Archipelago » qemu

/*

 * MAXIM DS1338 I2C RTC+NVRAM

 *

 * Copyright (c) 2009 CodeSourcery.

 * Written by Paul Brook

 *

 * This code is licensed under the GNU GPL v2.

 *

 * Contributions after 2012-01-13 are licensed under the terms of the

 * GNU GPL, version 2 or (at your option) any later version.

 */

#include "hw/i2c/i2c.h"

/* Size of NVRAM including both the user-accessible area and the

 * secondary register area.

 */

#define NVRAM_SIZE 64

/* Flags definitions */

#define SECONDS_CH 0x80

#define HOURS_12   0x40

#define HOURS_PM   0x20

#define CTRL_OSF   0x20

typedef struct {

    I2CSlave i2c;

    int64_t offset;

    uint8_t wday_offset;

    uint8_t nvram[NVRAM_SIZE];

    int32_t ptr;

    bool addr_byte;

} DS1338State;

static const VMStateDescription vmstate_ds1338 = {

    .name = "ds1338",

    .version_id = 2,

    .minimum_version_id = 1,

    .minimum_version_id_old = 1,

    .fields = (VMStateField[]) {

        VMSTATE_I2C_SLAVE(i2c, DS1338State),

        VMSTATE_INT64(offset, DS1338State),

        VMSTATE_UINT8_V(wday_offset, DS1338State, 2),

        VMSTATE_UINT8_ARRAY(nvram, DS1338State, NVRAM_SIZE),

        VMSTATE_INT32(ptr, DS1338State),

        VMSTATE_BOOL(addr_byte, DS1338State),

        VMSTATE_END_OF_LIST()

    }

};

static void capture_current_time(DS1338State *s)

{

    /* Capture the current time into the secondary registers

     * which will be actually read by the data transfer operation.

     */

    struct tm now;

    qemu_get_timedate(&now, s->offset);

    s->nvram[0] = to_bcd(now.tm_sec);

    s->nvram[1] = to_bcd(now.tm_min);

    if (s->nvram[2] & HOURS_12) {

        int tmp = now.tm_hour;

        if (tmp % 12 == 0) {

            tmp += 12;

        }

        if (tmp <= 12) {

            s->nvram[2] = HOURS_12 | to_bcd(tmp);

        } else {

            s->nvram[2] = HOURS_12 | HOURS_PM | to_bcd(tmp - 12);

        }

    } else {

        s->nvram[2] = to_bcd(now.tm_hour);

    }

    s->nvram[3] = (now.tm_wday + s->wday_offset) % 7 + 1;

    s->nvram[4] = to_bcd(now.tm_mday);

    s->nvram[5] = to_bcd(now.tm_mon + 1);

    s->nvram[6] = to_bcd(now.tm_year - 100);

}

static void inc_regptr(DS1338State *s)

{

    /* The register pointer wraps around after 0x3F; wraparound

     * causes the current time/date to be retransferred into

     * the secondary registers.

     */

    s->ptr = (s->ptr + 1) & (NVRAM_SIZE - 1);

    if (!s->ptr) {

        capture_current_time(s);

    }

}

static void ds1338_event(I2CSlave *i2c, enum i2c_event event)

{

    DS1338State *s = FROM_I2C_SLAVE(DS1338State, i2c);

    switch (event) {

    case I2C_START_RECV:

        /* In h/w, capture happens on any START condition, not just a

         * START_RECV, but there is no need to actually capture on

         * START_SEND, because the guest can't get at that data

         * without going through a START_RECV which would overwrite it.

         */

        capture_current_time(s);

        break;

    case I2C_START_SEND:

        s->addr_byte = true;

        break;

    default:

        break;

    }

}

static int ds1338_recv(I2CSlave *i2c)

{

    DS1338State *s = FROM_I2C_SLAVE(DS1338State, i2c);

    uint8_t res;

    res  = s->nvram[s->ptr];

    inc_regptr(s);

    return res;

}

static int ds1338_send(I2CSlave *i2c, uint8_t data)

{

    DS1338State *s = FROM_I2C_SLAVE(DS1338State, i2c);

    if (s->addr_byte) {

        s->ptr = data & (NVRAM_SIZE - 1);

        s->addr_byte = false;

        return 0;

    }

    if (s->ptr < 7) {

        /* Time register. */

        struct tm now;

        qemu_get_timedate(&now, s->offset);

        switch(s->ptr) {

        case 0:

            /* TODO: Implement CH (stop) bit.  */

            now.tm_sec = from_bcd(data & 0x7f);

            break;

        case 1:

            now.tm_min = from_bcd(data & 0x7f);

            break;

        case 2:

            if (data & HOURS_12) {

                int tmp = from_bcd(data & (HOURS_PM - 1));

                if (data & HOURS_PM) {

                    tmp += 12;

                }

                if (tmp % 12 == 0) {

                    tmp -= 12;

                }

                now.tm_hour = tmp;

            } else {

                now.tm_hour = from_bcd(data & (HOURS_12 - 1));

            }

            break;

        case 3:

            {

                /* The day field is supposed to contain a value in

                   the range 1-7. Otherwise behavior is undefined.

                 */

                int user_wday = (data & 7) - 1;

                s->wday_offset = (user_wday - now.tm_wday + 7) % 7;

            }

            break;

        case 4:

            now.tm_mday = from_bcd(data & 0x3f);

            break;

        case 5:

            now.tm_mon = from_bcd(data & 0x1f) - 1;

            break;

        case 6:

            now.tm_year = from_bcd(data) + 100;

            break;

        }

        s->offset = qemu_timedate_diff(&now);

    } else if (s->ptr == 7) {

        /* Control register. */

        /* Ensure bits 2, 3 and 6 will read back as zero. */

        data &= 0xB3;

        /* Attempting to write the OSF flag to logic 1 leaves the

           value unchanged. */

        data = (data & ~CTRL_OSF) | (data & s->nvram[s->ptr] & CTRL_OSF);

        s->nvram[s->ptr] = data;

    } else {

        s->nvram[s->ptr] = data;

    }

    inc_regptr(s);

    return 0;

}

static int ds1338_init(I2CSlave *i2c)

{

    return 0;

}

static void ds1338_reset(DeviceState *dev)

{

    DS1338State *s = FROM_I2C_SLAVE(DS1338State, I2C_SLAVE(dev));

    /* The clock is running and synchronized with the host */

    s->offset = 0;

    s->wday_offset = 0;

    memset(s->nvram, 0, NVRAM_SIZE);

    s->ptr = 0;

    s->addr_byte = false;

}

static void ds1338_class_init(ObjectClass *klass, void *data)

{

    DeviceClass *dc = DEVICE_CLASS(klass);

    I2CSlaveClass *k = I2C_SLAVE_CLASS(klass);

    k->init = ds1338_init;

    k->event = ds1338_event;

    k->recv = ds1338_recv;

    k->send = ds1338_send;

    dc->reset = ds1338_reset;

    dc->vmsd = &vmstate_ds1338;

}

static const TypeInfo ds1338_info = {

    .name          = "ds1338",

    .parent        = TYPE_I2C_SLAVE,

    .instance_size = sizeof(DS1338State),

    .class_init    = ds1338_class_init,

};

static void ds1338_register_types(void)

{

    type_register_static(&ds1338_info);

}

type_init(ds1338_register_types)