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

   1 /***************************************************************************
   2  *             __________               __   ___.
   3  *   Open      \______   \ ____   ____ |  | _\_ |__   _______  ___
   4  *   Source     |       _//  _ \_/ ___\|  |/ /| __ \ /  _ \  \/  /
   5  *   Jukebox    |    |   (  <_> )  \___|    < | \_\ (  <_> > <  <
   6  *   Firmware   |____|_  /\____/ \___  >__|_ \|___  /\____/__/\_ \
   7  *                     \/            \/     \/    \/            \/
   8  * $Id$
   9  *
  10  * Copyright (C) 2011 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
  22 #include "config.h"
  23 #include "cpu.h"
  24 #include "system.h"
  25 #include "kernel.h"
  26 #include "thread.h"
  27 #include "adc.h"
  28
  29 unsigned int adc_scan(int channel)
  30 {
  31     ADC_CTRL = (1<<4) | (1<<3) | (channel & (NUM_ADC_CHANNELS - 1));
  32
  33     /* wait for conversion ready ~10us */
  34     while (ADC_STAT & 0x01);
  35
  36     /* 10bits result */
  37     return (ADC_DATA & 0x3ff);
  38 }
  39
  40 void adc_init(void)
  41 {
  42     /* ADC clock divider to reach max 1MHz */
  43     SCU_DIVCON1 = (SCU_DIVCON1 & ~(0xff<<10)) | (49<<10);
  44
  45     /* enable clocks for ADC */
  46     SCU_CLKCFG |= 3<<23;
  47 }