From de5c9edee7a3cfdc6dd1a31c4794dc41ef3c70f9 Mon Sep 17 00:00:00 2001 From: David Brownell Date: Fri, 8 Feb 2008 04:21:22 -0800 Subject: 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 Signed-off-by: Haavard Skinnemoen Cc: Richard Purdie Cc: Andrew Victor Cc: Nicolas Ferre Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- drivers/leds/Kconfig | 7 +++++++ 1 file changed, 7 insertions(+) (limited to 'drivers/leds/Kconfig') diff --git a/drivers/leds/Kconfig b/drivers/leds/Kconfig index 851a3b01781..859814f62cb 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 -- cgit v1.2.3