de5c9edee7
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>
29 lines
1.1 KiB
Makefile
29 lines
1.1 KiB
Makefile
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# LED Core
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obj-$(CONFIG_NEW_LEDS) += led-core.o
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obj-$(CONFIG_LEDS_CLASS) += led-class.o
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obj-$(CONFIG_LEDS_TRIGGERS) += led-triggers.o
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# LED Platform Drivers
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obj-$(CONFIG_LEDS_ATMEL_PWM) += leds-atmel-pwm.o
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obj-$(CONFIG_LEDS_CORGI) += leds-corgi.o
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obj-$(CONFIG_LEDS_LOCOMO) += leds-locomo.o
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obj-$(CONFIG_LEDS_SPITZ) += leds-spitz.o
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obj-$(CONFIG_LEDS_TOSA) += leds-tosa.o
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obj-$(CONFIG_LEDS_S3C24XX) += leds-s3c24xx.o
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obj-$(CONFIG_LEDS_AMS_DELTA) += leds-ams-delta.o
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obj-$(CONFIG_LEDS_NET48XX) += leds-net48xx.o
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obj-$(CONFIG_LEDS_WRAP) += leds-wrap.o
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obj-$(CONFIG_LEDS_H1940) += leds-h1940.o
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obj-$(CONFIG_LEDS_COBALT_QUBE) += leds-cobalt-qube.o
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obj-$(CONFIG_LEDS_COBALT_RAQ) += leds-cobalt-raq.o
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obj-$(CONFIG_LEDS_GPIO) += leds-gpio.o
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obj-$(CONFIG_LEDS_CM_X270) += leds-cm-x270.o
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obj-$(CONFIG_LEDS_CLEVO_MAIL) += leds-clevo-mail.o
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obj-$(CONFIG_LEDS_HP6XX) += leds-hp6xx.o
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# LED Triggers
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obj-$(CONFIG_LEDS_TRIGGER_TIMER) += ledtrig-timer.o
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obj-$(CONFIG_LEDS_TRIGGER_IDE_DISK) += ledtrig-ide-disk.o
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obj-$(CONFIG_LEDS_TRIGGER_HEARTBEAT) += ledtrig-heartbeat.o
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