Merge tag 'trace-v7.3-rc2' of git://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-tracegrafted

Pull tracing fixes from Steven Rostedt:

 - Don't destroy user event fields when removal fails

   User event fields are destroyed before the event is removed from
   visibility. But that can fail leaving the still visible event with no
   fields. Move the destroying of the fields to after the event is
   successfully removed from visibility.

 - Initialize function graph state is fork before calling
   copy_exec_state()

   For non-CLONE_VM forks, copy_exec_state() allocates a new
   task_exec_state. If that allocation fails, ftrace_graph_exit_task()
   will free the tasks ret_stack pointer. Since that pointer is still
   using the parent's ret_stack, it mistakenly frees the parent's
   pointer too.

   Call ftrace_graph_init() on the task first which will NULL out the
   new tasks's ret_stack and if the copy fails, it will not free
   anything.

 - Remove FGRAPH_MAX_INDEX

   The macro FGRAPH_MAX_INDEX was added but never used. Remove it.

 - Save ent_size in function graph printing of nested functions

   The function graph tracer needs to look at the next event to see if
   the next event is the return of the current function entry. If it is,
   it prints a single line:

	ktime_get();

   Otherwise it prints it like a nested function:

	tick_nohz_irq_exit() {
	    ktime_get();
	    kcpustat_irq_exit();
	}

   In order to look at the next event, it must save the current event so
   that it has the information to print from it. It saves the event in
   the iterator descriptor called "ent". What it doesn't save is the
   ent_size of the event which is now used to know if the function graph
   arguments are to be printed. The peek doesn't save the size so the
   size used happens to be that of the size of the last event that was
   seen.

   Save the entry event size in the iterator descriptor so that the
   correct size is used.

 - Fix several errors with freeing data in the histogram code

   The histogram code had a lot of leaked or or incorrect accounting
   when failures happen. Correct them.

 - Fix histogram regression of .percent and .graph modifiers

   Up until 6.3 histogram values could have "percent" or "graph"
   modifiers that changed how they were printed. But a change that added
   restricting histograms values from being strings, stack traces and
   other modifiers inadvertently prevented them from using the percent
   and graph modifiers, which were legal use cases for values.

   Put back the percent and graph modifiers.

 - Fix various typos in the comments

 - Set the trace_clock before initializing a histogram with clock
   argument

   The histogram API allows the user to specific which trace clock to
   use via a "clock=" string. The histogram is set up first before the
   clock is checked. If the passed in clock is not valid, it exits
   without fully fixing up the histogram leaving it on the list and a
   use-after-free can trigger.

   Update the clock argument first and if it fails then exit gracefully
   before the histogram trigger is placed on any lists.

 - Restore :mod: trailer after parsing in ftrace_set_clr_event

   The function ftrace_set_clr_event() modifies the parse string and
   needs to put it back to what was passed in. It searches for ":mod:"
   via a strsep() but fails to put back the first ':' in the string.

   Add back the ':' in the passed in string.

 - Take trace_array reference when opening a tracer options file

   The options files are dynamically created and some tracers add their
   own options. When a tracer adds their own list of options, the
   trace_array holding them has an array to hold the list of options for
   each tracer. This array increases in size via a krealloc(), and the
   new entry gets a newly allocated array to hold the options of the new
   tracer being added.

   The element in each entry of the tracer's option array holds a
   pointer back to the trace_array, a pointer to the tracer it is
   associated to, a pointer to the flags of the option.

   The issue is that these arrays are freed when the trace_array is
   freed when its instance it represents is removed from the instances
   directory. There's a race that an open of one of these options files
   can happen when the instance is being removed.

   Add a new helper function to be called by the open function of the
   options file to iterate all existing trace_arrays under a lock and
   find the one that has the given option element in one of it's tracer
   arrays. If found, then update the associated trace_array's reference
   counter to keep it from being freed. If not found, have the open call
   return -ENODEV.

 - Disable interrupts when acquiring the lock in rb_wake_up_waiters()

   The function rb_wake_up_waiters() assumes it will be called in
   interrupt context and does not disable irqs when taking
   cpu_buffer->reader_lock, which can be called in hard interrupt
   context. The issue is in PREEMPT_RT, this function is called in
   thread context leaving this lock open to a deadlock.

   Take the lock with interrupts disabled.

 - Use rcu_assign_pointer() for tmp_ops filter hash

   The tmp_ops used in update_ftrace_direct_mod() assigns its
   filter_hash field directly, but that field is annotated as __rcu and
   sparse complains. Assign it with rcu_assign_pointer()

 - Fix use-after-free in enable_trigger_private_data_free()

   The trace_event_call is accessed through the event_trigger_data's
   trace_event_file pointer to put the trace_event_call on freeing. The
   issue is that the trace_event_file data may have been freed already
   causing a use-after-free. Add a field to the event_trigger_data that
   points directly to the trace_event_call so that it can decrement its
   reference directly without needing to go through the
   trace_event_file.

 - Fix accounting of buffer data remote headers

   trace_buffer_desc_size() and trace_remote_alloc_buffer() undercount
   the number of pages is needed for the asked for size as it doesn't
   take into account the meta data on each page. Add a helper function
   to do the calculation properly and use that in these functions.

 - Catch nr_page_va overflow in ring_buffer_desc sizing

   The number of pages per remote ring buffer is capped by
   ring_buffer_desc::nr_page_va (32 bits). A buffer_size large enough to
   overflow that field would silently allocate a descriptor smaller than
   what was asked for.

 - Do not resize the subbuf order if any per_cpu buffer is disabled

   The mmapping of ring buffers disables resizing the subbuffers, but it
   is done per-cpu whereas the subbuf size change is done for all the
   per_cpu buffers under the buffer->mutex. It could change the size of
   some while the mapping is happening on others. Have the resize of the
   subbuf order check all the per_cpu buffers under the lock to see if
   any of them is disabled before starting and causing an inconsistency
   between buffers that are being mapped.

* tag 'trace-v7.3-rc2' of git://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-trace: (25 commits)
  ring-buffer: Check resize_disabled before publishing the new subbuf order
  tracing/remotes: Catch nr_page_va overflow in ring_buffer_desc sizing
  tracing/remotes: Account for ring buffer page header in size calculation
  tracing: Don't dereference trace_event_file in deferred trigger free
  ftrace: Use rcu_assign_pointer() for tmp_ops filter hash
  ring-buffer: Acquire the lock with irqsave in rb_wake_up_waiters()
  tracing: Take trace_array reference when opening a tracer options file
  tracing: Fix ring_buffer_read_page_size() kernel-doc
  tracing: Restore :mod: trailer after parsing in ftrace_set_clr_event()
  tracing: Fix memory corruption from a "STACKTRACE" histogram key
  tracing: Fix memory corruption from the histogram stacktrace modifier
  tracing: Undo the registration when enabling the histogram trigger fails
  tracing: Take the reference before publishing the named histogram trigger
  tracing: Set the trace clock before registering the histogram trigger
  tracing: Fix typo "preceeded" in comment
  tracing: Fix typo "availabe" in comment
  tracing: Let histogram values keep the percent and graph modifiers
  tracing: Keep the entry count when the histogram stats allocation fails
  tracing: Free histogram the field rejected for a bad modifier
  tracing: Free histogram the var ref when its initialization fails
  ...

1 files changed, 834 insertions, 0 deletions

diff --git a/drivers/hwmon/stts751.c b/drivers/hwmon/stts751.c
new file mode 100644
index 000000000..ce23681f7
--- /dev/null
+++ b/drivers/hwmon/stts751.c
@@ -0,0 +1,834 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * STTS751 sensor driver
+ *
+ * Copyright (C) 2016-2017 Istituto Italiano di Tecnologia - RBCS - EDL
+ * Robotics, Brain and Cognitive Sciences department
+ * Electronic Design Laboratory
+ *
+ * Written by Andrea Merello <andrea.merello@gmail.com>
+ *
+ * Based on  LM95241 driver and LM90 driver
+ */
+
+#include <linux/bitops.h>
+#include <linux/err.h>
+#include <linux/hwmon.h>
+#include <linux/hwmon-sysfs.h>
+#include <linux/i2c.h>
+#include <linux/init.h>
+#include <linux/interrupt.h>
+#include <linux/jiffies.h>
+#include <linux/module.h>
+#include <linux/mutex.h>
+#include <linux/property.h>
+#include <linux/slab.h>
+#include <linux/sysfs.h>
+#include <linux/util_macros.h>
+
+#define DEVNAME "stts751"
+
+static const unsigned short normal_i2c[] = {
+	0x48, 0x49, 0x38, 0x39,  /* STTS751-0 */
+	0x4A, 0x4B, 0x3A, 0x3B,  /* STTS751-1 */
+	I2C_CLIENT_END };
+
+#define STTS751_REG_TEMP_H	0x00
+#define STTS751_REG_STATUS	0x01
+#define STTS751_STATUS_TRIPT	BIT(0)
+#define STTS751_STATUS_TRIPL	BIT(5)
+#define STTS751_STATUS_TRIPH	BIT(6)
+#define STTS751_REG_TEMP_L	0x02
+#define STTS751_REG_CONF	0x03
+#define STTS751_CONF_RES_MASK	0x0C
+#define STTS751_CONF_RES_SHIFT  2
+#define STTS751_CONF_EVENT_DIS  BIT(7)
+#define STTS751_CONF_STOP	BIT(6)
+#define STTS751_REG_RATE	0x04
+#define STTS751_REG_HLIM_H	0x05
+#define STTS751_REG_HLIM_L	0x06
+#define STTS751_REG_LLIM_H	0x07
+#define STTS751_REG_LLIM_L	0x08
+#define STTS751_REG_TLIM	0x20
+#define STTS751_REG_HYST	0x21
+#define STTS751_REG_SMBUS_TO	0x22
+
+#define STTS751_REG_PROD_ID	0xFD
+#define STTS751_REG_MAN_ID	0xFE
+#define STTS751_REG_REV_ID	0xFF
+
+#define STTS751_0_PROD_ID	0x00
+#define STTS751_1_PROD_ID	0x01
+#define ST_MAN_ID		0x53
+
+/*
+ * Possible update intervals are (in mS):
+ * 16000, 8000, 4000, 2000, 1000, 500, 250, 125, 62.5, 31.25
+ * However we are not going to complicate things too much and we stick to the
+ * approx value in mS.
+ */
+static const int stts751_intervals[] = {
+	16000, 8000, 4000, 2000, 1000, 500, 250, 125, 63, 31
+};
+
+static const struct i2c_device_id stts751_id[] = {
+	{ .name = "stts751" },
+	{ }
+};
+
+static const struct of_device_id __maybe_unused stts751_of_match[] = {
+	{ .compatible = "st,stts751" },
+	{ },
+};
+MODULE_DEVICE_TABLE(of, stts751_of_match);
+
+struct stts751_priv {
+	struct device *dev;
+	struct i2c_client *client;
+	struct mutex access_lock;
+	u8 interval;
+	int res;
+	int event_max, event_min;
+	int therm;
+	int hyst;
+	int temp;
+	unsigned long last_update, last_alert_update;
+	u8 config;
+	bool min_alert, max_alert, therm_trip;
+	bool data_valid, alert_valid;
+	bool notify_max, notify_min;
+};
+
+/*
+ * These functions converts temperature from HW format to integer format and
+ * vice-vers. They are (mostly) taken from lm90 driver. Unit is in mC.
+ */
+static int stts751_to_deg(s16 hw_val)
+{
+	return hw_val * 125 / 32;
+}
+
+static s32 stts751_to_hw(int val)
+{
+	return DIV_ROUND_CLOSEST(val, 125) * 32;
+}
+
+static int stts751_adjust_resolution(struct stts751_priv *priv)
+{
+	u8 res;
+
+	switch (priv->interval) {
+	case 9:
+		/* 10 bits */
+		res = 0;
+		break;
+	case 8:
+		/* 11 bits */
+		res = 1;
+		break;
+	default:
+		/* 12 bits */
+		res = 3;
+		break;
+	}
+
+	if (priv->res == res)
+		return 0;
+
+	priv->config &= ~STTS751_CONF_RES_MASK;
+	priv->config |= res << STTS751_CONF_RES_SHIFT;
+	dev_dbg(&priv->client->dev, "setting res %d. config %x",
+		res, priv->config);
+	priv->res = res;
+
+	return i2c_smbus_write_byte_data(priv->client,
+				STTS751_REG_CONF, priv->config);
+}
+
+static int stts751_update_temp(struct stts751_priv *priv)
+{
+	s32 integer1, integer2, frac;
+
+	/*
+	 * There is a trick here, like in the lm90 driver. We have to read two
+	 * registers to get the sensor temperature, but we have to beware a
+	 * conversion could occur between the readings. We could use the
+	 * one-shot conversion register, but we don't want to do this (disables
+	 * hardware monitoring). So the solution used here is to read the high
+	 * byte once, then the low byte, then the high byte again. If the new
+	 * high byte matches the old one, then we have a valid reading. Else we
+	 * have to read the low byte again, and now we believe we have a correct
+	 * reading.
+	 */
+	integer1 = i2c_smbus_read_byte_data(priv->client, STTS751_REG_TEMP_H);
+	if (integer1 < 0) {
+		dev_dbg(&priv->client->dev,
+			"I2C read failed (temp H). ret: %x\n", integer1);
+		return integer1;
+	}
+
+	frac = i2c_smbus_read_byte_data(priv->client, STTS751_REG_TEMP_L);
+	if (frac < 0) {
+		dev_dbg(&priv->client->dev,
+			"I2C read failed (temp L). ret: %x\n", frac);
+		return frac;
+	}
+
+	integer2 = i2c_smbus_read_byte_data(priv->client, STTS751_REG_TEMP_H);
+	if (integer2 < 0) {
+		dev_dbg(&priv->client->dev,
+			"I2C 2nd read failed (temp H). ret: %x\n", integer2);
+		return integer2;
+	}
+
+	if (integer1 != integer2) {
+		frac = i2c_smbus_read_byte_data(priv->client,
+						STTS751_REG_TEMP_L);
+		if (frac < 0) {
+			dev_dbg(&priv->client->dev,
+				"I2C 2nd read failed (temp L). ret: %x\n",
+				frac);
+			return frac;
+		}
+	}
+
+	priv->temp = stts751_to_deg((integer1 << 8) | frac);
+	return 0;
+}
+
+static int stts751_set_temp_reg16(struct stts751_priv *priv, int temp,
+				  u8 hreg, u8 lreg)
+{
+	s32 hwval;
+	int ret;
+
+	hwval = stts751_to_hw(temp);
+
+	ret = i2c_smbus_write_byte_data(priv->client, hreg, hwval >> 8);
+	if (ret)
+		return ret;
+
+	return i2c_smbus_write_byte_data(priv->client, lreg, hwval & 0xff);
+}
+
+static int stts751_set_temp_reg8(struct stts751_priv *priv, int temp, u8 reg)
+{
+	s32 hwval;
+
+	hwval = stts751_to_hw(temp);
+	return i2c_smbus_write_byte_data(priv->client, reg, hwval >> 8);
+}
+
+static int stts751_read_reg16(struct stts751_priv *priv, int *temp,
+			      u8 hreg, u8 lreg)
+{
+	int integer, frac;
+
+	integer = i2c_smbus_read_byte_data(priv->client, hreg);
+	if (integer < 0)
+		return integer;
+
+	frac = i2c_smbus_read_byte_data(priv->client, lreg);
+	if (frac < 0)
+		return frac;
+
+	*temp = stts751_to_deg((integer << 8) | frac);
+
+	return 0;
+}
+
+static int stts751_read_reg8(struct stts751_priv *priv, int *temp, u8 reg)
+{
+	int integer;
+
+	integer = i2c_smbus_read_byte_data(priv->client, reg);
+	if (integer < 0)
+		return integer;
+
+	*temp = stts751_to_deg(integer << 8);
+
+	return 0;
+}
+
+/*
+ * Update alert flags without waiting for cache to expire. We detects alerts
+ * immediately for the sake of the alert handler; we still need to deal with
+ * caching to workaround the fact that alarm flags int the status register,
+ * despite what the datasheet claims, gets always cleared on read.
+ */
+static int stts751_update_alert(struct stts751_priv *priv)
+{
+	int ret;
+	bool conv_done;
+	int cache_time = msecs_to_jiffies(stts751_intervals[priv->interval]);
+
+	/*
+	 * Add another 10% because if we run faster than the HW conversion
+	 * rate we will end up in reporting incorrectly alarms.
+	 */
+	cache_time += cache_time / 10;
+
+	ret = i2c_smbus_read_byte_data(priv->client, STTS751_REG_STATUS);
+	if (ret < 0)
+		return ret;
+
+	dev_dbg(&priv->client->dev, "status reg %x\n", ret);
+	conv_done = ret & (STTS751_STATUS_TRIPH | STTS751_STATUS_TRIPL);
+	/*
+	 * Reset the cache if the cache time expired, or if we are sure
+	 * we have valid data from a device conversion, or if we know
+	 * our cache has been never written.
+	 *
+	 * Note that when the cache has been never written the point is
+	 * to correctly initialize the timestamp, rather than clearing
+	 * the cache values.
+	 *
+	 * Note that updating the cache timestamp when we get an alarm flag
+	 * is required, otherwise we could incorrectly report alarms to be zero.
+	 */
+	if (time_after(jiffies,	priv->last_alert_update + cache_time) ||
+	    conv_done || !priv->alert_valid) {
+		priv->max_alert = false;
+		priv->min_alert = false;
+		priv->alert_valid = true;
+		priv->last_alert_update = jiffies;
+		dev_dbg(&priv->client->dev, "invalidating alert cache\n");
+	}
+
+	priv->max_alert |= !!(ret & STTS751_STATUS_TRIPH);
+	priv->min_alert |= !!(ret & STTS751_STATUS_TRIPL);
+	priv->therm_trip = !!(ret & STTS751_STATUS_TRIPT);
+
+	dev_dbg(&priv->client->dev, "max_alert: %d, min_alert: %d, therm_trip: %d\n",
+		priv->max_alert, priv->min_alert, priv->therm_trip);
+
+	return 0;
+}
+
+static void stts751_alert(struct i2c_client *client,
+			  enum i2c_alert_protocol type, unsigned int data)
+{
+	int ret;
+	struct stts751_priv *priv = i2c_get_clientdata(client);
+
+	if (type != I2C_PROTOCOL_SMBUS_ALERT)
+		return;
+
+	dev_dbg(&client->dev, "alert!");
+
+	mutex_lock(&priv->access_lock);
+	ret = stts751_update_alert(priv);
+	if (ret < 0) {
+		/* default to worst case */
+		priv->max_alert = true;
+		priv->min_alert = true;
+
+		dev_warn(priv->dev,
+			 "Alert received, but can't communicate to the device. Triggering all alarms!");
+	}
+
+	if (priv->max_alert) {
+		if (priv->notify_max)
+			dev_notice(priv->dev, "got alert for HIGH temperature");
+		priv->notify_max = false;
+
+		/* unblock alert poll */
+		sysfs_notify(&priv->dev->kobj, NULL, "temp1_max_alarm");
+	}
+
+	if (priv->min_alert) {
+		if (priv->notify_min)
+			dev_notice(priv->dev, "got alert for LOW temperature");
+		priv->notify_min = false;
+
+		/* unblock alert poll */
+		sysfs_notify(&priv->dev->kobj, NULL, "temp1_min_alarm");
+	}
+
+	if (priv->min_alert || priv->max_alert)
+		kobject_uevent(&priv->dev->kobj, KOBJ_CHANGE);
+
+	mutex_unlock(&priv->access_lock);
+}
+
+static int stts751_update(struct stts751_priv *priv)
+{
+	int ret;
+	int cache_time = msecs_to_jiffies(stts751_intervals[priv->interval]);
+
+	if (time_after(jiffies,	priv->last_update + cache_time) ||
+	    !priv->data_valid) {
+		ret = stts751_update_temp(priv);
+		if (ret)
+			return ret;
+
+		ret = stts751_update_alert(priv);
+		if (ret)
+			return ret;
+		priv->data_valid = true;
+		priv->last_update = jiffies;
+	}
+
+	return 0;
+}
+
+static ssize_t max_alarm_show(struct device *dev,
+			      struct device_attribute *attr, char *buf)
+{
+	int ret;
+	struct stts751_priv *priv = dev_get_drvdata(dev);
+
+	mutex_lock(&priv->access_lock);
+	ret = stts751_update(priv);
+	if (!ret)
+		priv->notify_max = true;
+	mutex_unlock(&priv->access_lock);
+	if (ret < 0)
+		return ret;
+
+	return sysfs_emit(buf, "%d\n", priv->max_alert);
+}
+
+static ssize_t min_alarm_show(struct device *dev,
+			      struct device_attribute *attr, char *buf)
+{
+	int ret;
+	struct stts751_priv *priv = dev_get_drvdata(dev);
+
+	mutex_lock(&priv->access_lock);
+	ret = stts751_update(priv);
+	if (!ret)
+		priv->notify_min = true;
+	mutex_unlock(&priv->access_lock);
+	if (ret < 0)
+		return ret;
+
+	return sysfs_emit(buf, "%d\n", priv->min_alert);
+}
+
+static ssize_t input_show(struct device *dev, struct device_attribute *attr,
+			  char *buf)
+{
+	int ret;
+	struct stts751_priv *priv = dev_get_drvdata(dev);
+
+	mutex_lock(&priv->access_lock);
+	ret = stts751_update(priv);
+	mutex_unlock(&priv->access_lock);
+	if (ret < 0)
+		return ret;
+
+	return sysfs_emit(buf, "%d\n", priv->temp);
+}
+
+static ssize_t therm_show(struct device *dev, struct device_attribute *attr,
+			  char *buf)
+{
+	struct stts751_priv *priv = dev_get_drvdata(dev);
+
+	return sysfs_emit(buf, "%d\n", priv->therm);
+}
+
+static ssize_t therm_store(struct device *dev, struct device_attribute *attr,
+			   const char *buf, size_t count)
+{
+	int ret;
+	long temp;
+	struct stts751_priv *priv = dev_get_drvdata(dev);
+
+	if (kstrtol(buf, 10, &temp) < 0)
+		return -EINVAL;
+
+	/* HW works in range -64C to +127.937C */
+	temp = clamp_val(temp, -64000, 127937);
+	mutex_lock(&priv->access_lock);
+	ret = stts751_set_temp_reg8(priv, temp, STTS751_REG_TLIM);
+	if (ret)
+		goto exit;
+
+	dev_dbg(&priv->client->dev, "setting therm %ld", temp);
+
+	/*
+	 * hysteresis reg is relative to therm, so the HW does not need to be
+	 * adjusted, we need to update our local copy only.
+	 */
+	priv->hyst = temp - (priv->therm - priv->hyst);
+	priv->therm = temp;
+
+exit:
+	mutex_unlock(&priv->access_lock);
+	if (ret)
+		return ret;
+
+	return count;
+}
+
+static ssize_t hyst_show(struct device *dev, struct device_attribute *attr,
+			 char *buf)
+{
+	struct stts751_priv *priv = dev_get_drvdata(dev);
+
+	return sysfs_emit(buf, "%d\n", priv->hyst);
+}
+
+static ssize_t hyst_store(struct device *dev, struct device_attribute *attr,
+			  const char *buf, size_t count)
+{
+	int ret;
+	long temp;
+
+	struct stts751_priv *priv = dev_get_drvdata(dev);
+
+	if (kstrtol(buf, 10, &temp) < 0)
+		return -EINVAL;
+
+	mutex_lock(&priv->access_lock);
+	/* HW works in range -64C to +127.937C */
+	temp = clamp_val(temp, -64000, priv->therm);
+	priv->hyst = temp;
+	dev_dbg(&priv->client->dev, "setting hyst %ld", temp);
+	temp = priv->therm - temp;
+	ret = stts751_set_temp_reg8(priv, temp, STTS751_REG_HYST);
+	mutex_unlock(&priv->access_lock);
+	if (ret)
+		return ret;
+
+	return count;
+}
+
+static ssize_t therm_trip_show(struct device *dev,
+			       struct device_attribute *attr, char *buf)
+{
+	int ret;
+	struct stts751_priv *priv = dev_get_drvdata(dev);
+
+	mutex_lock(&priv->access_lock);
+	ret = stts751_update(priv);
+	mutex_unlock(&priv->access_lock);
+	if (ret < 0)
+		return ret;
+
+	return sysfs_emit(buf, "%d\n", priv->therm_trip);
+}
+
+static ssize_t max_show(struct device *dev, struct device_attribute *attr,
+			char *buf)
+{
+	struct stts751_priv *priv = dev_get_drvdata(dev);
+
+	return sysfs_emit(buf, "%d\n", priv->event_max);
+}
+
+static ssize_t max_store(struct device *dev, struct device_attribute *attr,
+			 const char *buf, size_t count)
+{
+	int ret;
+	long temp;
+	struct stts751_priv *priv = dev_get_drvdata(dev);
+
+	if (kstrtol(buf, 10, &temp) < 0)
+		return -EINVAL;
+
+	mutex_lock(&priv->access_lock);
+	/* HW works in range -64C to +127.937C */
+	temp = clamp_val(temp, priv->event_min, 127937);
+	ret = stts751_set_temp_reg16(priv, temp,
+				     STTS751_REG_HLIM_H, STTS751_REG_HLIM_L);
+	if (ret)
+		goto exit;
+
+	dev_dbg(&priv->client->dev, "setting event max %ld", temp);
+	priv->event_max = temp;
+	ret = count;
+exit:
+	mutex_unlock(&priv->access_lock);
+	return ret;
+}
+
+static ssize_t min_show(struct device *dev, struct device_attribute *attr,
+			char *buf)
+{
+	struct stts751_priv *priv = dev_get_drvdata(dev);
+
+	return sysfs_emit(buf, "%d\n", priv->event_min);
+}
+
+static ssize_t min_store(struct device *dev, struct device_attribute *attr,
+			 const char *buf, size_t count)
+{
+	int ret;
+	long temp;
+	struct stts751_priv *priv = dev_get_drvdata(dev);
+
+	if (kstrtol(buf, 10, &temp) < 0)
+		return -EINVAL;
+
+	mutex_lock(&priv->access_lock);
+	/* HW works in range -64C to +127.937C */
+	temp = clamp_val(temp, -64000, priv->event_max);
+	ret = stts751_set_temp_reg16(priv, temp,
+				     STTS751_REG_LLIM_H, STTS751_REG_LLIM_L);
+	if (ret)
+		goto exit;
+
+	dev_dbg(&priv->client->dev, "setting event min %ld", temp);
+	priv->event_min = temp;
+	ret = count;
+exit:
+	mutex_unlock(&priv->access_lock);
+	return ret;
+}
+
+static ssize_t interval_show(struct device *dev,
+			     struct device_attribute *attr, char *buf)
+{
+	struct stts751_priv *priv = dev_get_drvdata(dev);
+
+	return sysfs_emit(buf, "%d\n",
+			  stts751_intervals[priv->interval]);
+}
+
+static ssize_t interval_store(struct device *dev,
+			      struct device_attribute *attr, const char *buf,
+			      size_t count)
+{
+	unsigned long val;
+	int idx;
+	int ret = count;
+	struct stts751_priv *priv = dev_get_drvdata(dev);
+
+	if (kstrtoul(buf, 10, &val) < 0)
+		return -EINVAL;
+
+	idx = find_closest_descending(val, stts751_intervals,
+				      ARRAY_SIZE(stts751_intervals));
+
+	dev_dbg(&priv->client->dev, "setting interval. req:%lu, idx: %d, val: %d",
+		val, idx, stts751_intervals[idx]);
+
+	mutex_lock(&priv->access_lock);
+	if (priv->interval == idx)
+		goto exit;
+
+	/*
+	 * In early development stages I've become suspicious about the chip
+	 * starting to misbehave if I ever set, even briefly, an invalid
+	 * configuration. While I'm not sure this is really needed, be
+	 * conservative and set rate/resolution in such an order that avoids
+	 * passing through an invalid configuration.
+	 */
+
+	/* speed up: lower the resolution, then modify convrate */
+	if (priv->interval < idx) {
+		dev_dbg(&priv->client->dev, "lower resolution, then modify convrate");
+		priv->interval = idx;
+		ret = stts751_adjust_resolution(priv);
+		if (ret)
+			goto exit;
+	}
+
+	ret = i2c_smbus_write_byte_data(priv->client, STTS751_REG_RATE, idx);
+	if (ret)
+		goto exit;
+	/* slow down: modify convrate, then raise resolution */
+	if (priv->interval != idx) {
+		dev_dbg(&priv->client->dev, "modify convrate, then raise resolution");
+		priv->interval = idx;
+		ret = stts751_adjust_resolution(priv);
+		if (ret)
+			goto exit;
+	}
+	ret = count;
+exit:
+	mutex_unlock(&priv->access_lock);
+
+	return ret;
+}
+
+static int stts751_detect(struct i2c_client *new_client,
+			  struct i2c_board_info *info)
+{
+	struct i2c_adapter *adapter = new_client->adapter;
+	const char *name;
+	int tmp;
+
+	if (!i2c_check_functionality(adapter, I2C_FUNC_SMBUS_BYTE_DATA))
+		return -ENODEV;
+
+	tmp = i2c_smbus_read_byte_data(new_client, STTS751_REG_MAN_ID);
+	if (tmp != ST_MAN_ID)
+		return -ENODEV;
+
+	/* lower temperaure registers always have bits 0-3 set to zero */
+	tmp = i2c_smbus_read_byte_data(new_client, STTS751_REG_TEMP_L);
+	if (tmp & 0xf)
+		return -ENODEV;
+
+	tmp = i2c_smbus_read_byte_data(new_client, STTS751_REG_HLIM_L);
+	if (tmp & 0xf)
+		return -ENODEV;
+
+	tmp = i2c_smbus_read_byte_data(new_client, STTS751_REG_LLIM_L);
+	if (tmp & 0xf)
+		return -ENODEV;
+
+	/* smbus timeout register always have bits 0-7 set to zero */
+	tmp = i2c_smbus_read_byte_data(new_client, STTS751_REG_SMBUS_TO);
+	if (tmp & 0x7f)
+		return -ENODEV;
+
+	tmp = i2c_smbus_read_byte_data(new_client, STTS751_REG_PROD_ID);
+
+	switch (tmp) {
+	case STTS751_0_PROD_ID:
+		name = "STTS751-0";
+		break;
+	case STTS751_1_PROD_ID:
+		name = "STTS751-1";
+		break;
+	default:
+		return -ENODEV;
+	}
+	dev_dbg(&new_client->dev, "Chip %s detected", name);
+
+	strscpy(info->type, stts751_id[0].name, I2C_NAME_SIZE);
+	return 0;
+}
+
+static int stts751_read_chip_config(struct stts751_priv *priv)
+{
+	int ret;
+	int tmp;
+
+	ret = i2c_smbus_read_byte_data(priv->client, STTS751_REG_CONF);
+	if (ret < 0)
+		return ret;
+	priv->config = ret;
+	priv->res = (ret & STTS751_CONF_RES_MASK) >> STTS751_CONF_RES_SHIFT;
+
+	ret = i2c_smbus_read_byte_data(priv->client, STTS751_REG_RATE);
+	if (ret < 0)
+		return ret;
+	if (ret >= ARRAY_SIZE(stts751_intervals)) {
+		dev_err(priv->dev, "Unrecognized conversion rate 0x%x\n", ret);
+		return -ENODEV;
+	}
+	priv->interval = ret;
+
+	ret = stts751_read_reg16(priv, &priv->event_max,
+				 STTS751_REG_HLIM_H, STTS751_REG_HLIM_L);
+	if (ret)
+		return ret;
+
+	ret = stts751_read_reg16(priv, &priv->event_min,
+				 STTS751_REG_LLIM_H, STTS751_REG_LLIM_L);
+	if (ret)
+		return ret;
+
+	ret = stts751_read_reg8(priv, &priv->therm, STTS751_REG_TLIM);
+	if (ret)
+		return ret;
+
+	ret = stts751_read_reg8(priv, &tmp, STTS751_REG_HYST);
+	if (ret)
+		return ret;
+	priv->hyst = priv->therm - tmp;
+
+	return 0;
+}
+
+static SENSOR_DEVICE_ATTR_RO(temp1_input, input, 0);
+static SENSOR_DEVICE_ATTR_RW(temp1_min, min, 0);
+static SENSOR_DEVICE_ATTR_RW(temp1_max, max, 0);
+static SENSOR_DEVICE_ATTR_RO(temp1_min_alarm, min_alarm, 0);
+static SENSOR_DEVICE_ATTR_RO(temp1_max_alarm, max_alarm, 0);
+static SENSOR_DEVICE_ATTR_RW(temp1_crit, therm, 0);
+static SENSOR_DEVICE_ATTR_RW(temp1_crit_hyst, hyst, 0);
+static SENSOR_DEVICE_ATTR_RO(temp1_crit_alarm, therm_trip, 0);
+static SENSOR_DEVICE_ATTR_RW(update_interval, interval, 0);
+
+static struct attribute *stts751_attrs[] = {
+	&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_min_alarm.dev_attr.attr,
+	&sensor_dev_attr_temp1_max_alarm.dev_attr.attr,
+	&sensor_dev_attr_temp1_crit.dev_attr.attr,
+	&sensor_dev_attr_temp1_crit_hyst.dev_attr.attr,
+	&sensor_dev_attr_temp1_crit_alarm.dev_attr.attr,
+	&sensor_dev_attr_update_interval.dev_attr.attr,
+	NULL
+};
+ATTRIBUTE_GROUPS(stts751);
+
+static int stts751_probe(struct i2c_client *client)
+{
+	struct stts751_priv *priv;
+	int ret;
+	bool smbus_nto;
+	int rev_id;
+
+	priv = devm_kzalloc(&client->dev, sizeof(*priv), GFP_KERNEL);
+	if (!priv)
+		return -ENOMEM;
+
+	priv->client = client;
+	priv->notify_max = true;
+	priv->notify_min = true;
+	i2c_set_clientdata(client, priv);
+	mutex_init(&priv->access_lock);
+
+	if (device_property_present(&client->dev,
+				    "smbus-timeout-disable")) {
+		smbus_nto = device_property_read_bool(&client->dev,
+						      "smbus-timeout-disable");
+
+		ret = i2c_smbus_write_byte_data(client,	STTS751_REG_SMBUS_TO,
+						smbus_nto ? 0 : 0x80);
+		if (ret)
+			return ret;
+	}
+
+	rev_id = i2c_smbus_read_byte_data(client, STTS751_REG_REV_ID);
+	if (rev_id < 0)
+		return -ENODEV;
+	if (rev_id != 0x1) {
+		dev_dbg(&client->dev, "Chip revision 0x%x is untested\n",
+			rev_id);
+	}
+
+	ret = stts751_read_chip_config(priv);
+	if (ret)
+		return ret;
+
+	priv->config &= ~(STTS751_CONF_STOP | STTS751_CONF_EVENT_DIS);
+	ret = i2c_smbus_write_byte_data(client,	STTS751_REG_CONF, priv->config);
+	if (ret)
+		return ret;
+
+	priv->dev = devm_hwmon_device_register_with_groups(&client->dev,
+							client->name, priv,
+							stts751_groups);
+	return PTR_ERR_OR_ZERO(priv->dev);
+}
+
+MODULE_DEVICE_TABLE(i2c, stts751_id);
+
+static struct i2c_driver stts751_driver = {
+	.class		= I2C_CLASS_HWMON,
+	.driver = {
+		.name	= DEVNAME,
+		.of_match_table = of_match_ptr(stts751_of_match),
+	},
+	.probe		= stts751_probe,
+	.id_table	= stts751_id,
+	.detect		= stts751_detect,
+	.alert		= stts751_alert,
+	.address_list	= normal_i2c,
+};
+
+module_i2c_driver(stts751_driver);
+
+MODULE_AUTHOR("Andrea Merello <andrea.merello@gmail.com>");
+MODULE_DESCRIPTION("STTS751 sensor driver");
+MODULE_LICENSE("GPL");