mirror of
https://github.com/edk2-porting/linux-next.git
synced 2024-12-22 04:03:58 +08:00
54fe4671aa
The ADT7476 has 5 dedicated pins for VID input, and the +12V input can optionally be used as a 6th VID pin. Add support for VID input. Signed-off-by: Jean Delvare <khali@linux-fr.org> Cc: Hans de Goede <hdegoede@redhat.com> Cc: Jordan Crouse <jordan@cosmicpenguin.net> Cc: "Darrick J. Wong" <djwong@us.ibm.com>
118 lines
4.2 KiB
Plaintext
118 lines
4.2 KiB
Plaintext
Kernel driver adt7475
|
|
=====================
|
|
|
|
Supported chips:
|
|
* Analog Devices ADT7473
|
|
Prefix: 'adt7473'
|
|
Addresses scanned: I2C 0x2C, 0x2D, 0x2E
|
|
Datasheet: Publicly available at the On Semiconductors website
|
|
* Analog Devices ADT7475
|
|
Prefix: 'adt7475'
|
|
Addresses scanned: I2C 0x2E
|
|
Datasheet: Publicly available at the On Semiconductors website
|
|
* Analog Devices ADT7476
|
|
Prefix: 'adt7476'
|
|
Addresses scanned: I2C 0x2C, 0x2D, 0x2E
|
|
Datasheet: Publicly available at the On Semiconductors website
|
|
* Analog Devices ADT7490
|
|
Prefix: 'adt7490'
|
|
Addresses scanned: I2C 0x2C, 0x2D, 0x2E
|
|
Datasheet: Publicly available at the On Semiconductors website
|
|
|
|
Authors:
|
|
Jordan Crouse
|
|
Hans de Goede
|
|
Darrick J. Wong (documentation)
|
|
Jean Delvare
|
|
|
|
|
|
Description
|
|
-----------
|
|
|
|
This driver implements support for the Analog Devices ADT7473, ADT7475,
|
|
ADT7476 and ADT7490 chip family. The ADT7473 and ADT7475 differ only in
|
|
minor details. The ADT7476 has additional features, including extra voltage
|
|
measurement inputs and VID support. The ADT7490 also has additional
|
|
features, including extra voltage measurement inputs and PECI support. All
|
|
the supported chips will be collectively designed by the name "ADT747x" in
|
|
the rest of this document.
|
|
|
|
The ADT747x 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) or more 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
|
|
ADT747x 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 ADT747x 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 ADT747x will signal an ALARM if
|
|
any measured value exceeds either limit.
|
|
|
|
The ADT747x 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.
|
|
|
|
Chip Differences Summary
|
|
------------------------
|
|
|
|
ADT7473:
|
|
* 2 voltage inputs
|
|
* system acoustics optimizations (not implemented)
|
|
|
|
ADT7475:
|
|
* 2 voltage inputs
|
|
|
|
ADT7476:
|
|
* 5 voltage inputs
|
|
* VID support
|
|
|
|
ADT7490:
|
|
* 6 voltage inputs
|
|
* 1 Imon input (not implemented)
|
|
* PECI support (not implemented)
|
|
* 2 GPIO pins (not implemented)
|
|
* system acoustics optimizations (not implemented)
|
|
|
|
Special Features
|
|
----------------
|
|
|
|
The ADT747x has a 10-bit ADC and can therefore measure temperatures
|
|
with a resolution of 0.25 degree Celsius. Temperature readings can be
|
|
configured either for two's complement format or "Offset 64" format,
|
|
wherein 64 is subtracted from the raw value to get the temperature value.
|
|
|
|
The datasheet is very detailed and describes a procedure for determining
|
|
an optimal configuration for the automatic PWM control.
|
|
|
|
Fan Speed Control
|
|
-----------------
|
|
|
|
The driver exposes two trip points per PWM channel.
|
|
|
|
point1: Set the PWM speed at the lower temperature bound
|
|
point2: Set the PWM speed at the higher temperature bound
|
|
|
|
The ADT747x will scale the PWM linearly between the lower and higher PWM
|
|
speed when the temperature is between the two temperature boundaries.
|
|
Temperature boundaries are associated to temperature channels rather than
|
|
PWM outputs, and a given PWM output can be controlled by several temperature
|
|
channels. As a result, the ADT747x may compute more than one PWM value
|
|
for a channel at a given time, in which case the maximum value (fastest
|
|
fan speed) is applied. PWM values range from 0 (off) to 255 (full speed).
|
|
|
|
Fan speed may 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.
|