Documentation/hwmon/it87

   1 Kernel driver it87
   2 ==================
   3
   4 Supported chips:
   5   * IT8603E/IT8623E
   6     Prefix: 'it8603'
   7     Addresses scanned: from Super I/O config space (8 I/O ports)
   8     Datasheet: Not publicly available
   9   * IT8705F
  10     Prefix: 'it87'
  11     Addresses scanned: from Super I/O config space (8 I/O ports)
  12     Datasheet: Once publicly available at the ITE website, but no longer
  13   * IT8712F
  14     Prefix: 'it8712'
  15     Addresses scanned: from Super I/O config space (8 I/O ports)
  16     Datasheet: Once publicly available at the ITE website, but no longer
  17   * IT8716F/IT8726F
  18     Prefix: 'it8716'
  19     Addresses scanned: from Super I/O config space (8 I/O ports)
  20     Datasheet: Once publicly available at the ITE website, but no longer
  21   * IT8718F
  22     Prefix: 'it8718'
  23     Addresses scanned: from Super I/O config space (8 I/O ports)
  24     Datasheet: Once publicly available at the ITE website, but no longer
  25   * IT8720F
  26     Prefix: 'it8720'
  27     Addresses scanned: from Super I/O config space (8 I/O ports)
  28     Datasheet: Not publicly available
  29   * IT8721F/IT8758E
  30     Prefix: 'it8721'
  31     Addresses scanned: from Super I/O config space (8 I/O ports)
  32     Datasheet: Not publicly available
  33   * IT8728F
  34     Prefix: 'it8728'
  35     Addresses scanned: from Super I/O config space (8 I/O ports)
  36     Datasheet: Not publicly available
  37   * IT8771E
  38     Prefix: 'it8771'
  39     Addresses scanned: from Super I/O config space (8 I/O ports)
  40     Datasheet: Not publicly available
  41   * IT8772E
  42     Prefix: 'it8772'
  43     Addresses scanned: from Super I/O config space (8 I/O ports)
  44     Datasheet: Not publicly available
  45   * IT8782F
  46     Prefix: 'it8782'
  47     Addresses scanned: from Super I/O config space (8 I/O ports)
  48     Datasheet: Not publicly available
  49   * IT8783E/F
  50     Prefix: 'it8783'
  51     Addresses scanned: from Super I/O config space (8 I/O ports)
  52     Datasheet: Not publicly available
  53   * SiS950   [clone of IT8705F]
  54     Prefix: 'it87'
  55     Addresses scanned: from Super I/O config space (8 I/O ports)
  56     Datasheet: No longer be available
  57
  58 Authors:
  59     Christophe Gauthron
  60     Jean Delvare <jdelvare@suse.de>
  61
  62
  63 Module Parameters
  64 -----------------
  65
  66 * update_vbat: int
  67
  68   0 if vbat should report power on value, 1 if vbat should be updated after
  69   each read. Default is 0. On some boards the battery voltage is provided
  70   by either the battery or the onboard power supply. Only the first reading
  71   at power on will be the actual battery voltage (which the chip does
  72   automatically). On other boards the battery voltage is always fed to
  73   the chip so can be read at any time. Excessive reading may decrease
  74   battery life but no information is given in the datasheet.
  75
  76 * fix_pwm_polarity int
  77
  78   Force PWM polarity to active high (DANGEROUS). Some chips are
  79   misconfigured by BIOS - PWM values would be inverted. This option tries
  80   to fix this. Please contact your BIOS manufacturer and ask him for fix.
  81
  82
  83 Hardware Interfaces
  84 -------------------
  85
  86 All the chips supported by this driver are LPC Super-I/O chips, accessed
  87 through the LPC bus (ISA-like I/O ports). The IT8712F additionally has an
  88 SMBus interface to the hardware monitoring functions. This driver no
  89 longer supports this interface though, as it is slower and less reliable
  90 than the ISA access, and was only available on a small number of
  91 motherboard models.
  92
  93
  94 Description
  95 -----------
  96
  97 This driver implements support for the IT8603E, IT8623E, IT8705F, IT8712F,
  98 IT8716F, IT8718F, IT8720F, IT8721F, IT8726F, IT8728F, IT8758E, IT8771E,
  99 IT8772E, IT8782F, IT8783E/F, and SiS950 chips.
 100
 101 These chips are 'Super I/O chips', supporting floppy disks, infrared ports,
 102 joysticks and other miscellaneous stuff. For hardware monitoring, they
 103 include an 'environment controller' with 3 temperature sensors, 3 fan
 104 rotation speed sensors, 8 voltage sensors, associated alarms, and chassis
 105 intrusion detection.
 106
 107 The IT8712F and IT8716F additionally feature VID inputs, used to report
 108 the Vcore voltage of the processor. The early IT8712F have 5 VID pins,
 109 the IT8716F and late IT8712F have 6. They are shared with other functions
 110 though, so the functionality may not be available on a given system.
 111
 112 The IT8718F and IT8720F also features VID inputs (up to 8 pins) but the value
 113 is stored in the Super-I/O configuration space. Due to technical limitations,
 114 this value can currently only be read once at initialization time, so
 115 the driver won't notice and report changes in the VID value. The two
 116 upper VID bits share their pins with voltage inputs (in5 and in6) so you
 117 can't have both on a given board.
 118
 119 The IT8716F, IT8718F, IT8720F, IT8721F/IT8758E and later IT8712F revisions
 120 have support for 2 additional fans. The additional fans are supported by the
 121 driver.
 122
 123 The IT8716F, IT8718F, IT8720F, IT8721F/IT8758E, IT8782F, IT8783E/F, and late
 124 IT8712F and IT8705F also have optional 16-bit tachometer counters for fans 1 to
 125 3. This is better (no more fan clock divider mess) but not compatible with the
 126 older chips and revisions. The 16-bit tachometer mode is enabled by the driver
 127 when one of the above chips is detected.
 128
 129 The IT8726F is just bit enhanced IT8716F with additional hardware
 130 for AMD power sequencing. Therefore the chip will appear as IT8716F
 131 to userspace applications.
 132
 133 The IT8728F, IT8771E, and IT8772E are considered compatible with the IT8721F,
 134 until a datasheet becomes available (hopefully.)
 135
 136 The IT8603E/IT8623E is a custom design, hardware monitoring part is similar to
 137 IT8728F. It only supports 16-bit fan mode, the full speed mode of the
 138 fan is not supported (value 0 of pwmX_enable).
 139
 140 Temperatures are measured in degrees Celsius. An alarm is triggered once
 141 when the Overtemperature Shutdown limit is crossed.
 142
 143 Fan rotation speeds are reported in RPM (rotations per minute). An alarm is
 144 triggered if the rotation speed has dropped below a programmable limit. When
 145 16-bit tachometer counters aren't used, fan readings can be divided by
 146 a programmable divider (1, 2, 4 or 8) to give the readings more range or
 147 accuracy. With a divider of 2, the lowest representable value is around
 148 2600 RPM. Not all RPM values can accurately be represented, so some rounding
 149 is done.
 150
 151 Voltage sensors (also known as IN sensors) report their values in volts. An
 152 alarm is triggered if the voltage has crossed a programmable minimum or
 153 maximum limit. Note that minimum in this case always means 'closest to
 154 zero'; this is important for negative voltage measurements. All voltage
 155 inputs can measure voltages between 0 and 4.08 volts, with a resolution of
 156 0.016 volt (except IT8603E, IT8721F/IT8758E and IT8728F: 0.012 volt.) The
 157 battery voltage in8 does not have limit registers.
 158
 159 On the IT8603E, IT8721F/IT8758E, IT8782F, and IT8783E/F, some voltage inputs
 160 are internal and scaled inside the chip:
 161 * in3 (optional)
 162 * in7 (optional for IT8782F and IT8783E/F)
 163 * in8 (always)
 164 * in9 (relevant for IT8603E only)
 165 The driver handles this transparently so user-space doesn't have to care.
 166
 167 The VID lines (IT8712F/IT8716F/IT8718F/IT8720F) encode the core voltage value:
 168 the voltage level your processor should work with. This is hardcoded by
 169 the mainboard and/or processor itself. It is a value in volts.
 170
 171 If an alarm triggers, it will remain triggered until the hardware register
 172 is read at least once. This means that the cause for the alarm may already
 173 have disappeared! Note that in the current implementation, all hardware
 174 registers are read whenever any data is read (unless it is less than 1.5
 175 seconds since the last update). This means that you can easily miss
 176 once-only alarms.
 177
 178 Out-of-limit readings can also result in beeping, if the chip is properly
 179 wired and configured. Beeping can be enabled or disabled per sensor type
 180 (temperatures, voltages and fans.)
 181
 182 The IT87xx only updates its values each 1.5 seconds; reading it more often
 183 will do no harm, but will return 'old' values.
 184
 185 To change sensor N to a thermistor, 'echo 4 > tempN_type' where N is 1, 2,
 186 or 3. To change sensor N to a thermal diode, 'echo 3 > tempN_type'.
 187 Give 0 for unused sensor. Any other value is invalid. To configure this at
 188 startup, consult lm_sensors's /etc/sensors.conf. (4 = thermistor;
 189 3 = thermal diode)
 190
 191
 192 Fan speed control
 193 -----------------
 194
 195 The fan speed control features are limited to manual PWM mode. Automatic
 196 "Smart Guardian" mode control handling is only implemented for older chips
 197 (see below.) However if you want to go for "manual mode" just write 1 to
 198 pwmN_enable.
 199
 200 If you are only able to control the fan speed with very small PWM values,
 201 try lowering the PWM base frequency (pwm1_freq). Depending on the fan,
 202 it may give you a somewhat greater control range. The same frequency is
 203 used to drive all fan outputs, which is why pwm2_freq and pwm3_freq are
 204 read-only.
 205
 206
 207 Automatic fan speed control (old interface)
 208 -------------------------------------------
 209
 210 The driver supports the old interface to automatic fan speed control
 211 which is implemented by IT8705F chips up to revision F and IT8712F
 212 chips up to revision G.
 213
 214 This interface implements 4 temperature vs. PWM output trip points.
 215 The PWM output of trip point 4 is always the maximum value (fan running
 216 at full speed) while the PWM output of the other 3 trip points can be
 217 freely chosen. The temperature of all 4 trip points can be freely chosen.
 218 Additionally, trip point 1 has an hysteresis temperature attached, to
 219 prevent fast switching between fan on and off.
 220
 221 The chip automatically computes the PWM output value based on the input
 222 temperature, based on this simple rule: if the temperature value is
 223 between trip point N and trip point N+1 then the PWM output value is
 224 the one of trip point N. The automatic control mode is less flexible
 225 than the manual control mode, but it reacts faster, is more robust and
 226 doesn't use CPU cycles.
 227
 228 Trip points must be set properly before switching to automatic fan speed
 229 control mode. The driver will perform basic integrity checks before
 230 actually switching to automatic control mode.
 231
 232
 233 Temperature offset attributes
 234 -----------------------------
 235
 236 The driver supports temp[1-3]_offset sysfs attributes to adjust the reported
 237 temperature for thermal diodes or diode-connected thermal transistors.
 238 If a temperature sensor is configured for thermistors, the attribute values
 239 are ignored. If the thermal sensor type is Intel PECI, the temperature offset
 240 must be programmed to the critical CPU temperature.