firmware/target/coldfire/iriver/h100/adc-h100.c

   1 /***************************************************************************
   2  *             __________               __   ___.
   3  *   Open      \______   \ ____   ____ |  | _\_ |__   _______  ___
   4  *   Source     |       _//  _ \_/ ___\|  |/ /| __ \ /  _ \  \/  /
   5  *   Jukebox    |    |   (  <_> )  \___|    < | \_\ (  <_> > <  <
   6  *   Firmware   |____|_  /\____/ \___  >__|_ \|___  /\____/__/\_ \
   7  *                     \/            \/     \/    \/            \/
   8  * $Id$
   9  *
  10  * Copyright (C) 2006 by Linus Nielsen Feltzing
  11  *
  12  * All files in this archive are subject to the GNU General Public License.
  13  * See the file COPYING in the source tree root for full license agreement.
  14  *
  15  * This software is distributed on an "AS IS" basis, WITHOUT WARRANTY OF ANY
  16  * KIND, either express or implied.
  17  *
  18  ****************************************************************************/
  19 #include "config.h"
  20 #include "cpu.h"
  21 #include "system.h"
  22 #include "kernel.h"
  23 #include "thread.h"
  24 #include "adc.h"
  25
  26
  27 #define CS_LO  and_l(~0x80, &GPIO_OUT)
  28 #define CS_HI  or_l(0x80, &GPIO_OUT)
  29 #define CLK_LO and_l(~0x00400000, &GPIO_OUT)
  30 #define CLK_HI or_l(0x00400000, &GPIO_OUT)
  31 #define DO     (GPIO_READ & 0x80000000)
  32 #define DI_LO  and_l(~0x00200000, &GPIO_OUT)
  33 #define DI_HI  or_l(0x00200000, &GPIO_OUT)
  34
  35 /* delay loop */
  36 #define DELAY   \
  37     ({                                \
  38         int _x_;                      \
  39         asm volatile (                \
  40             "move.l #11, %[_x_] \r\n" \
  41         "1:                     \r\n" \
  42             "subq.l #1, %[_x_]  \r\n" \
  43             "bhi.b  1b          \r\n" \
  44             : [_x_]"=&d"(_x_)         \
  45         );                            \
  46     })
  47
  48 unsigned short adc_scan(int channel)
  49 {
  50     int level = disable_irq_save();
  51     unsigned char data = 0;
  52     int i;
  53
  54     CS_LO;
  55
  56     DI_HI;  /* Start bit */
  57     DELAY;
  58     CLK_HI;
  59     DELAY;
  60     CLK_LO;
  61
  62     DI_HI;  /* Single channel */
  63     DELAY;
  64     CLK_HI;
  65     DELAY;
  66     CLK_LO;
  67
  68     if(channel & 1) /* LSB of channel number */
  69         DI_HI;
  70     else
  71         DI_LO;
  72     DELAY;
  73     CLK_HI;
  74     DELAY;
  75     CLK_LO;
  76
  77     if(channel & 2) /* MSB of channel number */
  78         DI_HI;
  79     else
  80         DI_LO;
  81     DELAY;
  82     CLK_HI;
  83     DELAY;
  84     CLK_LO;
  85
  86     DELAY;
  87
  88     for(i = 0;i < 8;i++) /* 8 bits of data */
  89     {
  90         CLK_HI;
  91         DELAY;
  92         CLK_LO;
  93         DELAY;
  94         data <<= 1;
  95         data |= DO?1:0;
  96     }
  97
  98     CS_HI;
  99
 100     restore_irq(level);
 101     return data;
 102 }
 103
 104 void adc_init(void)
 105 {
 106     or_l(0x80600080, &GPIO_FUNCTION); /* GPIO7:  CS
 107                                          GPIO21: Data In (to the ADC)
 108                                          GPIO22: CLK
 109                                          GPIO31: Data Out (from the ADC) */
 110     or_l(0x00600080, &GPIO_ENABLE);
 111     or_l(0x80, &GPIO_OUT);          /* CS high */
 112     and_l(~0x00400000, &GPIO_OUT);  /* CLK low */
 113 }