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