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