rtc-x1205.c

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/*
 * An i2c driver for the Xicor/Intersil X1205 RTC
 * Copyright 2004 Karen Spearel
 * Copyright 2005 Alessandro Zummo
 *
 * please send all reports to:
 *  Karen Spearel <kas111 at gmail dot com>
 *  Alessandro Zummo <[email protected]>
 *
 * based on a lot of other RTC drivers.
 *
 * Information and datasheet:
 * http://www.intersil.com/cda/deviceinfo/0,1477,X1205,00.html
 *
 * 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/delay.h>
#include <linux/module.h>

#define DRV_VERSION "1.0.8"

/* offsets into CCR area */

#define CCR_SEC         0
#define CCR_MIN         1
#define CCR_HOUR        2
#define CCR_MDAY        3
#define CCR_MONTH       4
#define CCR_YEAR        5
#define CCR_WDAY        6
#define CCR_Y2K         7

#define X1205_REG_SR        0x3F    /* status register */
#define X1205_REG_Y2K       0x37
#define X1205_REG_DW        0x36
#define X1205_REG_YR        0x35
#define X1205_REG_MO        0x34
#define X1205_REG_DT        0x33
#define X1205_REG_HR        0x32
#define X1205_REG_MN        0x31
#define X1205_REG_SC        0x30
#define X1205_REG_DTR       0x13
#define X1205_REG_ATR       0x12
#define X1205_REG_INT       0x11
#define X1205_REG_0     0x10
#define X1205_REG_Y2K1      0x0F
#define X1205_REG_DWA1      0x0E
#define X1205_REG_YRA1      0x0D
#define X1205_REG_MOA1      0x0C
#define X1205_REG_DTA1      0x0B
#define X1205_REG_HRA1      0x0A
#define X1205_REG_MNA1      0x09
#define X1205_REG_SCA1      0x08
#define X1205_REG_Y2K0      0x07
#define X1205_REG_DWA0      0x06
#define X1205_REG_YRA0      0x05
#define X1205_REG_MOA0      0x04
#define X1205_REG_DTA0      0x03
#define X1205_REG_HRA0      0x02
#define X1205_REG_MNA0      0x01
#define X1205_REG_SCA0      0x00

#define X1205_CCR_BASE      0x30    /* Base address of CCR */
#define X1205_ALM0_BASE     0x00    /* Base address of ALARM0 */

#define X1205_SR_RTCF       0x01    /* Clock failure */
#define X1205_SR_WEL        0x02    /* Write Enable Latch */
#define X1205_SR_RWEL       0x04    /* Register Write Enable */
#define X1205_SR_AL0        0x20    /* Alarm 0 match */

#define X1205_DTR_DTR0      0x01
#define X1205_DTR_DTR1      0x02
#define X1205_DTR_DTR2      0x04

#define X1205_HR_MIL        0x80    /* Set in ccr.hour for 24 hr mode */

#define X1205_INT_AL0E      0x20    /* Alarm 0 enable */

static struct i2c_driver x1205_driver;

/*
 * In the routines that deal directly with the x1205 hardware, we use
 * rtc_time -- month 0-11, hour 0-23, yr = calendar year-epoch
 * Epoch is initialized as 2000. Time is set to UTC.
 */
static int x1205_get_datetime(struct i2c_client *client, struct rtc_time *tm,
                unsigned char reg_base)
{
    unsigned char dt_addr[2] = { 0, reg_base };
    unsigned char buf[8];
    int i;

    struct i2c_msg msgs[] = {
        {/* setup read ptr */
            .addr = client->addr,
            .len = 2,
            .buf = dt_addr
        },
        {/* read date */
            .addr = client->addr,
            .flags = I2C_M_RD,
            .len = 8,
            .buf = buf
        },
    };

    /* read date registers */
    if (i2c_transfer(client->adapter, &msgs[0], 2) != 2) {
        dev_err(&client->dev, "%s: read error\n", __func__);
        return -EIO;
    }

    dev_dbg(&client->dev,
        "%s: raw read data - sec=%02x, min=%02x, hr=%02x, "
        "mday=%02x, mon=%02x, year=%02x, wday=%02x, y2k=%02x\n",
        __func__,
        buf[0], buf[1], buf[2], buf[3],
        buf[4], buf[5], buf[6], buf[7]);

    /* Mask out the enable bits if these are alarm registers */
    if (reg_base < X1205_CCR_BASE)
        for (i = 0; i <= 4; i++)
            buf[i] &= 0x7F;

    tm->tm_sec = bcd2bin(buf[CCR_SEC]);
    tm->tm_min = bcd2bin(buf[CCR_MIN]);
    tm->tm_hour = bcd2bin(buf[CCR_HOUR] & 0x3F); /* hr is 0-23 */
    tm->tm_mday = bcd2bin(buf[CCR_MDAY]);
    tm->tm_mon = bcd2bin(buf[CCR_MONTH]) - 1; /* mon is 0-11 */
    tm->tm_year = bcd2bin(buf[CCR_YEAR])
            + (bcd2bin(buf[CCR_Y2K]) * 100) - 1900;
    tm->tm_wday = buf[CCR_WDAY];

    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 0;
}

static int x1205_get_status(struct i2c_client *client, unsigned char *sr)
{
    static unsigned char sr_addr[2] = { 0, X1205_REG_SR };

    struct i2c_msg msgs[] = {
        {     /* setup read ptr */
            .addr = client->addr,
            .len = 2,
            .buf = sr_addr
        },
        {    /* read status */
            .addr = client->addr,
            .flags = I2C_M_RD,
            .len = 1,
            .buf = sr
        },
    };

    /* read status register */
    if (i2c_transfer(client->adapter, &msgs[0], 2) != 2) {
        dev_err(&client->dev, "%s: read error\n", __func__);
        return -EIO;
    }

    return 0;
}

static int x1205_set_datetime(struct i2c_client *client, struct rtc_time *tm,
            u8 reg_base, unsigned char alm_enable)
{
    int i, xfer;
    unsigned char rdata[10] = { 0, reg_base };
    unsigned char *buf = rdata + 2;

    static const unsigned char wel[3] = { 0, X1205_REG_SR,
                        X1205_SR_WEL };

    static const unsigned char rwel[3] = { 0, X1205_REG_SR,
                        X1205_SR_WEL | X1205_SR_RWEL };

    static const unsigned char diswe[3] = { 0, X1205_REG_SR, 0 };

    dev_dbg(&client->dev,
        "%s: sec=%d min=%d hour=%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[CCR_SEC] = bin2bcd(tm->tm_sec);
    buf[CCR_MIN] = bin2bcd(tm->tm_min);

    /* set hour and 24hr bit */
    buf[CCR_HOUR] = bin2bcd(tm->tm_hour) | X1205_HR_MIL;

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

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

    /* year, since the rtc epoch*/
    buf[CCR_YEAR] = bin2bcd(tm->tm_year % 100);
    buf[CCR_WDAY] = tm->tm_wday & 0x07;
    buf[CCR_Y2K] = bin2bcd((tm->tm_year + 1900) / 100);

    /* If writing alarm registers, set compare bits on registers 0-4 */
    if (reg_base < X1205_CCR_BASE)
        for (i = 0; i <= 4; i++)
            buf[i] |= 0x80;

    /* this sequence is required to unlock the chip */
    if ((xfer = i2c_master_send(client, wel, 3)) != 3) {
        dev_err(&client->dev, "%s: wel - %d\n", __func__, xfer);
        return -EIO;
    }

    if ((xfer = i2c_master_send(client, rwel, 3)) != 3) {
        dev_err(&client->dev, "%s: rwel - %d\n", __func__, xfer);
        return -EIO;
    }

    xfer = i2c_master_send(client, rdata, sizeof(rdata));
    if (xfer != sizeof(rdata)) {
        dev_err(&client->dev,
            "%s: result=%d addr=%02x, data=%02x\n",
            __func__,
             xfer, rdata[1], rdata[2]);
        return -EIO;
    }

    /* If we wrote to the nonvolatile region, wait 10msec for write cycle*/
    if (reg_base < X1205_CCR_BASE) {
        unsigned char al0e[3] = { 0, X1205_REG_INT, 0 };

        msleep(10);

        /* ...and set or clear the AL0E bit in the INT register */

        /* Need to set RWEL again as the write has cleared it */
        xfer = i2c_master_send(client, rwel, 3);
        if (xfer != 3) {
            dev_err(&client->dev,
                "%s: aloe rwel - %d\n",
                __func__,
                xfer);
            return -EIO;
        }

        if (alm_enable)
            al0e[2] = X1205_INT_AL0E;

        xfer = i2c_master_send(client, al0e, 3);
        if (xfer != 3) {
            dev_err(&client->dev,
                "%s: al0e - %d\n",
                __func__,
                xfer);
            return -EIO;
        }

        /* and wait 10msec again for this write to complete */
        msleep(10);
    }

    /* disable further writes */
    if ((xfer = i2c_master_send(client, diswe, 3)) != 3) {
        dev_err(&client->dev, "%s: diswe - %d\n", __func__, xfer);
        return -EIO;
    }

    return 0;
}

static int x1205_fix_osc(struct i2c_client *client)
{
    int err;
    struct rtc_time tm;

    memset(&tm, 0, sizeof(tm));

    err = x1205_set_datetime(client, &tm, X1205_CCR_BASE, 0);
    if (err < 0)
        dev_err(&client->dev, "unable to restart the oscillator\n");

    return err;
}

static int x1205_get_dtrim(struct i2c_client *client, int *trim)
{
    unsigned char dtr;
    static unsigned char dtr_addr[2] = { 0, X1205_REG_DTR };

    struct i2c_msg msgs[] = {
        {   /* setup read ptr */
            .addr = client->addr,
            .len = 2,
            .buf = dtr_addr
        },
        {      /* read dtr */
            .addr = client->addr,
            .flags = I2C_M_RD,
            .len = 1,
            .buf = &dtr
        },
    };

    /* read dtr register */
    if (i2c_transfer(client->adapter, &msgs[0], 2) != 2) {
        dev_err(&client->dev, "%s: read error\n", __func__);
        return -EIO;
    }

    dev_dbg(&client->dev, "%s: raw dtr=%x\n", __func__, dtr);

    *trim = 0;

    if (dtr & X1205_DTR_DTR0)
        *trim += 20;

    if (dtr & X1205_DTR_DTR1)
        *trim += 10;

    if (dtr & X1205_DTR_DTR2)
        *trim = -*trim;

    return 0;
}

static int x1205_get_atrim(struct i2c_client *client, int *trim)
{
    s8 atr;
    static unsigned char atr_addr[2] = { 0, X1205_REG_ATR };

    struct i2c_msg msgs[] = {
        {/* setup read ptr */
            .addr = client->addr,
            .len = 2,
            .buf = atr_addr
        },
        {/* read atr */
            .addr = client->addr,
            .flags = I2C_M_RD,
            .len = 1,
            .buf = &atr
        },
    };

    /* read atr register */
    if (i2c_transfer(client->adapter, &msgs[0], 2) != 2) {
        dev_err(&client->dev, "%s: read error\n", __func__);
        return -EIO;
    }

    dev_dbg(&client->dev, "%s: raw atr=%x\n", __func__, atr);

    /* atr is a two's complement value on 6 bits,
     * perform sign extension. The formula is
     * Catr = (atr * 0.25pF) + 11.00pF.
     */
    if (atr & 0x20)
        atr |= 0xC0;

    dev_dbg(&client->dev, "%s: raw atr=%x (%d)\n", __func__, atr, atr);

    *trim = (atr * 250) + 11000;

    dev_dbg(&client->dev, "%s: real=%d\n", __func__, *trim);

    return 0;
}

struct x1205_limit
{
    unsigned char reg, mask, min, max;
};

static int x1205_validate_client(struct i2c_client *client)
{
    int i, xfer;

    /* Probe array. We will read the register at the specified
     * address and check if the given bits are zero.
     */
    static const unsigned char probe_zero_pattern[] = {
        /* register, mask */
        X1205_REG_SR,   0x18,
        X1205_REG_DTR,  0xF8,
        X1205_REG_ATR,  0xC0,
        X1205_REG_INT,  0x18,
        X1205_REG_0,    0xFF,
    };

    static const struct x1205_limit probe_limits_pattern[] = {
        /* register, mask, min, max */
        { X1205_REG_Y2K,    0xFF,   19, 20  },
        { X1205_REG_DW,     0xFF,   0,  6   },
        { X1205_REG_YR,     0xFF,   0,  99  },
        { X1205_REG_MO,     0xFF,   0,  12  },
        { X1205_REG_DT,     0xFF,   0,  31  },
        { X1205_REG_HR,     0x7F,   0,  23  },
        { X1205_REG_MN,     0xFF,   0,  59  },
        { X1205_REG_SC,     0xFF,   0,  59  },
        { X1205_REG_Y2K1,   0xFF,   19, 20  },
        { X1205_REG_Y2K0,   0xFF,   19, 20  },
    };

    /* check that registers have bits a 0 where expected */
    for (i = 0; i < ARRAY_SIZE(probe_zero_pattern); i += 2) {
        unsigned char buf;

        unsigned char addr[2] = { 0, probe_zero_pattern[i] };

        struct i2c_msg msgs[2] = {
            {
                .addr = client->addr,
                .len = 2,
                .buf = addr
            },
            {
                .addr = client->addr,
                .flags = I2C_M_RD,
                .len = 1,
                .buf = &buf
            },
        };

        if ((xfer = i2c_transfer(client->adapter, msgs, 2)) != 2) {
            dev_err(&client->dev,
                "%s: could not read register %x\n",
                __func__, probe_zero_pattern[i]);

            return -EIO;
        }

        if ((buf & probe_zero_pattern[i+1]) != 0) {
            dev_err(&client->dev,
                "%s: register=%02x, zero pattern=%d, value=%x\n",
                __func__, probe_zero_pattern[i], i, buf);

            return -ENODEV;
        }
    }

    /* check limits (only registers with bcd values) */
    for (i = 0; i < ARRAY_SIZE(probe_limits_pattern); i++) {
        unsigned char reg, value;

        unsigned char addr[2] = { 0, probe_limits_pattern[i].reg };

        struct i2c_msg msgs[2] = {
            {
                .addr = client->addr,
                .len = 2,
                .buf = addr
            },
            {
                .addr = client->addr,
                .flags = I2C_M_RD,
                .len = 1,
                .buf = &reg
            },
        };

        if ((xfer = i2c_transfer(client->adapter, msgs, 2)) != 2) {
            dev_err(&client->dev,
                "%s: could not read register %x\n",
                __func__, probe_limits_pattern[i].reg);

            return -EIO;
        }

        value = bcd2bin(reg & probe_limits_pattern[i].mask);

        if (value > probe_limits_pattern[i].max ||
            value < probe_limits_pattern[i].min) {
            dev_dbg(&client->dev,
                "%s: register=%x, lim pattern=%d, value=%d\n",
                __func__, probe_limits_pattern[i].reg,
                i, value);

            return -ENODEV;
        }
    }

    return 0;
}

static int x1205_rtc_read_alarm(struct device *dev, struct rtc_wkalrm *alrm)
{
    int err;
    unsigned char intreg, status;
    static unsigned char int_addr[2] = { 0, X1205_REG_INT };
    struct i2c_client *client = to_i2c_client(dev);
    struct i2c_msg msgs[] = {
        { /* setup read ptr */
            .addr = client->addr,
            .len = 2,
            .buf = int_addr
        },
        {/* read INT register */

            .addr = client->addr,
            .flags = I2C_M_RD,
            .len = 1,
            .buf = &intreg
        },
    };

    /* read interrupt register and status register */
    if (i2c_transfer(client->adapter, &msgs[0], 2) != 2) {
        dev_err(&client->dev, "%s: read error\n", __func__);
        return -EIO;
    }
    err = x1205_get_status(client, &status);
    if (err == 0) {
        alrm->pending = (status & X1205_SR_AL0) ? 1 : 0;
        alrm->enabled = (intreg & X1205_INT_AL0E) ? 1 : 0;
        err = x1205_get_datetime(client, &alrm->time, X1205_ALM0_BASE);
    }
    return err;
}

static int x1205_rtc_set_alarm(struct device *dev, struct rtc_wkalrm *alrm)
{
    return x1205_set_datetime(to_i2c_client(dev),
        &alrm->time, X1205_ALM0_BASE, alrm->enabled);
}

static int x1205_rtc_read_time(struct device *dev, struct rtc_time *tm)
{
    return x1205_get_datetime(to_i2c_client(dev),
        tm, X1205_CCR_BASE);
}

static int x1205_rtc_set_time(struct device *dev, struct rtc_time *tm)
{
    return x1205_set_datetime(to_i2c_client(dev),
        tm, X1205_CCR_BASE, 0);
}

static int x1205_rtc_proc(struct device *dev, struct seq_file *seq)
{
    int err, dtrim, atrim;

    if ((err = x1205_get_dtrim(to_i2c_client(dev), &dtrim)) == 0)
        seq_printf(seq, "digital_trim\t: %d ppm\n", dtrim);

    if ((err = x1205_get_atrim(to_i2c_client(dev), &atrim)) == 0)
        seq_printf(seq, "analog_trim\t: %d.%02d pF\n",
            atrim / 1000, atrim % 1000);
    return 0;
}

static const struct rtc_class_ops x1205_rtc_ops = {
    .proc       = x1205_rtc_proc,
    .read_time  = x1205_rtc_read_time,
    .set_time   = x1205_rtc_set_time,
    .read_alarm = x1205_rtc_read_alarm,
    .set_alarm  = x1205_rtc_set_alarm,
};

static ssize_t x1205_sysfs_show_atrim(struct device *dev,
                struct device_attribute *attr, char *buf)
{
    int err, atrim;

    err = x1205_get_atrim(to_i2c_client(dev), &atrim);
    if (err)
        return err;

    return sprintf(buf, "%d.%02d pF\n", atrim / 1000, atrim % 1000);
}
static DEVICE_ATTR(atrim, S_IRUGO, x1205_sysfs_show_atrim, NULL);

static ssize_t x1205_sysfs_show_dtrim(struct device *dev,
                struct device_attribute *attr, char *buf)
{
    int err, dtrim;

    err = x1205_get_dtrim(to_i2c_client(dev), &dtrim);
    if (err)
        return err;

    return sprintf(buf, "%d ppm\n", dtrim);
}
static DEVICE_ATTR(dtrim, S_IRUGO, x1205_sysfs_show_dtrim, NULL);

static int x1205_sysfs_register(struct device *dev)
{
    int err;

    err = device_create_file(dev, &dev_attr_atrim);
    if (err)
        return err;

    err = device_create_file(dev, &dev_attr_dtrim);
    if (err)
        device_remove_file(dev, &dev_attr_atrim);

    return err;
}

static void x1205_sysfs_unregister(struct device *dev)
{
    device_remove_file(dev, &dev_attr_atrim);
    device_remove_file(dev, &dev_attr_dtrim);
}


static int x1205_probe(struct i2c_client *client,
            const struct i2c_device_id *id)
{
    int err = 0;
    unsigned char sr;
    struct rtc_device *rtc;

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

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

    if (x1205_validate_client(client) < 0)
        return -ENODEV;

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

    rtc = rtc_device_register(x1205_driver.driver.name, &client->dev,
                &x1205_rtc_ops, THIS_MODULE);

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

    i2c_set_clientdata(client, rtc);

    /* Check for power failures and eventually enable the osc */
    if ((err = x1205_get_status(client, &sr)) == 0) {
        if (sr & X1205_SR_RTCF) {
            dev_err(&client->dev,
                "power failure detected, "
                "please set the clock\n");
            udelay(50);
            x1205_fix_osc(client);
        }
    }
    else
        dev_err(&client->dev, "couldn't read status\n");

    err = x1205_sysfs_register(&client->dev);
    if (err)
        goto exit_devreg;

    return 0;

exit_devreg:
    rtc_device_unregister(rtc);

    return err;
}

static int x1205_remove(struct i2c_client *client)
{
    struct rtc_device *rtc = i2c_get_clientdata(client);

    rtc_device_unregister(rtc);
    x1205_sysfs_unregister(&client->dev);
    return 0;
}

static const struct i2c_device_id x1205_id[] = {
    { "x1205", 0 },
    { }
};
MODULE_DEVICE_TABLE(i2c, x1205_id);

static struct i2c_driver x1205_driver = {
    .driver     = {
        .name   = "rtc-x1205",
    },
    .probe      = x1205_probe,
    .remove     = x1205_remove,
    .id_table   = x1205_id,
};

module_i2c_driver(x1205_driver);

MODULE_AUTHOR(
    "Karen Spearel <kas111 at gmail dot com>, "
    "Alessandro Zummo <[email protected]>");
MODULE_DESCRIPTION("Xicor/Intersil X1205 RTC driver");
MODULE_LICENSE("GPL");
MODULE_VERSION(DRV_VERSION);