Documentation/hwmon/lm93.rst

Source file repositories/reference/linux-study-clean/Documentation/hwmon/lm93.rst

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Documentation/hwmon/lm93.rst
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.rst
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Support Tooling And Documentation
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Documentation
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Support Tooling And Documentation: documentation
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Repository support layer: documentation, build tooling, samples, user-space helper tools, generated initramfs support, licenses, and validation utilities.

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Kernel driver lm93
==================

Supported chips:

  * National Semiconductor LM93

    Prefix 'lm93'

    Addresses scanned: I2C 0x2c-0x2e

    Datasheet: http://www.national.com/ds.cgi/LM/LM93.pdf

  * National Semiconductor LM94

    Prefix 'lm94'

    Addresses scanned: I2C 0x2c-0x2e

    Datasheet: http://www.national.com/ds.cgi/LM/LM94.pdf


Authors:
	- Mark M. Hoffman <mhoffman@lightlink.com>
	- Ported to 2.6 by Eric J. Bowersox <ericb@aspsys.com>
	- Adapted to 2.6.20 by Carsten Emde <ce@osadl.org>
	- Modified for mainline integration by Hans J. Koch <hjk@hansjkoch.de>

Module Parameters
-----------------

* init: integer
  Set to non-zero to force some initializations (default is 0).
* disable_block: integer
  A "0" allows SMBus block data transactions if the host supports them.  A "1"
  disables SMBus block data transactions.  The default is 0.
* vccp_limit_type: integer array (2)
  Configures in7 and in8 limit type, where 0 means absolute and non-zero
  means relative.  "Relative" here refers to "Dynamic Vccp Monitoring using
  VID" from the datasheet.  It greatly simplifies the interface to allow
  only one set of limits (absolute or relative) to be in operation at a
  time (even though the hardware is capable of enabling both).  There's
  not a compelling use case for enabling both at once, anyway.  The default
  is "0,0".
* vid_agtl: integer
  A "0" configures the VID pins for V(ih) = 2.1V min, V(il) = 0.8V max.
  A "1" configures the VID pins for V(ih) = 0.8V min, V(il) = 0.4V max.
  (The latter setting is referred to as AGTL+ Compatible in the datasheet.)
  I.e. this parameter controls the VID pin input thresholds; if your VID
  inputs are not working, try changing this.  The default value is "0".


Hardware Description
--------------------

(from the datasheet)

The LM93 hardware monitor has a two wire digital interface compatible with
SMBus 2.0. Using an 8-bit ADC, the LM93 measures the temperature of two remote
diode connected transistors as well as its own die and 16 power supply
voltages. To set fan speed, the LM93 has two PWM outputs that are each
controlled by up to four temperature zones. The fancontrol algorithm is lookup
table based. The LM93 includes a digital filter that can be invoked to smooth
temperature readings for better control of fan speed. The LM93 has four
tachometer inputs to measure fan speed. Limit and status registers for all
measured values are included. The LM93 builds upon the functionality of
previous motherboard management ASICs and uses some of the LM85's features
(i.e. smart tachometer mode). It also adds measurement and control support
for dynamic Vccp monitoring and PROCHOT. It is designed to monitor a dual
processor Xeon class motherboard with a minimum of external components.

Annotation

Implementation Notes