[PATCH v11 2/2] hwmon: (asus_wmi_sensors) Support X370 Asus WMI.

[Denis Pauk <pauk.denis@gmail.com>]

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Provides a Linux kernel module "asus_wmi_sensors" that provides sensor
readouts via ASUS' WMI interface present in the UEFI of
X370/X470/B450/X399 Ryzen motherboards.

Supported motherboards:
* ROG CROSSHAIR VI HERO,
* PRIME X399-A,
* PRIME X470-PRO,
* ROG CROSSHAIR VI EXTREME,
* ROG CROSSHAIR VI HERO (WI-FI AC),
* ROG CROSSHAIR VII HERO,
* ROG CROSSHAIR VII HERO (WI-FI),
* ROG STRIX Z390-F GAMING,
* ROG STRIX B450-E GAMING,
* ROG STRIX B450-F GAMING,
* ROG STRIX B450-I GAMING,
* ROG STRIX X399-E GAMING,
* ROG STRIX X470-F GAMING,
* ROG STRIX X470-I GAMING,
* ROG ZENITH EXTREME,
* ROG ZENITH EXTREME ALPHA.

Signed-off-by: Denis Pauk <pauk.denis@gmail.com>
Co-developed-by: Ed Brindley <kernel@maidavale.org>
Signed-off-by: Ed Brindley <kernel@maidavale.org>

---
Changes in v11:
- Add "ROG STRIX Z390-F GAMING" to list of supported boards.

Changes in v10:
- Use long for sensor values.
- Remove unrequired linux/hwmon-sysfs.h
- Change code style in error status return.
- Remove unuses wmi.buffer and fix type of source.

Changes in v9:
- Fix memory leaks in asus_wmi_*().

Changes in v8:
- Fix codestyle in defines and comments.
- Call mutex_lock inside of functions.

Changes in v7:
- Add depends on ACPI_WMI to Kconfig.
- Clean up defines names.

Changes in v6:
- Add asus_wmi_sensor to documentation index.

Changes in v5:
- Fixes build issue reported by kernel test robot with disabled ACPI_WMI.
- Remove sensor->name check as always eevaluated to true.

Changes in v4:
- Implement wmi driver instead platform driver.
- Update documentation.

Changes in v3:
- Use MODULE_DEVICE_TABLE for match devices.
- Add documentaion for driver.

Changes in v2:
- Add module for boards with support of WMI interface returned sensor name and
  value of sensor..
---
 Documentation/hwmon/asus_wmi_sensors.rst |  77 +++
 Documentation/hwmon/index.rst            |   1 +
 MAINTAINERS                              |   1 +
 drivers/hwmon/Kconfig                    |  12 +
 drivers/hwmon/Makefile                   |   1 +
 drivers/hwmon/asus_wmi_sensors.c         | 665 +++++++++++++++++++++++
 6 files changed, 757 insertions(+)
 create mode 100644 Documentation/hwmon/asus_wmi_sensors.rst
 create mode 100644 drivers/hwmon/asus_wmi_sensors.c

diff --git a/Documentation/hwmon/asus_wmi_sensors.rst b/Documentation/hwmon/asus_wmi_sensors.rst
new file mode 100644
index 000000000000..a534a8a83343
--- /dev/null
+++ b/Documentation/hwmon/asus_wmi_sensors.rst
@@ -0,0 +1,77 @@
+.. SPDX-License-Identifier: GPL-2.0-or-later
+
+Kernel driver asus_wmi_sensors
+=================================
+
+Supported boards:
+ * PRIME X399-A,
+ * PRIME X470-PRO,
+ * ROG CROSSHAIR VI EXTREME,
+ * ROG CROSSHAIR VI HERO,
+ * ROG CROSSHAIR VI HERO (WI-FI AC),
+ * ROG CROSSHAIR VII HERO,
+ * ROG CROSSHAIR VII HERO (WI-FI),
+ * ROG STRIX Z390-F GAMING,
+ * ROG STRIX B450-E GAMING,
+ * ROG STRIX B450-F GAMING,
+ * ROG STRIX B450-I GAMING,
+ * ROG STRIX X399-E GAMING,
+ * ROG STRIX X470-F GAMING,
+ * ROG STRIX X470-I GAMING,
+ * ROG ZENITH EXTREME,
+ * ROG ZENITH EXTREME ALPHA.
+
+Authors:
+    - Ed Brindley <kernel@maidavale.org>
+
+Description:
+------------
+ASUS mainboards publish hardware monitoring information via WMI interface.
+
+ASUS WMI interface provides a methods to get list of sensors and values of
+such, which is utilized by this driver to publish those sensor readings to the
+HWMON system. The driver is aware of and reads the following sensors:
+ * CPU Core Voltage,
+ * CPU SOC Voltage,
+ * DRAM Voltage,
+ * VDDP Voltage,
+ * 1.8V PLL Voltage,
+ * +12V Voltage,
+ * +5V Voltage,
+ * 3VSB Voltage,
+ * VBAT Voltage,
+ * AVCC3 Voltage,
+ * SB 1.05V Voltage,
+ * CPU Core Voltage,
+ * CPU SOC Voltage,
+ * DRAM Voltage,
+ * CPU Fan RPM,
+ * Chassis Fan 1 RPM,
+ * Chassis Fan 2 RPM,
+ * Chassis Fan 3 RPM,
+ * HAMP Fan RPM,
+ * Water Pump RPM,
+ * CPU OPT RPM,
+ * Water Flow RPM,
+ * AIO Pump RPM,
+ * CPU Temperature,
+ * CPU Socket Temperature,
+ * Motherboard Temperature,
+ * Chipset Temperature,
+ * Tsensor 1 Temperature,
+ * CPU VRM Temperature,
+ * Water In,
+ * Water Out,
+ * CPU VRM Output Current.
+
+Known Issues:
+* The WMI implementation in some of Asus' BIOSes is buggy. This can result in
+   fans stopping, fans getting stuck at max speed, or temperature readouts
+   getting stuck. This is not an issue with the driver, but the BIOS. The Prime
+   X470 Pro seems particularly bad for this. The more frequently the WMI
+   interface is polled the greater the potential for this to happen. Until you
+   have subjected your computer to an extended soak test while polling the
+   sensors frequently, don't leave you computer unattended. Upgrading to new
+   BIOS version with method version greater than or equal to two should
+   rectify the issue.
+* A few boards report 12v voltages to be ~10v.
diff --git a/Documentation/hwmon/index.rst b/Documentation/hwmon/index.rst
index 3e196eaff360..9c9361d76f3d 100644
--- a/Documentation/hwmon/index.rst
+++ b/Documentation/hwmon/index.rst
@@ -44,6 +44,7 @@ Hardware Monitoring Kernel Drivers
    asc7621
    aspeed-pwm-tacho
    asus_wmi_ec_sensors
+   asus_wmi_sensors
    bcm54140
    bel-pfe
    bpa-rs600
diff --git a/MAINTAINERS b/MAINTAINERS
index 7a3812b8bbec..2b43f1b0e140 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -2994,6 +2994,7 @@ M:	Denis Pauk <pauk.denis@gmail.com>
 L:	linux-hwmon@vger.kernel.org
 S:	Maintained
 F:	drivers/hwmon/asus_wmi_ec_sensors.c
+F:	drivers/hwmon/asus_wmi_sensors.c
 
 ASUS WIRELESS RADIO CONTROL DRIVER
 M:	João Paulo Rechi Vita <jprvita@gmail.com>
diff --git a/drivers/hwmon/Kconfig b/drivers/hwmon/Kconfig
index 81f5e2ddbdf5..44886bf23aed 100644
--- a/drivers/hwmon/Kconfig
+++ b/drivers/hwmon/Kconfig
@@ -2228,6 +2228,18 @@ config SENSORS_ATK0110
 	  This driver can also be built as a module. If so, the module
 	  will be called asus_atk0110.
 
+config SENSORS_ASUS_WMI
+	tristate "ASUS WMI X370/X470/B450/X399"
+	depends on ACPI_WMI
+	help
+	  If you say yes here you get support for the ACPI hardware monitoring
+	  interface found in X370/X470/B450/X399 ASUS motherboards. This driver
+	  will provide readings of fans, voltages and temperatures through the system
+	  firmware.
+
+	  This driver can also be built as a module. If so, the module
+	  will be called asus_wmi_sensors.
+
 config SENSORS_ASUS_WMI_EC
 	tristate "ASUS WMI B550/X570"
 	depends on ACPI_WMI
diff --git a/drivers/hwmon/Makefile b/drivers/hwmon/Makefile
index 821345e49107..3a1551b3d570 100644
--- a/drivers/hwmon/Makefile
+++ b/drivers/hwmon/Makefile
@@ -9,6 +9,7 @@ obj-$(CONFIG_HWMON_VID)		+= hwmon-vid.o
 # APCI drivers
 obj-$(CONFIG_SENSORS_ACPI_POWER) += acpi_power_meter.o
 obj-$(CONFIG_SENSORS_ATK0110)	+= asus_atk0110.o
+obj-$(CONFIG_SENSORS_ASUS_WMI)	+= asus_wmi_sensors.o
 obj-$(CONFIG_SENSORS_ASUS_WMI_EC)	+= asus_wmi_ec_sensors.o
 
 # Native drivers
diff --git a/drivers/hwmon/asus_wmi_sensors.c b/drivers/hwmon/asus_wmi_sensors.c
new file mode 100644
index 000000000000..4ff5cd64ff4b
--- /dev/null
+++ b/drivers/hwmon/asus_wmi_sensors.c
@@ -0,0 +1,665 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * HWMON driver for ASUS motherboards that provides sensor readouts via WMI
+ * interface present in the UEFI of the X370/X470/B450/X399 Ryzen motherboards.
+ *
+ * Copyright (C) 2018-2019 Ed Brindley <kernel@maidavale.org>
+ *
+ * WMI interface provides:
+ * - CPU Core Voltage,
+ * - CPU SOC Voltage,
+ * - DRAM Voltage,
+ * - VDDP Voltage,
+ * - 1.8V PLL Voltage,
+ * - +12V Voltage,
+ * - +5V Voltage,
+ * - 3VSB Voltage,
+ * - VBAT Voltage,
+ * - AVCC3 Voltage,
+ * - SB 1.05V Voltage,
+ * - CPU Core Voltage,
+ * - CPU SOC Voltage,
+ * - DRAM Voltage,
+ * - CPU Fan RPM,
+ * - Chassis Fan 1 RPM,
+ * - Chassis Fan 2 RPM,
+ * - Chassis Fan 3 RPM,
+ * - HAMP Fan RPM,
+ * - Water Pump RPM,
+ * - CPU OPT RPM,
+ * - Water Flow RPM,
+ * - AIO Pump RPM,
+ * - CPU Temperature,
+ * - CPU Socket Temperature,
+ * - Motherboard Temperature,
+ * - Chipset Temperature,
+ * - Tsensor 1 Temperature,
+ * - CPU VRM Temperature,
+ * - Water In,
+ * - Water Out,
+ * - CPU VRM Output Current.
+ */
+
+#include <linux/acpi.h>
+#include <linux/dmi.h>
+#include <linux/hwmon.h>
+#include <linux/init.h>
+#include <linux/jiffies.h>
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/mutex.h>
+#include <linux/units.h>
+#include <linux/wmi.h>
+
+#define ASUSWMI_MONITORING_GUID		"466747A0-70EC-11DE-8A39-0800200C9A66"
+#define ASUSWMI_METHODID_GET_VALUE	0x52574543 /* RWEC */
+#define ASUSWMI_METHODID_UPDATE_BUFFER	0x51574543 /* QWEC */
+#define ASUSWMI_METHODID_GET_INFO	0x50574543 /* PWEC */
+#define ASUSWMI_METHODID_GET_NUMBER	0x50574572 /* PWEr */
+#define ASUSWMI_METHODID_GET_VERSION	0x50574574 /* PWEt */
+
+#define ASUS_WMI_MAX_STR_SIZE		32
+
+#define DMI_EXACT_MATCH_ASUS_BOARD_NAME(name) {					\
+	.matches = {								\
+		DMI_EXACT_MATCH(DMI_BOARD_VENDOR, "ASUSTeK COMPUTER INC."),	\
+		DMI_EXACT_MATCH(DMI_BOARD_NAME, name),				\
+	},									\
+}
+
+static const struct dmi_system_id asus_wmi_dmi_table[] = {
+	DMI_EXACT_MATCH_ASUS_BOARD_NAME("PRIME X399-A"),
+	DMI_EXACT_MATCH_ASUS_BOARD_NAME("PRIME X470-PRO"),
+	DMI_EXACT_MATCH_ASUS_BOARD_NAME("ROG CROSSHAIR VI EXTREME"),
+	DMI_EXACT_MATCH_ASUS_BOARD_NAME("ROG CROSSHAIR VI HERO"),
+	DMI_EXACT_MATCH_ASUS_BOARD_NAME("ROG CROSSHAIR VI HERO (WI-FI AC)"),
+	DMI_EXACT_MATCH_ASUS_BOARD_NAME("ROG CROSSHAIR VII HERO"),
+	DMI_EXACT_MATCH_ASUS_BOARD_NAME("ROG CROSSHAIR VII HERO (WI-FI)"),
+	DMI_EXACT_MATCH_ASUS_BOARD_NAME("ROG STRIX B450-E GAMING"),
+	DMI_EXACT_MATCH_ASUS_BOARD_NAME("ROG STRIX B450-F GAMING"),
+	DMI_EXACT_MATCH_ASUS_BOARD_NAME("ROG STRIX B450-I GAMING"),
+	DMI_EXACT_MATCH_ASUS_BOARD_NAME("ROG STRIX X399-E GAMING"),
+	DMI_EXACT_MATCH_ASUS_BOARD_NAME("ROG STRIX X470-F GAMING"),
+	DMI_EXACT_MATCH_ASUS_BOARD_NAME("ROG STRIX X470-I GAMING"),
+	DMI_EXACT_MATCH_ASUS_BOARD_NAME("ROG STRIX Z390-F GAMING"),
+	DMI_EXACT_MATCH_ASUS_BOARD_NAME("ROG ZENITH EXTREME"),
+	DMI_EXACT_MATCH_ASUS_BOARD_NAME("ROG ZENITH EXTREME ALPHA"),
+	{}
+};
+MODULE_DEVICE_TABLE(dmi, asus_wmi_dmi_table);
+
+enum asus_wmi_sensor_class {
+	VOLTAGE		= 0x0,
+	TEMPERATURE_C	= 0x1,
+	FAN_RPM		= 0x2,
+	CURRENT		= 0x3,
+	WATER_FLOW	= 0x4,
+};
+
+enum asus_wmi_location {
+	CPU		= 0x0,
+	CPU_SOC		= 0x1,
+	DRAM		= 0x2,
+	MOTHERBOARD	= 0x3,
+	CHIPSET		= 0x4,
+	AUX		= 0x5,
+	VRM		= 0x6,
+	COOLER		= 0x7
+};
+
+enum asus_wmi_type {
+	SIGNED_INT	= 0x0,
+	UNSIGNED_INT	= 0x1,
+	SCALED		= 0x3,
+};
+
+enum asus_wmi_source {
+	SIO		= 0x1,
+	EC		= 0x2
+};
+
+static enum hwmon_sensor_types asus_data_types[] = {
+	[VOLTAGE]	= hwmon_in,
+	[TEMPERATURE_C]	= hwmon_temp,
+	[FAN_RPM]	= hwmon_fan,
+	[CURRENT]	= hwmon_curr,
+	[WATER_FLOW]	= hwmon_fan,
+};
+
+static u32 hwmon_attributes[] = {
+	[hwmon_chip]	= HWMON_C_REGISTER_TZ,
+	[hwmon_temp]	= HWMON_T_INPUT | HWMON_T_LABEL,
+	[hwmon_in]	= HWMON_I_INPUT | HWMON_I_LABEL,
+	[hwmon_curr]	= HWMON_C_INPUT | HWMON_C_LABEL,
+	[hwmon_fan]	= HWMON_F_INPUT | HWMON_F_LABEL,
+};
+
+/**
+ * struct asus_wmi_sensor_info - sensor info.
+ * @id: sensor id.
+ * @data_type: sensor class e.g. voltage, temp etc.
+ * @location: sensor location.
+ * @name: sensor name.
+ * @source: sensor source.
+ * @type: sensor type signed, unsigned etc.
+ * @cached_value: cached sensor value.
+ */
+struct asus_wmi_sensor_info {
+	u32 id;
+	int data_type;
+	int location;
+	char name[ASUS_WMI_MAX_STR_SIZE];
+	int source;
+	int type;
+	long cached_value;
+};
+
+struct asus_wmi_wmi_info {
+	unsigned long source_last_updated[3];	/* in jiffies */
+	int sensor_count;
+
+	const struct asus_wmi_sensor_info **info[hwmon_max];
+	struct asus_wmi_sensor_info **info_by_id;
+};
+
+struct asus_wmi_sensors {
+	struct asus_wmi_wmi_info wmi;
+	/* lock access to internal cache */
+	struct mutex lock;
+};
+
+/*
+ * Universal method for calling WMI method
+ */
+static int asus_wmi_call_method(u32 method_id, u32 *args, struct acpi_buffer *output)
+{
+	struct acpi_buffer input = {(acpi_size) sizeof(*args), args };
+	acpi_status status;
+
+	status = wmi_evaluate_method(ASUSWMI_MONITORING_GUID, 0,
+				     method_id, &input, output);
+	if (ACPI_FAILURE(status))
+		return -EIO;
+
+	return 0;
+}
+
+/*
+ * Gets the version of the ASUS sensors interface implemented
+ */
+static int asus_wmi_get_version(u32 *version)
+{
+	struct acpi_buffer output = { ACPI_ALLOCATE_BUFFER, NULL };
+	u32 args[] = {0, 0, 0};
+	union acpi_object *obj;
+	int err;
+
+	err = asus_wmi_call_method(ASUSWMI_METHODID_GET_VERSION, args, &output);
+	if (err)
+		return err;
+
+	obj = output.pointer;
+	if (!obj)
+		return -EIO;
+
+	if (obj->type != ACPI_TYPE_INTEGER) {
+		err = -EIO;
+		goto out_free_obj;
+	}
+
+	err = 0;
+	*version = obj->integer.value;
+
+out_free_obj:
+	ACPI_FREE(obj);
+	return err;
+}
+
+/*
+ * Gets the number of sensor items
+ */
+static int asus_wmi_get_item_count(u32 *count)
+{
+	struct acpi_buffer output = { ACPI_ALLOCATE_BUFFER, NULL };
+	u32 args[] = {0, 0, 0};
+	union acpi_object *obj;
+	int err;
+
+	err = asus_wmi_call_method(ASUSWMI_METHODID_GET_NUMBER, args, &output);
+	if (err)
+		return err;
+
+	obj = output.pointer;
+	if (!obj)
+		return -EIO;
+
+	if (obj->type != ACPI_TYPE_INTEGER) {
+		err = -EIO;
+		goto out_free_obj;
+	}
+
+	err = 0;
+	*count = obj->integer.value;
+
+out_free_obj:
+	ACPI_FREE(obj);
+	return err;
+}
+
+static int asus_wmi_hwmon_add_chan_info(struct hwmon_channel_info *asus_wmi_hwmon_chan,
+					struct device *dev, int num,
+					enum hwmon_sensor_types type, u32 config)
+{
+	u32 *cfg;
+
+	cfg = devm_kcalloc(dev, num + 1, sizeof(*cfg), GFP_KERNEL);
+	if (!cfg)
+		return -ENOMEM;
+
+	asus_wmi_hwmon_chan->type = type;
+	asus_wmi_hwmon_chan->config = cfg;
+	memset32(cfg, config, num);
+
+	return 0;
+}
+
+/*
+ * For a given sensor item returns details e.g. type (voltage/temperature/fan speed etc), bank etc
+ */
+static int asus_wmi_sensor_info(int index, struct asus_wmi_sensor_info *s)
+{
+	union acpi_object name_obj, data_type_obj, location_obj, source_obj, type_obj;
+	struct acpi_buffer output = { ACPI_ALLOCATE_BUFFER, NULL };
+	u32 args[] = {index, 0};
+	union acpi_object *obj;
+	int err;
+
+	err = asus_wmi_call_method(ASUSWMI_METHODID_GET_INFO, args, &output);
+	if (err)
+		return err;
+
+	s->id = index;
+
+	obj = output.pointer;
+	if (!obj)
+		return -EIO;
+
+	if (obj->type != ACPI_TYPE_PACKAGE) {
+		err = -EIO;
+		goto out_free_obj;
+	}
+
+	if (obj->package.count != 5) {
+		err = -EIO;
+		goto out_free_obj;
+	}
+
+	name_obj = obj->package.elements[0];
+	if (name_obj.type != ACPI_TYPE_STRING) {
+		err = -EIO;
+		goto out_free_obj;
+	}
+
+	strncpy(s->name, name_obj.string.pointer, sizeof(s->name) - 1);
+
+	data_type_obj = obj->package.elements[1];
+	if (data_type_obj.type != ACPI_TYPE_INTEGER) {
+		err = -EIO;
+		goto out_free_obj;
+	}
+
+	s->data_type = data_type_obj.integer.value;
+
+	location_obj = obj->package.elements[2];
+	if (location_obj.type != ACPI_TYPE_INTEGER) {
+		err = -EIO;
+		goto out_free_obj;
+	}
+
+	s->location = location_obj.integer.value;
+
+	source_obj = obj->package.elements[3];
+	if (source_obj.type != ACPI_TYPE_INTEGER) {
+		err = -EIO;
+		goto out_free_obj;
+	}
+
+	s->source = source_obj.integer.value;
+
+	type_obj = obj->package.elements[4];
+	if (type_obj.type != ACPI_TYPE_INTEGER) {
+		err = -EIO;
+		goto out_free_obj;
+	}
+
+	err = 0;
+	s->type = type_obj.integer.value;
+
+out_free_obj:
+	ACPI_FREE(obj);
+	return err;
+}
+
+static int asus_wmi_update_buffer(int source)
+{
+	struct acpi_buffer output = { ACPI_ALLOCATE_BUFFER, NULL };
+	u32 args[] = {source, 0};
+
+	return asus_wmi_call_method(ASUSWMI_METHODID_UPDATE_BUFFER, args, &output);
+}
+
+static int asus_wmi_get_sensor_value(u8 index, long *value)
+{
+	struct acpi_buffer output = { ACPI_ALLOCATE_BUFFER, NULL };
+	u32 args[] = {index, 0};
+	union acpi_object *obj;
+	int err;
+
+	err = asus_wmi_call_method(ASUSWMI_METHODID_GET_VALUE, args, &output);
+	if (err)
+		return err;
+
+	obj = output.pointer;
+	if (!obj)
+		return -EIO;
+
+	if (obj->type != ACPI_TYPE_INTEGER) {
+		err = -EIO;
+		goto out_free_obj;
+	}
+
+	err = 0;
+	*value = obj->integer.value;
+
+out_free_obj:
+	ACPI_FREE(obj);
+	return err;
+}
+
+static int asus_wmi_update_values_for_source(u8 source, struct asus_wmi_sensors *sensor_data)
+{
+	struct asus_wmi_sensor_info *sensor;
+	long value = 0;
+	int ret;
+	int i;
+
+	for (i = 0; i < sensor_data->wmi.sensor_count; i++) {
+		sensor = sensor_data->wmi.info_by_id[i];
+		if (sensor && sensor->source == source) {
+			ret = asus_wmi_get_sensor_value(sensor->id, &value);
+			if (ret)
+				return ret;
+
+			sensor->cached_value = value;
+		}
+	}
+
+	return 0;
+}
+
+static int asus_wmi_scale_sensor_value(u32 value, int data_type)
+{
+	/* FAN_RPM and WATER_FLOW don't need scaling */
+	switch (data_type) {
+	case VOLTAGE:
+		/* value in microVolts */
+		return DIV_ROUND_CLOSEST(value,  KILO);
+	case TEMPERATURE_C:
+		/* value in Celsius */
+		return value * MILLIDEGREE_PER_DEGREE;
+	case CURRENT:
+		/* value in Amperes */
+		return value * MILLI;
+	}
+	return value;
+}
+
+static int asus_wmi_get_cached_value_or_update(const struct asus_wmi_sensor_info *sensor,
+					       struct asus_wmi_sensors *sensor_data,
+					       u32 *value)
+{
+	int ret = 0;
+
+	mutex_lock(&sensor_data->lock);
+
+	if (time_after(jiffies, sensor_data->wmi.source_last_updated[sensor->source] + HZ)) {
+		ret = asus_wmi_update_buffer(sensor->source);
+		if (ret)
+			goto unlock;
+
+		ret = asus_wmi_update_values_for_source(sensor->source, sensor_data);
+		if (ret)
+			goto unlock;
+
+		sensor_data->wmi.source_last_updated[sensor->source] = jiffies;
+	}
+
+	*value = sensor->cached_value;
+
+unlock:
+	mutex_unlock(&sensor_data->lock);
+
+	return ret;
+}
+
+/* Now follow the functions that implement the hwmon interface */
+static int asus_wmi_hwmon_read(struct device *dev, enum hwmon_sensor_types type,
+			       u32 attr, int channel, long *val)
+{
+	const struct asus_wmi_sensor_info *sensor;
+	u32 value = 0;
+	int ret;
+
+	struct asus_wmi_sensors *sensor_data = dev_get_drvdata(dev);
+
+	sensor = *(sensor_data->wmi.info[type] + channel);
+
+	ret = asus_wmi_get_cached_value_or_update(sensor, sensor_data, &value);
+	if (ret)
+		return ret;
+
+	*val = asus_wmi_scale_sensor_value(value, sensor->data_type);
+
+	return ret;
+}
+
+static int asus_wmi_hwmon_read_string(struct device *dev,
+				      enum hwmon_sensor_types type, u32 attr,
+				      int channel, const char **str)
+{
+	struct asus_wmi_sensors *sensor_data = dev_get_drvdata(dev);
+	const struct asus_wmi_sensor_info *sensor;
+
+	sensor = *(sensor_data->wmi.info[type] + channel);
+	*str = sensor->name;
+
+	return 0;
+}
+
+static umode_t asus_wmi_hwmon_is_visible(const void *drvdata,
+					 enum hwmon_sensor_types type, u32 attr,
+					 int channel)
+{
+	const struct asus_wmi_sensors *sensor_data = drvdata;
+	const struct asus_wmi_sensor_info *sensor;
+
+	sensor = *(sensor_data->wmi.info[type] + channel);
+	if (sensor)
+		return 0444;
+
+	return 0;
+}
+
+static const struct hwmon_ops asus_wmi_hwmon_ops = {
+	.is_visible = asus_wmi_hwmon_is_visible,
+	.read = asus_wmi_hwmon_read,
+	.read_string = asus_wmi_hwmon_read_string,
+};
+
+static struct hwmon_chip_info asus_wmi_chip_info = {
+	.ops = &asus_wmi_hwmon_ops,
+	.info = NULL,
+};
+
+static int asus_wmi_configure_sensor_setup(struct device *dev,
+					   struct asus_wmi_sensors *sensor_data)
+{
+	const struct hwmon_channel_info **ptr_asus_wmi_ci;
+	struct hwmon_channel_info *asus_wmi_hwmon_chan;
+	int nr_count[hwmon_max] = {}, nr_types = 0;
+	struct asus_wmi_sensor_info *temp_sensor;
+	const struct hwmon_chip_info *chip_info;
+	enum hwmon_sensor_types type;
+	struct device *hwdev;
+	int i, idx;
+	int err;
+
+	temp_sensor = devm_kcalloc(dev, 1, sizeof(*temp_sensor), GFP_KERNEL);
+	if (!temp_sensor)
+		return -ENOMEM;
+
+	for (i = 0; i < sensor_data->wmi.sensor_count; i++) {
+		err = asus_wmi_sensor_info(i, temp_sensor);
+		if (err)
+			return err;
+
+		switch (temp_sensor->data_type) {
+		case TEMPERATURE_C:
+		case VOLTAGE:
+		case CURRENT:
+		case FAN_RPM:
+		case WATER_FLOW:
+			type = asus_data_types[temp_sensor->data_type];
+			if (!nr_count[type])
+				nr_types++;
+			nr_count[type]++;
+			break;
+		}
+	}
+
+	if (nr_count[hwmon_temp])
+		nr_count[hwmon_chip]++, nr_types++;
+
+	asus_wmi_hwmon_chan = devm_kcalloc(dev, nr_types,
+					   sizeof(*asus_wmi_hwmon_chan),
+					   GFP_KERNEL);
+	if (!asus_wmi_hwmon_chan)
+		return -ENOMEM;
+
+	ptr_asus_wmi_ci = devm_kcalloc(dev, nr_types + 1,
+				       sizeof(*ptr_asus_wmi_ci), GFP_KERNEL);
+	if (!ptr_asus_wmi_ci)
+		return -ENOMEM;
+
+	asus_wmi_chip_info.info = ptr_asus_wmi_ci;
+	chip_info = &asus_wmi_chip_info;
+
+	sensor_data->wmi.info_by_id = devm_kcalloc(dev, sensor_data->wmi.sensor_count,
+						   sizeof(*sensor_data->wmi.info_by_id),
+						   GFP_KERNEL);
+
+	if (!sensor_data->wmi.info_by_id)
+		return -ENOMEM;
+
+	for (type = 0; type < hwmon_max; type++) {
+		if (!nr_count[type])
+			continue;
+
+		err = asus_wmi_hwmon_add_chan_info(asus_wmi_hwmon_chan, dev,
+						   nr_count[type], type,
+						   hwmon_attributes[type]);
+		if (err)
+			return err;
+
+		*ptr_asus_wmi_ci++ = asus_wmi_hwmon_chan++;
+
+		sensor_data->wmi.info[type] = devm_kcalloc(dev,
+							   nr_count[type],
+							   sizeof(*sensor_data->wmi.info),
+							   GFP_KERNEL);
+		if (!sensor_data->wmi.info[type])
+			return -ENOMEM;
+	}
+
+	for (i = sensor_data->wmi.sensor_count - 1; i >= 0; i--) {
+		temp_sensor = devm_kzalloc(dev, sizeof(*temp_sensor), GFP_KERNEL);
+		if (!temp_sensor)
+			return -ENOMEM;
+
+		err = asus_wmi_sensor_info(i, temp_sensor);
+		if (err)
+			continue;
+
+		switch (temp_sensor->data_type) {
+		case TEMPERATURE_C:
+		case VOLTAGE:
+		case CURRENT:
+		case FAN_RPM:
+		case WATER_FLOW:
+			type = asus_data_types[temp_sensor->data_type];
+			idx = --nr_count[type];
+			*(sensor_data->wmi.info[type] + idx) = temp_sensor;
+			sensor_data->wmi.info_by_id[i] = temp_sensor;
+			break;
+		}
+	}
+
+	dev_dbg(dev, "board has %d sensors",
+		sensor_data->wmi.sensor_count);
+
+	hwdev = devm_hwmon_device_register_with_info(dev, "asus_wmi_sensors",
+						     sensor_data, chip_info, NULL);
+
+	return PTR_ERR_OR_ZERO(hwdev);
+}
+
+static int asus_wmi_probe(struct wmi_device *wdev, const void *context)
+{
+	struct asus_wmi_sensors *sensor_data;
+	struct device *dev = &wdev->dev;
+	u32 version = 0;
+
+	if (!dmi_check_system(asus_wmi_dmi_table))
+		return -ENODEV;
+
+	sensor_data = devm_kzalloc(dev, sizeof(*sensor_data), GFP_KERNEL);
+	if (!sensor_data)
+		return -ENOMEM;
+
+	if (asus_wmi_get_version(&version))
+		return -ENODEV;
+
+	if (asus_wmi_get_item_count(&sensor_data->wmi.sensor_count))
+		return -ENODEV;
+
+	if (sensor_data->wmi.sensor_count  <= 0 || version < 2) {
+		dev_info(dev, "version: %u with %d sensors is unsupported\n",
+			 version, sensor_data->wmi.sensor_count);
+
+		return -ENODEV;
+	}
+
+	mutex_init(&sensor_data->lock);
+
+	dev_set_drvdata(dev, sensor_data);
+
+	return asus_wmi_configure_sensor_setup(dev, sensor_data);
+}
+
+static const struct wmi_device_id asus_wmi_id_table[] = {
+	{ ASUSWMI_MONITORING_GUID, NULL },
+	{ }
+};
+
+static struct wmi_driver asus_sensors_wmi_driver = {
+	.driver = {
+		.name = "asus_wmi_sensors",
+	},
+	.id_table = asus_wmi_id_table,
+	.probe = asus_wmi_probe,
+};
+module_wmi_driver(asus_sensors_wmi_driver);
+
+MODULE_AUTHOR("Ed Brindley <kernel@maidavale.org>");
+MODULE_DESCRIPTION("Asus WMI Sensors Driver");
+MODULE_LICENSE("GPL");
-- 
2.33.0