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authorMauro Carvalho Chehab <mchehab+samsung@kernel.org>2019-04-17 11:46:29 +0200
committerGuenter Roeck <linux@roeck-us.net>2019-04-17 19:37:23 +0200
commit7ebd8b66dd9e5a0b65e5ee5e2b8e7ca382ec97b7 (patch)
tree9db30159bd32bec125c7d49e80a79bb7c4da0c8e /Documentation/hwmon/it87
parentdocs: hwmon: convert remaining files to ReST format (diff)
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docs: hwmon: Add an index file and rename docs to *.rst
Now that all files were converted to ReST format, rename them and add an index. Signed-off-by: Mauro Carvalho Chehab <mchehab+samsung@kernel.org> Signed-off-by: Guenter Roeck <linux@roeck-us.net>
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-Kernel driver it87
-==================
-
-Supported chips:
-
- * IT8603E/IT8623E
-
- Prefix: 'it8603'
-
- Addresses scanned: from Super I/O config space (8 I/O ports)
-
- Datasheet: Not publicly available
-
- * IT8620E
-
- Prefix: 'it8620'
-
- Addresses scanned: from Super I/O config space (8 I/O ports)
-
- * IT8628E
-
- Prefix: 'it8628'
-
- 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
-
- * IT8732F
-
- Prefix: 'it8732'
-
- 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
-
- * IT8781F
-
- Prefix: 'it8781'
-
- 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
-
- * IT8786E
-
- Prefix: 'it8786'
-
- Addresses scanned: from Super I/O config space (8 I/O ports)
-
- Datasheet: Not publicly available
-
- * IT8790E
-
- Prefix: 'it8790'
-
- 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, IT8620E, IT8623E, IT8628E,
-IT8705F, IT8712F, IT8716F, IT8718F, IT8720F, IT8721F, IT8726F, IT8728F, IT8732F,
-IT8758E, IT8771E, IT8772E, IT8781F, IT8782F, IT8783E/F, IT8786E, IT8790E, 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, IT8732F, IT8781F, 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/IT8623E is a custom design, hardware monitoring part is similar to
-IT8728F. It only supports 3 fans, 16-bit fan mode, and the full speed mode
-of the fan is not supported (value 0 of pwmX_enable).
-
-The IT8620E and IT8628E are custom designs, hardware monitoring part is similar
-to 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 not
-currently implemented by the driver.
-
-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. On most chips, all
-voltage inputs can measure voltages between 0 and 4.08 volts, with a resolution
-of 0.016 volt. IT8603E, IT8721F/IT8758E and IT8728F can measure between 0 and
-3.06 volts, with a resolution of 0.012 volt. IT8732F can measure between 0 and
-2.8 volts with a resolution of 0.0109 volt. The battery voltage in8 does not
-have 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 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.