hw: Implement wall time using RTC offset at boot

Addresses issue #31.

platform/hw/Makefile

@@ -38,7 +38,7 @@ endif
 
 LDFLAGS_BAKE+=	-L$(abspath rump/lib)
 
-OBJS_BMK-y+=		intr.o clock.o kernel.o multiboot.o undefs.o
+OBJS_BMK-y+=		intr.o clock.o clock_subr.o kernel.o multiboot.o undefs.o
 
 OBJS_BMK+= ${OBJS_BMK-y}
 

platform/hw/arch/x86/clock.c

@@ -25,6 +25,7 @@
  */
 
 #include <bmk/kernel.h>
+#include <bmk/clock_subr.h>
 
 #define NSEC_PER_SEC	1000000000ULL
 /* Minimum delta to sleep using PIT. Programming seems to have an overhead of
@@ -51,6 +52,9 @@ static const uint32_t pit_mult = (1ULL << 63) / ((NSEC_PER_SEC << 31) / TIMER_HZ
 static bmk_time_t time_base;
 static uint64_t tsc_base;
 
+/* RTC wall time offset at monotonic time base. */
+static bmk_time_t rtc_epochoffset;
+
 /* Set to 1 when the i8254 interrupt is handled. */
 static volatile int ticktock = 0;
 
@@ -147,6 +151,38 @@ rdtsc(void)
 	return val;
 }
 
+/*
+ * Read a RTC register. Due to PC platform braindead-ness also disables NMI.
+ */
+static inline uint8_t rtc_read(uint8_t reg)
+{
+
+	outb(RTC_COMMAND, reg | RTC_NMI_DISABLE);
+	return inb(RTC_DATA);
+}
+
+/*
+ * Return current RTC time. Note that due to waiting for the update cycle to
+ * complete, this call may take some time.
+ */
+static bmk_time_t rtc_gettimeofday(void)
+{
+	struct bmk_clock_ymdhms dt;
+
+	/* If time update in progress then spin until complete. */
+	while(rtc_read(RTC_STATUS_A) & RTC_UIP)
+		continue;
+
+	dt.dt_sec = bcdtobin(rtc_read(RTC_SEC));
+	dt.dt_min = bcdtobin(rtc_read(RTC_MIN));
+	dt.dt_hour = bcdtobin(rtc_read(RTC_HOUR));
+	dt.dt_day = bcdtobin(rtc_read(RTC_DAY));
+	dt.dt_mon = bcdtobin(rtc_read(RTC_MONTH));
+	dt.dt_year = bcdtobin(rtc_read(RTC_YEAR)) + 2000;
+
+	return bmk_clock_ymdhms_to_secs(&dt) * NSEC_PER_SEC;
+}
+
 void
 bmk_x86_initclocks(void)
 {
@@ -157,6 +193,12 @@ bmk_x86_initclocks(void)
 	outb(TIMER_CNTR, (TIMER_HZ / HZ) & 0xff);
 	outb(TIMER_CNTR, (TIMER_HZ / HZ) >> 8);
 
+	/*
+	 * Read RTC time to use as epoch offset. This must be done just before
+	 * tsc_base is initialised in order to get a correct offset.
+	 */
+	rtc_epochoffset = rtc_gettimeofday();
+
 	/*
 	 * Calculate TSC frequency by calibrating against an 0.1s delay
 	 * using the i8254 timer.
@@ -176,6 +218,11 @@ bmk_x86_initclocks(void)
 	 * (0.32) tsc_mult = NSEC_PER_SEC (32.32) / tsc_freq (32.0)
 	 */
 	tsc_mult = (NSEC_PER_SEC << 32) / tsc_freq;
+
+	/*
+	 * Monotonic time begins at tsc_base (first read of TSC before
+	 * calibration).
+	 */
 	time_base = mul64_32(tsc_base, tsc_mult);
 
 	/*
@@ -216,6 +263,16 @@ bmk_cpu_clock_now(void)
 	return time_base;
 }
 
+/*
+ * Return epoch offset (wall time offset to monotonic clock start).
+ */
+bmk_time_t
+bmk_cpu_clock_epochoffset(void)
+{
+
+	return rtc_epochoffset;
+}
+
 /*
  * Block the CPU until monotonic time is *no later than* the specified time.
  * Returns early if any non-timer interrupts are serviced, or if the requested

platform/hw/clock.c

@@ -38,5 +38,5 @@ bmk_time_t
 bmk_platform_clock_epochoffset(void)
 {
 
-	return 0; /* needs more bits */
+	return bmk_cpu_clock_epochoffset();
 }

platform/hw/clock_subr.c

@@ -0,0 +1,120 @@
+/*	$NetBSD: clock_subr.c,v 1.26 2014/12/22 18:09:20 christos Exp $	*/
+
+/*
+ * Copyright (c) 1988 University of Utah.
+ * Copyright (c) 1982, 1990, 1993
+ *	The Regents of the University of California.  All rights reserved.
+ *
+ * This code is derived from software contributed to Berkeley by
+ * the Systems Programming Group of the University of Utah Computer
+ * Science Department.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in the
+ *    documentation and/or other materials provided with the distribution.
+ * 3. Neither the name of the University nor the names of its contributors
+ *    may be used to endorse or promote products derived from this software
+ *    without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
+ * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+ * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
+ * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
+ * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
+ * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
+ * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
+ * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
+ * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
+ * SUCH DAMAGE.
+ *
+ * from: Utah $Hdr: clock.c 1.18 91/01/21$
+ *
+ *	@(#)clock.c	8.2 (Berkeley) 1/12/94
+ */
+
+/*
+ * Generic routines to convert between a POSIX date
+ * (seconds since 1/1/1970) and yr/mo/day/hr/min/sec
+ * Derived from arch/hp300/hp300/clock.c
+ */
+
+#include <bmk/kernel.h>
+#include <bmk/clock_subr.h>
+
+#define FEBRUARY	2
+
+/* for easier alignment:
+ * time from the epoch to 2000 (there were 7 leap years): */
+#define	DAYSTO2000	(365*30+7)
+
+/* 4 year intervals include 1 leap year */
+#define	DAYS4YEARS	(365*4+1)
+
+/* 100 year intervals include 24 leap years */
+#define	DAYS100YEARS	(365*100+24)
+
+/* 400 year intervals include 97 leap years */
+#define	DAYS400YEARS	(365*400+97)
+
+bmk_time_t
+bmk_clock_ymdhms_to_secs(struct bmk_clock_ymdhms *dt)
+{
+	uint64_t secs, i, year, days;
+
+	year = dt->dt_year;
+
+	/*
+	 * Compute days since start of time
+	 * First from years, then from months.
+	 */
+	if (year < POSIX_BASE_YEAR)
+		return 0;
+	days = 0;
+	if (is_leap_year(year) && dt->dt_mon > FEBRUARY)
+		days++;
+
+	if (year < 2000) {
+		/* simple way for early years */
+		for (i = POSIX_BASE_YEAR; i < year; i++)
+			days += days_per_year(i);
+	} else {
+		/* years are properly aligned */
+		days += DAYSTO2000;
+		year -= 2000;
+
+		i = year / 400;
+		days += i * DAYS400YEARS;
+		year -= i * 400;
+
+		i = year / 100;
+		days += i * DAYS100YEARS;
+		year -= i * 100;
+
+		i = year / 4;
+		days += i * DAYS4YEARS;
+		year -= i * 4;
+
+		for (i = dt->dt_year-year; i < dt->dt_year; i++)
+			days += days_per_year(i);
+	}
+
+
+	/* Months */
+	for (i = 1; i < dt->dt_mon; i++)
+	  	days += days_in_month(i);
+	days += (dt->dt_day - 1);
+
+	/* Add hours, minutes, seconds. */
+	secs = (((uint64_t)days
+	    * 24 + dt->dt_hour)
+	    * 60 + dt->dt_min)
+	    * 60 + dt->dt_sec;
+
+	return secs;
+}

platform/hw/include/arch/x86/reg.h

@@ -14,3 +14,16 @@
 #define TIMER_ONESHOT	0x08
 #define TIMER_16BIT	0x30
 #define TIMER_HZ	1193182
+
+#define	RTC_COMMAND	0x70
+#define	RTC_DATA	0x71
+#define RTC_NMI_DISABLE	(1<<8)
+#define RTC_NMI_ENABLE	0
+#define	RTC_SEC		0x00
+#define	RTC_MIN		0x02
+#define	RTC_HOUR	0x04
+#define	RTC_DAY		0x07
+#define	RTC_MONTH	0x08
+#define	RTC_YEAR	0x09
+#define	RTC_STATUS_A	0x0a
+#define	RTC_UIP		(1<<7)

platform/hw/include/bmk/clock_subr.h

@@ -0,0 +1,112 @@
+/*-
+ * Copyright (c) 1996 The NetBSD Foundation, Inc.
+ * All rights reserved.
+ *
+ * This code is derived from software contributed to The NetBSD Foundation
+ * by Gordon W. Ross
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in the
+ *    documentation and/or other materials provided with the distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS
+ * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
+ * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
+ * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS
+ * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
+ * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
+ * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
+ * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
+ * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
+ * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
+ * POSSIBILITY OF SUCH DAMAGE.
+ */
+
+#ifndef _BMK_CLOCK_SUBR_H_
+#define _BMK_CLOCK_SUBR_H_
+
+#include <bmk/kernel.h>
+
+/* Some handy constants. */
+#define SECS_PER_MINUTE		60
+#define SECS_PER_HOUR		3600
+#define SECS_PER_DAY		86400
+#define DAYS_PER_COMMON_YEAR    365
+#define DAYS_PER_LEAP_YEAR      366
+#define SECS_PER_COMMON_YEAR	(SECS_PER_DAY * DAYS_PER_COMMON_YEAR)
+#define SECS_PER_LEAP_YEAR	(SECS_PER_DAY * DAYS_PER_LEAP_YEAR)
+
+/* Traditional POSIX base year */
+#define	POSIX_BASE_YEAR	1970
+
+/* Some handy functions */
+static inline int
+days_in_month(int m)
+{
+	switch (m) {
+	case 2:
+		return 28;
+	case 4: case 6: case 9: case 11:
+		return 30;
+	case 1: case 3: case 5: case 7: case 8: case 10: case 12:
+		return 31;
+	default:
+		return -1;
+	}
+}
+
+/*
+ * This inline avoids some unnecessary modulo operations
+ * as compared with the usual macro:
+ *   ( ((year % 4) == 0 &&
+ *      (year % 100) != 0) ||
+ *     ((year % 400) == 0) )
+ * It is otherwise equivalent.
+ */
+static inline int
+is_leap_year(uint64_t year)
+{
+	if ((year & 3) != 0)
+		return 0;
+
+	if ((year % 100) != 0)
+		return 1;
+
+	return (year % 400) == 0;
+}
+
+static inline int
+days_per_year(uint64_t year)
+{
+	return is_leap_year(year) ? DAYS_PER_LEAP_YEAR : DAYS_PER_COMMON_YEAR;
+}
+
+/*
+ * "POSIX time" to/from "YY/MM/DD/hh/mm/ss"
+ */
+struct bmk_clock_ymdhms {
+	uint64_t dt_year;
+	uint8_t dt_mon;
+	uint8_t dt_day;
+	uint8_t dt_hour;
+	uint8_t dt_min;
+	uint8_t dt_sec;
+};
+
+bmk_time_t bmk_clock_ymdhms_to_secs(struct bmk_clock_ymdhms *);
+
+/*
+ * BCD to binary.
+ */
+static inline unsigned int
+bcdtobin(unsigned int bcd)
+{
+        return ((bcd >> 4) & 0x0f) * 10 + (bcd & 0x0f);
+}
+
+#endif /* _BMK_CLOCK_SUBR_H_ */

platform/hw/include/bmk/kernel.h

@@ -22,6 +22,7 @@ int bmk_cpu_intr_init(int);
 void bmk_cpu_intr_ack(void);
 
 bmk_time_t bmk_cpu_clock_now(void);
+bmk_time_t bmk_cpu_clock_epochoffset(void);
 
 void bmk_isr_clock(void);
 void bmk_isr(int);