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diff --git a/Documentation/i2c/chips/pc87360 b/Documentation/i2c/chips/pc87360 new file mode 100644 index 000000000000..89a8fcfa78df --- /dev/null +++ b/Documentation/i2c/chips/pc87360 @@ -0,0 +1,189 @@ +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: + http://www.national.com/pf/PC/PC87360.html + http://www.national.com/pf/PC/PC87363.html + http://www.national.com/pf/PC/PC87364.html + http://www.national.com/pf/PC/PC87365.html + http://www.national.com/pf/PC/PC87366.html + +Authors: Jean Delvare <khali@linux-fr.org> + +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. |