199 lines
7.8 KiB
ReStructuredText
199 lines
7.8 KiB
ReStructuredText
Kernel driver pc87360
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=====================
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Supported chips:
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* National Semiconductor PC87360, PC87363, PC87364, PC87365 and PC87366
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Prefixes: 'pc87360', 'pc87363', 'pc87364', 'pc87365', 'pc87366'
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Addresses scanned: none, address read from Super I/O config space
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Datasheets: No longer available
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Authors: Jean Delvare <jdelvare@suse.de>
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Thanks to Sandeep Mehta, Tonko de Rooy and Daniel Ceregatti for testing.
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Thanks to Rudolf Marek for helping me investigate conversion issues.
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Module Parameters
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-----------------
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* init int
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Chip initialization level:
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- 0: None
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- **1**: Forcibly enable internal voltage and temperature channels,
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except in9
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- 2: Forcibly enable all voltage and temperature channels, except in9
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- 3: Forcibly enable all voltage and temperature channels, including in9
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Note that this parameter has no effect for the PC87360, PC87363 and PC87364
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chips.
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Also note that for the PC87366, initialization levels 2 and 3 don't enable
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all temperature channels, because some of them share pins with each other,
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so they can't be used at the same time.
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Description
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-----------
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The National Semiconductor PC87360 Super I/O chip contains monitoring and
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PWM control circuitry for two fans. The PC87363 chip is similar, and the
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PC87364 chip has monitoring and PWM control for a third fan.
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The National Semiconductor PC87365 and PC87366 Super I/O chips are complete
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hardware monitoring chipsets, not only controlling and monitoring three fans,
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but also monitoring eleven voltage inputs and two (PC87365) or up to four
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(PC87366) temperatures.
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=========== ======= ======= ======= ======= =====
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Chip #vin #fan #pwm #temp devid
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=========== ======= ======= ======= ======= =====
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PC87360 - 2 2 - 0xE1
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PC87363 - 2 2 - 0xE8
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PC87364 - 3 3 - 0xE4
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PC87365 11 3 3 2 0xE5
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PC87366 11 3 3 3-4 0xE9
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=========== ======= ======= ======= ======= =====
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The driver assumes that no more than one chip is present, and one of the
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standard Super I/O addresses is used (0x2E/0x2F or 0x4E/0x4F)
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Fan Monitoring
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--------------
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Fan rotation speeds are reported in RPM (revolutions per minute). An alarm
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is triggered if the rotation speed has dropped below a programmable limit.
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A different alarm is triggered if the fan speed is too low to be measured.
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Fan readings are affected by a programmable clock divider, giving the
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readings more range or accuracy. Usually, users have to learn how it works,
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but this driver implements dynamic clock divider selection, so you don't
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have to care no more.
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For reference, here are a few values about clock dividers:
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=========== =============== =============== ===========
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slowest accuracy highest
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measurable around 3000 accurate
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divider speed (RPM) RPM (RPM) speed (RPM)
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=========== =============== =============== ===========
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1 1882 18 6928
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2 941 37 4898
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4 470 74 3464
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8 235 150 2449
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=========== =============== =============== ===========
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For the curious, here is how the values above were computed:
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* slowest measurable speed: clock/(255*divider)
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* accuracy around 3000 RPM: 3000^2/clock
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* highest accurate speed: sqrt(clock*100)
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The clock speed for the PC87360 family is 480 kHz. I arbitrarily chose 100
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RPM as the lowest acceptable accuracy.
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As mentioned above, you don't have to care about this no more.
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Note that not all RPM values can be represented, even when the best clock
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divider is selected. This is not only true for the measured speeds, but
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also for the programmable low limits, so don't be surprised if you try to
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set, say, fan1_min to 2900 and it finally reads 2909.
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Fan Control
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-----------
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PWM (pulse width modulation) values range from 0 to 255, with 0 meaning
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that the fan is stopped, and 255 meaning that the fan goes at full speed.
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Be extremely careful when changing PWM values. Low PWM values, even
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non-zero, can stop the fan, which may cause irreversible damage to your
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hardware if temperature increases too much. When changing PWM values, go
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step by step and keep an eye on temperatures.
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One user reported problems with PWM. Changing PWM values would break fan
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speed readings. No explanation nor fix could be found.
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Temperature Monitoring
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----------------------
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Temperatures are reported in degrees Celsius. Each temperature measured has
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associated low, high and overtemperature limits, each of which triggers an
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alarm when crossed.
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The first two temperature channels are external. The third one (PC87366
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only) is internal.
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The PC87366 has three additional temperature channels, based on
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thermistors (as opposed to thermal diodes for the first three temperature
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channels). For technical reasons, these channels are held by the VLM
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(voltage level monitor) logical device, not the TMS (temperature
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measurement) one. As a consequence, these temperatures are exported as
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voltages, and converted into temperatures in user-space.
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Note that these three additional channels share their pins with the
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external thermal diode channels, so you (physically) can't use them all at
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the same time. Although it should be possible to mix the two sensor types,
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the documents from National Semiconductor suggest that motherboard
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manufacturers should choose one type and stick to it. So you will more
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likely have either channels 1 to 3 (thermal diodes) or 3 to 6 (internal
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thermal diode, and thermistors).
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Voltage Monitoring
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------------------
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Voltages are reported relatively to a reference voltage, either internal or
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external. Some of them (in7:Vsb, in8:Vdd and in10:AVdd) are divided by two
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internally, you will have to compensate in sensors.conf. Others (in0 to in6)
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are likely to be divided externally. The meaning of each of these inputs as
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well as the values of the resistors used for division is left to the
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motherboard manufacturers, so you will have to document yourself and edit
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sensors.conf accordingly. National Semiconductor has a document with
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recommended resistor values for some voltages, but this still leaves much
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room for per motherboard specificities, unfortunately. Even worse,
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motherboard manufacturers don't seem to care about National Semiconductor's
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recommendations.
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Each voltage measured has associated low and high limits, each of which
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triggers an alarm when crossed.
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When available, VID inputs are used to provide the nominal CPU Core voltage.
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The driver will default to VRM 9.0, but this can be changed from user-space.
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The chipsets can handle two sets of VID inputs (on dual-CPU systems), but
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the driver will only export one for now. This may change later if there is
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a need.
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General Remarks
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---------------
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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 already
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have disappeared! Note that all hardware registers are read whenever any
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data is read (unless it is less than 2 seconds since the last update, in
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which case cached values are returned instead). As a consequence, when
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a once-only alarm triggers, it may take 2 seconds for it to show, and 2
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more seconds for it to disappear.
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Monitoring of in9 isn't enabled at lower init levels (<3) because that
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channel measures the battery voltage (Vbat). It is a known fact that
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repeatedly sampling the battery voltage reduces its lifetime. National
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Semiconductor smartly designed their chipset so that in9 is sampled only
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once every 1024 sampling cycles (that is every 34 minutes at the default
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sampling rate), so the effect is attenuated, but still present.
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Limitations
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-----------
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The datasheets suggests that some values (fan mins, fan dividers)
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shouldn't be changed once the monitoring has started, but we ignore that
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recommendation. We'll reconsider if it actually causes trouble.
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