Module Parameters¶

• update_vbat: int

  0 if vbat should report power on value, 1 if vbat should be updated aftereach read. Default is 0. On some boards the battery voltage is providedby either the battery or the onboard power supply. Only the first readingat power on will be the actual battery voltage (which the chip doesautomatically). On other boards the battery voltage is always fed tothe chip so can be read at any time. Excessive reading may decreasebattery life but no information is given in the datasheet.

• fix_pwm_polarity int

  Force PWM polarity to active high (DANGEROUS). Some chips aremisconfigured by BIOS - PWM values would be inverted. This option triesto 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, accessedthrough the LPC bus (ISA-like I/O ports). The IT8712F additionally has anSMBus interface to the hardware monitoring functions. This driver nolonger supports this interface though, as it is slower and less reliablethan the ISA access, and was only available on a small number ofmotherboard models.

Description¶

This driver implements support for the IT8603E, IT8620E, IT8623E, IT8628E,IT8705F, IT8712F, IT8716F, IT8718F, IT8720F, IT8721F, IT8726F, IT8728F, IT8732F,IT8758E, IT8771E, IT8772E, IT8781F, IT8782F, IT8783E/F, IT8786E, IT8790E, andSiS950 chips.

These chips are ‘Super I/O chips’, supporting floppy disks, infrared ports,joysticks and other miscellaneous stuff. For hardware monitoring, theyinclude an ‘environment controller’ with 3 temperature sensors, 3 fanrotation speed sensors, 8 voltage sensors, associated alarms, and chassisintrusion detection.

The IT8712F and IT8716F additionally feature VID inputs, used to reportthe Vcore voltage of the processor. The early IT8712F have 5 VID pins,the IT8716F and late IT8712F have 6. They are shared with other functionsthough, 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 valueis stored in the Super-I/O configuration space. Due to technical limitations,this value can currently only be read once at initialization time, sothe driver won’t notice and report changes in the VID value. The twoupper VID bits share their pins with voltage inputs (in5 and in6) so youcan’t have both on a given board.

The IT8716F, IT8718F, IT8720F, IT8721F/IT8758E and later IT8712F revisionshave support for 2 additional fans. The additional fans are supported by thedriver.

The IT8716F, IT8718F, IT8720F, IT8721F/IT8758E, IT8732F, IT8781F, IT8782F,IT8783E/F, and late IT8712F and IT8705F also have optional 16-bit tachometercounters for fans 1 to 3. This is better (no more fan clock divider mess) butnot compatible with the older chips and revisions. The 16-bit tachometer modeis enabled by the driver when one of the above chips is detected.

The IT8726F is just bit enhanced IT8716F with additional hardwarefor AMD power sequencing. Therefore the chip will appear as IT8716Fto userspace applications.

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

The IT8603E/IT8623E is a custom design, hardware monitoring part is similar toIT8728F. It only supports 3 fans, 16-bit fan mode, and the full speed modeof the fan is not supported (value 0 of pwmX_enable).

The IT8620E and IT8628E are custom designs, hardware monitoring part is similarto IT8728F. It only supports 16-bit fan mode. Both chips support up to 6 fans.

The IT8790E supports up to 3 fans. 16-bit fan mode is always enabled.

The IT8732F supports a closed-loop mode for fan control, but this is notcurrently implemented by the driver.

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

Fan rotation speeds are reported in RPM (rotations per minute). An alarm istriggered if the rotation speed has dropped below a programmable limit. When16-bit tachometer counters aren’t used, fan readings can be divided bya programmable divider (1, 2, 4 or 8) to give the readings more range oraccuracy. With a divider of 2, the lowest representable value is around2600 RPM. Not all RPM values can accurately be represented, so some roundingis done.

Voltage sensors (also known as IN sensors) report their values in volts. Analarm is triggered if the voltage has crossed a programmable minimum ormaximum limit. Note that minimum in this case always means ‘closest tozero’; this is important for negative voltage measurements. On most chips, allvoltage inputs can measure voltages between 0 and 4.08 volts, with a resolutionof 0.016 volt. IT8603E, IT8721F/IT8758E and IT8728F can measure between 0 and3.06 volts, with a resolution of 0.012 volt. IT8732F can measure between 0 and2.8 volts with a resolution of 0.0109 volt. The battery voltage in8 does nothave limit registers.

On the IT8603E, IT8620E, IT8628E, IT8721F/IT8758E, IT8732F, IT8781F, IT8782F,and IT8783E/F, some voltage inputs are internal and scaled inside the chip:* in3 (optional)* in7 (optional for IT8781F, 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 bythe mainboard and/or processor itself. It is a value in volts.

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

Out-of-limit readings can also result in beeping, if the chip is properlywired 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 oftenwill 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 atstartup, 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 topwmN_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 isused to drive all fan outputs, which is why pwm2_freq and pwm3_freq areread-only.

Automatic fan speed control (old interface)¶

The driver supports the old interface to automatic fan speed controlwhich is implemented by IT8705F chips up to revision F and IT8712Fchips 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 runningat full speed) while the PWM output of the other 3 trip points can befreely chosen. The temperature of all 4 trip points can be freely chosen.Additionally, trip point 1 has an hysteresis temperature attached, toprevent fast switching between fan on and off.

The chip automatically computes the PWM output value based on the inputtemperature, based on this simple rule: if the temperature value isbetween trip point N and trip point N+1 then the PWM output value isthe one of trip point N. The automatic control mode is less flexiblethan the manual control mode, but it reacts faster, is more robust anddoesn’t use CPU cycles.

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

Temperature offset attributes¶

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