firmware/target/arm/imx31/gigabeat-s/adc-imx31.c

   1 /***************************************************************************
   2  *             __________               __   ___.
   3  *   Open      \______   \ ____   ____ |  | _\_ |__   _______  ___
   4  *   Source     |       _//  _ \_/ ___\|  |/ /| __ \ /  _ \  \/  /
   5  *   Jukebox    |    |   (  <_> )  \___|    < | \_\ (  <_> > <  <
   6  *   Firmware   |____|_  /\____/ \___  >__|_ \|___  /\____/__/\_ \
   7  *                     \/            \/     \/    \/            \/
   8  * $Id$
   9  *
  10  * Copyright (C) 2008 by Michael Sevakis
  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 "system.h"
  23 #include "mc13783.h"
  24 #include "adc.h"
  25 #include "adc-target.h"
  26 #include "kernel.h"
  27
  28 /* Do this so we may read all channels in a single SPI message */
  29 static const unsigned char reg_array[4] =
  30 {
  31     MC13783_ADC2,
  32     MC13783_ADC2,
  33     MC13783_ADC2,
  34     MC13783_ADC2,
  35 };
  36
  37 static uint32_t channels[2][4];
  38 static struct wakeup adc_wake;
  39 static struct mutex adc_mtx;
  40 static long last_adc_read[2]; /* One for each input group */
  41
  42 /* Read 10-bit ADC channel */
  43 unsigned short adc_read(int channel)
  44 {
  45     uint32_t data;
  46     int input_select;
  47
  48     if ((unsigned)channel >= NUM_ADC_CHANNELS)
  49         return ADC_READ_ERROR;
  50
  51     input_select = channel >> 3;
  52
  53     mutex_lock(&adc_mtx);
  54
  55     /* Limit the traffic through here */
  56     if (current_tick != last_adc_read[input_select])
  57     {
  58         /* Keep enable, start conversion, increment from channel 0,
  59          * increment from channel 4 */
  60         uint32_t adc1 = MC13783_ADEN | MC13783_ASC |
  61                         (0 << MC13783_ADA1_POS) | (4 << MC13783_ADA2_POS);
  62
  63         if (input_select == 1)
  64             adc1 |= MC13783_ADSEL; /* 2nd set of inputs */
  65
  66         /* Start conversion */
  67         mc13783_write(MC13783_ADC1, adc1);
  68
  69         /* Wait for done signal */
  70         wakeup_wait(&adc_wake, TIMEOUT_BLOCK);
  71
  72         /* Read all 8 channels that are converted - two channels in each
  73          * word. */
  74         mc13783_read_regset(reg_array, channels[input_select], 4);
  75
  76         last_adc_read[input_select] = current_tick;
  77     }
  78
  79     data = channels[input_select][channel & 3];
  80
  81     mutex_unlock(&adc_mtx);
  82
  83     /* Channels 0-3/8-11 in ADD1, 4-7/12-15 in ADD2 */
  84     return (channel & 4) ?
  85         ((data & MC13783_ADD2) >> MC13783_ADD2_POS) :
  86         ((data & MC13783_ADD1) >> MC13783_ADD1_POS);
  87 }
  88
  89 bool adc_enable_channel(int channel, bool enable)
  90 {
  91     uint32_t bit, mask;
  92
  93     switch (channel)
  94     {
  95     case ADC_CHARGER_CURRENT:
  96         mask = MC13783_CHRGICON;
  97         break;
  98
  99     case ADC_BATTERY_TEMP:
 100         mask = MC13783_RTHEN;
 101         break;
 102
 103     default:
 104         return false;
 105     }
 106
 107     bit = enable ? mask : 0;
 108
 109     return mc13783_write_masked(MC13783_ADC0, bit, mask)
 110                 != MC13783_DATA_ERROR;
 111 }
 112
 113 /* Called by mc13783 interrupt thread when conversion is complete */
 114 void adc_done(void)
 115 {
 116     wakeup_signal(&adc_wake);
 117 }
 118
 119 void adc_init(void)
 120 {
 121     wakeup_init(&adc_wake);
 122     mutex_init(&adc_mtx);
 123
 124     /* Init so first reads get data */
 125     last_adc_read[0] = last_adc_read[1] = current_tick-1;
 126
 127     /* Enable increment-by-read, turn off extra conversions. */
 128     mc13783_write(MC13783_ADC0, MC13783_ADINC2 | MC13783_ADINC1);
 129
 130     /* Enable ADC, set multi-channel mode */
 131     mc13783_write(MC13783_ADC1, MC13783_ADEN);
 132
 133     /* Enable ADCDONE event */
 134     mc13783_write(MC13783_INTERRUPT_STATUS0, MC13783_ADCDONEI);
 135     mc13783_enable_event(MC13783_ADCDONE_EVENT);
 136 }