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Frodo Looijaard
9f600e9c2c
I am trying to create a more-or-less standard documentation format for doc/chips/* files. I am not quite satisfied with the lm75 and lm78 docs yet, but it is starting to come. Basically, I want as much information in it as possible, and to generate most of it automatically. But that is harder than I though it would be. Also, a small library bugfix (class problem) and a doc-features fix. git-svn-id: http://lm-sensors.org/svn/lm-sensors/trunk@210 7894878c-1315-0410-8ee3-d5d059ff63e0
122 lines
6.1 KiB
Plaintext
122 lines
6.1 KiB
Plaintext
Kernel driver `lm78.o'
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Prefixes: lm78 (LM78, I2C and ISA)
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lm78-j (LM78-J, I2C and ISA)
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lm79 (LM79, I2C and ISA)
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This driver implements support for the National Semiconductor LM78, LM78-J
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and LM79. They are described as `Microprocessor System Hardware Monitors'.
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There is almost no difference between these three chips. Functionally, the
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LM78 and LM78-J are exactly identical. The LM79 has one more VID line,
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which is used to report the lower voltages newer Pentium processors use.
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From now on, LM7* means either of these three types.
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The LM7* implements one temperatur sensor, three FAN rotation speed sensors,
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seven voltage sensors, VID lines, alarms, and some miscellaneous stuff.
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Temperatures are measured in degrees Celcius. An alarm is triggered once
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when the Overtemperature Shutdown limit is crossed; it is triggered again
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as soon as it drops below the Hysteris value. A more useful behaviour
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can be found by setting the Hysteris value to +127 degrees Celcius; in
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this case, alarms are issued during all the time when the actual temperature \
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is above the Overtemperature Shutdown value.
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FAN rotation speeds are reported in RPM (rotations per minute). An alarm is
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triggered if the rotation speed has dropped below a programmable limit. FAN
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readings can be divided by a programmable divider (1, 2, 4 or 8) to give
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the readings more range or accuracy. This is imporatant because some FANs
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report only one 'tick' each rotation, while others report two - making
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all readings twice as high. Not all RPM values can accurately be represented,
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so some rounding is done.
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Voltage sensors (also known as IN sensors) report their values in volts.
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An alarm is triggered if the voltage has crossed a programmable minimum
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or maximum limit. Note that minimum in this case always means 'closest to
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zero'; this is important for negative voltage measurements.
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The VID lines encode the core voltage value: the voltage level your processor
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should work with. This is hardcoded by the mainboard and/or processor itself.
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It is a value in volts.
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In addition to the alarms described above, there are a couple of additional
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ones. There is a BTI alarm, which gets triggered when an external chip has
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crossed its limits. Usually, this is connected to all LM75 chips; if at
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least one crosses its limits, this bit gets set. The CHAS alarm triggers
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if your computer case is open. The FIFO alarms should never trigger; it
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indicates an internal error. The SMI_IN alarm indicates some other chip
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has triggered an SMI interrupt. As we do not use SMI interrupts at all,
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this condition usually indicates there is a problem with some other
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device.
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If an alarm triggers, it will remain triggered until the hardware register
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is read at least once. This means that the cause for the alarm may
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already have disappeared! Note that in the current implementation, all
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hardware registers are read whenever any data is read (unless it is less
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than 1.5 seconds since the last update). This means that you can easily
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miss once-only alarms.
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The LM7* only updates its values each 1.5 seconds; reading it more often
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will do no harm, but will return 'old' values.
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/proc and sysctl interface files:
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* alarms (LM78_SYSCTL_ALARMS)
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A single number (R,0) which indicates which alarms are currently
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triggered. It is a logical OR of the following bit values:
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LM78_ALARM_BTI, LM78_ALARM_CHAS, LM78_ALARM_FIFO, LM78_ALARM_SMI_IN,
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LM78_ALARMS_IN[0-6], LM78_ALARM_FAN[1-3], LM78_ALARM_TEMP
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* fan[1-3] (LM78_SYSCTL_FAN[1-3])
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The Fan Low Limit (RW,0) and Current Fan Reading (R,0).
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* fan_div (LM78_SYSCTL_FAN_DIV)
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The FAN1 Scaling Factor (RW,0), FAN2 Scaling Factor (RW,0) and FAN3 Scaling
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Factor (RW,0).
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* in[0-6] (LM78_SYSCTL_IN[0-6])
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The Voltage Low Limit (RW,2), Voltage High Limit (RW,2) and Current
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Voltage Reading (R,2).
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* temp
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The Overtemperature Shutdown Value (RW,1), Hysteris Value (RW,1) and
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Current Temperature (R,1).
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* vid
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The Core Voltage Value (R,2).
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configuration file features:
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NAME LABEL CLASS COMPUTE CLASS RW
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alarms: R
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fan1: R
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fan1_div: fan1 RW
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fan1_min: fan1 RW
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fan2: R
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fan2_div: fan2 RW
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fan2_min: fan2 RW
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fan3: R
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fan3_div: fan3 R
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fan3_min: fan3 RW
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in0: R
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in0_max: in0 in0 RW
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in0_min: in0 in0 RW
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in1: R
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in1_max: in1 in1 RW
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in1_min: in1 in1 RW
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in2: R
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in2_max: in2 in2 RW
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in2_min: in2 in2 RW
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in3: R
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in3_max: in3 in3 RW
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in3_min: in3 in3 RW
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in4: R
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in4_max: in4 in4 RW
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in4_min: in4 in4 RW
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in5: R
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in5_max: in5 in5 RW
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in5_min: in5 in5 RW
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in6: R
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in6_max: in6 in6 RW
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in6_min: in6 in6 RW
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temp: R
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temp_hyst: temp temp RW
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temp_over: temp temp RW
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vid: R
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