summaryrefslogtreecommitdiff
path: root/hw/ads7846.c
blob: 2f891b125116d4119d3b4d08698fdaa28a30b28a (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
/*
 * TI ADS7846 chip emulation.
 *
 * Copyright (c) 2006 Openedhand Ltd.
 * Written by Andrzej Zaborowski <balrog@zabor.org>
 *
 * This code is licensed under the GNU GPL v2.
 */

#include <vl.h>

struct ads7846_state_s {
    qemu_irq interrupt;

    int input[8];
    int pressure;
    int noise;

    int cycle;
    int output;
};

/* Control-byte bitfields */
#define CB_PD0		(1 << 0)
#define CB_PD1		(1 << 1)
#define CB_SER		(1 << 2)
#define CB_MODE		(1 << 3)
#define CB_A0		(1 << 4)
#define CB_A1		(1 << 5)
#define CB_A2		(1 << 6)
#define CB_START	(1 << 7)

#define X_AXIS_DMAX	3470
#define X_AXIS_MIN	290
#define Y_AXIS_DMAX	3450
#define Y_AXIS_MIN	200

#define ADS_VBAT	2000
#define ADS_VAUX	2000
#define ADS_TEMP0	2000
#define ADS_TEMP1	3000
#define ADS_XPOS(x, y)	(X_AXIS_MIN + ((X_AXIS_DMAX * (x)) >> 15))
#define ADS_YPOS(x, y)	(Y_AXIS_MIN + ((Y_AXIS_DMAX * (y)) >> 15))
#define ADS_Z1POS(x, y)	600
#define ADS_Z2POS(x, y)	(600 + 6000 / ADS_XPOS(x, y))

static void ads7846_int_update(struct ads7846_state_s *s)
{
    if (s->interrupt)
        qemu_set_irq(s->interrupt, s->pressure == 0);
}

uint32_t ads7846_read(void *opaque)
{
    struct ads7846_state_s *s = (struct ads7846_state_s *) opaque;

    return s->output;
}

void ads7846_write(void *opaque, uint32_t value)
{
    struct ads7846_state_s *s = (struct ads7846_state_s *) opaque;

    switch (s->cycle ++) {
    case 0:
        if (!(value & CB_START)) {
            s->cycle = 0;
            break;
        }

        s->output = s->input[(value >> 4) & 7];

        /* Imitate the ADC noise, some drivers expect this.  */
        s->noise = (s->noise + 3) & 7;
        switch ((value >> 4) & 7) {
        case 1: s->output += s->noise ^ 2; break;
        case 3: s->output += s->noise ^ 0; break;
        case 4: s->output += s->noise ^ 7; break;
        case 5: s->output += s->noise ^ 5; break;
        }

        if (value & CB_MODE)
            s->output >>= 4;	/* 8 bits instead of 12 */

        break;
    case 1:
        s->cycle = 0;
        break;
    }
}

static void ads7846_ts_event(void *opaque,
                int x, int y, int z, int buttons_state)
{
    struct ads7846_state_s *s = opaque;

    if (buttons_state) {
        x = 0x7fff - x;
        s->input[1] = ADS_XPOS(x, y);
        s->input[3] = ADS_Z1POS(x, y);
        s->input[4] = ADS_Z2POS(x, y);
        s->input[5] = ADS_YPOS(x, y);
    }

    if (s->pressure == !buttons_state) {
        s->pressure = !!buttons_state;

        ads7846_int_update(s);
    }
}

static void ads7846_save(QEMUFile *f, void *opaque)
{
    struct ads7846_state_s *s = (struct ads7846_state_s *) opaque;
    int i;

    for (i = 0; i < 8; i ++)
        qemu_put_be32(f, s->input[i]);
    qemu_put_be32(f, s->noise);
    qemu_put_be32(f, s->cycle);
    qemu_put_be32(f, s->output);
}

static int ads7846_load(QEMUFile *f, void *opaque, int version_id)
{
    struct ads7846_state_s *s = (struct ads7846_state_s *) opaque;
    int i;

    for (i = 0; i < 8; i ++)
        s->input[i] = qemu_get_be32(f);
    s->noise = qemu_get_be32(f);
    s->cycle = qemu_get_be32(f);
    s->output = qemu_get_be32(f);

    s->pressure = 0;
    ads7846_int_update(s);

    return 0;
}

static int ads7846_iid = 0;

struct ads7846_state_s *ads7846_init(qemu_irq penirq)
{
    struct ads7846_state_s *s;
    s = (struct ads7846_state_s *)
            qemu_mallocz(sizeof(struct ads7846_state_s));
    memset(s, 0, sizeof(struct ads7846_state_s));

    s->interrupt = penirq;

    s->input[0] = ADS_TEMP0;	/* TEMP0 */
    s->input[2] = ADS_VBAT;	/* VBAT */
    s->input[6] = ADS_VAUX;	/* VAUX */
    s->input[7] = ADS_TEMP1;	/* TEMP1 */

    /* We want absolute coordinates */
    qemu_add_mouse_event_handler(ads7846_ts_event, s, 1,
                    "QEMU ADS7846-driven Touchscreen");

    ads7846_int_update(s);

    register_savevm("ads7846", ads7846_iid ++, 0,
                    ads7846_save, ads7846_load, s);

    return s;
}