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Merge branch 'hwmon-for-linus' of git://jdelvare.pck.nerim.net/jdelva…
…re-2.6 * 'hwmon-for-linus' of git://jdelvare.pck.nerim.net/jdelvare-2.6: (47 commits) hwmon: (adm1026) Prevent log spamming hwmon: (adm1026) Fix debug messages hwmon: (adm1029) Use mask for fan_div value hwmon: (adt7470) Add documentation hwmon: (ibmaem) Automatically load on IBM systems via DMI hwmon: (ibmpex) Automatically load on IBM systems via DMI hwmon: (w83781d) Use new style driver binding hwmon: (w83781d) Stop abusing struct i2c_client for ISA devices hwmon: (w83781d) Make ISA interface depend on CONFIG_ISA hwmon: (w83781d) Additional information about AS99127F PWM hwmon: (w83781d) Detect alias chips hwmon: (w83781d) Refactor beep enable handling hwmon: Drop dead links to old National Semiconductor chip datasheets hwmon: (w83791d) add support for thermal cruise mode hwmon: (w83791d) add pwm_enable support hwmon: (w83791d) add manual PWM support hwmon: (w83791d) fan 4/5 pins can also be used for gpio hwmon: (max1619) Use inline functions instead of macros hwmon: (it87) Fix thermal sensor type values hwmon: (lm78) Convert to a new-style i2c driver ...
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Kernel driver adt7470 | ||
===================== | ||
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Supported chips: | ||
* Analog Devices ADT7470 | ||
Prefix: 'adt7470' | ||
Addresses scanned: I2C 0x2C, 0x2E, 0x2F | ||
Datasheet: Publicly available at the Analog Devices website | ||
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Author: Darrick J. Wong | ||
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Description | ||
----------- | ||
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This driver implements support for the Analog Devices ADT7470 chip. There may | ||
be other chips that implement this interface. | ||
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The ADT7470 uses the 2-wire interface compatible with the SMBus 2.0 | ||
specification. Using an analog to digital converter it measures up to ten (10) | ||
external temperatures. It has four (4) 16-bit counters for measuring fan speed. | ||
There are four (4) PWM outputs that can be used to control fan speed. | ||
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A sophisticated control system for the PWM outputs is designed into the ADT7470 | ||
that allows fan speed to be adjusted automatically based on any of the ten | ||
temperature sensors. Each PWM output is individually adjustable and | ||
programmable. Once configured, the ADT7470 will adjust the PWM outputs in | ||
response to the measured temperatures with further host intervention. This | ||
feature can also be disabled for manual control of the PWM's. | ||
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Each of the measured inputs (temperature, fan speed) has corresponding high/low | ||
limit values. The ADT7470 will signal an ALARM if any measured value exceeds | ||
either limit. | ||
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The ADT7470 DOES NOT sample all inputs continuously. A single pin on the | ||
ADT7470 is connected to a multitude of thermal diodes, but the chip must be | ||
instructed explicitly to read the multitude of diodes. If you want to use | ||
automatic fan control mode, you must manually read any of the temperature | ||
sensors or the fan control algorithm will not run. The chip WILL NOT DO THIS | ||
AUTOMATICALLY; this must be done from userspace. This may be a bug in the chip | ||
design, given that many other AD chips take care of this. The driver will not | ||
read the registers more often than once every 5 seconds. Further, | ||
configuration data is only read once per minute. | ||
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Special Features | ||
---------------- | ||
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The ADT7470 has a 8-bit ADC and is capable of measuring temperatures with 1 | ||
degC resolution. | ||
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The Analog Devices datasheet is very detailed and describes a procedure for | ||
determining an optimal configuration for the automatic PWM control. | ||
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Configuration Notes | ||
------------------- | ||
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Besides standard interfaces driver adds the following: | ||
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* PWM Control | ||
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* pwm#_auto_point1_pwm and pwm#_auto_point1_temp and | ||
* pwm#_auto_point2_pwm and pwm#_auto_point2_temp - | ||
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point1: Set the pwm speed at a lower temperature bound. | ||
point2: Set the pwm speed at a higher temperature bound. | ||
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The ADT7470 will scale the pwm between the lower and higher pwm speed when | ||
the temperature is between the two temperature boundaries. PWM values range | ||
from 0 (off) to 255 (full speed). Fan speed will be set to maximum when the | ||
temperature sensor associated with the PWM control exceeds | ||
pwm#_auto_point2_temp. | ||
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Notes | ||
----- | ||
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As stated above, the temperature inputs must be read periodically from | ||
userspace in order for the automatic pwm algorithm to run. |
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