1Kernel driver lm93
   4Supported chips:
   5  * National Semiconductor LM93
   6    Prefix 'lm93'
   7    Addresses scanned: I2C 0x2c-0x2e
   8    Datasheet:
   9  * National Semiconductor LM94
  10    Prefix 'lm94'
  11    Addresses scanned: I2C 0x2c-0x2e
  12    Datasheet:
  15        Mark M. Hoffman <>
  16        Ported to 2.6 by Eric J. Bowersox <>
  17        Adapted to 2.6.20 by Carsten Emde <>
  18        Modified for mainline integration by Hans J. Koch <>
  20Module Parameters
  23* init: integer
  24  Set to non-zero to force some initializations (default is 0).
  25* disable_block: integer
  26  A "0" allows SMBus block data transactions if the host supports them.  A "1"
  27  disables SMBus block data transactions.  The default is 0.
  28* vccp_limit_type: integer array (2)
  29  Configures in7 and in8 limit type, where 0 means absolute and non-zero
  30  means relative.  "Relative" here refers to "Dynamic Vccp Monitoring using
  31  VID" from the datasheet.  It greatly simplifies the interface to allow
  32  only one set of limits (absolute or relative) to be in operation at a
  33  time (even though the hardware is capable of enabling both).  There's
  34  not a compelling use case for enabling both at once, anyway.  The default
  35  is "0,0".
  36* vid_agtl: integer
  37  A "0" configures the VID pins for V(ih) = 2.1V min, V(il) = 0.8V max.
  38  A "1" configures the VID pins for V(ih) = 0.8V min, V(il) = 0.4V max.
  39  (The latter setting is referred to as AGTL+ Compatible in the datasheet.)
  40  I.e. this parameter controls the VID pin input thresholds; if your VID
  41  inputs are not working, try changing this.  The default value is "0".
  44Hardware Description
  47(from the datasheet)
  49The LM93 hardware monitor has a two wire digital interface compatible with
  50SMBus 2.0. Using an 8-bit ADC, the LM93 measures the temperature of two remote
  51diode connected transistors as well as its own die and 16 power supply
  52voltages. To set fan speed, the LM93 has two PWM outputs that are each
  53controlled by up to four temperature zones. The fancontrol algorithm is lookup
  54table based. The LM93 includes a digital filter that can be invoked to smooth
  55temperature readings for better control of fan speed. The LM93 has four
  56tachometer inputs to measure fan speed. Limit and status registers for all
  57measured values are included. The LM93 builds upon the functionality of
  58previous motherboard management ASICs and uses some of the LM85's features
  59(i.e. smart tachometer mode). It also adds measurement and control support
  60for dynamic Vccp monitoring and PROCHOT. It is designed to monitor a dual
  61processor Xeon class motherboard with a minimum of external components.
  63LM94 is also supported in LM93 compatible mode. Extra sensors and features of
  64LM94 are not supported.
  67User Interface
  72The LM93 can monitor two #PROCHOT signals.  The results are found in the
  73sysfs files prochot1, prochot2, prochot1_avg, prochot2_avg, prochot1_max,
  74and prochot2_max.  prochot1_max and prochot2_max contain the user limits
  75for #PROCHOT1 and #PROCHOT2, respectively.  prochot1 and prochot2 contain
  76the current readings for the most recent complete time interval.  The
  77value of prochot1_avg and prochot2_avg is something like a 2 period
  78exponential moving average (but not quite - check the datasheet). Note
  79that this third value is calculated by the chip itself.  All values range
  80from 0-255 where 0 indicates no throttling, and 255 indicates > 99.6%.
  82The monitoring intervals for the two #PROCHOT signals is also configurable.
  83These intervals can be found in the sysfs files prochot1_interval and
  84prochot2_interval.  The values in these files specify the intervals for
  85#P1_PROCHOT and #P2_PROCHOT, respectively.  Selecting a value not in this
  86list will cause the driver to use the next largest interval.  The available
  87intervals are (in seconds):
  89#PROCHOT intervals: 0.73, 1.46, 2.9, 5.8, 11.7, 23.3, 46.6, 93.2, 186, 372
  91It is possible to configure the LM93 to logically short the two #PROCHOT
  92signals.  I.e. when #P1_PROCHOT is asserted, the LM93 will automatically
  93assert #P2_PROCHOT, and vice-versa.  This mode is enabled by writing a
  94non-zero integer to the sysfs file prochot_short.
  96The LM93 can also override the #PROCHOT pins by driving a PWM signal onto
  97one or both of them.  When overridden, the signal has a period of 3.56 ms,
  98a minimum pulse width of 5 clocks (at 22.5kHz => 6.25% duty cycle), and
  99a maximum pulse width of 80 clocks (at 22.5kHz => 99.88% duty cycle).
 101The sysfs files prochot1_override and prochot2_override contain boolean
 102integers which enable or disable the override function for #P1_PROCHOT and
 103#P2_PROCHOT, respectively.  The sysfs file prochot_override_duty_cycle
 104contains a value controlling the duty cycle for the PWM signal used when
 105the override function is enabled.  This value ranges from 0 to 15, with 0
 106indicating minimum duty cycle and 15 indicating maximum.
 110The LM93 can monitor two #VRD_HOT signals. The results are found in the
 111sysfs files vrdhot1 and vrdhot2. There is one value per file: a boolean for
 112which 1 indicates #VRD_HOT is asserted and 0 indicates it is negated. These
 113files are read-only.
 115Smart Tach Mode:
 117(from the datasheet)
 119        If a fan is driven using a low-side drive PWM, the tachometer
 120        output of the fan is corrupted. The LM93 includes smart tachometer
 121        circuitry that allows an accurate tachometer reading to be
 122        achieved despite the signal corruption.  In smart tach mode all
 123        four signals are measured within 4 seconds.
 125Smart tach mode is enabled by the driver by writing 1 or 2 (associating the
 126the fan tachometer with a pwm) to the sysfs file fan<n>_smart_tach.  A zero
 127will disable the function for that fan.  Note that Smart tach mode cannot be
 128enabled if the PWM output frequency is 22500 Hz (see below).
 130Manual PWM:
 132The LM93 has a fixed or override mode for the two PWM outputs (although, there
 133are still some conditions that will override even this mode - see section
 13415.10.6 of the datasheet for details.)  The sysfs files pwm1_override
 135and pwm2_override are used to enable this mode; each is a boolean integer
 136where 0 disables and 1 enables the manual control mode.  The sysfs files pwm1
 137and pwm2 are used to set the manual duty cycle; each is an integer (0-255)
 138where 0 is 0% duty cycle, and 255 is 100%.  Note that the duty cycle values
 139are constrained by the hardware. Selecting a value which is not available
 140will cause the driver to use the next largest value.  Also note: when manual
 141PWM mode is disabled, the value of pwm1 and pwm2 indicates the current duty
 142cycle chosen by the h/w.
 144PWM Output Frequency:
 146The LM93 supports several different frequencies for the PWM output channels.
 147The sysfs files pwm1_freq and pwm2_freq are used to select the frequency. The
 148frequency values are constrained by the hardware.  Selecting a value which is
 149not available will cause the driver to use the next largest value.  Also note
 150that this parameter has implications for the Smart Tach Mode (see above).
 152PWM Output Frequencies (in Hz): 12, 36, 48, 60, 72, 84, 96, 22500 (default)
 154Automatic PWM:
 156The LM93 is capable of complex automatic fan control, with many different
 157points of configuration.  To start, each PWM output can be bound to any
 158combination of eight control sources.  The final PWM is the largest of all
 159individual control sources to which the PWM output is bound.
 161The eight control sources are: temp1-temp4 (aka "zones" in the datasheet),
 162#PROCHOT 1 & 2, and #VRDHOT 1 & 2.  The bindings are expressed as a bitmask
 163in the sysfs files pwm<n>_auto_channels, where a "1" enables the binding, and
 164a "0" disables it. The h/w default is 0x0f (all temperatures bound).
 166        0x01 - Temp 1
 167        0x02 - Temp 2
 168        0x04 - Temp 3
 169        0x08 - Temp 4
 170        0x10 - #PROCHOT 1
 171        0x20 - #PROCHOT 2
 172        0x40 - #VRDHOT 1
 173        0x80 - #VRDHOT 2
 175The function y = f(x) takes a source temperature x to a PWM output y.  This
 176function of the LM93 is derived from a base temperature and a table of 12
 177temperature offsets.  The base temperature is expressed in degrees C in the
 178sysfs files temp<n>_auto_base.  The offsets are expressed in cumulative
 179degrees C, with the value of offset <i> for temperature value <n> being
 180contained in the file temp<n>_auto_offset<i>.  E.g. if the base temperature
 181is 40C:
 183     offset #   temp<n>_auto_offset<i>  range           pwm
 184         1              0               -                25.00%
 185         2              0               -                28.57%
 186         3              1               40C - 41C        32.14%
 187         4              1               41C - 42C        35.71%
 188         5              2               42C - 44C        39.29%
 189         6              2               44C - 46C        42.86%
 190         7              2               48C - 50C        46.43%
 191         8              2               50C - 52C        50.00%
 192         9              2               52C - 54C        53.57%
 193        10              2               54C - 56C        57.14%
 194        11              2               56C - 58C        71.43%
 195        12              2               58C - 60C        85.71%
 196                                        > 60C           100.00%
 198Valid offsets are in the range 0C <= x <= 7.5C in 0.5C increments.
 200There is an independent base temperature for each temperature channel. Note,
 201however, there are only two tables of offsets: one each for temp[12] and
 202temp[34].  Therefore, any change to e.g. temp1_auto_offset<i> will also
 203affect temp2_auto_offset<i>.
 205The LM93 can also apply hysteresis to the offset table, to prevent unwanted
 206oscillation between two steps in the offsets table.  These values are found in
 207the sysfs files temp<n>_auto_offset_hyst.  The value in this file has the
 208same representation as in temp<n>_auto_offset<i>.
 210If a temperature reading falls below the base value for that channel, the LM93
 211will use the minimum PWM value.  These values are found in the sysfs files
 212temp<n>_auto_pwm_min.  Note, there are only two minimums: one each for temp[12]
 213and temp[34].  Therefore, any change to e.g. temp1_auto_pwm_min will also
 214affect temp2_auto_pwm_min.
 216PWM Spin-Up Cycle:
 218A spin-up cycle occurs when a PWM output is commanded from 0% duty cycle to
 219some value > 0%.  The LM93 supports a minimum duty cycle during spin-up.  These
 220values are found in the sysfs files pwm<n>_auto_spinup_min. The value in this
 221file has the same representation as other PWM duty cycle values. The
 222duration of the spin-up cycle is also configurable.  These values are found in
 223the sysfs files pwm<n>_auto_spinup_time. The value in this file is
 224the spin-up time in seconds.  The available spin-up times are constrained by
 225the hardware.  Selecting a value which is not available will cause the driver
 226to use the next largest value.
 228Spin-up Durations: 0 (disabled, h/w default), 0.1, 0.25, 0.4, 0.7, 1.0,
 229                   2.0, 4.0
 231#PROCHOT and #VRDHOT PWM Ramping:
 233If the #PROCHOT or #VRDHOT signals are asserted while bound to a PWM output
 234channel, the LM93 will ramp the PWM output up to 100% duty cycle in discrete
 235steps. The duration of each step is configurable. There are two files, with
 236one value each in seconds: pwm_auto_prochot_ramp and pwm_auto_vrdhot_ramp.
 237The available ramp times are constrained by the hardware.  Selecting a value
 238which is not available will cause the driver to use the next largest value.
 240Ramp Times: 0 (disabled, h/w default) to 0.75 in 0.05 second intervals
 242Fan Boost:
 244For each temperature channel, there is a boost temperature: if the channel
 245exceeds this limit, the LM93 will immediately drive both PWM outputs to 100%.
 246This limit is expressed in degrees C in the sysfs files temp<n>_auto_boost.
 247There is also a hysteresis temperature for this function: after the boost
 248limit is reached, the temperature channel must drop below this value before
 249the boost function is disabled.  This temperature is also expressed in degrees
 250C in the sysfs files temp<n>_auto_boost_hyst.
 252GPIO Pins:
 254The LM93 can monitor the logic level of four dedicated GPIO pins as well as the
 255four tach input pins.  GPIO0-GPIO3 correspond to (fan) tach 1-4, respectively.
 256All eight GPIOs are read by reading the bitmask in the sysfs file gpio.  The
 257LSB is GPIO0, and the MSB is GPIO7.
 260LM93 Unique sysfs Files
 263        file                    description
 264        -------------------------------------------------------------
 266        prochot<n>              current #PROCHOT %
 268        prochot<n>_avg          moving average #PROCHOT %
 270        prochot<n>_max          limit #PROCHOT %
 272        prochot_short           enable or disable logical #PROCHOT pin short
 274        prochot<n>_override     force #PROCHOT assertion as PWM
 276        prochot_override_duty_cycle
 277                                duty cycle for the PWM signal used when
 278                                #PROCHOT is overridden
 280        prochot<n>_interval     #PROCHOT PWM sampling interval
 282        vrdhot<n>               0 means negated, 1 means asserted
 284        fan<n>_smart_tach       enable or disable smart tach mode
 286        pwm<n>_auto_channels    select control sources for PWM outputs
 288        pwm<n>_auto_spinup_min  minimum duty cycle during spin-up
 290        pwm<n>_auto_spinup_time duration of spin-up
 292        pwm_auto_prochot_ramp   ramp time per step when #PROCHOT asserted
 294        pwm_auto_vrdhot_ramp    ramp time per step when #VRDHOT asserted
 296        temp<n>_auto_base       temperature channel base
 298        temp<n>_auto_offset[1-12]
 299                                temperature channel offsets
 301        temp<n>_auto_offset_hyst
 302                                temperature channel offset hysteresis
 304        temp<n>_auto_boost      temperature channel boost (PWMs to 100%) limit
 306        temp<n>_auto_boost_hyst temperature channel boost hysteresis
 308        gpio                    input state of 8 GPIO pins; read-only
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