LED

Welcome to the LED  webpage.

Introduction
This webpage describes the LED software development effort, mainly its current status and features planned in the road map.

On OMAP4 Debug, Tri-color and Charging LEDs are supported. Debug and Tri-color are GPIO based LEDs, while charging LED is controlled by TWL6030 PWM (Pulse Width Modulator). Charging LED allows for controlling brightness, while other LEDs can just we switched ON/OFF.

List of Features Supported

 * On OMAP4
 * ON/OFF for Debug/Tri-color LED
 * Brightness control for Charging LED

Design



 * SYS FS Interface
 * This is a generic Linux framework for device drivers and is available through /sys on the filesystem. It exports driver specific interfaces to user space.
 * LED Class Framework
 * This is a generic driver for controlling all LEDs. This exposes SYS FS interfaces for user space and also interfaces with GPIO or PWM driver for controlling the LED.


 * GPIO LED Driver
 * This is a generic GPIO LED driver for controlling GPIO LEDs. This driver extracts information from platform data for controlling LED. Platform data needs to specify which GPIO pin controls this particular LED, whether its active low etc


 * PWM Led Driver
 * This is a generic PWM based driver for LED control. APIs are defined for accessing PWM (Pulse Width Modulator). These APIs are implemented by twl6030-pwm, since accessing PWM is platform dependent

Feature Status Summary
Here is the summary of completed, ongoing and planned features in the LED driver.

 LED Driver

Defect Status Summary
Here is the summary of completed, ongoing and planned defect fixes in the LED driver.

 LED Driver

FAQ
TBD

SR:LED.0000
Tri-color, Debug, PWM LEDs shall be supported through the linux sysfs LED class: Supported

Defect Status Details
None reported so far

Future Development Plan
None at present

Information on Testing Procedures

 * GPIO LED (omap4:green:debug* and omap4:*: user)
 * cd /sys/class/leds/omap4:green:debug0
 * echo 1 > brightness
 * check LED is ON
 * echo 0 > brightness
 * check LED is OFF
 * cd /sys/class/leds/omap4:red:user
 * echo 1 > brightness
 * check RED LED is ON
 * echo 0 > brightness
 * check RED LED is OFF
 * PWM Charging LED
 * This is available on ES2.0 and later processor boards
 * cd /sys/class/leds/omap4:green:chrg
 * echo 10 > brightness
 * echo 100 > brightness
 * echo 255 > brightness
 * echo 0 > brightness
 * Brightness should increase with value and should go off with 0 value

Submit Your Ideas Here
Please list them as separate subsections (use ===title===). Please include your name, email ID and date for easy processing.

Owner
Hemanth V 

Contributors
Hemanth V 

Patches Merged in kernel.org
None

Recent Submissions to Open Source

 * https://patchwork.kernel.org/patch/108841/
 * https://patchwork.kernel.org/patch/110827/

Current Status of Patches in Omapzoom Tree
None