1 files changed, 138 insertions, 0 deletions
diff --git a/roms/ipxe/src/arch/i386/interface/pcbios/rtc_time.c b/roms/ipxe/src/arch/i386/interface/pcbios/rtc_time.c
new file mode 100644
index 00000000..67041d4c
--- /dev/null
+++ b/roms/ipxe/src/arch/i386/interface/pcbios/rtc_time.c
@@ -0,0 +1,138 @@
+/*
+ * Copyright (C) 2012 Michael Brown <mbrown@fensystems.co.uk>.
+ *
+ * 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 any later version.
+ *
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
+ * 02110-1301, USA.
+ */
+
+FILE_LICENCE ( GPL2_OR_LATER );
+
+/** @file
+ *
+ * RTC-based time source
+ *
+ */
+
+#include <stdint.h>
+#include <time.h>
+#include <rtc.h>
+#include <ipxe/time.h>
+
+/**
+ * Read RTC register
+ *
+ * @v address		Register address
+ * @ret data		Data
+ */
+static unsigned int rtc_readb ( int address ) {
+	outb ( address, CMOS_ADDRESS );
+	return inb ( CMOS_DATA );
+}
+
+/**
+ * Check if RTC update is in progress
+ *
+ * @ret is_busy		RTC update is in progress
+ */
+static int rtc_is_busy ( void ) {
+	return ( rtc_readb ( RTC_STATUS_A ) & RTC_STATUS_A_UPDATE_IN_PROGRESS );
+}
+
+/**
+ * Read RTC BCD register
+ *
+ * @v address		Register address
+ * @ret value		Value
+ */
+static unsigned int rtc_readb_bcd ( int address ) {
+	unsigned int bcd;
+
+	bcd = rtc_readb ( address );
+	return ( bcd - ( 6 * ( bcd >> 4 ) ) );
+}
+
+/**
+ * Read RTC time
+ *
+ * @ret time		Time, in seconds
+ */
+static time_t rtc_read_time ( void ) {
+	unsigned int status_b;
+	int is_binary;
+	int is_24hour;
+	unsigned int ( * read_component ) ( int address );
+	struct tm tm;
+	int is_pm;
+	unsigned int hour;
+	time_t time;
+
+	/* Wait for any in-progress update to complete */
+	while ( rtc_is_busy() ) {}
+
+	/* Determine RTC mode */
+	status_b = rtc_readb ( RTC_STATUS_B );
+	is_binary = ( status_b & RTC_STATUS_B_BINARY );
+	is_24hour = ( status_b & RTC_STATUS_B_24_HOUR );
+	read_component = ( is_binary ? rtc_readb : rtc_readb_bcd );
+
+	/* Read time values */
+	tm.tm_sec = read_component ( RTC_SEC );
+	tm.tm_min = read_component ( RTC_MIN );
+	hour = read_component ( RTC_HOUR );
+	if ( ! is_24hour ) {
+		is_pm = ( hour >= 80 );
+		hour = ( ( ( ( hour & 0x7f ) % 80 ) % 12 ) +
+			 ( is_pm ? 12 : 0 ) );
+	}
+	tm.tm_hour = hour;
+	tm.tm_mday = read_component ( RTC_MDAY );
+	tm.tm_mon = ( read_component ( RTC_MON ) - 1 );
+	tm.tm_year = ( read_component ( RTC_YEAR ) +
+		       100 /* Assume we are in the 21st century, since
+			    * this code was written in 2012 */ );
+
+	DBGC ( RTC_STATUS_A, "RTCTIME is %04d-%02d-%02d %02d:%02d:%02d "
+	       "(%s,%d-hour)\n", ( tm.tm_year + 1900 ), ( tm.tm_mon + 1 ),
+	       tm.tm_mday, tm.tm_hour, tm.tm_min, tm.tm_sec,
+	       ( is_binary ? "binary" : "BCD" ), ( is_24hour ? 24 : 12 ) );
+
+	/* Convert to seconds since the Epoch */
+	time = mktime ( &tm );
+
+	return time;
+}
+
+/**
+ * Get current time in seconds
+ *
+ * @ret time		Time, in seconds
+ */
+static time_t rtc_now ( void ) {
+	time_t time = 0;
+	time_t last_time;
+
+	/* Read time until we get two matching values in a row, in
+	 * case we end up reading a corrupted value in the middle of
+	 * an update.
+	 */
+	do {
+		last_time = time;
+		time = rtc_read_time();
+	} while ( time != last_time );
+
+	return time;
+}
+
+PROVIDE_TIME ( rtc, time_now, rtc_now );