Documentation/hwmon/pc87360 - kernel/msm - Gitiles

 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 <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.
	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 <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.