rtc-em3027.c

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/*
 * An rtc/i2c driver for the EM Microelectronic EM3027
 * Copyright 2011 CompuLab, Ltd.
 *
 * Author: Mike Rapoport <[email protected]>
 *
 * Based on rtc-ds1672.c by Alessandro Zummo <[email protected]>
 *
 * 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/rtc.h>
#include <linux/bcd.h>
#include <linux/module.h>

/* Registers */
#define EM3027_REG_ON_OFF_CTRL  0x00
#define EM3027_REG_IRQ_CTRL 0x01
#define EM3027_REG_IRQ_FLAGS    0x02
#define EM3027_REG_STATUS   0x03
#define EM3027_REG_RST_CTRL 0x04

#define EM3027_REG_WATCH_SEC    0x08
#define EM3027_REG_WATCH_MIN    0x09
#define EM3027_REG_WATCH_HOUR   0x0a
#define EM3027_REG_WATCH_DATE   0x0b
#define EM3027_REG_WATCH_DAY    0x0c
#define EM3027_REG_WATCH_MON    0x0d
#define EM3027_REG_WATCH_YEAR   0x0e

#define EM3027_REG_ALARM_SEC    0x10
#define EM3027_REG_ALARM_MIN    0x11
#define EM3027_REG_ALARM_HOUR   0x12
#define EM3027_REG_ALARM_DATE   0x13
#define EM3027_REG_ALARM_DAY    0x14
#define EM3027_REG_ALARM_MON    0x15
#define EM3027_REG_ALARM_YEAR   0x16

static struct i2c_driver em3027_driver;

static int em3027_get_time(struct device *dev, struct rtc_time *tm)
{
    struct i2c_client *client = to_i2c_client(dev);

    unsigned char addr = EM3027_REG_WATCH_SEC;
    unsigned char buf[7];

    struct i2c_msg msgs[] = {
        {/* setup read addr */
            .addr = client->addr,
            .len = 1,
            .buf = &addr
        },
        {/* read time/date */
            .addr = client->addr,
            .flags = I2C_M_RD,
            .len = 7,
            .buf = buf
        },
    };

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

    tm->tm_sec  = bcd2bin(buf[0]);
    tm->tm_min  = bcd2bin(buf[1]);
    tm->tm_hour = bcd2bin(buf[2]);
    tm->tm_mday = bcd2bin(buf[3]);
    tm->tm_wday = bcd2bin(buf[4]);
    tm->tm_mon  = bcd2bin(buf[5]);
    tm->tm_year = bcd2bin(buf[6]) + 100;

    return 0;
}

static int em3027_set_time(struct device *dev, struct rtc_time *tm)
{
    struct i2c_client *client = to_i2c_client(dev);
    unsigned char buf[8];

    struct i2c_msg msg = {
        .addr = client->addr,
        .len = 8,
        .buf = buf, /* write time/date */
    };

    buf[0] = EM3027_REG_WATCH_SEC;
    buf[1] = bin2bcd(tm->tm_sec);
    buf[2] = bin2bcd(tm->tm_min);
    buf[3] = bin2bcd(tm->tm_hour);
    buf[4] = bin2bcd(tm->tm_mday);
    buf[5] = bin2bcd(tm->tm_wday);
    buf[6] = bin2bcd(tm->tm_mon);
    buf[7] = bin2bcd(tm->tm_year % 100);

    /* write time/date registers */
    if ((i2c_transfer(client->adapter, &msg, 1)) != 1) {
        dev_err(&client->dev, "%s: write error\n", __func__);
        return -EIO;
    }

    return 0;
}

static const struct rtc_class_ops em3027_rtc_ops = {
    .read_time = em3027_get_time,
    .set_time = em3027_set_time,
};

static int em3027_probe(struct i2c_client *client,
            const struct i2c_device_id *id)
{
    struct rtc_device *rtc;

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

    rtc = rtc_device_register(em3027_driver.driver.name, &client->dev,
                  &em3027_rtc_ops, THIS_MODULE);
    if (IS_ERR(rtc))
        return PTR_ERR(rtc);

    i2c_set_clientdata(client, rtc);

    return 0;
}

static int em3027_remove(struct i2c_client *client)
{
    struct rtc_device *rtc = i2c_get_clientdata(client);

    if (rtc)
        rtc_device_unregister(rtc);

    return 0;
}

static struct i2c_device_id em3027_id[] = {
    { "em3027", 0 },
    { }
};

static struct i2c_driver em3027_driver = {
    .driver = {
           .name = "rtc-em3027",
    },
    .probe = &em3027_probe,
    .remove = &em3027_remove,
    .id_table = em3027_id,
};

module_i2c_driver(em3027_driver);

MODULE_AUTHOR("Mike Rapoport <[email protected]>");
MODULE_DESCRIPTION("EM Microelectronic EM3027 RTC driver");
MODULE_LICENSE("GPL");