mirror of
https://github.com/edk2-porting/linux-next.git
synced 2024-12-27 14:43:58 +08:00
68 lines
2.5 KiB
Plaintext
68 lines
2.5 KiB
Plaintext
|
Kernel driver adt7462
|
||
|
|
======================
|
||
|
|
|
||
|
|
Supported chips:
|
||
|
|
* Analog Devices ADT7462
|
||
|
|
Prefix: 'adt7462'
|
||
|
|
Addresses scanned: I2C 0x58, 0x5C
|
||
|
|
Datasheet: Publicly available at the Analog Devices website
|
||
|
|
|
||
|
|
Author: Darrick J. Wong
|
||
|
|
|
||
|
|
Description
|
||
|
|
-----------
|
||
|
|
|
||
|
|
This driver implements support for the Analog Devices ADT7462 chip family.
|
||
|
|
|
||
|
|
This chip is a bit of a beast. It has 8 counters for measuring fan speed. It
|
||
|
|
can also measure 13 voltages or 4 temperatures, or various combinations of the
|
||
|
|
two. See the chip documentation for more details about the exact set of
|
||
|
|
configurations. This driver does not allow one to configure the chip; that is
|
||
|
|
left to the system designer.
|
||
|
|
|
||
|
|
A sophisticated control system for the PWM outputs is designed into the ADT7462
|
||
|
|
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 ADT7462 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 ADT7462 will signal an ALARM if
|
||
|
|
any measured value exceeds either limit.
|
||
|
|
|
||
|
|
The ADT7462 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 ADT7462 have a 10-bit ADC and can therefore measure temperatures
|
||
|
|
with 0.25 degC resolution.
|
||
|
|
|
||
|
|
The Analog Devices datasheet is very detailed and describes a procedure for
|
||
|
|
determining an optimal configuration for the automatic PWM control.
|
||
|
|
|
||
|
|
The driver will report sensor labels when it is able to determine that
|
||
|
|
information from the configuration registers.
|
||
|
|
|
||
|
|
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 ADT7462 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.
|
||
|
|
|