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 static int brightness = DEFAULT_BRIGHTNESS_SETTING;
  29 static const unsigned short log_brightness[] = {
  30     0x2710, 0x27ac, 0x2849, 0x2983, 0x2abd, 0x2c93, 0x2e6a, 0x30dd,
  31     0x3351, 0x3661, 0x3971, 0x3d1f, 0x40cc, 0x4516, 0x4960, 0x4e47,
  32     0x532e, 0x58b1, 0x5e35, 0x6456, 0x6a76, 0x7134, 0x77f1, 0x7f4c,
  33     0x86a6, 0x8e9d, 0x9695, 0x9f29, 0xa7bd, 0xb0ee, 0xba1f, 0xc350
  34 };
  35
  36 bool _backlight_init(void)
  37 {
  38     /* configure PD4 as output */
  39     GPIO_PDCON |= (1<<4);
  40
  41     /* set PD4 low (backlight off) */
  42     GPIO_PDDR &= ~(1<<4);
  43
  44     /* IOMUXB - set PWM0 pin as GPIO */
  45     SCU_IOMUXB_CON &= ~(1 << 11); /* type<<11<<channel */
  46
  47     /* DIV/2, PWM reset */
  48     PWMT0_CTRL = (0<<9) | (1<<7);
  49
  50     /* set pwm frequency to 500Hz - my lcd panel can't cope more reliably */
  51     /* (apb_freq/pwm_freq)/pwm_div = (50 000 000/500)/2 */
  52     PWMT0_LRC = 50000;
  53     PWMT0_HRC = log_brightness[brightness];
  54
  55     /* reset counter */
  56     PWMT0_CNTR = 0x00;
  57
  58     /* DIV/2, PWM output enable, PWM timer enable */
  59     PWMT0_CTRL = (0<<9) | (1<<3) | (1<<0);
  60
  61     return true;
  62 }
  63
  64 void _backlight_on(void)
  65 {
  66     /* enable PWM clock */
  67     SCU_CLKCFG &= ~(1<<29);
  68
  69     /* set output pin as PWM pin */
  70     SCU_IOMUXB_CON |= (1<<11); /* type<<11<<channel */
  71
  72     /* pwm enable */
  73     PWMT0_CTRL |= (1<<3) | (1<<0);
  74 }
  75
  76 void _backlight_off(void)
  77 {
  78     /* setup PWM0 pin as GPIO which is pulled low */
  79     SCU_IOMUXB_CON &= ~(1<<11);
  80
  81     /* stop pwm timer */
  82     PWMT0_CTRL &= ~(1<<3) | (1<<0);
  83
  84     /* disable PWM clock */
  85     SCU_CLKCFG |= (1<<29);
  86 }
  87
  88 void _backlight_set_brightness(int val)
  89 {
  90     brightness = val & 0x1f;
  91     PWMT0_HRC = log_brightness[brightness];
  92 }