hwmon: add support for JEDEC JC 42.4 compliant temperature sensors

[akpm@linux-foundation.org: coding-style fixes]
Signed-off-by: Guenter Roeck <guenter.roeck@ericsson.com>
Cc: Jean Delvare <khali@linux-fr.org>
Cc: Randy Dunlap <rdunlap@xenotime.net>
Cc: Hans de Goede <hdegoede@redhat.com>
Cc: Mark Brown <broonie@opensource.wolfsonmicro.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

5 files changed, 709 insertions, 0 deletions

diff --git a/Documentation/hwmon/jc42 b/Documentation/hwmon/jc42
new file mode 100644
index 00000000000..0e76ef12e4c
--- /dev/null
+++ b/Documentation/hwmon/jc42
@@ -0,0 +1,97 @@
+Kernel driver jc42
+==================
+
+Supported chips:
+  * Analog Devices ADT7408
+    Prefix: 'adt7408'
+    Addresses scanned: I2C 0x18 - 0x1f
+    Datasheets:
+	http://www.analog.com/static/imported-files/data_sheets/ADT7408.pdf
+  * IDT TSE2002B3, TS3000B3
+    Prefix: 'tse2002b3', 'ts3000b3'
+    Addresses scanned: I2C 0x18 - 0x1f
+    Datasheets:
+	http://www.idt.com/products/getdoc.cfm?docid=18715691
+	http://www.idt.com/products/getdoc.cfm?docid=18715692
+  * Maxim MAX6604
+    Prefix: 'max6604'
+    Addresses scanned: I2C 0x18 - 0x1f
+    Datasheets:
+	http://datasheets.maxim-ic.com/en/ds/MAX6604.pdf
+  * Microchip MCP9805, MCP98242, MCP98243, MCP9843
+    Prefixes: 'mcp9805', 'mcp98242', 'mcp98243', 'mcp9843'
+    Addresses scanned: I2C 0x18 - 0x1f
+    Datasheets:
+	http://ww1.microchip.com/downloads/en/DeviceDoc/21977b.pdf
+	http://ww1.microchip.com/downloads/en/DeviceDoc/21996a.pdf
+	http://ww1.microchip.com/downloads/en/DeviceDoc/22153c.pdf
+  * NXP Semiconductors SE97, SE97B
+    Prefix: 'se97'
+    Addresses scanned: I2C 0x18 - 0x1f
+    Datasheets:
+	http://www.nxp.com/documents/data_sheet/SE97.pdf
+	http://www.nxp.com/documents/data_sheet/SE97B.pdf
+  * NXP Semiconductors SE98
+    Prefix: 'se98'
+    Addresses scanned: I2C 0x18 - 0x1f
+    Datasheets:
+	http://www.nxp.com/documents/data_sheet/SE98.pdf
+  * ON Semiconductor CAT34TS02, CAT6095
+    Prefix: 'cat34ts02', 'cat6095'
+    Addresses scanned: I2C 0x18 - 0x1f
+    Datasheet:
+	http://www.onsemi.com/pub_link/Collateral/CAT34TS02-D.PDF
+	http://www.onsemi.com/pub/Collateral/CAT6095-D.PDF
+  * ST Microelectronics STTS424, STTS424E02
+    Prefix: 'stts424'
+    Addresses scanned: I2C 0x18 - 0x1f
+    Datasheets:
+	http://www.st.com/stonline/products/literature/ds/13447/stts424.pdf
+	http://www.st.com/stonline/products/literature/ds/13448/stts424e02.pdf
+  * JEDEC JC 42.4 compliant temperature sensor chips
+    Prefix: 'jc42'
+    Addresses scanned: I2C 0x18 - 0x1f
+    Datasheet: -
+
+Author:
+	Guenter Roeck <guenter.roeck@ericsson.com>
+
+
+Description
+-----------
+
+This driver implements support for JEDEC JC 42.4 compliant temperature sensors.
+The driver auto-detects the chips listed above, but can be manually instantiated
+to support other JC 42.4 compliant chips.
+
+Example: the following will load the driver for a generic JC 42.4 compliant
+temperature sensor at address 0x18 on I2C bus #1:
+
+# modprobe jc42
+# echo jc42 0x18 > /sys/bus/i2c/devices/i2c-1/new_device
+
+A JC 42.4 compliant chip supports a single temperature sensor. Minimum, maximum,
+and critical temperature can be configured. There are alarms for high, low,
+and critical thresholds.
+
+There is also an hysteresis to control the thresholds for resetting alarms.
+Per JC 42.4 specification, the hysteresis threshold can be configured to 0, 1.5,
+3.0, and 6.0 degrees C. Configured hysteresis values will be rounded to those
+limits. The chip supports only a single register to configure the hysteresis,
+which applies to all limits. This register can be written by writing into
+temp1_crit_hyst. Other hysteresis attributes are read-only.
+
+Sysfs entries
+-------------
+
+temp1_input		Temperature (RO)
+temp1_min		Minimum temperature (RW)
+temp1_max		Maximum temperature (RW)
+temp1_crit		Critical high temperature (RW)
+
+temp1_crit_hyst		Critical hysteresis temperature (RW)
+temp1_max_hyst		Maximum hysteresis temperature (RO)
+
+temp1_min_alarm		Temperature low alarm
+temp1_max_alarm		Temperature high alarm
+temp1_crit_alarm	Temperature critical alarm
diff --git a/MAINTAINERS b/MAINTAINERS
index caacbcc3b64..c8a0a39d74a 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -3211,6 +3211,13 @@ F:	Documentation/video4linux/*.ivtv
 F:	drivers/media/video/ivtv/
 F:	include/linux/ivtv*
 
+JC42.4 TEMPERATURE SENSOR DRIVER
+M:	Guenter Roeck <linux@roeck-us.net>
+L:	lm-sensors@lm-sensors.org
+S:	Maintained
+F:	drivers/hwmon/jc42.c
+F:	Documentation/hwmon/jc42
+
 JFS FILESYSTEM
 M:	Dave Kleikamp <shaggy@linux.vnet.ibm.com>
 L:	jfs-discussion@lists.sourceforge.net
diff --git a/drivers/hwmon/Kconfig b/drivers/hwmon/Kconfig
index c80ba4943b8..b0de75cf74d 100644
--- a/drivers/hwmon/Kconfig
+++ b/drivers/hwmon/Kconfig
@@ -463,6 +463,17 @@ config SENSORS_JZ4740
 	  This driver can also be build as a module. If so, the module will be
 	  called jz4740-hwmon.
 
+config SENSORS_JC42
+	tristate "JEDEC JC42.4 compliant temperature sensors"
+	help
+	  If you say yes here you get support for Jedec JC42.4 compliant
+	  temperature sensors. Support will include, but not be limited to,
+	  ADT7408, CAT34TS02,, CAT6095, MAX6604, MCP9805, MCP98242, MCP98243,
+	  MCP9843, SE97, SE98, STTS424, TSE2002B3, and TS3000B3.
+
+	  This driver can also be built as a module.  If so, the module
+	  will be called jc42.
+
 config SENSORS_LM63
 	tristate "National Semiconductor LM63 and LM64"
 	depends on I2C
diff --git a/drivers/hwmon/Makefile b/drivers/hwmon/Makefile
index db24fa1aa8b..13d913e34db 100644
--- a/drivers/hwmon/Makefile
+++ b/drivers/hwmon/Makefile
@@ -56,6 +56,7 @@ obj-$(CONFIG_SENSORS_I5K_AMB)	+= i5k_amb.o
 obj-$(CONFIG_SENSORS_IBMAEM)	+= ibmaem.o
 obj-$(CONFIG_SENSORS_IBMPEX)	+= ibmpex.o
 obj-$(CONFIG_SENSORS_IT87)	+= it87.o
+obj-$(CONFIG_SENSORS_JC42)	+= jc42.o
 obj-$(CONFIG_SENSORS_JZ4740)	+= jz4740-hwmon.o
 obj-$(CONFIG_SENSORS_K8TEMP)	+= k8temp.o
 obj-$(CONFIG_SENSORS_K10TEMP)	+= k10temp.o
diff --git a/drivers/hwmon/jc42.c b/drivers/hwmon/jc42.c
new file mode 100644
index 00000000000..340fc78c8dd
--- /dev/null
+++ b/drivers/hwmon/jc42.c
@@ -0,0 +1,593 @@
+/*
+ * jc42.c - driver for Jedec JC42.4 compliant temperature sensors
+ *
+ * Copyright (c) 2010  Ericsson AB.
+ *
+ * Derived from lm77.c by Andras BALI <drewie@freemail.hu>.
+ *
+ * JC42.4 compliant temperature sensors are typically used on memory modules.
+ *
+ * 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.
+ *
+ * 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., 675 Mass Ave, Cambridge, MA 02139, USA.
+ */
+
+#include <linux/module.h>
+#include <linux/init.h>
+#include <linux/slab.h>
+#include <linux/jiffies.h>
+#include <linux/i2c.h>
+#include <linux/hwmon.h>
+#include <linux/hwmon-sysfs.h>
+#include <linux/err.h>
+#include <linux/mutex.h>
+
+/* Addresses to scan */
+static const unsigned short normal_i2c[] = {
+	0x18, 0x19, 0x1a, 0x1b, 0x1c, 0x1d, 0x1e, 0x1f, I2C_CLIENT_END };
+
+/* JC42 registers. All registers are 16 bit. */
+#define JC42_REG_CAP		0x00
+#define JC42_REG_CONFIG		0x01
+#define JC42_REG_TEMP_UPPER	0x02
+#define JC42_REG_TEMP_LOWER	0x03
+#define JC42_REG_TEMP_CRITICAL	0x04
+#define JC42_REG_TEMP		0x05
+#define JC42_REG_MANID		0x06
+#define JC42_REG_DEVICEID	0x07
+
+/* Status bits in temperature register */
+#define JC42_ALARM_CRIT_BIT	15
+#define JC42_ALARM_MAX_BIT	14
+#define JC42_ALARM_MIN_BIT	13
+
+/* Configuration register defines */
+#define JC42_CFG_CRIT_ONLY	(1 << 2)
+#define JC42_CFG_SHUTDOWN	(1 << 8)
+#define JC42_CFG_HYST_SHIFT	9
+#define JC42_CFG_HYST_MASK	0x03
+
+/* Capabilities */
+#define JC42_CAP_RANGE		(1 << 2)
+
+/* Manufacturer IDs */
+#define ADT_MANID		0x11d4  /* Analog Devices */
+#define MAX_MANID		0x004d  /* Maxim */
+#define IDT_MANID		0x00b3  /* IDT */
+#define MCP_MANID		0x0054  /* Microchip */
+#define NXP_MANID		0x1131  /* NXP Semiconductors */
+#define ONS_MANID		0x1b09  /* ON Semiconductor */
+#define STM_MANID		0x104a  /* ST Microelectronics */
+
+/* Supported chips */
+
+/* Analog Devices */
+#define ADT7408_DEVID		0x0801
+#define ADT7408_DEVID_MASK	0xffff
+
+/* IDT */
+#define TS3000B3_DEVID		0x2903  /* Also matches TSE2002B3 */
+#define TS3000B3_DEVID_MASK	0xffff
+
+/* Maxim */
+#define MAX6604_DEVID		0x3e00
+#define MAX6604_DEVID_MASK	0xffff
+
+/* Microchip */
+#define MCP98242_DEVID		0x2000
+#define MCP98242_DEVID_MASK	0xfffc
+
+#define MCP98243_DEVID		0x2100
+#define MCP98243_DEVID_MASK	0xfffc
+
+#define MCP9843_DEVID		0x0000	/* Also matches mcp9805 */
+#define MCP9843_DEVID_MASK	0xfffe
+
+/* NXP */
+#define SE97_DEVID		0xa200
+#define SE97_DEVID_MASK		0xfffc
+
+#define SE98_DEVID		0xa100
+#define SE98_DEVID_MASK		0xfffc
+
+/* ON Semiconductor */
+#define CAT6095_DEVID		0x0800	/* Also matches CAT34TS02 */
+#define CAT6095_DEVID_MASK	0xffe0
+
+/* ST Microelectronics */
+#define STTS424_DEVID		0x0101
+#define STTS424_DEVID_MASK	0xffff
+
+#define STTS424E_DEVID		0x0000
+#define STTS424E_DEVID_MASK	0xfffe
+
+static u16 jc42_hysteresis[] = { 0, 1500, 3000, 6000 };
+
+struct jc42_chips {
+	u16 manid;
+	u16 devid;
+	u16 devid_mask;
+};
+
+static struct jc42_chips jc42_chips[] = {
+	{ ADT_MANID, ADT7408_DEVID, ADT7408_DEVID_MASK },
+	{ IDT_MANID, TS3000B3_DEVID, TS3000B3_DEVID_MASK },
+	{ MAX_MANID, MAX6604_DEVID, MAX6604_DEVID_MASK },
+	{ MCP_MANID, MCP98242_DEVID, MCP98242_DEVID_MASK },
+	{ MCP_MANID, MCP98243_DEVID, MCP98243_DEVID_MASK },
+	{ MCP_MANID, MCP9843_DEVID, MCP9843_DEVID_MASK },
+	{ NXP_MANID, SE97_DEVID, SE97_DEVID_MASK },
+	{ ONS_MANID, CAT6095_DEVID, CAT6095_DEVID_MASK },
+	{ NXP_MANID, SE98_DEVID, SE98_DEVID_MASK },
+	{ STM_MANID, STTS424_DEVID, STTS424_DEVID_MASK },
+	{ STM_MANID, STTS424E_DEVID, STTS424E_DEVID_MASK },
+};
+
+/* Each client has this additional data */
+struct jc42_data {
+	struct device	*hwmon_dev;
+	struct mutex	update_lock;	/* protect register access */
+	bool		extended;	/* true if extended range supported */
+	bool		valid;
+	unsigned long	last_updated;	/* In jiffies */
+	u16		orig_config;	/* original configuration */
+	u16		config;		/* current configuration */
+	u16		temp_input;	/* Temperatures */
+	u16		temp_crit;
+	u16		temp_min;
+	u16		temp_max;
+};
+
+static int jc42_probe(struct i2c_client *client,
+		      const struct i2c_device_id *id);
+static int jc42_detect(struct i2c_client *client, struct i2c_board_info *info);
+static int jc42_remove(struct i2c_client *client);
+static int jc42_read_value(struct i2c_client *client, u8 reg);
+static int jc42_write_value(struct i2c_client *client, u8 reg, u16 value);
+
+static struct jc42_data *jc42_update_device(struct device *dev);
+
+static const struct i2c_device_id jc42_id[] = {
+	{ "adt7408", 0 },
+	{ "cat94ts02", 0 },
+	{ "cat6095", 0 },
+	{ "jc42", 0 },
+	{ "max6604", 0 },
+	{ "mcp9805", 0 },
+	{ "mcp98242", 0 },
+	{ "mcp98243", 0 },
+	{ "mcp9843", 0 },
+	{ "se97", 0 },
+	{ "se97b", 0 },
+	{ "se98", 0 },
+	{ "stts424", 0 },
+	{ "tse2002b3", 0 },
+	{ "ts3000b3", 0 },
+	{ }
+};
+MODULE_DEVICE_TABLE(i2c, jc42_id);
+
+#ifdef CONFIG_PM
+
+static int jc42_suspend(struct device *dev)
+{
+	struct i2c_client *client = to_i2c_client(dev);
+	struct jc42_data *data = i2c_get_clientdata(client);
+
+	data->config |= JC42_CFG_SHUTDOWN;
+	jc42_write_value(client, JC42_REG_CONFIG, data->config);
+	return 0;
+}
+
+static int jc42_resume(struct device *dev)
+{
+	struct i2c_client *client = to_i2c_client(dev);
+	struct jc42_data *data = i2c_get_clientdata(client);
+
+	data->config &= ~JC42_CFG_SHUTDOWN;
+	jc42_write_value(client, JC42_REG_CONFIG, data->config);
+	return 0;
+}
+
+static const struct dev_pm_ops jc42_dev_pm_ops = {
+	.suspend = jc42_suspend,
+	.resume = jc42_resume,
+};
+
+#define JC42_DEV_PM_OPS (&jc42_dev_pm_ops)
+#else
+#define JC42_DEV_PM_OPS NULL
+#endif /* CONFIG_PM */
+
+/* This is the driver that will be inserted */
+static struct i2c_driver jc42_driver = {
+	.class		= I2C_CLASS_HWMON,
+	.driver = {
+		.name	= "jc42",
+		.pm = JC42_DEV_PM_OPS,
+	},
+	.probe		= jc42_probe,
+	.remove		= jc42_remove,
+	.id_table	= jc42_id,
+	.detect		= jc42_detect,
+	.address_list	= normal_i2c,
+};
+
+#define JC42_TEMP_MIN_EXTENDED	(-40000)
+#define JC42_TEMP_MIN		0
+#define JC42_TEMP_MAX		125000
+
+static u16 jc42_temp_to_reg(int temp, bool extended)
+{
+	int ntemp = SENSORS_LIMIT(temp,
+				  extended ? JC42_TEMP_MIN_EXTENDED :
+				  JC42_TEMP_MIN, JC42_TEMP_MAX);
+
+	/* convert from 0.001 to 0.0625 resolution */
+	return (ntemp * 2 / 125) & 0x1fff;
+}
+
+static int jc42_temp_from_reg(s16 reg)
+{
+	reg &= 0x1fff;
+
+	/* sign extend register */
+	if (reg & 0x1000)
+		reg |= 0xf000;
+
+	/* convert from 0.0625 to 0.001 resolution */
+	return reg * 125 / 2;
+}
+
+/* sysfs stuff */
+
+/* read routines for temperature limits */
+#define show(value)	\
+static ssize_t show_##value(struct device *dev,				\
+			    struct device_attribute *attr,		\
+			    char *buf)					\
+{									\
+	struct jc42_data *data = jc42_update_device(dev);		\
+	if (IS_ERR(data))						\
+		return PTR_ERR(data);					\
+	return sprintf(buf, "%d\n", jc42_temp_from_reg(data->value));	\
+}
+
+show(temp_input);
+show(temp_crit);
+show(temp_min);
+show(temp_max);
+
+/* read routines for hysteresis values */
+static ssize_t show_temp_crit_hyst(struct device *dev,
+				   struct device_attribute *attr, char *buf)
+{
+	struct jc42_data *data = jc42_update_device(dev);
+	int temp, hyst;
+
+	if (IS_ERR(data))
+		return PTR_ERR(data);
+
+	temp = jc42_temp_from_reg(data->temp_crit);
+	hyst = jc42_hysteresis[(data->config >> JC42_CFG_HYST_SHIFT)
+			       & JC42_CFG_HYST_MASK];
+	return sprintf(buf, "%d\n", temp - hyst);
+}
+
+static ssize_t show_temp_max_hyst(struct device *dev,
+				  struct device_attribute *attr, char *buf)
+{
+	struct jc42_data *data = jc42_update_device(dev);
+	int temp, hyst;
+
+	if (IS_ERR(data))
+		return PTR_ERR(data);
+
+	temp = jc42_temp_from_reg(data->temp_max);
+	hyst = jc42_hysteresis[(data->config >> JC42_CFG_HYST_SHIFT)
+			       & JC42_CFG_HYST_MASK];
+	return sprintf(buf, "%d\n", temp - hyst);
+}
+
+/* write routines */
+#define set(value, reg)	\
+static ssize_t set_##value(struct device *dev,				\
+			   struct device_attribute *attr,		\
+			   const char *buf, size_t count)		\
+{									\
+	struct i2c_client *client = to_i2c_client(dev);			\
+	struct jc42_data *data = i2c_get_clientdata(client);		\
+	int err, ret = count;						\
+	long val;							\
+	if (strict_strtol(buf, 10, &val) < 0)				\
+		return -EINVAL;						\
+	mutex_lock(&data->update_lock);					\
+	data->value = jc42_temp_to_reg(val, data->extended);		\
+	err = jc42_write_value(client, reg, data->value);		\
+	if (err < 0)							\
+		ret = err;						\
+	mutex_unlock(&data->update_lock);				\
+	return ret;							\
+}
+
+set(temp_min, JC42_REG_TEMP_LOWER);
+set(temp_max, JC42_REG_TEMP_UPPER);
+set(temp_crit, JC42_REG_TEMP_CRITICAL);
+
+/* JC42.4 compliant chips only support four hysteresis values.
+ * Pick best choice and go from there. */
+static ssize_t set_temp_crit_hyst(struct device *dev,
+				  struct device_attribute *attr,
+				  const char *buf, size_t count)
+{
+	struct i2c_client *client = to_i2c_client(dev);
+	struct jc42_data *data = i2c_get_clientdata(client);
+	long val;
+	int diff, hyst;
+	int err;
+	int ret = count;
+
+	if (strict_strtoul(buf, 10, &val) < 0)
+		return -EINVAL;
+
+	diff = jc42_temp_from_reg(data->temp_crit) - val;
+	hyst = 0;
+	if (diff > 0) {
+		if (diff < 2250)
+			hyst = 1;	/* 1.5 degrees C */
+		else if (diff < 4500)
+			hyst = 2;	/* 3.0 degrees C */
+		else
+			hyst = 3;	/* 6.0 degrees C */
+	}
+
+	mutex_lock(&data->update_lock);
+	data->config = (data->config
+			& ~(JC42_CFG_HYST_MASK << JC42_CFG_HYST_SHIFT))
+	  | (hyst << JC42_CFG_HYST_SHIFT);
+	err = jc42_write_value(client, JC42_REG_CONFIG, data->config);
+	if (err < 0)
+		ret = err;
+	mutex_unlock(&data->update_lock);
+	return ret;
+}
+
+static ssize_t show_alarm(struct device *dev,
+			  struct device_attribute *attr, char *buf)
+{
+	u16 bit = to_sensor_dev_attr(attr)->index;
+	struct jc42_data *data = jc42_update_device(dev);
+	u16 val;
+
+	if (IS_ERR(data))
+		return PTR_ERR(data);
+
+	val = data->temp_input;
+	if (bit != JC42_ALARM_CRIT_BIT && (data->config & JC42_CFG_CRIT_ONLY))
+		val = 0;
+	return sprintf(buf, "%u\n", (val >> bit) & 1);
+}
+
+static DEVICE_ATTR(temp1_input, S_IRUGO,
+		   show_temp_input, NULL);
+static DEVICE_ATTR(temp1_crit, S_IWUSR | S_IRUGO,
+		   show_temp_crit, set_temp_crit);
+static DEVICE_ATTR(temp1_min, S_IWUSR | S_IRUGO,
+		   show_temp_min, set_temp_min);
+static DEVICE_ATTR(temp1_max, S_IWUSR | S_IRUGO,
+		   show_temp_max, set_temp_max);
+
+static DEVICE_ATTR(temp1_crit_hyst, S_IWUSR | S_IRUGO,
+		   show_temp_crit_hyst, set_temp_crit_hyst);
+static DEVICE_ATTR(temp1_max_hyst, S_IRUGO,
+		   show_temp_max_hyst, NULL);
+
+static SENSOR_DEVICE_ATTR(temp1_crit_alarm, S_IRUGO, show_alarm, NULL,
+			  JC42_ALARM_CRIT_BIT);
+static SENSOR_DEVICE_ATTR(temp1_min_alarm, S_IRUGO, show_alarm, NULL,
+			  JC42_ALARM_MIN_BIT);
+static SENSOR_DEVICE_ATTR(temp1_max_alarm, S_IRUGO, show_alarm, NULL,
+			  JC42_ALARM_MAX_BIT);
+
+static struct attribute *jc42_attributes[] = {
+	&dev_attr_temp1_input.attr,
+	&dev_attr_temp1_crit.attr,
+	&dev_attr_temp1_min.attr,
+	&dev_attr_temp1_max.attr,
+	&dev_attr_temp1_crit_hyst.attr,
+	&dev_attr_temp1_max_hyst.attr,
+	&sensor_dev_attr_temp1_crit_alarm.dev_attr.attr,
+	&sensor_dev_attr_temp1_min_alarm.dev_attr.attr,
+	&sensor_dev_attr_temp1_max_alarm.dev_attr.attr,
+	NULL
+};
+
+static const struct attribute_group jc42_group = {
+	.attrs = jc42_attributes,
+};
+
+/* Return 0 if detection is successful, -ENODEV otherwise */
+static int jc42_detect(struct i2c_client *new_client,
+		       struct i2c_board_info *info)
+{
+	struct i2c_adapter *adapter = new_client->adapter;
+	int i, config, cap, manid, devid;
+
+	if (!i2c_check_functionality(adapter, I2C_FUNC_SMBUS_BYTE_DATA |
+				     I2C_FUNC_SMBUS_WORD_DATA))
+		return -ENODEV;
+
+	cap = jc42_read_value(new_client, JC42_REG_CAP);
+	config = jc42_read_value(new_client, JC42_REG_CONFIG);
+	manid = jc42_read_value(new_client, JC42_REG_MANID);
+	devid = jc42_read_value(new_client, JC42_REG_DEVICEID);
+
+	if (cap < 0 || config < 0 || manid < 0 || devid < 0)
+		return -ENODEV;
+
+	if ((cap & 0xff00) || (config & 0xf800))
+		return -ENODEV;
+
+	for (i = 0; i < ARRAY_SIZE(jc42_chips); i++) {
+		struct jc42_chips *chip = &jc42_chips[i];
+		if (manid == chip->manid &&
+		    (devid & chip->devid_mask) == chip->devid) {
+			strlcpy(info->type, "jc42", I2C_NAME_SIZE);
+			return 0;
+		}
+	}
+	return -ENODEV;
+}
+
+static int jc42_probe(struct i2c_client *new_client,
+		      const struct i2c_device_id *id)
+{
+	struct jc42_data *data;
+	int config, cap, err;
+
+	data = kzalloc(sizeof(struct jc42_data), GFP_KERNEL);
+	if (!data) {
+		err = -ENOMEM;
+		goto exit;
+	}
+
+	i2c_set_clientdata(new_client, data);
+	mutex_init(&data->update_lock);
+
+	cap = jc42_read_value(new_client, JC42_REG_CAP);
+	if (cap < 0) {
+		err = -EINVAL;
+		goto exit_free;
+	}
+	data->extended = !!(cap & JC42_CAP_RANGE);
+
+	config = jc42_read_value(new_client, JC42_REG_CONFIG);
+	if (config < 0) {
+		err = -EINVAL;
+		goto exit_free;
+	}
+	data->orig_config = config;
+	if (config & JC42_CFG_SHUTDOWN) {
+		config &= ~JC42_CFG_SHUTDOWN;
+		jc42_write_value(new_client, JC42_REG_CONFIG, config);
+	}
+	data->config = config;
+
+	/* Register sysfs hooks */
+	err = sysfs_create_group(&new_client->dev.kobj, &jc42_group);
+	if (err)
+		goto exit_free;
+
+	data->hwmon_dev = hwmon_device_register(&new_client->dev);
+	if (IS_ERR(data->hwmon_dev)) {
+		err = PTR_ERR(data->hwmon_dev);
+		goto exit_remove;
+	}
+
+	return 0;
+
+exit_remove:
+	sysfs_remove_group(&new_client->dev.kobj, &jc42_group);
+exit_free:
+	kfree(data);
+exit:
+	return err;
+}
+
+static int jc42_remove(struct i2c_client *client)
+{
+	struct jc42_data *data = i2c_get_clientdata(client);
+	hwmon_device_unregister(data->hwmon_dev);
+	sysfs_remove_group(&client->dev.kobj, &jc42_group);
+	if (data->config != data->orig_config)
+		jc42_write_value(client, JC42_REG_CONFIG, data->orig_config);
+	kfree(data);
+	return 0;
+}
+
+/* All registers are word-sized. */
+static int jc42_read_value(struct i2c_client *client, u8 reg)
+{
+	int ret = i2c_smbus_read_word_data(client, reg);
+	if (ret < 0)
+		return ret;
+	return swab16(ret);
+}
+
+static int jc42_write_value(struct i2c_client *client, u8 reg, u16 value)
+{
+	return i2c_smbus_write_word_data(client, reg, swab16(value));
+}
+
+static struct jc42_data *jc42_update_device(struct device *dev)
+{
+	struct i2c_client *client = to_i2c_client(dev);
+	struct jc42_data *data = i2c_get_clientdata(client);
+	struct jc42_data *ret = data;
+	int val;
+
+	mutex_lock(&data->update_lock);
+
+	if (time_after(jiffies, data->last_updated + HZ) || !data->valid) {
+		val = jc42_read_value(client, JC42_REG_TEMP);
+		if (val < 0) {
+			ret = ERR_PTR(val);
+			goto abort;
+		}
+		data->temp_input = val;
+
+		val = jc42_read_value(client, JC42_REG_TEMP_CRITICAL);
+		if (val < 0) {
+			ret = ERR_PTR(val);
+			goto abort;
+		}
+		data->temp_crit = val;
+
+		val = jc42_read_value(client, JC42_REG_TEMP_LOWER);
+		if (val < 0) {
+			ret = ERR_PTR(val);
+			goto abort;
+		}
+		data->temp_min = val;
+
+		val = jc42_read_value(client, JC42_REG_TEMP_UPPER);
+		if (val < 0) {
+			ret = ERR_PTR(val);
+			goto abort;
+		}
+		data->temp_max = val;
+
+		data->last_updated = jiffies;
+		data->valid = true;
+	}
+abort:
+	mutex_unlock(&data->update_lock);
+	return ret;
+}
+
+static int __init sensors_jc42_init(void)
+{
+	return i2c_add_driver(&jc42_driver);
+}
+
+static void __exit sensors_jc42_exit(void)
+{
+	i2c_del_driver(&jc42_driver);
+}
+
+MODULE_AUTHOR("Guenter Roeck <guenter.roeck@ericsson.com>");
+MODULE_DESCRIPTION("JC42 driver");
+MODULE_LICENSE("GPL");
+
+module_init(sensors_jc42_init);
+module_exit(sensors_jc42_exit);