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/irq.h"
  15 #include "hw/ssi/ssi.h"
  16 #include "migration/vmstate.h"
  17 #include "qemu/module.h"
  18 #include "ui/console.h"
  19 #include "qom/object.h"
  20
  21 struct ADS7846State {
  22     SSISlave ssidev;
  23     qemu_irq interrupt;
  24
  25     int input[8];
  26     int pressure;
  27     int noise;
  28
  29     int cycle;
  30     int output;
  31 };
  32 typedef struct ADS7846State ADS7846State;
  33
  34 #define TYPE_ADS7846 "ads7846"
  35 DECLARE_INSTANCE_CHECKER(ADS7846State, ADS7846,
  36                          TYPE_ADS7846)
  37
  38 /* Control-byte bitfields */
  39 #define CB_PD0          (1 << 0)
  40 #define CB_PD1          (1 << 1)
  41 #define CB_SER          (1 << 2)
  42 #define CB_MODE         (1 << 3)
  43 #define CB_A0           (1 << 4)
  44 #define CB_A1           (1 << 5)
  45 #define CB_A2           (1 << 6)
  46 #define CB_START        (1 << 7)
  47
  48 #define X_AXIS_DMAX     3470
  49 #define X_AXIS_MIN      290
  50 #define Y_AXIS_DMAX     3450
  51 #define Y_AXIS_MIN      200
  52
  53 #define ADS_VBAT        2000
  54 #define ADS_VAUX        2000
  55 #define ADS_TEMP0       2000
  56 #define ADS_TEMP1       3000
  57 #define ADS_XPOS(x, y)  (X_AXIS_MIN + ((X_AXIS_DMAX * (x)) >> 15))
  58 #define ADS_YPOS(x, y)  (Y_AXIS_MIN + ((Y_AXIS_DMAX * (y)) >> 15))
  59 #define ADS_Z1POS(x, y) 600
  60 #define ADS_Z2POS(x, y) (600 + 6000 / ADS_XPOS(x, y))
  61
  62 static void ads7846_int_update(ADS7846State *s)
  63 {
  64     if (s->interrupt)
  65         qemu_set_irq(s->interrupt, s->pressure == 0);
  66 }
  67
  68 static uint32_t ads7846_transfer(SSISlave *dev, uint32_t value)
  69 {
  70     ADS7846State *s = ADS7846(dev);
  71
  72     switch (s->cycle ++) {
  73     case 0:
  74         if (!(value & CB_START)) {
  75             s->cycle = 0;
  76             break;
  77         }
  78
  79         s->output = s->input[(value >> 4) & 7];
  80
  81         /* Imitate the ADC noise, some drivers expect this.  */
  82         s->noise = (s->noise + 3) & 7;
  83         switch ((value >> 4) & 7) {
  84         case 1: s->output += s->noise ^ 2; break;
  85         case 3: s->output += s->noise ^ 0; break;
  86         case 4: s->output += s->noise ^ 7; break;
  87         case 5: s->output += s->noise ^ 5; break;
  88         }
  89
  90         if (value & CB_MODE)
  91             s->output >>= 4;    /* 8 bits instead of 12 */
  92
  93         break;
  94     case 1:
  95         s->cycle = 0;
  96         break;
  97     }
  98     return s->output;
  99 }
 100
 101 static void ads7846_ts_event(void *opaque,
 102                 int x, int y, int z, int buttons_state)
 103 {
 104     ADS7846State *s = opaque;
 105
 106     if (buttons_state) {
 107         x = 0x7fff - x;
 108         s->input[1] = ADS_XPOS(x, y);
 109         s->input[3] = ADS_Z1POS(x, y);
 110         s->input[4] = ADS_Z2POS(x, y);
 111         s->input[5] = ADS_YPOS(x, y);
 112     }
 113
 114     if (s->pressure == !buttons_state) {
 115         s->pressure = !!buttons_state;
 116
 117         ads7846_int_update(s);
 118     }
 119 }
 120
 121 static int ads7856_post_load(void *opaque, int version_id)
 122 {
 123     ADS7846State *s = opaque;
 124
 125     s->pressure = 0;
 126     ads7846_int_update(s);
 127     return 0;
 128 }
 129
 130 static const VMStateDescription vmstate_ads7846 = {
 131     .name = "ads7846",
 132     .version_id = 1,
 133     .minimum_version_id = 1,
 134     .post_load = ads7856_post_load,
 135     .fields = (VMStateField[]) {
 136         VMSTATE_SSI_SLAVE(ssidev, ADS7846State),
 137         VMSTATE_INT32_ARRAY(input, ADS7846State, 8),
 138         VMSTATE_INT32(noise, ADS7846State),
 139         VMSTATE_INT32(cycle, ADS7846State),
 140         VMSTATE_INT32(output, ADS7846State),
 141         VMSTATE_END_OF_LIST()
 142     }
 143 };
 144
 145 static void ads7846_realize(SSISlave *d, Error **errp)
 146 {
 147     DeviceState *dev = DEVICE(d);
 148     ADS7846State *s = ADS7846(d);
 149
 150     qdev_init_gpio_out(dev, &s->interrupt, 1);
 151
 152     s->input[0] = ADS_TEMP0;    /* TEMP0 */
 153     s->input[2] = ADS_VBAT;     /* VBAT */
 154     s->input[6] = ADS_VAUX;     /* VAUX */
 155     s->input[7] = ADS_TEMP1;    /* TEMP1 */
 156
 157     /* We want absolute coordinates */
 158     qemu_add_mouse_event_handler(ads7846_ts_event, s, 1,
 159                     "QEMU ADS7846-driven Touchscreen");
 160
 161     ads7846_int_update(s);
 162
 163     vmstate_register(NULL, VMSTATE_INSTANCE_ID_ANY, &vmstate_ads7846, s);
 164 }
 165
 166 static void ads7846_class_init(ObjectClass *klass, void *data)
 167 {
 168     SSISlaveClass *k = SSI_SLAVE_CLASS(klass);
 169
 170     k->realize = ads7846_realize;
 171     k->transfer = ads7846_transfer;
 172 }
 173
 174 static const TypeInfo ads7846_info = {
 175     .name          = TYPE_ADS7846,
 176     .parent        = TYPE_SSI_SLAVE,
 177     .instance_size = sizeof(ADS7846State),
 178     .class_init    = ads7846_class_init,
 179 };
 180
 181 static void ads7846_register_types(void)
 182 {
 183     type_register_static(&ads7846_info);
 184 }
 185
 186 type_init(ads7846_register_types)