Documentation/hwmon/lm85 - kernel/common - Git at Google

 Kernel driver lm85
 ==================

 Supported chips:
   * National Semiconductor LM85 (B and C versions)
     Prefix: 'lm85'
     Addresses scanned: I2C 0x2c, 0x2d, 0x2e
     Datasheet: http://www.national.com/pf/LM/LM85.html
   * Analog Devices ADM1027
     Prefix: 'adm1027'
     Addresses scanned: I2C 0x2c, 0x2d, 0x2e
     Datasheet: http://www.onsemi.com/PowerSolutions/product.do?id=ADM1027
   * Analog Devices ADT7463
     Prefix: 'adt7463'
     Addresses scanned: I2C 0x2c, 0x2d, 0x2e
     Datasheet: http://www.onsemi.com/PowerSolutions/product.do?id=ADT7463
   * Analog Devices ADT7468
     Prefix: 'adt7468'
     Addresses scanned: I2C 0x2c, 0x2d, 0x2e
     Datasheet: http://www.onsemi.com/PowerSolutions/product.do?id=ADT7468
   * SMSC EMC6D100, SMSC EMC6D101
     Prefix: 'emc6d100'
     Addresses scanned: I2C 0x2c, 0x2d, 0x2e
     Datasheet: http://www.smsc.com/media/Downloads_Public/discontinued/6d100.pdf
   * SMSC EMC6D102
     Prefix: 'emc6d102'
     Addresses scanned: I2C 0x2c, 0x2d, 0x2e
     Datasheet: http://www.smsc.com/main/catalog/emc6d102.html
   * SMSC EMC6D103
     Prefix: 'emc6d103'
     Addresses scanned: I2C 0x2c, 0x2d, 0x2e
     Datasheet: http://www.smsc.com/main/catalog/emc6d103.html
   * SMSC EMC6D103S
     Prefix: 'emc6d103s'
     Addresses scanned: I2C 0x2c, 0x2d, 0x2e
     Datasheet: http://www.smsc.com/main/catalog/emc6d103s.html

 Authors:
         Philip Pokorny <[email protected]>,
         Frodo Looijaard <[email protected]>,
         Richard Barrington <[email protected]>,
         Margit Schubert-While <[email protected]>,
         Justin Thiessen <[email protected]>

 Description
 -----------

 This driver implements support for the National Semiconductor LM85 and
 compatible chips including the Analog Devices ADM1027, ADT7463, ADT7468 and
 SMSC EMC6D10x chips family.

 The LM85 uses the 2-wire interface compatible with the SMBUS 2.0
 specification. Using an analog to digital converter it measures three (3)
 temperatures and five (5) voltages. It has four (4) 16-bit counters for
 measuring fan speed. Five (5) digital inputs are provided for sampling the
 VID signals from the processor to the VRM. Lastly, there are three (3) PWM
 outputs that can be used to control fan speed.

 The voltage inputs have internal scaling resistors so that the following
 voltage can be measured without external resistors:

   2.5V, 3.3V, 5V, 12V, and CPU core voltage (2.25V)

 The temperatures measured are one internal diode, and two remote diodes.
 Remote 1 is generally the CPU temperature. These inputs are designed to
 measure a thermal diode like the one in a Pentium 4 processor in a socket
 423 or socket 478 package. They can also measure temperature using a
 transistor like the 2N3904.

 A sophisticated control system for the PWM outputs is designed into the
 LM85 that allows fan speed to be adjusted automatically based on any of the
 three temperature sensors. Each PWM output is individually adjustable and
 programmable. Once configured, the LM85 will adjust the PWM outputs in
 response to the measured temperatures without further host intervention.
 This feature can also be disabled for manual control of the PWM's.

 Each of the measured inputs (voltage, temperature, fan speed) has
 corresponding high/low limit values. The LM85 will signal an ALARM if any
 measured value exceeds either limit.

 The LM85 samples all inputs continuously. The lm85 driver will not read
 the registers more often than once a second. Further, configuration data is
 only read once each 5 minutes. There is twice as much config data as
 measurements, so this would seem to be a worthwhile optimization.

 Special Features
 ----------------

 The LM85 has four fan speed monitoring modes. The ADM1027 has only two.
 Both have special circuitry to compensate for PWM interactions with the
 TACH signal from the fans. The ADM1027 can be configured to measure the
 speed of a two wire fan, but the input conditioning circuitry is different
 for 3-wire and 2-wire mode. For this reason, the 2-wire fan modes are not
 exposed to user control. The BIOS should initialize them to the correct
 mode. If you've designed your own ADM1027, you'll have to modify the
 init_client function and add an insmod parameter to set this up.

 To smooth the response of fans to changes in temperature, the LM85 has an
 optional filter for smoothing temperatures. The ADM1027 has the same
 config option but uses it to rate limit the changes to fan speed instead.

 The ADM1027, ADT7463 and ADT7468 have a 10-bit ADC and can therefore
 measure temperatures with 0.25 degC resolution. They also provide an offset
 to the temperature readings that is automatically applied during
 measurement. This offset can be used to zero out any errors due to traces
 and placement. The documentation says that the offset is in 0.25 degC
 steps, but in initial testing of the ADM1027 it was 1.00 degC steps. Analog
 Devices has confirmed this "bug". The ADT7463 is reported to work as
 described in the documentation. The current lm85 driver does not show the
 offset register.

 The ADT7468 has a high-frequency PWM mode, where all PWM outputs are
 driven by a 22.5 kHz clock. This is a global mode, not per-PWM output,
 which means that setting any PWM frequency above 11.3 kHz will switch
 all 3 PWM outputs to a 22.5 kHz frequency. Conversely, setting any PWM
 frequency below 11.3 kHz will switch all 3 PWM outputs to a frequency
 between 10 and 100 Hz, which can then be tuned separately.

 See the vendor datasheets for more information. There is application note
 from National (AN-1260) with some additional information about the LM85.
 The Analog Devices datasheet is very detailed and describes a procedure for
 determining an optimal configuration for the automatic PWM control.

 The SMSC EMC6D100 & EMC6D101 monitor external voltages, temperatures, and
 fan speeds. They use this monitoring capability to alert the system to out
 of limit conditions and can automatically control the speeds of multiple
 fans in a PC or embedded system. The EMC6D101, available in a 24-pin SSOP
 package, and the EMC6D100, available in a 28-pin SSOP package, are designed
 to be register compatible. The EMC6D100 offers all the features of the
 EMC6D101 plus additional voltage monitoring and system control features.
 Unfortunately it is not possible to distinguish between the package
 versions on register level so these additional voltage inputs may read
 zero. EMC6D102 and EMC6D103 feature additional ADC bits thus extending precision
 of voltage and temperature channels.

 SMSC EMC6D103S is similar to EMC6D103, but does not support pwm#_auto_pwm_minctl
 and temp#_auto_temp_off.

 Hardware Configurations
 -----------------------

 The LM85 can be jumpered for 3 different SMBus addresses. There are
 no other hardware configuration options for the LM85.

 The lm85 driver detects both LM85B and LM85C revisions of the chip. See the
 datasheet for a complete description of the differences. Other than
 identifying the chip, the driver behaves no differently with regard to
 these two chips. The LM85B is recommended for new designs.

 The ADM1027, ADT7463 and ADT7468 chips have an optional SMBALERT output
 that can be used to signal the chipset in case a limit is exceeded or the
 temperature sensors fail. Individual sensor interrupts can be masked so
 they won't trigger SMBALERT. The SMBALERT output if configured replaces one
 of the other functions (PWM2 or IN0). This functionality is not implemented
 in current driver.

 The ADT7463 and ADT7468 also have an optional THERM output/input which can
 be connected to the processor PROC_HOT output. If available, the autofan
 control dynamic Tmin feature can be enabled to keep the system temperature
 within spec (just?!) with the least possible fan noise.

 Configuration Notes
 -------------------

 Besides standard interfaces driver adds following:

 * Temperatures and Zones

 Each temperature sensor is associated with a Zone. There are three
 sensors and therefore three zones (# 1, 2 and 3). Each zone has the following
 temperature configuration points:

 * temp#_auto_temp_off - temperature below which fans should be off or spinning very low.
 * temp#_auto_temp_min - temperature over which fans start to spin.
 * temp#_auto_temp_max - temperature when fans spin at full speed.
 * temp#_auto_temp_crit - temperature when all fans will run full speed.

 * PWM Control

 There are three PWM outputs. The LM85 datasheet suggests that the
 pwm3 output control both fan3 and fan4. Each PWM can be individually
 configured and assigned to a zone for its control value. Each PWM can be
 configured individually according to the following options.

 * pwm#_auto_pwm_min - this specifies the PWM value for temp#_auto_temp_off
                       temperature. (PWM value from 0 to 255)

 * pwm#_auto_pwm_minctl - this flags selects for temp#_auto_temp_off temperature
                          the behaviour of fans. Write 1 to let fans spinning at
 			 pwm#_auto_pwm_min or write 0 to let them off.

 NOTE: It has been reported that there is a bug in the LM85 that causes the flag
 to be associated with the zones not the PWMs. This contradicts all the
 published documentation. Setting pwm#_min_ctl in this case actually affects all
 PWMs controlled by zone '#'.

 * PWM Controlling Zone selection

 * pwm#_auto_channels - controls zone that is associated with PWM

 Configuration choices:

    Value     Meaning
   ------  ------------------------------------------------
       1    Controlled by Zone 1
       2    Controlled by Zone 2
       3    Controlled by Zone 3
      23    Controlled by higher temp of Zone 2 or 3
     123    Controlled by highest temp of Zone 1, 2 or 3
       0    PWM always 0%  (off)
      -1    PWM always 100%  (full on)
      -2    Manual control (write to 'pwm#' to set)

 The National LM85's have two vendor specific configuration
 features. Tach. mode and Spinup Control. For more details on these,
 see the LM85 datasheet or Application Note AN-1260. These features
 are not currently supported by the lm85 driver.

 The Analog Devices ADM1027 has several vendor specific enhancements.
 The number of pulses-per-rev of the fans can be set, Tach monitoring
 can be optimized for PWM operation, and an offset can be applied to
 the temperatures to compensate for systemic errors in the
 measurements. These features are not currently supported by the lm85
 driver.

 In addition to the ADM1027 features, the ADT7463 and ADT7468 also have
 Tmin control and THERM asserted counts. Automatic Tmin control acts to
 adjust the Tmin value to maintain the measured temperature sensor at a
 specified temperature. There isn't much documentation on this feature in
 the ADT7463 data sheet. This is not supported by current driver.
	Kernel driver lm85
	==================

	Supported chips:
	* National Semiconductor LM85 (B and C versions)
	Prefix: 'lm85'
	Addresses scanned: I2C 0x2c, 0x2d, 0x2e
	Datasheet: http://www.national.com/pf/LM/LM85.html
	* Analog Devices ADM1027
	Prefix: 'adm1027'
	Addresses scanned: I2C 0x2c, 0x2d, 0x2e
	Datasheet: http://www.onsemi.com/PowerSolutions/product.do?id=ADM1027
	* Analog Devices ADT7463
	Prefix: 'adt7463'
	Addresses scanned: I2C 0x2c, 0x2d, 0x2e
	Datasheet: http://www.onsemi.com/PowerSolutions/product.do?id=ADT7463
	* Analog Devices ADT7468
	Prefix: 'adt7468'
	Addresses scanned: I2C 0x2c, 0x2d, 0x2e
	Datasheet: http://www.onsemi.com/PowerSolutions/product.do?id=ADT7468
	* SMSC EMC6D100, SMSC EMC6D101
	Prefix: 'emc6d100'
	Addresses scanned: I2C 0x2c, 0x2d, 0x2e
	Datasheet: http://www.smsc.com/media/Downloads_Public/discontinued/6d100.pdf
	* SMSC EMC6D102
	Prefix: 'emc6d102'
	Addresses scanned: I2C 0x2c, 0x2d, 0x2e
	Datasheet: http://www.smsc.com/main/catalog/emc6d102.html
	* SMSC EMC6D103
	Prefix: 'emc6d103'
	Addresses scanned: I2C 0x2c, 0x2d, 0x2e
	Datasheet: http://www.smsc.com/main/catalog/emc6d103.html
	* SMSC EMC6D103S
	Prefix: 'emc6d103s'
	Addresses scanned: I2C 0x2c, 0x2d, 0x2e
	Datasheet: http://www.smsc.com/main/catalog/emc6d103s.html

	Authors:
	Philip Pokorny <[email protected]>,
	Frodo Looijaard <[email protected]>,
	Richard Barrington <[email protected]>,
	Margit Schubert-While <[email protected]>,
	Justin Thiessen <[email protected]>

	Description
	-----------

	This driver implements support for the National Semiconductor LM85 and
	compatible chips including the Analog Devices ADM1027, ADT7463, ADT7468 and
	SMSC EMC6D10x chips family.

	The LM85 uses the 2-wire interface compatible with the SMBUS 2.0
	specification. Using an analog to digital converter it measures three (3)
	temperatures and five (5) voltages. It has four (4) 16-bit counters for
	measuring fan speed. Five (5) digital inputs are provided for sampling the
	VID signals from the processor to the VRM. Lastly, there are three (3) PWM
	outputs that can be used to control fan speed.

	The voltage inputs have internal scaling resistors so that the following
	voltage can be measured without external resistors:

	2.5V, 3.3V, 5V, 12V, and CPU core voltage (2.25V)

	The temperatures measured are one internal diode, and two remote diodes.
	Remote 1 is generally the CPU temperature. These inputs are designed to
	measure a thermal diode like the one in a Pentium 4 processor in a socket
	423 or socket 478 package. They can also measure temperature using a
	transistor like the 2N3904.

	A sophisticated control system for the PWM outputs is designed into the
	LM85 that allows fan speed to be adjusted automatically based on any of the
	three temperature sensors. Each PWM output is individually adjustable and
	programmable. Once configured, the LM85 will adjust the PWM outputs in
	response to the measured temperatures without further host intervention.
	This feature can also be disabled for manual control of the PWM's.

	Each of the measured inputs (voltage, temperature, fan speed) has
	corresponding high/low limit values. The LM85 will signal an ALARM if any
	measured value exceeds either limit.

	The LM85 samples all inputs continuously. The lm85 driver will not read
	the registers more often than once a second. Further, configuration data is
	only read once each 5 minutes. There is twice as much config data as
	measurements, so this would seem to be a worthwhile optimization.

	Special Features
	----------------

	The LM85 has four fan speed monitoring modes. The ADM1027 has only two.
	Both have special circuitry to compensate for PWM interactions with the
	TACH signal from the fans. The ADM1027 can be configured to measure the
	speed of a two wire fan, but the input conditioning circuitry is different
	for 3-wire and 2-wire mode. For this reason, the 2-wire fan modes are not
	exposed to user control. The BIOS should initialize them to the correct
	mode. If you've designed your own ADM1027, you'll have to modify the
	init_client function and add an insmod parameter to set this up.

	To smooth the response of fans to changes in temperature, the LM85 has an
	optional filter for smoothing temperatures. The ADM1027 has the same
	config option but uses it to rate limit the changes to fan speed instead.

	The ADM1027, ADT7463 and ADT7468 have a 10-bit ADC and can therefore
	measure temperatures with 0.25 degC resolution. They also provide an offset
	to the temperature readings that is automatically applied during
	measurement. This offset can be used to zero out any errors due to traces
	and placement. The documentation says that the offset is in 0.25 degC
	steps, but in initial testing of the ADM1027 it was 1.00 degC steps. Analog
	Devices has confirmed this "bug". The ADT7463 is reported to work as
	described in the documentation. The current lm85 driver does not show the
	offset register.

	The ADT7468 has a high-frequency PWM mode, where all PWM outputs are
	driven by a 22.5 kHz clock. This is a global mode, not per-PWM output,
	which means that setting any PWM frequency above 11.3 kHz will switch
	all 3 PWM outputs to a 22.5 kHz frequency. Conversely, setting any PWM
	frequency below 11.3 kHz will switch all 3 PWM outputs to a frequency
	between 10 and 100 Hz, which can then be tuned separately.

	See the vendor datasheets for more information. There is application note
	from National (AN-1260) with some additional information about the LM85.
	The Analog Devices datasheet is very detailed and describes a procedure for
	determining an optimal configuration for the automatic PWM control.

	The SMSC EMC6D100 & EMC6D101 monitor external voltages, temperatures, and
	fan speeds. They use this monitoring capability to alert the system to out
	of limit conditions and can automatically control the speeds of multiple
	fans in a PC or embedded system. The EMC6D101, available in a 24-pin SSOP
	package, and the EMC6D100, available in a 28-pin SSOP package, are designed
	to be register compatible. The EMC6D100 offers all the features of the
	EMC6D101 plus additional voltage monitoring and system control features.
	Unfortunately it is not possible to distinguish between the package
	versions on register level so these additional voltage inputs may read
	zero. EMC6D102 and EMC6D103 feature additional ADC bits thus extending precision
	of voltage and temperature channels.

	SMSC EMC6D103S is similar to EMC6D103, but does not support pwm#_auto_pwm_minctl
	and temp#_auto_temp_off.

	Hardware Configurations
	-----------------------

	The LM85 can be jumpered for 3 different SMBus addresses. There are
	no other hardware configuration options for the LM85.

	The lm85 driver detects both LM85B and LM85C revisions of the chip. See the
	datasheet for a complete description of the differences. Other than
	identifying the chip, the driver behaves no differently with regard to
	these two chips. The LM85B is recommended for new designs.

	The ADM1027, ADT7463 and ADT7468 chips have an optional SMBALERT output
	that can be used to signal the chipset in case a limit is exceeded or the
	temperature sensors fail. Individual sensor interrupts can be masked so
	they won't trigger SMBALERT. The SMBALERT output if configured replaces one
	of the other functions (PWM2 or IN0). This functionality is not implemented
	in current driver.

	The ADT7463 and ADT7468 also have an optional THERM output/input which can
	be connected to the processor PROC_HOT output. If available, the autofan
	control dynamic Tmin feature can be enabled to keep the system temperature
	within spec (just?!) with the least possible fan noise.

	Configuration Notes
	-------------------

	Besides standard interfaces driver adds following:

	* Temperatures and Zones

	Each temperature sensor is associated with a Zone. There are three
	sensors and therefore three zones (# 1, 2 and 3). Each zone has the following
	temperature configuration points:

	* temp#_auto_temp_off - temperature below which fans should be off or spinning very low.
	* temp#_auto_temp_min - temperature over which fans start to spin.
	* temp#_auto_temp_max - temperature when fans spin at full speed.
	* temp#_auto_temp_crit - temperature when all fans will run full speed.

	* PWM Control

	There are three PWM outputs. The LM85 datasheet suggests that the
	pwm3 output control both fan3 and fan4. Each PWM can be individually
	configured and assigned to a zone for its control value. Each PWM can be
	configured individually according to the following options.

	* pwm#_auto_pwm_min - this specifies the PWM value for temp#_auto_temp_off
	temperature. (PWM value from 0 to 255)

	* pwm#_auto_pwm_minctl - this flags selects for temp#_auto_temp_off temperature
	the behaviour of fans. Write 1 to let fans spinning at
	pwm#_auto_pwm_min or write 0 to let them off.

	NOTE: It has been reported that there is a bug in the LM85 that causes the flag
	to be associated with the zones not the PWMs. This contradicts all the
	published documentation. Setting pwm#_min_ctl in this case actually affects all
	PWMs controlled by zone '#'.

	* PWM Controlling Zone selection

	* pwm#_auto_channels - controls zone that is associated with PWM

	Configuration choices:

	Value Meaning
	------ ------------------------------------------------
	1 Controlled by Zone 1
	2 Controlled by Zone 2
	3 Controlled by Zone 3
	23 Controlled by higher temp of Zone 2 or 3
	123 Controlled by highest temp of Zone 1, 2 or 3
	0 PWM always 0% (off)
	-1 PWM always 100% (full on)
	-2 Manual control (write to 'pwm#' to set)

	The National LM85's have two vendor specific configuration
	features. Tach. mode and Spinup Control. For more details on these,
	see the LM85 datasheet or Application Note AN-1260. These features
	are not currently supported by the lm85 driver.

	The Analog Devices ADM1027 has several vendor specific enhancements.
	The number of pulses-per-rev of the fans can be set, Tach monitoring
	can be optimized for PWM operation, and an offset can be applied to
	the temperatures to compensate for systemic errors in the
	measurements. These features are not currently supported by the lm85
	driver.

	In addition to the ADM1027 features, the ADT7463 and ADT7468 also have
	Tmin control and THERM asserted counts. Automatic Tmin control acts to
	adjust the Tmin value to maintain the measured temperature sensor at a
	specified temperature. There isn't much documentation on this feature in
	the ADT7463 data sheet. This is not supported by current driver.