Adding upstream version 4.19.249.upstream/4.19.249

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 1316 insertions, 0 deletions

diff --git a/drivers/char/rtc.c b/drivers/char/rtc.c
new file mode 100644
index 000000000..4948c8bda
--- /dev/null
+++ b/drivers/char/rtc.c
@@ -0,0 +1,1316 @@
+/*
+ *	Real Time Clock interface for Linux
+ *
+ *	Copyright (C) 1996 Paul Gortmaker
+ *
+ *	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 and
+ *	generation rate from the RTC via IRQ 8. Then the /dev/rtc
+ *	interface can be used to make use of these timer interrupts,
+ *	be they interval or alarm based.
+ *
+ *	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.
+ *
+ *	Based on other minimal char device drivers, like Alan's
+ *	watchdog, Ted's random, etc. etc.
+ *
+ *	1.07	Paul Gortmaker.
+ *	1.08	Miquel van Smoorenburg: disallow certain things on the
+ *		DEC Alpha as the CMOS clock is also used for other things.
+ *	1.09	Nikita Schmidt: epoch support and some Alpha cleanup.
+ *	1.09a	Pete Zaitcev: Sun SPARC
+ *	1.09b	Jeff Garzik: Modularize, init cleanup
+ *	1.09c	Jeff Garzik: SMP cleanup
+ *	1.10	Paul Barton-Davis: add support for async I/O
+ *	1.10a	Andrea Arcangeli: Alpha updates
+ *	1.10b	Andrew Morton: SMP lock fix
+ *	1.10c	Cesar Barros: SMP locking fixes and cleanup
+ *	1.10d	Paul Gortmaker: delete paranoia check in rtc_exit
+ *	1.10e	Maciej W. Rozycki: Handle DECstation's year weirdness.
+ *	1.11	Takashi Iwai: Kernel access functions
+ *			      rtc_register/rtc_unregister/rtc_control
+ *      1.11a   Daniele Bellucci: Audit create_proc_read_entry in rtc_init
+ *	1.12	Venkatesh Pallipadi: Hooks for emulating rtc on HPET base-timer
+ *		CONFIG_HPET_EMULATE_RTC
+ *	1.12a	Maciej W. Rozycki: Handle memory-mapped chips properly.
+ *	1.12ac	Alan Cox: Allow read access to the day of week register
+ *	1.12b	David John: Remove calls to the BKL.
+ */
+
+#define RTC_VERSION		"1.12b"
+
+/*
+ *	Note that *all* calls to CMOS_READ and CMOS_WRITE are done with
+ *	interrupts disabled. Due to the index-port/data-port (0x70/0x71)
+ *	design of the RTC, we don't want two different things trying to
+ *	get to it at once. (e.g. the periodic 11 min sync from
+ *      kernel/time/ntp.c vs. this driver.)
+ */
+
+#include <linux/interrupt.h>
+#include <linux/module.h>
+#include <linux/kernel.h>
+#include <linux/types.h>
+#include <linux/miscdevice.h>
+#include <linux/ioport.h>
+#include <linux/fcntl.h>
+#include <linux/mc146818rtc.h>
+#include <linux/init.h>
+#include <linux/poll.h>
+#include <linux/proc_fs.h>
+#include <linux/seq_file.h>
+#include <linux/spinlock.h>
+#include <linux/sched/signal.h>
+#include <linux/sysctl.h>
+#include <linux/wait.h>
+#include <linux/bcd.h>
+#include <linux/delay.h>
+#include <linux/uaccess.h>
+#include <linux/ratelimit.h>
+
+#include <asm/current.h>
+
+#ifdef CONFIG_X86
+#include <asm/hpet.h>
+#endif
+
+#ifdef CONFIG_SPARC32
+#include <linux/of.h>
+#include <linux/of_device.h>
+#include <asm/io.h>
+
+static unsigned long rtc_port;
+static int rtc_irq;
+#endif
+
+#ifdef	CONFIG_HPET_EMULATE_RTC
+#undef	RTC_IRQ
+#endif
+
+#ifdef RTC_IRQ
+static int rtc_has_irq = 1;
+#endif
+
+#ifndef CONFIG_HPET_EMULATE_RTC
+#define is_hpet_enabled()			0
+#define hpet_set_alarm_time(hrs, min, sec)	0
+#define hpet_set_periodic_freq(arg)		0
+#define hpet_mask_rtc_irq_bit(arg)		0
+#define hpet_set_rtc_irq_bit(arg)		0
+#define hpet_rtc_timer_init()			do { } while (0)
+#define hpet_rtc_dropped_irq()			0
+#define hpet_register_irq_handler(h)		({ 0; })
+#define hpet_unregister_irq_handler(h)		({ 0; })
+#ifdef RTC_IRQ
+static irqreturn_t hpet_rtc_interrupt(int irq, void *dev_id)
+{
+	return 0;
+}
+#endif
+#endif
+
+/*
+ *	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 struct fasync_struct *rtc_async_queue;
+
+static DECLARE_WAIT_QUEUE_HEAD(rtc_wait);
+
+#ifdef RTC_IRQ
+static void rtc_dropped_irq(struct timer_list *unused);
+
+static DEFINE_TIMER(rtc_irq_timer, rtc_dropped_irq);
+#endif
+
+static ssize_t rtc_read(struct file *file, char __user *buf,
+			size_t count, loff_t *ppos);
+
+static long rtc_ioctl(struct file *file, unsigned int cmd, unsigned long arg);
+static void rtc_get_rtc_time(struct rtc_time *rtc_tm);
+
+#ifdef RTC_IRQ
+static __poll_t rtc_poll(struct file *file, poll_table *wait);
+#endif
+
+static void get_rtc_alm_time(struct rtc_time *alm_tm);
+#ifdef RTC_IRQ
+static void set_rtc_irq_bit_locked(unsigned char bit);
+static void mask_rtc_irq_bit_locked(unsigned char bit);
+
+static inline void set_rtc_irq_bit(unsigned char bit)
+{
+	spin_lock_irq(&rtc_lock);
+	set_rtc_irq_bit_locked(bit);
+	spin_unlock_irq(&rtc_lock);
+}
+
+static void mask_rtc_irq_bit(unsigned char bit)
+{
+	spin_lock_irq(&rtc_lock);
+	mask_rtc_irq_bit_locked(bit);
+	spin_unlock_irq(&rtc_lock);
+}
+#endif
+
+#ifdef CONFIG_PROC_FS
+static int rtc_proc_show(struct seq_file *seq, void *v);
+#endif
+
+/*
+ *	Bits in rtc_status. (6 bits of room for future expansion)
+ */
+
+#define RTC_IS_OPEN		0x01	/* means /dev/rtc is in use	*/
+#define RTC_TIMER_ON		0x02	/* missed irq timer active	*/
+
+/*
+ * rtc_status is never changed by rtc_interrupt, and ioctl/open/close is
+ * protected by the spin lock rtc_lock. However, ioctl can still disable the
+ * timer in rtc_status and then with del_timer after the interrupt has read
+ * rtc_status but before mod_timer is called, which would then reenable the
+ * timer (but you would need to have an awful timing before you'd trip on it)
+ */
+static unsigned long rtc_status;	/* bitmapped status byte.	*/
+static unsigned long rtc_freq;		/* Current periodic IRQ rate	*/
+static unsigned long rtc_irq_data;	/* our output to the world	*/
+static unsigned long rtc_max_user_freq = 64; /* > this, need CAP_SYS_RESOURCE */
+
+/*
+ *	If this driver ever becomes modularised, it will be really nice
+ *	to make the epoch retain its value across module reload...
+ */
+
+static unsigned long epoch = 1900;	/* year corresponding to 0x00	*/
+
+static const unsigned char days_in_mo[] =
+{0, 31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31};
+
+/*
+ * Returns true if a clock update is in progress
+ */
+static inline unsigned char rtc_is_updating(void)
+{
+	unsigned long flags;
+	unsigned char uip;
+
+	spin_lock_irqsave(&rtc_lock, flags);
+	uip = (CMOS_READ(RTC_FREQ_SELECT) & RTC_UIP);
+	spin_unlock_irqrestore(&rtc_lock, flags);
+	return uip;
+}
+
+#ifdef RTC_IRQ
+/*
+ *	A very tiny interrupt handler. It runs with interrupts disabled,
+ *	but there is possibility of conflicting with the set_rtc_mmss()
+ *	call (the rtc irq and the timer irq can easily run at the same
+ *	time in two different CPUs). So we need to serialize
+ *	accesses to the chip with the rtc_lock spinlock that each
+ *	architecture should implement in the timer code.
+ *	(See ./arch/XXXX/kernel/time.c for the set_rtc_mmss() function.)
+ */
+
+static irqreturn_t rtc_interrupt(int irq, void *dev_id)
+{
+	/*
+	 *	Can be an alarm interrupt, update complete interrupt,
+	 *	or a periodic interrupt. 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.
+	 */
+
+	spin_lock(&rtc_lock);
+	rtc_irq_data += 0x100;
+	rtc_irq_data &= ~0xff;
+	if (is_hpet_enabled()) {
+		/*
+		 * In this case it is HPET RTC interrupt handler
+		 * calling us, with the interrupt information
+		 * passed as arg1, instead of irq.
+		 */
+		rtc_irq_data |= (unsigned long)irq & 0xF0;
+	} else {
+		rtc_irq_data |= (CMOS_READ(RTC_INTR_FLAGS) & 0xF0);
+	}
+
+	if (rtc_status & RTC_TIMER_ON)
+		mod_timer(&rtc_irq_timer, jiffies + HZ/rtc_freq + 2*HZ/100);
+
+	spin_unlock(&rtc_lock);
+
+	wake_up_interruptible(&rtc_wait);
+
+	kill_fasync(&rtc_async_queue, SIGIO, POLL_IN);
+
+	return IRQ_HANDLED;
+}
+#endif
+
+/*
+ * sysctl-tuning infrastructure.
+ */
+static struct ctl_table rtc_table[] = {
+	{
+		.procname	= "max-user-freq",
+		.data		= &rtc_max_user_freq,
+		.maxlen		= sizeof(int),
+		.mode		= 0644,
+		.proc_handler	= proc_dointvec,
+	},
+	{ }
+};
+
+static struct ctl_table rtc_root[] = {
+	{
+		.procname	= "rtc",
+		.mode		= 0555,
+		.child		= rtc_table,
+	},
+	{ }
+};
+
+static struct ctl_table dev_root[] = {
+	{
+		.procname	= "dev",
+		.mode		= 0555,
+		.child		= rtc_root,
+	},
+	{ }
+};
+
+static struct ctl_table_header *sysctl_header;
+
+static int __init init_sysctl(void)
+{
+    sysctl_header = register_sysctl_table(dev_root);
+    return 0;
+}
+
+static void __exit cleanup_sysctl(void)
+{
+    unregister_sysctl_table(sysctl_header);
+}
+
+/*
+ *	Now all the various file operations that we export.
+ */
+
+static ssize_t rtc_read(struct file *file, char __user *buf,
+			size_t count, loff_t *ppos)
+{
+#ifndef RTC_IRQ
+	return -EIO;
+#else
+	DECLARE_WAITQUEUE(wait, current);
+	unsigned long data;
+	ssize_t retval;
+
+	if (rtc_has_irq == 0)
+		return -EIO;
+
+	/*
+	 * Historically this function used to assume that sizeof(unsigned long)
+	 * is the same in userspace and kernelspace.  This lead to problems
+	 * for configurations with multiple ABIs such a the MIPS o32 and 64
+	 * ABIs supported on the same kernel.  So now we support read of both
+	 * 4 and 8 bytes and assume that's the sizeof(unsigned long) in the
+	 * userspace ABI.
+	 */
+	if (count != sizeof(unsigned int) && count !=  sizeof(unsigned long))
+		return -EINVAL;
+
+	add_wait_queue(&rtc_wait, &wait);
+
+	do {
+		/* First make it right. Then make it fast. Putting this whole
+		 * block within the parentheses of a while would be too
+		 * confusing. And no, xchg() is not the answer. */
+
+		__set_current_state(TASK_INTERRUPTIBLE);
+
+		spin_lock_irq(&rtc_lock);
+		data = rtc_irq_data;
+		rtc_irq_data = 0;
+		spin_unlock_irq(&rtc_lock);
+
+		if (data != 0)
+			break;
+
+		if (file->f_flags & O_NONBLOCK) {
+			retval = -EAGAIN;
+			goto out;
+		}
+		if (signal_pending(current)) {
+			retval = -ERESTARTSYS;
+			goto out;
+		}
+		schedule();
+	} while (1);
+
+	if (count == sizeof(unsigned int)) {
+		retval = put_user(data,
+				  (unsigned int __user *)buf) ?: sizeof(int);
+	} else {
+		retval = put_user(data,
+				  (unsigned long __user *)buf) ?: sizeof(long);
+	}
+	if (!retval)
+		retval = count;
+ out:
+	__set_current_state(TASK_RUNNING);
+	remove_wait_queue(&rtc_wait, &wait);
+
+	return retval;
+#endif
+}
+
+static int rtc_do_ioctl(unsigned int cmd, unsigned long arg, int kernel)
+{
+	struct rtc_time wtime;
+
+#ifdef RTC_IRQ
+	if (rtc_has_irq == 0) {
+		switch (cmd) {
+		case RTC_AIE_OFF:
+		case RTC_AIE_ON:
+		case RTC_PIE_OFF:
+		case RTC_PIE_ON:
+		case RTC_UIE_OFF:
+		case RTC_UIE_ON:
+		case RTC_IRQP_READ:
+		case RTC_IRQP_SET:
+			return -EINVAL;
+		}
+	}
+#endif
+
+	switch (cmd) {
+#ifdef RTC_IRQ
+	case RTC_AIE_OFF:	/* Mask alarm int. enab. bit	*/
+	{
+		mask_rtc_irq_bit(RTC_AIE);
+		return 0;
+	}
+	case RTC_AIE_ON:	/* Allow alarm interrupts.	*/
+	{
+		set_rtc_irq_bit(RTC_AIE);
+		return 0;
+	}
+	case RTC_PIE_OFF:	/* Mask periodic int. enab. bit	*/
+	{
+		/* can be called from isr via rtc_control() */
+		unsigned long flags;
+
+		spin_lock_irqsave(&rtc_lock, flags);
+		mask_rtc_irq_bit_locked(RTC_PIE);
+		if (rtc_status & RTC_TIMER_ON) {
+			rtc_status &= ~RTC_TIMER_ON;
+			del_timer(&rtc_irq_timer);
+		}
+		spin_unlock_irqrestore(&rtc_lock, flags);
+
+		return 0;
+	}
+	case RTC_PIE_ON:	/* Allow periodic ints		*/
+	{
+		/* can be called from isr via rtc_control() */
+		unsigned long flags;
+
+		/*
+		 * We don't really want Joe User enabling more
+		 * than 64Hz of interrupts on a multi-user machine.
+		 */
+		if (!kernel && (rtc_freq > rtc_max_user_freq) &&
+						(!capable(CAP_SYS_RESOURCE)))
+			return -EACCES;
+
+		spin_lock_irqsave(&rtc_lock, flags);
+		if (!(rtc_status & RTC_TIMER_ON)) {
+			mod_timer(&rtc_irq_timer, jiffies + HZ/rtc_freq +
+					2*HZ/100);
+			rtc_status |= RTC_TIMER_ON;
+		}
+		set_rtc_irq_bit_locked(RTC_PIE);
+		spin_unlock_irqrestore(&rtc_lock, flags);
+
+		return 0;
+	}
+	case RTC_UIE_OFF:	/* Mask ints from RTC updates.	*/
+	{
+		mask_rtc_irq_bit(RTC_UIE);
+		return 0;
+	}
+	case RTC_UIE_ON:	/* Allow ints for RTC updates.	*/
+	{
+		set_rtc_irq_bit(RTC_UIE);
+		return 0;
+	}
+#endif
+	case RTC_ALM_READ:	/* Read the present alarm time */
+	{
+		/*
+		 * This returns a struct rtc_time. Reading >= 0xc0
+		 * means "don't care" or "match all". Only the tm_hour,
+		 * tm_min, and tm_sec values are filled in.
+		 */
+		memset(&wtime, 0, sizeof(struct rtc_time));
+		get_rtc_alm_time(&wtime);
+		break;
+	}
+	case RTC_ALM_SET:	/* Store a time into the alarm */
+	{
+		/*
+		 * This expects a struct rtc_time. Writing 0xff means
+		 * "don't care" or "match all". Only the tm_hour,
+		 * tm_min and tm_sec are used.
+		 */
+		unsigned char hrs, min, sec;
+		struct rtc_time alm_tm;
+
+		if (copy_from_user(&alm_tm, (struct rtc_time __user *)arg,
+				   sizeof(struct rtc_time)))
+			return -EFAULT;
+
+		hrs = alm_tm.tm_hour;
+		min = alm_tm.tm_min;
+		sec = alm_tm.tm_sec;
+
+		spin_lock_irq(&rtc_lock);
+		if (hpet_set_alarm_time(hrs, min, sec)) {
+			/*
+			 * Fallthru and set alarm time in CMOS too,
+			 * so that we will get proper value in RTC_ALM_READ
+			 */
+		}
+		if (!(CMOS_READ(RTC_CONTROL) & RTC_DM_BINARY) ||
+							RTC_ALWAYS_BCD) {
+			if (sec < 60)
+				sec = bin2bcd(sec);
+			else
+				sec = 0xff;
+
+			if (min < 60)
+				min = bin2bcd(min);
+			else
+				min = 0xff;
+
+			if (hrs < 24)
+				hrs = bin2bcd(hrs);
+			else
+				hrs = 0xff;
+		}
+		CMOS_WRITE(hrs, RTC_HOURS_ALARM);
+		CMOS_WRITE(min, RTC_MINUTES_ALARM);
+		CMOS_WRITE(sec, RTC_SECONDS_ALARM);
+		spin_unlock_irq(&rtc_lock);
+
+		return 0;
+	}
+	case RTC_RD_TIME:	/* Read the time/date from RTC	*/
+	{
+		memset(&wtime, 0, sizeof(struct rtc_time));
+		rtc_get_rtc_time(&wtime);
+		break;
+	}
+	case RTC_SET_TIME:	/* Set the RTC */
+	{
+		struct rtc_time rtc_tm;
+		unsigned char mon, day, hrs, min, sec, leap_yr;
+		unsigned char save_control, save_freq_select;
+		unsigned int yrs;
+#ifdef CONFIG_MACH_DECSTATION
+		unsigned int real_yrs;
+#endif
+
+		if (!capable(CAP_SYS_TIME))
+			return -EACCES;
+
+		if (copy_from_user(&rtc_tm, (struct rtc_time __user *)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)
+			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;
+
+		yrs -= epoch;
+		if (yrs > 255)		/* They are unsigned */
+			return -EINVAL;
+
+		spin_lock_irq(&rtc_lock);
+#ifdef CONFIG_MACH_DECSTATION
+		real_yrs = yrs;
+		yrs = 72;
+
+		/*
+		 * We want to keep the year set to 73 until March
+		 * for non-leap years, so that Feb, 29th is handled
+		 * correctly.
+		 */
+		if (!leap_yr && mon < 3) {
+			real_yrs--;
+			yrs = 73;
+		}
+#endif
+		/* These limits and adjustments are independent of
+		 * whether the chip is in binary mode or not.
+		 */
+		if (yrs > 169) {
+			spin_unlock_irq(&rtc_lock);
+			return -EINVAL;
+		}
+		if (yrs >= 100)
+			yrs -= 100;
+
+		if (!(CMOS_READ(RTC_CONTROL) & RTC_DM_BINARY)
+		    || RTC_ALWAYS_BCD) {
+			sec = bin2bcd(sec);
+			min = bin2bcd(min);
+			hrs = bin2bcd(hrs);
+			day = bin2bcd(day);
+			mon = bin2bcd(mon);
+			yrs = bin2bcd(yrs);
+		}
+
+		save_control = CMOS_READ(RTC_CONTROL);
+		CMOS_WRITE((save_control|RTC_SET), RTC_CONTROL);
+		save_freq_select = CMOS_READ(RTC_FREQ_SELECT);
+		CMOS_WRITE((save_freq_select|RTC_DIV_RESET2), RTC_FREQ_SELECT);
+
+#ifdef CONFIG_MACH_DECSTATION
+		CMOS_WRITE(real_yrs, RTC_DEC_YEAR);
+#endif
+		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);
+
+		CMOS_WRITE(save_control, RTC_CONTROL);
+		CMOS_WRITE(save_freq_select, RTC_FREQ_SELECT);
+
+		spin_unlock_irq(&rtc_lock);
+		return 0;
+	}
+#ifdef RTC_IRQ
+	case RTC_IRQP_READ:	/* Read the periodic IRQ rate.	*/
+	{
+		return put_user(rtc_freq, (unsigned long __user *)arg);
+	}
+	case RTC_IRQP_SET:	/* Set periodic IRQ rate.	*/
+	{
+		int tmp = 0;
+		unsigned char val;
+		/* can be called from isr via rtc_control() */
+		unsigned long flags;
+
+		/*
+		 * The max we can do is 8192Hz.
+		 */
+		if ((arg < 2) || (arg > 8192))
+			return -EINVAL;
+		/*
+		 * We don't really want Joe User generating more
+		 * than 64Hz of interrupts on a multi-user machine.
+		 */
+		if (!kernel && (arg > rtc_max_user_freq) &&
+					!capable(CAP_SYS_RESOURCE))
+			return -EACCES;
+
+		while (arg > (1<<tmp))
+			tmp++;
+
+		/*
+		 * Check that the input was really a power of 2.
+		 */
+		if (arg != (1<<tmp))
+			return -EINVAL;
+
+		rtc_freq = arg;
+
+		spin_lock_irqsave(&rtc_lock, flags);
+		if (hpet_set_periodic_freq(arg)) {
+			spin_unlock_irqrestore(&rtc_lock, flags);
+			return 0;
+		}
+
+		val = CMOS_READ(RTC_FREQ_SELECT) & 0xf0;
+		val |= (16 - tmp);
+		CMOS_WRITE(val, RTC_FREQ_SELECT);
+		spin_unlock_irqrestore(&rtc_lock, flags);
+		return 0;
+	}
+#endif
+	case RTC_EPOCH_READ:	/* Read the epoch.	*/
+	{
+		return put_user(epoch, (unsigned long __user *)arg);
+	}
+	case RTC_EPOCH_SET:	/* Set the epoch.	*/
+	{
+		/*
+		 * There were no RTC clocks before 1900.
+		 */
+		if (arg < 1900)
+			return -EINVAL;
+
+		if (!capable(CAP_SYS_TIME))
+			return -EACCES;
+
+		epoch = arg;
+		return 0;
+	}
+	default:
+		return -ENOTTY;
+	}
+	return copy_to_user((void __user *)arg,
+			    &wtime, sizeof wtime) ? -EFAULT : 0;
+}
+
+static long rtc_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
+{
+	long ret;
+	ret = rtc_do_ioctl(cmd, arg, 0);
+	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 rtc_open(struct inode *inode, struct file *file)
+{
+	spin_lock_irq(&rtc_lock);
+
+	if (rtc_status & RTC_IS_OPEN)
+		goto out_busy;
+
+	rtc_status |= RTC_IS_OPEN;
+
+	rtc_irq_data = 0;
+	spin_unlock_irq(&rtc_lock);
+	return 0;
+
+out_busy:
+	spin_unlock_irq(&rtc_lock);
+	return -EBUSY;
+}
+
+static int rtc_fasync(int fd, struct file *filp, int on)
+{
+	return fasync_helper(fd, filp, on, &rtc_async_queue);
+}
+
+static int rtc_release(struct inode *inode, struct file *file)
+{
+#ifdef RTC_IRQ
+	unsigned char tmp;
+
+	if (rtc_has_irq == 0)
+		goto no_irq;
+
+	/*
+	 * Turn off all interrupts once the device is no longer
+	 * in use, and clear the data.
+	 */
+
+	spin_lock_irq(&rtc_lock);
+	if (!hpet_mask_rtc_irq_bit(RTC_PIE | RTC_AIE | RTC_UIE)) {
+		tmp = CMOS_READ(RTC_CONTROL);
+		tmp &=  ~RTC_PIE;
+		tmp &=  ~RTC_AIE;
+		tmp &=  ~RTC_UIE;
+		CMOS_WRITE(tmp, RTC_CONTROL);
+		CMOS_READ(RTC_INTR_FLAGS);
+	}
+	if (rtc_status & RTC_TIMER_ON) {
+		rtc_status &= ~RTC_TIMER_ON;
+		del_timer(&rtc_irq_timer);
+	}
+	spin_unlock_irq(&rtc_lock);
+
+no_irq:
+#endif
+
+	spin_lock_irq(&rtc_lock);
+	rtc_irq_data = 0;
+	rtc_status &= ~RTC_IS_OPEN;
+	spin_unlock_irq(&rtc_lock);
+
+	return 0;
+}
+
+#ifdef RTC_IRQ
+static __poll_t rtc_poll(struct file *file, poll_table *wait)
+{
+	unsigned long l;
+
+	if (rtc_has_irq == 0)
+		return 0;
+
+	poll_wait(file, &rtc_wait, wait);
+
+	spin_lock_irq(&rtc_lock);
+	l = rtc_irq_data;
+	spin_unlock_irq(&rtc_lock);
+
+	if (l != 0)
+		return EPOLLIN | EPOLLRDNORM;
+	return 0;
+}
+#endif
+
+/*
+ *	The various file operations we support.
+ */
+
+static const struct file_operations rtc_fops = {
+	.owner		= THIS_MODULE,
+	.llseek		= no_llseek,
+	.read		= rtc_read,
+#ifdef RTC_IRQ
+	.poll		= rtc_poll,
+#endif
+	.unlocked_ioctl	= rtc_ioctl,
+	.open		= rtc_open,
+	.release	= rtc_release,
+	.fasync		= rtc_fasync,
+};
+
+static struct miscdevice rtc_dev = {
+	.minor		= RTC_MINOR,
+	.name		= "rtc",
+	.fops		= &rtc_fops,
+};
+
+static resource_size_t rtc_size;
+
+static struct resource * __init rtc_request_region(resource_size_t size)
+{
+	struct resource *r;
+
+	if (RTC_IOMAPPED)
+		r = request_region(RTC_PORT(0), size, "rtc");
+	else
+		r = request_mem_region(RTC_PORT(0), size, "rtc");
+
+	if (r)
+		rtc_size = size;
+
+	return r;
+}
+
+static void rtc_release_region(void)
+{
+	if (RTC_IOMAPPED)
+		release_region(RTC_PORT(0), rtc_size);
+	else
+		release_mem_region(RTC_PORT(0), rtc_size);
+}
+
+static int __init rtc_init(void)
+{
+#ifdef CONFIG_PROC_FS
+	struct proc_dir_entry *ent;
+#endif
+#if defined(__alpha__) || defined(__mips__)
+	unsigned int year, ctrl;
+	char *guess = NULL;
+#endif
+#ifdef CONFIG_SPARC32
+	struct device_node *ebus_dp;
+	struct platform_device *op;
+#else
+	void *r;
+#ifdef RTC_IRQ
+	irq_handler_t rtc_int_handler_ptr;
+#endif
+#endif
+
+#ifdef CONFIG_SPARC32
+	for_each_node_by_name(ebus_dp, "ebus") {
+		struct device_node *dp;
+		for (dp = ebus_dp; dp; dp = dp->sibling) {
+			if (!strcmp(dp->name, "rtc")) {
+				op = of_find_device_by_node(dp);
+				if (op) {
+					rtc_port = op->resource[0].start;
+					rtc_irq = op->irqs[0];
+					goto found;
+				}
+			}
+		}
+	}
+	rtc_has_irq = 0;
+	printk(KERN_ERR "rtc_init: no PC rtc found\n");
+	return -EIO;
+
+found:
+	if (!rtc_irq) {
+		rtc_has_irq = 0;
+		goto no_irq;
+	}
+
+	/*
+	 * XXX Interrupt pin #7 in Espresso is shared between RTC and
+	 * PCI Slot 2 INTA# (and some INTx# in Slot 1).
+	 */
+	if (request_irq(rtc_irq, rtc_interrupt, IRQF_SHARED, "rtc",
+			(void *)&rtc_port)) {
+		rtc_has_irq = 0;
+		printk(KERN_ERR "rtc: cannot register IRQ %d\n", rtc_irq);
+		return -EIO;
+	}
+no_irq:
+#else
+	r = rtc_request_region(RTC_IO_EXTENT);
+
+	/*
+	 * If we've already requested a smaller range (for example, because
+	 * PNPBIOS or ACPI told us how the device is configured), the request
+	 * above might fail because it's too big.
+	 *
+	 * If so, request just the range we actually use.
+	 */
+	if (!r)
+		r = rtc_request_region(RTC_IO_EXTENT_USED);
+	if (!r) {
+#ifdef RTC_IRQ
+		rtc_has_irq = 0;
+#endif
+		printk(KERN_ERR "rtc: I/O resource %lx is not free.\n",
+		       (long)(RTC_PORT(0)));
+		return -EIO;
+	}
+
+#ifdef RTC_IRQ
+	if (is_hpet_enabled()) {
+		int err;
+
+		rtc_int_handler_ptr = hpet_rtc_interrupt;
+		err = hpet_register_irq_handler(rtc_interrupt);
+		if (err != 0) {
+			printk(KERN_WARNING "hpet_register_irq_handler failed "
+					"in rtc_init().");
+			return err;
+		}
+	} else {
+		rtc_int_handler_ptr = rtc_interrupt;
+	}
+
+	if (request_irq(RTC_IRQ, rtc_int_handler_ptr, 0, "rtc", NULL)) {
+		/* Yeah right, seeing as irq 8 doesn't even hit the bus. */
+		rtc_has_irq = 0;
+		printk(KERN_ERR "rtc: IRQ %d is not free.\n", RTC_IRQ);
+		rtc_release_region();
+
+		return -EIO;
+	}
+	hpet_rtc_timer_init();
+
+#endif
+
+#endif /* CONFIG_SPARC32 vs. others */
+
+	if (misc_register(&rtc_dev)) {
+#ifdef RTC_IRQ
+		free_irq(RTC_IRQ, NULL);
+		hpet_unregister_irq_handler(rtc_interrupt);
+		rtc_has_irq = 0;
+#endif
+		rtc_release_region();
+		return -ENODEV;
+	}
+
+#ifdef CONFIG_PROC_FS
+	ent = proc_create_single("driver/rtc", 0, NULL, rtc_proc_show);
+	if (!ent)
+		printk(KERN_WARNING "rtc: Failed to register with procfs.\n");
+#endif
+
+#if defined(__alpha__) || defined(__mips__)
+	rtc_freq = HZ;
+
+	/* Each operating system on an Alpha uses its own epoch.
+	   Let's try to guess which one we are using now. */
+
+	if (rtc_is_updating() != 0)
+		msleep(20);
+
+	spin_lock_irq(&rtc_lock);
+	year = CMOS_READ(RTC_YEAR);
+	ctrl = CMOS_READ(RTC_CONTROL);
+	spin_unlock_irq(&rtc_lock);
+
+	if (!(ctrl & RTC_DM_BINARY) || RTC_ALWAYS_BCD)
+		year = bcd2bin(year);       /* This should never happen... */
+
+	if (year < 20) {
+		epoch = 2000;
+		guess = "SRM (post-2000)";
+	} else if (year >= 20 && year < 48) {
+		epoch = 1980;
+		guess = "ARC console";
+	} else if (year >= 48 && year < 72) {
+		epoch = 1952;
+		guess = "Digital UNIX";
+#if defined(__mips__)
+	} else if (year >= 72 && year < 74) {
+		epoch = 2000;
+		guess = "Digital DECstation";
+#else
+	} else if (year >= 70) {
+		epoch = 1900;
+		guess = "Standard PC (1900)";
+#endif
+	}
+	if (guess)
+		printk(KERN_INFO "rtc: %s epoch (%lu) detected\n",
+			guess, epoch);
+#endif
+#ifdef RTC_IRQ
+	if (rtc_has_irq == 0)
+		goto no_irq2;
+
+	spin_lock_irq(&rtc_lock);
+	rtc_freq = 1024;
+	if (!hpet_set_periodic_freq(rtc_freq)) {
+		/*
+		 * Initialize periodic frequency to CMOS reset default,
+		 * which is 1024Hz
+		 */
+		CMOS_WRITE(((CMOS_READ(RTC_FREQ_SELECT) & 0xF0) | 0x06),
+			   RTC_FREQ_SELECT);
+	}
+	spin_unlock_irq(&rtc_lock);
+no_irq2:
+#endif
+
+	(void) init_sysctl();
+
+	printk(KERN_INFO "Real Time Clock Driver v" RTC_VERSION "\n");
+
+	return 0;
+}
+
+static void __exit rtc_exit(void)
+{
+	cleanup_sysctl();
+	remove_proc_entry("driver/rtc", NULL);
+	misc_deregister(&rtc_dev);
+
+#ifdef CONFIG_SPARC32
+	if (rtc_has_irq)
+		free_irq(rtc_irq, &rtc_port);
+#else
+	rtc_release_region();
+#ifdef RTC_IRQ
+	if (rtc_has_irq) {
+		free_irq(RTC_IRQ, NULL);
+		hpet_unregister_irq_handler(hpet_rtc_interrupt);
+	}
+#endif
+#endif /* CONFIG_SPARC32 */
+}
+
+module_init(rtc_init);
+module_exit(rtc_exit);
+
+#ifdef RTC_IRQ
+/*
+ *	At IRQ rates >= 4096Hz, an interrupt may get lost altogether.
+ *	(usually during an IDE disk interrupt, with IRQ unmasking off)
+ *	Since the interrupt handler doesn't get called, the IRQ status
+ *	byte doesn't get read, and the RTC stops generating interrupts.
+ *	A timer is set, and will call this function if/when that happens.
+ *	To get it out of this stalled state, we just read the status.
+ *	At least a jiffy of interrupts (rtc_freq/HZ) will have been lost.
+ *	(You *really* shouldn't be trying to use a non-realtime system
+ *	for something that requires a steady > 1KHz signal anyways.)
+ */
+
+static void rtc_dropped_irq(struct timer_list *unused)
+{
+	unsigned long freq;
+
+	spin_lock_irq(&rtc_lock);
+
+	if (hpet_rtc_dropped_irq()) {
+		spin_unlock_irq(&rtc_lock);
+		return;
+	}
+
+	/* Just in case someone disabled the timer from behind our back... */
+	if (rtc_status & RTC_TIMER_ON)
+		mod_timer(&rtc_irq_timer, jiffies + HZ/rtc_freq + 2*HZ/100);
+
+	rtc_irq_data += ((rtc_freq/HZ)<<8);
+	rtc_irq_data &= ~0xff;
+	rtc_irq_data |= (CMOS_READ(RTC_INTR_FLAGS) & 0xF0);	/* restart */
+
+	freq = rtc_freq;
+
+	spin_unlock_irq(&rtc_lock);
+
+	printk_ratelimited(KERN_WARNING "rtc: lost some interrupts at %ldHz.\n",
+			   freq);
+
+	/* Now we have new data */
+	wake_up_interruptible(&rtc_wait);
+
+	kill_fasync(&rtc_async_queue, SIGIO, POLL_IN);
+}
+#endif
+
+#ifdef CONFIG_PROC_FS
+/*
+ *	Info exported via "/proc/driver/rtc".
+ */
+
+static int rtc_proc_show(struct seq_file *seq, void *v)
+{
+#define YN(bit) ((ctrl & bit) ? "yes" : "no")
+#define NY(bit) ((ctrl & bit) ? "no" : "yes")
+	struct rtc_time tm;
+	unsigned char batt, ctrl;
+	unsigned long freq;
+
+	spin_lock_irq(&rtc_lock);
+	batt = CMOS_READ(RTC_VALID) & RTC_VRT;
+	ctrl = CMOS_READ(RTC_CONTROL);
+	freq = rtc_freq;
+	spin_unlock_irq(&rtc_lock);
+
+
+	rtc_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.
+	 */
+	seq_printf(seq,
+		   "rtc_time\t: %02d:%02d:%02d\n"
+		   "rtc_date\t: %04d-%02d-%02d\n"
+		   "rtc_epoch\t: %04lu\n",
+		   tm.tm_hour, tm.tm_min, tm.tm_sec,
+		   tm.tm_year + 1900, tm.tm_mon + 1, tm.tm_mday, epoch);
+
+	get_rtc_alm_time(&tm);
+
+	/*
+	 * We implicitly assume 24hr mode here. Alarm values >= 0xc0 will
+	 * match any value for that particular field. Values that are
+	 * greater than a valid time, but less than 0xc0 shouldn't appear.
+	 */
+	seq_puts(seq, "alarm\t\t: ");
+	if (tm.tm_hour <= 24)
+		seq_printf(seq, "%02d:", tm.tm_hour);
+	else
+		seq_puts(seq, "**:");
+
+	if (tm.tm_min <= 59)
+		seq_printf(seq, "%02d:", tm.tm_min);
+	else
+		seq_puts(seq, "**:");
+
+	if (tm.tm_sec <= 59)
+		seq_printf(seq, "%02d\n", tm.tm_sec);
+	else
+		seq_puts(seq, "**\n");
+
+	seq_printf(seq,
+		   "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",
+		   YN(RTC_DST_EN),
+		   NY(RTC_DM_BINARY),
+		   YN(RTC_24H),
+		   YN(RTC_SQWE),
+		   YN(RTC_AIE),
+		   YN(RTC_UIE),
+		   YN(RTC_PIE),
+		   freq,
+		   batt ? "okay" : "dead");
+
+	return  0;
+#undef YN
+#undef NY
+}
+#endif
+
+static void rtc_get_rtc_time(struct rtc_time *rtc_tm)
+{
+	unsigned long uip_watchdog = jiffies, flags;
+	unsigned char ctrl;
+#ifdef CONFIG_MACH_DECSTATION
+	unsigned int real_year;
+#endif
+
+	/*
+	 * read RTC once any update in progress is done. The update
+	 * can take just over 2ms. We wait 20ms. There is no need to
+	 * to poll-wait (up to 1s - eeccch) for the falling edge of RTC_UIP.
+	 * If you need to know *exactly* when a second has started, enable
+	 * periodic update complete interrupts, (via ioctl) and then
+	 * immediately read /dev/rtc which will block until you get the IRQ.
+	 * Once the read clears, read the RTC time (again via ioctl). Easy.
+	 */
+
+	while (rtc_is_updating() != 0 &&
+	       time_before(jiffies, uip_watchdog + 2*HZ/100))
+		cpu_relax();
+
+	/*
+	 * Only the values that we read from the RTC are set. We leave
+	 * tm_wday, tm_yday and tm_isdst untouched. Note that while the
+	 * RTC has RTC_DAY_OF_WEEK, we should usually ignore it, as it is
+	 * only updated by the RTC when initially set to a non-zero value.
+	 */
+	spin_lock_irqsave(&rtc_lock, 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);
+	/* Only set from 2.6.16 onwards */
+	rtc_tm->tm_wday = CMOS_READ(RTC_DAY_OF_WEEK);
+
+#ifdef CONFIG_MACH_DECSTATION
+	real_year = CMOS_READ(RTC_DEC_YEAR);
+#endif
+	ctrl = CMOS_READ(RTC_CONTROL);
+	spin_unlock_irqrestore(&rtc_lock, flags);
+
+	if (!(ctrl & RTC_DM_BINARY) || RTC_ALWAYS_BCD) {
+		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);
+		rtc_tm->tm_wday = bcd2bin(rtc_tm->tm_wday);
+	}
+
+#ifdef CONFIG_MACH_DECSTATION
+	rtc_tm->tm_year += real_year - 72;
+#endif
+
+	/*
+	 * Account for differences between how the RTC uses the values
+	 * and how they are defined in a struct rtc_time;
+	 */
+	rtc_tm->tm_year += epoch - 1900;
+	if (rtc_tm->tm_year <= 69)
+		rtc_tm->tm_year += 100;
+
+	rtc_tm->tm_mon--;
+}
+
+static void get_rtc_alm_time(struct rtc_time *alm_tm)
+{
+	unsigned char ctrl;
+
+	/*
+	 * Only the values that we read from the RTC are set. That
+	 * means only tm_hour, tm_min, and tm_sec.
+	 */
+	spin_lock_irq(&rtc_lock);
+	alm_tm->tm_sec = CMOS_READ(RTC_SECONDS_ALARM);
+	alm_tm->tm_min = CMOS_READ(RTC_MINUTES_ALARM);
+	alm_tm->tm_hour = CMOS_READ(RTC_HOURS_ALARM);
+	ctrl = CMOS_READ(RTC_CONTROL);
+	spin_unlock_irq(&rtc_lock);
+
+	if (!(ctrl & RTC_DM_BINARY) || RTC_ALWAYS_BCD) {
+		alm_tm->tm_sec = bcd2bin(alm_tm->tm_sec);
+		alm_tm->tm_min = bcd2bin(alm_tm->tm_min);
+		alm_tm->tm_hour = bcd2bin(alm_tm->tm_hour);
+	}
+}
+
+#ifdef RTC_IRQ
+/*
+ * Used to disable/enable interrupts for any one of UIE, AIE, PIE.
+ * Rumour has it that if you frob the interrupt enable/disable
+ * bits in RTC_CONTROL, you should read RTC_INTR_FLAGS, to
+ * ensure you actually start getting interrupts. Probably for
+ * compatibility with older/broken chipset RTC implementations.
+ * We also clear out any old irq data after an ioctl() that
+ * meddles with the interrupt enable/disable bits.
+ */
+
+static void mask_rtc_irq_bit_locked(unsigned char bit)
+{
+	unsigned char val;
+
+	if (hpet_mask_rtc_irq_bit(bit))
+		return;
+	val = CMOS_READ(RTC_CONTROL);
+	val &=  ~bit;
+	CMOS_WRITE(val, RTC_CONTROL);
+	CMOS_READ(RTC_INTR_FLAGS);
+
+	rtc_irq_data = 0;
+}
+
+static void set_rtc_irq_bit_locked(unsigned char bit)
+{
+	unsigned char val;
+
+	if (hpet_set_rtc_irq_bit(bit))
+		return;
+	val = CMOS_READ(RTC_CONTROL);
+	val |= bit;
+	CMOS_WRITE(val, RTC_CONTROL);
+	CMOS_READ(RTC_INTR_FLAGS);
+
+	rtc_irq_data = 0;
+}
+#endif
+
+MODULE_AUTHOR("Paul Gortmaker");
+MODULE_LICENSE("GPL");
+MODULE_ALIAS_MISCDEV(RTC_MINOR);