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authorDavid Brownell <david-b@pacbell.net>2008-02-08 07:21:22 -0500
committerLinus Torvalds <torvalds@woody.linux-foundation.org>2008-02-08 12:22:38 -0500
commitde5c9edee7a3cfdc6dd1a31c4794dc41ef3c70f9 (patch)
tree2cc474aa124cd9efb8aa5b96072dd3fd2325148b /drivers/leds/Kconfig
parent9a1e8eb1f0b76b5e72a2343ad881c81b08dd6410 (diff)
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/Kconfig7
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
18 18
19comment "LED drivers" 19comment "LED drivers"
20 20
21config LEDS_ATMEL_PWM
22 tristate "LED Support using Atmel PWM outputs"
23 depends on LEDS_CLASS && ATMEL_PWM
24 help
25 This option enables support for LEDs driven using outputs
26 of the dedicated PWM controller found on newer Atmel SOCs.
27
21config LEDS_CORGI 28config LEDS_CORGI
22 tristate "LED Support for the Sharp SL-C7x0 series" 29 tristate "LED Support for the Sharp SL-C7x0 series"
23 depends on LEDS_CLASS && PXA_SHARP_C7xx 30 depends on LEDS_CLASS && PXA_SHARP_C7xx