/*
   *	Real Time Clock interface for
   *		- q40 and other m68k machines,
   *		- HP PARISC machines
   *		- PowerPC machines
   *      emulate some RTC irq capabilities in software
   *
   *      Copyright (C) 1999 Richard Zidlicky
   *
   *	based on Paul Gortmaker's rtc.c device and
   *           Sam Creasey Generic rtc driver
   *
   *	This driver allows use of the real time clock (built into
   *	nearly all computers) from user space. It exports the /dev/rtc
   *	interface supporting various ioctl() and also the /proc/driver/rtc
   *	pseudo-file for status information.
   *
   *	The ioctls can be used to set the interrupt behaviour where
   *	supported.
   *
   *	The /dev/rtc interface will block on reads until an interrupt
   *	has been received. If a RTC interrupt has already happened,
   *	it will output an unsigned long and then block. The output value
   *	contains the interrupt status in the low byte and the number of
   *	interrupts since the last read in the remaining high bytes. The
   *	/dev/rtc interface can also be used with the select(2) call.
   *
   *	This program is free software; you can redistribute it and/or
   *	modify it under the terms of the GNU General Public License
   *	as published by the Free Software Foundation; either version
   *	2 of the License, or (at your option) any later version.
   *
  
   *      1.01 fix for 2.3.X                    rz@linux-m68k.org
   *      1.02 merged with code from genrtc.c   rz@linux-m68k.org
   *      1.03 make it more portable            zippel@linux-m68k.org
   *      1.04 removed useless timer code       rz@linux-m68k.org
   *      1.05 portable RTC_UIE emulation       rz@linux-m68k.org
   *      1.06 set_rtc_time can return an error trini@kernel.crashing.org
   *      1.07 ported to HP PARISC (hppa)	      Helge Deller <deller@gmx.de>
   */
  
  #define RTC_VERSION	"1.07"
  
  #include <linux/module.h>
  #include <linux/sched.h>
  #include <linux/errno.h>
  #include <linux/miscdevice.h>
  #include <linux/fcntl.h>
  
  #include <linux/rtc.h>
  #include <linux/init.h>
  #include <linux/poll.h>
  #include <linux/proc_fs.h>
  #include <linux/seq_file.h>
  #include <linux/mutex.h>
  #include <linux/workqueue.h>
  
  #include <asm/uaccess.h>
  #include <asm/rtc.h>
  
  /*
   *	We sponge a minor off of the misc major. No need slurping
   *	up another valuable major dev number for this. If you add
   *	an ioctl, make sure you don't conflict with SPARC's RTC
   *	ioctls.
   */
  
  static DEFINE_MUTEX(gen_rtc_mutex);
  static DECLARE_WAIT_QUEUE_HEAD(gen_rtc_wait);
  
  /*
   *	Bits in gen_rtc_status.
   */
  
  #define RTC_IS_OPEN		0x01	/* means /dev/rtc is in use	*/
  
  static unsigned char gen_rtc_status;	/* bitmapped status byte.	*/
  static unsigned long gen_rtc_irq_data;	/* our output to the world	*/
  
  /* months start at 0 now */
  static unsigned char days_in_mo[] =
  {31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31};
  
  static int irq_active;
  
  #ifdef CONFIG_GEN_RTC_X
  static struct work_struct genrtc_task;
  static struct timer_list timer_task;
  
  static unsigned int oldsecs;
  static int lostint;
  static unsigned long tt_exp;
  
  static void gen_rtc_timer(unsigned long data);
  
  static volatile int stask_active;              /* schedule_work */
  static volatile int ttask_active;              /* timer_task */
  static int stop_rtc_timers;                    /* don't requeue tasks */
  static DEFINE_SPINLOCK(gen_rtc_lock);
  
  static void gen_rtc_interrupt(unsigned long arg);
  
  /*
   * Routine to poll RTC seconds field for change as often as possible,
   * after first RTC_UIE use timer to reduce polling
   */
  static void genrtc_troutine(struct work_struct *work)
  {
  	unsigned int tmp = get_rtc_ss();
  	
  	if (stop_rtc_timers) {
  		stask_active = 0;
  		return;
  	}
  
  	if (oldsecs != tmp){
  		oldsecs = tmp;
  
  		timer_task.function = gen_rtc_timer;
  		timer_task.expires = jiffies + HZ - (HZ/10);
  		tt_exp=timer_task.expires;
  		ttask_active=1;
  		stask_active=0;
  		add_timer(&timer_task);
  
  		gen_rtc_interrupt(0);
  	} else if (schedule_work(&genrtc_task) == 0)
  		stask_active = 0;
  }
  
  static void gen_rtc_timer(unsigned long data)
  {
  	lostint = get_rtc_ss() - oldsecs ;
  	if (lostint<0) 
  		lostint = 60 - lostint;
  	if (time_after(jiffies, tt_exp))
  		printk(KERN_INFO "genrtc: timer task delayed by %ld jiffies
  ",
  		       jiffies-tt_exp);
  	ttask_active=0;
  	stask_active=1;
  	if ((schedule_work(&genrtc_task) == 0))
  		stask_active = 0;
  }
  
  /* 
   * call gen_rtc_interrupt function to signal an RTC_UIE,
   * arg is unused.
   * Could be invoked either from a real interrupt handler or
   * from some routine that periodically (eg 100HZ) monitors
   * whether RTC_SECS changed
   */
  static void gen_rtc_interrupt(unsigned long arg)
  {
  	/*  We store the status in the low byte and the number of
  	 *	interrupts received since the last read in the remainder
  	 *	of rtc_irq_data.  */
  
  	gen_rtc_irq_data += 0x100;
  	gen_rtc_irq_data &= ~0xff;
  	gen_rtc_irq_data |= RTC_UIE;
  
  	if (lostint){
  		printk("genrtc: system delaying clock ticks?
  ");
  		/* increment count so that userspace knows something is wrong */
  		gen_rtc_irq_data += ((lostint-1)<<8);
  		lostint = 0;
  	}
  
  	wake_up_interruptible(&gen_rtc_wait);
  }
  
  /*
   *	Now all the various file operations that we export.
   */
  static ssize_t gen_rtc_read(struct file *file, char __user *buf,
  			size_t count, loff_t *ppos)
  {
  	unsigned long data;
  	ssize_t retval;
  
  	if (count != sizeof (unsigned int) && count != sizeof (unsigned long))
  		return -EINVAL;
  
  	if (file->f_flags & O_NONBLOCK && !gen_rtc_irq_data)
  		return -EAGAIN;
  
  	retval = wait_event_interruptible(gen_rtc_wait,
  			(data = xchg(&gen_rtc_irq_data, 0)));
  	if (retval)
  		goto out;
  
  	/* first test allows optimizer to nuke this case for 32-bit machines */
  	if (sizeof (int) != sizeof (long) && count == sizeof (unsigned int)) {
  		unsigned int uidata = data;
  		retval = put_user(uidata, (unsigned int __user *)buf) ?:
  			sizeof(unsigned int);
  	}
  	else {
  		retval = put_user(data, (unsigned long __user *)buf) ?:
  			sizeof(unsigned long);
  	}
  out:
  	return retval;
  }
  
  static unsigned int gen_rtc_poll(struct file *file,
  				 struct poll_table_struct *wait)
  {
  	poll_wait(file, &gen_rtc_wait, wait);
  	if (gen_rtc_irq_data != 0)
  		return POLLIN | POLLRDNORM;
  	return 0;
  }
  
  #endif
  
  /*
   * Used to disable/enable interrupts, only RTC_UIE supported
   * We also clear out any old irq data after an ioctl() that
   * meddles with the interrupt enable/disable bits.
   */
  
  static inline void gen_clear_rtc_irq_bit(unsigned char bit)
  {
  #ifdef CONFIG_GEN_RTC_X
  	stop_rtc_timers = 1;
  	if (ttask_active){
  		del_timer_sync(&timer_task);
  		ttask_active = 0;
  	}
  	while (stask_active)
  		schedule();
  
  	spin_lock(&gen_rtc_lock);
  	irq_active = 0;
  	spin_unlock(&gen_rtc_lock);
  #endif
  }
  
  static inline int gen_set_rtc_irq_bit(unsigned char bit)
  {
  #ifdef CONFIG_GEN_RTC_X
  	spin_lock(&gen_rtc_lock);
  	if ( !irq_active ) {
  		irq_active = 1;
  		stop_rtc_timers = 0;
  		lostint = 0;
  		INIT_WORK(&genrtc_task, genrtc_troutine);
  		oldsecs = get_rtc_ss();
  		init_timer(&timer_task);
  
  		stask_active = 1;
  		if (schedule_work(&genrtc_task) == 0){
  			stask_active = 0;
  		}
  	}
  	spin_unlock(&gen_rtc_lock);
  	gen_rtc_irq_data = 0;
  	return 0;
  #else
  	return -EINVAL;
  #endif
  }
  
  static int gen_rtc_ioctl(struct file *file,
  			 unsigned int cmd, unsigned long arg)
  {
  	struct rtc_time wtime;
  	struct rtc_pll_info pll;
  	void __user *argp = (void __user *)arg;
  
  	switch (cmd) {
  
  	case RTC_PLL_GET:
  	    if (get_rtc_pll(&pll))
  	 	    return -EINVAL;
  	    else
  		    return copy_to_user(argp, &pll, sizeof pll) ? -EFAULT : 0;
  
  	case RTC_PLL_SET:
  		if (!capable(CAP_SYS_TIME))
  			return -EACCES;
  		if (copy_from_user(&pll, argp, sizeof(pll)))
  			return -EFAULT;
  	    return set_rtc_pll(&pll);
  
  	case RTC_UIE_OFF:	/* disable ints from RTC updates.	*/
  		gen_clear_rtc_irq_bit(RTC_UIE);
  		return 0;
  
  	case RTC_UIE_ON:	/* enable ints for RTC updates.	*/
  	        return gen_set_rtc_irq_bit(RTC_UIE);
  
  	case RTC_RD_TIME:	/* Read the time/date from RTC	*/
  		/* this doesn't get week-day, who cares */
  		memset(&wtime, 0, sizeof(wtime));
  		get_rtc_time(&wtime);
  
  		return copy_to_user(argp, &wtime, sizeof(wtime)) ? -EFAULT : 0;
  
  	case RTC_SET_TIME:	/* Set the RTC */
  	    {
  		int year;
  		unsigned char leap_yr;
  
  		if (!capable(CAP_SYS_TIME))
  			return -EACCES;
  
  		if (copy_from_user(&wtime, argp, sizeof(wtime)))
  			return -EFAULT;
  
  		year = wtime.tm_year + 1900;
  		leap_yr = ((!(year % 4) && (year % 100)) ||
  			   !(year % 400));
  
  		if ((wtime.tm_mon < 0 || wtime.tm_mon > 11) || (wtime.tm_mday < 1))
  			return -EINVAL;
  
  		if (wtime.tm_mday < 0 || wtime.tm_mday >
  		    (days_in_mo[wtime.tm_mon] + ((wtime.tm_mon == 1) && leap_yr)))
  			return -EINVAL;
  
  		if (wtime.tm_hour < 0 || wtime.tm_hour >= 24 ||
  		    wtime.tm_min < 0 || wtime.tm_min >= 60 ||
  		    wtime.tm_sec < 0 || wtime.tm_sec >= 60)
  			return -EINVAL;
  
  		return set_rtc_time(&wtime);
  	    }
  	}
  
  	return -EINVAL;
  }
  
  static long gen_rtc_unlocked_ioctl(struct file *file, unsigned int cmd,
  				   unsigned long arg)
  {
  	int ret;
  
  	mutex_lock(&gen_rtc_mutex);
  	ret = gen_rtc_ioctl(file, cmd, arg);
  	mutex_unlock(&gen_rtc_mutex);
  
  	return ret;
  }
  
  /*
   *	We enforce only one user at a time here with the open/close.
   *	Also clear the previous interrupt data on an open, and clean
   *	up things on a close.
   */
  
  static int gen_rtc_open(struct inode *inode, struct file *file)
  {
  	mutex_lock(&gen_rtc_mutex);
  	if (gen_rtc_status & RTC_IS_OPEN) {
  		mutex_unlock(&gen_rtc_mutex);
  		return -EBUSY;
  	}
  
  	gen_rtc_status |= RTC_IS_OPEN;
  	gen_rtc_irq_data = 0;
  	irq_active = 0;
  	mutex_unlock(&gen_rtc_mutex);
  
  	return 0;
  }
  
  static int gen_rtc_release(struct inode *inode, struct file *file)
  {
  	/*
  	 * Turn off all interrupts once the device is no longer
  	 * in use and clear the data.
  	 */
  
  	gen_clear_rtc_irq_bit(RTC_PIE|RTC_AIE|RTC_UIE);
  
  	gen_rtc_status &= ~RTC_IS_OPEN;
  	return 0;
  }
  
  
  #ifdef CONFIG_PROC_FS
  
  /*
   *	Info exported via "/proc/driver/rtc".
   */
  
  static int gen_rtc_proc_show(struct seq_file *m, void *v)
  {
  	struct rtc_time tm;
  	unsigned int flags;
  	struct rtc_pll_info pll;
  
  	flags = get_rtc_time(&tm);
  
  	seq_printf(m,
  		     "rtc_time\t: %02d:%02d:%02d
  "
  		     "rtc_date\t: %04d-%02d-%02d
  "
  		     "rtc_epoch\t: %04u
  ",
  		     tm.tm_hour, tm.tm_min, tm.tm_sec,
  		     tm.tm_year + 1900, tm.tm_mon + 1, tm.tm_mday, 1900);
  
  	tm.tm_hour = tm.tm_min = tm.tm_sec = 0;
  
  	seq_puts(m, "alarm\t\t: ");
  	if (tm.tm_hour <= 24)
  		seq_printf(m, "%02d:", tm.tm_hour);
  	else
  		seq_puts(m, "**:");
  
  	if (tm.tm_min <= 59)
  		seq_printf(m, "%02d:", tm.tm_min);
  	else
  		seq_puts(m, "**:");
  
  	if (tm.tm_sec <= 59)
  		seq_printf(m, "%02d
  ", tm.tm_sec);
  	else
  		seq_puts(m, "**
  ");
  
  	seq_printf(m,
  		     "DST_enable\t: %s
  "
  		     "BCD\t\t: %s
  "
  		     "24hr\t\t: %s
  "
  		     "square_wave\t: %s
  "
  		     "alarm_IRQ\t: %s
  "
  		     "update_IRQ\t: %s
  "
  		     "periodic_IRQ\t: %s
  "
  		     "periodic_freq\t: %ld
  "
  		     "batt_status\t: %s
  ",
  		     (flags & RTC_DST_EN) ? "yes" : "no",
  		     (flags & RTC_DM_BINARY) ? "no" : "yes",
  		     (flags & RTC_24H) ? "yes" : "no",
  		     (flags & RTC_SQWE) ? "yes" : "no",
  		     (flags & RTC_AIE) ? "yes" : "no",
  		     irq_active ? "yes" : "no",
  		     (flags & RTC_PIE) ? "yes" : "no",
  		     0L /* freq */,
  		     (flags & RTC_BATT_BAD) ? "bad" : "okay");
  	if (!get_rtc_pll(&pll))
  	    seq_printf(m,
  			 "PLL adjustment\t: %d
  "
  			 "PLL max +ve adjustment\t: %d
  "
  			 "PLL max -ve adjustment\t: %d
  "
  			 "PLL +ve adjustment factor\t: %d
  "
  			 "PLL -ve adjustment factor\t: %d
  "
  			 "PLL frequency\t: %ld
  ",
  			 pll.pll_value,
  			 pll.pll_max,
  			 pll.pll_min,
  			 pll.pll_posmult,
  			 pll.pll_negmult,
  			 pll.pll_clock);
  	return 0;
  }
  
  static int gen_rtc_proc_open(struct inode *inode, struct file *file)
  {
  	return single_open(file, gen_rtc_proc_show, NULL);
  }
  
  static const struct file_operations gen_rtc_proc_fops = {
  	.open		= gen_rtc_proc_open,
  	.read		= seq_read,
  	.llseek		= seq_lseek,
  	.release	= single_release,
  };
  
  static int __init gen_rtc_proc_init(void)
  {
  	struct proc_dir_entry *r;
  
  	r = proc_create("driver/rtc", 0, NULL, &gen_rtc_proc_fops);
  	if (!r)
  		return -ENOMEM;
  	return 0;
  }
  #else
  static inline int gen_rtc_proc_init(void) { return 0; }
  #endif /* CONFIG_PROC_FS */
  
  
  /*
   *	The various file operations we support.
   */
  
  static const struct file_operations gen_rtc_fops = {
  	.owner		= THIS_MODULE,
  #ifdef CONFIG_GEN_RTC_X
  	.read		= gen_rtc_read,
  	.poll		= gen_rtc_poll,
  #endif
  	.unlocked_ioctl	= gen_rtc_unlocked_ioctl,
  	.open		= gen_rtc_open,
  	.release	= gen_rtc_release,
  	.llseek		= noop_llseek,
  };
  
  static struct miscdevice rtc_gen_dev =
  {
  	.minor		= RTC_MINOR,
  	.name		= "rtc",
  	.fops		= &gen_rtc_fops,
  };
  
  static int __init rtc_generic_init(void)
  {
  	int retval;
  
  	printk(KERN_INFO "Generic RTC Driver v%s
  ", RTC_VERSION);
  
  	retval = misc_register(&rtc_gen_dev);
  	if (retval < 0)
  		return retval;
  
  	retval = gen_rtc_proc_init();
  	if (retval) {
  		misc_deregister(&rtc_gen_dev);
  		return retval;
  	}
  
  	return 0;
  }
  
  static void __exit rtc_generic_exit(void)
  {
  	remove_proc_entry ("driver/rtc", NULL);
  	misc_deregister(&rtc_gen_dev);
  }
  
  
  module_init(rtc_generic_init);
  module_exit(rtc_generic_exit);
  
  MODULE_AUTHOR("Richard Zidlicky");
  MODULE_LICENSE("GPL");
  MODULE_ALIAS_MISCDEV(RTC_MINOR);