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 "ssi.h"
  11
  12 typedef struct {
  13     SSISlave ssidev;
  14     qemu_irq interrupt;
  15     uint8_t tb1, rb2, rb3;
  16     int cycle;
  17
  18     int input[8];
  19     int inputs, com;
  20 } MAX111xState;
  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 static uint32_t max111x_read(MAX111xState *s)
  38 {
  39     if (!s->tb1)
  40         return 0;
  41
  42     switch (s->cycle ++) {
  43     case 1:
  44         return s->rb2;
  45     case 2:
  46         return s->rb3;
  47     }
  48
  49     return 0;
  50 }
  51
  52 /* Interpret a control-byte */
  53 static void max111x_write(MAX111xState *s, uint32_t value)
  54 {
  55     int measure, chan;
  56
  57     /* Ignore the value if START bit is zero */
  58     if (!(value & CB_START))
  59         return;
  60
  61     s->cycle = 0;
  62
  63     if (!(value & CB_PD1)) {
  64         s->tb1 = 0;
  65         return;
  66     }
  67
  68     s->tb1 = value;
  69
  70     if (s->inputs == 8)
  71         chan = CHANNEL_NUM(value, 1, 0, 2);
  72     else
  73         chan = CHANNEL_NUM(value & ~CB_SEL0, 0, 1, 2);
  74
  75     if (value & CB_SGL)
  76         measure = s->input[chan] - s->com;
  77     else
  78         measure = s->input[chan] - s->input[chan ^ 1];
  79
  80     if (!(value & CB_UNI))
  81         measure ^= 0x80;
  82
  83     s->rb2 = (measure >> 2) & 0x3f;
  84     s->rb3 = (measure << 6) & 0xc0;
  85
  86     /* FIXME: When should the IRQ be lowered?  */
  87     qemu_irq_raise(s->interrupt);
  88 }
  89
  90 static uint32_t max111x_transfer(SSISlave *dev, uint32_t value)
  91 {
  92     MAX111xState *s = FROM_SSI_SLAVE(MAX111xState, dev);
  93     max111x_write(s, value);
  94     return max111x_read(s);
  95 }
  96
  97 static void max111x_save(QEMUFile *f, void *opaque)
  98 {
  99     MAX111xState *s = (MAX111xState *) opaque;
 100     int i;
 101
 102     qemu_put_8s(f, &s->tb1);
 103     qemu_put_8s(f, &s->rb2);
 104     qemu_put_8s(f, &s->rb3);
 105     qemu_put_be32(f, s->inputs);
 106     qemu_put_be32(f, s->com);
 107     for (i = 0; i < s->inputs; i ++)
 108         qemu_put_byte(f, s->input[i]);
 109 }
 110
 111 static int max111x_load(QEMUFile *f, void *opaque, int version_id)
 112 {
 113     MAX111xState *s = (MAX111xState *) opaque;
 114     int i;
 115
 116     qemu_get_8s(f, &s->tb1);
 117     qemu_get_8s(f, &s->rb2);
 118     qemu_get_8s(f, &s->rb3);
 119     if (s->inputs != qemu_get_be32(f))
 120         return -EINVAL;
 121     s->com = qemu_get_be32(f);
 122     for (i = 0; i < s->inputs; i ++)
 123         s->input[i] = qemu_get_byte(f);
 124
 125     return 0;
 126 }
 127
 128 static void max111x_init(SSISlave *dev, int inputs)
 129 {
 130     MAX111xState *s = FROM_SSI_SLAVE(MAX111xState, dev);
 131
 132     qdev_init_gpio_out(&dev->qdev, &s->interrupt, 1);
 133
 134     s->inputs = inputs;
 135     /* TODO: add a user interface for setting these */
 136     s->input[0] = 0xf0;
 137     s->input[1] = 0xe0;
 138     s->input[2] = 0xd0;
 139     s->input[3] = 0xc0;
 140     s->input[4] = 0xb0;
 141     s->input[5] = 0xa0;
 142     s->input[6] = 0x90;
 143     s->input[7] = 0x80;
 144     s->com = 0;
 145
 146     register_savevm("max111x", -1, 0, max111x_save, max111x_load, s);
 147 }
 148
 149 static void max1110_init(SSISlave *dev)
 150 {
 151     max111x_init(dev, 8);
 152 }
 153
 154 static void max1111_init(SSISlave *dev)
 155 {
 156     max111x_init(dev, 4);
 157 }
 158
 159 void max111x_set_input(DeviceState *dev, int line, uint8_t value)
 160 {
 161     MAX111xState *s = FROM_SSI_SLAVE(MAX111xState, SSI_SLAVE_FROM_QDEV(dev));
 162     assert(line >= 0 && line < s->inputs);
 163     s->input[line] = value;
 164 }
 165
 166 static SSISlaveInfo max1110_info = {
 167     .init = max1110_init,
 168     .transfer = max111x_transfer
 169 };
 170
 171 static SSISlaveInfo max1111_info = {
 172     .init = max1111_init,
 173     .transfer = max111x_transfer
 174 };
 175
 176 static void max111x_register_devices(void)
 177 {
 178     ssi_register_slave("max1110", sizeof(MAX111xState), &max1110_info);
 179     ssi_register_slave("max1111", sizeof(MAX111xState), &max1111_info);
 180 }
 181
 182 device_init(max111x_register_devices)