ds1302.c

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/*!***************************************************************************
*!
*! FILE NAME  : ds1302.c
*!
*! DESCRIPTION: Implements an interface for the DS1302 RTC
*!
*! Functions exported: ds1302_readreg, ds1302_writereg, ds1302_init, get_rtc_status
*!
*! ---------------------------------------------------------------------------
*!
*! (C) Copyright 1999, 2000, 2001  Axis Communications AB, LUND, SWEDEN
*!
*!***************************************************************************/


#include <linux/fs.h>
#include <linux/init.h>
#include <linux/mm.h>
#include <linux/module.h>
#include <linux/miscdevice.h>
#include <linux/delay.h>
#include <linux/bcd.h>
#include <linux/mutex.h>
#include <linux/uaccess.h>
#include <linux/io.h>

#include <asm/rtc.h>
#if defined(CONFIG_M32R)
#include <asm/m32r.h>
#endif

#define RTC_MAJOR_NR 121 /* local major, change later */

static DEFINE_MUTEX(rtc_mutex);
static const char ds1302_name[] = "ds1302";

/* Send 8 bits. */
static void
out_byte_rtc(unsigned int reg_addr, unsigned char x)
{
    //RST H
    outw(0x0001,(unsigned long)PLD_RTCRSTODT);
    //write data
    outw(((x<<8)|(reg_addr&0xff)),(unsigned long)PLD_RTCWRDATA);
    //WE
    outw(0x0002,(unsigned long)PLD_RTCCR);
    //wait
    while(inw((unsigned long)PLD_RTCCR));

    //RST L
    outw(0x0000,(unsigned long)PLD_RTCRSTODT);

}

static unsigned char
in_byte_rtc(unsigned int reg_addr)
{
    unsigned char retval;

    //RST H
    outw(0x0001,(unsigned long)PLD_RTCRSTODT);
    //write data
    outw((reg_addr&0xff),(unsigned long)PLD_RTCRDDATA);
    //RE
    outw(0x0001,(unsigned long)PLD_RTCCR);
    //wait
    while(inw((unsigned long)PLD_RTCCR));

    //read data
    retval=(inw((unsigned long)PLD_RTCRDDATA) & 0xff00)>>8;

    //RST L
    outw(0x0000,(unsigned long)PLD_RTCRSTODT);

    return retval;
}

/* Enable writing. */

static void
ds1302_wenable(void)
{
    out_byte_rtc(0x8e,0x00);
}

/* Disable writing. */

static void
ds1302_wdisable(void)
{
    out_byte_rtc(0x8e,0x80);
}



/* Read a byte from the selected register in the DS1302. */

unsigned char
ds1302_readreg(int reg)
{
    unsigned char x;

    x=in_byte_rtc((0x81 | (reg << 1))); /* read register */

    return x;
}

/* Write a byte to the selected register. */

void
ds1302_writereg(int reg, unsigned char val)
{
    ds1302_wenable();
    out_byte_rtc((0x80 | (reg << 1)),val);
    ds1302_wdisable();
}

void
get_rtc_time(struct rtc_time *rtc_tm)
{
    unsigned long flags;

    local_irq_save(flags);

    rtc_tm->tm_sec = CMOS_READ(RTC_SECONDS);
    rtc_tm->tm_min = CMOS_READ(RTC_MINUTES);
    rtc_tm->tm_hour = CMOS_READ(RTC_HOURS);
    rtc_tm->tm_mday = CMOS_READ(RTC_DAY_OF_MONTH);
    rtc_tm->tm_mon = CMOS_READ(RTC_MONTH);
    rtc_tm->tm_year = CMOS_READ(RTC_YEAR);

    local_irq_restore(flags);

    rtc_tm->tm_sec = bcd2bin(rtc_tm->tm_sec);
    rtc_tm->tm_min = bcd2bin(rtc_tm->tm_min);
    rtc_tm->tm_hour = bcd2bin(rtc_tm->tm_hour);
    rtc_tm->tm_mday = bcd2bin(rtc_tm->tm_mday);
    rtc_tm->tm_mon = bcd2bin(rtc_tm->tm_mon);
    rtc_tm->tm_year = bcd2bin(rtc_tm->tm_year);

    /*
     * Account for differences between how the RTC uses the values
     * and how they are defined in a struct rtc_time;
     */

    if (rtc_tm->tm_year <= 69)
        rtc_tm->tm_year += 100;

    rtc_tm->tm_mon--;
}

static unsigned char days_in_mo[] =
    {0, 31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31};

/* ioctl that supports RTC_RD_TIME and RTC_SET_TIME (read and set time/date). */

static long rtc_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
{
    unsigned long flags;

    switch(cmd) {
        case RTC_RD_TIME:   /* read the time/date from RTC  */
        {
            struct rtc_time rtc_tm;

            memset(&rtc_tm, 0, sizeof (struct rtc_time));
            mutex_lock(&rtc_mutex);
            get_rtc_time(&rtc_tm);
            mutex_unlock(&rtc_mutex);
            if (copy_to_user((struct rtc_time*)arg, &rtc_tm, sizeof(struct rtc_time)))
                return -EFAULT;
            return 0;
        }

        case RTC_SET_TIME:  /* set the RTC */
        {
            struct rtc_time rtc_tm;
            unsigned char mon, day, hrs, min, sec, leap_yr;
            unsigned int yrs;

            if (!capable(CAP_SYS_TIME))
                return -EPERM;

            if (copy_from_user(&rtc_tm, (struct rtc_time*)arg, sizeof(struct rtc_time)))
                return -EFAULT;

            yrs = rtc_tm.tm_year + 1900;
            mon = rtc_tm.tm_mon + 1;   /* tm_mon starts at zero */
            day = rtc_tm.tm_mday;
            hrs = rtc_tm.tm_hour;
            min = rtc_tm.tm_min;
            sec = rtc_tm.tm_sec;


            if ((yrs < 1970) || (yrs > 2069))
                return -EINVAL;

            leap_yr = ((!(yrs % 4) && (yrs % 100)) || !(yrs % 400));

            if ((mon > 12) || (day == 0))
                return -EINVAL;

            if (day > (days_in_mo[mon] + ((mon == 2) && leap_yr)))
                return -EINVAL;

            if ((hrs >= 24) || (min >= 60) || (sec >= 60))
                return -EINVAL;

            if (yrs >= 2000)
                yrs -= 2000;    /* RTC (0, 1, ... 69) */
            else
                yrs -= 1900;    /* RTC (70, 71, ... 99) */

            sec = bin2bcd(sec);
            min = bin2bcd(min);
            hrs = bin2bcd(hrs);
            day = bin2bcd(day);
            mon = bin2bcd(mon);
            yrs = bin2bcd(yrs);

            mutex_lock(&rtc_mutex);
            local_irq_save(flags);
            CMOS_WRITE(yrs, RTC_YEAR);
            CMOS_WRITE(mon, RTC_MONTH);
            CMOS_WRITE(day, RTC_DAY_OF_MONTH);
            CMOS_WRITE(hrs, RTC_HOURS);
            CMOS_WRITE(min, RTC_MINUTES);
            CMOS_WRITE(sec, RTC_SECONDS);
            local_irq_restore(flags);
            mutex_unlock(&rtc_mutex);

            /* Notice that at this point, the RTC is updated but
             * the kernel is still running with the old time.
             * You need to set that separately with settimeofday
             * or adjtimex.
             */
            return 0;
        }

        case RTC_SET_CHARGE: /* set the RTC TRICKLE CHARGE register */
        {
            int tcs_val;

            if (!capable(CAP_SYS_TIME))
                return -EPERM;

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

            mutex_lock(&rtc_mutex);
            tcs_val = RTC_TCR_PATTERN | (tcs_val & 0x0F);
            ds1302_writereg(RTC_TRICKLECHARGER, tcs_val);
            mutex_unlock(&rtc_mutex);
            return 0;
        }
        default:
            return -EINVAL;
    }
}

int
get_rtc_status(char *buf)
{
    char *p;
    struct rtc_time tm;

    p = buf;

    get_rtc_time(&tm);

    /*
     * There is no way to tell if the luser has the RTC set for local
     * time or for Universal Standard Time (GMT). Probably local though.
     */

    p += sprintf(p,
        "rtc_time\t: %02d:%02d:%02d\n"
        "rtc_date\t: %04d-%02d-%02d\n",
        tm.tm_hour, tm.tm_min, tm.tm_sec,
        tm.tm_year + 1900, tm.tm_mon + 1, tm.tm_mday);

    return  p - buf;
}


/* The various file operations we support. */

static const struct file_operations rtc_fops = {
    .owner      = THIS_MODULE,
    .unlocked_ioctl = rtc_ioctl,
    .llseek     = noop_llseek,
};

/* Probe for the chip by writing something to its RAM and try reading it back. */

#define MAGIC_PATTERN 0x42

static int __init
ds1302_probe(void)
{
    int retval, res, baur;

    baur=(boot_cpu_data.bus_clock/(2*1000*1000));

    printk("%s: Set PLD_RTCBAUR = %d\n", ds1302_name,baur);

    outw(0x0000,(unsigned long)PLD_RTCCR);
    outw(0x0000,(unsigned long)PLD_RTCRSTODT);
    outw(baur,(unsigned long)PLD_RTCBAUR);

    /* Try to talk to timekeeper. */

    ds1302_wenable();
    /* write RAM byte 0 */
    /* write something magic */
    out_byte_rtc(0xc0,MAGIC_PATTERN);

    /* read RAM byte 0 */
    if((res = in_byte_rtc(0xc1)) == MAGIC_PATTERN) {
        char buf[100];
        ds1302_wdisable();
        printk("%s: RTC found.\n", ds1302_name);
        get_rtc_status(buf);
        printk(buf);
        retval = 1;
    } else {
        printk("%s: RTC not found.\n", ds1302_name);
        retval = 0;
    }

    return retval;
}


/* Just probe for the RTC and register the device to handle the ioctl needed. */

int __init
ds1302_init(void)
{
    if (!ds1302_probe()) {
        return -1;
    }
    return 0;
}

static int __init ds1302_register(void)
{
    ds1302_init();
    if (register_chrdev(RTC_MAJOR_NR, ds1302_name, &rtc_fops)) {
        printk(KERN_INFO "%s: unable to get major %d for rtc\n",
               ds1302_name, RTC_MAJOR_NR);
        return -1;
    }
    return 0;
}

module_init(ds1302_register);