2 * TI ADS7846 chip emulation.
4 * Copyright (c) 2006 Openedhand Ltd.
5 * Written by Andrzej Zaborowski <balrog@zabor.org>
7 * This code is licensed under the GNU GPL v2.
12 struct ads7846_state_s {
23 /* Control-byte bitfields */
24 #define CB_PD0 (1 << 0)
25 #define CB_PD1 (1 << 1)
26 #define CB_SER (1 << 2)
27 #define CB_MODE (1 << 3)
28 #define CB_A0 (1 << 4)
29 #define CB_A1 (1 << 5)
30 #define CB_A2 (1 << 6)
31 #define CB_START (1 << 7)
33 #define X_AXIS_DMAX 3680
34 #define X_AXIS_MIN 150
35 #define Y_AXIS_DMAX 3640
36 #define Y_AXIS_MIN 190
40 #define ADS_TEMP0 2000
41 #define ADS_TEMP1 3000
42 #define ADS_XPOS(x, y) (X_AXIS_MIN + ((X_AXIS_DMAX * (x)) >> 15))
43 #define ADS_YPOS(x, y) (Y_AXIS_MIN + ((Y_AXIS_DMAX * (y)) >> 15))
44 #define ADS_Z1POS(x, y) 600
45 #define ADS_Z2POS(x, y) (600 + 6000 / ADS_XPOS(x, y))
47 static void ads7846_int_update(struct ads7846_state_s *s)
50 qemu_set_irq(s->interrupt, s->pressure == 0);
53 uint32_t ads7846_read(void *opaque)
55 struct ads7846_state_s *s = (struct ads7846_state_s *) opaque;
60 void ads7846_write(void *opaque, uint32_t value)
62 struct ads7846_state_s *s = (struct ads7846_state_s *) opaque;
64 switch (s->cycle ++) {
66 if (!(value & CB_START)) {
71 s->output = s->input[(value >> 4) & 7];
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;
83 s->output >>= 4; /* 8 bits instead of 12 */
92 static void ads7846_ts_event(void *opaque,
93 int x, int y, int z, int buttons_state)
95 struct ads7846_state_s *s = opaque;
98 s->input[1] = ADS_YPOS(x, y);
99 s->input[3] = ADS_Z1POS(x, y);
100 s->input[4] = ADS_Z2POS(x, y);
101 s->input[5] = ADS_XPOS(x, y);
104 if (s->pressure == !buttons_state) {
105 s->pressure = !!buttons_state;
107 ads7846_int_update(s);
111 struct ads7846_state_s *ads7846_init(qemu_irq penirq)
113 struct ads7846_state_s *s;
114 s = (struct ads7846_state_s *)
115 qemu_mallocz(sizeof(struct ads7846_state_s));
116 memset(s, 0, sizeof(struct ads7846_state_s));
118 s->interrupt = penirq;
120 s->input[0] = ADS_TEMP0; /* TEMP0 */
121 s->input[2] = ADS_VBAT; /* VBAT */
122 s->input[6] = ADS_VAUX; /* VAUX */
123 s->input[7] = ADS_TEMP1; /* TEMP1 */
125 /* We want absolute coordinates */
126 qemu_add_mouse_event_handler(ads7846_ts_event, s, 1,
127 "QEMU ADS7846-driven Touchscreen");
129 ads7846_int_update(s);