rtc: Add an RTC driver for the AS3722 PMIC.

The AS3722 PMIC, like many PMICs, has an RTC built into it. This change adds a
driver for it which implements the new RTC API.

BUG=None
TEST=Built and booted with the event log code modified to use this interface.
Verified that events had accurate timestamps.
BRANCH=nyan

Original-Change-Id: I400adccbf84221dcba8d520276bb91b389f72268
Original-Signed-off-by: Gabe Black <gabeblack@google.com>
Original-Reviewed-on: https://chromium-review.googlesource.com/197796
Original-Reviewed-by: Gabe Black <gabeblack@chromium.org>
Original-Tested-by: Gabe Black <gabeblack@chromium.org>
Original-Commit-Queue: Gabe Black <gabeblack@chromium.org>
(cherry picked from commit 011e49beba3a99abbd122866891e3c20bf1188d2)
Signed-off-by: Marc Jones <marc.jones@se-eng.com>

Change-Id: Ibc1d342062c7853a30d195496c077e37a02b35b0
Reviewed-on: http://review.coreboot.org/7890
Reviewed-by: David Hendricks <dhendrix@chromium.org>
Tested-by: build bot (Jenkins)
Reviewed-by: Kyösti Mälkki <kyosti.malkki@gmail.com>

src/drivers/Kconfig

@@ -17,6 +17,7 @@
 ## Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
 ##
 
+source src/drivers/ams/Kconfig
 source src/drivers/ati/Kconfig
 source src/drivers/dec/Kconfig
 source src/drivers/elog/Kconfig

src/drivers/Makefile.inc

@@ -17,6 +17,7 @@
 ## Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
 ##
 
+subdirs-y += ams
 subdirs-y += ati
 subdirs-y += dec
 subdirs-y += emulation

src/drivers/ams/Kconfig

@@ -0,0 +1,11 @@
+config DRIVERS_AS3722_RTC
+	bool "AS3722 RTC support"
+	default n
+
+config DRIVERS_AS3722_RTC_BUS
+	int "AS3722 RTC bus"
+	depends on DRIVERS_AS3722_RTC
+
+config DRIVERS_AS3722_RTC_ADDR
+	hex "AS3722 RTC chip address"
+	depends on DRIVERS_AS3722_RTC

src/drivers/ams/Makefile.inc

@@ -0,0 +1 @@
+ramstage-$(CONFIG_DRIVERS_AS3722_RTC) += as3722rtc.c

src/drivers/ams/as3722rtc.c

@@ -0,0 +1,91 @@
+/*
+ * 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 <bcd.h>
+#include <console/console.h>
+#include <device/i2c.h>
+#include <rtc.h>
+#include <stdint.h>
+
+enum AS3722_RTC_REG
+{
+	AS3722_RTC_CONTROL = 0x60,
+	AS3722_RTC_SECOND = 0x61,
+	AS3722_RTC_MINUTE = 0x62,
+	AS3722_RTC_HOUR = 0x63,
+	AS3722_RTC_DAY = 0x64,
+	AS3722_RTC_MONTH = 0x65,
+	AS3722_RTC_YEAR = 0x66
+};
+
+enum {
+	AS3722_RTC_CONTROL_ON = 0x1 << 2
+};
+
+static uint8_t as3722_read(enum AS3722_RTC_REG reg)
+{
+	uint8_t val;
+	i2c_readb(CONFIG_DRIVERS_AS3722_RTC_BUS,
+		  CONFIG_DRIVERS_AS3722_RTC_ADDR, reg, &val);
+	return val;
+}
+
+static void as3722_write(enum AS3722_RTC_REG reg, uint8_t val)
+{
+	i2c_writeb(CONFIG_DRIVERS_AS3722_RTC_BUS,
+		   CONFIG_DRIVERS_AS3722_RTC_ADDR, reg, val);
+}
+
+static void as3722rtc_init(void)
+{
+	static int initialized;
+	if (initialized)
+		return;
+
+	uint8_t control = as3722_read(AS3722_RTC_CONTROL);
+	as3722_write(AS3722_RTC_CONTROL, control | AS3722_RTC_CONTROL_ON);
+
+	initialized = 1;
+}
+
+int rtc_set(const struct rtc_time *time)
+{
+	as3722rtc_init();
+
+	as3722_write(AS3722_RTC_SECOND, bin2bcd(time->sec));
+	as3722_write(AS3722_RTC_MINUTE, bin2bcd(time->min));
+	as3722_write(AS3722_RTC_HOUR, bin2bcd(time->hour));
+	as3722_write(AS3722_RTC_DAY, bin2bcd(time->mday));
+	as3722_write(AS3722_RTC_MONTH, bin2bcd(time->mon + 1));
+	as3722_write(AS3722_RTC_YEAR, bin2bcd(time->year));
+	return 0;
+}
+
+int rtc_get(struct rtc_time *time)
+{
+	as3722rtc_init();
+
+	time->sec = bcd2bin(as3722_read(AS3722_RTC_SECOND) & 0x7f);
+	time->min = bcd2bin(as3722_read(AS3722_RTC_MINUTE) & 0x7f);
+	time->hour = bcd2bin(as3722_read(AS3722_RTC_HOUR) & 0x3f);
+	time->mday = bcd2bin(as3722_read(AS3722_RTC_DAY) & 0x3f);
+	time->mon = bcd2bin(as3722_read(AS3722_RTC_MONTH) & 0x1f) - 1;
+	time->year = bcd2bin(as3722_read(AS3722_RTC_YEAR) & 0x7f);
+	return 0;
+}