A few architectures, like OMAP, allow you to set a debouncing time for the
gpio before generating the IRQ. Teach gpiolib about that.
Mark said:
: This would be generally useful for embedded systems, especially where
: the interrupt concerned is a wake source. It allows drivers to avoid
: spurious interrupts from noisy sources so if the hardware supports it
: the driver can avoid having to explicitly wait for the signal to become
: stable and software has to cope with fewer events. We've lived without
: it for quite some time, though.
David said:
: I looked at adding debounce support to the generic GPIO calls (and thus
: gpiolib) some time back, but decided against it. I forget why at this
: time (check list archives) but it wasn't because of lack of utility in
: certain contexts.
:
: One thing to watch out for is just how variable the hardware capabilities
: are. Atmel GPIOs have something like a fixed number of 32K clock cycles
: for debounce, twl4030 had something odd, OMAPs were more like the Atmel
: chips but with a different clock. In some cases debouncing had to be
: ganged, not per-GPIO. And so forth.
Signed-off-by: Felipe Balbi <felipe.balbi@nokia.com>
Cc: Tony Lindgren <tony@atomide.com>
Cc: David Brownell <david-b@pacbell.net>
Reviewed-by: Mark Brown <broonie@opensource.wolfsonmicro.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
gpiolib doesn't need to modify the names and I assume most initializers
use string constants that shouldn't be modified anyhow.
[akpm@linux-foundation.org: fix drivers/gpio/cs5535-gpio.c]
Signed-off-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
Cc: Kevin Wells <kevin.wells@nxp.com>
Cc: David Brownell <david-b@pacbell.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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 <eric.y.miao@gmail.com>
Cc: David Brownell <dbrownell@users.sourceforge.net>
Cc: Ben Nizette <bn@niasdigital.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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 <ext-jani.1.nikula@nokia.com>
Cc: David Brownell <david-b@pacbell.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
After the recent commit a4177ee7f, attempting to include asm-generic/gpio.h
in otherwise "slim" code results in ugly warnings like so:
CC arch/blackfin/kernel/bfin_gpio.o
In file included from arch/blackfin/include/asm/gpio.h:278,
from arch/blackfin/kernel/bfin_gpio.c:15:
include/asm-generic/gpio.h:193: warning:
‘struct device’ declared inside parameter list
its scope is only this definition or declaration, which is probably not what you want
So add simple C forward decls of the struct device to avoid these.
Signed-off-by: Mike Frysinger <vapier@gentoo.org>
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
The asm-generic/gpio.h header uses the might_sleep() macro but doesn't
include the header for it, so any source code that might include
linux/gpio.h before linux/kernel.h can easily lead to a build failure.
Signed-off-by: Mike Frysinger <vapier@gentoo.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Commit 926b663ce8 (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 <ext-jani.1.nikula@nokia.com>
Acked-by: David Brownell <david-b@pacbell.net>
Cc: Daniel Silverstone <dsilvers@simtec.co.uk>
Signed-off-by: Randy Dunlap <randy.dunlap@oracle.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Allow GPIOs in GPIOLIB chips to be named. This name is then used when the
GPIO is exported to sysfs, although it could be used elsewhere if deemed
useful.
Signed-off-by: Daniel Silverstone <dsilvers@simtec.co.uk>
Cc: David Brownell <david-b@pacbell.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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 <dbrownell@users.sourceforge.net>
Cc: "Magnus Damm" <magnus.damm@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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 <dbrownell@users.sourceforge.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Mark gpiochip label as a const char pointer. Fixes things like
arch/arm/common/scoop.c: In function `scoop_probe':
arch/arm/common/scoop.c:250: warning: assignment discards qualifiers from pointer target type
Signed-off-by: Dmitry Baryshkov <dbaryshkov@gmail.com>
Acked-by: David Brownell <dbrownell@users.sourceforge.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This fixes an off-by-one error in a comment.
Signed-off-by: Michael Buesch <mb@bu3sch.de>
Cc: David Brownell <david-b@pacbell.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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 <mb@bu3sch.de>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Stephen Rothwell <sfr@canb.auug.org.au>
Cc: David Brownell <david-b@pacbell.net>
Cc: Russell King <rmk@arm.linux.org.uk>
Cc: Haavard Skinnemoen <hskinnemoen@atmel.com>
Cc: Jesper Nilsson <jesper.nilsson@axis.com>
Cc: Ralf Baechle <ralf@linux-mips.org>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Jean Delvare <khali@linux-fr.org>
Cc: Samuel Ortiz <sameo@openedhand.com>
Cc: Kumar Gala <galak@gate.crashing.org>
Cc: Sam Ravnborg <sam@ravnborg.org>
Cc: Adrian Bunk <bunk@stusta.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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 above
The 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 <dbrownell@users.sourceforge.net>
Cc: Guennadi Liakhovetski <g.liakhovetski@pengutronix.de>
Cc: Greg KH <greg@kroah.com>
Cc: Kay Sievers <kay.sievers@vrfy.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This fixes various gpio-related build errors (mostly potential)
reported in part by Russell King and Uwe Kleine-König.
Signed-off-by: David Brownell <dbrownell@users.sourceforge.net>
Cc: Uwe Kleine-König <Uwe.Kleine-Koenig@digi.com>
Cc: Russell King <rmk@arm.linux.org.uk>
Cc: Arnaud Patard <arnaud.patard@rtp-net.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Add a new function gpiochip_reserve() to reserve ranges of gpios that platform
code has pre-allocated. That is, this marks gpio numbers which will be
claimed by drivers that haven't yet been loaded, and thus are not available
for dynamic gpio number allocation.
[akpm@linux-foundation.org: remove unneeded __must_check]
[david-b@pacbell.net: don't export gpiochip_reserve (section fix)]
Signed-off-by: Anton Vorontsov <avorontsov@ru.mvista.com>
Signed-off-by: David Brownell <dbrownell@users.sourceforge.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Introduce a gpio_is_valid() predicate; use it in gpiolib.
Signed-off-by: Guennadi Liakhovetski <g.liakhovetski@pengutronix.de>
[ use inline function; follow the gpio_* naming convention;
work without gpiolib; all programming interfaces need docs ]
Signed-off-by: David Brownell <dbrownell@users.sourceforge.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
As long as one or more GPIOs on a gpio chip are used its driver should not be
unloaded. The existing mechanism (gpiochip_remove failure) doesn't address
that, since rmmod can no longer be made to fail by having the cleanup code
report errors. Module usecounts are the solution.
Assuming standard "initialize struct to zero" policies, this change won't
affect SOC platform drivers. However, drivers for external chips (on I2C and
SPI busses) should be updated if they can be built as modules.
Signed-off-by: Guennadi Liakhovetski <g.liakhovetski@pengutronix.de>
[ gpio_ensure_requested() needs to update module usecounts too ]
Signed-off-by: David Brownell <dbrownell@users.sourceforge.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Provide new implementation infrastructure that platforms may choose to use
when implementing the GPIO programming interface. Platforms can update their
GPIO support to use this. In many cases the incremental cost to access a
non-inlined GPIO should be less than a dozen instructions, with the memory
cost being about a page (total) of extra data and code. The upside is:
* Providing two features which were "want to have (but OK to defer)" when
GPIO interfaces were first discussed in November 2006:
- A "struct gpio_chip" to plug in GPIOs that aren't directly supported
by SOC platforms, but come from FPGAs or other multifunction devices
using conventional device registers (like UCB-1x00 or SM501 GPIOs,
and southbridges in PCs with more open specs than usual).
- Full support for message-based GPIO expanders, where registers are
accessed through sleeping I/O calls. Previous support for these
"cansleep" calls was just stubs. (One example: the widely used
pcf8574 I2C chips, with 8 GPIOs each.)
* Including a non-stub implementation of the gpio_{request,free}() calls,
making those calls much more useful. The diagnostic labels are also
recorded given DEBUG_FS, so /sys/kernel/debug/gpio can show a snapshot
of all GPIOs known to this infrastructure.
The driver programming interfaces introduced in 2.6.21 do not change at all;
this infrastructure is entirely below those covers.
Signed-off-by: David Brownell <dbrownell@users.sourceforge.net>
Cc: Sam Ravnborg <sam@ravnborg.org>
Cc: Jean Delvare <khali@linux-fr.org>
Cc: Eric Miao <eric.miao@marvell.com>
Cc: Haavard Skinnemoen <hskinnemoen@atmel.com>
Cc: Philipp Zabel <philipp.zabel@gmail.com>
Cc: Russell King <rmk@arm.linux.org.uk>
Cc: Ben Gardner <bgardner@wabtec.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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 <asm/arch/gpio.h> 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 <dbrownell@users.sourceforge.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Felipe Balbi