Kernel driver lm93
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==================
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Supported chips:
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* National Semiconductor LM93
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Prefix 'lm93'
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Addresses scanned: I2C 0x2c-0x2e
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Datasheet: http://www.national.com/ds.cgi/LM/LM93.pdf
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* National Semiconductor LM94
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Prefix 'lm94'
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Addresses scanned: I2C 0x2c-0x2e
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Datasheet: http://www.national.com/ds.cgi/LM/LM94.pdf
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Authors:
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Mark M. Hoffman <mhoffman@lightlink.com>
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Ported to 2.6 by Eric J. Bowersox <ericb@aspsys.com>
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Adapted to 2.6.20 by Carsten Emde <ce@osadl.org>
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Modified for mainline integration by Hans J. Koch <hjk@hansjkoch.de>
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Module Parameters
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-----------------
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* init: integer
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Set to non-zero to force some initializations (default is 0).
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* disable_block: integer
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A "0" allows SMBus block data transactions if the host supports them. A "1"
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disables SMBus block data transactions. The default is 0.
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* vccp_limit_type: integer array (2)
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Configures in7 and in8 limit type, where 0 means absolute and non-zero
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means relative. "Relative" here refers to "Dynamic Vccp Monitoring using
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VID" from the datasheet. It greatly simplifies the interface to allow
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only one set of limits (absolute or relative) to be in operation at a
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time (even though the hardware is capable of enabling both). There's
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not a compelling use case for enabling both at once, anyway. The default
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is "0,0".
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* vid_agtl: integer
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A "0" configures the VID pins for V(ih) = 2.1V min, V(il) = 0.8V max.
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A "1" configures the VID pins for V(ih) = 0.8V min, V(il) = 0.4V max.
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(The latter setting is referred to as AGTL+ Compatible in the datasheet.)
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I.e. this parameter controls the VID pin input thresholds; if your VID
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inputs are not working, try changing this. The default value is "0".
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Hardware Description
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--------------------
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(from the datasheet)
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The LM93 hardware monitor has a two wire digital interface compatible with
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SMBus 2.0. Using an 8-bit ADC, the LM93 measures the temperature of two remote
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diode connected transistors as well as its own die and 16 power supply
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voltages. To set fan speed, the LM93 has two PWM outputs that are each
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controlled by up to four temperature zones. The fancontrol algorithm is lookup
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table based. The LM93 includes a digital filter that can be invoked to smooth
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temperature readings for better control of fan speed. The LM93 has four
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tachometer inputs to measure fan speed. Limit and status registers for all
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measured values are included. The LM93 builds upon the functionality of
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previous motherboard management ASICs and uses some of the LM85's features
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(i.e. smart tachometer mode). It also adds measurement and control support
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for dynamic Vccp monitoring and PROCHOT. It is designed to monitor a dual
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processor Xeon class motherboard with a minimum of external components.
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LM94 is also supported in LM93 compatible mode. Extra sensors and features of
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LM94 are not supported.
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User Interface
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--------------
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#PROCHOT:
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The LM93 can monitor two #PROCHOT signals. The results are found in the
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sysfs files prochot1, prochot2, prochot1_avg, prochot2_avg, prochot1_max,
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and prochot2_max. prochot1_max and prochot2_max contain the user limits
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for #PROCHOT1 and #PROCHOT2, respectively. prochot1 and prochot2 contain
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the current readings for the most recent complete time interval. The
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value of prochot1_avg and prochot2_avg is something like a 2 period
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exponential moving average (but not quite - check the datasheet). Note
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that this third value is calculated by the chip itself. All values range
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from 0-255 where 0 indicates no throttling, and 255 indicates > 99.6%.
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The monitoring intervals for the two #PROCHOT signals is also configurable.
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These intervals can be found in the sysfs files prochot1_interval and
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prochot2_interval. The values in these files specify the intervals for
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#P1_PROCHOT and #P2_PROCHOT, respectively. Selecting a value not in this
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list will cause the driver to use the next largest interval. The available
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intervals are (in seconds):
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#PROCHOT intervals: 0.73, 1.46, 2.9, 5.8, 11.7, 23.3, 46.6, 93.2, 186, 372
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It is possible to configure the LM93 to logically short the two #PROCHOT
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signals. I.e. when #P1_PROCHOT is asserted, the LM93 will automatically
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assert #P2_PROCHOT, and vice-versa. This mode is enabled by writing a
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non-zero integer to the sysfs file prochot_short.
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The LM93 can also override the #PROCHOT pins by driving a PWM signal onto
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one or both of them. When overridden, the signal has a period of 3.56 ms,
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a minimum pulse width of 5 clocks (at 22.5kHz => 6.25% duty cycle), and
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a maximum pulse width of 80 clocks (at 22.5kHz => 99.88% duty cycle).
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The sysfs files prochot1_override and prochot2_override contain boolean
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integers which enable or disable the override function for #P1_PROCHOT and
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#P2_PROCHOT, respectively. The sysfs file prochot_override_duty_cycle
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contains a value controlling the duty cycle for the PWM signal used when
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the override function is enabled. This value ranges from 0 to 15, with 0
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indicating minimum duty cycle and 15 indicating maximum.
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#VRD_HOT:
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The LM93 can monitor two #VRD_HOT signals. The results are found in the
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sysfs files vrdhot1 and vrdhot2. There is one value per file: a boolean for
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which 1 indicates #VRD_HOT is asserted and 0 indicates it is negated. These
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files are read-only.
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Smart Tach Mode:
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(from the datasheet)
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If a fan is driven using a low-side drive PWM, the tachometer
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output of the fan is corrupted. The LM93 includes smart tachometer
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circuitry that allows an accurate tachometer reading to be
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achieved despite the signal corruption. In smart tach mode all
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four signals are measured within 4 seconds.
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Smart tach mode is enabled by the driver by writing 1 or 2 (associating the
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the fan tachometer with a pwm) to the sysfs file fan<n>_smart_tach. A zero
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will disable the function for that fan. Note that Smart tach mode cannot be
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enabled if the PWM output frequency is 22500 Hz (see below).
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Manual PWM:
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The LM93 has a fixed or override mode for the two PWM outputs (although, there
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are still some conditions that will override even this mode - see section
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15.10.6 of the datasheet for details.) The sysfs files pwm1_override
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and pwm2_override are used to enable this mode; each is a boolean integer
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where 0 disables and 1 enables the manual control mode. The sysfs files pwm1
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and pwm2 are used to set the manual duty cycle; each is an integer (0-255)
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where 0 is 0% duty cycle, and 255 is 100%. Note that the duty cycle values
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are constrained by the hardware. Selecting a value which is not available
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will cause the driver to use the next largest value. Also note: when manual
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PWM mode is disabled, the value of pwm1 and pwm2 indicates the current duty
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cycle chosen by the h/w.
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PWM Output Frequency:
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The LM93 supports several different frequencies for the PWM output channels.
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The sysfs files pwm1_freq and pwm2_freq are used to select the frequency. The
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frequency values are constrained by the hardware. Selecting a value which is
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not available will cause the driver to use the next largest value. Also note
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that this parameter has implications for the Smart Tach Mode (see above).
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PWM Output Frequencies (in Hz): 12, 36, 48, 60, 72, 84, 96, 22500 (default)
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Automatic PWM:
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The LM93 is capable of complex automatic fan control, with many different
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points of configuration. To start, each PWM output can be bound to any
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combination of eight control sources. The final PWM is the largest of all
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individual control sources to which the PWM output is bound.
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The eight control sources are: temp1-temp4 (aka "zones" in the datasheet),
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#PROCHOT 1 & 2, and #VRDHOT 1 & 2. The bindings are expressed as a bitmask
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in the sysfs files pwm<n>_auto_channels, where a "1" enables the binding, and
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a "0" disables it. The h/w default is 0x0f (all temperatures bound).
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0x01 - Temp 1
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0x02 - Temp 2
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0x04 - Temp 3
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0x08 - Temp 4
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0x10 - #PROCHOT 1
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0x20 - #PROCHOT 2
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0x40 - #VRDHOT 1
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0x80 - #VRDHOT 2
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The function y = f(x) takes a source temperature x to a PWM output y. This
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function of the LM93 is derived from a base temperature and a table of 12
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temperature offsets. The base temperature is expressed in degrees C in the
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sysfs files temp<n>_auto_base. The offsets are expressed in cumulative
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degrees C, with the value of offset <i> for temperature value <n> being
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contained in the file temp<n>_auto_offset<i>. E.g. if the base temperature
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is 40C:
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offset # temp<n>_auto_offset<i> range pwm
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1 0 - 25.00%
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2 0 - 28.57%
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3 1 40C - 41C 32.14%
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4 1 41C - 42C 35.71%
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5 2 42C - 44C 39.29%
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6 2 44C - 46C 42.86%
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7 2 48C - 50C 46.43%
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8 2 50C - 52C 50.00%
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9 2 52C - 54C 53.57%
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10 2 54C - 56C 57.14%
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11 2 56C - 58C 71.43%
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12 2 58C - 60C 85.71%
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> 60C 100.00%
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Valid offsets are in the range 0C <= x <= 7.5C in 0.5C increments.
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There is an independent base temperature for each temperature channel. Note,
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however, there are only two tables of offsets: one each for temp[12] and
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temp[34]. Therefore, any change to e.g. temp1_auto_offset<i> will also
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affect temp2_auto_offset<i>.
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The LM93 can also apply hysteresis to the offset table, to prevent unwanted
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oscillation between two steps in the offsets table. These values are found in
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the sysfs files temp<n>_auto_offset_hyst. The value in this file has the
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same representation as in temp<n>_auto_offset<i>.
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If a temperature reading falls below the base value for that channel, the LM93
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will use the minimum PWM value. These values are found in the sysfs files
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temp<n>_auto_pwm_min. Note, there are only two minimums: one each for temp[12]
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and temp[34]. Therefore, any change to e.g. temp1_auto_pwm_min will also
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affect temp2_auto_pwm_min.
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PWM Spin-Up Cycle:
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A spin-up cycle occurs when a PWM output is commanded from 0% duty cycle to
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some value > 0%. The LM93 supports a minimum duty cycle during spin-up. These
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values are found in the sysfs files pwm<n>_auto_spinup_min. The value in this
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file has the same representation as other PWM duty cycle values. The
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duration of the spin-up cycle is also configurable. These values are found in
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the sysfs files pwm<n>_auto_spinup_time. The value in this file is
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the spin-up time in seconds. The available spin-up times are constrained by
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the hardware. Selecting a value which is not available will cause the driver
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to use the next largest value.
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Spin-up Durations: 0 (disabled, h/w default), 0.1, 0.25, 0.4, 0.7, 1.0,
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2.0, 4.0
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#PROCHOT and #VRDHOT PWM Ramping:
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If the #PROCHOT or #VRDHOT signals are asserted while bound to a PWM output
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channel, the LM93 will ramp the PWM output up to 100% duty cycle in discrete
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steps. The duration of each step is configurable. There are two files, with
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one value each in seconds: pwm_auto_prochot_ramp and pwm_auto_vrdhot_ramp.
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The available ramp times are constrained by the hardware. Selecting a value
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which is not available will cause the driver to use the next largest value.
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Ramp Times: 0 (disabled, h/w default) to 0.75 in 0.05 second intervals
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Fan Boost:
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For each temperature channel, there is a boost temperature: if the channel
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exceeds this limit, the LM93 will immediately drive both PWM outputs to 100%.
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This limit is expressed in degrees C in the sysfs files temp<n>_auto_boost.
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There is also a hysteresis temperature for this function: after the boost
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limit is reached, the temperature channel must drop below this value before
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the boost function is disabled. This temperature is also expressed in degrees
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C in the sysfs files temp<n>_auto_boost_hyst.
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GPIO Pins:
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The LM93 can monitor the logic level of four dedicated GPIO pins as well as the
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four tach input pins. GPIO0-GPIO3 correspond to (fan) tach 1-4, respectively.
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All eight GPIOs are read by reading the bitmask in the sysfs file gpio. The
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LSB is GPIO0, and the MSB is GPIO7.
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LM93 Unique sysfs Files
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-----------------------
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file description
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-------------------------------------------------------------
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prochot<n> current #PROCHOT %
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prochot<n>_avg moving average #PROCHOT %
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prochot<n>_max limit #PROCHOT %
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prochot_short enable or disable logical #PROCHOT pin short
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prochot<n>_override force #PROCHOT assertion as PWM
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prochot_override_duty_cycle
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duty cycle for the PWM signal used when
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#PROCHOT is overridden
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prochot<n>_interval #PROCHOT PWM sampling interval
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vrdhot<n> 0 means negated, 1 means asserted
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fan<n>_smart_tach enable or disable smart tach mode
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pwm<n>_auto_channels select control sources for PWM outputs
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pwm<n>_auto_spinup_min minimum duty cycle during spin-up
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pwm<n>_auto_spinup_time duration of spin-up
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pwm_auto_prochot_ramp ramp time per step when #PROCHOT asserted
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pwm_auto_vrdhot_ramp ramp time per step when #VRDHOT asserted
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temp<n>_auto_base temperature channel base
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temp<n>_auto_offset[1-12]
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temperature channel offsets
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temp<n>_auto_offset_hyst
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temperature channel offset hysteresis
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temp<n>_auto_boost temperature channel boost (PWMs to 100%) limit
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temp<n>_auto_boost_hyst temperature channel boost hysteresis
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gpio input state of 8 GPIO pins; read-only
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