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 "qemu/osdep.h"
  14#include "hw/ssi/ssi.h"
  15#include "qemu/module.h"
  16#include "ui/console.h"
  17
  18typedef struct {
  19    SSISlave ssidev;
  20    qemu_irq interrupt;
  21
  22    int input[8];
  23    int pressure;
  24    int noise;
  25
  26    int cycle;
  27    int output;
  28} ADS7846State;
  29
  30/* Control-byte bitfields */
  31#define CB_PD0          (1 << 0)
  32#define CB_PD1          (1 << 1)
  33#define CB_SER          (1 << 2)
  34#define CB_MODE         (1 << 3)
  35#define CB_A0           (1 << 4)
  36#define CB_A1           (1 << 5)
  37#define CB_A2           (1 << 6)
  38#define CB_START        (1 << 7)
  39
  40#define X_AXIS_DMAX     3470
  41#define X_AXIS_MIN      290
  42#define Y_AXIS_DMAX     3450
  43#define Y_AXIS_MIN      200
  44
  45#define ADS_VBAT        2000
  46#define ADS_VAUX        2000
  47#define ADS_TEMP0       2000
  48#define ADS_TEMP1       3000
  49#define ADS_XPOS(x, y)  (X_AXIS_MIN + ((X_AXIS_DMAX * (x)) >> 15))
  50#define ADS_YPOS(x, y)  (Y_AXIS_MIN + ((Y_AXIS_DMAX * (y)) >> 15))
  51#define ADS_Z1POS(x, y) 600
  52#define ADS_Z2POS(x, y) (600 + 6000 / ADS_XPOS(x, y))
  53
  54static void ads7846_int_update(ADS7846State *s)
  55{
  56    if (s->interrupt)
  57        qemu_set_irq(s->interrupt, s->pressure == 0);
  58}
  59
  60static uint32_t ads7846_transfer(SSISlave *dev, uint32_t value)
  61{
  62    ADS7846State *s = FROM_SSI_SLAVE(ADS7846State, dev);
  63
  64    switch (s->cycle ++) {
  65    case 0:
  66        if (!(value & CB_START)) {
  67            s->cycle = 0;
  68            break;
  69        }
  70
  71        s->output = s->input[(value >> 4) & 7];
  72
  73        /* Imitate the ADC noise, some drivers expect this.  */
  74        s->noise = (s->noise + 3) & 7;
  75        switch ((value >> 4) & 7) {
  76        case 1: s->output += s->noise ^ 2; break;
  77        case 3: s->output += s->noise ^ 0; break;
  78        case 4: s->output += s->noise ^ 7; break;
  79        case 5: s->output += s->noise ^ 5; break;
  80        }
  81
  82        if (value & CB_MODE)
  83            s->output >>= 4;    /* 8 bits instead of 12 */
  84
  85        break;
  86    case 1:
  87        s->cycle = 0;
  88        break;
  89    }
  90    return s->output;
  91}
  92
  93static void ads7846_ts_event(void *opaque,
  94                int x, int y, int z, int buttons_state)
  95{
  96    ADS7846State *s = opaque;
  97
  98    if (buttons_state) {
  99        x = 0x7fff - x;
 100        s->input[1] = ADS_XPOS(x, y);
 101        s->input[3] = ADS_Z1POS(x, y);
 102        s->input[4] = ADS_Z2POS(x, y);
 103        s->input[5] = ADS_YPOS(x, y);
 104    }
 105
 106    if (s->pressure == !buttons_state) {
 107        s->pressure = !!buttons_state;
 108
 109        ads7846_int_update(s);
 110    }
 111}
 112
 113static int ads7856_post_load(void *opaque, int version_id)
 114{
 115    ADS7846State *s = opaque;
 116
 117    s->pressure = 0;
 118    ads7846_int_update(s);
 119    return 0;
 120}
 121
 122static const VMStateDescription vmstate_ads7846 = {
 123    .name = "ads7846",
 124    .version_id = 1,
 125    .minimum_version_id = 1,
 126    .post_load = ads7856_post_load,
 127    .fields = (VMStateField[]) {
 128        VMSTATE_SSI_SLAVE(ssidev, ADS7846State),
 129        VMSTATE_INT32_ARRAY(input, ADS7846State, 8),
 130        VMSTATE_INT32(noise, ADS7846State),
 131        VMSTATE_INT32(cycle, ADS7846State),
 132        VMSTATE_INT32(output, ADS7846State),
 133        VMSTATE_END_OF_LIST()
 134    }
 135};
 136
 137static void ads7846_realize(SSISlave *d, Error **errp)
 138{
 139    DeviceState *dev = DEVICE(d);
 140    ADS7846State *s = FROM_SSI_SLAVE(ADS7846State, d);
 141
 142    qdev_init_gpio_out(dev, &s->interrupt, 1);
 143
 144    s->input[0] = ADS_TEMP0;    /* TEMP0 */
 145    s->input[2] = ADS_VBAT;     /* VBAT */
 146    s->input[6] = ADS_VAUX;     /* VAUX */
 147    s->input[7] = ADS_TEMP1;    /* TEMP1 */
 148
 149    /* We want absolute coordinates */
 150    qemu_add_mouse_event_handler(ads7846_ts_event, s, 1,
 151                    "QEMU ADS7846-driven Touchscreen");
 152
 153    ads7846_int_update(s);
 154
 155    vmstate_register(NULL, -1, &vmstate_ads7846, s);
 156}
 157
 158static void ads7846_class_init(ObjectClass *klass, void *data)
 159{
 160    SSISlaveClass *k = SSI_SLAVE_CLASS(klass);
 161
 162    k->realize = ads7846_realize;
 163    k->transfer = ads7846_transfer;
 164}
 165
 166static const TypeInfo ads7846_info = {
 167    .name          = "ads7846",
 168    .parent        = TYPE_SSI_SLAVE,
 169    .instance_size = sizeof(ADS7846State),
 170    .class_init    = ads7846_class_init,
 171};
 172
 173static void ads7846_register_types(void)
 174{
 175    type_register_static(&ads7846_info);
 176}
 177
 178type_init(ads7846_register_types)
 179