/*!***************************************************************************
  *!
  *! 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/system.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
  "
  		"rtc_date\t: %04d-%02d-%02d
  ",
  		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
  ", 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.
  ", ds1302_name);
  		get_rtc_status(buf);
  		printk(buf);
  		retval = 1;
  	} else {
  		printk("%s: RTC not found.
  ", 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
  ",
  		       ds1302_name, RTC_MAJOR_NR);
  		return -1;
  	}
  	return 0;
  }
  
  module_init(ds1302_register);