firmware/target/arm/ipod/adc-ipod-pcf.c

   1 /***************************************************************************
   2  *             __________               __   ___.
   3  *   Open      \______   \ ____   ____ |  | _\_ |__   _______  ___
   4  *   Source     |       _//  _ \_/ ___\|  |/ /| __ \ /  _ \  \/  /
   5  *   Jukebox    |    |   (  <_> )  \___|    < | \_\ (  <_> > <  <
   6  *   Firmware   |____|_  /\____/ \___  >__|_ \|___  /\____/__/\_ \
   7  *                     \/            \/     \/    \/            \/
   8  * $Id$
   9  *
  10  * Copyright (C) 2002 by Linus Nielsen Feltzing
  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 "config.h"
  22 #include "cpu.h"
  23 #include "system.h"
  24 #include "kernel.h"
  25 #include "thread.h"
  26 #include "string.h"
  27 #include "adc.h"
  28 #include "pcf50605.h"
  29 #include "i2c-pp.h"
  30
  31 struct adc_struct {
  32     long timeout;
  33     void (*conversion)(unsigned short *data);
  34     short channelnum;
  35     unsigned short data;
  36 };
  37
  38 static struct adc_struct adcdata[NUM_ADC_CHANNELS] IDATA_ATTR;
  39
  40 static unsigned short _adc_read(struct adc_struct *adc)
  41 {
  42     if (TIME_AFTER(current_tick, adc->timeout)) {
  43         unsigned char data[2];
  44         unsigned short value;
  45
  46         i2c_lock();
  47
  48         /* 5x per 2 seconds */
  49         adc->timeout = current_tick + (HZ * 2 / 5);
  50
  51         /* ADCC1, 10 bit, start */
  52         pcf50605_write(0x2f, (adc->channelnum << 1) | 0x1);
  53         pcf50605_read_multiple(0x30, data, 2); /* ADCS1, ADCS2 */
  54         value   = data[0];
  55         value <<= 2;
  56         value  |= data[1] & 0x3;
  57
  58         if (adc->conversion) {
  59             adc->conversion(&value);
  60         }
  61         adc->data = value;
  62
  63         i2c_unlock();
  64         return value;
  65     } else
  66     {
  67         return adc->data;
  68     }
  69 }
  70
  71 /* Force an ADC scan _now_ */
  72 unsigned short adc_scan(int channel) {
  73     struct adc_struct *adc = &adcdata[channel];
  74     adc->timeout = 0;
  75     return _adc_read(adc);
  76 }
  77
  78 /* Retrieve the ADC value, only does a scan periodically */
  79 unsigned short adc_read(int channel) {
  80     return _adc_read(&adcdata[channel]);
  81 }
  82
  83 void adc_init(void)
  84 {
  85     struct adc_struct *adc_battery = &adcdata[ADC_BATTERY];
  86     adc_battery->channelnum = 0x2; /* ADCVIN1, resistive divider */
  87     adc_battery->timeout = 0;
  88     adcdata[ADC_ACCESSORY].channelnum = 4;
  89     adcdata[ADC_ACCESSORY].timeout = 0;
  90 #ifdef IPOD_VIDEO
  91     adcdata[ADC_4066_ISTAT].channelnum = 7;
  92     adcdata[ADC_4066_ISTAT].timeout = 0;
  93 #endif
  94     _adc_read(adc_battery);
  95 }