rtc-m48t86.c

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/*
 * ST M48T86 / Dallas DS12887 RTC driver
 * Copyright (c) 2006 Tower Technologies
 *
 * Author: 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.
 *
 * This drivers only supports the clock running in BCD and 24H mode.
 * If it will be ever adapted to binary and 12H mode, care must be taken
 * to not introduce bugs.
 */

#include <linux/module.h>
#include <linux/rtc.h>
#include <linux/platform_device.h>
#include <linux/m48t86.h>
#include <linux/bcd.h>

#define M48T86_REG_SEC      0x00
#define M48T86_REG_SECALRM  0x01
#define M48T86_REG_MIN      0x02
#define M48T86_REG_MINALRM  0x03
#define M48T86_REG_HOUR     0x04
#define M48T86_REG_HOURALRM 0x05
#define M48T86_REG_DOW      0x06 /* 1 = sunday */
#define M48T86_REG_DOM      0x07
#define M48T86_REG_MONTH    0x08 /* 1 - 12 */
#define M48T86_REG_YEAR     0x09 /* 0 - 99 */
#define M48T86_REG_A        0x0A
#define M48T86_REG_B        0x0B
#define M48T86_REG_C        0x0C
#define M48T86_REG_D        0x0D

#define M48T86_REG_B_H24    (1 << 1)
#define M48T86_REG_B_DM     (1 << 2)
#define M48T86_REG_B_SET    (1 << 7)
#define M48T86_REG_D_VRT    (1 << 7)

#define DRV_VERSION "0.1"


static int m48t86_rtc_read_time(struct device *dev, struct rtc_time *tm)
{
    unsigned char reg;
    struct platform_device *pdev = to_platform_device(dev);
    struct m48t86_ops *ops = pdev->dev.platform_data;

    reg = ops->readbyte(M48T86_REG_B);

    if (reg & M48T86_REG_B_DM) {
        /* data (binary) mode */
        tm->tm_sec  = ops->readbyte(M48T86_REG_SEC);
        tm->tm_min  = ops->readbyte(M48T86_REG_MIN);
        tm->tm_hour = ops->readbyte(M48T86_REG_HOUR) & 0x3F;
        tm->tm_mday = ops->readbyte(M48T86_REG_DOM);
        /* tm_mon is 0-11 */
        tm->tm_mon  = ops->readbyte(M48T86_REG_MONTH) - 1;
        tm->tm_year = ops->readbyte(M48T86_REG_YEAR) + 100;
        tm->tm_wday = ops->readbyte(M48T86_REG_DOW);
    } else {
        /* bcd mode */
        tm->tm_sec  = bcd2bin(ops->readbyte(M48T86_REG_SEC));
        tm->tm_min  = bcd2bin(ops->readbyte(M48T86_REG_MIN));
        tm->tm_hour = bcd2bin(ops->readbyte(M48T86_REG_HOUR) & 0x3F);
        tm->tm_mday = bcd2bin(ops->readbyte(M48T86_REG_DOM));
        /* tm_mon is 0-11 */
        tm->tm_mon  = bcd2bin(ops->readbyte(M48T86_REG_MONTH)) - 1;
        tm->tm_year = bcd2bin(ops->readbyte(M48T86_REG_YEAR)) + 100;
        tm->tm_wday = bcd2bin(ops->readbyte(M48T86_REG_DOW));
    }

    /* correct the hour if the clock is in 12h mode */
    if (!(reg & M48T86_REG_B_H24))
        if (ops->readbyte(M48T86_REG_HOUR) & 0x80)
            tm->tm_hour += 12;

    return rtc_valid_tm(tm);
}

static int m48t86_rtc_set_time(struct device *dev, struct rtc_time *tm)
{
    unsigned char reg;
    struct platform_device *pdev = to_platform_device(dev);
    struct m48t86_ops *ops = pdev->dev.platform_data;

    reg = ops->readbyte(M48T86_REG_B);

    /* update flag and 24h mode */
    reg |= M48T86_REG_B_SET | M48T86_REG_B_H24;
    ops->writebyte(reg, M48T86_REG_B);

    if (reg & M48T86_REG_B_DM) {
        /* data (binary) mode */
        ops->writebyte(tm->tm_sec, M48T86_REG_SEC);
        ops->writebyte(tm->tm_min, M48T86_REG_MIN);
        ops->writebyte(tm->tm_hour, M48T86_REG_HOUR);
        ops->writebyte(tm->tm_mday, M48T86_REG_DOM);
        ops->writebyte(tm->tm_mon + 1, M48T86_REG_MONTH);
        ops->writebyte(tm->tm_year % 100, M48T86_REG_YEAR);
        ops->writebyte(tm->tm_wday, M48T86_REG_DOW);
    } else {
        /* bcd mode */
        ops->writebyte(bin2bcd(tm->tm_sec), M48T86_REG_SEC);
        ops->writebyte(bin2bcd(tm->tm_min), M48T86_REG_MIN);
        ops->writebyte(bin2bcd(tm->tm_hour), M48T86_REG_HOUR);
        ops->writebyte(bin2bcd(tm->tm_mday), M48T86_REG_DOM);
        ops->writebyte(bin2bcd(tm->tm_mon + 1), M48T86_REG_MONTH);
        ops->writebyte(bin2bcd(tm->tm_year % 100), M48T86_REG_YEAR);
        ops->writebyte(bin2bcd(tm->tm_wday), M48T86_REG_DOW);
    }

    /* update ended */
    reg &= ~M48T86_REG_B_SET;
    ops->writebyte(reg, M48T86_REG_B);

    return 0;
}

static int m48t86_rtc_proc(struct device *dev, struct seq_file *seq)
{
    unsigned char reg;
    struct platform_device *pdev = to_platform_device(dev);
    struct m48t86_ops *ops = pdev->dev.platform_data;

    reg = ops->readbyte(M48T86_REG_B);

    seq_printf(seq, "mode\t\t: %s\n",
         (reg & M48T86_REG_B_DM) ? "binary" : "bcd");

    reg = ops->readbyte(M48T86_REG_D);

    seq_printf(seq, "battery\t\t: %s\n",
         (reg & M48T86_REG_D_VRT) ? "ok" : "exhausted");

    return 0;
}

static const struct rtc_class_ops m48t86_rtc_ops = {
    .read_time  = m48t86_rtc_read_time,
    .set_time   = m48t86_rtc_set_time,
    .proc       = m48t86_rtc_proc,
};

static int __devinit m48t86_rtc_probe(struct platform_device *dev)
{
    unsigned char reg;
    struct m48t86_ops *ops = dev->dev.platform_data;
    struct rtc_device *rtc = rtc_device_register("m48t86",
                &dev->dev, &m48t86_rtc_ops, THIS_MODULE);

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

    platform_set_drvdata(dev, rtc);

    /* read battery status */
    reg = ops->readbyte(M48T86_REG_D);
    dev_info(&dev->dev, "battery %s\n",
        (reg & M48T86_REG_D_VRT) ? "ok" : "exhausted");

    return 0;
}

static int __devexit m48t86_rtc_remove(struct platform_device *dev)
{
    struct rtc_device *rtc = platform_get_drvdata(dev);

    if (rtc)
        rtc_device_unregister(rtc);

    platform_set_drvdata(dev, NULL);

    return 0;
}

static struct platform_driver m48t86_rtc_platform_driver = {
    .driver     = {
        .name   = "rtc-m48t86",
        .owner  = THIS_MODULE,
    },
    .probe      = m48t86_rtc_probe,
    .remove     = __devexit_p(m48t86_rtc_remove),
};

module_platform_driver(m48t86_rtc_platform_driver);

MODULE_AUTHOR("Alessandro Zummo <[email protected]>");
MODULE_DESCRIPTION("M48T86 RTC driver");
MODULE_LICENSE("GPL");
MODULE_VERSION(DRV_VERSION);
MODULE_ALIAS("platform:rtc-m48t86");