There already is a "default-on" trigger but there are problems with it.
For one, it's a inefficient way to do it and requires led trigger support
to be compiled in.
But the real reason is that is produces a glitch on the LED. The GPIO is
allocate with the LED *off*, then *later* when the trigger runs it is
turned back on. If the LED was already on via the GPIO's reset default or
action of the firmware, this produces a glitch where the LED goes from on
to off to on. While normally this is fast enough that it wouldn't be
noticeable to a human observer, there are still serious problems.
One is that there may be something else on the GPIO line, like a hardware
alarm or watchdog, that is fast enough to notice the glitch.
Another is that the kernel may panic before the LED is turned back on, thus
hanging with the LED in the wrong state. This is not just speculation, but
actually happened to me with an embedded system that has an LED which
should turn off when the kernel finishes booting, which was left in the
incorrect state due to a bug in the OF LED binding code.
We also let GPIO LEDs get their initial value from whatever the current
state of the GPIO line is. On some systems the LEDs are put into some
state by the firmware or hardware before Linux boots, and it is desired to
have them keep this state which is otherwise unknown to Linux.
This requires that the underlying GPIO driver support reading the value of
output GPIOs. Some drivers support this and some do not.
The platform device binding gains a field in the platform data
"default_state" that controls this. There are three constants defined to
select from on, off, or keeping the current state. The OpenFirmware
binding uses a property named "default-state" that can be set to "on",
"off", or "keep". The default if the property isn't present is off.
Signed-off-by: Trent Piepho <xyzzy@speakeasy.org>
Acked-by: Grant Likely <grant.likely@secretlab.ca>
Acked-by: Wolfram Sang <w.sang@pengutronix.de>
Acked-by: Sean MacLennan <smaclennan@pikatech.com>
Signed-off-by: Richard Purdie <rpurdie@linux.intel.com>
The documentation for the parameters of blink_set() was a bit hard
to find so put some where I'd expected to find it.
Signed-off-by: Mark Brown <broonie@opensource.wolfsonmicro.com>
Signed-off-by: Richard Purdie <rpurdie@linux.intel.com>
Add an option to preserve LED state when suspending/resuming to the LED
gpio driver. Based on a suggestion from Robert Jarzmik.
Tested-by: Robert Jarzmik <robert.jarzmik@free.fr>
Signed-off-by: Richard Purdie <rpurdie@linux.intel.com>
This patch allows drivers to override the default maximum brightness value
of 255. We take care to preserve backwards-compatibility as much as
possible, so that user-space ABI doesn't change for existing drivers.
LED trigger code has also been updated to use the per-LED maximum.
Signed-off-by: Guennadi Liakhovetski <lg@denx.de>
Signed-off-by: Richard Purdie <rpurdie@linux.intel.com>
Add suspend/resume to the core class and remove all the now unneeded
code from various drivers. Originally the class code couldn't support
suspend/resume but since class_device can there is no reason for
each driver doing its own suspend/resume anymore.
There is one place where the struct led_classdev as the function
argument is named differently. Fix it.
Signed-off-by: Wolfram Sang <w.sang@pengutronix.de>
Signed-off-by: Richard Purdie <rpurdie@linux.intel.com>
The default_trigger fields of struct gpio_led and thus struct
led_classdev are pretty much always assigned from a string literal,
which means the string can't be modified. Which is fine, since there is
no reason to modify the string and in fact it never is.
But they should be marked const to prevent such code from being added,
to prevent warnings if -Wwrite-strings is used, when assigned from a
constant string other than a string literal (which produces a warning
under current kernel compiler flags), and for general good coding
practices.
Signed-off-by: Trent Piepho <tpiepho@freescale.com>
Signed-off-by: Richard Purdie <rpurdie@linux.intel.com>
This driver supports the PCA9550, PCA9551, PCA9552, and PCA9553
LED driver chips.
Signed-off-by: Nate Case <ncase@xes-inc.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Richard Purdie <rpurdie@rpsys.net>
LED classdev core doesn't modify memory pointed by the default_trigger,
so mark it as const and we'll able to pass const char *s without getting
compiler warnings.
Signed-off-by: Anton Vorontsov <avorontsov@ru.mvista.com>
Signed-off-by: Richard Purdie <rpurdie@rpsys.net>
Make sure there is no confusion about the contexts brightness_set
can be called under by documenting it.
Signed-off-by: Richard Purdie <rpurdie@rpsys.net>
Some led hardware allows drivers to query the led state, and this patch
adds a hook to let the led class take advantage of that information when
available.
Without this functionality, when access to the led hardware is not
exclusive (i.e. firmware or hardware might change its state behind the
kernel's back), reality goes out of sync with the led class' idea of what
the led is doing, which is annoying at best.
Behaviour for drivers that do not or cannot read the led status is
unchanged.
Signed-off-by: Henrique de Moraes Holschuh <hmh@hmh.eng.br>
Signed-off-by: Richard Purdie <rpurdie@rpsys.net>
Enhance leds-gpio to provide hardware-based led flashing by passing
through the blink_set() call to a optionally set platform-specific
function pointer.
Signed-off-by: Herbert Valerio Riedel <hvr@gnu.org>
Signed-off-by: Richard Purdie <rpurdie@rpsys.net>
After 2.6.24 there was a plan to make the PM core acquire all device
semaphores during a suspend/hibernation to protect itself from
concurrent operations involving device objects. That proved to be
too heavy-handed and we found a better way to achieve the goal, but
before it happened, we had introduced the functions
device_pm_schedule_removal() and destroy_suspended_device() to allow
drivers to "safely" destroy a suspended device and we had adapted some
drivers to use them. Now that these functions are no longer necessary,
it seems reasonable to remove them and modify their users to use the
normal device unregistration instead.
Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl>
Acked-by: Pavel Machek <pavel@ucw.cz>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
Extends the leds subsystem with a blink_set() callback function which can
be optionally implemented by a LED driver. If implemented, the driver can use
the hardware acceleration for blinking a LED.
Signed-off-by: Márton Németh <nm127@freemail.hu>
Signed-off-by: Richard Purdie <rpurdie@rpsys.net>
Make it possible to unregister a led classdev object in a safe way during a
suspend/resume cycle.
Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl>
Cc: Michael Buesch <mb@bu3sch.de>
Cc: Pavel Machek <pavel@ucw.cz>
Cc: "John W. Linville" <linville@tuxdriver.com>
Cc: Alan Stern <stern@rowland.harvard.edu>
Cc: Len Brown <lenb@kernel.org>
Cc: Greg KH <greg@kroah.com>
Cc: Kay Sievers <kay.sievers@vrfy.org>
Cc: Richard Purdie <rpurdie@rpsys.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Convert part of the led trigger core from rw spinlocks to rw
semaphores. We're calling functions which can sleep from invalid
contexts otherwise. Fixes bug #9264.
Signed-off-by: Richard Purdie <rpurdie@rpsys.net>
This patch has added #include <linux/spinlock.h> to include/linux/leds.h
for rwlock_t.
Signed-off-by: Yoichi Yuasa <yoichi_yuasa@tripeaks.co.jp>
Signed-off-by: Richard Purdie <rpurdie@rpsys.net>
* 'for-linus' of git://git.o-hand.com/linux-rpurdie-leds:
leds: Convert from struct class_device to struct device
leds: leds-gpio for ngw100
leds: Add warning printks in error paths
leds: Fix trigger unregister_simple if register_simple fails
leds: Use menuconfig objects II - LED
leds: Teach leds-gpio to handle timer-unsafe GPIOs
leds: Add generic GPIO LED driver
Remove the obviously unnecessary includes of <linux/spinlock.h> under the
include/linux/ directory, and fix the couple errors that are introduced as
a result of that.
Signed-off-by: Robert P. J. Day <rpjday@mindspring.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Convert the LEDs class from struct class_device to struct device
since class_device is scheduled for removal.
Signed-off-by: Richard Purdie <rpurdie@rpsys.net>
Acked-by: Greg Kroah-Hartman <gregkh@suse.de>
This patch adds support for GPIO connected leds via the new GPIO framework.
Information about leds (gpio, polarity, name, default trigger) is passed
to the driver via platform_data.
Signed-off-by: Raphael Assenat <raph@8d.com>
Signed-off-by: Richard Purdie <rpurdie@rpsys.net>
Make it possible to include linux/leds.h without first including list.h and
spinlock.h.
Signed-off-by: Johannes Berg <johannes@sipsolutions.net>
Acked-by: Richard Purdie <rpurdie@rpsys.net>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
Lay out the structure definitions in include/linux/leds.h to be aligned as
much as possible. Also minor updates to the comments to make them more
concise.
Signed-off-by: Ben Dooks <ben-linux@fluff.org>
Acked-by: Richard Purdie <rpurdie@rpsys.net>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
Add an LED trigger for IDE disk activity to the ide-disk driver.
Signed-off-by: Richard Purdie <rpurdie@rpsys.net>
Acked-by: Bartlomiej Zolnierkiewicz <B.Zolnierkiewicz@elka.pw.edu.pl>
Cc: Alan Cox <alan@lxorguk.ukuu.org.uk>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
Add support for LED triggers to the LED subsystem. "Triggers" are events
which change the state of an LED. Two kinds of trigger are available, simple
ones which can be added to exising code with minimum disruption and complex
ones for implementing new or more complex functionality.
Signed-off-by: Richard Purdie <rpurdie@rpsys.net>
Cc: Russell King <rmk@arm.linux.org.uk>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
Add the foundations of a new LEDs subsystem. This patch adds a class which
presents LED devices within sysfs and allows their brightness to be
controlled.
Signed-off-by: Richard Purdie <rpurdie@rpsys.net>
Cc: Russell King <rmk@arm.linux.org.uk>
Cc: Greg KH <greg@kroah.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
Richard Purdie