rtc-ds1302.c

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/*
 * Dallas DS1302 RTC Support
 *
 *  Copyright (C) 2002 David McCullough
 *  Copyright (C) 2003 - 2007 Paul Mundt
 *
 * This file is subject to the terms and conditions of the GNU General Public
 * License version 2. See the file "COPYING" in the main directory of
 * this archive for more details.
 */

#include <linux/init.h>
#include <linux/module.h>
#include <linux/kernel.h>
#include <linux/platform_device.h>
#include <linux/rtc.h>
#include <linux/io.h>
#include <linux/bcd.h>

#define DRV_NAME    "rtc-ds1302"
#define DRV_VERSION "0.1.1"

#define RTC_CMD_READ    0x81        /* Read command */
#define RTC_CMD_WRITE   0x80        /* Write command */

#define RTC_ADDR_RAM0   0x20        /* Address of RAM0 */
#define RTC_ADDR_TCR    0x08        /* Address of trickle charge register */
#define RTC_ADDR_YEAR   0x06        /* Address of year register */
#define RTC_ADDR_DAY    0x05        /* Address of day of week register */
#define RTC_ADDR_MON    0x04        /* Address of month register */
#define RTC_ADDR_DATE   0x03        /* Address of day of month register */
#define RTC_ADDR_HOUR   0x02        /* Address of hour register */
#define RTC_ADDR_MIN    0x01        /* Address of minute register */
#define RTC_ADDR_SEC    0x00        /* Address of second register */

#ifdef CONFIG_SH_SECUREEDGE5410
#include <asm/rtc.h>
#include <mach/secureedge5410.h>

#define RTC_RESET   0x1000
#define RTC_IODATA  0x0800
#define RTC_SCLK    0x0400

#define set_dp(x)   SECUREEDGE_WRITE_IOPORT(x, 0x1c00)
#define get_dp()    SECUREEDGE_READ_IOPORT()
#define ds1302_set_tx()
#define ds1302_set_rx()

static inline int ds1302_hw_init(void)
{
    return 0;
}

static inline void ds1302_reset(void)
{
    set_dp(get_dp() & ~(RTC_RESET | RTC_IODATA | RTC_SCLK));
}

static inline void ds1302_clock(void)
{
    set_dp(get_dp() | RTC_SCLK);    /* clock high */
    set_dp(get_dp() & ~RTC_SCLK);   /* clock low */
}

static inline void ds1302_start(void)
{
    set_dp(get_dp() | RTC_RESET);
}

static inline void ds1302_stop(void)
{
    set_dp(get_dp() & ~RTC_RESET);
}

static inline void ds1302_txbit(int bit)
{
    set_dp((get_dp() & ~RTC_IODATA) | (bit ? RTC_IODATA : 0));
}

static inline int ds1302_rxbit(void)
{
    return !!(get_dp() & RTC_IODATA);
}

#else
#error "Add support for your platform"
#endif

static void ds1302_sendbits(unsigned int val)
{
    int i;

    ds1302_set_tx();

    for (i = 8; (i); i--, val >>= 1) {
        ds1302_txbit(val & 0x1);
        ds1302_clock();
    }
}

static unsigned int ds1302_recvbits(void)
{
    unsigned int val;
    int i;

    ds1302_set_rx();

    for (i = 0, val = 0; (i < 8); i++) {
        val |= (ds1302_rxbit() << i);
        ds1302_clock();
    }

    return val;
}

static unsigned int ds1302_readbyte(unsigned int addr)
{
    unsigned int val;

    ds1302_reset();

    ds1302_start();
    ds1302_sendbits(((addr & 0x3f) << 1) | RTC_CMD_READ);
    val = ds1302_recvbits();
    ds1302_stop();

    return val;
}

static void ds1302_writebyte(unsigned int addr, unsigned int val)
{
    ds1302_reset();

    ds1302_start();
    ds1302_sendbits(((addr & 0x3f) << 1) | RTC_CMD_WRITE);
    ds1302_sendbits(val);
    ds1302_stop();
}

static int ds1302_rtc_read_time(struct device *dev, struct rtc_time *tm)
{
    tm->tm_sec  = bcd2bin(ds1302_readbyte(RTC_ADDR_SEC));
    tm->tm_min  = bcd2bin(ds1302_readbyte(RTC_ADDR_MIN));
    tm->tm_hour = bcd2bin(ds1302_readbyte(RTC_ADDR_HOUR));
    tm->tm_wday = bcd2bin(ds1302_readbyte(RTC_ADDR_DAY));
    tm->tm_mday = bcd2bin(ds1302_readbyte(RTC_ADDR_DATE));
    tm->tm_mon  = bcd2bin(ds1302_readbyte(RTC_ADDR_MON)) - 1;
    tm->tm_year = bcd2bin(ds1302_readbyte(RTC_ADDR_YEAR));

    if (tm->tm_year < 70)
        tm->tm_year += 100;

    dev_dbg(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 + 1, tm->tm_year, tm->tm_wday);

    return rtc_valid_tm(tm);
}

static int ds1302_rtc_set_time(struct device *dev, struct rtc_time *tm)
{
    /* Stop RTC */
    ds1302_writebyte(RTC_ADDR_SEC, ds1302_readbyte(RTC_ADDR_SEC) | 0x80);

    ds1302_writebyte(RTC_ADDR_SEC, bin2bcd(tm->tm_sec));
    ds1302_writebyte(RTC_ADDR_MIN, bin2bcd(tm->tm_min));
    ds1302_writebyte(RTC_ADDR_HOUR, bin2bcd(tm->tm_hour));
    ds1302_writebyte(RTC_ADDR_DAY, bin2bcd(tm->tm_wday));
    ds1302_writebyte(RTC_ADDR_DATE, bin2bcd(tm->tm_mday));
    ds1302_writebyte(RTC_ADDR_MON, bin2bcd(tm->tm_mon + 1));
    ds1302_writebyte(RTC_ADDR_YEAR, bin2bcd(tm->tm_year % 100));

    /* Start RTC */
    ds1302_writebyte(RTC_ADDR_SEC, ds1302_readbyte(RTC_ADDR_SEC) & ~0x80);

    return 0;
}

static int ds1302_rtc_ioctl(struct device *dev, unsigned int cmd,
                unsigned long arg)
{
    switch (cmd) {
#ifdef RTC_SET_CHARGE
    case RTC_SET_CHARGE:
    {
        int tcs_val;

        if (copy_from_user(&tcs_val, (int __user *)arg, sizeof(int)))
            return -EFAULT;

        ds1302_writebyte(RTC_ADDR_TCR, (0xa0 | tcs_val * 0xf));
        return 0;
    }
#endif
    }

    return -ENOIOCTLCMD;
}

static struct rtc_class_ops ds1302_rtc_ops = {
    .read_time  = ds1302_rtc_read_time,
    .set_time   = ds1302_rtc_set_time,
    .ioctl      = ds1302_rtc_ioctl,
};

static int __init ds1302_rtc_probe(struct platform_device *pdev)
{
    struct rtc_device *rtc;

    if (ds1302_hw_init()) {
        dev_err(&pdev->dev, "Failed to init communication channel");
        return -EINVAL;
    }

    /* Reset */
    ds1302_reset();

    /* Write a magic value to the DS1302 RAM, and see if it sticks. */
    ds1302_writebyte(RTC_ADDR_RAM0, 0x42);
    if (ds1302_readbyte(RTC_ADDR_RAM0) != 0x42) {
        dev_err(&pdev->dev, "Failed to probe");
        return -ENODEV;
    }

    rtc = rtc_device_register("ds1302", &pdev->dev,
                       &ds1302_rtc_ops, THIS_MODULE);
    if (IS_ERR(rtc))
        return PTR_ERR(rtc);

    platform_set_drvdata(pdev, rtc);

    return 0;
}

static int __devexit ds1302_rtc_remove(struct platform_device *pdev)
{
    struct rtc_device *rtc = platform_get_drvdata(pdev);

    rtc_device_unregister(rtc);
    platform_set_drvdata(pdev, NULL);

    return 0;
}

static struct platform_driver ds1302_platform_driver = {
    .driver     = {
        .name   = DRV_NAME,
        .owner  = THIS_MODULE,
    },
    .remove     = __devexit_p(ds1302_rtc_remove),
};

static int __init ds1302_rtc_init(void)
{
    return platform_driver_probe(&ds1302_platform_driver, ds1302_rtc_probe);
}

static void __exit ds1302_rtc_exit(void)
{
    platform_driver_unregister(&ds1302_platform_driver);
}

module_init(ds1302_rtc_init);
module_exit(ds1302_rtc_exit);

MODULE_DESCRIPTION("Dallas DS1302 RTC driver");
MODULE_VERSION(DRV_VERSION);
MODULE_AUTHOR("Paul Mundt, David McCullough");
MODULE_LICENSE("GPL v2");