x86/kprobes: Fix crash when probing CS CALL instructionsgrafted

When using eBPF to probe CS CALL instructions within a function,
a crash can be triggered.

The eBPF tool probes offset 257 of the __hrtimer_run_queues()
function:

<__hrtimer_run_queues+249>:  nopl   0x0(%rax,%rax,1)
<__hrtimer_run_queues+254>:  mov    %r14,%rdi
<__hrtimer_run_queues+257>:  cs call <__x86_indirect_thunk_r12>
<__hrtimer_run_queues+263>:  mov    %eax,%r12d
<__hrtimer_run_queues+266>:  xchg   %ax,%ax
<__hrtimer_run_queues+268>:  mov    %r13,%rdi

Which triggers this crash:

  BUG: unable to handle page fault for address: 00000000000f41c9
  #PF: supervisor write access in kernel mode
  #PF: error_code(0x0002) - not-present page
  PGD 0 P4D 0
  Oops: 0002 [#1] SMP NOPTI
  CPU: 1 PID: 0 Comm: swapper/1 Kdump: loaded Tainted: P
  RIP: 0010:__hrtimer_run_queues+0x106/0x230

Note that __hrtimer_run_queues+0x106 is __hrtimer_run_queues+262, which is
at the 6th byte of the above CS CALL instruction. Since the CS CALL
instruction occupies 6 bytes, the exception occurred in the middle of that
call instruction.

The root cause is that when using eBPF tools to probe in the middle of a
function, a kprobe with INT3 is used as the underlying implementation.

During single-step emulation of the original CALL instruction,
int3_emulate_call() assumes that the probed CALL instruction is 5 bytes
long. However, the actual CS-prefixed CALL instruction occupies 6 bytes,
so it constructs an incorrect exception return address. When the CPU
returns from the kprobe handler, the next instruction to be executed is at
the address of the last byte of that CS CALL instruction. Coincidentally,
starting from that address, the CPU fetches and decodes a completely
different instruction, which ultimately triggers a kernel crash.

Fix the issue by using the actual instruction length obtained from
the instruction decoder when constructing the exception return
address, rather than relying on the hardcoded CALL_INSN_SIZE macro.

[ mingo: Refined the changelog ]

Fixes: 6256e668b7af ("x86/kprobes: Use int3 instead of debug trap for single-step")
Suggested-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>
Signed-off-by: Jinke Han <jinkehan@didiglobal.com>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Reviewed-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>
Acked-by: Yafang Shao <laoar.shao@gmail.com>
Acked-by: Borislav Petkov <bp@alien8.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Link: https://patch.msgid.link/20260908073742.GA10517@didi-ThinkCentre-M920t-N000

1 files changed, 659 insertions, 0 deletions

diff --git a/drivers/hwmon/ftsteutates.c b/drivers/hwmon/ftsteutates.c
new file mode 100644
index 000000000..06be120a3
--- /dev/null
+++ b/drivers/hwmon/ftsteutates.c
@@ -0,0 +1,659 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * Support for the FTS Systemmonitoring Chip "Teutates"
+ *
+ * Copyright (C) 2016 Fujitsu Technology Solutions GmbH,
+ *		  Thilo Cestonaro <thilo.cestonaro@ts.fujitsu.com>
+ */
+#include <linux/err.h>
+#include <linux/hwmon.h>
+#include <linux/i2c.h>
+#include <linux/init.h>
+#include <linux/jiffies.h>
+#include <linux/math.h>
+#include <linux/module.h>
+#include <linux/slab.h>
+#include <linux/watchdog.h>
+
+#define FTS_DEVICE_ID_REG		0x0000
+#define FTS_DEVICE_REVISION_REG		0x0001
+#define FTS_DEVICE_STATUS_REG		0x0004
+#define FTS_SATELLITE_STATUS_REG	0x0005
+#define FTS_EVENT_STATUS_REG		0x0006
+#define FTS_GLOBAL_CONTROL_REG		0x0007
+
+#define FTS_DEVICE_DETECT_REG_1		0x0C
+#define FTS_DEVICE_DETECT_REG_2		0x0D
+#define FTS_DEVICE_DETECT_REG_3		0x0E
+
+#define FTS_SENSOR_EVENT_REG		0x0010
+
+#define FTS_FAN_EVENT_REG		0x0014
+#define FTS_FAN_PRESENT_REG		0x0015
+
+#define FTS_POWER_ON_TIME_COUNTER_A	0x007A
+#define FTS_POWER_ON_TIME_COUNTER_B	0x007B
+#define FTS_POWER_ON_TIME_COUNTER_C	0x007C
+
+#define FTS_PAGE_SELECT_REG		0x007F
+
+#define FTS_WATCHDOG_TIME_PRESET	0x000B
+#define FTS_WATCHDOG_CONTROL		0x5081
+
+#define FTS_NO_FAN_SENSORS		0x08
+#define FTS_NO_TEMP_SENSORS		0x10
+#define FTS_NO_VOLT_SENSORS		0x04
+
+#define FTS_FAN_SOURCE_INVALID		0xff
+
+static const unsigned short normal_i2c[] = { 0x73, I2C_CLIENT_END };
+
+static const struct i2c_device_id fts_id[] = {
+	{ .name = "ftsteutates" },
+	{ }
+};
+MODULE_DEVICE_TABLE(i2c, fts_id);
+
+enum WATCHDOG_RESOLUTION {
+	seconds = 1,
+	minutes = 60
+};
+
+struct fts_data {
+	struct i2c_client *client;
+	unsigned long last_updated; /* in jiffies */
+	struct watchdog_device wdd;
+	enum WATCHDOG_RESOLUTION resolution;
+	bool valid; /* false until following fields are valid */
+
+	u8 volt[FTS_NO_VOLT_SENSORS];
+
+	u8 temp_input[FTS_NO_TEMP_SENSORS];
+	u8 temp_alarm;
+
+	u8 fan_present;
+	u8 fan_input[FTS_NO_FAN_SENSORS]; /* in rps */
+	u8 fan_source[FTS_NO_FAN_SENSORS];
+	u8 fan_alarm;
+};
+
+#define FTS_REG_FAN_INPUT(idx) ((idx) + 0x20)
+#define FTS_REG_FAN_SOURCE(idx) ((idx) + 0x30)
+#define FTS_REG_FAN_CONTROL(idx) (((idx) << 16) + 0x4881)
+
+#define FTS_REG_TEMP_INPUT(idx) ((idx) + 0x40)
+#define FTS_REG_TEMP_CONTROL(idx) (((idx) << 16) + 0x0681)
+
+#define FTS_REG_VOLT(idx) ((idx) + 0x18)
+
+/*****************************************************************************/
+/* I2C Helper functions							     */
+/*****************************************************************************/
+static int fts_read_byte(struct i2c_client *client, unsigned short reg)
+{
+	int ret;
+	unsigned char page = reg >> 8;
+
+	dev_dbg(&client->dev, "page select - page: 0x%.02x\n", page);
+	ret = i2c_smbus_write_byte_data(client, FTS_PAGE_SELECT_REG, page);
+	if (ret < 0)
+		return ret;
+
+	reg &= 0xFF;
+	ret = i2c_smbus_read_byte_data(client, reg);
+	dev_dbg(&client->dev, "read - reg: 0x%.02x: val: 0x%.02x\n", reg, ret);
+	return ret;
+}
+
+static int fts_write_byte(struct i2c_client *client, unsigned short reg,
+			  unsigned char value)
+{
+	int ret;
+	unsigned char page = reg >> 8;
+
+	dev_dbg(&client->dev, "page select - page: 0x%.02x\n", page);
+	ret = i2c_smbus_write_byte_data(client, FTS_PAGE_SELECT_REG, page);
+	if (ret < 0)
+		return ret;
+
+	reg &= 0xFF;
+	dev_dbg(&client->dev,
+		"write - reg: 0x%.02x: val: 0x%.02x\n", reg, value);
+	ret = i2c_smbus_write_byte_data(client, reg, value);
+	return ret;
+}
+
+/*****************************************************************************/
+/* Data Updater Helper function						     */
+/*****************************************************************************/
+static int fts_update_device(struct fts_data *data)
+{
+	int i, err;
+
+	if (!time_after(jiffies, data->last_updated + 2 * HZ) && data->valid)
+		return 0;
+
+	err = fts_read_byte(data->client, FTS_DEVICE_STATUS_REG);
+	if (err < 0)
+		return err;
+
+	data->valid = !!(err & 0x02); /* Data not ready yet */
+	if (unlikely(!data->valid))
+		return -EAGAIN;
+
+	err = fts_read_byte(data->client, FTS_FAN_PRESENT_REG);
+	if (err < 0)
+		return err;
+	data->fan_present = err;
+
+	err = fts_read_byte(data->client, FTS_FAN_EVENT_REG);
+	if (err < 0)
+		return err;
+	data->fan_alarm = err;
+
+	for (i = 0; i < FTS_NO_FAN_SENSORS; i++) {
+		if (data->fan_present & BIT(i)) {
+			err = fts_read_byte(data->client, FTS_REG_FAN_INPUT(i));
+			if (err < 0)
+				return err;
+			data->fan_input[i] = err;
+
+			err = fts_read_byte(data->client,
+					    FTS_REG_FAN_SOURCE(i));
+			if (err < 0)
+				return err;
+			data->fan_source[i] = err;
+		} else {
+			data->fan_input[i] = 0;
+			data->fan_source[i] = FTS_FAN_SOURCE_INVALID;
+		}
+	}
+
+	err = fts_read_byte(data->client, FTS_SENSOR_EVENT_REG);
+	if (err < 0)
+		return err;
+	data->temp_alarm = err;
+
+	for (i = 0; i < FTS_NO_TEMP_SENSORS; i++) {
+		err = fts_read_byte(data->client, FTS_REG_TEMP_INPUT(i));
+		if (err < 0)
+			return err;
+		data->temp_input[i] = err;
+	}
+
+	for (i = 0; i < FTS_NO_VOLT_SENSORS; i++) {
+		err = fts_read_byte(data->client, FTS_REG_VOLT(i));
+		if (err < 0)
+			return err;
+		data->volt[i] = err;
+	}
+	data->last_updated = jiffies;
+	return 0;
+}
+
+/*****************************************************************************/
+/* Watchdog functions							     */
+/*****************************************************************************/
+static int fts_wd_set_resolution(struct fts_data *data,
+				 enum WATCHDOG_RESOLUTION resolution)
+{
+	int ret;
+
+	if (data->resolution == resolution)
+		return 0;
+
+	ret = fts_read_byte(data->client, FTS_WATCHDOG_CONTROL);
+	if (ret < 0)
+		return ret;
+
+	if ((resolution == seconds && ret & BIT(1)) ||
+	    (resolution == minutes && (ret & BIT(1)) == 0)) {
+		data->resolution = resolution;
+		return 0;
+	}
+
+	if (resolution == seconds)
+		ret |= BIT(1);
+	else
+		ret &= ~BIT(1);
+
+	ret = fts_write_byte(data->client, FTS_WATCHDOG_CONTROL, ret);
+	if (ret < 0)
+		return ret;
+
+	data->resolution = resolution;
+	return ret;
+}
+
+static int fts_wd_set_timeout(struct watchdog_device *wdd, unsigned int timeout)
+{
+	struct fts_data *data;
+	enum WATCHDOG_RESOLUTION resolution = seconds;
+	int ret;
+
+	data = watchdog_get_drvdata(wdd);
+	/* switch watchdog resolution to minutes if timeout does not fit
+	 * into a byte
+	 */
+	if (timeout > 0xFF) {
+		timeout = DIV_ROUND_UP(timeout, 60) * 60;
+		resolution = minutes;
+	}
+
+	ret = fts_wd_set_resolution(data, resolution);
+	if (ret < 0)
+		return ret;
+
+	wdd->timeout = timeout;
+	return 0;
+}
+
+static int fts_wd_start(struct watchdog_device *wdd)
+{
+	struct fts_data *data = watchdog_get_drvdata(wdd);
+
+	return fts_write_byte(data->client, FTS_WATCHDOG_TIME_PRESET,
+			      wdd->timeout / (u8)data->resolution);
+}
+
+static int fts_wd_stop(struct watchdog_device *wdd)
+{
+	struct fts_data *data;
+
+	data = watchdog_get_drvdata(wdd);
+	return fts_write_byte(data->client, FTS_WATCHDOG_TIME_PRESET, 0);
+}
+
+static const struct watchdog_info fts_wd_info = {
+	.options = WDIOF_SETTIMEOUT | WDIOF_KEEPALIVEPING | WDIOF_MAGICCLOSE,
+	.identity = "FTS Teutates Hardware Watchdog",
+};
+
+static const struct watchdog_ops fts_wd_ops = {
+	.owner = THIS_MODULE,
+	.start = fts_wd_start,
+	.stop = fts_wd_stop,
+	.set_timeout = fts_wd_set_timeout,
+};
+
+static int fts_watchdog_init(struct fts_data *data)
+{
+	int timeout, ret;
+
+	watchdog_set_drvdata(&data->wdd, data);
+
+	timeout = fts_read_byte(data->client, FTS_WATCHDOG_TIME_PRESET);
+	if (timeout < 0)
+		return timeout;
+
+	/* watchdog not running, set timeout to a default of 60 sec. */
+	if (timeout == 0) {
+		ret = fts_wd_set_resolution(data, seconds);
+		if (ret < 0)
+			return ret;
+		data->wdd.timeout = 60;
+	} else {
+		ret = fts_read_byte(data->client, FTS_WATCHDOG_CONTROL);
+		if (ret < 0)
+			return ret;
+
+		data->resolution = ret & BIT(1) ? seconds : minutes;
+		data->wdd.timeout = timeout * (u8)data->resolution;
+		set_bit(WDOG_HW_RUNNING, &data->wdd.status);
+	}
+
+	/* Register our watchdog part */
+	data->wdd.info = &fts_wd_info;
+	data->wdd.ops = &fts_wd_ops;
+	data->wdd.parent = &data->client->dev;
+	data->wdd.min_timeout = 1;
+
+	/* max timeout 255 minutes. */
+	data->wdd.max_hw_heartbeat_ms = 0xFF * 60 * MSEC_PER_SEC;
+
+	return devm_watchdog_register_device(&data->client->dev, &data->wdd);
+}
+
+static umode_t fts_is_visible(const void *devdata, enum hwmon_sensor_types type, u32 attr,
+			      int channel)
+{
+	switch (type) {
+	case hwmon_temp:
+		switch (attr) {
+		case hwmon_temp_input:
+		case hwmon_temp_fault:
+			return 0444;
+		case hwmon_temp_alarm:
+			return 0644;
+		default:
+			break;
+		}
+		break;
+	case hwmon_fan:
+		switch (attr) {
+		case hwmon_fan_input:
+		case hwmon_fan_fault:
+			return 0444;
+		case hwmon_fan_alarm:
+			return 0644;
+		default:
+			break;
+		}
+		break;
+	case hwmon_pwm:
+	case hwmon_in:
+		return 0444;
+	default:
+		break;
+	}
+
+	return 0;
+}
+
+static int fts_read(struct device *dev, enum hwmon_sensor_types type, u32 attr, int channel,
+		    long *val)
+{
+	struct fts_data *data = dev_get_drvdata(dev);
+	int ret = fts_update_device(data);
+
+	if (ret < 0)
+		return ret;
+
+	switch (type) {
+	case hwmon_temp:
+		switch (attr) {
+		case hwmon_temp_input:
+			*val = (data->temp_input[channel] - 64) * 1000;
+
+			return 0;
+		case hwmon_temp_alarm:
+			*val = !!(data->temp_alarm & BIT(channel));
+
+			return 0;
+		case hwmon_temp_fault:
+			/* 00h Temperature = Sensor Error */;
+			*val = (data->temp_input[channel] == 0);
+
+			return 0;
+		default:
+			break;
+		}
+		break;
+	case hwmon_fan:
+		switch (attr) {
+		case hwmon_fan_input:
+			*val = data->fan_input[channel] * 60;
+
+			return 0;
+		case hwmon_fan_alarm:
+			*val = !!(data->fan_alarm & BIT(channel));
+
+			return 0;
+		case hwmon_fan_fault:
+			*val = !(data->fan_present & BIT(channel));
+
+			return 0;
+		default:
+			break;
+		}
+		break;
+	case hwmon_pwm:
+		switch (attr) {
+		case hwmon_pwm_auto_channels_temp: {
+			u8 fan_source = data->fan_source[channel];
+
+			if (fan_source == FTS_FAN_SOURCE_INVALID || fan_source >= BITS_PER_LONG)
+				*val = 0;
+			else
+				*val = BIT(fan_source);
+
+			return 0;
+		}
+		default:
+			break;
+		}
+		break;
+	case hwmon_in:
+		switch (attr) {
+		case hwmon_in_input:
+			*val = DIV_ROUND_CLOSEST(data->volt[channel] * 3300, 255);
+
+			return 0;
+		default:
+			break;
+		}
+		break;
+	default:
+		break;
+	}
+
+	return -EOPNOTSUPP;
+}
+
+static int fts_write(struct device *dev, enum hwmon_sensor_types type, u32 attr, int channel,
+		     long val)
+{
+	struct fts_data *data = dev_get_drvdata(dev);
+	int ret = fts_update_device(data);
+
+	if (ret < 0)
+		return ret;
+
+	switch (type) {
+	case hwmon_temp:
+		switch (attr) {
+		case hwmon_temp_alarm:
+			if (val)
+				return -EINVAL;
+
+			ret = fts_read_byte(data->client, FTS_REG_TEMP_CONTROL(channel));
+			if (ret < 0)
+				return ret;
+			ret = fts_write_byte(data->client, FTS_REG_TEMP_CONTROL(channel),
+					     ret | 0x1);
+			if (ret < 0)
+				return ret;
+			data->valid = false;
+			return 0;
+		default:
+			break;
+		}
+		break;
+	case hwmon_fan:
+		switch (attr) {
+		case hwmon_fan_alarm:
+			if (val)
+				return -EINVAL;
+
+			ret = fts_read_byte(data->client, FTS_REG_FAN_CONTROL(channel));
+			if (ret < 0)
+				return ret;
+			ret = fts_write_byte(data->client, FTS_REG_FAN_CONTROL(channel),
+					     ret | 0x1);
+			if (ret < 0)
+				return ret;
+			data->valid = false;
+			return 0;
+		default:
+			break;
+		}
+		break;
+	default:
+		break;
+	}
+
+	return -EOPNOTSUPP;
+}
+
+static const struct hwmon_ops fts_ops = {
+	.is_visible = fts_is_visible,
+	.read = fts_read,
+	.write = fts_write,
+};
+
+static const struct hwmon_channel_info * const fts_info[] = {
+	HWMON_CHANNEL_INFO(chip, HWMON_C_REGISTER_TZ),
+	HWMON_CHANNEL_INFO(temp,
+			   HWMON_T_INPUT | HWMON_T_ALARM | HWMON_T_FAULT,
+			   HWMON_T_INPUT | HWMON_T_ALARM | HWMON_T_FAULT,
+			   HWMON_T_INPUT | HWMON_T_ALARM | HWMON_T_FAULT,
+			   HWMON_T_INPUT | HWMON_T_ALARM | HWMON_T_FAULT,
+			   HWMON_T_INPUT | HWMON_T_ALARM | HWMON_T_FAULT,
+			   HWMON_T_INPUT | HWMON_T_ALARM | HWMON_T_FAULT,
+			   HWMON_T_INPUT | HWMON_T_ALARM | HWMON_T_FAULT,
+			   HWMON_T_INPUT | HWMON_T_ALARM | HWMON_T_FAULT,
+			   HWMON_T_INPUT | HWMON_T_ALARM | HWMON_T_FAULT,
+			   HWMON_T_INPUT | HWMON_T_ALARM | HWMON_T_FAULT,
+			   HWMON_T_INPUT | HWMON_T_ALARM | HWMON_T_FAULT,
+			   HWMON_T_INPUT | HWMON_T_ALARM | HWMON_T_FAULT,
+			   HWMON_T_INPUT | HWMON_T_ALARM | HWMON_T_FAULT,
+			   HWMON_T_INPUT | HWMON_T_ALARM | HWMON_T_FAULT,
+			   HWMON_T_INPUT | HWMON_T_ALARM | HWMON_T_FAULT,
+			   HWMON_T_INPUT | HWMON_T_ALARM | HWMON_T_FAULT
+			   ),
+	HWMON_CHANNEL_INFO(fan,
+			   HWMON_F_INPUT | HWMON_F_ALARM | HWMON_F_FAULT,
+			   HWMON_F_INPUT | HWMON_F_ALARM | HWMON_F_FAULT,
+			   HWMON_F_INPUT | HWMON_F_ALARM | HWMON_F_FAULT,
+			   HWMON_F_INPUT | HWMON_F_ALARM | HWMON_F_FAULT,
+			   HWMON_F_INPUT | HWMON_F_ALARM | HWMON_F_FAULT,
+			   HWMON_F_INPUT | HWMON_F_ALARM | HWMON_F_FAULT,
+			   HWMON_F_INPUT | HWMON_F_ALARM | HWMON_F_FAULT,
+			   HWMON_F_INPUT | HWMON_F_ALARM | HWMON_F_FAULT
+			   ),
+	HWMON_CHANNEL_INFO(pwm,
+			   HWMON_PWM_AUTO_CHANNELS_TEMP,
+			   HWMON_PWM_AUTO_CHANNELS_TEMP,
+			   HWMON_PWM_AUTO_CHANNELS_TEMP,
+			   HWMON_PWM_AUTO_CHANNELS_TEMP,
+			   HWMON_PWM_AUTO_CHANNELS_TEMP,
+			   HWMON_PWM_AUTO_CHANNELS_TEMP,
+			   HWMON_PWM_AUTO_CHANNELS_TEMP,
+			   HWMON_PWM_AUTO_CHANNELS_TEMP
+			   ),
+	HWMON_CHANNEL_INFO(in,
+			   HWMON_I_INPUT,
+			   HWMON_I_INPUT,
+			   HWMON_I_INPUT,
+			   HWMON_I_INPUT
+			   ),
+	NULL
+};
+
+static const struct hwmon_chip_info fts_chip_info = {
+	.ops = &fts_ops,
+	.info = fts_info,
+};
+
+/*****************************************************************************/
+/* Module initialization / remove functions				     */
+/*****************************************************************************/
+static int fts_detect(struct i2c_client *client,
+		      struct i2c_board_info *info)
+{
+	int val;
+
+	/* detection works with revision greater or equal to 0x2b */
+	val = i2c_smbus_read_byte_data(client, FTS_DEVICE_REVISION_REG);
+	if (val < 0x2b)
+		return -ENODEV;
+
+	/* Device Detect Regs must have 0x17 0x34 and 0x54 */
+	val = i2c_smbus_read_byte_data(client, FTS_DEVICE_DETECT_REG_1);
+	if (val != 0x17)
+		return -ENODEV;
+
+	val = i2c_smbus_read_byte_data(client, FTS_DEVICE_DETECT_REG_2);
+	if (val != 0x34)
+		return -ENODEV;
+
+	val = i2c_smbus_read_byte_data(client, FTS_DEVICE_DETECT_REG_3);
+	if (val != 0x54)
+		return -ENODEV;
+
+	/*
+	 * 0x10 == Baseboard Management Controller, 0x01 == Teutates
+	 * Device ID Reg needs to be 0x11
+	 */
+	val = i2c_smbus_read_byte_data(client, FTS_DEVICE_ID_REG);
+	if (val != 0x11)
+		return -ENODEV;
+
+	strscpy(info->type, fts_id[0].name, I2C_NAME_SIZE);
+	info->flags = 0;
+	return 0;
+}
+
+static int fts_probe(struct i2c_client *client)
+{
+	u8 revision;
+	struct fts_data *data;
+	int err;
+	s8 deviceid;
+	struct device *hwmon_dev;
+
+	if (client->addr != 0x73)
+		return -ENODEV;
+
+	/* Baseboard Management Controller check */
+	deviceid = i2c_smbus_read_byte_data(client, FTS_DEVICE_ID_REG);
+	if (deviceid > 0 && (deviceid & 0xF0) == 0x10) {
+		switch (deviceid & 0x0F) {
+		case 0x01:
+			break;
+		default:
+			dev_dbg(&client->dev,
+				"No Baseboard Management Controller\n");
+			return -ENODEV;
+		}
+	} else {
+		dev_dbg(&client->dev, "No fujitsu board\n");
+		return -ENODEV;
+	}
+
+	data = devm_kzalloc(&client->dev, sizeof(struct fts_data),
+			    GFP_KERNEL);
+	if (!data)
+		return -ENOMEM;
+
+	data->client = client;
+	dev_set_drvdata(&client->dev, data);
+
+	err = i2c_smbus_read_byte_data(client, FTS_DEVICE_REVISION_REG);
+	if (err < 0)
+		return err;
+	revision = err;
+
+	hwmon_dev = devm_hwmon_device_register_with_info(&client->dev, "ftsteutates", data,
+							 &fts_chip_info, NULL);
+	if (IS_ERR(hwmon_dev))
+		return PTR_ERR(hwmon_dev);
+
+	err = fts_watchdog_init(data);
+	if (err)
+		return err;
+
+	dev_info(&client->dev, "Detected FTS Teutates chip, revision: %d.%d\n",
+		 (revision & 0xF0) >> 4, revision & 0x0F);
+	return 0;
+}
+
+/*****************************************************************************/
+/* Module Details							     */
+/*****************************************************************************/
+static struct i2c_driver fts_driver = {
+	.class = I2C_CLASS_HWMON,
+	.driver = {
+		.name = "ftsteutates",
+	},
+	.id_table = fts_id,
+	.probe = fts_probe,
+	.detect = fts_detect,
+	.address_list = normal_i2c,
+};
+
+module_i2c_driver(fts_driver);
+
+MODULE_AUTHOR("Thilo Cestonaro <thilo.cestonaro@ts.fujitsu.com>");
+MODULE_DESCRIPTION("FTS Teutates driver");
+MODULE_LICENSE("GPL");