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* gpio: doc updatesDavid Brownell2010-09-091-1/+13
| | | | | | | | | | | | | | 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 <dbrownell@users.sourceforge.net> Cc: Eric Miao" <eric.y.miao@gmail.com> Cc: "Ryan Mallon" <ryan@bluewatersys.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* of/gpio: stop using device_node data pointer to find gpio_chipGrant Likely2010-07-051-0/+3
| | | | | | | | | | | | | | | | | | | | | | | | | | Currently the kernel uses the struct device_node.data pointer to resolve a struct gpio_chip pointer from a device tree node. However, the .data member doesn't provide any type checking and there aren't any rules enforced on what it should be used for. There's no guarantee that the data stored in it actually points to an gpio_chip pointer. Instead of relying on the .data pointer, this patch modifies the code to add a lookup function which scans through the registered gpio_chips and returns the gpio_chip that has a pointer to the specified device_node. Signed-off-by: Grant Likely <grant.likely@secretlab.ca> CC: Andrew Morton <akpm@linux-foundation.org> CC: Anton Vorontsov <avorontsov@ru.mvista.com> CC: Grant Likely <grant.likely@secretlab.ca> CC: David Brownell <dbrownell@users.sourceforge.net> CC: Bill Gatliff <bgat@billgatliff.com> CC: Dmitry Eremin-Solenikov <dbaryshkov@gmail.com> CC: Benjamin Herrenschmidt <benh@kernel.crashing.org> CC: Jean Delvare <khali@linux-fr.org> CC: linux-kernel@vger.kernel.org CC: devicetree-discuss@lists.ozlabs.org
* of/gpio: Kill of_gpio_chip and add members directly to gpio_chipAnton Vorontsov2010-07-051-0/+12
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | The OF gpio infrastructure is great for describing GPIO connections within the device tree. However, using a GPIO binding still requires changes to the gpio controller just to add an of_gpio structure. In most cases, the gpio controller doesn't actually need any special support and the simple OF gpio mapping function is more than sufficient. Additional, the current scheme of using of_gpio_chip requires a convoluted scheme to maintain 1:1 mappings between of_gpio_chip and gpio_chip instances. If the struct of_gpio_chip data members were moved into struct gpio_chip, then it would simplify the processing of OF gpio bindings, and it would make it trivial to use device tree OF connections on existing gpiolib controller drivers. This patch eliminates the of_gpio_chip structure and moves the relevant fields into struct gpio_chip (conditional on CONFIG_OF_GPIO). This move simplifies the existing code and prepares for adding automatic device tree support to existing drivers. Signed-off-by: Grant Likely <grant.likely@secretlab.ca> Cc: Andrew Morton <akpm@linux-foundation.org> Cc: Anton Vorontsov <avorontsov@ru.mvista.com> Cc: Grant Likely <grant.likely@secretlab.ca> Cc: David Brownell <dbrownell@users.sourceforge.net> Cc: Bill Gatliff <bgat@billgatliff.com> Cc: Dmitry Eremin-Solenikov <dbaryshkov@gmail.com> Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org> Cc: Jean Delvare <khali@linux-fr.org>
* gpiolib: introduce set_debounce methodFelipe Balbi2010-05-271-0/+5
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | 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: document that names can contain printk format specifiersUwe Kleine-König2010-05-271-1/+3
| | | | | | | Signed-off-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.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>
* gpiolib: make names array and its values constUwe Kleine-König2010-05-271-1/+1
| | | | | | | | | | | | 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: introduce gpio_request_one() and friendsEric Miao2010-03-061-0/+26
| | | | | | | | | | | | | | 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>
* gpiolib: add support for changing value polarity in sysfsJani Nikula2009-12-161-0/+6
| | | | | | | | | | | | | 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>
* asm-generic/gpio.h: add some forward decls of the device structMike Frysinger2009-12-101-0/+3
| | | | | | | | | | | | | | | | | 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>
* asm-generic/gpio.h: pull in linux/kernel.h for might_sleep()Mike Frysinger2009-10-011-0/+1
| | | | | | | | | | 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>
* gpiolib: allow exported GPIO nodes to be named using sysfs linksJani Nikula2009-09-231-0/+8
| | | | | | | | | | | | | | | | | | 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 <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>
* gpiolib: allow GPIOs to be namedDaniel Silverstone2009-04-021-0/+5
| | | | | | | | | | | 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>
* gpiolib: request/free hooksDavid Brownell2008-10-161-0/+9
| | | | | | | | | | | | | 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>
* gpiolib: gpio_to_irq() hooksDavid Brownell2008-10-161-0/+7
| | | | | | | | | | | | | | 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>
* gpio: make gpiochip label constDmitry Baryshkov2008-10-161-1/+1
| | | | | | | | | | | | 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>
* gpio: fix build on CONFIG_GPIO_SYSFS=nAtsushi Nemoto2008-07-281-0/+1
| | | | | | | | | | If CONFIG_GENERIC_GPIO=y && CONFIG_GPIO_SYSFS=n, gpio_export() in asm-generic/gpio.h refers -ENOSYS and causes build error. Signed-off-by: Atsushi Nemoto <anemo@mba.ocn.ne.jp> 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>
* gpiolib: fix typo in commentMichael Buesch2008-07-261-1/+1
| | | | | | | | | 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>
* gpiolib: allow user-selectionMichael Buesch2008-07-251-1/+1
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | 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>
* gpio: sysfs interfaceDavid Brownell2008-07-251-2/+31
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | 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>
* gpio: build fixesDavid Brownell2008-05-241-1/+5
| | | | | | | | | | | | 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>
* gpiochip_reserve()Anton Vorontsov2008-04-281-0/+1
| | | | | | | | | | | | | | 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>
* gpio: define gpio_is_valid()Guennadi Liakhovetski2008-04-281-0/+12
| | | | | | | | | | | 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>
* gpiolib: better rmmod infrastructureGuennadi Liakhovetski2008-04-281-0/+2
| | | | | | | | | | | | | | | | | 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>
* gpiolib: add gpio provider infrastructureDavid Brownell2008-02-051-0/+98
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | 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>
* [PATCH] GPIO coreDavid Brownell2007-02-121-0/+25
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>