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
  18 typedef 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
  54 static void ads7846_int_update(ADS7846State *s)
  55 {
  56     if (s->interrupt)
  57         qemu_set_irq(s->interrupt, s->pressure == 0);
  58 }
  59
  60 static 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
  93 static 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
 113 static 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
 122 static 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
 137 static 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
 158 static 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
 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)