184 lines
7.9 KiB
Plaintext
184 lines
7.9 KiB
Plaintext
Kernel driver it87
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==================
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Supported chips:
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* IT8705F
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Prefix: 'it87'
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Addresses scanned: from Super I/O config space (8 I/O ports)
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Datasheet: Once publicly available at the ITE website, but no longer
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* IT8712F
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Prefix: 'it8712'
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Addresses scanned: from Super I/O config space (8 I/O ports)
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Datasheet: Once publicly available at the ITE website, but no longer
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* IT8716F/IT8726F
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Prefix: 'it8716'
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Addresses scanned: from Super I/O config space (8 I/O ports)
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Datasheet: Once publicly available at the ITE website, but no longer
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* IT8718F
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Prefix: 'it8718'
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Addresses scanned: from Super I/O config space (8 I/O ports)
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Datasheet: Once publicly available at the ITE website, but no longer
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* IT8720F
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Prefix: 'it8720'
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Addresses scanned: from Super I/O config space (8 I/O ports)
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Datasheet: Not publicly available
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* SiS950 [clone of IT8705F]
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Prefix: 'it87'
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Addresses scanned: from Super I/O config space (8 I/O ports)
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Datasheet: No longer be available
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Authors:
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Christophe Gauthron
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Jean Delvare <khali@linux-fr.org>
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Module Parameters
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-----------------
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* update_vbat: int
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0 if vbat should report power on value, 1 if vbat should be updated after
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each read. Default is 0. On some boards the battery voltage is provided
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by either the battery or the onboard power supply. Only the first reading
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at power on will be the actual battery voltage (which the chip does
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automatically). On other boards the battery voltage is always fed to
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the chip so can be read at any time. Excessive reading may decrease
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battery life but no information is given in the datasheet.
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* fix_pwm_polarity int
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Force PWM polarity to active high (DANGEROUS). Some chips are
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misconfigured by BIOS - PWM values would be inverted. This option tries
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to fix this. Please contact your BIOS manufacturer and ask him for fix.
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Hardware Interfaces
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-------------------
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All the chips suported by this driver are LPC Super-I/O chips, accessed
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through the LPC bus (ISA-like I/O ports). The IT8712F additionally has an
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SMBus interface to the hardware monitoring functions. This driver no
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longer supports this interface though, as it is slower and less reliable
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than the ISA access, and was only available on a small number of
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motherboard models.
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Description
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-----------
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This driver implements support for the IT8705F, IT8712F, IT8716F,
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IT8718F, IT8720F, IT8726F and SiS950 chips.
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These chips are 'Super I/O chips', supporting floppy disks, infrared ports,
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joysticks and other miscellaneous stuff. For hardware monitoring, they
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include an 'environment controller' with 3 temperature sensors, 3 fan
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rotation speed sensors, 8 voltage sensors, and associated alarms.
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The IT8712F and IT8716F additionally feature VID inputs, used to report
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the Vcore voltage of the processor. The early IT8712F have 5 VID pins,
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the IT8716F and late IT8712F have 6. They are shared with other functions
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though, so the functionality may not be available on a given system.
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The IT8718F and IT8720F also features VID inputs (up to 8 pins) but the value
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is stored in the Super-I/O configuration space. Due to technical limitations,
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this value can currently only be read once at initialization time, so
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the driver won't notice and report changes in the VID value. The two
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upper VID bits share their pins with voltage inputs (in5 and in6) so you
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can't have both on a given board.
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The IT8716F, IT8718F, IT8720F and later IT8712F revisions have support for
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2 additional fans. The additional fans are supported by the driver.
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The IT8716F, IT8718F and IT8720F, and late IT8712F and IT8705F also have
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optional 16-bit tachometer counters for fans 1 to 3. This is better (no more
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fan clock divider mess) but not compatible with the older chips and
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revisions. The 16-bit tachometer mode is enabled by the driver when one
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of the above chips is detected.
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The IT8726F is just bit enhanced IT8716F with additional hardware
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for AMD power sequencing. Therefore the chip will appear as IT8716F
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to userspace applications.
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Temperatures are measured in degrees Celsius. An alarm is triggered once
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when the Overtemperature Shutdown limit is crossed.
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Fan rotation speeds are reported in RPM (rotations per minute). An alarm is
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triggered if the rotation speed has dropped below a programmable limit. When
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16-bit tachometer counters aren't used, fan readings can be divided by
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a programmable divider (1, 2, 4 or 8) to give the readings more range or
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accuracy. With a divider of 2, the lowest representable value is around
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2600 RPM. Not all RPM values can accurately be represented, so some rounding
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is done.
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Voltage sensors (also known as IN sensors) report their values in volts. An
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alarm is triggered if the voltage has crossed a programmable minimum or
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maximum limit. Note that minimum in this case always means 'closest to
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zero'; this is important for negative voltage measurements. All voltage
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inputs can measure voltages between 0 and 4.08 volts, with a resolution of
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0.016 volt. The battery voltage in8 does not have limit registers.
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The VID lines (IT8712F/IT8716F/IT8718F/IT8720F) encode the core voltage value:
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the voltage level your processor should work with. This is hardcoded by
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the mainboard and/or processor itself. It is a value in volts.
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If an alarm triggers, it will remain triggered until the hardware register
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is read at least once. This means that the cause for the alarm may already
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have disappeared! Note that in the current implementation, all hardware
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registers are read whenever any data is read (unless it is less than 1.5
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seconds since the last update). This means that you can easily miss
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once-only alarms.
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Out-of-limit readings can also result in beeping, if the chip is properly
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wired and configured. Beeping can be enabled or disabled per sensor type
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(temperatures, voltages and fans.)
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The IT87xx only updates its values each 1.5 seconds; reading it more often
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will do no harm, but will return 'old' values.
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To change sensor N to a thermistor, 'echo 4 > tempN_type' where N is 1, 2,
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or 3. To change sensor N to a thermal diode, 'echo 3 > tempN_type'.
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Give 0 for unused sensor. Any other value is invalid. To configure this at
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startup, consult lm_sensors's /etc/sensors.conf. (4 = thermistor;
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3 = thermal diode)
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Fan speed control
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-----------------
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The fan speed control features are limited to manual PWM mode. Automatic
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"Smart Guardian" mode control handling is only implemented for older chips
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(see below.) However if you want to go for "manual mode" just write 1 to
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pwmN_enable.
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If you are only able to control the fan speed with very small PWM values,
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try lowering the PWM base frequency (pwm1_freq). Depending on the fan,
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it may give you a somewhat greater control range. The same frequency is
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used to drive all fan outputs, which is why pwm2_freq and pwm3_freq are
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read-only.
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Automatic fan speed control (old interface)
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-------------------------------------------
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The driver supports the old interface to automatic fan speed control
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which is implemented by IT8705F chips up to revision F and IT8712F
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chips up to revision G.
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This interface implements 4 temperature vs. PWM output trip points.
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The PWM output of trip point 4 is always the maximum value (fan running
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at full speed) while the PWM output of the other 3 trip points can be
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freely chosen. The temperature of all 4 trip points can be freely chosen.
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Additionally, trip point 1 has an hysteresis temperature attached, to
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prevent fast switching between fan on and off.
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The chip automatically computes the PWM output value based on the input
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temperature, based on this simple rule: if the temperature value is
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between trip point N and trip point N+1 then the PWM output value is
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the one of trip point N. The automatic control mode is less flexible
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than the manual control mode, but it reacts faster, is more robust and
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doesn't use CPU cycles.
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Trip points must be set properly before switching to automatic fan speed
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control mode. The driver will perform basic integrity checks before
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actually switching to automatic control mode.
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