rtc-s35390a.c

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/*
 * Seiko Instruments S-35390A RTC Driver
 *
 * Copyright (c) 2007 Byron Bradley
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public License
 * as published by the Free Software Foundation; either version
 * 2 of the License, or (at your option) any later version.
 */

#include <linux/module.h>
#include <linux/rtc.h>
#include <linux/i2c.h>
#include <linux/bitrev.h>
#include <linux/bcd.h>
#include <linux/slab.h>

#define S35390A_CMD_STATUS1 0
#define S35390A_CMD_STATUS2 1
#define S35390A_CMD_TIME1   2
#define S35390A_CMD_TIME2   3
#define S35390A_CMD_INT2_REG1   5

#define S35390A_BYTE_YEAR   0
#define S35390A_BYTE_MONTH  1
#define S35390A_BYTE_DAY    2
#define S35390A_BYTE_WDAY   3
#define S35390A_BYTE_HOURS  4
#define S35390A_BYTE_MINS   5
#define S35390A_BYTE_SECS   6

#define S35390A_ALRM_BYTE_WDAY  0
#define S35390A_ALRM_BYTE_HOURS 1
#define S35390A_ALRM_BYTE_MINS  2

#define S35390A_FLAG_POC    0x01
#define S35390A_FLAG_BLD    0x02
#define S35390A_FLAG_24H    0x40
#define S35390A_FLAG_RESET  0x80
#define S35390A_FLAG_TEST   0x01

#define S35390A_INT2_MODE_MASK      0xF0

#define S35390A_INT2_MODE_NOINTR    0x00
#define S35390A_INT2_MODE_FREQ      0x10
#define S35390A_INT2_MODE_ALARM     0x40
#define S35390A_INT2_MODE_PMIN_EDG  0x20

static const struct i2c_device_id s35390a_id[] = {
    { "s35390a", 0 },
    { }
};
MODULE_DEVICE_TABLE(i2c, s35390a_id);

struct s35390a {
    struct i2c_client *client[8];
    struct rtc_device *rtc;
    int twentyfourhour;
};

static int s35390a_set_reg(struct s35390a *s35390a, int reg, char *buf, int len)
{
    struct i2c_client *client = s35390a->client[reg];
    struct i2c_msg msg[] = {
        {
            .addr = client->addr,
            .len = len,
            .buf = buf
        },
    };

    if ((i2c_transfer(client->adapter, msg, 1)) != 1)
        return -EIO;

    return 0;
}

static int s35390a_get_reg(struct s35390a *s35390a, int reg, char *buf, int len)
{
    struct i2c_client *client = s35390a->client[reg];
    struct i2c_msg msg[] = {
        {
            .addr = client->addr,
            .flags = I2C_M_RD,
            .len = len,
            .buf = buf
        },
    };

    if ((i2c_transfer(client->adapter, msg, 1)) != 1)
        return -EIO;

    return 0;
}

static int s35390a_reset(struct s35390a *s35390a)
{
    char buf[1];

    if (s35390a_get_reg(s35390a, S35390A_CMD_STATUS1, buf, sizeof(buf)) < 0)
        return -EIO;

    if (!(buf[0] & (S35390A_FLAG_POC | S35390A_FLAG_BLD)))
        return 0;

    buf[0] |= (S35390A_FLAG_RESET | S35390A_FLAG_24H);
    buf[0] &= 0xf0;
    return s35390a_set_reg(s35390a, S35390A_CMD_STATUS1, buf, sizeof(buf));
}

static int s35390a_disable_test_mode(struct s35390a *s35390a)
{
    char buf[1];

    if (s35390a_get_reg(s35390a, S35390A_CMD_STATUS2, buf, sizeof(buf)) < 0)
        return -EIO;

    if (!(buf[0] & S35390A_FLAG_TEST))
        return 0;

    buf[0] &= ~S35390A_FLAG_TEST;
    return s35390a_set_reg(s35390a, S35390A_CMD_STATUS2, buf, sizeof(buf));
}

static char s35390a_hr2reg(struct s35390a *s35390a, int hour)
{
    if (s35390a->twentyfourhour)
        return bin2bcd(hour);

    if (hour < 12)
        return bin2bcd(hour);

    return 0x40 | bin2bcd(hour - 12);
}

static int s35390a_reg2hr(struct s35390a *s35390a, char reg)
{
    unsigned hour;

    if (s35390a->twentyfourhour)
        return bcd2bin(reg & 0x3f);

    hour = bcd2bin(reg & 0x3f);
    if (reg & 0x40)
        hour += 12;

    return hour;
}

static int s35390a_set_datetime(struct i2c_client *client, struct rtc_time *tm)
{
    struct s35390a  *s35390a = i2c_get_clientdata(client);
    int i, err;
    char buf[7];

    dev_dbg(&client->dev, "%s: tm is secs=%d, mins=%d, hours=%d mday=%d, "
        "mon=%d, year=%d, wday=%d\n", __func__, tm->tm_sec,
        tm->tm_min, tm->tm_hour, tm->tm_mday, tm->tm_mon, tm->tm_year,
        tm->tm_wday);

    buf[S35390A_BYTE_YEAR] = bin2bcd(tm->tm_year - 100);
    buf[S35390A_BYTE_MONTH] = bin2bcd(tm->tm_mon + 1);
    buf[S35390A_BYTE_DAY] = bin2bcd(tm->tm_mday);
    buf[S35390A_BYTE_WDAY] = bin2bcd(tm->tm_wday);
    buf[S35390A_BYTE_HOURS] = s35390a_hr2reg(s35390a, tm->tm_hour);
    buf[S35390A_BYTE_MINS] = bin2bcd(tm->tm_min);
    buf[S35390A_BYTE_SECS] = bin2bcd(tm->tm_sec);

    /* This chip expects the bits of each byte to be in reverse order */
    for (i = 0; i < 7; ++i)
        buf[i] = bitrev8(buf[i]);

    err = s35390a_set_reg(s35390a, S35390A_CMD_TIME1, buf, sizeof(buf));

    return err;
}

static int s35390a_get_datetime(struct i2c_client *client, struct rtc_time *tm)
{
    struct s35390a *s35390a = i2c_get_clientdata(client);
    char buf[7];
    int i, err;

    err = s35390a_get_reg(s35390a, S35390A_CMD_TIME1, buf, sizeof(buf));
    if (err < 0)
        return err;

    /* This chip returns the bits of each byte in reverse order */
    for (i = 0; i < 7; ++i)
        buf[i] = bitrev8(buf[i]);

    tm->tm_sec = bcd2bin(buf[S35390A_BYTE_SECS]);
    tm->tm_min = bcd2bin(buf[S35390A_BYTE_MINS]);
    tm->tm_hour = s35390a_reg2hr(s35390a, buf[S35390A_BYTE_HOURS]);
    tm->tm_wday = bcd2bin(buf[S35390A_BYTE_WDAY]);
    tm->tm_mday = bcd2bin(buf[S35390A_BYTE_DAY]);
    tm->tm_mon = bcd2bin(buf[S35390A_BYTE_MONTH]) - 1;
    tm->tm_year = bcd2bin(buf[S35390A_BYTE_YEAR]) + 100;

    dev_dbg(&client->dev, "%s: tm is secs=%d, mins=%d, hours=%d, mday=%d, "
        "mon=%d, year=%d, wday=%d\n", __func__, tm->tm_sec,
        tm->tm_min, tm->tm_hour, tm->tm_mday, tm->tm_mon, tm->tm_year,
        tm->tm_wday);

    return rtc_valid_tm(tm);
}

static int s35390a_set_alarm(struct i2c_client *client, struct rtc_wkalrm *alm)
{
    struct s35390a *s35390a = i2c_get_clientdata(client);
    char buf[3], sts = 0;
    int err, i;

    dev_dbg(&client->dev, "%s: alm is secs=%d, mins=%d, hours=%d mday=%d, "\
        "mon=%d, year=%d, wday=%d\n", __func__, alm->time.tm_sec,
        alm->time.tm_min, alm->time.tm_hour, alm->time.tm_mday,
        alm->time.tm_mon, alm->time.tm_year, alm->time.tm_wday);

    /* disable interrupt */
    err = s35390a_set_reg(s35390a, S35390A_CMD_STATUS2, &sts, sizeof(sts));
    if (err < 0)
        return err;

    /* clear pending interrupt, if any */
    err = s35390a_get_reg(s35390a, S35390A_CMD_STATUS1, &sts, sizeof(sts));
    if (err < 0)
        return err;

    if (alm->enabled)
        sts = S35390A_INT2_MODE_ALARM;
    else
        sts = S35390A_INT2_MODE_NOINTR;

    /* This chip expects the bits of each byte to be in reverse order */
    sts = bitrev8(sts);

    /* set interupt mode*/
    err = s35390a_set_reg(s35390a, S35390A_CMD_STATUS2, &sts, sizeof(sts));
    if (err < 0)
        return err;

    if (alm->time.tm_wday != -1)
        buf[S35390A_ALRM_BYTE_WDAY] = bin2bcd(alm->time.tm_wday) | 0x80;

    buf[S35390A_ALRM_BYTE_HOURS] = s35390a_hr2reg(s35390a,
            alm->time.tm_hour) | 0x80;
    buf[S35390A_ALRM_BYTE_MINS] = bin2bcd(alm->time.tm_min) | 0x80;

    if (alm->time.tm_hour >= 12)
        buf[S35390A_ALRM_BYTE_HOURS] |= 0x40;

    for (i = 0; i < 3; ++i)
        buf[i] = bitrev8(buf[i]);

    err = s35390a_set_reg(s35390a, S35390A_CMD_INT2_REG1, buf,
                                sizeof(buf));

    return err;
}

static int s35390a_read_alarm(struct i2c_client *client, struct rtc_wkalrm *alm)
{
    struct s35390a *s35390a = i2c_get_clientdata(client);
    char buf[3], sts;
    int i, err;

    err = s35390a_get_reg(s35390a, S35390A_CMD_STATUS2, &sts, sizeof(sts));
    if (err < 0)
        return err;

    if (bitrev8(sts) != S35390A_INT2_MODE_ALARM)
        return -EINVAL;

    err = s35390a_get_reg(s35390a, S35390A_CMD_INT2_REG1, buf, sizeof(buf));
    if (err < 0)
        return err;

    /* This chip returns the bits of each byte in reverse order */
    for (i = 0; i < 3; ++i) {
        buf[i] = bitrev8(buf[i]);
        buf[i] &= ~0x80;
    }

    alm->time.tm_wday = bcd2bin(buf[S35390A_ALRM_BYTE_WDAY]);
    alm->time.tm_hour = s35390a_reg2hr(s35390a,
                        buf[S35390A_ALRM_BYTE_HOURS]);
    alm->time.tm_min = bcd2bin(buf[S35390A_ALRM_BYTE_MINS]);

    dev_dbg(&client->dev, "%s: alm is mins=%d, hours=%d, wday=%d\n",
            __func__, alm->time.tm_min, alm->time.tm_hour,
            alm->time.tm_wday);

    return 0;
}

static int s35390a_rtc_read_alarm(struct device *dev, struct rtc_wkalrm *alm)
{
    return s35390a_read_alarm(to_i2c_client(dev), alm);
}

static int s35390a_rtc_set_alarm(struct device *dev, struct rtc_wkalrm *alm)
{
    return s35390a_set_alarm(to_i2c_client(dev), alm);
}

static int s35390a_rtc_read_time(struct device *dev, struct rtc_time *tm)
{
    return s35390a_get_datetime(to_i2c_client(dev), tm);
}

static int s35390a_rtc_set_time(struct device *dev, struct rtc_time *tm)
{
    return s35390a_set_datetime(to_i2c_client(dev), tm);
}

static const struct rtc_class_ops s35390a_rtc_ops = {
    .read_time  = s35390a_rtc_read_time,
    .set_time   = s35390a_rtc_set_time,
    .set_alarm  = s35390a_rtc_set_alarm,
    .read_alarm = s35390a_rtc_read_alarm,

};

static struct i2c_driver s35390a_driver;

static int s35390a_probe(struct i2c_client *client,
             const struct i2c_device_id *id)
{
    int err;
    unsigned int i;
    struct s35390a *s35390a;
    struct rtc_time tm;
    char buf[1];

    if (!i2c_check_functionality(client->adapter, I2C_FUNC_I2C)) {
        err = -ENODEV;
        goto exit;
    }

    s35390a = kzalloc(sizeof(struct s35390a), GFP_KERNEL);
    if (!s35390a) {
        err = -ENOMEM;
        goto exit;
    }

    s35390a->client[0] = client;
    i2c_set_clientdata(client, s35390a);

    /* This chip uses multiple addresses, use dummy devices for them */
    for (i = 1; i < 8; ++i) {
        s35390a->client[i] = i2c_new_dummy(client->adapter,
                    client->addr + i);
        if (!s35390a->client[i]) {
            dev_err(&client->dev, "Address %02x unavailable\n",
                        client->addr + i);
            err = -EBUSY;
            goto exit_dummy;
        }
    }

    err = s35390a_reset(s35390a);
    if (err < 0) {
        dev_err(&client->dev, "error resetting chip\n");
        goto exit_dummy;
    }

    err = s35390a_disable_test_mode(s35390a);
    if (err < 0) {
        dev_err(&client->dev, "error disabling test mode\n");
        goto exit_dummy;
    }

    err = s35390a_get_reg(s35390a, S35390A_CMD_STATUS1, buf, sizeof(buf));
    if (err < 0) {
        dev_err(&client->dev, "error checking 12/24 hour mode\n");
        goto exit_dummy;
    }
    if (buf[0] & S35390A_FLAG_24H)
        s35390a->twentyfourhour = 1;
    else
        s35390a->twentyfourhour = 0;

    if (s35390a_get_datetime(client, &tm) < 0)
        dev_warn(&client->dev, "clock needs to be set\n");

    device_set_wakeup_capable(&client->dev, 1);

    s35390a->rtc = rtc_device_register(s35390a_driver.driver.name,
                &client->dev, &s35390a_rtc_ops, THIS_MODULE);

    if (IS_ERR(s35390a->rtc)) {
        err = PTR_ERR(s35390a->rtc);
        goto exit_dummy;
    }
    return 0;

exit_dummy:
    for (i = 1; i < 8; ++i)
        if (s35390a->client[i])
            i2c_unregister_device(s35390a->client[i]);
    kfree(s35390a);

exit:
    return err;
}

static int s35390a_remove(struct i2c_client *client)
{
    unsigned int i;

    struct s35390a *s35390a = i2c_get_clientdata(client);
    for (i = 1; i < 8; ++i)
        if (s35390a->client[i])
            i2c_unregister_device(s35390a->client[i]);

    rtc_device_unregister(s35390a->rtc);
    kfree(s35390a);

    return 0;
}

static struct i2c_driver s35390a_driver = {
    .driver     = {
        .name   = "rtc-s35390a",
    },
    .probe      = s35390a_probe,
    .remove     = s35390a_remove,
    .id_table   = s35390a_id,
};

module_i2c_driver(s35390a_driver);

MODULE_AUTHOR("Byron Bradley <[email protected]>");
MODULE_DESCRIPTION("S35390A RTC driver");
MODULE_LICENSE("GPL");