drivers/char/genrtc.c

/*
 *	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/dev/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/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/workqueue.h>

#include <asm/uaccess.h>
#include <asm/system.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 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\n",
		       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?\n");
		/* 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)
{
	DECLARE_WAITQUEUE(wait, current);
	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;

	add_wait_queue(&gen_rtc_wait, &wait);
	retval = -ERESTARTSYS;

	while (1) {
		set_current_state(TASK_INTERRUPTIBLE);
		data = xchg(&gen_rtc_irq_data, 0);
		if (data)
			break;
		if (signal_pending(current))
			goto out;
		schedule();
	}

	/* 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:
	current->state = TASK_RUNNING;
	remove_wait_queue(&gen_rtc_wait, &wait);

	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 inode *inode, 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;
}

/*
 *	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)
{
	if (gen_rtc_status & RTC_IS_OPEN)
		return -EBUSY;

	gen_rtc_status |= RTC_IS_OPEN;
	gen_rtc_irq_data = 0;
	irq_active = 0;

	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/rtc".
 */

static int gen_rtc_proc_output(char *buf)
{
	char *p;
	struct rtc_time tm;
	unsigned int flags;
	struct rtc_pll_info pll;

	p = buf;

	flags = get_rtc_time(&tm);

	p += sprintf(p,
		     "rtc_time\t: %02d:%02d:%02d\n"
		     "rtc_date\t: %04d-%02d-%02d\n"
		     "rtc_epoch\t: %04u\n",
		     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;

	p += sprintf(p, "alarm\t\t: ");
	if (tm.tm_hour <= 24)
		p += sprintf(p, "%02d:", tm.tm_hour);
	else
		p += sprintf(p, "**:");

	if (tm.tm_min <= 59)
		p += sprintf(p, "%02d:", tm.tm_min);
	else
		p += sprintf(p, "**:");

	if (tm.tm_sec <= 59)
		p += sprintf(p, "%02d\n", tm.tm_sec);
	else
		p += sprintf(p, "**\n");

	p += sprintf(p,
		     "DST_enable\t: %s\n"
		     "BCD\t\t: %s\n"
		     "24hr\t\t: %s\n"
		     "square_wave\t: %s\n"
		     "alarm_IRQ\t: %s\n"
		     "update_IRQ\t: %s\n"
		     "periodic_IRQ\t: %s\n"
		     "periodic_freq\t: %ld\n"
		     "batt_status\t: %s\n",
		     (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))
	    p += sprintf(p,
			 "PLL adjustment\t: %d\n"
			 "PLL max +ve adjustment\t: %d\n"
			 "PLL max -ve adjustment\t: %d\n"
			 "PLL +ve adjustment factor\t: %d\n"
			 "PLL -ve adjustment factor\t: %d\n"
			 "PLL frequency\t: %ld\n",
			 pll.pll_value,
			 pll.pll_max,
			 pll.pll_min,
			 pll.pll_posmult,
			 pll.pll_negmult,
			 pll.pll_clock);
	return p - buf;
}

static int gen_rtc_read_proc(char *page, char **start, off_t off,
			     int count, int *eof, void *data)
{
	int len = gen_rtc_proc_output (page);
        if (len <= off+count) *eof = 1;
	*start = page + off;
	len -= off;
        if (len>count) len = count;
        if (len<0) len = 0;
	return len;
}

static int __init gen_rtc_proc_init(void)
{
	struct proc_dir_entry *r;

	r = create_proc_read_entry("driver/rtc", 0, NULL, gen_rtc_read_proc, NULL);
	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
	.ioctl		= gen_rtc_ioctl,
	.open		= gen_rtc_open,
	.release	= gen_rtc_release,
};

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\n", 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);