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