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/*
* 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 3680
#define X_AXIS_MIN 150
#define Y_AXIS_DMAX 3640
#define Y_AXIS_MIN 190
#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) {
s->input[1] = ADS_YPOS(x, y);
s->input[3] = ADS_Z1POS(x, y);
s->input[4] = ADS_Z2POS(x, y);
s->input[5] = ADS_XPOS(x, y);
}
if (s->pressure == !buttons_state) {
s->pressure = !!buttons_state;
ads7846_int_update(s);
}
}
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);
return s;
}
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