rtc-rx8581.c

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/*
 * An I2C driver for the Epson RX8581 RTC
 *
 * Author: Martyn Welch <[email protected]>
 * Copyright 2008 GE Intelligent Platforms Embedded Systems, Inc.
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License version 2 as
 * published by the Free Software Foundation.
 *
 * Based on: rtc-pcf8563.c (An I2C driver for the Philips PCF8563 RTC)
 * Copyright 2005-06 Tower Technologies
 */

#include <linux/module.h>
#include <linux/i2c.h>
#include <linux/bcd.h>
#include <linux/rtc.h>
#include <linux/log2.h>

#define DRV_VERSION "0.1"

#define RX8581_REG_SC       0x00 /* Second in BCD */
#define RX8581_REG_MN       0x01 /* Minute in BCD */
#define RX8581_REG_HR       0x02 /* Hour in BCD */
#define RX8581_REG_DW       0x03 /* Day of Week */
#define RX8581_REG_DM       0x04 /* Day of Month in BCD */
#define RX8581_REG_MO       0x05 /* Month in BCD */
#define RX8581_REG_YR       0x06 /* Year in BCD */
#define RX8581_REG_RAM      0x07 /* RAM */
#define RX8581_REG_AMN      0x08 /* Alarm Min in BCD*/
#define RX8581_REG_AHR      0x09 /* Alarm Hour in BCD */
#define RX8581_REG_ADM      0x0A
#define RX8581_REG_ADW      0x0A
#define RX8581_REG_TMR0     0x0B
#define RX8581_REG_TMR1     0x0C
#define RX8581_REG_EXT      0x0D /* Extension Register */
#define RX8581_REG_FLAG     0x0E /* Flag Register */
#define RX8581_REG_CTRL     0x0F /* Control Register */


/* Flag Register bit definitions */
#define RX8581_FLAG_UF      0x20 /* Update */
#define RX8581_FLAG_TF      0x10 /* Timer */
#define RX8581_FLAG_AF      0x08 /* Alarm */
#define RX8581_FLAG_VLF     0x02 /* Voltage Low */

/* Control Register bit definitions */
#define RX8581_CTRL_UIE     0x20 /* Update Interrupt Enable */
#define RX8581_CTRL_TIE     0x10 /* Timer Interrupt Enable */
#define RX8581_CTRL_AIE     0x08 /* Alarm Interrupt Enable */
#define RX8581_CTRL_STOP    0x02 /* STOP bit */
#define RX8581_CTRL_RESET   0x01 /* RESET bit */

static struct i2c_driver rx8581_driver;

/*
 * In the routines that deal directly with the rx8581 hardware, we use
 * rtc_time -- month 0-11, hour 0-23, yr = calendar year-epoch.
 */
static int rx8581_get_datetime(struct i2c_client *client, struct rtc_time *tm)
{
    unsigned char date[7];
    int data, err;

    /* First we ensure that the "update flag" is not set, we read the
     * time and date then re-read the "update flag". If the update flag
     * has been set, we know that the time has changed during the read so
     * we repeat the whole process again.
     */
    data = i2c_smbus_read_byte_data(client, RX8581_REG_FLAG);
    if (data < 0) {
        dev_err(&client->dev, "Unable to read device flags\n");
        return -EIO;
    }

    do {
        /* If update flag set, clear it */
        if (data & RX8581_FLAG_UF) {
            err = i2c_smbus_write_byte_data(client,
                RX8581_REG_FLAG, (data & ~RX8581_FLAG_UF));
            if (err != 0) {
                dev_err(&client->dev, "Unable to write device "
                    "flags\n");
                return -EIO;
            }
        }

        /* Now read time and date */
        err = i2c_smbus_read_i2c_block_data(client, RX8581_REG_SC,
            7, date);
        if (err < 0) {
            dev_err(&client->dev, "Unable to read date\n");
            return -EIO;
        }

        /* Check flag register */
        data = i2c_smbus_read_byte_data(client, RX8581_REG_FLAG);
        if (data < 0) {
            dev_err(&client->dev, "Unable to read device flags\n");
            return -EIO;
        }
    } while (data & RX8581_FLAG_UF);

    if (data & RX8581_FLAG_VLF)
        dev_info(&client->dev,
            "low voltage detected, date/time is not reliable.\n");

    dev_dbg(&client->dev,
        "%s: raw data is sec=%02x, min=%02x, hr=%02x, "
        "wday=%02x, mday=%02x, mon=%02x, year=%02x\n",
        __func__,
        date[0], date[1], date[2], date[3], date[4], date[5], date[6]);

    tm->tm_sec = bcd2bin(date[RX8581_REG_SC] & 0x7F);
    tm->tm_min = bcd2bin(date[RX8581_REG_MN] & 0x7F);
    tm->tm_hour = bcd2bin(date[RX8581_REG_HR] & 0x3F); /* rtc hr 0-23 */
    tm->tm_wday = ilog2(date[RX8581_REG_DW] & 0x7F);
    tm->tm_mday = bcd2bin(date[RX8581_REG_DM] & 0x3F);
    tm->tm_mon = bcd2bin(date[RX8581_REG_MO] & 0x1F) - 1; /* rtc mn 1-12 */
    tm->tm_year = bcd2bin(date[RX8581_REG_YR]);
    if (tm->tm_year < 70)
        tm->tm_year += 100; /* assume we are in 1970...2069 */


    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);

    err = rtc_valid_tm(tm);
    if (err < 0)
        dev_err(&client->dev, "retrieved date/time is not valid.\n");

    return err;
}

static int rx8581_set_datetime(struct i2c_client *client, struct rtc_time *tm)
{
    int data, err;
    unsigned char buf[7];

    dev_dbg(&client->dev, "%s: 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);

    /* hours, minutes and seconds */
    buf[RX8581_REG_SC] = bin2bcd(tm->tm_sec);
    buf[RX8581_REG_MN] = bin2bcd(tm->tm_min);
    buf[RX8581_REG_HR] = bin2bcd(tm->tm_hour);

    buf[RX8581_REG_DM] = bin2bcd(tm->tm_mday);

    /* month, 1 - 12 */
    buf[RX8581_REG_MO] = bin2bcd(tm->tm_mon + 1);

    /* year and century */
    buf[RX8581_REG_YR] = bin2bcd(tm->tm_year % 100);
    buf[RX8581_REG_DW] = (0x1 << tm->tm_wday);

    /* Stop the clock */
    data = i2c_smbus_read_byte_data(client, RX8581_REG_CTRL);
    if (data < 0) {
        dev_err(&client->dev, "Unable to read control register\n");
        return -EIO;
    }

    err = i2c_smbus_write_byte_data(client, RX8581_REG_CTRL,
        (data | RX8581_CTRL_STOP));
    if (err < 0) {
        dev_err(&client->dev, "Unable to write control register\n");
        return -EIO;
    }

    /* write register's data */
    err = i2c_smbus_write_i2c_block_data(client, RX8581_REG_SC, 7, buf);
    if (err < 0) {
        dev_err(&client->dev, "Unable to write to date registers\n");
        return -EIO;
    }

    /* get VLF and clear it */
    data = i2c_smbus_read_byte_data(client, RX8581_REG_FLAG);
    if (data < 0) {
        dev_err(&client->dev, "Unable to read flag register\n");
        return -EIO;
    }

    err = i2c_smbus_write_byte_data(client, RX8581_REG_FLAG,
        (data & ~(RX8581_FLAG_VLF)));
    if (err != 0) {
        dev_err(&client->dev, "Unable to write flag register\n");
        return -EIO;
    }

    /* Restart the clock */
    data = i2c_smbus_read_byte_data(client, RX8581_REG_CTRL);
    if (data < 0) {
        dev_err(&client->dev, "Unable to read control register\n");
        return -EIO;
    }

    err = i2c_smbus_write_byte_data(client, RX8581_REG_CTRL,
        (data & ~(RX8581_CTRL_STOP)));
    if (err != 0) {
        dev_err(&client->dev, "Unable to write control register\n");
        return -EIO;
    }

    return 0;
}

static int rx8581_rtc_read_time(struct device *dev, struct rtc_time *tm)
{
    return rx8581_get_datetime(to_i2c_client(dev), tm);
}

static int rx8581_rtc_set_time(struct device *dev, struct rtc_time *tm)
{
    return rx8581_set_datetime(to_i2c_client(dev), tm);
}

static const struct rtc_class_ops rx8581_rtc_ops = {
    .read_time  = rx8581_rtc_read_time,
    .set_time   = rx8581_rtc_set_time,
};

static int __devinit rx8581_probe(struct i2c_client *client,
                const struct i2c_device_id *id)
{
    struct rtc_device *rtc;

    dev_dbg(&client->dev, "%s\n", __func__);

    if (!i2c_check_functionality(client->adapter, I2C_FUNC_I2C))
        return -ENODEV;

    dev_info(&client->dev, "chip found, driver version " DRV_VERSION "\n");

    rtc = rtc_device_register(rx8581_driver.driver.name,
                &client->dev, &rx8581_rtc_ops, THIS_MODULE);

    if (IS_ERR(rtc))
        return PTR_ERR(rtc);

    i2c_set_clientdata(client, rtc);

    return 0;
}

static int __devexit rx8581_remove(struct i2c_client *client)
{
    struct rtc_device *rtc = i2c_get_clientdata(client);

    rtc_device_unregister(rtc);

    return 0;
}

static const struct i2c_device_id rx8581_id[] = {
    { "rx8581", 0 },
    { }
};
MODULE_DEVICE_TABLE(i2c, rx8581_id);

static struct i2c_driver rx8581_driver = {
    .driver     = {
        .name   = "rtc-rx8581",
        .owner  = THIS_MODULE,
    },
    .probe      = rx8581_probe,
    .remove     = __devexit_p(rx8581_remove),
    .id_table   = rx8581_id,
};

module_i2c_driver(rx8581_driver);

MODULE_AUTHOR("Martyn Welch <[email protected]>");
MODULE_DESCRIPTION("Epson RX-8581 RTC driver");
MODULE_LICENSE("GPL");
MODULE_VERSION(DRV_VERSION);