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fbdev: LCD backlight driver using Atmel PWM driver

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This patch adds a platform driver using the ATMEL PWM driver to control a
backlight which requires a PWM signal and optional GPIO signal for discrete
on/off signal.  It has been tested on Favr-32 board from EarthLCD.

The driver is configurable by supplying a struct with the platform data.  See
the include/linux/atmel-pwm-bl.h for details.

The board code for Favr-32 will be submitted to the AVR32 kernel list.

Signed-off-by: Hans-Christian Egtvedt <hans-christian.egtvedt@atmel.com>
Cc: Krzysztof Helt <krzysztof.h1@poczta.fm>
Cc: Haavard Skinnemoen <hskinnemoen@atmel.com>
Cc: Richard Purdie <rpurdie@rpsys.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Hans-Christian Egtvedt 2008-07-23 21:31:48 -07:00 • committed by Linus Torvalds
parent 2d04a4a72d
commit 3e074058d7
4 changed files with 300 additions and 0 deletions
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43
include/linux/atmel-pwm-bl.h Normal file
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/*
* Copyright (C) 2007 Atmel Corporation
*
* Driver for the AT32AP700X PS/2 controller (PSIF).
*
* This program is free software; you can redistribute it and/or modify it
* under the terms of the GNU General Public License version 2 as published
* by the Free Software Foundation.
*/
#ifndef __INCLUDE_ATMEL_PWM_BL_H
#define __INCLUDE_ATMEL_PWM_BL_H
/**
* struct atmel_pwm_bl_platform_data
* @pwm_channel: which PWM channel in the PWM module to use.
* @pwm_frequency: PWM frequency to generate, the driver will try to be as
* close as the prescaler allows.
* @pwm_compare_max: value to use in the PWM channel compare register.
* @pwm_duty_max: maximum duty cycle value, must be less than or equal to
* pwm_compare_max.
* @pwm_duty_min: minimum duty cycle value, must be less than pwm_duty_max.
* @pwm_active_low: set to one if the low part of the PWM signal increases the
* brightness of the backlight.
* @gpio_on: GPIO line to control the backlight on/off, set to -1 if not used.
* @on_active_low: set to one if the on/off signal is on when GPIO is low.
*
* This struct must be added to the platform device in the board code. It is
* used by the atmel-pwm-bl driver to setup the GPIO to control on/off and the
* PWM device.
*/
struct atmel_pwm_bl_platform_data {
unsigned int pwm_channel;
unsigned int pwm_frequency;
unsigned int pwm_compare_max;
unsigned int pwm_duty_max;
unsigned int pwm_duty_min;
unsigned int pwm_active_low;
int gpio_on;
unsigned int on_active_low;
};
#endif /* __INCLUDE_ATMEL_PWM_BL_H */