanism to gpiolib to support low power
operations by letting gpio_chip instances see when their GPIOs
are in use. When no GPIOs are active, chips may be able to
enter lower powered runtime states by disabling clocks and/or
power domains.Signed-off-by: David Brownell
Cc: "Magnus Damm"
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds -
Add a new gpiolib mechanism: gpio_chip instances can provide mappings
between their (input) GPIOs and any associated IRQs. This makes it easier
for platforms to support IRQs that are provided by board-specific external
chips instead of as part of their core (such as SOC-integrated GPIOs).Also update the irq_to_gpio() description, saying to avoid it because it's
not always supported.Signed-off-by: David Brownell
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds
26 Jul, 2008
2 commits
-
This patch adds functionality to the gpio-lib subsystem to make it
possible to enable the gpio-lib code even if the architecture code didn't
request to get it built in.The archtitecture code does still need to implement the gpiolib accessor
functions in its asm/gpio.h file. This patch adds the implementations for
x86 and PPC.With these changes it is possible to run generic GPIO expansion cards on
every architecture that implements the trivial wrapper functions. Support
for more architectures can easily be added.Signed-off-by: Michael Buesch
Cc: Benjamin Herrenschmidt
Cc: Stephen Rothwell
Cc: David Brownell
Cc: Russell King
Cc: Haavard Skinnemoen
Cc: Jesper Nilsson
Cc: Ralf Baechle
Cc: Paul Mackerras
Cc: Benjamin Herrenschmidt
Cc: Ingo Molnar
Cc: Thomas Gleixner
Cc: Jean Delvare
Cc: Samuel Ortiz
Cc: Kumar Gala
Cc: Sam Ravnborg
Cc: Adrian Bunk
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds -
This adds a simple sysfs interface for GPIOs.
/sys/class/gpio
/export ... asks the kernel to export a GPIO to userspace
/unexport ... to return a GPIO to the kernel
/gpioN ... for each exported GPIO #N
/value ... always readable, writes fail for input GPIOs
/direction ... r/w as: in, out (default low); write high, low
/gpiochipN ... for each gpiochip; #N is its first GPIO
/base ... (r/o) same as N
/label ... (r/o) descriptive, not necessarily unique
/ngpio ... (r/o) number of GPIOs; numbered N .. N+(ngpio - 1)GPIOs claimed by kernel code may be exported by its owner using a new
gpio_export() call, which should be most useful for driver debugging.
Such exports may optionally be done without a "direction" attribute.Userspace may ask to take over a GPIO by writing to a sysfs control file,
helping to cope with incomplete board support or other "one-off"
requirements that don't merit full kernel support:echo 23 > /sys/class/gpio/export
... will gpio_request(23, "sysfs") and gpio_export(23);
use /sys/class/gpio/gpio-23/direction to (re)configure it,
when that GPIO can be used as both input and output.
echo 23 > /sys/class/gpio/unexport
... will gpio_free(23), when it was exported as aboveThe extra D-space footprint is a few hundred bytes, except for the sysfs
resources associated with each exported GPIO. The additional I-space
footprint is about two thirds of the current size of gpiolib (!). Since
no /dev node creation is involved, no "udev" support is needed.Related changes:
* This adds a device pointer to "struct gpio_chip". When GPIO
providers initialize that, sysfs gpio class devices become children of
that device instead of being "virtual" devices.* The (few) gpio_chip providers which have such a device node have
been updated.* Some gpio_chip drivers also needed to update their module "owner"
field ... for which missing kerneldoc was added.* Some gpio_chips don't support input GPIOs. Those GPIOs are now
flagged appropriately when the chip is registered.Based on previous patches, and discussion both on and off LKML.
A Documentation/ABI/testing/sysfs-gpio update is ready to submit once this
merges to mainline.[akpm@linux-foundation.org: a few maintenance build fixes]
Signed-off-by: David Brownell
Cc: Guennadi Liakhovetski
Cc: Greg KH
Cc: Kay Sievers
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds
28 Apr, 2008
1 commit
-
Introduce a gpio_is_valid() predicate; use it in gpiolib.
Signed-off-by: Guennadi Liakhovetski
[ use inline function; follow the gpio_* naming convention;
work without gpiolib; all programming interfaces need docs ]
Signed-off-by: David Brownell
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds
05 Mar, 2008
1 commit
-
Add a defining fail/warn stubs for GPIO calls on platforms that
don't support the GPIO programming interface. That includes the arch-specific
implementation glue otherwise.This facilitates a new model for GPIO usage: drivers that can use GPIOs if
they're available, but don't require them. One example of such a driver is
NAND driver for various FreeScale chips. On platforms update with GPIO
support, they can be used instead of a worst-case delay to verify that the
BUSY signal is off.(Also includes a couple minor unrelated doc updates.)
Signed-off-by: David Brownell
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds
06 Feb, 2008
1 commit
-
Update Documentation/gpio.txt, primarily to include the new "gpiolib"
infrastructure.Signed-off-by: David Brownell
Cc: Jean Delvare
Cc: Eric Miao
Cc: Sam Ravnborg
Cc: Haavard Skinnemoen
Cc: Philipp Zabel
Cc: Russell King
Cc: Ben Gardner
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds
25 Jul, 2007
1 commit
-
Fix doc bug noted by Uwe Kleine-König: gpio_set_direction() is long
gone, replaced by gpio_direction_input() and gpio_direction_output().Signed-off-by: David Brownell
Cc:
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds
20 Jul, 2007
1 commit
-
Clarify that drivers using the GPIO operations don't need to issue io
barrier instructions themselves. Previously this wasn't clear, and at
least one platform assumed otherwise (and would thus break various
otherwise-portable drivers which don't issue barriers).Signed-off-by: David Brownell
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds
17 May, 2007
1 commit
-
Loosen gpio_{request,free}() and gpio_direction_{in,out}put() call context
restrictions slightly, so a common idiom is no longer an error: board init
code setting up spinlock-safe GPIOs before tasking is enabled.The issue was caught by some paranoid code with might_sleep() checks. The
legacy platform-specific GPIO interfaces stick to spinlock-safe GPIOs, so this
change reflects current implementations and won't break anything.Signed-off-by: David Brownell
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds
11 May, 2007
1 commit
-
Documentation/gpio.txt should mention the Kconfig GENERIC_GPIO flag, for
platforms to declare when relevant. This should help minimize goofs like
omitting it, or not depending on it when needed.Signed-off-by: David Brownell
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds
13 Apr, 2007
1 commit
-
Update the GPIO docs to describe the idiom whereby open drain signals are
emulated by toggling the GPIO direction.Signed-off-by: David Brownell
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds
17 Mar, 2007
1 commit
-
It's been pointed out that output GPIOs should have an initial value, to
avoid signal glitching ... among other things, it can be some time before
a driver is ready. This patch corrects that oversight, fixing- documentation
- platforms supporting the GPIO interface
- users of that call (just one for now, others are pending)There's only one user of this call for now since most platforms are still
using non-generic GPIO setup code, which in most cases already couples the
initial value with its "set output mode" request.Note that most platforms are clear about the hardware letting the output
value be set before the pin direction is changed, but the s3c241x docs are
vague on that topic ... so those chips might not avoid the glitches.Signed-off-by: David Brownell
Acked-by: Andrew Victor
Acked-by: Milan Svoboda
Acked-by: Haavard Skinnemoen
Cc: Russell King
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds
17 Feb, 2007
1 commit
-
Small updates to the GPIO documentation, addressing feedback and
fixing a few spelling errors.Signed-off-by: David Brownell
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds
13 Feb, 2007
1 commit
-
This defines a simple and minimalist programming interface for GPIO APIs:
- Documentation/gpio.txt ... describes things (read it)
- include/asm-arm/gpio.h ... defines the ARM hook, which just punts
to for any implementation- include/asm-generic/gpio.h ... implement "can sleep" variants as calling
the normal ones, for systems that don't handle i2c expanders.The immediate need for such a cross-architecture API convention is to support
drivers that work the same on AT91 ARM and AVR32 AP7000 chips, which embed many
of the same controllers but have different CPUs. However, several other users
have been reported, including a driver for a hardware watchdog chip and some
handhelds.org multi-CPU button drivers.Signed-off-by: David Brownell
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds