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ds1302.c

/*!***************************************************************************
*!
*! 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 <asm/uaccess.h>
#include <asm/system.h>
#include <asm/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 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);

      BCD_TO_BIN(rtc_tm->tm_sec);
      BCD_TO_BIN(rtc_tm->tm_min);
      BCD_TO_BIN(rtc_tm->tm_hour);
      BCD_TO_BIN(rtc_tm->tm_mday);
      BCD_TO_BIN(rtc_tm->tm_mon);
      BCD_TO_BIN(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 int
rtc_ioctl(struct inode *inode, 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));
                  get_rtc_time(&rtc_tm);
                  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) */

                  BIN_TO_BCD(sec);
                  BIN_TO_BCD(min);
                  BIN_TO_BCD(hrs);
                  BIN_TO_BCD(day);
                  BIN_TO_BCD(mon);
                  BIN_TO_BCD(yrs);

                  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);

                  /* 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;

                  tcs_val = RTC_TCR_PATTERN | (tcs_val & 0x0F);
                  ds1302_writereg(RTC_TRICKLECHARGER, tcs_val);
                  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,
      .ioctl            = rtc_ioctl,
};

/* 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);

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