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/*

 * ST M48T86 / Dallas DS12887 RTC driver

 * Copyright (c) 2006 Tower Technologies

 *

 * Author: Alessandro Zummo <a.zummo@towertech.it>

 *

 * 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 0;

}

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),

};

static int __init m48t86_rtc_init(void)

{

        return platform_driver_register(&m48t86_rtc_platform_driver);

}

static void __exit m48t86_rtc_exit(void)

{

        platform_driver_unregister(&m48t86_rtc_platform_driver);

}

MODULE_AUTHOR("Alessandro Zummo <a.zummo@towertech.it>");

MODULE_DESCRIPTION("M48T86 RTC driver");

MODULE_LICENSE("GPL");

MODULE_VERSION(DRV_VERSION);

module_init(m48t86_rtc_init);

module_exit(m48t86_rtc_exit);