Merge tag 'trace-v7.3-2' of git://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-tracegrafted

Pull tracing fixes from Steven Rostedt:

 - Fix error output of boot instance creation failure

   Currently if a boot instance creation fails, instead of printing out
   the name of the instance that failed, it prints "(null)". That is
   because it prints "cur_str" that had already been processed by
   strsep(). Print the saved name instead.

   While at it, print the error code of the failure.

 - Fix use-after-free for same named historgrams

   Histograms can be named so that they can be used in multiple events.
   But if the named histogram has a variable attached, the second event
   that uses the named histogram which duplicates it and needs to free
   the original after duplication leaves the old variable in place and
   still visible. If another histogram uses than variable, it will use
   the stale one which will try to reference the freed duplicate
   histogram and crash the kernel.

   Free the duplicate variables along with the duplicated histogram
   data.

 - Check return value of kthread_run() in event self test

   The events self tests uses a kthread for testing but does not check
   if it succeeded in creating a kthread. If the kthread creation were
   to fail, the code will still try to call kthread_stop() on the error
   returned.

 - Fix race between reading trace_pipe and updating subbuffer size

   If a user is reading the trace_pipe file at the same time they update
   the ring buffer sub-buffer size, can cause the trace_pipe read to
   read stale data. Add trace_access_lock() around updating the ring
   buffer sub-buffer size.

 - Fix eventfs_inode on failure path in creation of the events directory

   In the creation of the "events" directory, if after allocating the
   eventfs_inode a failure is detected, it calls cleanup_ei() which
   calls free_ei(). The free_ei() will test if eventfs_inode being freed
   has no children. It is a bug if it does. But on the failure case of
   the creation of the "events" directory, the children lists have not
   yet been initialized and the free will trigger a warning because
   list_empty() on an uninitialized list returns false.

   Move the initialization into init_ei() where it makes more sense and
   makes sure that a created eventfs_inode has its lists initialized
   upon creation.

 - Check return value of kthread_run() in ftrace direct sample code

   The sample code that shows how to use the ftrace direct calls does
   not test the return of kthread_run() to see if it succeeds. Return a
   failure if the kthread_run() doesn't succeed.

 - Clear user events state on fork in case of alloc failure

   On fork, the child gets a pointer to the parent's user events state.
   It makes a copy of it then updates the child's pointer to it. But if
   the allocation fails, the duplication function leaves the child with
   a pointer to its parent's descriptor. When the child cleans up its
   data, it will free the parent's descriptor while the parent is still
   using it.

   In the duplication function, set the child's user_event_mm to NULL
   before testing if the allocation succeeded, and when it exits it will
   not free the parent's descriptor.

 - Fix retry exhaustion in simple ring buffer reader swap

   simple_ring_buffer_swap_reader_page() starts with retry set to 8 and
   post-decrements it only after a failed link replacement. On the final
   attempt, a successful replacement leaves retry at zero, while a
   failed replacement leaves it at -1.

   But the check for success expects the retry value to be non-zero and
   exits with an error on zero. This is the opposite result. Fix it.

 - Fail nicely when the remote swap_reader_page() returns an error

   Currently, if the swap_reader_page() of a remote buffer fails, it
   triggers a WARN_ON_ONCE() and continues normally. Instead, have it
   exit with an error and a pr_warn() print instead of a full WARNING.

* tag 'trace-v7.3-2' of git://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-trace:
  ring-buffer: Stop remote reader update when page swap fails
  tracing: Fix retry exhaustion in simple ring buffer reader swap
  tracing/user_events: Clear copied tracing state before fork duplication
  samples/ftrace: Fix kthread_stop() on ERR_PTR in ftrace-direct-multi-modify
  samples/ftrace: Fix kthread_stop() on ERR_PTR in ftrace-direct-modify
  eventfs: Initialize ei->children and ei->list in init_ei()
  tracing: Fix use-after-free in trace_pipe read on sub-buffer order change
  tracing: Fix crash passing ERR_PTR to kthread_stop()
  tracing: Fix use-after-free with same-name named triggers
  tracing: Fix logged instance name on creation failure

1 files changed, 670 insertions, 0 deletions

diff --git a/drivers/hwmon/emc2103.c b/drivers/hwmon/emc2103.c
new file mode 100644
index 000000000..27dc149a3
--- /dev/null
+++ b/drivers/hwmon/emc2103.c
@@ -0,0 +1,670 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * emc2103.c - Support for SMSC EMC2103
+ * Copyright (c) 2010 SMSC
+ */
+
+#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 scanned */
+static const unsigned short normal_i2c[] = { 0x2E, I2C_CLIENT_END };
+
+static const u8 REG_TEMP[4] = { 0x00, 0x02, 0x04, 0x06 };
+static const u8 REG_TEMP_MIN[4] = { 0x3c, 0x38, 0x39, 0x3a };
+static const u8 REG_TEMP_MAX[4] = { 0x34, 0x30, 0x31, 0x32 };
+
+#define REG_CONF1		0x20
+#define REG_TEMP_MAX_ALARM	0x24
+#define REG_TEMP_MIN_ALARM	0x25
+#define REG_FAN_CONF1		0x42
+#define REG_FAN_TARGET_LO	0x4c
+#define REG_FAN_TARGET_HI	0x4d
+#define REG_FAN_TACH_HI		0x4e
+#define REG_FAN_TACH_LO		0x4f
+#define REG_PRODUCT_ID		0xfd
+#define REG_MFG_ID		0xfe
+
+/* equation 4 from datasheet: rpm = (3932160 * multipler) / count */
+#define FAN_RPM_FACTOR		3932160
+
+/*
+ * 2103-2 and 2103-4's 3rd temperature sensor can be connected to two diodes
+ * in anti-parallel mode, and in this configuration both can be read
+ * independently (so we have 4 temperature inputs).  The device can't
+ * detect if it's connected in this mode, so we have to manually enable
+ * it.  Default is to leave the device in the state it's already in (-1).
+ * This parameter allows APD mode to be optionally forced on or off
+ */
+static int apd = -1;
+module_param(apd, bint, 0);
+MODULE_PARM_DESC(apd, "Set to zero to disable anti-parallel diode mode");
+
+struct temperature {
+	s8	degrees;
+	u8	fraction;	/* 0-7 multiples of 0.125 */
+};
+
+struct emc2103_data {
+	struct i2c_client	*client;
+	const struct		attribute_group *groups[4];
+	struct mutex		update_lock;
+	bool			valid;		/* registers are valid */
+	bool			fan_rpm_control;
+	int			temp_count;	/* num of temp sensors */
+	unsigned long		last_updated;	/* in jiffies */
+	struct temperature	temp[4];	/* internal + 3 external */
+	s8			temp_min[4];	/* no fractional part */
+	s8			temp_max[4];    /* no fractional part */
+	u8			temp_min_alarm;
+	u8			temp_max_alarm;
+	u8			fan_multiplier;
+	u16			fan_tach;
+	u16			fan_target;
+};
+
+static int read_u8_from_i2c(struct i2c_client *client, u8 i2c_reg, u8 *output)
+{
+	int status = i2c_smbus_read_byte_data(client, i2c_reg);
+	if (status < 0) {
+		dev_warn(&client->dev, "reg 0x%02x, err %d\n",
+			i2c_reg, status);
+	} else {
+		*output = status;
+	}
+	return status;
+}
+
+static void read_temp_from_i2c(struct i2c_client *client, u8 i2c_reg,
+			       struct temperature *temp)
+{
+	u8 degrees, fractional;
+
+	if (read_u8_from_i2c(client, i2c_reg, &degrees) < 0)
+		return;
+
+	if (read_u8_from_i2c(client, i2c_reg + 1, &fractional) < 0)
+		return;
+
+	temp->degrees = degrees;
+	temp->fraction = (fractional & 0xe0) >> 5;
+}
+
+static void read_fan_from_i2c(struct i2c_client *client, u16 *output,
+			      u8 hi_addr, u8 lo_addr)
+{
+	u8 high_byte, lo_byte;
+
+	if (read_u8_from_i2c(client, hi_addr, &high_byte) < 0)
+		return;
+
+	if (read_u8_from_i2c(client, lo_addr, &lo_byte) < 0)
+		return;
+
+	*output = ((u16)high_byte << 5) | (lo_byte >> 3);
+}
+
+static void write_fan_target_to_i2c(struct i2c_client *client, u16 new_target)
+{
+	u8 high_byte = (new_target & 0x1fe0) >> 5;
+	u8 low_byte = (new_target & 0x001f) << 3;
+	i2c_smbus_write_byte_data(client, REG_FAN_TARGET_LO, low_byte);
+	i2c_smbus_write_byte_data(client, REG_FAN_TARGET_HI, high_byte);
+}
+
+static void read_fan_config_from_i2c(struct i2c_client *client)
+
+{
+	struct emc2103_data *data = i2c_get_clientdata(client);
+	u8 conf1;
+
+	if (read_u8_from_i2c(client, REG_FAN_CONF1, &conf1) < 0)
+		return;
+
+	data->fan_multiplier = 1 << ((conf1 & 0x60) >> 5);
+	data->fan_rpm_control = (conf1 & 0x80) != 0;
+}
+
+static struct emc2103_data *emc2103_update_device(struct device *dev)
+{
+	struct emc2103_data *data = dev_get_drvdata(dev);
+	struct i2c_client *client = data->client;
+
+	mutex_lock(&data->update_lock);
+
+	if (time_after(jiffies, data->last_updated + HZ + HZ / 2)
+	    || !data->valid) {
+		int i;
+
+		for (i = 0; i < data->temp_count; i++) {
+			read_temp_from_i2c(client, REG_TEMP[i], &data->temp[i]);
+			read_u8_from_i2c(client, REG_TEMP_MIN[i],
+				&data->temp_min[i]);
+			read_u8_from_i2c(client, REG_TEMP_MAX[i],
+				&data->temp_max[i]);
+		}
+
+		read_u8_from_i2c(client, REG_TEMP_MIN_ALARM,
+			&data->temp_min_alarm);
+		read_u8_from_i2c(client, REG_TEMP_MAX_ALARM,
+			&data->temp_max_alarm);
+
+		read_fan_from_i2c(client, &data->fan_tach,
+			REG_FAN_TACH_HI, REG_FAN_TACH_LO);
+		read_fan_from_i2c(client, &data->fan_target,
+			REG_FAN_TARGET_HI, REG_FAN_TARGET_LO);
+		read_fan_config_from_i2c(client);
+
+		data->last_updated = jiffies;
+		data->valid = true;
+	}
+
+	mutex_unlock(&data->update_lock);
+
+	return data;
+}
+
+static ssize_t
+temp_show(struct device *dev, struct device_attribute *da, char *buf)
+{
+	int nr = to_sensor_dev_attr(da)->index;
+	struct emc2103_data *data = emc2103_update_device(dev);
+	int millidegrees = data->temp[nr].degrees * 1000
+		+ data->temp[nr].fraction * 125;
+	return sprintf(buf, "%d\n", millidegrees);
+}
+
+static ssize_t
+temp_min_show(struct device *dev, struct device_attribute *da, char *buf)
+{
+	int nr = to_sensor_dev_attr(da)->index;
+	struct emc2103_data *data = emc2103_update_device(dev);
+	int millidegrees = data->temp_min[nr] * 1000;
+	return sprintf(buf, "%d\n", millidegrees);
+}
+
+static ssize_t
+temp_max_show(struct device *dev, struct device_attribute *da, char *buf)
+{
+	int nr = to_sensor_dev_attr(da)->index;
+	struct emc2103_data *data = emc2103_update_device(dev);
+	int millidegrees = data->temp_max[nr] * 1000;
+	return sprintf(buf, "%d\n", millidegrees);
+}
+
+static ssize_t
+temp_fault_show(struct device *dev, struct device_attribute *da, char *buf)
+{
+	int nr = to_sensor_dev_attr(da)->index;
+	struct emc2103_data *data = emc2103_update_device(dev);
+	bool fault = (data->temp[nr].degrees == -128);
+	return sprintf(buf, "%d\n", fault ? 1 : 0);
+}
+
+static ssize_t
+temp_min_alarm_show(struct device *dev, struct device_attribute *da,
+		    char *buf)
+{
+	int nr = to_sensor_dev_attr(da)->index;
+	struct emc2103_data *data = emc2103_update_device(dev);
+	bool alarm = data->temp_min_alarm & (1 << nr);
+	return sprintf(buf, "%d\n", alarm ? 1 : 0);
+}
+
+static ssize_t
+temp_max_alarm_show(struct device *dev, struct device_attribute *da,
+		    char *buf)
+{
+	int nr = to_sensor_dev_attr(da)->index;
+	struct emc2103_data *data = emc2103_update_device(dev);
+	bool alarm = data->temp_max_alarm & (1 << nr);
+	return sprintf(buf, "%d\n", alarm ? 1 : 0);
+}
+
+static ssize_t temp_min_store(struct device *dev, struct device_attribute *da,
+			      const char *buf, size_t count)
+{
+	int nr = to_sensor_dev_attr(da)->index;
+	struct emc2103_data *data = dev_get_drvdata(dev);
+	struct i2c_client *client = data->client;
+	long val;
+
+	int result = kstrtol(buf, 10, &val);
+	if (result < 0)
+		return result;
+
+	val = DIV_ROUND_CLOSEST(clamp_val(val, -63000, 127000), 1000);
+
+	mutex_lock(&data->update_lock);
+	data->temp_min[nr] = val;
+	i2c_smbus_write_byte_data(client, REG_TEMP_MIN[nr], val);
+	mutex_unlock(&data->update_lock);
+
+	return count;
+}
+
+static ssize_t temp_max_store(struct device *dev, struct device_attribute *da,
+			      const char *buf, size_t count)
+{
+	int nr = to_sensor_dev_attr(da)->index;
+	struct emc2103_data *data = dev_get_drvdata(dev);
+	struct i2c_client *client = data->client;
+	long val;
+
+	int result = kstrtol(buf, 10, &val);
+	if (result < 0)
+		return result;
+
+	val = DIV_ROUND_CLOSEST(clamp_val(val, -63000, 127000), 1000);
+
+	mutex_lock(&data->update_lock);
+	data->temp_max[nr] = val;
+	i2c_smbus_write_byte_data(client, REG_TEMP_MAX[nr], val);
+	mutex_unlock(&data->update_lock);
+
+	return count;
+}
+
+static ssize_t
+fan1_input_show(struct device *dev, struct device_attribute *da, char *buf)
+{
+	struct emc2103_data *data = emc2103_update_device(dev);
+	int rpm = 0;
+	mutex_lock(&data->update_lock);
+	if (data->fan_tach != 0)
+		rpm = (FAN_RPM_FACTOR * data->fan_multiplier) / data->fan_tach;
+	mutex_unlock(&data->update_lock);
+	return sprintf(buf, "%d\n", rpm);
+}
+
+static ssize_t
+fan1_div_show(struct device *dev, struct device_attribute *da, char *buf)
+{
+	struct emc2103_data *data = emc2103_update_device(dev);
+	int fan_div = 8 / data->fan_multiplier;
+	return sprintf(buf, "%d\n", fan_div);
+}
+
+/*
+ * Note: we also update the fan target here, because its value is
+ * determined in part by the fan clock divider.  This follows the principle
+ * of least surprise; the user doesn't expect the fan target to change just
+ * because the divider changed.
+ */
+static ssize_t fan1_div_store(struct device *dev, struct device_attribute *da,
+			      const char *buf, size_t count)
+{
+	struct emc2103_data *data = emc2103_update_device(dev);
+	struct i2c_client *client = data->client;
+	int new_range_bits, old_div = 8 / data->fan_multiplier;
+	long new_div;
+
+	int status = kstrtol(buf, 10, &new_div);
+	if (status < 0)
+		return status;
+
+	if (new_div == old_div) /* No change */
+		return count;
+
+	switch (new_div) {
+	case 1:
+		new_range_bits = 3;
+		break;
+	case 2:
+		new_range_bits = 2;
+		break;
+	case 4:
+		new_range_bits = 1;
+		break;
+	case 8:
+		new_range_bits = 0;
+		break;
+	default:
+		return -EINVAL;
+	}
+
+	mutex_lock(&data->update_lock);
+
+	status = i2c_smbus_read_byte_data(client, REG_FAN_CONF1);
+	if (status < 0) {
+		dev_dbg(&client->dev, "reg 0x%02x, err %d\n",
+			REG_FAN_CONF1, status);
+		mutex_unlock(&data->update_lock);
+		return status;
+	}
+	status &= 0x9F;
+	status |= (new_range_bits << 5);
+	i2c_smbus_write_byte_data(client, REG_FAN_CONF1, status);
+
+	data->fan_multiplier = 8 / new_div;
+
+	/* update fan target if high byte is not disabled */
+	if ((data->fan_target & 0x1fe0) != 0x1fe0) {
+		u16 new_target = (data->fan_target * old_div) / new_div;
+		data->fan_target = min(new_target, (u16)0x1fff);
+		write_fan_target_to_i2c(client, data->fan_target);
+	}
+
+	/* invalidate data to force re-read from hardware */
+	data->valid = false;
+
+	mutex_unlock(&data->update_lock);
+	return count;
+}
+
+static ssize_t
+fan1_target_show(struct device *dev, struct device_attribute *da, char *buf)
+{
+	struct emc2103_data *data = emc2103_update_device(dev);
+	int rpm = 0;
+
+	mutex_lock(&data->update_lock);
+	/* high byte of 0xff indicates disabled so return 0 */
+	if ((data->fan_target != 0) && ((data->fan_target & 0x1fe0) != 0x1fe0))
+		rpm = (FAN_RPM_FACTOR * data->fan_multiplier)
+			/ data->fan_target;
+	mutex_unlock(&data->update_lock);
+
+	return sprintf(buf, "%d\n", rpm);
+}
+
+static ssize_t fan1_target_store(struct device *dev,
+				 struct device_attribute *da, const char *buf,
+				 size_t count)
+{
+	struct emc2103_data *data = emc2103_update_device(dev);
+	struct i2c_client *client = data->client;
+	unsigned long rpm_target;
+
+	int result = kstrtoul(buf, 10, &rpm_target);
+	if (result < 0)
+		return result;
+
+	/* Datasheet states 16384 as maximum RPM target (table 3.2) */
+	rpm_target = clamp_val(rpm_target, 0, 16384);
+
+	mutex_lock(&data->update_lock);
+
+	if (rpm_target == 0)
+		data->fan_target = 0x1fff;
+	else
+		data->fan_target = clamp_val(
+			(FAN_RPM_FACTOR * data->fan_multiplier) / rpm_target,
+			0, 0x1fff);
+
+	write_fan_target_to_i2c(client, data->fan_target);
+
+	mutex_unlock(&data->update_lock);
+	return count;
+}
+
+static ssize_t
+fan1_fault_show(struct device *dev, struct device_attribute *da, char *buf)
+{
+	struct emc2103_data *data = emc2103_update_device(dev);
+	bool fault = ((data->fan_tach & 0x1fe0) == 0x1fe0);
+	return sprintf(buf, "%d\n", fault ? 1 : 0);
+}
+
+static ssize_t
+pwm1_enable_show(struct device *dev, struct device_attribute *da, char *buf)
+{
+	struct emc2103_data *data = emc2103_update_device(dev);
+	return sprintf(buf, "%d\n", data->fan_rpm_control ? 3 : 0);
+}
+
+static ssize_t pwm1_enable_store(struct device *dev,
+				 struct device_attribute *da, const char *buf,
+				 size_t count)
+{
+	struct emc2103_data *data = dev_get_drvdata(dev);
+	struct i2c_client *client = data->client;
+	long new_value;
+	u8 conf_reg;
+
+	int result = kstrtol(buf, 10, &new_value);
+	if (result < 0)
+		return result;
+
+	mutex_lock(&data->update_lock);
+	switch (new_value) {
+	case 0:
+		data->fan_rpm_control = false;
+		break;
+	case 3:
+		data->fan_rpm_control = true;
+		break;
+	default:
+		count = -EINVAL;
+		goto err;
+	}
+
+	result = read_u8_from_i2c(client, REG_FAN_CONF1, &conf_reg);
+	if (result < 0) {
+		count = result;
+		goto err;
+	}
+
+	if (data->fan_rpm_control)
+		conf_reg |= 0x80;
+	else
+		conf_reg &= ~0x80;
+
+	i2c_smbus_write_byte_data(client, REG_FAN_CONF1, conf_reg);
+err:
+	mutex_unlock(&data->update_lock);
+	return count;
+}
+
+static SENSOR_DEVICE_ATTR_RO(temp1_input, temp, 0);
+static SENSOR_DEVICE_ATTR_RW(temp1_min, temp_min, 0);
+static SENSOR_DEVICE_ATTR_RW(temp1_max, temp_max, 0);
+static SENSOR_DEVICE_ATTR_RO(temp1_fault, temp_fault, 0);
+static SENSOR_DEVICE_ATTR_RO(temp1_min_alarm, temp_min_alarm, 0);
+static SENSOR_DEVICE_ATTR_RO(temp1_max_alarm, temp_max_alarm, 0);
+
+static SENSOR_DEVICE_ATTR_RO(temp2_input, temp, 1);
+static SENSOR_DEVICE_ATTR_RW(temp2_min, temp_min, 1);
+static SENSOR_DEVICE_ATTR_RW(temp2_max, temp_max, 1);
+static SENSOR_DEVICE_ATTR_RO(temp2_fault, temp_fault, 1);
+static SENSOR_DEVICE_ATTR_RO(temp2_min_alarm, temp_min_alarm, 1);
+static SENSOR_DEVICE_ATTR_RO(temp2_max_alarm, temp_max_alarm, 1);
+
+static SENSOR_DEVICE_ATTR_RO(temp3_input, temp, 2);
+static SENSOR_DEVICE_ATTR_RW(temp3_min, temp_min, 2);
+static SENSOR_DEVICE_ATTR_RW(temp3_max, temp_max, 2);
+static SENSOR_DEVICE_ATTR_RO(temp3_fault, temp_fault, 2);
+static SENSOR_DEVICE_ATTR_RO(temp3_min_alarm, temp_min_alarm, 2);
+static SENSOR_DEVICE_ATTR_RO(temp3_max_alarm, temp_max_alarm, 2);
+
+static SENSOR_DEVICE_ATTR_RO(temp4_input, temp, 3);
+static SENSOR_DEVICE_ATTR_RW(temp4_min, temp_min, 3);
+static SENSOR_DEVICE_ATTR_RW(temp4_max, temp_max, 3);
+static SENSOR_DEVICE_ATTR_RO(temp4_fault, temp_fault, 3);
+static SENSOR_DEVICE_ATTR_RO(temp4_min_alarm, temp_min_alarm, 3);
+static SENSOR_DEVICE_ATTR_RO(temp4_max_alarm, temp_max_alarm, 3);
+
+static DEVICE_ATTR_RO(fan1_input);
+static DEVICE_ATTR_RW(fan1_div);
+static DEVICE_ATTR_RW(fan1_target);
+static DEVICE_ATTR_RO(fan1_fault);
+
+static DEVICE_ATTR_RW(pwm1_enable);
+
+/* sensors present on all models */
+static struct attribute *emc2103_attributes[] = {
+	&sensor_dev_attr_temp1_input.dev_attr.attr,
+	&sensor_dev_attr_temp1_min.dev_attr.attr,
+	&sensor_dev_attr_temp1_max.dev_attr.attr,
+	&sensor_dev_attr_temp1_fault.dev_attr.attr,
+	&sensor_dev_attr_temp1_min_alarm.dev_attr.attr,
+	&sensor_dev_attr_temp1_max_alarm.dev_attr.attr,
+	&sensor_dev_attr_temp2_input.dev_attr.attr,
+	&sensor_dev_attr_temp2_min.dev_attr.attr,
+	&sensor_dev_attr_temp2_max.dev_attr.attr,
+	&sensor_dev_attr_temp2_fault.dev_attr.attr,
+	&sensor_dev_attr_temp2_min_alarm.dev_attr.attr,
+	&sensor_dev_attr_temp2_max_alarm.dev_attr.attr,
+	&dev_attr_fan1_input.attr,
+	&dev_attr_fan1_div.attr,
+	&dev_attr_fan1_target.attr,
+	&dev_attr_fan1_fault.attr,
+	&dev_attr_pwm1_enable.attr,
+	NULL
+};
+
+/* extra temperature sensors only present on 2103-2 and 2103-4 */
+static struct attribute *emc2103_attributes_temp3[] = {
+	&sensor_dev_attr_temp3_input.dev_attr.attr,
+	&sensor_dev_attr_temp3_min.dev_attr.attr,
+	&sensor_dev_attr_temp3_max.dev_attr.attr,
+	&sensor_dev_attr_temp3_fault.dev_attr.attr,
+	&sensor_dev_attr_temp3_min_alarm.dev_attr.attr,
+	&sensor_dev_attr_temp3_max_alarm.dev_attr.attr,
+	NULL
+};
+
+/* extra temperature sensors only present on 2103-2 and 2103-4 in APD mode */
+static struct attribute *emc2103_attributes_temp4[] = {
+	&sensor_dev_attr_temp4_input.dev_attr.attr,
+	&sensor_dev_attr_temp4_min.dev_attr.attr,
+	&sensor_dev_attr_temp4_max.dev_attr.attr,
+	&sensor_dev_attr_temp4_fault.dev_attr.attr,
+	&sensor_dev_attr_temp4_min_alarm.dev_attr.attr,
+	&sensor_dev_attr_temp4_max_alarm.dev_attr.attr,
+	NULL
+};
+
+static const struct attribute_group emc2103_group = {
+	.attrs = emc2103_attributes,
+};
+
+static const struct attribute_group emc2103_temp3_group = {
+	.attrs = emc2103_attributes_temp3,
+};
+
+static const struct attribute_group emc2103_temp4_group = {
+	.attrs = emc2103_attributes_temp4,
+};
+
+static int
+emc2103_probe(struct i2c_client *client)
+{
+	struct emc2103_data *data;
+	struct device *hwmon_dev;
+	int status, idx = 0;
+
+	if (!i2c_check_functionality(client->adapter, I2C_FUNC_SMBUS_BYTE_DATA))
+		return -EIO;
+
+	data = devm_kzalloc(&client->dev, sizeof(struct emc2103_data),
+			    GFP_KERNEL);
+	if (!data)
+		return -ENOMEM;
+
+	i2c_set_clientdata(client, data);
+	data->client = client;
+	mutex_init(&data->update_lock);
+
+	/* 2103-2 and 2103-4 have 3 external diodes, 2103-1 has 1 */
+	status = i2c_smbus_read_byte_data(client, REG_PRODUCT_ID);
+	if (status == 0x24) {
+		/* 2103-1 only has 1 external diode */
+		data->temp_count = 2;
+	} else {
+		/* 2103-2 and 2103-4 have 3 or 4 external diodes */
+		status = i2c_smbus_read_byte_data(client, REG_CONF1);
+		if (status < 0) {
+			dev_dbg(&client->dev, "reg 0x%02x, err %d\n", REG_CONF1,
+				status);
+			return status;
+		}
+
+		/* detect current state of hardware */
+		data->temp_count = (status & 0x01) ? 4 : 3;
+
+		/* force APD state if module parameter is set */
+		if (apd == 0) {
+			/* force APD mode off */
+			data->temp_count = 3;
+			status &= ~(0x01);
+			i2c_smbus_write_byte_data(client, REG_CONF1, status);
+		} else if (apd == 1) {
+			/* force APD mode on */
+			data->temp_count = 4;
+			status |= 0x01;
+			i2c_smbus_write_byte_data(client, REG_CONF1, status);
+		}
+	}
+
+	/* sysfs hooks */
+	data->groups[idx++] = &emc2103_group;
+	if (data->temp_count >= 3)
+		data->groups[idx++] = &emc2103_temp3_group;
+	if (data->temp_count == 4)
+		data->groups[idx++] = &emc2103_temp4_group;
+
+	hwmon_dev = devm_hwmon_device_register_with_groups(&client->dev,
+							   client->name, data,
+							   data->groups);
+	if (IS_ERR(hwmon_dev))
+		return PTR_ERR(hwmon_dev);
+
+	dev_info(&client->dev, "%s: sensor '%s'\n",
+		 dev_name(hwmon_dev), client->name);
+
+	return 0;
+}
+
+static const struct i2c_device_id emc2103_ids[] = {
+	{ .name = "emc2103" },
+	{ /* LIST END */ }
+};
+MODULE_DEVICE_TABLE(i2c, emc2103_ids);
+
+/* Return 0 if detection is successful, -ENODEV otherwise */
+static int
+emc2103_detect(struct i2c_client *new_client, struct i2c_board_info *info)
+{
+	struct i2c_adapter *adapter = new_client->adapter;
+	int manufacturer, product;
+
+	if (!i2c_check_functionality(adapter, I2C_FUNC_SMBUS_BYTE_DATA))
+		return -ENODEV;
+
+	manufacturer = i2c_smbus_read_byte_data(new_client, REG_MFG_ID);
+	if (manufacturer != 0x5D)
+		return -ENODEV;
+
+	product = i2c_smbus_read_byte_data(new_client, REG_PRODUCT_ID);
+	if ((product != 0x24) && (product != 0x26))
+		return -ENODEV;
+
+	strscpy(info->type, "emc2103", I2C_NAME_SIZE);
+
+	return 0;
+}
+
+static struct i2c_driver emc2103_driver = {
+	.class		= I2C_CLASS_HWMON,
+	.driver = {
+		.name	= "emc2103",
+	},
+	.probe		= emc2103_probe,
+	.id_table	= emc2103_ids,
+	.detect		= emc2103_detect,
+	.address_list	= normal_i2c,
+};
+
+module_i2c_driver(emc2103_driver);
+
+MODULE_AUTHOR("Steve Glendinning <steve.glendinning@shawell.net>");
+MODULE_DESCRIPTION("SMSC EMC2103 hwmon driver");
+MODULE_LICENSE("GPL");