You can not select more than 25 topics
Topics must start with a letter or number, can include dashes ('-') and can be up to 35 characters long.
53 lines
2.0 KiB
53 lines
2.0 KiB
Kernel driver nsa320_hwmon
|
|
==========================
|
|
|
|
Supported chips:
|
|
* Holtek HT46R065 microcontroller with onboard firmware that configures
|
|
it to act as a hardware monitor.
|
|
Prefix: 'nsa320'
|
|
Addresses scanned: none
|
|
Datasheet: Not available, driver was reverse engineered based upon the
|
|
Zyxel kernel source
|
|
|
|
Author:
|
|
Adam Baker <linux@baker-net.org.uk>
|
|
|
|
Description
|
|
-----------
|
|
|
|
This chip is known to be used in the Zyxel NSA320 and NSA325 NAS Units and
|
|
also in some variants of the NSA310 but the driver has only been tested
|
|
on the NSA320. In all of these devices it is connected to the same 3 GPIO
|
|
lines which are used to provide chip select, clock and data lines. The
|
|
interface behaves similarly to SPI but at much lower speeds than are normally
|
|
used for SPI.
|
|
|
|
Following each chip select pulse the chip will generate a single 32 bit word
|
|
that contains 0x55 as a marker to indicate that data is being read correctly,
|
|
followed by an 8 bit fan speed in 100s of RPM and a 16 bit temperature in
|
|
tenths of a degree.
|
|
|
|
|
|
sysfs-Interface
|
|
---------------
|
|
|
|
temp1_input - temperature input
|
|
fan1_input - fan speed
|
|
|
|
Notes
|
|
-----
|
|
|
|
The access timings used in the driver are the same as used in the Zyxel
|
|
provided kernel. Testing has shown that if the delay between chip select and
|
|
the first clock pulse is reduced from 100 ms to just under 10ms then the chip
|
|
will not produce any output. If the duration of either phase of the clock
|
|
is reduced from 100 us to less than 15 us then data pulses are likely to be
|
|
read twice corrupting the output. The above analysis is based upon a sample
|
|
of one unit but suggests that the Zyxel provided delay values include a
|
|
reasonable tolerance.
|
|
|
|
The driver incorporates a limit that it will not check for updated values
|
|
faster than once a second. This is because the hardware takes a relatively long
|
|
time to read the data from the device and when it does it reads both temp and
|
|
fan speed. As the most likely case for two accesses in quick succession is
|
|
to read both of these values avoiding a second read delay is desirable.
|
|
|