1Kernel driver w83627ehf
   4Supported chips:
   5  * Winbond W83627EHF/EHG (ISA access ONLY)
   6    Prefix: 'w83627ehf'
   7    Addresses scanned: ISA address retrieved from Super I/O registers
   8    Datasheet: not available
   9  * Winbond W83627DHG
  10    Prefix: 'w83627dhg'
  11    Addresses scanned: ISA address retrieved from Super I/O registers
  12    Datasheet: not available
  13  * Winbond W83627DHG-P
  14    Prefix: 'w83627dhg'
  15    Addresses scanned: ISA address retrieved from Super I/O registers
  16    Datasheet: not available
  17  * Winbond W83627UHG
  18    Prefix: 'w83627uhg'
  19    Addresses scanned: ISA address retrieved from Super I/O registers
  20    Datasheet: available from
  21  * Winbond W83667HG
  22    Prefix: 'w83667hg'
  23    Addresses scanned: ISA address retrieved from Super I/O registers
  24    Datasheet: not available
  25  * Winbond W83667HG-B
  26    Prefix: 'w83667hg'
  27    Addresses scanned: ISA address retrieved from Super I/O registers
  28    Datasheet: Available from Nuvoton upon request
  29  * Nuvoton NCT6775F/W83667HG-I
  30    Prefix: 'nct6775'
  31    Addresses scanned: ISA address retrieved from Super I/O registers
  32    Datasheet: Available from Nuvoton upon request
  33  * Nuvoton NCT6776F
  34    Prefix: 'nct6776'
  35    Addresses scanned: ISA address retrieved from Super I/O registers
  36    Datasheet: Available from Nuvoton upon request
  39        Jean Delvare <>
  40        Yuan Mu (Winbond)
  41        Rudolf Marek <>
  42        David Hubbard <>
  43        Gong Jun <>
  48This driver implements support for the Winbond W83627EHF, W83627EHG,
  49W83627DHG, W83627DHG-P, W83627UHG, W83667HG, W83667HG-B, W83667HG-I
  50(NCT6775F), and NCT6776F super I/O chips. We will refer to them collectively
  51as Winbond chips.
  53The chips implement 3 to 4 temperature sensors (9 for NCT6775F and NCT6776F),
  542 to 5 fan rotation speed sensors, 8 to 10 analog voltage sensors, one VID
  55(except for 627UHG), alarms with beep warnings (control unimplemented),
  56and some automatic fan regulation strategies (plus manual fan control mode).
  58The temperature sensor sources on W82677HG-B, NCT6775F, and NCT6776F are
  59configurable. temp4 and higher attributes are only reported if its temperature
  60source differs from the temperature sources of the already reported temperature
  61sensors. The configured source for each of the temperature sensors is provided
  62in tempX_label.
  64Temperatures are measured in degrees Celsius and measurement resolution is 1
  65degC for temp1 and and 0.5 degC for temp2 and temp3. For temp4 and higher,
  66resolution is 1 degC for W83667HG-B and 0.0 degC for NCT6775F and NCT6776F.
  67An alarm is triggered when the temperature gets higher than high limit;
  68it stays on until the temperature falls below the hysteresis value.
  69Alarms are only supported for temp1, temp2, and temp3.
  71Fan rotation speeds are reported in RPM (rotations per minute). An alarm is
  72triggered if the rotation speed has dropped below a programmable limit. Fan
  73readings can be divided by a programmable divider (1, 2, 4, 8, 16, 32, 64 or
  74128) to give the readings more range or accuracy. The driver sets the most
  75suitable fan divisor itself. Some fans might not be present because they
  76share pins with other functions.
  78Voltage sensors (also known as IN sensors) report their values in millivolts.
  79An alarm is triggered if the voltage has crossed a programmable minimum
  80or maximum limit.
  82The driver supports automatic fan control mode known as Thermal Cruise.
  83In this mode, the chip attempts to keep the measured temperature in a
  84predefined temperature range. If the temperature goes out of range, fan
  85is driven slower/faster to reach the predefined range again.
  87The mode works for fan1-fan4. Mapping of temperatures to pwm outputs is as
  90temp1 -> pwm1
  91temp2 -> pwm2
  92temp3 -> pwm3 (not on 627UHG)
  93prog  -> pwm4 (not on 667HG and 667HG-B; the programmable setting is not
  94               supported by the driver)
  96/sys files
  99name - this is a standard hwmon device entry, it contains the name of
 100       the device (see the prefix in the list of supported devices at
 101       the top of this file)
 103pwm[1-4] - this file stores PWM duty cycle or DC value (fan speed) in range:
 104           0 (stop) to 255 (full)
 106pwm[1-4]_enable - this file controls mode of fan/temperature control:
 107        * 1 Manual mode, write to pwm file any value 0-255 (full speed)
 108        * 2 "Thermal Cruise" mode
 109        * 3 "Fan Speed Cruise" mode
 110        * 4 "Smart Fan III" mode
 111        * 5 "Smart Fan IV" mode
 113        SmartFan III mode is not supported on NCT6776F.
 115        SmartFan IV mode is configurable only if it was configured at system
 116        startup, and is only supported for W83677HG-B, NCT6775F, and NCT6776F.
 117        SmartFan IV operational parameters can not be configured at this time,
 118        and the various pwm attributes are not used in SmartFan IV mode.
 119        The attributes can be written to, which is useful if you plan to
 120        configure the system for a different pwm mode. However, the information
 121        returned when reading pwm attributes is unrelated to SmartFan IV
 122        operation.
 124pwm[1-4]_mode - controls if output is PWM or DC level
 125        * 0 DC output (0 - 12v)
 126        * 1 PWM output
 128Thermal Cruise mode
 131If the temperature is in the range defined by:
 133pwm[1-4]_target    - set target temperature, unit millidegree Celsius
 134                     (range 0 - 127000)
 135pwm[1-4]_tolerance - tolerance, unit millidegree Celsius (range 0 - 15000)
 137there are no changes to fan speed. Once the temperature leaves the interval,
 138fan speed increases (temp is higher) or decreases if lower than desired.
 139There are defined steps and times, but not exported by the driver yet.
 141pwm[1-4]_min_output - minimum fan speed (range 1 - 255), when the temperature
 142                      is below defined range.
 143pwm[1-4]_stop_time  - how many milliseconds [ms] must elapse to switch
 144                      corresponding fan off. (when the temperature was below
 145                      defined range).
 146pwm[1-4]_start_output-minimum fan speed (range 1 - 255) when spinning up
 147pwm[1-4]_step_output- rate of fan speed change (1 - 255)
 148pwm[1-4]_stop_output- minimum fan speed (range 1 - 255) when spinning down
 149pwm[1-4]_max_output - maximum fan speed (range 1 - 255), when the temperature
 150                      is above defined range.
 152Note: last six functions are influenced by other control bits, not yet exported
 153      by the driver, so a change might not have any effect.
 155Implementation Details
 158Future driver development should bear in mind that the following registers have
 159different functions on the 627EHF and the 627DHG. Some registers also have
 160different power-on default values, but BIOS should already be loading
 161appropriate defaults. Note that bank selection must be performed as is currently
 162done in the driver for all register addresses.
 1640x49:  only on DHG, selects temperature source for AUX fan, CPU fan0
 1650x4a:  not completely documented for the EHF and the DHG documentation assigns
 166       different behavior to bits 7 and 6, including extending the temperature
 167       input selection to SmartFan I, not just SmartFan III. Testing on the EHF
 168       will reveal whether they are compatible or not.
 1700x58:  Chip ID: 0xa1=EHF 0xc1=DHG
 1710x5e:  only on DHG, has bits to enable "current mode" temperature detection and
 172       critical temperature protection
 1730x45b: only on EHF, bit 3, vin4 alarm (EHF supports 10 inputs, only 9 on DHG)
 1740x552: only on EHF, vin4
 1750x558: only on EHF, vin4 high limit
 1760x559: only on EHF, vin4 low limit
 1770x6b:  only on DHG, SYS fan critical temperature
 1780x6c:  only on DHG, CPU fan0 critical temperature
 1790x6d:  only on DHG, AUX fan critical temperature
 1800x6e:  only on DHG, CPU fan1 critical temperature
 1820x50-0x55 and 0x650-0x657 are marked "Test Register" for the EHF, but "Reserved
 183       Register" for the DHG
 185The DHG also supports PECI, where the DHG queries Intel CPU temperatures, and
 186the ICH8 southbridge gets that data via PECI from the DHG, so that the
 187southbridge drives the fans. And the DHG supports SST, a one-wire serial bus.
 189The DHG-P has an additional automatic fan speed control mode named Smart Fan
 190(TM) III+. This mode is not yet supported by the driver.
 191 kindly hosted by Redpill Linpro AS, provider of Linux consulting and operations services since 1995.