firmware/target/arm/rk27xx/backlight-rk27xx.c

   1 /***************************************************************************
   2  *             __________               __   ___.
   3  *   Open      \______   \ ____   ____ |  | _\_ |__   _______  ___
   4  *   Source     |       _//  _ \_/ ___\|  |/ /| __ \ /  _ \  \/  /
   5  *   Jukebox    |    |   (  <_> )  \___|    < | \_\ (  <_> > <  <
   6  *   Firmware   |____|_  /\____/ \___  >__|_ \|___  /\____/__/\_ \
   7  *                     \/            \/     \/    \/            \/
   8  * $Id$
   9  *
  10  * Copyright (C) 2011 by Marcin Bukat
  11  *
  12  * This program is free software; you can redistribute it and/or
  13  * modify it under the terms of the GNU General Public License
  14  * as published by the Free Software Foundation; either version 2
  15  * of the License, or (at your option) any later version.
  16  *
  17  * This software is distributed on an "AS IS" basis, WITHOUT WARRANTY OF ANY
  18  * KIND, either express or implied.
  19  *
  20  ****************************************************************************/
  21 #include <stdbool.h>
  22
  23 #include "config.h"
  24 #include "backlight.h"
  25 #include "backlight-target.h"
  26 #include "system.h"
  27
  28 bool _backlight_init(void)
  29 {
  30     /* configure PD4 as output */
  31     GPIO_PDCON |= (1<<4);
  32
  33     /* set PD4 low (backlight off) */
  34     GPIO_PDDR &= ~(1<<4);
  35
  36     /* IOMUXB - set PWM0 pin as GPIO */
  37     SCU_IOMUXB_CON &= ~(1 << 11); /* type<<11<<channel */
  38
  39     /* setup pwm */
  40     PWMT0_CTRL = (0<<9) | (1<<7);
  41
  42     /* set pwm frequency ~10kHz */
  43     /* (apb_freq/pwm_freq)/pwm_div = (50 000 000/10 000)/2 */
  44     PWMT0_LRC = 2500;
  45     PWMT0_HRC = 1;
  46
  47     PWMT0_CNTR = 0x00;
  48     PWMT0_CTRL = (0<<9) | (1<<3) | (1<<0);
  49
  50     return true;
  51 }
  52
  53 void _backlight_on(void)
  54 {
  55     /* enable PWM clock */
  56     SCU_CLKCFG &= ~(1<<29);
  57
  58     /* set output pin as PWM pin */
  59     SCU_IOMUXB_CON |= (1<<11); /* type<<11<<channel */
  60
  61     /* 100% duty cycle. Other settings doesn't work for
  62      * unknown reason
  63      */
  64     PWMT0_HRC = PWMT0_LRC;
  65
  66     /* pwm enable */
  67     PWMT0_CTRL |= (1<<3) | (1<<0);
  68 }
  69
  70 void _backlight_off(void)
  71 {
  72     /* setup PWM0 pin as GPIO which is pulled low */
  73     SCU_IOMUXB_CON &= ~(1<<11);
  74
  75     /* stop pwm timer */
  76     PWMT0_CTRL &= ~(1<<3) | (1<<0);
  77
  78     /* disable PWM clock */
  79     SCU_CLKCFG |= (1<<29);
  80 }
  81
  82 void _backlight_set_brightness(int brightness)
  83 {
  84     (void)brightness;
  85     /* doesn't work for unknown reason */
  86 }