LXR qemu/hw/display/ads7846.c

   1/*
   2 * TI ADS7846 / TSC2046 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 GPL v2.
   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 "hw/ssi.h"
  14#include "ui/console.h"
  15
  16typedef struct {
  17    SSISlave ssidev;
  18    qemu_irq interrupt;
  19
  20    int input[8];
  21    int pressure;
  22    int noise;
  23
  24    int cycle;
  25    int output;
  26} ADS7846State;
  27
  28/* Control-byte bitfields */
  29#define CB_PD0          (1 << 0)
  30#define CB_PD1          (1 << 1)
  31#define CB_SER          (1 << 2)
  32#define CB_MODE         (1 << 3)
  33#define CB_A0           (1 << 4)
  34#define CB_A1           (1 << 5)
  35#define CB_A2           (1 << 6)
  36#define CB_START        (1 << 7)
  37
  38#define X_AXIS_DMAX     3470
  39#define X_AXIS_MIN      290
  40#define Y_AXIS_DMAX     3450
  41#define Y_AXIS_MIN      200
  42
  43#define ADS_VBAT        2000
  44#define ADS_VAUX        2000
  45#define ADS_TEMP0       2000
  46#define ADS_TEMP1       3000
  47#define ADS_XPOS(x, y)  (X_AXIS_MIN + ((X_AXIS_DMAX * (x)) >> 15))
  48#define ADS_YPOS(x, y)  (Y_AXIS_MIN + ((Y_AXIS_DMAX * (y)) >> 15))
  49#define ADS_Z1POS(x, y) 600
  50#define ADS_Z2POS(x, y) (600 + 6000 / ADS_XPOS(x, y))
  51
  52static void ads7846_int_update(ADS7846State *s)
  53{
  54    if (s->interrupt)
  55        qemu_set_irq(s->interrupt, s->pressure == 0);
  56}
  57
  58static uint32_t ads7846_transfer(SSISlave *dev, uint32_t value)
  59{
  60    ADS7846State *s = FROM_SSI_SLAVE(ADS7846State, dev);
  61
  62    switch (s->cycle ++) {
  63    case 0:
  64        if (!(value & CB_START)) {
  65            s->cycle = 0;
  66            break;
  67        }
  68
  69        s->output = s->input[(value >> 4) & 7];
  70
  71        /* Imitate the ADC noise, some drivers expect this.  */
  72        s->noise = (s->noise + 3) & 7;
  73        switch ((value >> 4) & 7) {
  74        case 1: s->output += s->noise ^ 2; break;
  75        case 3: s->output += s->noise ^ 0; break;
  76        case 4: s->output += s->noise ^ 7; break;
  77        case 5: s->output += s->noise ^ 5; break;
  78        }
  79
  80        if (value & CB_MODE)
  81            s->output >>= 4;    /* 8 bits instead of 12 */
  82
  83        break;
  84    case 1:
  85        s->cycle = 0;
  86        break;
  87    }
  88    return s->output;
  89}
  90
  91static void ads7846_ts_event(void *opaque,
  92                int x, int y, int z, int buttons_state)
  93{
  94    ADS7846State *s = opaque;
  95
  96    if (buttons_state) {
  97        x = 0x7fff - x;
  98        s->input[1] = ADS_XPOS(x, y);
  99        s->input[3] = ADS_Z1POS(x, y);
 100        s->input[4] = ADS_Z2POS(x, y);
 101        s->input[5] = ADS_YPOS(x, y);
 102    }
 103
 104    if (s->pressure == !buttons_state) {
 105        s->pressure = !!buttons_state;
 106
 107        ads7846_int_update(s);
 108    }
 109}
 110
 111static int ads7856_post_load(void *opaque, int version_id)
 112{
 113    ADS7846State *s = opaque;
 114
 115    s->pressure = 0;
 116    ads7846_int_update(s);
 117    return 0;
 118}
 119
 120static const VMStateDescription vmstate_ads7846 = {
 121    .name = "ads7846",
 122    .version_id = 1,
 123    .minimum_version_id = 1,
 124    .minimum_version_id_old = 1,
 125    .post_load = ads7856_post_load,
 126    .fields      = (VMStateField[]) {
 127        VMSTATE_SSI_SLAVE(ssidev, ADS7846State),
 128        VMSTATE_INT32_ARRAY(input, ADS7846State, 8),
 129        VMSTATE_INT32(noise, ADS7846State),
 130        VMSTATE_INT32(cycle, ADS7846State),
 131        VMSTATE_INT32(output, ADS7846State),
 132        VMSTATE_END_OF_LIST()
 133    }
 134};
 135
 136static int ads7846_init(SSISlave *dev)
 137{
 138    ADS7846State *s = FROM_SSI_SLAVE(ADS7846State, dev);
 139
 140    qdev_init_gpio_out(&dev->qdev, &s->interrupt, 1);
 141
 142    s->input[0] = ADS_TEMP0;    /* TEMP0 */
 143    s->input[2] = ADS_VBAT;     /* VBAT */
 144    s->input[6] = ADS_VAUX;     /* VAUX */
 145    s->input[7] = ADS_TEMP1;    /* TEMP1 */
 146
 147    /* We want absolute coordinates */
 148    qemu_add_mouse_event_handler(ads7846_ts_event, s, 1,
 149                    "QEMU ADS7846-driven Touchscreen");
 150
 151    ads7846_int_update(s);
 152
 153    vmstate_register(NULL, -1, &vmstate_ads7846, s);
 154    return 0;
 155}
 156
 157static void ads7846_class_init(ObjectClass *klass, void *data)
 158{
 159    SSISlaveClass *k = SSI_SLAVE_CLASS(klass);
 160
 161    k->init = ads7846_init;
 162    k->transfer = ads7846_transfer;
 163}
 164
 165static const TypeInfo ads7846_info = {
 166    .name          = "ads7846",
 167    .parent        = TYPE_SSI_SLAVE,
 168    .instance_size = sizeof(ADS7846State),
 169    .class_init    = ads7846_class_init,
 170};
 171
 172static void ads7846_register_types(void)
 173{
 174    type_register_static(&ads7846_info);
 175}
 176
 177type_init(ads7846_register_types)
 178