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-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 <ppokorny@penguincomputing.com>,
- Frodo Looijaard <frodol@dds.nl>,
- Richard Barrington <rich_b_nz@clear.net.nz>,
- Margit Schubert-While <margitsw@t-online.de>,
- Justin Thiessen <jthiessen@penguincomputing.com>
-
-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.