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/Makefile | 1 + 1 file changed, 1 insertion(+) (limited to 'drivers/leds/Makefile') diff --git a/drivers/leds/Makefile b/drivers/leds/Makefile index bc6afc8dcb27..84ced3b1a13d 100644 --- a/drivers/leds/Makefile +++ b/drivers/leds/Makefile @@ -5,6 +5,7 @@ obj-$(CONFIG_LEDS_CLASS) += led-class.o obj-$(CONFIG_LEDS_TRIGGERS) += led-triggers.o # LED Platform Drivers +obj-$(CONFIG_LEDS_ATMEL_PWM) += leds-atmel-pwm.o obj-$(CONFIG_LEDS_CORGI) += leds-corgi.o obj-$(CONFIG_LEDS_LOCOMO) += leds-locomo.o obj-$(CONFIG_LEDS_SPITZ) += leds-spitz.o -- cgit v1.2.3