[RFC][PATCH 6/7] RTC subsystem, x1205 driver

[Alessandro Zummo]

This patch is a port of the existing x1205
driver under the new RTC subsystem.

It is actually under test within the NSLU2
project (http://www.nslu2-linux.org) and
it is working quite well.

It is the first driver under this new subsystem
and should be used as a guide to port other
drivers.

Ideally, at some point in the future, all
RTC drivers will reside under linux/rtc.

Signed-off-by: Alessandro Zummo <a.zummo@xxxxxxxxxxxx>
--

 drivers/rtc/Kconfig     |   10 
 drivers/rtc/Makefile    |    3 
 drivers/rtc/rtc-x1205.c |  727 ++++++++++++++++++++++++++++++++++++++++++++++++
 3 files changed, 740 insertions(+)

--- linux.orig/drivers/rtc/Kconfig	2005-12-26 19:33:32.000000000 +0100
+++ linux/drivers/rtc/Kconfig	2005-12-26 19:35:01.000000000 +0100
@@ -55,4 +55,14 @@
 comment "RTC drivers"
 	depends on RTC_CLASS
 
+config RTC_DRV_X1205
+	tristate "Xicor/Intersil X1205 RTC chip"
+	depends on RTC_CLASS && I2C
+	help
+	  If you say yes here you get support for the
+	  Xicor/Intersil X1205 RTC chip.
+
+	  This driver can also be built as a module. If so, the module
+	  will be called rtc-x1205.
+
 endmenu
--- linux.orig/drivers/rtc/Makefile	2005-12-26 19:33:32.000000000 +0100
+++ linux/drivers/rtc/Makefile	2005-12-26 19:35:01.000000000 +0100
@@ -8,3 +8,6 @@
 obj-$(CONFIG_RTC_INTF_SYSFS)	+= rtc-sysfs.o
 obj-$(CONFIG_RTC_INTF_PROC)	+= rtc-proc.o
 obj-$(CONFIG_RTC_INTF_DEV)	+= rtc-dev.o
+
+obj-$(CONFIG_RTC_DRV_X1205)	+= rtc-x1205.o
+
--- /dev/null	1970-01-01 00:00:00.000000000 +0000
+++ linux/drivers/rtc/rtc-x1205.c	2005-12-26 19:33:46.000000000 +0100
@@ -0,0 +1,727 @@
+/*
+ * An i2c driver for the Xicor/Intersil X1205 RTC
+ * Copyright 2004 Karen Spearel
+ * Copyright 2005 Alessandro Zummo
+ *
+ * please send all reports to:
+ *	kas11 at tampabay dot rr dot com
+ *	a dot zummo at towertech dot it
+ *
+ * based on a lot of other RTC drivers.
+ *
+ * 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; either version 2 of the License, or
+ * (at your option) any later version.
+ */
+
+#include <linux/module.h>
+#include <linux/init.h>
+#include <linux/slab.h>
+#include <linux/err.h>
+#include <linux/i2c.h>
+#include <linux/string.h>
+#include <linux/bcd.h>
+#include <linux/rtc.h>
+#include <linux/delay.h>
+
+#define DRV_VERSION "1.0.5"
+
+/* Addresses to scan: none. This chip is located at
+ * 0x6f and uses a two bytes register addressing.
+ * Two bytes need to be written to read a single register,
+ * while most other chips just require one and take the second
+ * one as the data to be written. To prevent corrupting
+ * unknown chips, the user must explicitely set the probe parameter.
+ */
+
+static unsigned short normal_i2c[] = { I2C_CLIENT_END };
+
+/* Insmod parameters */
+I2C_CLIENT_INSMOD;
+I2C_CLIENT_MODULE_PARM(hctosys,
+	"Set the system time from the hardware clock upon initialization");
+
+/* offsets into CCR area */
+
+#define CCR_SEC			0
+#define CCR_MIN			1
+#define CCR_HOUR		2
+#define CCR_MDAY		3
+#define CCR_MONTH		4
+#define CCR_YEAR		5
+#define CCR_WDAY		6
+#define CCR_Y2K			7
+
+#define X1205_REG_SR		0x3F	/* status register */
+#define X1205_REG_Y2K		0x37
+#define X1205_REG_DW		0x36
+#define X1205_REG_YR		0x35
+#define X1205_REG_MO		0x34
+#define X1205_REG_DT		0x33
+#define X1205_REG_HR		0x32
+#define X1205_REG_MN		0x31
+#define X1205_REG_SC		0x30
+#define X1205_REG_DTR		0x13
+#define X1205_REG_ATR		0x12
+#define X1205_REG_INT		0x11
+#define X1205_REG_0		0x10
+#define X1205_REG_Y2K1		0x0F
+#define X1205_REG_DWA1		0x0E
+#define X1205_REG_YRA1		0x0D
+#define X1205_REG_MOA1		0x0C
+#define X1205_REG_DTA1		0x0B
+#define X1205_REG_HRA1		0x0A
+#define X1205_REG_MNA1		0x09
+#define X1205_REG_SCA1		0x08
+#define X1205_REG_Y2K0		0x07
+#define X1205_REG_DWA0		0x06
+#define X1205_REG_YRA0		0x05
+#define X1205_REG_MOA0		0x04
+#define X1205_REG_DTA0		0x03
+#define X1205_REG_HRA0		0x02
+#define X1205_REG_MNA0		0x01
+#define X1205_REG_SCA0		0x00
+
+#define X1205_CCR_BASE		0x30	/* Base address of CCR */
+#define X1205_ALM0_BASE		0x00	/* Base address of ALARM0 */
+
+#define X1205_SR_RTCF		0x01	/* Clock failure */
+#define X1205_SR_WEL		0x02	/* Write Enable Latch */
+#define X1205_SR_RWEL		0x04	/* Register Write Enable */
+
+#define X1205_DTR_DTR0		0x01
+#define X1205_DTR_DTR1		0x02
+#define X1205_DTR_DTR2		0x04
+
+#define X1205_HR_MIL		0x80	/* Set in ccr.hour for 24 hr mode */
+
+/* Prototypes */
+static int x1205_attach(struct i2c_adapter *adapter);
+static int x1205_detach(struct i2c_client *client);
+static int x1205_probe(struct i2c_adapter *adapter, int address, int kind);
+
+static struct i2c_driver x1205_driver = {
+	.owner		= THIS_MODULE,
+	.name		= "x1205",
+	.flags		= I2C_DF_NOTIFY,
+	.attach_adapter = &x1205_attach,
+	.detach_client	= &x1205_detach,
+};
+
+/*
+ * In the routines that deal directly with the x1205 hardware, we use
+ * rtc_time -- month 0-11, hour 0-23, yr = calendar year-epoch
+ * Epoch is initialized as 2000. Time is set to UTC.
+ */
+static int x1205_get_datetime(struct i2c_client *client, struct rtc_time *tm,
+				unsigned char reg_base)
+{
+	unsigned char dt_addr[2] = { 0, reg_base };
+
+	unsigned char buf[8];
+
+	struct i2c_msg msgs[] = {
+		{ client->addr, 0, 2, dt_addr },	/* setup read ptr */
+		{ client->addr, I2C_M_RD, 8, buf },	/* read date */
+	};
+
+	/* read date registers */
+	if ((i2c_transfer(client->adapter, &msgs[0], 2)) != 2) {
+		dev_err(&client->dev, "%s: read error\n", __FUNCTION__);
+		return -EIO;
+	}
+
+	dev_dbg(&client->dev,
+		"%s: raw read data - sec=%02x, min=%02x, hr=%02x, "
+		"mday=%02x, mon=%02x, year=%02x, wday=%02x, y2k=%02x\n",
+		__FUNCTION__,
+		buf[0], buf[1], buf[2], buf[3],
+		buf[4], buf[5], buf[6], buf[7]);
+
+	tm->tm_sec = BCD2BIN(buf[CCR_SEC]);
+	tm->tm_min = BCD2BIN(buf[CCR_MIN]);
+	tm->tm_hour = BCD2BIN(buf[CCR_HOUR] & 0x3F); /* hr is 0-23 */
+	tm->tm_mday = BCD2BIN(buf[CCR_MDAY]);
+	tm->tm_mon = BCD2BIN(buf[CCR_MONTH]) - 1; /* mon is 0-11 */
+	tm->tm_year = BCD2BIN(buf[CCR_YEAR])
+			+ (BCD2BIN(buf[CCR_Y2K]) * 100) - 1900;
+	tm->tm_wday = buf[CCR_WDAY];
+
+	dev_dbg(&client->dev, "%s: tm is secs=%d, mins=%d, hours=%d, "
+		"mday=%d, mon=%d, year=%d, wday=%d\n",
+		__FUNCTION__,
+		tm->tm_sec, tm->tm_min, tm->tm_hour,
+		tm->tm_mday, tm->tm_mon, tm->tm_year, tm->tm_wday);
+
+	return 0;
+}
+
+static int x1205_get_status(struct i2c_client *client, unsigned char *sr)
+{
+	static unsigned char sr_addr[2] = { 0, X1205_REG_SR };
+
+	struct i2c_msg msgs[] = {
+		{ client->addr, 0, 2, sr_addr },	/* setup read ptr */
+		{ client->addr, I2C_M_RD, 1, sr },	/* read status */
+	};
+
+	/* read status register */
+	if ((i2c_transfer(client->adapter, &msgs[0], 2)) != 2) {
+		dev_err(&client->dev, "%s: read error\n", __FUNCTION__);
+		return -EIO;
+	}
+
+	return 0;
+}
+
+static int x1205_set_datetime(struct i2c_client *client, struct rtc_time *tm,
+				int datetoo, u8 reg_base)
+{
+	int i, xfer;
+	unsigned char buf[8];
+
+	static const unsigned char wel[3] = { 0, X1205_REG_SR,
+						X1205_SR_WEL };
+
+	static const unsigned char rwel[3] = { 0, X1205_REG_SR,
+						X1205_SR_WEL | X1205_SR_RWEL };
+
+	static const unsigned char diswe[3] = { 0, X1205_REG_SR, 0 };
+
+	dev_dbg(&client->dev,
+		"%s: secs=%d, mins=%d, hours=%d\n",
+		__FUNCTION__,
+		tm->tm_sec, tm->tm_min, tm->tm_hour);
+
+	buf[CCR_SEC] = BIN2BCD(tm->tm_sec);
+	buf[CCR_MIN] = BIN2BCD(tm->tm_min);
+
+	/* set hour and 24hr bit */
+	buf[CCR_HOUR] = BIN2BCD(tm->tm_hour) | X1205_HR_MIL;
+
+	/* should we also set the date? */
+	if (datetoo) {
+		dev_dbg(&client->dev,
+			"%s: mday=%d, mon=%d, year=%d, wday=%d\n",
+			__FUNCTION__,
+			tm->tm_mday, tm->tm_mon, tm->tm_year, tm->tm_wday);
+
+		buf[CCR_MDAY] = BIN2BCD(tm->tm_mday);
+
+		/* month, 1 - 12 */
+		buf[CCR_MONTH] = BIN2BCD(tm->tm_mon + 1);
+
+		/* year, since the rtc epoch*/
+		buf[CCR_YEAR] = BIN2BCD(tm->tm_year % 100);
+		buf[CCR_WDAY] = tm->tm_wday & 0x07;
+		buf[CCR_Y2K] = BIN2BCD(tm->tm_year / 100);
+	}
+
+	/* this sequence is required to unlock the chip */
+	xfer = i2c_master_send(client, wel, 3);
+	if (xfer != 3) {
+		dev_err(&client->dev, "%s: wel - %d\n", __FUNCTION__, xfer);
+		return -EIO;
+	}
+
+	xfer = i2c_master_send(client, rwel, 3);
+	if (xfer != 3) {
+		dev_err(&client->dev, "%s: rwel - %d\n", __FUNCTION__, xfer);
+		return -EIO;
+	}
+
+	/* write register's data */
+	for (i = 0; i < (datetoo ? 8 : 3); i++) {
+		unsigned char rdata[3] = { 0, reg_base + i, buf[i] };
+
+		xfer = i2c_master_send(client, rdata, 3);
+		if (xfer != 3) {
+			dev_err(&client->dev,
+				"%s: xfer=%d addr=%02x, data=%02x\n",
+				__FUNCTION__,
+				 xfer, rdata[1], rdata[2]);
+			return -EIO;
+		}
+	};
+
+	/* disable further writes */
+	xfer = i2c_master_send(client, diswe, 3);
+	if (xfer != 3) {
+		dev_err(&client->dev, "%s: diswe - %d\n", __FUNCTION__, xfer);
+		return -EIO;
+	}
+
+	return 0;
+}
+
+static int x1205_fix_osc(struct i2c_client *client)
+{
+	int err;
+	struct rtc_time tm;
+
+	tm.tm_hour = 0;
+	tm.tm_min = 0;
+	tm.tm_sec = 0;
+
+	if ((err = x1205_set_datetime(client, &tm, 0, X1205_CCR_BASE)) < 0)
+		dev_err(&client->dev,
+			"unable to restart the clock\n");
+
+	return err;
+}
+
+static int x1205_get_dtrim(struct i2c_client *client, int *trim)
+{
+	unsigned char dtr;
+	static unsigned char dtr_addr[2] = { 0, X1205_REG_DTR };
+
+	struct i2c_msg msgs[] = {
+		{ client->addr, 0, 2, dtr_addr },	/* setup read ptr */
+		{ client->addr, I2C_M_RD, 1, &dtr }, 	/* read dtr */
+	};
+
+	/* read dtr register */
+	if ((i2c_transfer(client->adapter, &msgs[0], 2)) != 2) {
+		dev_err(&client->dev, "%s: read error\n", __FUNCTION__);
+		return -EIO;
+	}
+
+	dev_dbg(&client->dev, "%s: raw dtr=%x\n", __FUNCTION__, dtr);
+
+	*trim = 0;
+
+	if (dtr & X1205_DTR_DTR0)
+		*trim += 20;
+
+	if (dtr & X1205_DTR_DTR1)
+		*trim += 10;
+
+	if (dtr & X1205_DTR_DTR2)
+		*trim = -*trim;
+
+	return 0;
+}
+
+static int x1205_get_atrim(struct i2c_client *client, int *trim)
+{
+	s8 atr;
+	static unsigned char atr_addr[2] = { 0, X1205_REG_ATR };
+
+	struct i2c_msg msgs[] = {
+		{ client->addr, 0, 2, atr_addr },	/* setup read ptr */
+		{ client->addr, I2C_M_RD, 1, &atr }, 	/* read atr */
+	};
+
+	/* read atr register */
+	if ((i2c_transfer(client->adapter, &msgs[0], 2)) != 2) {
+		dev_err(&client->dev, "%s: read error\n", __FUNCTION__);
+		return -EIO;
+	}
+
+	dev_dbg(&client->dev, "%s: raw atr=%x\n", __FUNCTION__, atr);
+
+	/* atr is a two's complement value on 6 bits,
+	 * perform sign extension. The formula is
+	 * Catr = (atr * 0.25pF) + 11.00pF.
+	 */
+	if (atr & 0x20)
+		atr |= 0xC0;
+
+	dev_dbg(&client->dev, "%s: raw atr=%x (%d)\n", __FUNCTION__, atr, atr);
+
+	*trim = (atr * 250) + 11000;
+
+	dev_dbg(&client->dev, "%s: real=%d\n", __FUNCTION__, *trim);
+
+	return 0;
+}
+
+static int x1205_hctosys(struct i2c_client *client)
+{
+	int err;
+
+	struct rtc_time tm;
+	struct timespec tv;
+	unsigned char sr;
+
+	if ((err = x1205_get_status(client, &sr)) < 0)
+		return err;
+
+	/* Don't set if we had a power failure */
+	if (sr & X1205_SR_RTCF)
+		return -EINVAL;
+
+	if ((err = x1205_get_datetime(client, &tm, X1205_CCR_BASE)) < 0)
+		return err;
+
+	/* IMPORTANT: the RTC only stores whole seconds. It is arbitrary
+	 * whether it stores the most close value or the value with partial
+	 * seconds truncated. However, it is important that we use it to store
+	 * the truncated value. This is because otherwise it is necessary,
+	 * in an rtc sync function, to read both xtime.tv_sec and
+	 * xtime.tv_nsec. On some processors (i.e. ARM), an atomic read
+	 * of >32bits is not possible. So storing the most close value would
+	 * slow down the sync API. So here we have the truncated value and
+	 * the best guess is to add 0.5s.
+	 */
+
+	tv.tv_nsec = NSEC_PER_SEC >> 1;
+
+	rtc_tm_to_time(&tm, &tv.tv_sec);
+
+	do_settimeofday(&tv);
+
+	dev_info(&client->dev,
+		"setting the system clock to %d-%d-%d %d:%d:%d\n",
+		tm.tm_year + 1900, tm.tm_mon + 1,
+		tm.tm_mday, tm.tm_hour, tm.tm_min,
+		tm.tm_sec);
+
+	return 0;
+}
+
+struct x1205_limit
+{
+	unsigned char reg;
+	unsigned char mask;
+	unsigned char min;
+	unsigned char max;
+};
+
+static int x1205_validate_client(struct i2c_client *client)
+{
+	int i, xfer;
+
+	/* Probe array. We will read the register at the specified
+	 * address and check if the given bits are zero.
+	 */
+	static const unsigned char probe_zero_pattern[] = {
+		/* register, mask */
+		X1205_REG_SR,	0x18,
+		X1205_REG_DTR,	0xF8,
+		X1205_REG_ATR,	0xC0,
+		X1205_REG_INT,	0x18,
+		X1205_REG_0,	0xFF,
+	};
+
+	static const struct x1205_limit probe_limits_pattern[] = {
+		/* register, mask, min, max */
+		{ X1205_REG_Y2K,	0xFF,	19,	20	},
+		{ X1205_REG_DW,		0xFF,	0,	6	},
+		{ X1205_REG_YR,		0xFF,	0,	99	},
+		{ X1205_REG_MO,		0xFF,	0,	12	},
+		{ X1205_REG_DT,		0xFF,	0,	31	},
+		{ X1205_REG_HR,		0x7F,	0,	23	},
+		{ X1205_REG_MN,		0xFF,	0,	59	},
+		{ X1205_REG_SC,		0xFF,	0,	59	},
+		{ X1205_REG_Y2K1,	0xFF,	19,	20	},
+		{ X1205_REG_Y2K0,	0xFF,	19,	20	},
+	};
+
+	/* check that registers have bits a 0 where expected */
+	for (i = 0; i < ARRAY_SIZE(probe_zero_pattern); i += 2) {
+		unsigned char buf;
+
+		unsigned char addr[2] = { 0, probe_zero_pattern[i] };
+
+		struct i2c_msg msgs[2] = {
+			{ client->addr, 0, 2, addr },
+			{ client->addr, I2C_M_RD, 1, &buf },
+		};
+
+		xfer = i2c_transfer(client->adapter, msgs, 2);
+		if (xfer != 2) {
+			dev_err(&client->adapter->dev,
+				"%s: could not read register %x\n",
+				__FUNCTION__, addr[1]);
+
+			return -EIO;
+		}
+
+		if ((buf & probe_zero_pattern[i+1]) != 0) {
+			dev_err(&client->adapter->dev,
+				"%s: register=%02x, zero pattern=%d, value=%x\n",
+				__FUNCTION__, addr[1], i, buf);
+
+			return -ENODEV;
+		}
+	}
+
+	/* check limits (only registers with bcd values) */
+	for (i = 0; i < ARRAY_SIZE(probe_limits_pattern); i++) {
+		unsigned char reg, value;
+
+		unsigned char addr[2] = { 0, probe_limits_pattern[i].reg };
+
+		struct i2c_msg msgs[2] = {
+			{ client->addr, 0, 2, addr },
+			{ client->addr, I2C_M_RD, 1, &reg },
+		};
+
+		xfer = i2c_transfer(client->adapter, msgs, 2);
+
+		if (xfer != 2) {
+			dev_err(&client->adapter->dev,
+				"%s: could not read register %x\n",
+				__FUNCTION__, addr[1]);
+
+			return -EIO;
+		}
+
+		value = BCD2BIN(reg & probe_limits_pattern[i].mask);
+
+		if (value > probe_limits_pattern[i].max ||
+			value < probe_limits_pattern[i].min) {
+			dev_dbg(&client->adapter->dev,
+				"%s: register=%x, lim pattern=%d, value=%d\n",
+				__FUNCTION__, addr[1], i, value);
+
+			return -ENODEV;
+		}
+	}
+
+	return 0;
+}
+
+static int x1205_rtc_read_alarm(struct device *dev,
+	struct rtc_wkalrm *alrm)
+{
+	return x1205_get_datetime(to_i2c_client(dev),
+		&alrm->time, X1205_ALM0_BASE);
+}
+
+static int x1205_rtc_set_alarm(struct device *dev,
+	struct rtc_wkalrm *alrm)
+{
+	return x1205_set_datetime(to_i2c_client(dev),
+		&alrm->time, 1, X1205_ALM0_BASE);
+}
+
+static int x1205_rtc_read_time(struct device *dev,
+	struct rtc_time *tm)
+{
+	return x1205_get_datetime(to_i2c_client(dev),
+		tm, X1205_CCR_BASE);
+}
+
+static int x1205_rtc_set_time(struct device *dev,
+	struct rtc_time *tm)
+{
+	if ((rtc_valid_tm(tm)) < 0)
+		return -EINVAL;
+
+	return x1205_set_datetime(to_i2c_client(dev),
+		tm, 1, X1205_CCR_BASE);
+}
+
+static int x1205_rtc_set_mmss(struct device *dev, unsigned long secs)
+{
+	int err;
+
+	struct rtc_time new_tm, old_tm;
+
+	if ((err = x1205_rtc_read_time(dev, &old_tm) == 0))
+		return err;
+
+	/* FIXME      xtime.tv_nsec = old_tm.tm_sec * 10000000; */
+	new_tm.tm_sec  = secs % 60;
+	secs /= 60;
+	new_tm.tm_min  = secs % 60;
+	secs /= 60;
+	new_tm.tm_hour = secs % 24;
+
+       /*
+	* avoid writing when we're going to change the day
+	* of the month.  We will retry in the next minute.
+	* This basically means that if the RTC must not drift
+	* by more than 1 minute in 11 minutes.
+	*/
+	if ((old_tm.tm_hour == 23 && old_tm.tm_min == 59) ||
+	    (new_tm.tm_hour == 23 && new_tm.tm_min == 59))
+		return 1;
+
+	return x1205_rtc_set_time(dev, &new_tm);
+}
+
+static int x1205_rtc_proc(struct device *dev, struct seq_file *seq)
+{
+	int err, dtrim, atrim;
+
+	seq_printf(seq, "24hr\t\t: yes\n");
+
+	err = x1205_get_dtrim(to_i2c_client(dev), &dtrim);
+	if (err == 0)
+		seq_printf(seq, "digital_trim\t: %d ppm\n", dtrim);
+
+	err = x1205_get_atrim(to_i2c_client(dev), &atrim);
+	if (err == 0)
+		seq_printf(seq, "analog_trim\t: %d.%02d pF\n",
+			atrim / 1000, atrim % 1000);
+	return 0;
+}
+
+static struct rtc_class_ops x1205_rtc_ops = {
+	.owner = THIS_MODULE,
+	.proc = x1205_rtc_proc,
+	.read_time = x1205_rtc_read_time,
+	.set_time = x1205_rtc_set_time,
+	.read_alarm = x1205_rtc_read_alarm,
+	.set_alarm = x1205_rtc_set_alarm,
+	.set_mmss = x1205_rtc_set_mmss,
+};
+
+static ssize_t x1205_sysfs_show_atrim(struct device *dev,
+				struct device_attribute *attr, char *buf)
+{
+	int atrim;
+
+        if (x1205_get_atrim(to_i2c_client(dev), &atrim) == 0) {
+                return sprintf(buf, "%d.%02d pF\n",
+                        atrim / 1000, atrim % 1000);        }
+        return 0;
+}
+static DEVICE_ATTR(atrim, S_IRUGO, x1205_sysfs_show_atrim, NULL);
+
+static ssize_t x1205_sysfs_show_dtrim(struct device *dev,
+				struct device_attribute *attr, char *buf)
+{
+	int dtrim;
+
+        if (x1205_get_dtrim(to_i2c_client(dev), &dtrim) == 0) {
+                return sprintf(buf, "%d ppm\n", dtrim);
+        }
+        return 0;
+}
+static DEVICE_ATTR(dtrim, S_IRUGO, x1205_sysfs_show_dtrim, NULL);
+
+
+static int x1205_attach(struct i2c_adapter *adapter)
+{
+	dev_dbg(&adapter->dev, "%s\n", __FUNCTION__);
+
+	return i2c_probe(adapter, &addr_data, x1205_probe);
+}
+
+static int x1205_probe(struct i2c_adapter *adapter, int address, int kind)
+{
+	int err = 0;
+	unsigned char sr;
+	struct i2c_client *client;
+	struct rtc_device *rtc_dev;
+
+	dev_dbg(&adapter->dev, "%s\n", __FUNCTION__);
+
+	if (!i2c_check_functionality(adapter, I2C_FUNC_I2C)) {
+		err = -ENODEV;
+		goto exit;
+	}
+
+	if (!(client = kzalloc(sizeof(struct i2c_client), GFP_KERNEL))) {
+		err = -ENOMEM;
+		goto exit;
+	}
+
+	/* I2C client */
+	client->addr = address;
+	client->driver = &x1205_driver;
+	client->adapter	= adapter;
+
+	strlcpy(client->name, "x1205", I2C_NAME_SIZE);
+
+	/* Verify the chip is really an X1205 */
+	if (kind < 0) {
+		if (x1205_validate_client(client) < 0) {
+			err = -ENODEV;
+			goto exit_kfree;
+		}
+	}
+
+	/* Inform the i2c layer */
+	if ((err = i2c_attach_client(client)))
+		goto exit_kfree;
+
+	dev_info(&client->dev, "chip found, driver version " DRV_VERSION "\n");
+
+	rtc_dev = rtc_device_register(&client->dev, &x1205_rtc_ops);
+	if (IS_ERR(rtc_dev)) {
+		err = PTR_ERR(rtc_dev);
+		dev_err(&client->dev,
+			"unable to register the class device\n");
+		goto exit_detach;
+	}
+
+	i2c_set_clientdata(client, rtc_dev);
+
+	/* Check for power failures and eventualy enable the osc */
+	if ((err = x1205_get_status(client, &sr)) == 0) {
+		if (sr & X1205_SR_RTCF) {
+			dev_err(&client->dev,
+				"power failure detected, "
+				"please set the clock\n");
+			udelay(50);
+			x1205_fix_osc(client);
+		}
+	}
+	else
+		dev_err(&client->dev, "couldn't read status\n");
+
+	/* If requested, set the system time */
+	if (hctosys) {
+		if ((err = x1205_hctosys(client)) < 0)
+			dev_err(&client->dev,
+				"unable to set the system clock\n");
+	}
+
+	device_create_file(&client->dev, &dev_attr_atrim);
+	device_create_file(&client->dev, &dev_attr_dtrim);
+
+	return 0;
+
+exit_detach:
+	i2c_detach_client(client);
+
+exit_kfree:
+	kfree(client);
+
+exit:
+	return err;
+}
+
+static int x1205_detach(struct i2c_client *client)
+{
+	int err;
+	struct rtc_device *rtc_dev = i2c_get_clientdata(client);
+
+	dev_dbg(&client->dev, "%s\n", __FUNCTION__);
+
+ 	if (rtc_dev)
+		rtc_device_unregister(rtc_dev);
+
+	if ((err = i2c_detach_client(client)))
+		return err;
+
+	kfree(client);
+
+	return 0;
+}
+
+static int __init x1205_init(void)
+{
+	return i2c_add_driver(&x1205_driver);
+}
+
+static void __exit x1205_exit(void)
+{
+	i2c_del_driver(&x1205_driver);
+}
+
+MODULE_AUTHOR(
+	"Karen Spearel <kas11@xxxxxxxxxxxxxxx>, "
+	"Alessandro Zummo <a.zummo@xxxxxxxxxxxx>");
+MODULE_DESCRIPTION("Xicor/Intersil X1205 RTC driver");
+MODULE_LICENSE("GPL");
+MODULE_VERSION(DRV_VERSION);
+
+module_init(x1205_init);
+module_exit(x1205_exit);
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