rtc-pcf8563.c

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/*
 * An I2C driver for the Philips PCF8563 RTC
 * Copyright 2005-06 Tower Technologies
 *
 * Author: Alessandro Zummo <[email protected]>
 * Maintainers: http://www.nslu2-linux.org/
 *
 * based on the other drivers in this same directory.
 *
 * http://www.semiconductors.philips.com/acrobat/datasheets/PCF8563-04.pdf
 *
 * 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.
 */

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

#define DRV_VERSION "0.4.3"

#define PCF8563_REG_ST1     0x00 /* status */
#define PCF8563_REG_ST2     0x01

#define PCF8563_REG_SC      0x02 /* datetime */
#define PCF8563_REG_MN      0x03
#define PCF8563_REG_HR      0x04
#define PCF8563_REG_DM      0x05
#define PCF8563_REG_DW      0x06
#define PCF8563_REG_MO      0x07
#define PCF8563_REG_YR      0x08

#define PCF8563_REG_AMN     0x09 /* alarm */
#define PCF8563_REG_AHR     0x0A
#define PCF8563_REG_ADM     0x0B
#define PCF8563_REG_ADW     0x0C

#define PCF8563_REG_CLKO    0x0D /* clock out */
#define PCF8563_REG_TMRC    0x0E /* timer control */
#define PCF8563_REG_TMR     0x0F /* timer */

#define PCF8563_SC_LV       0x80 /* low voltage */
#define PCF8563_MO_C        0x80 /* century */

static struct i2c_driver pcf8563_driver;

struct pcf8563 {
    struct rtc_device *rtc;
    /*
     * The meaning of MO_C bit varies by the chip type.
     * From PCF8563 datasheet: this bit is toggled when the years
     * register overflows from 99 to 00
     *   0 indicates the century is 20xx
     *   1 indicates the century is 19xx
     * From RTC8564 datasheet: this bit indicates change of
     * century. When the year digit data overflows from 99 to 00,
     * this bit is set. By presetting it to 0 while still in the
     * 20th century, it will be set in year 2000, ...
     * There seems no reliable way to know how the system use this
     * bit.  So let's do it heuristically, assuming we are live in
     * 1970...2069.
     */
    int c_polarity; /* 0: MO_C=1 means 19xx, otherwise MO_C=1 means 20xx */
    int voltage_low; /* incicates if a low_voltage was detected */
};

/*
 * In the routines that deal directly with the pcf8563 hardware, we use
 * rtc_time -- month 0-11, hour 0-23, yr = calendar year-epoch.
 */
static int pcf8563_get_datetime(struct i2c_client *client, struct rtc_time *tm)
{
    struct pcf8563 *pcf8563 = i2c_get_clientdata(client);
    unsigned char buf[13] = { PCF8563_REG_ST1 };

    struct i2c_msg msgs[] = {
        {/* setup read ptr */
            .addr = client->addr,
            .len = 1,
            .buf = buf
        },
        {/* read status + date */
            .addr = client->addr,
            .flags = I2C_M_RD,
            .len = 13,
            .buf = buf
        },
    };

    /* read registers */
    if ((i2c_transfer(client->adapter, msgs, 2)) != 2) {
        dev_err(&client->dev, "%s: read error\n", __func__);
        return -EIO;
    }

    if (buf[PCF8563_REG_SC] & PCF8563_SC_LV) {
        pcf8563->voltage_low = 1;
        dev_info(&client->dev,
            "low voltage detected, date/time is not reliable.\n");
    }

    dev_dbg(&client->dev,
        "%s: raw data is st1=%02x, st2=%02x, sec=%02x, min=%02x, hr=%02x, "
        "mday=%02x, wday=%02x, mon=%02x, year=%02x\n",
        __func__,
        buf[0], buf[1], buf[2], buf[3],
        buf[4], buf[5], buf[6], buf[7],
        buf[8]);


    tm->tm_sec = bcd2bin(buf[PCF8563_REG_SC] & 0x7F);
    tm->tm_min = bcd2bin(buf[PCF8563_REG_MN] & 0x7F);
    tm->tm_hour = bcd2bin(buf[PCF8563_REG_HR] & 0x3F); /* rtc hr 0-23 */
    tm->tm_mday = bcd2bin(buf[PCF8563_REG_DM] & 0x3F);
    tm->tm_wday = buf[PCF8563_REG_DW] & 0x07;
    tm->tm_mon = bcd2bin(buf[PCF8563_REG_MO] & 0x1F) - 1; /* rtc mn 1-12 */
    tm->tm_year = bcd2bin(buf[PCF8563_REG_YR]);
    if (tm->tm_year < 70)
        tm->tm_year += 100; /* assume we are in 1970...2069 */
    /* detect the polarity heuristically. see note above. */
    pcf8563->c_polarity = (buf[PCF8563_REG_MO] & PCF8563_MO_C) ?
        (tm->tm_year >= 100) : (tm->tm_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);

    /* the clock can give out invalid datetime, but we cannot return
     * -EINVAL otherwise hwclock will refuse to set the time on bootup.
     */
    if (rtc_valid_tm(tm) < 0)
        dev_err(&client->dev, "retrieved date/time is not valid.\n");

    return 0;
}

static int pcf8563_set_datetime(struct i2c_client *client, struct rtc_time *tm)
{
    struct pcf8563 *pcf8563 = i2c_get_clientdata(client);
    int i, err;
    unsigned char buf[9];

    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[PCF8563_REG_SC] = bin2bcd(tm->tm_sec);
    buf[PCF8563_REG_MN] = bin2bcd(tm->tm_min);
    buf[PCF8563_REG_HR] = bin2bcd(tm->tm_hour);

    buf[PCF8563_REG_DM] = bin2bcd(tm->tm_mday);

    /* month, 1 - 12 */
    buf[PCF8563_REG_MO] = bin2bcd(tm->tm_mon + 1);

    /* year and century */
    buf[PCF8563_REG_YR] = bin2bcd(tm->tm_year % 100);
    if (pcf8563->c_polarity ? (tm->tm_year >= 100) : (tm->tm_year < 100))
        buf[PCF8563_REG_MO] |= PCF8563_MO_C;

    buf[PCF8563_REG_DW] = tm->tm_wday & 0x07;

    /* write register's data */
    for (i = 0; i < 7; i++) {
        unsigned char data[2] = { PCF8563_REG_SC + i,
                        buf[PCF8563_REG_SC + i] };

        err = i2c_master_send(client, data, sizeof(data));
        if (err != sizeof(data)) {
            dev_err(&client->dev,
                "%s: err=%d addr=%02x, data=%02x\n",
                __func__, err, data[0], data[1]);
            return -EIO;
        }
    };

    return 0;
}

#ifdef CONFIG_RTC_INTF_DEV
static int pcf8563_rtc_ioctl(struct device *dev, unsigned int cmd, unsigned long arg)
{
    struct pcf8563 *pcf8563 = i2c_get_clientdata(to_i2c_client(dev));
    struct rtc_time tm;

    switch (cmd) {
    case RTC_VL_READ:
        if (pcf8563->voltage_low)
            dev_info(dev, "low voltage detected, date/time is not reliable.\n");

        if (copy_to_user((void __user *)arg, &pcf8563->voltage_low,
                    sizeof(int)))
            return -EFAULT;
        return 0;
    case RTC_VL_CLR:
        /*
         * Clear the VL bit in the seconds register in case
         * the time has not been set already (which would
         * have cleared it). This does not really matter
         * because of the cached voltage_low value but do it
         * anyway for consistency.
         */
        if (pcf8563_get_datetime(to_i2c_client(dev), &tm))
            pcf8563_set_datetime(to_i2c_client(dev), &tm);

        /* Clear the cached value. */
        pcf8563->voltage_low = 0;

        return 0;
    default:
        return -ENOIOCTLCMD;
    }
}
#else
#define pcf8563_rtc_ioctl NULL
#endif

static int pcf8563_rtc_read_time(struct device *dev, struct rtc_time *tm)
{
    return pcf8563_get_datetime(to_i2c_client(dev), tm);
}

static int pcf8563_rtc_set_time(struct device *dev, struct rtc_time *tm)
{
    return pcf8563_set_datetime(to_i2c_client(dev), tm);
}

static const struct rtc_class_ops pcf8563_rtc_ops = {
    .ioctl      = pcf8563_rtc_ioctl,
    .read_time  = pcf8563_rtc_read_time,
    .set_time   = pcf8563_rtc_set_time,
};

static int pcf8563_probe(struct i2c_client *client,
                const struct i2c_device_id *id)
{
    struct pcf8563 *pcf8563;

    int err = 0;

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

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

    pcf8563 = kzalloc(sizeof(struct pcf8563), GFP_KERNEL);
    if (!pcf8563)
        return -ENOMEM;

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

    i2c_set_clientdata(client, pcf8563);

    pcf8563->rtc = rtc_device_register(pcf8563_driver.driver.name,
                &client->dev, &pcf8563_rtc_ops, THIS_MODULE);

    if (IS_ERR(pcf8563->rtc)) {
        err = PTR_ERR(pcf8563->rtc);
        goto exit_kfree;
    }

    return 0;

exit_kfree:
    kfree(pcf8563);

    return err;
}

static int pcf8563_remove(struct i2c_client *client)
{
    struct pcf8563 *pcf8563 = i2c_get_clientdata(client);

    if (pcf8563->rtc)
        rtc_device_unregister(pcf8563->rtc);

    kfree(pcf8563);

    return 0;
}

static const struct i2c_device_id pcf8563_id[] = {
    { "pcf8563", 0 },
    { "rtc8564", 0 },
    { }
};
MODULE_DEVICE_TABLE(i2c, pcf8563_id);

#ifdef CONFIG_OF
static const struct of_device_id pcf8563_of_match[] __devinitconst = {
    { .compatible = "nxp,pcf8563" },
    {}
};
MODULE_DEVICE_TABLE(of, pcf8563_of_match);
#endif

static struct i2c_driver pcf8563_driver = {
    .driver     = {
        .name   = "rtc-pcf8563",
        .owner  = THIS_MODULE,
        .of_match_table = of_match_ptr(pcf8563_of_match),
    },
    .probe      = pcf8563_probe,
    .remove     = pcf8563_remove,
    .id_table   = pcf8563_id,
};

module_i2c_driver(pcf8563_driver);

MODULE_AUTHOR("Alessandro Zummo <[email protected]>");
MODULE_DESCRIPTION("Philips PCF8563/Epson RTC8564 RTC driver");
MODULE_LICENSE("GPL");
MODULE_VERSION(DRV_VERSION);