2009-04-07 10:00:30 +08:00
|
|
|
Kernel driver g760a
|
|
|
|
|
===================
|
|
|
|
|
|
|
|
|
|
Supported chips:
|
|
|
|
|
* Global Mixed-mode Technology Inc. G760A
|
|
|
|
|
Prefix: 'g760a'
|
|
|
|
|
Datasheet: Publicly available at the GMT website
|
2010-07-24 11:51:24 +08:00
|
|
|
http://www.gmt.com.tw/product/datasheet/EDS-760A.pdf
|
2009-04-07 10:00:30 +08:00
|
|
|
|
|
|
|
|
Author: Herbert Valerio Riedel <hvr@gnu.org>
|
|
|
|
|
|
|
|
|
|
Description
|
|
|
|
|
-----------
|
|
|
|
|
|
|
|
|
|
The GMT G760A Fan Speed PWM Controller is connected directly to a fan
|
|
|
|
|
and performs closed-loop control of the fan speed.
|
|
|
|
|
|
|
|
|
|
The fan speed is programmed by setting the period via 'pwm1' of two
|
|
|
|
|
consecutive speed pulses. The period is defined in terms of clock
|
|
|
|
|
cycle counts of an assumed 32kHz clock source.
|
|
|
|
|
|
|
|
|
|
Setting a period of 0 stops the fan; setting the period to 255 sets
|
|
|
|
|
fan to maximum speed.
|
|
|
|
|
|
|
|
|
|
The measured fan rotation speed returned via 'fan1_input' is derived
|
|
|
|
|
from the measured speed pulse period by assuming again a 32kHz clock
|
|
|
|
|
source and a 2 pulse-per-revolution fan.
|
|
|
|
|
|
|
|
|
|
The 'alarms' file provides access to the two alarm bits provided by
|
|
|
|
|
the G760A chip's status register: Bit 0 is set when the actual fan
|
|
|
|
|
speed differs more than 20% with respect to the programmed fan speed;
|
|
|
|
|
bit 1 is set when fan speed is below 1920 RPM.
|
|
|
|
|
|
|
|
|
|
The g760a driver will not update its values more frequently than every
|
|
|
|
|
other second; reading them more often will do no harm, but will return
|
|
|
|
|
'old' values.
|
