73 lines
2.7 KiB
Plaintext
73 lines
2.7 KiB
Plaintext
|
Kernel driver adt7473
|
||
|
|
======================
|
||
|
|
|
||
|
|
Supported chips:
|
||
|
|
* Analog Devices ADT7473
|
||
|
|
Prefix: 'adt7473'
|
||
|
|
Addresses scanned: I2C 0x2C, 0x2D, 0x2E
|
||
|
|
Datasheet: Publicly available at the Analog Devices website
|
||
|
|
|
||
|
|
Author: Darrick J. Wong
|
||
|
|
|
||
|
|
Description
|
||
|
|
-----------
|
||
|
|
|
||
|
|
This driver implements support for the Analog Devices ADT7473 chip family.
|
||
|
|
|
||
|
|
The ADT7473 uses the 2-wire interface compatible with the SMBUS 2.0
|
||
|
|
specification. Using an analog to digital converter it measures three (3)
|
||
|
|
temperatures and two (2) voltages. It has four (4) 16-bit counters for
|
||
|
|
measuring fan speed. There are three (3) PWM outputs that can be used
|
||
|
|
to control fan speed.
|
||
|
|
|
||
|
|
A sophisticated control system for the PWM outputs is designed into the
|
||
|
|
ADT7473 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 ADT7473 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 ADT7473 will signal an ALARM if
|
||
|
|
any measured value exceeds either limit.
|
||
|
|
|
||
|
|
The ADT7473 samples all inputs continuously. The driver will not read
|
||
|
|
the registers more often than once every other second. Further,
|
||
|
|
configuration data is only read once per minute.
|
||
|
|
|
||
|
|
Special Features
|
||
|
|
----------------
|
||
|
|
|
||
|
|
The ADT7473 have a 10-bit ADC and can therefore measure temperatures
|
||
|
|
with 0.25 degC resolution. Temperature readings can be configured either
|
||
|
|
for twos complement format or "Offset 64" format, wherein 63 is subtracted
|
||
|
|
from the raw value to get the temperature value.
|
||
|
|
|
||
|
|
The Analog Devices datasheet is very detailed and describes a procedure for
|
||
|
|
determining an optimal configuration for the automatic PWM control.
|
||
|
|
|
||
|
|
Configuration Notes
|
||
|
|
-------------------
|
||
|
|
|
||
|
|
Besides standard interfaces driver adds the following:
|
||
|
|
|
||
|
|
* PWM Control
|
||
|
|
|
||
|
|
* pwm#_auto_point1_pwm and temp#_auto_point1_temp and
|
||
|
|
* pwm#_auto_point2_pwm and temp#_auto_point2_temp -
|
||
|
|
|
||
|
|
point1: Set the pwm speed at a lower temperature bound.
|
||
|
|
point2: Set the pwm speed at a higher temperature bound.
|
||
|
|
|
||
|
|
The ADT7473 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 temp#_max.
|
||
|
|
|
||
|
|
Notes
|
||
|
|
-----
|
||
|
|
|
||
|
|
The NVIDIA binary driver presents an ADT7473 chip via an on-card i2c bus.
|
||
|
|
Unfortunately, they fail to set the i2c adapter class, so this driver may
|
||
|
|
fail to find the chip until the nvidia driver is patched.
|