rtc: Add an RTC API, and implement it for x86.

This CL adds an API for RTC drivers, and implements its two functions,
rtc_get and rtc_set, for x86's RTC. The function which resets the clock when the
CMOS as lost state now uses the RTC driver instead of accessing the those
registers directly.

BUG=None
TEST=Built and booted on Link with the event log code modified to use
the RTC interface. Verified that the event times were accurate.
BRANCH=nyan

Original-Change-Id: Ifa807898e583254e57167fd44932ea86627a02ee
Original-Signed-off-by: Gabe Black <gabeblack@google.com>
Original-Reviewed-on: https://chromium-review.googlesource.com/197795
Original-Reviewed-by: David Hendricks <dhendrix@chromium.org>
Original-Tested-by: Gabe Black <gabeblack@chromium.org>
Original-Commit-Queue: Gabe Black <gabeblack@chromium.org>

This is the first half of the patch.
(cherry picked from commit 9e0fd75142d29afe34f6c6b9ce0099f478ca5a93)
Signed-off-by: Marc Jones <marc.jones@se-eng.com>

Change-Id: I159f9b4872a0bb932961b4168b180c087dfb1883
Reviewed-on: http://review.coreboot.org/7889
Tested-by: build bot (Jenkins)
Reviewed-by: Edward O'Callaghan <eocallaghan@alterapraxis.com>
Reviewed-by: Kyösti Mälkki <kyosti.malkki@gmail.com>

src/drivers/pc80/Kconfig

@@ -22,3 +22,7 @@ config LPC_TPM
 	  Enable this option to enable TPM support in coreboot.
 
 	  If unsure, say N.
+
+config DRIVERS_MC146818
+	bool
+	default y if ARCH_X86

src/drivers/pc80/Makefile.inc

@@ -1,5 +1,5 @@
-romstage-y += mc146818rtc.c
+romstage-$(CONFIG_DRIVERS_MC146818) += mc146818rtc.c
-ramstage-y += mc146818rtc.c
+ramstage-$(CONFIG_DRIVERS_MC146818) += mc146818rtc.c
 ramstage-y += isa-dma.c
 ramstage-y += i8254.c
 ramstage-y += i8259.c
@@ -7,7 +7,10 @@ ramstage-$(CONFIG_UDELAY_IO) += udelay_io.c
 ramstage-y += keyboard.c
 ramstage-$(CONFIG_SPKMODEM) += spkmodem.c
 
+ifeq ($(CONFIG_DRIVERS_MC146818),y)
 romstage-$(CONFIG_USE_OPTION_TABLE) += mc146818rtc_early.c
+endif
+
 romstage-$(CONFIG_LPC_TPM) += tpm.c
 romstage-$(CONFIG_SPKMODEM) += spkmodem.c
 
@@ -17,4 +20,4 @@ cbfs-files-$(CONFIG_HAVE_CMOS_DEFAULT) += cmos.default
 cmos.default-file = $(CONFIG_CMOS_DEFAULT_FILE):nvramtool
 cmos.default-type = 0xaa
 
-smm-y += mc146818rtc.c
+smm-$(CONFIG_DRIVERS_MC146818) += mc146818rtc.c

src/drivers/pc80/mc146818rtc.c

@@ -1,28 +1,51 @@
+/*
+ * This file is part of the coreboot project.
+ *
+ * Copyright 2014 The Chromium OS Authors. All rights reserved.
+ *
+ * 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; version 2 of the License.
+ *
+ * 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 St, Fifth Floor, Boston, MA 02110-1301 USA
+ */
+
+#include <arch/acpi.h>
+#include <bcd.h>
 #include <stdint.h>
 #include <version.h>
 #include <console/console.h>
 #include <pc80/mc146818rtc.h>
 #include <boot/coreboot_tables.h>
+#include <rtc.h>
 #include <string.h>
 #if CONFIG_USE_OPTION_TABLE
 #include "option_table.h"
 #include <cbfs.h>
 #endif
-#include <arch/acpi.h>
 
 
-static void cmos_update_date(u8 has_century)
+static void cmos_reset_date(u8 has_century)
 {
 	/* Now setup a default date equals to the build date */
-	cmos_write(0, RTC_CLK_SECOND);
+	struct rtc_time time = {
-	cmos_write(0, RTC_CLK_MINUTE);
+		.sec = 0,
-	cmos_write(1, RTC_CLK_HOUR);
+		.min = 0,
-	cmos_write(coreboot_build_date.weekday + 1, RTC_CLK_DAYOFWEEK);
+		.hour = 1,
-	cmos_write(coreboot_build_date.day, RTC_CLK_DAYOFMONTH);
+		.mday = bcd2bin(coreboot_build_date.day),
-	cmos_write(coreboot_build_date.month, RTC_CLK_MONTH);
+		.mon = bcd2bin(coreboot_build_date.month),
-	cmos_write(coreboot_build_date.year, RTC_CLK_YEAR);
+		.year = (bcd2bin(coreboot_build_date.century) * 100) +
-	if (has_century)
+			bcd2bin(coreboot_build_date.year),
-		cmos_write(coreboot_build_date.century, RTC_CLK_ALTCENTURY);
+		.wday = bcd2bin(coreboot_build_date.weekday)
+	};
+	rtc_set(&time, has_century);
 }
 
 #if CONFIG_USE_OPTION_TABLE
@@ -50,15 +73,8 @@ static void cmos_set_checksum(int range_start, int range_end, int cks_loc)
 }
 #endif
 
-#if CONFIG_ARCH_X86
 #define RTC_CONTROL_DEFAULT (RTC_24H)
 #define RTC_FREQ_SELECT_DEFAULT (RTC_REF_CLCK_32KHZ | RTC_RATE_1024HZ)
-#else
-#if CONFIG_ARCH_ALPHA
-#define RTC_CONTROL_DEFAULT (RTC_SQWE | RTC_24H)
-#define RTC_FREQ_SELECT_DEFAULT (RTC_REF_CLCK_32KHZ | RTC_RATE_1024HZ)
-#endif
-#endif
 
 #ifndef __SMM__
 void cmos_init(int invalid)
@@ -107,7 +123,7 @@ void cmos_init(int invalid)
 			cmos_write(0, i);
 #endif
 		if (cmos_invalid)
-			cmos_update_date(RTC_HAS_NO_ALTCENTURY);
+			cmos_reset_date(RTC_HAS_NO_ALTCENTURY);
 
 		printk(BIOS_WARNING, "RTC:%s%s%s%s\n",
 			invalid?" Clear requested":"",
@@ -323,5 +339,36 @@ void cmos_check_update_date(u8 has_century)
 	 * if the date is valid.
 	 */
 	if (century > 0x99 || year > 0x99) /* Invalid date */
-		cmos_update_date(has_century);
+		cmos_reset_date(has_century);
+}
+
+int rtc_set(const struct rtc_time *time, u8 has_century)
+{
+	cmos_write(bin2bcd(time->sec), RTC_CLK_SECOND);
+	cmos_write(bin2bcd(time->min), RTC_CLK_MINUTE);
+	cmos_write(bin2bcd(time->hour), RTC_CLK_HOUR);
+	cmos_write(bin2bcd(time->mday), RTC_CLK_DAYOFMONTH);
+	cmos_write(bin2bcd(time->mon), RTC_CLK_MONTH);
+	cmos_write(bin2bcd(time->year % 100), RTC_CLK_YEAR);
+	if (has_century)
+		cmos_write(bin2bcd(time->year / 100),
+			   RTC_CLK_ALTCENTURY);
+	cmos_write(bin2bcd(time->wday + 1), RTC_CLK_DAYOFWEEK);
+	return 0;
+}
+
+int rtc_get(struct rtc_time *time, u8 has_century)
+{
+	time->sec = bcd2bin(cmos_read(RTC_CLK_SECOND));
+	time->min = bcd2bin(cmos_read(RTC_CLK_MINUTE));
+	time->hour = bcd2bin(cmos_read(RTC_CLK_HOUR));
+	time->mday = bcd2bin(cmos_read(RTC_CLK_DAYOFMONTH));
+	time->mon = bcd2bin(cmos_read(RTC_CLK_MONTH));
+	time->year = bcd2bin(cmos_read(RTC_CLK_YEAR));
+	if (has_century)
+		time->year += bcd2bin(cmos_read(RTC_CLK_ALTCENTURY)) * 100;
+	else
+		time->year += 2000;
+	time->wday = bcd2bin(cmos_read(RTC_CLK_DAYOFWEEK)) - 1;
+	return 0;
 }

src/include/bcd.h

@@ -0,0 +1,35 @@
+/*
+ * This file is part of the coreboot project.
+ *
+ * Copyright 2014 Google, Inc.
+ *
+ * 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; version 2 of the License.
+ *
+ * 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 St, Fifth Floor, Boston, MA, 02110-1301 USA
+ */
+
+#ifndef _BCD_H_
+#define _BCD_H_
+
+#include <stdint.h>
+
+static inline uint8_t bcd2bin(uint8_t val)
+{
+	return ((val >> 4) & 0xf) * 10 + (val & 0xf);
+}
+
+static inline uint8_t bin2bcd(uint8_t val)
+{
+	return ((val / 10) << 4) | (val % 10);
+}
+
+#endif /* _BCD_H_ */

src/include/rtc.h

@@ -0,0 +1,37 @@
+/*
+ * This file is part of the coreboot project.
+ *
+ * Copyright 2014 Google, Inc.
+ *
+ * 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; version 2 of the License.
+ *
+ * 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 St, Fifth Floor, Boston, MA, 02110-1301 USA
+ */
+
+#ifndef _RTC_H_
+#define _RTC_H_
+
+struct rtc_time
+{
+	int sec;
+	int min;
+	int hour;
+	int mday;
+	int mon;
+	int year;
+	int wday;
+};
+
+int rtc_set(const struct rtc_time *time, u8 has_century);
+int rtc_get(struct rtc_time *time, u8 has_century);
+
+#endif /* _RTC_H_ */