Documentation/hwmon/lm63.rst

Source file repositories/reference/linux-study-clean/Documentation/hwmon/lm63.rst

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Linux kernel
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Documentation/hwmon/lm63.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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Annotated Snippet

Kernel driver lm63
==================

Supported chips:

  * National Semiconductor LM63

    Prefix: 'lm63'

    Addresses scanned: I2C 0x4c

    Datasheet: Publicly available at the National Semiconductor website

	       http://www.national.com/pf/LM/LM63.html

  * National Semiconductor LM64

    Prefix: 'lm64'

    Addresses scanned: I2C 0x18 and 0x4e

    Datasheet: Publicly available at the National Semiconductor website

	       http://www.national.com/pf/LM/LM64.html

  * National Semiconductor LM96163

    Prefix: 'lm96163'

    Addresses scanned: I2C 0x4c

    Datasheet: Publicly available at the National Semiconductor website

	       http://www.national.com/pf/LM/LM96163.html


Author: Jean Delvare <jdelvare@suse.de>

Thanks go to Tyan and especially Alex Buckingham for setting up a remote
access to their S4882 test platform for this driver.

  https://www.tyan.com/

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

The LM63 is a digital temperature sensor with integrated fan monitoring
and control.

The LM63 is basically an LM86 with fan speed monitoring and control
capabilities added. It misses some of the LM86 features though:

 - No low limit for local temperature.
 - No critical limit for local temperature.
 - Critical limit for remote temperature can be changed only once. We
   will consider that the critical limit is read-only.

The datasheet isn't very clear about what the tachometer reading is.

An explanation from National Semiconductor: The two lower bits of the read
value have to be masked out. The value is still 16 bit in width.

All temperature values are given in degrees Celsius. Resolution is 1.0
degree for the local temperature, 0.125 degree for the remote temperature.

The fan speed is measured using a tachometer. Contrary to most chips which
store the value in an 8-bit register and have a selectable clock divider
to make sure that the result will fit in the register, the LM63 uses 16-bit
value for measuring the speed of the fan. It can measure fan speeds down to
83 RPM, at least in theory.

Annotation

Implementation Notes