Documentation/hwmon/it87 - kernel/msm-5.4 - Gitiles

 Kernel driver it87
 ==================

 Supported chips:
   * IT8603E
     Prefix: 'it8603'
     Addresses scanned: from Super I/O config space (8 I/O ports)
     Datasheet: Not publicly available
   * IT8705F
     Prefix: 'it87'
     Addresses scanned: from Super I/O config space (8 I/O ports)
     Datasheet: Once publicly available at the ITE website, but no longer
   * IT8712F
     Prefix: 'it8712'
     Addresses scanned: from Super I/O config space (8 I/O ports)
     Datasheet: Once publicly available at the ITE website, but no longer
   * IT8716F/IT8726F
     Prefix: 'it8716'
     Addresses scanned: from Super I/O config space (8 I/O ports)
     Datasheet: Once publicly available at the ITE website, but no longer
   * IT8718F
     Prefix: 'it8718'
     Addresses scanned: from Super I/O config space (8 I/O ports)
     Datasheet: Once publicly available at the ITE website, but no longer
   * IT8720F
     Prefix: 'it8720'
     Addresses scanned: from Super I/O config space (8 I/O ports)
     Datasheet: Not publicly available
   * IT8721F/IT8758E
     Prefix: 'it8721'
     Addresses scanned: from Super I/O config space (8 I/O ports)
     Datasheet: Not publicly available
   * IT8728F
     Prefix: 'it8728'
     Addresses scanned: from Super I/O config space (8 I/O ports)
     Datasheet: Not publicly available
   * IT8771E
     Prefix: 'it8771'
     Addresses scanned: from Super I/O config space (8 I/O ports)
     Datasheet: Not publicly available
   * IT8772E
     Prefix: 'it8772'
     Addresses scanned: from Super I/O config space (8 I/O ports)
     Datasheet: Not publicly available
   * IT8782F
     Prefix: 'it8782'
     Addresses scanned: from Super I/O config space (8 I/O ports)
     Datasheet: Not publicly available
   * IT8783E/F
     Prefix: 'it8783'
     Addresses scanned: from Super I/O config space (8 I/O ports)
     Datasheet: Not publicly available
   * SiS950   [clone of IT8705F]
     Prefix: 'it87'
     Addresses scanned: from Super I/O config space (8 I/O ports)
     Datasheet: No longer be available

 Authors:
     Christophe Gauthron
     Jean Delvare <jdelvare@suse.de>


 Module Parameters
 -----------------

 * update_vbat: int

   0 if vbat should report power on value, 1 if vbat should be updated after
   each read. Default is 0. On some boards the battery voltage is provided
   by either the battery or the onboard power supply. Only the first reading
   at power on will be the actual battery voltage (which the chip does
   automatically). On other boards the battery voltage is always fed to
   the chip so can be read at any time. Excessive reading may decrease
   battery life but no information is given in the datasheet.

 * fix_pwm_polarity int

   Force PWM polarity to active high (DANGEROUS). Some chips are
   misconfigured by BIOS - PWM values would be inverted. This option tries
   to fix this. Please contact your BIOS manufacturer and ask him for fix.


 Hardware Interfaces
 -------------------

 All the chips supported by this driver are LPC Super-I/O chips, accessed
 through the LPC bus (ISA-like I/O ports). The IT8712F additionally has an
 SMBus interface to the hardware monitoring functions. This driver no
 longer supports this interface though, as it is slower and less reliable
 than the ISA access, and was only available on a small number of
 motherboard models.


 Description
 -----------

 This driver implements support for the IT8603E, IT8705F, IT8712F, IT8716F,
 IT8718F, IT8720F, IT8721F, IT8726F, IT8728F, IT8758E, IT8771E, IT8772E,
 IT8782F, IT8783E/F, and SiS950 chips.

 These chips are 'Super I/O chips', supporting floppy disks, infrared ports,
 joysticks and other miscellaneous stuff. For hardware monitoring, they
 include an 'environment controller' with 3 temperature sensors, 3 fan
 rotation speed sensors, 8 voltage sensors, associated alarms, and chassis
 intrusion detection.

 The IT8712F and IT8716F additionally feature VID inputs, used to report
 the Vcore voltage of the processor. The early IT8712F have 5 VID pins,
 the IT8716F and late IT8712F have 6. They are shared with other functions
 though, so the functionality may not be available on a given system.

 The IT8718F and IT8720F also features VID inputs (up to 8 pins) but the value
 is stored in the Super-I/O configuration space. Due to technical limitations,
 this value can currently only be read once at initialization time, so
 the driver won't notice and report changes in the VID value. The two
 upper VID bits share their pins with voltage inputs (in5 and in6) so you
 can't have both on a given board.

 The IT8716F, IT8718F, IT8720F, IT8721F/IT8758E and later IT8712F revisions
 have support for 2 additional fans. The additional fans are supported by the
 driver.

 The IT8716F, IT8718F, IT8720F, IT8721F/IT8758E, IT8782F, IT8783E/F, and late
 IT8712F and IT8705F also have optional 16-bit tachometer counters for fans 1 to
 3. This is better (no more fan clock divider mess) but not compatible with the
 older chips and revisions. The 16-bit tachometer mode is enabled by the driver
 when one of the above chips is detected.

 The IT8726F is just bit enhanced IT8716F with additional hardware
 for AMD power sequencing. Therefore the chip will appear as IT8716F
 to userspace applications.

 The IT8728F, IT8771E, and IT8772E are considered compatible with the IT8721F,
 until a datasheet becomes available (hopefully.)

 The IT8603E is a custom design, hardware monitoring part is similar to
 IT8728F. It only supports 16-bit fan mode, the full speed mode of the
 fan is not supported (value 0 of pwmX_enable).

 Temperatures are measured in degrees Celsius. An alarm is triggered once
 when the Overtemperature Shutdown limit is crossed.

 Fan rotation speeds are reported in RPM (rotations per minute). An alarm is
 triggered if the rotation speed has dropped below a programmable limit. When
 16-bit tachometer counters aren't used, fan readings can be divided by
 a programmable divider (1, 2, 4 or 8) to give the readings more range or
 accuracy. With a divider of 2, the lowest representable value is around
 2600 RPM. Not all RPM values can accurately be represented, so some rounding
 is done.

 Voltage sensors (also known as IN sensors) report their values in volts. An
 alarm is triggered if the voltage has crossed a programmable minimum or
 maximum limit. Note that minimum in this case always means 'closest to
 zero'; this is important for negative voltage measurements. All voltage
 inputs can measure voltages between 0 and 4.08 volts, with a resolution of
 0.016 volt (except IT8603E, IT8721F/IT8758E and IT8728F: 0.012 volt.) The
 battery voltage in8 does not have limit registers.

 On the IT8603E, IT8721F/IT8758E, IT8782F, and IT8783E/F, some voltage inputs
 are internal and scaled inside the chip:
 * in3 (optional)
 * in7 (optional for IT8782F and IT8783E/F)
 * in8 (always)
 * in9 (relevant for IT8603E only)
 The driver handles this transparently so user-space doesn't have to care.

 The VID lines (IT8712F/IT8716F/IT8718F/IT8720F) encode the core voltage value:
 the voltage level your processor should work with. This is hardcoded by
 the mainboard and/or processor itself. It is a value in volts.

 If an alarm triggers, it will remain triggered until the hardware register
 is read at least once. This means that the cause for the alarm may already
 have disappeared! Note that in the current implementation, all hardware
 registers are read whenever any data is read (unless it is less than 1.5
 seconds since the last update). This means that you can easily miss
 once-only alarms.

 Out-of-limit readings can also result in beeping, if the chip is properly
 wired and configured. Beeping can be enabled or disabled per sensor type
 (temperatures, voltages and fans.)

 The IT87xx only updates its values each 1.5 seconds; reading it more often
 will do no harm, but will return 'old' values.

 To change sensor N to a thermistor, 'echo 4 > tempN_type' where N is 1, 2,
 or 3. To change sensor N to a thermal diode, 'echo 3 > tempN_type'.
 Give 0 for unused sensor. Any other value is invalid. To configure this at
 startup, consult lm_sensors's /etc/sensors.conf. (4 = thermistor;
 3 = thermal diode)


 Fan speed control
 -----------------

 The fan speed control features are limited to manual PWM mode. Automatic
 "Smart Guardian" mode control handling is only implemented for older chips
 (see below.) However if you want to go for "manual mode" just write 1 to
 pwmN_enable.

 If you are only able to control the fan speed with very small PWM values,
 try lowering the PWM base frequency (pwm1_freq). Depending on the fan,
 it may give you a somewhat greater control range. The same frequency is
 used to drive all fan outputs, which is why pwm2_freq and pwm3_freq are
 read-only.


 Automatic fan speed control (old interface)
 -------------------------------------------

 The driver supports the old interface to automatic fan speed control
 which is implemented by IT8705F chips up to revision F and IT8712F
 chips up to revision G.

 This interface implements 4 temperature vs. PWM output trip points.
 The PWM output of trip point 4 is always the maximum value (fan running
 at full speed) while the PWM output of the other 3 trip points can be
 freely chosen. The temperature of all 4 trip points can be freely chosen.
 Additionally, trip point 1 has an hysteresis temperature attached, to
 prevent fast switching between fan on and off.

 The chip automatically computes the PWM output value based on the input
 temperature, based on this simple rule: if the temperature value is
 between trip point N and trip point N+1 then the PWM output value is
 the one of trip point N. The automatic control mode is less flexible
 than the manual control mode, but it reacts faster, is more robust and
 doesn't use CPU cycles.

 Trip points must be set properly before switching to automatic fan speed
 control mode. The driver will perform basic integrity checks before
 actually switching to automatic control mode.


 Temperature offset attributes
 -----------------------------

 The driver supports temp[1-3]_offset sysfs attributes to adjust the reported
 temperature for thermal diodes or diode-connected thermal transistors.
 If a temperature sensor is configured for thermistors, the attribute values
 are ignored. If the thermal sensor type is Intel PECI, the temperature offset
 must be programmed to the critical CPU temperature.
	Kernel driver it87
	==================

	Supported chips:
	* IT8603E
	Prefix: 'it8603'
	Addresses scanned: from Super I/O config space (8 I/O ports)
	Datasheet: Not publicly available
	* IT8705F
	Prefix: 'it87'
	Addresses scanned: from Super I/O config space (8 I/O ports)
	Datasheet: Once publicly available at the ITE website, but no longer
	* IT8712F
	Prefix: 'it8712'
	Addresses scanned: from Super I/O config space (8 I/O ports)
	Datasheet: Once publicly available at the ITE website, but no longer
	* IT8716F/IT8726F
	Prefix: 'it8716'
	Addresses scanned: from Super I/O config space (8 I/O ports)
	Datasheet: Once publicly available at the ITE website, but no longer
	* IT8718F
	Prefix: 'it8718'
	Addresses scanned: from Super I/O config space (8 I/O ports)
	Datasheet: Once publicly available at the ITE website, but no longer
	* IT8720F
	Prefix: 'it8720'
	Addresses scanned: from Super I/O config space (8 I/O ports)
	Datasheet: Not publicly available
	* IT8721F/IT8758E
	Prefix: 'it8721'
	Addresses scanned: from Super I/O config space (8 I/O ports)
	Datasheet: Not publicly available
	* IT8728F
	Prefix: 'it8728'
	Addresses scanned: from Super I/O config space (8 I/O ports)
	Datasheet: Not publicly available
	* IT8771E
	Prefix: 'it8771'
	Addresses scanned: from Super I/O config space (8 I/O ports)
	Datasheet: Not publicly available
	* IT8772E
	Prefix: 'it8772'
	Addresses scanned: from Super I/O config space (8 I/O ports)
	Datasheet: Not publicly available
	* IT8782F
	Prefix: 'it8782'
	Addresses scanned: from Super I/O config space (8 I/O ports)
	Datasheet: Not publicly available
	* IT8783E/F
	Prefix: 'it8783'
	Addresses scanned: from Super I/O config space (8 I/O ports)
	Datasheet: Not publicly available
	* SiS950 [clone of IT8705F]
	Prefix: 'it87'
	Addresses scanned: from Super I/O config space (8 I/O ports)
	Datasheet: No longer be available

	Authors:
	Christophe Gauthron
	Jean Delvare <jdelvare@suse.de>


	Module Parameters
	-----------------

	* update_vbat: int

	0 if vbat should report power on value, 1 if vbat should be updated after
	each read. Default is 0. On some boards the battery voltage is provided
	by either the battery or the onboard power supply. Only the first reading
	at power on will be the actual battery voltage (which the chip does
	automatically). On other boards the battery voltage is always fed to
	the chip so can be read at any time. Excessive reading may decrease
	battery life but no information is given in the datasheet.

	* fix_pwm_polarity int

	Force PWM polarity to active high (DANGEROUS). Some chips are
	misconfigured by BIOS - PWM values would be inverted. This option tries
	to fix this. Please contact your BIOS manufacturer and ask him for fix.


	Hardware Interfaces
	-------------------

	All the chips supported by this driver are LPC Super-I/O chips, accessed
	through the LPC bus (ISA-like I/O ports). The IT8712F additionally has an
	SMBus interface to the hardware monitoring functions. This driver no
	longer supports this interface though, as it is slower and less reliable
	than the ISA access, and was only available on a small number of
	motherboard models.


	Description
	-----------

	This driver implements support for the IT8603E, IT8705F, IT8712F, IT8716F,
	IT8718F, IT8720F, IT8721F, IT8726F, IT8728F, IT8758E, IT8771E, IT8772E,
	IT8782F, IT8783E/F, and SiS950 chips.

	These chips are 'Super I/O chips', supporting floppy disks, infrared ports,
	joysticks and other miscellaneous stuff. For hardware monitoring, they
	include an 'environment controller' with 3 temperature sensors, 3 fan
	rotation speed sensors, 8 voltage sensors, associated alarms, and chassis
	intrusion detection.

	The IT8712F and IT8716F additionally feature VID inputs, used to report
	the Vcore voltage of the processor. The early IT8712F have 5 VID pins,
	the IT8716F and late IT8712F have 6. They are shared with other functions
	though, so the functionality may not be available on a given system.

	The IT8718F and IT8720F also features VID inputs (up to 8 pins) but the value
	is stored in the Super-I/O configuration space. Due to technical limitations,
	this value can currently only be read once at initialization time, so
	the driver won't notice and report changes in the VID value. The two
	upper VID bits share their pins with voltage inputs (in5 and in6) so you
	can't have both on a given board.

	The IT8716F, IT8718F, IT8720F, IT8721F/IT8758E and later IT8712F revisions
	have support for 2 additional fans. The additional fans are supported by the
	driver.

	The IT8716F, IT8718F, IT8720F, IT8721F/IT8758E, IT8782F, IT8783E/F, and late
	IT8712F and IT8705F also have optional 16-bit tachometer counters for fans 1 to
	3. This is better (no more fan clock divider mess) but not compatible with the
	older chips and revisions. The 16-bit tachometer mode is enabled by the driver
	when one of the above chips is detected.

	The IT8726F is just bit enhanced IT8716F with additional hardware
	for AMD power sequencing. Therefore the chip will appear as IT8716F
	to userspace applications.

	The IT8728F, IT8771E, and IT8772E are considered compatible with the IT8721F,
	until a datasheet becomes available (hopefully.)

	The IT8603E is a custom design, hardware monitoring part is similar to
	IT8728F. It only supports 16-bit fan mode, the full speed mode of the
	fan is not supported (value 0 of pwmX_enable).

	Temperatures are measured in degrees Celsius. An alarm is triggered once
	when the Overtemperature Shutdown limit is crossed.

	Fan rotation speeds are reported in RPM (rotations per minute). An alarm is
	triggered if the rotation speed has dropped below a programmable limit. When
	16-bit tachometer counters aren't used, fan readings can be divided by
	a programmable divider (1, 2, 4 or 8) to give the readings more range or
	accuracy. With a divider of 2, the lowest representable value is around
	2600 RPM. Not all RPM values can accurately be represented, so some rounding
	is done.

	Voltage sensors (also known as IN sensors) report their values in volts. An
	alarm is triggered if the voltage has crossed a programmable minimum or
	maximum limit. Note that minimum in this case always means 'closest to
	zero'; this is important for negative voltage measurements. All voltage
	inputs can measure voltages between 0 and 4.08 volts, with a resolution of
	0.016 volt (except IT8603E, IT8721F/IT8758E and IT8728F: 0.012 volt.) The
	battery voltage in8 does not have limit registers.

	On the IT8603E, IT8721F/IT8758E, IT8782F, and IT8783E/F, some voltage inputs
	are internal and scaled inside the chip:
	* in3 (optional)
	* in7 (optional for IT8782F and IT8783E/F)
	* in8 (always)
	* in9 (relevant for IT8603E only)
	The driver handles this transparently so user-space doesn't have to care.

	The VID lines (IT8712F/IT8716F/IT8718F/IT8720F) encode the core voltage value:
	the voltage level your processor should work with. This is hardcoded by
	the mainboard and/or processor itself. It is a value in volts.

	If an alarm triggers, it will remain triggered until the hardware register
	is read at least once. This means that the cause for the alarm may already
	have disappeared! Note that in the current implementation, all hardware
	registers are read whenever any data is read (unless it is less than 1.5
	seconds since the last update). This means that you can easily miss
	once-only alarms.

	Out-of-limit readings can also result in beeping, if the chip is properly
	wired and configured. Beeping can be enabled or disabled per sensor type
	(temperatures, voltages and fans.)

	The IT87xx only updates its values each 1.5 seconds; reading it more often
	will do no harm, but will return 'old' values.

	To change sensor N to a thermistor, 'echo 4 > tempN_type' where N is 1, 2,
	or 3. To change sensor N to a thermal diode, 'echo 3 > tempN_type'.
	Give 0 for unused sensor. Any other value is invalid. To configure this at
	startup, consult lm_sensors's /etc/sensors.conf. (4 = thermistor;
	3 = thermal diode)


	Fan speed control
	-----------------

	The fan speed control features are limited to manual PWM mode. Automatic
	"Smart Guardian" mode control handling is only implemented for older chips
	(see below.) However if you want to go for "manual mode" just write 1 to
	pwmN_enable.

	If you are only able to control the fan speed with very small PWM values,
	try lowering the PWM base frequency (pwm1_freq). Depending on the fan,
	it may give you a somewhat greater control range. The same frequency is
	used to drive all fan outputs, which is why pwm2_freq and pwm3_freq are
	read-only.


	Automatic fan speed control (old interface)
	-------------------------------------------

	The driver supports the old interface to automatic fan speed control
	which is implemented by IT8705F chips up to revision F and IT8712F
	chips up to revision G.

	This interface implements 4 temperature vs. PWM output trip points.
	The PWM output of trip point 4 is always the maximum value (fan running
	at full speed) while the PWM output of the other 3 trip points can be
	freely chosen. The temperature of all 4 trip points can be freely chosen.
	Additionally, trip point 1 has an hysteresis temperature attached, to
	prevent fast switching between fan on and off.

	The chip automatically computes the PWM output value based on the input
	temperature, based on this simple rule: if the temperature value is
	between trip point N and trip point N+1 then the PWM output value is
	the one of trip point N. The automatic control mode is less flexible
	than the manual control mode, but it reacts faster, is more robust and
	doesn't use CPU cycles.

	Trip points must be set properly before switching to automatic fan speed
	control mode. The driver will perform basic integrity checks before
	actually switching to automatic control mode.


	Temperature offset attributes
	-----------------------------

	The driver supports temp[1-3]_offset sysfs attributes to adjust the reported
	temperature for thermal diodes or diode-connected thermal transistors.
	If a temperature sensor is configured for thermistors, the attribute values
	are ignored. If the thermal sensor type is Intel PECI, the temperature offset
	must be programmed to the critical CPU temperature.