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| author | David Brownell <david-b@pacbell.net> | 2008-02-08 04:21:22 -0800 |
|---|---|---|
| committer | Linus Torvalds <torvalds@woody.linux-foundation.org> | 2008-02-08 09:22:38 -0800 |
| commit | de5c9edee7a3cfdc6dd1a31c4794dc41ef3c70f9 (patch) | |
| tree | 2cc474aa124cd9efb8aa5b96072dd3fd2325148b /drivers/leds/Kconfig | |
| parent | 9a1e8eb1f0b76b5e72a2343ad881c81b08dd6410 (diff) | |
| download | blackbird-op-linux-de5c9edee7a3cfdc6dd1a31c4794dc41ef3c70f9.tar.gz blackbird-op-linux-de5c9edee7a3cfdc6dd1a31c4794dc41ef3c70f9.zip | |
PWM LED driver
This is a LED driver using the PWM on newer SOCs from Atmel; brightness is
controlled by changing the PWM duty cycle. So for example if you've set up
two leds labeled "pwm0" and "pwm1":
echo 0 > /sys/class/leds/pwm2/brightness # off (0%)
echo 80 > /sys/class/leds/pwm2/brightness
echo 255 > /sys/class/leds/pwm2/brightness # on (100%)
Note that "brightness" here isn't linear; maybe that should change. Going
from 4 to 8 probably doubles perceived brightness, while 244 to 248 is
imperceptible.
This is mostly intended to be a simple example of PWM, although it's
realistic since LCD backlights are often driven with PWM to conserve
battery power (and offer brightness options).
Signed-off-by: David Brownell <dbrownell@users.sourceforge.net>
Signed-off-by: Haavard Skinnemoen <hskinnemoen@atmel.com>
Cc: Richard Purdie <rpurdie@rpsys.net>
Cc: Andrew Victor <linux@maxim.org.za>
Cc: Nicolas Ferre <nicolas.ferre@atmel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'drivers/leds/Kconfig')
| -rw-r--r-- | drivers/leds/Kconfig | 7 |
1 files changed, 7 insertions, 0 deletions
diff --git a/drivers/leds/Kconfig b/drivers/leds/Kconfig index 851a3b01781e..859814f62cb0 100644 --- a/drivers/leds/Kconfig +++ b/drivers/leds/Kconfig @@ -18,6 +18,13 @@ config LEDS_CLASS comment "LED drivers" +config LEDS_ATMEL_PWM + tristate "LED Support using Atmel PWM outputs" + depends on LEDS_CLASS && ATMEL_PWM + help + This option enables support for LEDs driven using outputs + of the dedicated PWM controller found on newer Atmel SOCs. + config LEDS_CORGI tristate "LED Support for the Sharp SL-C7x0 series" depends on LEDS_CLASS && PXA_SHARP_C7xx |
