/*

 * TI ADS7846 / TSC2046 chip emulation.

 *

 * Copyright (c) 2006 Openedhand Ltd.

 * Written by Andrzej Zaborowski <balrog@zabor.org>

 *

 * This code is licensed under the GNU GPL v2.

 */

#include "hw.h"

#include "devices.h"

#include "console.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;

}

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", -1, 0, ads7846_save, ads7846_load, s);

    return s;

}