o Set clock to RTC at bootup.

o Add a /dev/rtc interface to set/read the clock.

2 files changed, 472 insertions, 2 deletions

diff --git a/arch/mips64/sgi-ip27/ip27-rtc.c b/arch/mips64/sgi-ip27/ip27-rtc.c
new file mode 100644
index 000000000..bf85c06f2
--- /dev/null
+++ b/arch/mips64/sgi-ip27/ip27-rtc.c
@@ -0,0 +1,332 @@
+/*
+ *	Driver for the SGS-Thomson M48T35 Timekeeper RAM chip
+ *
+ *	Real Time Clock interface for Linux	
+ *
+ *	TODO: Implement periodic interrupts.
+ *
+ *	Copyright (C) 2000 Silicon Graphics, Inc.
+ *	Written by Ulf Carlsson (ulfc@engr.sgi.com)
+ *
+ *	Based on code written by 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/rtc
+ *	pseudo-file for status information.
+ *
+ *	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.
+ *
+ */
+
+#define RTC_VERSION		"1.09b"
+
+#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/rtc.h>
+#include <linux/init.h>
+#include <linux/poll.h>
+#include <linux/proc_fs.h>
+
+#include <asm/m48t35.h>
+#include <asm/ioc3.h>
+#include <asm/io.h>
+#include <asm/uaccess.h>
+#include <asm/system.h>
+#include <asm/sn/klconfig.h>
+#include <asm/sn/sn0/ip27.h>
+#include <asm/sn/sn0/hub.h>
+
+static int rtc_ioctl(struct inode *inode, struct file *file,
+		     unsigned int cmd, unsigned long arg);
+
+static int rtc_read_proc(char *page, char **start, off_t off,
+                         int count, int *eof, void *data);
+
+static void get_rtc_time(struct rtc_time *rtc_tm);
+
+/*
+ *	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	*/
+
+static unsigned char rtc_status = 0;	/* bitmapped status byte.	*/
+static unsigned long rtc_freq = 0;	/* Current periodic IRQ rate	*/
+static struct m48t35_rtc *rtc;
+
+/*
+ *	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 = 1970;	/* year corresponding to 0x00	*/
+
+static const unsigned char days_in_mo[] = 
+{0, 31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31};
+
+static int rtc_ioctl(struct inode *inode, struct file *file, unsigned int cmd,
+		     unsigned long arg)
+{
+
+	struct rtc_time wtime; 
+
+	switch (cmd) {
+	case RTC_RD_TIME:	/* Read the time/date from 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 int yrs;
+		unsigned long flags;
+			
+		if (!capable(CAP_SYS_TIME))
+			return -EACCES;
+
+		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)
+			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 -= epoch) > 255)    /* They are unsigned */
+			return -EINVAL;
+
+		save_flags(flags);
+		cli();
+		if (yrs > 169) {
+			restore_flags(flags);
+			return -EINVAL;
+		}
+		if (yrs >= 100)
+			yrs -= 100;
+
+		BIN_TO_BCD(sec);
+		BIN_TO_BCD(min);
+		BIN_TO_BCD(hrs);
+		BIN_TO_BCD(day);
+		BIN_TO_BCD(mon);
+		BIN_TO_BCD(yrs);
+
+		rtc->control &= ~M48T35_RTC_SET;
+		rtc->year = yrs;
+		rtc->month = mon;
+		rtc->date = day;
+		rtc->hour = hrs;
+		rtc->min = min;
+		rtc->sec = sec;
+		rtc->control &= ~M48T35_RTC_SET;
+
+		restore_flags(flags);
+		return 0;
+	}
+	default:
+		return -EINVAL;
+	}
+	return copy_to_user((void *)arg, &wtime, sizeof wtime) ? -EFAULT : 0;
+}
+
+/*
+ *	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)
+{
+	if(rtc_status & RTC_IS_OPEN)
+		return -EBUSY;
+
+	MOD_INC_USE_COUNT;
+
+	rtc_status |= RTC_IS_OPEN;
+	return 0;
+}
+
+static int rtc_release(struct inode *inode, struct file *file)
+{
+	/*
+	 * Turn off all interrupts once the device is no longer
+	 * in use, and clear the data.
+	 */
+
+	MOD_DEC_USE_COUNT;
+
+	rtc_status &= ~RTC_IS_OPEN;
+	return 0;
+}
+
+/*
+ *	The various file operations we support.
+ */
+
+static struct file_operations rtc_fops = {
+	NULL,		/* No llseek (yet) */
+	NULL,		/* No read (yet) */
+	NULL,		/* No write */
+	NULL,		/* No readdir */
+	NULL,		/* No poll (yet) */
+	rtc_ioctl,
+	NULL,		/* No mmap */
+	rtc_open,
+	NULL,		/* flush */
+	rtc_release
+};
+
+static struct miscdevice rtc_dev=
+{
+	RTC_MINOR,
+	"rtc",
+	&rtc_fops
+};
+
+static int __init rtc_init(void)
+{
+	unsigned long flags;
+	nasid_t nid;
+
+	nid = get_nasid();
+	rtc = (struct m48t35_rtc *)
+	    KL_CONFIG_CH_CONS_INFO(nid)->memory_base + IOC3_BYTEBUS_DEV0;
+
+	printk(KERN_INFO "Real Time Clock Driver v%s\n", RTC_VERSION);
+	misc_register(&rtc_dev);
+	create_proc_read_entry ("rtc", 0, NULL, rtc_read_proc, NULL);
+
+	save_flags(flags);
+	cli();
+	restore_flags(flags);
+	rtc_freq = 1024;
+	return 0;
+}
+
+static void __exit rtc_exit (void)
+{
+	/* interrupts and timer disabled at this point by rtc_release */
+
+	remove_proc_entry ("rtc", NULL);
+	misc_deregister(&rtc_dev);
+}
+
+module_init(rtc_init);
+module_exit(rtc_exit);
+EXPORT_NO_SYMBOLS;
+
+/*
+ *	Info exported via "/proc/rtc".
+ */
+
+static int rtc_get_status(char *buf)
+{
+	char *p;
+	struct rtc_time tm;
+
+	/*
+	 * Just emulate the standard /proc/rtc
+	 */
+
+	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"
+	 	     "rtc_epoch\t: %04lu\n"
+		     "24hr\t\t: yes\n",
+		     tm.tm_hour, tm.tm_min, tm.tm_sec,
+		     tm.tm_year + 1900, tm.tm_mon + 1, tm.tm_mday, epoch);
+
+	return  p - buf;
+}
+
+static int rtc_read_proc(char *page, char **start, off_t off,
+                                 int count, int *eof, void *data)
+{
+        int len = rtc_get_status(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 void get_rtc_time(struct rtc_time *rtc_tm)
+{
+
+	unsigned long flags;
+
+	/*
+	 * Do we need to wait for the last update to finish?
+	 */
+
+	/*
+	 * Only the values that we read from the RTC are set. We leave
+	 * tm_wday, tm_yday and tm_isdst untouched. Even though the
+	 * RTC has RTC_DAY_OF_WEEK, we ignore it, as it is only updated
+	 * by the RTC when initially set to a non-zero value.
+	 */
+	save_flags(flags);
+	cli();
+        rtc->control |= M48T35_RTC_READ;
+	rtc_tm->tm_sec = rtc->sec;
+	rtc_tm->tm_min = rtc->min;
+	rtc_tm->tm_hour = rtc->hour;
+	rtc_tm->tm_mday = rtc->date;
+	rtc_tm->tm_mon = rtc->month;
+	rtc_tm->tm_year = rtc->year;
+	rtc->control &= ~M48T35_RTC_READ;
+	restore_flags(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 += (epoch - 1900)) <= 69)
+		rtc_tm->tm_year += 100;
+
+	rtc_tm->tm_mon--;
+}
diff --git a/arch/mips64/sgi-ip27/ip27-timer.c b/arch/mips64/sgi-ip27/ip27-timer.c
index 9950eb72d..c75fa725f 100644
--- a/arch/mips64/sgi-ip27/ip27-timer.c
+++ b/arch/mips64/sgi-ip27/ip27-timer.c
@@ -1,4 +1,4 @@
-/* $Id$
+/* $Id: ip27-timer.c,v 1.2 2000/01/27 01:05:24 ralf Exp $
  *
  * Copytight (C) 1999 Ralf Baechle (ralf@gnu.org)
  * Copytight (C) 1999 Silicon Graphics, Inc.
@@ -14,6 +14,8 @@
 
 #include <asm/pgtable.h>
 #include <asm/sgialib.h>
+#include <asm/ioc3.h>
+#include <asm/m48t35.h>
 #include <asm/sn/klconfig.h>
 #include <asm/sn/arch.h>
 #include <asm/sn/addrs.h>
@@ -32,10 +34,59 @@
 #define CYCLES_PER_SEC		(NSEC_PER_SEC/NSEC_PER_CYCLE)
 #define CYCLES_PER_JIFFY	(CYCLES_PER_SEC/HZ)
 
-static unsigned long ct_cur;    /* What counter should be at next timer irq */
+static unsigned long ct_cur;		/* What counter should be at next timer irq */
+static long last_rtc_update = 0;	/* Last time the rtc clock got updated */
 
 extern rwlock_t xtime_lock;
 
+
+static int set_rtc_mmss(unsigned long nowtime)
+{               
+        int retval = 0;
+        int real_seconds, real_minutes, cmos_minutes;
+        unsigned char save_control, save_freq_select;
+	struct m48t35_rtc *rtc;
+	nasid_t nid;
+
+	nid = get_nasid();
+	rtc = (struct m48t35_rtc *)
+	    KL_CONFIG_CH_CONS_INFO(nid)->memory_base + IOC3_BYTEBUS_DEV0;
+                
+	rtc->control |= M48T35_RTC_READ;
+	cmos_minutes = rtc->min;
+	BCD_TO_BIN(cmos_minutes);
+	rtc->control &= ~M48T35_RTC_READ;
+         
+        /*      
+         * Since we're only adjusting minutes and seconds,
+         * don't interfere with hour overflow. This avoids
+         * messing with unknown time zones but requires your
+         * RTC not to be off by more than 15 minutes
+         */     
+        real_seconds = nowtime % 60;
+        real_minutes = nowtime / 60;
+        if (((abs(real_minutes - cmos_minutes) + 15)/30) & 1)
+                real_minutes += 30;             /* correct for half hour time zone */           
+        real_minutes %= 60;
+                
+        if (abs(real_minutes - cmos_minutes) < 30) {
+		BIN_TO_BCD(real_seconds);
+		BIN_TO_BCD(real_minutes);
+		rtc->control |= M48T35_RTC_SET;
+                rtc->sec = real_seconds;
+                rtc->min = real_minutes;
+		rtc->control &= ~M48T35_RTC_SET;
+        } else {
+                printk(KERN_WARNING
+                       "set_rtc_mmss: can't update from %d to %d\n",
+                       cmos_minutes, real_minutes);
+                retval = -1;
+        }
+
+                
+        return retval;
+}
+
 void rt_timer_interrupt(struct pt_regs *regs)
 {
 	int irq = 7;				/* XXX Assign number */
@@ -52,6 +103,27 @@ again:
 
 	kstat.irqs[0][irq]++;
 	do_timer(regs);
+	
+        /*
+         * If we have an externally synchronized Linux clock, then update
+         * RTC clock accordingly every ~11 minutes. Set_rtc_mmss() has to be
+         * called as close as possible to when a second starts.
+         */
+
+        if ((time_status & STA_UNSYNC) == 0 &&
+            xtime.tv_sec > last_rtc_update + 660) {
+		if (xtime.tv_usec >= 1000000 - ((unsigned) tick) / 2) {
+			if (set_rtc_mmss(xtime.tv_sec + 1) == 0)
+				last_rtc_update = xtime.tv_sec;
+			else    
+				last_rtc_update = xtime.tv_sec - 600;
+		} else if (xtime.tv_usec <= ((unsigned) tick) / 2) {
+			if (set_rtc_mmss(xtime.tv_sec) == 0)
+				last_rtc_update = xtime.tv_sec;
+			else    
+				last_rtc_update = xtime.tv_sec - 600;
+		}
+        }
 
 	write_unlock(&xtime_lock);
 }
@@ -85,6 +157,69 @@ void do_settimeofday(struct timeval *tv)
 #include <asm/ioc3.h>
 #include <asm/pci/bridge.h>
 
+/* Converts Gregorian date to seconds since 1970-01-01 00:00:00.
+ * Assumes input in normal date format, i.e. 1980-12-31 23:59:59
+ * => year=1980, mon=12, day=31, hour=23, min=59, sec=59.
+ *
+ * [For the Julian calendar (which was used in Russia before 1917,
+ * Britain & colonies before 1752, anywhere else before 1582,
+ * and is still in use by some communities) leave out the
+ * -year/100+year/400 terms, and add 10.]
+ *
+ * This algorithm was first published by Gauss (I think).
+ *
+ * WARNING: this function will overflow on 2106-02-07 06:28:16 on
+ * machines were long is 32-bit! (However, as time_t is signed, we
+ * will already get problems at other places on 2038-01-19 03:14:08)
+ */
+static inline unsigned long mktime(unsigned int year, unsigned int mon,
+        unsigned int day, unsigned int hour,
+        unsigned int min, unsigned int sec)
+{       
+        if (0 >= (int) (mon -= 2)) {    /* 1..12 -> 11,12,1..10 */
+                mon += 12;      /* Puts Feb last since it has leap day */
+                year -= 1;
+        }
+        return (((
+            (unsigned long)(year/4 - year/100 + year/400 + 367*mon/12 + day) +
+              year*365 - 719499
+            )*24 + hour /* now have hours */
+           )*60 + min /* now have minutes */
+          )*60 + sec; /* finally seconds */
+}
+
+#define DEBUG_RTC
+
+static unsigned long __init get_m48t35_time(void)
+{       
+        unsigned int year, month, date, hour, min, sec;
+	struct m48t35_rtc *rtc;
+	nasid_t nid;
+
+	nid = get_nasid();
+	rtc = KL_CONFIG_CH_CONS_INFO(nid)->memory_base + IOC3_BYTEBUS_DEV0;
+
+        rtc->control |= M48T35_RTC_READ;
+	sec = rtc->sec;
+	min = rtc->min;
+	hour = rtc->hour;
+	date = rtc->date;
+	month = rtc->month;
+	year = rtc->year;
+	rtc->control &= ~M48T35_RTC_READ;
+
+        BCD_TO_BIN(sec);
+        BCD_TO_BIN(min);
+        BCD_TO_BIN(hour);
+        BCD_TO_BIN(date);
+        BCD_TO_BIN(month);
+        BCD_TO_BIN(year);
+
+        year += 1970;
+
+        return mktime(year, month, date, hour, min, sec);
+}
+
 extern void ioc3_eth_init(void);
 
 void __init time_init(void)
@@ -92,6 +227,9 @@ void __init time_init(void)
 	lboard_t *board;
 	klcpu_t *cpu;
 	int cpuid;
+	
+	xtime.tv_sec = get_m48t35_time();
+	xtime.tv_usec = 0;
 
 	/* Don't use ARCS.  ARCS is fragile.  Klconfig is simple and sane.  */
 	board = find_lboard(KLTYPE_IP27);