rtc: add Intersil ISL12022 RTC driver

- derived from rtc-pcf8563

- no SRAM driver

Signed-off-by: Roman Fietze <roman.fietze@telemotive.de>
Cc: Wan ZongShun <mcuos.com@gmail.com>
Cc: Alessandro Zummo <a.zummo@towertech.it>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

3 files changed, 337 insertions, 0 deletions

diff --git a/drivers/rtc/Kconfig b/drivers/rtc/Kconfig
index 6ed5e7e7e79..999db51e6a5 100644
--- a/drivers/rtc/Kconfig
+++ b/drivers/rtc/Kconfig
@@ -203,6 +203,15 @@ config RTC_DRV_ISL1208
 	  This driver can also be built as a module. If so, the module
 	  will be called rtc-isl1208.
 
+config RTC_DRV_ISL12022
+	tristate "Intersil ISL12022"
+	help
+	  If you say yes here you get support for the
+	  Intersil ISL12022 RTC chip.
+
+	  This driver can also be built as a module. If so, the module
+	  will be called rtc-isl12022.
+
 config RTC_DRV_X1205
 	tristate "Xicor/Intersil X1205"
 	help
diff --git a/drivers/rtc/Makefile b/drivers/rtc/Makefile
index f58129906e1..e29b7f9377d 100644
--- a/drivers/rtc/Makefile
+++ b/drivers/rtc/Makefile
@@ -48,6 +48,7 @@ obj-$(CONFIG_RTC_DRV_FM3130)	+= rtc-fm3130.o
 obj-$(CONFIG_RTC_DRV_GENERIC)	+= rtc-generic.o
 obj-$(CONFIG_RTC_DRV_IMXDI)	+= rtc-imxdi.o
 obj-$(CONFIG_RTC_DRV_ISL1208)	+= rtc-isl1208.o
+obj-$(CONFIG_RTC_DRV_ISL12022)	+= rtc-isl12022.o
 obj-$(CONFIG_RTC_DRV_JZ4740)	+= rtc-jz4740.o
 obj-$(CONFIG_RTC_DRV_M41T80)	+= rtc-m41t80.o
 obj-$(CONFIG_RTC_DRV_M41T94)	+= rtc-m41t94.o
diff --git a/drivers/rtc/rtc-isl12022.c b/drivers/rtc/rtc-isl12022.c
new file mode 100644
index 00000000000..4a8c9dd12a7
--- /dev/null
+++ b/drivers/rtc/rtc-isl12022.c
@@ -0,0 +1,327 @@
+/*
+ * An I2C driver for the Intersil ISL 12022
+ *
+ * Author: Roman Fietze <roman.fietze@telemotive.de>
+ *
+ * Based on the Philips PCF8563 RTC
+ * by Alessandro Zummo <a.zummo@towertech.it>.
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License version
+ * 2 as published by the Free Software Foundation.
+ */
+
+#include <linux/i2c.h>
+#include <linux/bcd.h>
+#include <linux/rtc.h>
+#include <linux/slab.h>
+
+#define DRV_VERSION "0.1"
+
+/* ISL register offsets */
+#define ISL12022_REG_SC		0x00
+#define ISL12022_REG_MN		0x01
+#define ISL12022_REG_HR		0x02
+#define ISL12022_REG_DT		0x03
+#define ISL12022_REG_MO		0x04
+#define ISL12022_REG_YR		0x05
+#define ISL12022_REG_DW		0x06
+
+#define ISL12022_REG_SR		0x07
+#define ISL12022_REG_INT	0x08
+
+/* ISL register bits */
+#define ISL12022_HR_MIL		(1 << 7)	/* military or 24 hour time */
+
+#define ISL12022_SR_LBAT85	(1 << 2)
+#define ISL12022_SR_LBAT75	(1 << 1)
+
+#define ISL12022_INT_WRTC	(1 << 6)
+
+
+static struct i2c_driver isl12022_driver;
+
+struct isl12022 {
+	struct rtc_device *rtc;
+
+	bool write_enabled;	/* true if write enable is set */
+};
+
+
+static int isl12022_read_regs(struct i2c_client *client, uint8_t reg,
+			      uint8_t *data, size_t n)
+{
+	struct i2c_msg msgs[] = {
+		{
+			.addr	= client->addr,
+			.flags	= 0,
+			.len	= 1,
+			.buf	= data
+		},		/* setup read ptr */
+		{
+			.addr	= client->addr,
+			.flags	= I2C_M_RD,
+			.len	= n,
+			.buf	= data
+		}
+	};
+
+	int ret;
+
+	data[0] = reg;
+	ret = i2c_transfer(client->adapter, msgs, ARRAY_SIZE(msgs));
+	if (ret != ARRAY_SIZE(msgs)) {
+		dev_err(&client->dev, "%s: read error, ret=%d\n",
+			__func__, ret);
+		return -EIO;
+	}
+
+	return 0;
+}
+
+
+static int isl12022_write_reg(struct i2c_client *client,
+			      uint8_t reg, uint8_t val)
+{
+	uint8_t data[2] = { reg, val };
+	int err;
+
+	err = i2c_master_send(client, data, sizeof(data));
+	if (err != sizeof(data)) {
+		dev_err(&client->dev,
+			"%s: err=%d addr=%02x, data=%02x\n",
+			__func__, err, data[0], data[1]);
+		return -EIO;
+	}
+
+	return 0;
+}
+
+
+/*
+ * In the routines that deal directly with the isl12022 hardware, we use
+ * rtc_time -- month 0-11, hour 0-23, yr = calendar year-epoch.
+ */
+static int isl12022_get_datetime(struct i2c_client *client, struct rtc_time *tm)
+{
+	uint8_t buf[ISL12022_REG_INT + 1];
+	int ret;
+
+	ret = isl12022_read_regs(client, ISL12022_REG_SC, buf, sizeof(buf));
+	if (ret)
+		return ret;
+
+	if (buf[ISL12022_REG_SR] & (ISL12022_SR_LBAT85 | ISL12022_SR_LBAT75)) {
+		dev_warn(&client->dev,
+			 "voltage dropped below %u%%, "
+			 "date and time is not reliable.\n",
+			 buf[ISL12022_REG_SR] & ISL12022_SR_LBAT85 ? 85 : 75);
+	}
+
+	dev_dbg(&client->dev,
+		"%s: raw data is sec=%02x, min=%02x, hr=%02x, "
+		"mday=%02x, mon=%02x, year=%02x, wday=%02x, "
+		"sr=%02x, int=%02x",
+		__func__,
+		buf[ISL12022_REG_SC],
+		buf[ISL12022_REG_MN],
+		buf[ISL12022_REG_HR],
+		buf[ISL12022_REG_DT],
+		buf[ISL12022_REG_MO],
+		buf[ISL12022_REG_YR],
+		buf[ISL12022_REG_DW],
+		buf[ISL12022_REG_SR],
+		buf[ISL12022_REG_INT]);
+
+	tm->tm_sec = bcd2bin(buf[ISL12022_REG_SC] & 0x7F);
+	tm->tm_min = bcd2bin(buf[ISL12022_REG_MN] & 0x7F);
+	tm->tm_hour = bcd2bin(buf[ISL12022_REG_HR] & 0x3F);
+	tm->tm_mday = bcd2bin(buf[ISL12022_REG_DT] & 0x3F);
+	tm->tm_wday = buf[ISL12022_REG_DW] & 0x07;
+	tm->tm_mon = bcd2bin(buf[ISL12022_REG_MO] & 0x1F) - 1;
+	tm->tm_year = bcd2bin(buf[ISL12022_REG_YR]) + 100;
+
+	dev_dbg(&client->dev, "%s: secs=%d, mins=%d, hours=%d, "
+		"mday=%d, mon=%d, year=%d, wday=%d\n",
+		__func__,
+		tm->tm_sec, tm->tm_min, tm->tm_hour,
+		tm->tm_mday, tm->tm_mon, tm->tm_year, tm->tm_wday);
+
+	/* The clock can give out invalid datetime, but we cannot return
+	 * -EINVAL otherwise hwclock will refuse to set the time on bootup. */
+	if (rtc_valid_tm(tm) < 0)
+		dev_err(&client->dev, "retrieved date and time is invalid.\n");
+
+	return 0;
+}
+
+static int isl12022_set_datetime(struct i2c_client *client, struct rtc_time *tm)
+{
+	struct isl12022 *isl12022 = i2c_get_clientdata(client);
+	size_t i;
+	int ret;
+	uint8_t buf[ISL12022_REG_DW + 1];
+
+	dev_dbg(&client->dev, "%s: secs=%d, mins=%d, hours=%d, "
+		"mday=%d, mon=%d, year=%d, wday=%d\n",
+		__func__,
+		tm->tm_sec, tm->tm_min, tm->tm_hour,
+		tm->tm_mday, tm->tm_mon, tm->tm_year, tm->tm_wday);
+
+	if (!isl12022->write_enabled) {
+
+		ret = isl12022_read_regs(client, ISL12022_REG_INT, buf, 1);
+		if (ret)
+			return ret;
+
+		/* Check if WRTC (write rtc enable) is set factory default is
+		 * 0 (not set) */
+		if (!(buf[0] & ISL12022_INT_WRTC)) {
+			dev_info(&client->dev,
+				 "init write enable and 24 hour format\n");
+
+			/* Set the write enable bit. */
+			ret = isl12022_write_reg(client,
+						 ISL12022_REG_INT,
+						 buf[0] | ISL12022_INT_WRTC);
+			if (ret)
+				return ret;
+
+			/* Write to any RTC register to start RTC, we use the
+			 * HR register, setting the MIL bit to use the 24 hour
+			 * format. */
+			ret = isl12022_read_regs(client, ISL12022_REG_HR,
+						 buf, 1);
+			if (ret)
+				return ret;
+
+			ret = isl12022_write_reg(client,
+						 ISL12022_REG_HR,
+						 buf[0] | ISL12022_HR_MIL);
+			if (ret)
+				return ret;
+		}
+
+		isl12022->write_enabled = 1;
+	}
+
+	/* hours, minutes and seconds */
+	buf[ISL12022_REG_SC] = bin2bcd(tm->tm_sec);
+	buf[ISL12022_REG_MN] = bin2bcd(tm->tm_min);
+	buf[ISL12022_REG_HR] = bin2bcd(tm->tm_hour);
+
+	buf[ISL12022_REG_DT] = bin2bcd(tm->tm_mday);
+
+	/* month, 1 - 12 */
+	buf[ISL12022_REG_MO] = bin2bcd(tm->tm_mon + 1);
+
+	/* year and century */
+	buf[ISL12022_REG_YR] = bin2bcd(tm->tm_year % 100);
+
+	buf[ISL12022_REG_DW] = tm->tm_wday & 0x07;
+
+	/* write register's data */
+	for (i = 0; i < ARRAY_SIZE(buf); i++) {
+		ret = isl12022_write_reg(client, ISL12022_REG_SC + i,
+					 buf[ISL12022_REG_SC + i]);
+		if (ret)
+			return -EIO;
+	};
+
+	return 0;
+}
+
+static int isl12022_rtc_read_time(struct device *dev, struct rtc_time *tm)
+{
+	return isl12022_get_datetime(to_i2c_client(dev), tm);
+}
+
+static int isl12022_rtc_set_time(struct device *dev, struct rtc_time *tm)
+{
+	return isl12022_set_datetime(to_i2c_client(dev), tm);
+}
+
+static const struct rtc_class_ops isl12022_rtc_ops = {
+	.read_time	= isl12022_rtc_read_time,
+	.set_time	= isl12022_rtc_set_time,
+};
+
+static int isl12022_probe(struct i2c_client *client,
+			  const struct i2c_device_id *id)
+{
+	struct isl12022 *isl12022;
+
+	int ret = 0;
+
+	if (!i2c_check_functionality(client->adapter, I2C_FUNC_I2C))
+		return -ENODEV;
+
+	isl12022 = kzalloc(sizeof(struct isl12022), GFP_KERNEL);
+	if (!isl12022)
+		return -ENOMEM;
+
+	dev_dbg(&client->dev, "chip found, driver version " DRV_VERSION "\n");
+
+	i2c_set_clientdata(client, isl12022);
+
+	isl12022->rtc = rtc_device_register(isl12022_driver.driver.name,
+					    &client->dev,
+					    &isl12022_rtc_ops,
+					    THIS_MODULE);
+
+	if (IS_ERR(isl12022->rtc)) {
+		ret = PTR_ERR(isl12022->rtc);
+		goto exit_kfree;
+	}
+
+	return 0;
+
+exit_kfree:
+	kfree(isl12022);
+
+	return ret;
+}
+
+static int isl12022_remove(struct i2c_client *client)
+{
+	struct isl12022 *isl12022 = i2c_get_clientdata(client);
+
+	rtc_device_unregister(isl12022->rtc);
+	kfree(isl12022);
+
+	return 0;
+}
+
+static const struct i2c_device_id isl12022_id[] = {
+	{ "isl12022", 0 },
+	{ "rtc8564", 0 },
+	{ }
+};
+MODULE_DEVICE_TABLE(i2c, isl12022_id);
+
+static struct i2c_driver isl12022_driver = {
+	.driver		= {
+		.name	= "rtc-isl12022",
+	},
+	.probe		= isl12022_probe,
+	.remove		= isl12022_remove,
+	.id_table	= isl12022_id,
+};
+
+static int __init isl12022_init(void)
+{
+	return i2c_add_driver(&isl12022_driver);
+}
+
+static void __exit isl12022_exit(void)
+{
+	i2c_del_driver(&isl12022_driver);
+}
+
+module_init(isl12022_init);
+module_exit(isl12022_exit);
+
+MODULE_AUTHOR("roman.fietze@telemotive.de");
+MODULE_DESCRIPTION("ISL 12022 RTC driver");
+MODULE_LICENSE("GPL");
+MODULE_VERSION(DRV_VERSION);