rtc: Add an RTC driver for the TI TPS65913 PMIC.

The TPS65913 PMIC has an RTC built into it. This change adds
a driver for it which implements the new RTC API.

BUG=chrome-os-partner:33764
BRANCH=None
TEST=Compiles and boots to kernel prompt on ryu. Timestamps for event log
verified across multiple boots.

Change-Id: I49ec9b78afc53f1cbd4be09e448cdae6077fb710
Signed-off-by: Patrick Georgi <pgeorgi@chromium.org>
Original-Commit-Id: c16c11e620c830e7a73a2a24fe4823ccea0f3c39
Original-Change-Id: If1d549ea2361d0de6be75fd24b9e9810a6df7457
Original-Signed-off-by: Furquan Shaikh <furquan@google.com>
Original-Reviewed-on: https://chromium-review.googlesource.com/229414
Original-Reviewed-by: Aaron Durbin <adurbin@chromium.org>
Original-Tested-by: Furquan Shaikh <furquan@chromium.org>
Original-Commit-Queue: Furquan Shaikh <furquan@chromium.org>
Reviewed-on: http://review.coreboot.org/9425
Reviewed-by: Paul Menzel <paulepanter@users.sourceforge.net>
Tested-by: build bot (Jenkins)
Reviewed-by: Stefan Reinauer <stefan.reinauer@coreboot.org>

1 files changed, 155 insertions, 0 deletions

diff --git a/src/drivers/ti/tps65913/tps65913rtc.c b/src/drivers/ti/tps65913/tps65913rtc.c
new file mode 100644
index 0000000000..46dd4f9dd0
--- /dev/null
+++ b/src/drivers/ti/tps65913/tps65913rtc.c
@@ -0,0 +1,155 @@
+/*
+ * 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
+ */
+
+#include <bcd.h>
+#include <console/console.h>
+#include <device/i2c.h>
+#include <rtc.h>
+#include <stdint.h>
+
+enum TPS65913_RTC_REG {
+	TPS65913_SECONDS_REG		= 0x00,
+	TPS65913_MINUTES_REG		= 0x01,
+	TPS65913_HOURS_REG		= 0x02,
+	TPS65913_DAYS_REG		= 0x03,
+	TPS65913_MONTHS_REG		= 0x04,
+	TPS65913_YEARS_REG		= 0x05,
+	TPS65913_WEEKS_REG		= 0x06,
+	TPS65913_RTC_CTRL_REG		= 0x10,
+	TPS65913_RTC_STATUS_REG	= 0x11,
+	TPS65913_RTC_INTERRUPS_REG	= 0x12,
+};
+
+enum {
+	TPS65913_RTC_CTRL_STOP		= (1 << 0),
+	TPS65913_RTC_CTRL_GET_TIME	= (1 << 6),
+
+	TPS65913_RTC_STATUS_RUN	= (1 << 1),
+	TPS65913_RTC_RUNNING		= (1 << 1),
+	TPS65913_RTC_FROZEN		= (0 << 1),
+};
+
+static inline uint8_t tps65913_read(enum TPS65913_RTC_REG reg)
+{
+	uint8_t val;
+	i2c_readb(CONFIG_DRIVERS_TI_TPS65913_RTC_BUS,
+		  CONFIG_DRIVERS_TI_TPS65913_RTC_ADDR, reg, &val);
+	return val;
+}
+
+static inline void tps65913_write(enum TPS65913_RTC_REG reg, uint8_t val)
+{
+	i2c_writeb(CONFIG_DRIVERS_TI_TPS65913_RTC_BUS,
+		   CONFIG_DRIVERS_TI_TPS65913_RTC_ADDR, reg, val);
+}
+
+static void tps65913_rtc_ctrl_clear(uint8_t bit)
+{
+	uint8_t control = tps65913_read(TPS65913_RTC_CTRL_REG);
+
+	control &= ~bit;
+	tps65913_write(TPS65913_RTC_CTRL_REG, control);
+}
+
+static void tps65913_rtc_ctrl_set(uint8_t bit)
+{
+	uint8_t control = tps65913_read(TPS65913_RTC_CTRL_REG);
+
+	control |= TPS65913_RTC_CTRL_GET_TIME;
+	tps65913_write(TPS65913_RTC_CTRL_REG, control);
+}
+
+static int tps65913_is_rtc_running(void)
+{
+	uint8_t status = tps65913_read(TPS65913_RTC_STATUS_REG);
+	return ((status & TPS65913_RTC_STATUS_RUN) == TPS65913_RTC_RUNNING);
+}
+
+/*
+ * This function ensures that current time is copied to shadow registers. Then a
+ * normal read on TC registers reads from the shadow instead of current TC
+ * registers. This helps prevent the accidental change in counters while
+ * reading. In order to ensure that the current TC registers are copied into
+ * shadow registers, GET_TIME bit needs to be set to 0 and then to 1.
+ */
+static void tps65913_rtc_shadow(void)
+{
+	tps65913_rtc_ctrl_clear(TPS65913_RTC_CTRL_GET_TIME);
+	tps65913_rtc_ctrl_set(TPS65913_RTC_CTRL_GET_TIME);
+}
+
+static int tps65913_rtc_stop(void)
+{
+	/* Clearing stop bit freezes RTC */
+	tps65913_rtc_ctrl_clear(TPS65913_RTC_CTRL_STOP);
+
+	if (tps65913_is_rtc_running()) {
+		printk(BIOS_ERR, "Could not stop RTC\n");
+		return 1;
+	}
+
+	return 0;
+}
+
+static int tps65913_rtc_start(void)
+{
+	/* Setting stop bit starts RTC */
+	tps65913_rtc_ctrl_set(TPS65913_RTC_CTRL_STOP);
+
+	if (!tps65913_is_rtc_running()) {
+		printk(BIOS_ERR, "Could not start RTC\n");
+		return 1;
+	}
+
+	return 0;
+}
+
+int rtc_set(const struct rtc_time *time)
+{
+	/* Before setting the time, ensure that rtc is stopped */
+	if (tps65913_rtc_stop())
+		return 1;
+
+	tps65913_write(TPS65913_SECONDS_REG, bin2bcd(time->sec));
+	tps65913_write(TPS65913_MINUTES_REG, bin2bcd(time->min));
+	tps65913_write(TPS65913_HOURS_REG, bin2bcd(time->hour));
+	tps65913_write(TPS65913_DAYS_REG, bin2bcd(time->mday));
+	tps65913_write(TPS65913_MONTHS_REG, bin2bcd(time->mon));
+	tps65913_write(TPS65913_YEARS_REG, bin2bcd(time->year));
+
+	/* Re-start rtc */
+	if (tps65913_rtc_start())
+		return 1;
+
+	return 0;
+}
+
+int rtc_get(struct rtc_time *time)
+{
+	tps65913_rtc_shadow();
+
+	time->sec = bcd2bin(tps65913_read(TPS65913_SECONDS_REG) & 0x7f);
+	time->min = bcd2bin(tps65913_read(TPS65913_MINUTES_REG) & 0x7f);
+	time->hour = bcd2bin(tps65913_read(TPS65913_HOURS_REG) & 0x3f);
+	time->mday = bcd2bin(tps65913_read(TPS65913_DAYS_REG) & 0x3f);
+	time->mon = bcd2bin(tps65913_read(TPS65913_MONTHS_REG) & 0x1f);
+	time->year = bcd2bin(tps65913_read(TPS65913_YEARS_REG) & 0xff);
+
+	return 0;
+}