drivers/i2c: Add new driver for RTC type RX6110 SA

This driver enables the usage of the external RTC chip RX6110 SA
(http://www5.epsondevice.com/en/products/i2c/rx6110sab.html) which is
connected to the I2C bus. The I2C address of this device is fixed. One
can change parameters in the device tree so that the used setup can be
adapted to match the configuration of the device on the mainboard.

Change-Id: I1290a10c2d5ad76a317c99c8b92a013309a605d6
Signed-off-by: Mario Scheithauer <mario.scheithauer@siemens.com>
Reviewed-on: https://review.coreboot.org/19625
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Werner Zeh <werner.zeh@siemens.com>

1 files changed, 146 insertions, 0 deletions

diff --git a/src/drivers/i2c/rx6110sa/rx6110sa.c b/src/drivers/i2c/rx6110sa/rx6110sa.c
new file mode 100644
index 0000000000..743b708c19
--- /dev/null
+++ b/src/drivers/i2c/rx6110sa/rx6110sa.c
@@ -0,0 +1,146 @@
+/*
+ * This file is part of the coreboot project.
+ *
+ * Copyright 2017 Siemens AG.
+ *
+ * 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.
+ */
+
+#include <device/i2c.h>
+#include <device/device.h>
+#include <version.h>
+#include <console/console.h>
+#include <bcd.h>
+#include "chip.h"
+#include "rx6110sa.h"
+
+#define I2C_BUS_NUM	(dev->bus->secondary - 1)
+#define I2C_DEV_NUM	(dev->path.i2c.device)
+
+/* Set RTC date from coreboot build date. */
+static void rx6110sa_set_build_date(struct device *dev)
+{
+	i2c_writeb(I2C_BUS_NUM, I2C_DEV_NUM, YEAR_REG,
+			coreboot_build_date.year);
+	i2c_writeb(I2C_BUS_NUM, I2C_DEV_NUM, MONTH_REG,
+			coreboot_build_date.month);
+	i2c_writeb(I2C_BUS_NUM, I2C_DEV_NUM, DAY_REG,
+			coreboot_build_date.day);
+	i2c_writeb(I2C_BUS_NUM, I2C_DEV_NUM, WEEK_REG,
+			(1 << coreboot_build_date.weekday));
+}
+
+/* Set RTC date from user defined date (available in e.g. device tree). */
+static void rx6110sa_set_user_date(struct device *dev)
+{
+	struct drivers_i2c_rx6110sa_config *config = dev->chip_info;
+
+	i2c_writeb(I2C_BUS_NUM, I2C_DEV_NUM, YEAR_REG,
+			bin2bcd(config->user_year));
+	i2c_writeb(I2C_BUS_NUM, I2C_DEV_NUM, MONTH_REG,
+			bin2bcd(config->user_month));
+	i2c_writeb(I2C_BUS_NUM, I2C_DEV_NUM, DAY_REG,
+			bin2bcd(config->user_day));
+	i2c_writeb(I2C_BUS_NUM, I2C_DEV_NUM, WEEK_REG,
+			(1 << config->user_weekday));
+}
+
+static void rx6110sa_final(struct device *dev)
+{
+	uint8_t hour, minute, second, year, month, day;
+
+	/* Read back current RTC date and time and print it to the console. */
+	i2c_readb(I2C_BUS_NUM, I2C_DEV_NUM, HOUR_REG, &hour);
+	i2c_readb(I2C_BUS_NUM, I2C_DEV_NUM, MINUTE_REG, &minute);
+	i2c_readb(I2C_BUS_NUM, I2C_DEV_NUM, SECOND_REG, &second);
+	i2c_readb(I2C_BUS_NUM, I2C_DEV_NUM, YEAR_REG, &year);
+	i2c_readb(I2C_BUS_NUM, I2C_DEV_NUM, MONTH_REG, &month);
+	i2c_readb(I2C_BUS_NUM, I2C_DEV_NUM, DAY_REG, &day);
+
+	printk(BIOS_INFO, "%s: Current date %02d.%02d.%02d %02d:%02d:%02d\n",
+		dev->chip_ops->name, bcd2bin(month), bcd2bin(day),
+		bcd2bin(year), bcd2bin(hour), bcd2bin(minute), bcd2bin(second));
+}
+
+static void rx6110sa_init(struct device *dev)
+{
+	struct drivers_i2c_rx6110sa_config *config = dev->chip_info;
+	uint8_t reg;
+
+	/* Do a dummy read first. */
+	i2c_readb(I2C_BUS_NUM, I2C_DEV_NUM, SECOND_REG, &reg);
+
+	/*
+	 * Check VLF-bit which indicates the RTC data loss, such as due to a
+	 * supply voltage drop.
+	 */
+	i2c_readb(I2C_BUS_NUM, I2C_DEV_NUM, FLAG_REGISTER, &reg);
+
+	if (!(reg & VLF_BIT))
+		/* No voltage low detected, everything is well. */
+		return;
+
+	/*
+	 * Voltage low detected, initialize RX6110 SA again.
+	 * Set first some registers to known state.
+	 */
+	i2c_writeb(I2C_BUS_NUM, I2C_DEV_NUM, BATTERY_BACKUP_REG, 0x00);
+	i2c_writeb(I2C_BUS_NUM, I2C_DEV_NUM, RESERVED_BIT_REG, RTC_INIT_VALUE);
+	i2c_writeb(I2C_BUS_NUM, I2C_DEV_NUM, DIGITAL_REG, 0x00);
+	i2c_writeb(I2C_BUS_NUM, I2C_DEV_NUM, IRQ_CONTROL_REG, 0x00);
+
+	/* Clear timer enable bit and set frequency of clock output. */
+	i2c_readb(I2C_BUS_NUM, I2C_DEV_NUM, EXTENSION_REG, &reg);
+	reg &= ~(FSEL_MASK | TE_BIT);
+	reg |= (config->cof_selection << 6);
+	i2c_writeb(I2C_BUS_NUM, I2C_DEV_NUM, EXTENSION_REG, reg);
+
+	/* Clear voltage low detect bit. */
+	i2c_readb(I2C_BUS_NUM, I2C_DEV_NUM, FLAG_REGISTER, &reg);
+	reg &= ~VLF_BIT;
+	i2c_writeb(I2C_BUS_NUM, I2C_DEV_NUM, FLAG_REGISTER, reg);
+
+	/* Before setting the clock stop oscillator. */
+	i2c_writeb(I2C_BUS_NUM,	I2C_DEV_NUM, CTRL_REG, STOP_BIT);
+	if (config->set_user_date) {
+		/* Set user date defined in device tree. */
+		printk(BIOS_DEBUG, "%s: Set to user date\n",
+				dev->chip_ops->name);
+		rx6110sa_set_user_date(dev);
+	} else {
+		/* Set date from coreboot build. */
+		printk(BIOS_DEBUG, "%s: Set to coreboot build date\n",
+				dev->chip_ops->name);
+		rx6110sa_set_build_date(dev);
+	}
+	i2c_writeb(I2C_BUS_NUM, I2C_DEV_NUM, HOUR_REG, 1);
+	i2c_writeb(I2C_BUS_NUM, I2C_DEV_NUM, MINUTE_REG, 0);
+	i2c_writeb(I2C_BUS_NUM, I2C_DEV_NUM, SECOND_REG, 0);
+	/* Start oscillator again as the RTC is set up now. */
+	i2c_writeb(I2C_BUS_NUM,	I2C_DEV_NUM, CTRL_REG, 0x00);
+}
+
+static struct device_operations rx6110sa_ops = {
+	.read_resources		= DEVICE_NOOP,
+	.set_resources		= DEVICE_NOOP,
+	.enable_resources	= DEVICE_NOOP,
+	.init			= rx6110sa_init,
+	.final			= rx6110sa_final
+};
+
+static void rx6110sa_enable(struct device *dev)
+{
+	dev->ops = &rx6110sa_ops;
+}
+
+struct chip_operations drivers_i2c_rx6110sa_ops = {
+	CHIP_NAME("RX6110 SA")
+	.enable_dev = rx6110sa_enable
+};