hw/max111x.c

   1 /*
   2  * Maxim MAX1110/1111 ADC chip emulation.
   3  *
   4  * Copyright (c) 2006 Openedhand Ltd.
   5  * Written by Andrzej Zaborowski <balrog@zabor.org>
   6  *
   7  * This code is licensed under the GNU GPLv2.
   8  */
   9
  10 #include "hw.h"
  11 #include "i2c.h"
  12
  13 struct max111x_s {
  14     qemu_irq interrupt;
  15     uint8_t tb1, rb2, rb3;
  16     int cycle;
  17
  18     int input[8];
  19     int inputs, com;
  20 };
  21
  22 /* Control-byte bitfields */
  23 #define CB_PD0          (1 << 0)
  24 #define CB_PD1          (1 << 1)
  25 #define CB_SGL          (1 << 2)
  26 #define CB_UNI          (1 << 3)
  27 #define CB_SEL0         (1 << 4)
  28 #define CB_SEL1         (1 << 5)
  29 #define CB_SEL2         (1 << 6)
  30 #define CB_START        (1 << 7)
  31
  32 #define CHANNEL_NUM(v, b0, b1, b2)      \
  33                         ((((v) >> (2 + (b0))) & 4) |    \
  34                          (((v) >> (3 + (b1))) & 2) |    \
  35                          (((v) >> (4 + (b2))) & 1))
  36
  37 uint32_t max111x_read(void *opaque)
  38 {
  39     struct max111x_s *s = (struct max111x_s *) opaque;
  40
  41     if (!s->tb1)
  42         return 0;
  43
  44     switch (s->cycle ++) {
  45     case 1:
  46         return s->rb2;
  47     case 2:
  48         return s->rb3;
  49     }
  50
  51     return 0;
  52 }
  53
  54 /* Interpret a control-byte */
  55 void max111x_write(void *opaque, uint32_t value)
  56 {
  57     struct max111x_s *s = (struct max111x_s *) opaque;
  58     int measure, chan;
  59
  60     /* Ignore the value if START bit is zero */
  61     if (!(value & CB_START))
  62         return;
  63
  64     s->cycle = 0;
  65
  66     if (!(value & CB_PD1)) {
  67         s->tb1 = 0;
  68         return;
  69     }
  70
  71     s->tb1 = value;
  72
  73     if (s->inputs == 8)
  74         chan = CHANNEL_NUM(value, 1, 0, 2);
  75     else
  76         chan = CHANNEL_NUM(value & ~CB_SEL0, 0, 1, 2);
  77
  78     if (value & CB_SGL)
  79         measure = s->input[chan] - s->com;
  80     else
  81         measure = s->input[chan] - s->input[chan ^ 1];
  82
  83     if (!(value & CB_UNI))
  84         measure ^= 0x80;
  85
  86     s->rb2 = (measure >> 2) & 0x3f;
  87     s->rb3 = (measure << 6) & 0xc0;
  88
  89     if (s->interrupt)
  90         qemu_irq_raise(s->interrupt);
  91 }
  92
  93 static void max111x_save(QEMUFile *f, void *opaque)
  94 {
  95     struct max111x_s *s = (struct max111x_s *) opaque;
  96     int i;
  97
  98     qemu_put_8s(f, &s->tb1);
  99     qemu_put_8s(f, &s->rb2);
 100     qemu_put_8s(f, &s->rb3);
 101     qemu_put_be32(f, s->inputs);
 102     qemu_put_be32(f, s->com);
 103     for (i = 0; i < s->inputs; i ++)
 104         qemu_put_byte(f, s->input[i]);
 105 }
 106
 107 static int max111x_load(QEMUFile *f, void *opaque, int version_id)
 108 {
 109     struct max111x_s *s = (struct max111x_s *) opaque;
 110     int i;
 111
 112     qemu_get_8s(f, &s->tb1);
 113     qemu_get_8s(f, &s->rb2);
 114     qemu_get_8s(f, &s->rb3);
 115     if (s->inputs != qemu_get_be32(f))
 116         return -EINVAL;
 117     s->com = qemu_get_be32(f);
 118     for (i = 0; i < s->inputs; i ++)
 119         s->input[i] = qemu_get_byte(f);
 120
 121     return 0;
 122 }
 123
 124 static struct max111x_s *max111x_init(qemu_irq cb)
 125 {
 126     struct max111x_s *s;
 127     s = (struct max111x_s *)
 128             qemu_mallocz(sizeof(struct max111x_s));
 129     memset(s, 0, sizeof(struct max111x_s));
 130
 131     s->interrupt = cb;
 132
 133     /* TODO: add a user interface for setting these */
 134     s->input[0] = 0xf0;
 135     s->input[1] = 0xe0;
 136     s->input[2] = 0xd0;
 137     s->input[3] = 0xc0;
 138     s->input[4] = 0xb0;
 139     s->input[5] = 0xa0;
 140     s->input[6] = 0x90;
 141     s->input[7] = 0x80;
 142     s->com = 0;
 143
 144     register_savevm("max111x", -1, 0, max111x_save, max111x_load, s);
 145
 146     return s;
 147 }
 148
 149 struct max111x_s *max1110_init(qemu_irq cb)
 150 {
 151     struct max111x_s *s = max111x_init(cb);
 152     s->inputs = 8;
 153     return s;
 154 }
 155
 156 struct max111x_s *max1111_init(qemu_irq cb)
 157 {
 158     struct max111x_s *s = max111x_init(cb);
 159     s->inputs = 4;
 160     return s;
 161 }
 162
 163 void max111x_set_input(struct max111x_s *s, int line, uint8_t value)
 164 {
 165     if (line >= s->inputs) {
 166         printf("%s: There's no input %i\n", __FUNCTION__, line);
 167         return;
 168     }
 169
 170     s->input[line] = value;
 171 }