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  * Contributions after 2012-01-13 are licensed under the terms of the
  10  * GNU GPL, version 2 or (at your option) any later version.
  11  */
  12
  13 #include "ssi.h"
  14
  15 typedef struct {
  16     SSISlave ssidev;
  17     qemu_irq interrupt;
  18     uint8_t tb1, rb2, rb3;
  19     int cycle;
  20
  21     uint8_t input[8];
  22     int inputs, com;
  23 } MAX111xState;
  24
  25 /* Control-byte bitfields */
  26 #define CB_PD0          (1 << 0)
  27 #define CB_PD1          (1 << 1)
  28 #define CB_SGL          (1 << 2)
  29 #define CB_UNI          (1 << 3)
  30 #define CB_SEL0         (1 << 4)
  31 #define CB_SEL1         (1 << 5)
  32 #define CB_SEL2         (1 << 6)
  33 #define CB_START        (1 << 7)
  34
  35 #define CHANNEL_NUM(v, b0, b1, b2)      \
  36                         ((((v) >> (2 + (b0))) & 4) |    \
  37                          (((v) >> (3 + (b1))) & 2) |    \
  38                          (((v) >> (4 + (b2))) & 1))
  39
  40 static uint32_t max111x_read(MAX111xState *s)
  41 {
  42     if (!s->tb1)
  43         return 0;
  44
  45     switch (s->cycle ++) {
  46     case 1:
  47         return s->rb2;
  48     case 2:
  49         return s->rb3;
  50     }
  51
  52     return 0;
  53 }
  54
  55 /* Interpret a control-byte */
  56 static void max111x_write(MAX111xState *s, uint32_t value)
  57 {
  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     /* FIXME: When should the IRQ be lowered?  */
  90     qemu_irq_raise(s->interrupt);
  91 }
  92
  93 static uint32_t max111x_transfer(SSISlave *dev, uint32_t value)
  94 {
  95     MAX111xState *s = FROM_SSI_SLAVE(MAX111xState, dev);
  96     max111x_write(s, value);
  97     return max111x_read(s);
  98 }
  99
 100 static const VMStateDescription vmstate_max111x = {
 101     .name = "max111x",
 102     .version_id = 0,
 103     .minimum_version_id = 0,
 104     .minimum_version_id_old = 0,
 105     .fields      = (VMStateField[]) {
 106         VMSTATE_UINT8(tb1, MAX111xState),
 107         VMSTATE_UINT8(rb2, MAX111xState),
 108         VMSTATE_UINT8(rb3, MAX111xState),
 109         VMSTATE_INT32_EQUAL(inputs, MAX111xState),
 110         VMSTATE_INT32(com, MAX111xState),
 111         VMSTATE_ARRAY_INT32_UNSAFE(input, MAX111xState, inputs,
 112                                    vmstate_info_uint8, uint8_t),
 113         VMSTATE_END_OF_LIST()
 114     }
 115 };
 116
 117 static int max111x_init(SSISlave *dev, int inputs)
 118 {
 119     MAX111xState *s = FROM_SSI_SLAVE(MAX111xState, dev);
 120
 121     qdev_init_gpio_out(&dev->qdev, &s->interrupt, 1);
 122
 123     s->inputs = inputs;
 124     /* TODO: add a user interface for setting these */
 125     s->input[0] = 0xf0;
 126     s->input[1] = 0xe0;
 127     s->input[2] = 0xd0;
 128     s->input[3] = 0xc0;
 129     s->input[4] = 0xb0;
 130     s->input[5] = 0xa0;
 131     s->input[6] = 0x90;
 132     s->input[7] = 0x80;
 133     s->com = 0;
 134
 135     vmstate_register(&dev->qdev, -1, &vmstate_max111x, s);
 136     return 0;
 137 }
 138
 139 static int max1110_init(SSISlave *dev)
 140 {
 141     return max111x_init(dev, 8);
 142 }
 143
 144 static int max1111_init(SSISlave *dev)
 145 {
 146     return max111x_init(dev, 4);
 147 }
 148
 149 void max111x_set_input(DeviceState *dev, int line, uint8_t value)
 150 {
 151     MAX111xState *s = FROM_SSI_SLAVE(MAX111xState, SSI_SLAVE_FROM_QDEV(dev));
 152     assert(line >= 0 && line < s->inputs);
 153     s->input[line] = value;
 154 }
 155
 156 static void max1110_class_init(ObjectClass *klass, void *data)
 157 {
 158     SSISlaveClass *k = SSI_SLAVE_CLASS(klass);
 159
 160     k->init = max1110_init;
 161     k->transfer = max111x_transfer;
 162 }
 163
 164 static DeviceInfo max1110_info = {
 165     .name = "max1110",
 166     .size = sizeof(MAX111xState),
 167     .class_init = max1110_class_init,
 168 };
 169
 170 static void max1111_class_init(ObjectClass *klass, void *data)
 171 {
 172     SSISlaveClass *k = SSI_SLAVE_CLASS(klass);
 173
 174     k->init = max1111_init;
 175     k->transfer = max111x_transfer;
 176 }
 177
 178 static DeviceInfo max1111_info = {
 179     .name = "max1111",
 180     .size = sizeof(MAX111xState),
 181     .class_init = max1111_class_init,
 182 };
 183
 184 static void max111x_register_devices(void)
 185 {
 186     ssi_register_slave(&max1110_info);
 187     ssi_register_slave(&max1111_info);
 188 }
 189
 190 device_init(max111x_register_devices)