diff --git a/drivers/hwmon/tmp421.c b/drivers/hwmon/tmp421.c
new file mode 100644
index 0000000..e363992
--- /dev/null
+++ b/drivers/hwmon/tmp421.c
@@ -0,0 +1,346 @@
+/* tmp421.c
+ *
+ * Copyright (C) 2009 Andre Prendel <andre.prendel@gmx.de>
+ * Preliminary support by:
+ * Melvin Rook, Raymond Ng
+ *
+ * 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.
+ */
+
+/*
+ * Driver for the Texas Instruments TMP421 SMBus temperature sensor IC.
+ * Supported models: TMP421, TMP422, TMP423, TMP441, TMP442
+ */
+
+#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>
+#include <linux/of_device.h>
+#include <linux/sysfs.h>
+
+/* Addresses to scan */
+static const unsigned short normal_i2c[] = { 0x2a, 0x4c, 0x4d, 0x4e, 0x4f,
+					     I2C_CLIENT_END };
+
+enum chips { tmp421, tmp422, tmp423, tmp441, tmp442 };
+
+/* The TMP421 registers */
+#define TMP421_STATUS_REG			0x08
+#define TMP421_CONFIG_REG_1			0x09
+#define TMP421_CONVERSION_RATE_REG		0x0B
+#define TMP421_MANUFACTURER_ID_REG		0xFE
+#define TMP421_DEVICE_ID_REG			0xFF
+
+static const u8 TMP421_TEMP_MSB[4]		= { 0x00, 0x01, 0x02, 0x03 };
+static const u8 TMP421_TEMP_LSB[4]		= { 0x10, 0x11, 0x12, 0x13 };
+
+/* Flags */
+#define TMP421_CONFIG_SHUTDOWN			0x40
+#define TMP421_CONFIG_RANGE			0x04
+
+/* Manufacturer / Device ID's */
+#define TMP421_MANUFACTURER_ID			0x55
+#define TMP421_DEVICE_ID			0x21
+#define TMP422_DEVICE_ID			0x22
+#define TMP423_DEVICE_ID			0x23
+#define TMP441_DEVICE_ID			0x41
+#define TMP442_DEVICE_ID			0x42
+
+static const struct i2c_device_id tmp421_id[] = {
+	{ "tmp421", 2 },
+	{ "tmp422", 3 },
+	{ "tmp423", 4 },
+	{ "tmp441", 2 },
+	{ "tmp442", 3 },
+	{ }
+};
+MODULE_DEVICE_TABLE(i2c, tmp421_id);
+
+static const struct of_device_id tmp421_of_match[] = {
+	{
+		.compatible = "ti,tmp421",
+		.data = (void *)2
+	},
+	{
+		.compatible = "ti,tmp422",
+		.data = (void *)3
+	},
+	{
+		.compatible = "ti,tmp423",
+		.data = (void *)4
+	},
+	{
+		.compatible = "ti,tmp441",
+		.data = (void *)2
+	},
+	{
+		.compatible = "ti,tmp422",
+		.data = (void *)3
+	},
+	{ },
+};
+MODULE_DEVICE_TABLE(of, tmp421_of_match);
+
+struct tmp421_data {
+	struct i2c_client *client;
+	struct mutex update_lock;
+	u32 temp_config[5];
+	struct hwmon_channel_info temp_info;
+	const struct hwmon_channel_info *info[2];
+	struct hwmon_chip_info chip;
+	char valid;
+	unsigned long last_updated;
+	unsigned long channels;
+	u8 config;
+	s16 temp[4];
+};
+
+static int temp_from_s16(s16 reg)
+{
+	/* Mask out status bits */
+	int temp = reg & ~0xf;
+
+	return (temp * 1000 + 128) / 256;
+}
+
+static int temp_from_u16(u16 reg)
+{
+	/* Mask out status bits */
+	int temp = reg & ~0xf;
+
+	/* Add offset for extended temperature range. */
+	temp -= 64 * 256;
+
+	return (temp * 1000 + 128) / 256;
+}
+
+static struct tmp421_data *tmp421_update_device(struct device *dev)
+{
+	struct tmp421_data *data = dev_get_drvdata(dev);
+	struct i2c_client *client = data->client;
+	int i;
+
+	mutex_lock(&data->update_lock);
+
+	if (time_after(jiffies, data->last_updated + 2 * HZ) || !data->valid) {
+		data->config = i2c_smbus_read_byte_data(client,
+			TMP421_CONFIG_REG_1);
+
+		for (i = 0; i < data->channels; i++) {
+			data->temp[i] = i2c_smbus_read_byte_data(client,
+				TMP421_TEMP_MSB[i]) << 8;
+			data->temp[i] |= i2c_smbus_read_byte_data(client,
+				TMP421_TEMP_LSB[i]);
+		}
+		data->last_updated = jiffies;
+		data->valid = 1;
+	}
+
+	mutex_unlock(&data->update_lock);
+
+	return data;
+}
+
+static int tmp421_read(struct device *dev, enum hwmon_sensor_types type,
+		       u32 attr, int channel, long *val)
+{
+	struct tmp421_data *tmp421 = tmp421_update_device(dev);
+
+	switch (attr) {
+	case hwmon_temp_input:
+		if (tmp421->config & TMP421_CONFIG_RANGE)
+			*val = temp_from_u16(tmp421->temp[channel]);
+		else
+			*val = temp_from_s16(tmp421->temp[channel]);
+		return 0;
+	case hwmon_temp_fault:
+		/*
+		 * The OPEN bit signals a fault. This is bit 0 of the temperature
+		 * register (low byte).
+		 */
+		*val = tmp421->temp[channel] & 0x01;
+		return 0;
+	default:
+		return -EOPNOTSUPP;
+	}
+
+}
+
+static umode_t tmp421_is_visible(const void *data, enum hwmon_sensor_types type,
+				 u32 attr, int channel)
+{
+	switch (attr) {
+	case hwmon_temp_fault:
+		if (channel == 0)
+			return 0;
+		return S_IRUGO;
+	case hwmon_temp_input:
+		return S_IRUGO;
+	default:
+		return 0;
+	}
+}
+
+static int tmp421_init_client(struct i2c_client *client)
+{
+	int config, config_orig;
+
+	/* Set the conversion rate to 2 Hz */
+	i2c_smbus_write_byte_data(client, TMP421_CONVERSION_RATE_REG, 0x05);
+
+	/* Start conversions (disable shutdown if necessary) */
+	config = i2c_smbus_read_byte_data(client, TMP421_CONFIG_REG_1);
+	if (config < 0) {
+		dev_err(&client->dev,
+			"Could not read configuration register (%d)\n", config);
+		return config;
+	}
+
+	config_orig = config;
+	config &= ~TMP421_CONFIG_SHUTDOWN;
+
+	if (config != config_orig) {
+		dev_info(&client->dev, "Enable monitoring chip\n");
+		i2c_smbus_write_byte_data(client, TMP421_CONFIG_REG_1, config);
+	}
+
+	return 0;
+}
+
+static int tmp421_detect(struct i2c_client *client,
+			 struct i2c_board_info *info)
+{
+	enum chips kind;
+	struct i2c_adapter *adapter = client->adapter;
+	const char * const names[] = { "TMP421", "TMP422", "TMP423",
+				       "TMP441", "TMP442" };
+	int addr = client->addr;
+	u8 reg;
+
+	if (!i2c_check_functionality(adapter, I2C_FUNC_SMBUS_BYTE_DATA))
+		return -ENODEV;
+
+	reg = i2c_smbus_read_byte_data(client, TMP421_MANUFACTURER_ID_REG);
+	if (reg != TMP421_MANUFACTURER_ID)
+		return -ENODEV;
+
+	reg = i2c_smbus_read_byte_data(client, TMP421_CONVERSION_RATE_REG);
+	if (reg & 0xf8)
+		return -ENODEV;
+
+	reg = i2c_smbus_read_byte_data(client, TMP421_STATUS_REG);
+	if (reg & 0x7f)
+		return -ENODEV;
+
+	reg = i2c_smbus_read_byte_data(client, TMP421_DEVICE_ID_REG);
+	switch (reg) {
+	case TMP421_DEVICE_ID:
+		kind = tmp421;
+		break;
+	case TMP422_DEVICE_ID:
+		if (addr == 0x2a)
+			return -ENODEV;
+		kind = tmp422;
+		break;
+	case TMP423_DEVICE_ID:
+		if (addr != 0x4c && addr != 0x4d)
+			return -ENODEV;
+		kind = tmp423;
+		break;
+	case TMP441_DEVICE_ID:
+		kind = tmp441;
+		break;
+	case TMP442_DEVICE_ID:
+		if (addr != 0x4c && addr != 0x4d)
+			return -ENODEV;
+		kind = tmp442;
+		break;
+	default:
+		return -ENODEV;
+	}
+
+	strlcpy(info->type, tmp421_id[kind].name, I2C_NAME_SIZE);
+	dev_info(&adapter->dev, "Detected TI %s chip at 0x%02x\n",
+		 names[kind], client->addr);
+
+	return 0;
+}
+
+static const struct hwmon_ops tmp421_ops = {
+	.is_visible = tmp421_is_visible,
+	.read = tmp421_read,
+};
+
+static int tmp421_probe(struct i2c_client *client,
+			const struct i2c_device_id *id)
+{
+	struct device *dev = &client->dev;
+	struct device *hwmon_dev;
+	struct tmp421_data *data;
+	int i, err;
+
+	data = devm_kzalloc(dev, sizeof(struct tmp421_data), GFP_KERNEL);
+	if (!data)
+		return -ENOMEM;
+
+	mutex_init(&data->update_lock);
+	if (client->dev.of_node)
+		data->channels = (unsigned long)
+			of_device_get_match_data(&client->dev);
+	else
+		data->channels = id->driver_data;
+	data->client = client;
+
+	err = tmp421_init_client(client);
+	if (err)
+		return err;
+
+	for (i = 0; i < data->channels; i++)
+		data->temp_config[i] = HWMON_T_INPUT | HWMON_T_FAULT;
+
+	data->chip.ops = &tmp421_ops;
+	data->chip.info = data->info;
+
+	data->info[0] = &data->temp_info;
+
+	data->temp_info.type = hwmon_temp;
+	data->temp_info.config = data->temp_config;
+
+	hwmon_dev = devm_hwmon_device_register_with_info(dev, client->name,
+							 data,
+							 &data->chip,
+							 NULL);
+	return PTR_ERR_OR_ZERO(hwmon_dev);
+}
+
+static struct i2c_driver tmp421_driver = {
+	.class = I2C_CLASS_HWMON,
+	.driver = {
+		.name	= "tmp421",
+		.of_match_table = of_match_ptr(tmp421_of_match),
+	},
+	.probe = tmp421_probe,
+	.id_table = tmp421_id,
+	.detect = tmp421_detect,
+	.address_list = normal_i2c,
+};
+
+module_i2c_driver(tmp421_driver);
+
+MODULE_AUTHOR("Andre Prendel <andre.prendel@gmx.de>");
+MODULE_DESCRIPTION("Texas Instruments TMP421/422/423/441/442 temperature sensor driver");
+MODULE_LICENSE("GPL");