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