mirror of
https://github.com/torvalds/linux.git
synced 2024-11-22 04:02:20 +00:00
7ebd8b66dd
Now that all files were converted to ReST format, rename them and add an index. Signed-off-by: Mauro Carvalho Chehab <mchehab+samsung@kernel.org> Signed-off-by: Guenter Roeck <linux@roeck-us.net>
227 lines
9.1 KiB
ReStructuredText
227 lines
9.1 KiB
ReStructuredText
Kernel driver vt1211
|
|
====================
|
|
|
|
Supported chips:
|
|
|
|
* VIA VT1211
|
|
|
|
Prefix: 'vt1211'
|
|
|
|
Addresses scanned: none, address read from Super-I/O config space
|
|
|
|
Datasheet: Provided by VIA upon request and under NDA
|
|
|
|
Authors: Juerg Haefliger <juergh@gmail.com>
|
|
|
|
This driver is based on the driver for kernel 2.4 by Mark D. Studebaker and
|
|
its port to kernel 2.6 by Lars Ekman.
|
|
|
|
Thanks to Joseph Chan and Fiona Gatt from VIA for providing documentation and
|
|
technical support.
|
|
|
|
|
|
Module Parameters
|
|
-----------------
|
|
|
|
|
|
* uch_config: int
|
|
Override the BIOS default universal channel (UCH)
|
|
configuration for channels 1-5.
|
|
Legal values are in the range of 0-31. Bit 0 maps to
|
|
UCH1, bit 1 maps to UCH2 and so on. Setting a bit to 1
|
|
enables the thermal input of that particular UCH and
|
|
setting a bit to 0 enables the voltage input.
|
|
|
|
* int_mode: int
|
|
Override the BIOS default temperature interrupt mode.
|
|
The only possible value is 0 which forces interrupt
|
|
mode 0. In this mode, any pending interrupt is cleared
|
|
when the status register is read but is regenerated as
|
|
long as the temperature stays above the hysteresis
|
|
limit.
|
|
|
|
Be aware that overriding BIOS defaults might cause some unwanted side effects!
|
|
|
|
|
|
Description
|
|
-----------
|
|
|
|
The VIA VT1211 Super-I/O chip includes complete hardware monitoring
|
|
capabilities. It monitors 2 dedicated temperature sensor inputs (temp1 and
|
|
temp2), 1 dedicated voltage (in5) and 2 fans. Additionally, the chip
|
|
implements 5 universal input channels (UCH1-5) that can be individually
|
|
programmed to either monitor a voltage or a temperature.
|
|
|
|
This chip also provides manual and automatic control of fan speeds (according
|
|
to the datasheet). The driver only supports automatic control since the manual
|
|
mode doesn't seem to work as advertised in the datasheet. In fact I couldn't
|
|
get manual mode to work at all! Be aware that automatic mode hasn't been
|
|
tested very well (due to the fact that my EPIA M10000 doesn't have the fans
|
|
connected to the PWM outputs of the VT1211 :-().
|
|
|
|
The following table shows the relationship between the vt1211 inputs and the
|
|
sysfs nodes.
|
|
|
|
=============== ============== =========== ================================
|
|
Sensor Voltage Mode Temp Mode Default Use (from the datasheet)
|
|
=============== ============== =========== ================================
|
|
Reading 1 temp1 Intel thermal diode
|
|
Reading 3 temp2 Internal thermal diode
|
|
UCH1/Reading2 in0 temp3 NTC type thermistor
|
|
UCH2 in1 temp4 +2.5V
|
|
UCH3 in2 temp5 VccP (processor core)
|
|
UCH4 in3 temp6 +5V
|
|
UCH5 in4 temp7 +12V
|
|
+3.3V in5 Internal VCC (+3.3V)
|
|
=============== ============== =========== ================================
|
|
|
|
|
|
Voltage Monitoring
|
|
------------------
|
|
|
|
Voltages are sampled by an 8-bit ADC with a LSB of ~10mV. The supported input
|
|
range is thus from 0 to 2.60V. Voltage values outside of this range need
|
|
external scaling resistors. This external scaling needs to be compensated for
|
|
via compute lines in sensors.conf, like:
|
|
|
|
compute inx @*(1+R1/R2), @/(1+R1/R2)
|
|
|
|
The board level scaling resistors according to VIA's recommendation are as
|
|
follows. And this is of course totally dependent on the actual board
|
|
implementation :-) You will have to find documentation for your own
|
|
motherboard and edit sensors.conf accordingly.
|
|
|
|
============= ====== ====== ========= ============
|
|
Expected
|
|
Voltage R1 R2 Divider Raw Value
|
|
============= ====== ====== ========= ============
|
|
+2.5V 2K 10K 1.2 2083 mV
|
|
VccP --- --- 1.0 1400 mV [1]_
|
|
+5V 14K 10K 2.4 2083 mV
|
|
+12V 47K 10K 5.7 2105 mV
|
|
+3.3V (int) 2K 3.4K 1.588 3300 mV [2]_
|
|
+3.3V (ext) 6.8K 10K 1.68 1964 mV
|
|
============= ====== ====== ========= ============
|
|
|
|
.. [1] Depending on the CPU (1.4V is for a VIA C3 Nehemiah).
|
|
|
|
.. [2] R1 and R2 for 3.3V (int) are internal to the VT1211 chip and the driver
|
|
performs the scaling and returns the properly scaled voltage value.
|
|
|
|
Each measured voltage has an associated low and high limit which triggers an
|
|
alarm when crossed.
|
|
|
|
|
|
Temperature Monitoring
|
|
----------------------
|
|
|
|
Temperatures are reported in millidegree Celsius. Each measured temperature
|
|
has a high limit which triggers an alarm if crossed. There is an associated
|
|
hysteresis value with each temperature below which the temperature has to drop
|
|
before the alarm is cleared (this is only true for interrupt mode 0). The
|
|
interrupt mode can be forced to 0 in case the BIOS doesn't do it
|
|
automatically. See the 'Module Parameters' section for details.
|
|
|
|
All temperature channels except temp2 are external. Temp2 is the VT1211
|
|
internal thermal diode and the driver does all the scaling for temp2 and
|
|
returns the temperature in millidegree Celsius. For the external channels
|
|
temp1 and temp3-temp7, scaling depends on the board implementation and needs
|
|
to be performed in userspace via sensors.conf.
|
|
|
|
Temp1 is an Intel-type thermal diode which requires the following formula to
|
|
convert between sysfs readings and real temperatures:
|
|
|
|
compute temp1 (@-Offset)/Gain, (@*Gain)+Offset
|
|
|
|
According to the VIA VT1211 BIOS porting guide, the following gain and offset
|
|
values should be used:
|
|
|
|
=============== ======== ===========
|
|
Diode Type Offset Gain
|
|
=============== ======== ===========
|
|
Intel CPU 88.638 0.9528
|
|
65.000 0.9686 [3]_
|
|
VIA C3 Ezra 83.869 0.9528
|
|
VIA C3 Ezra-T 73.869 0.9528
|
|
=============== ======== ===========
|
|
|
|
.. [3] This is the formula from the lm_sensors 2.10.0 sensors.conf file. I don't
|
|
know where it comes from or how it was derived, it's just listed here for
|
|
completeness.
|
|
|
|
Temp3-temp7 support NTC thermistors. For these channels, the driver returns
|
|
the voltages as seen at the individual pins of UCH1-UCH5. The voltage at the
|
|
pin (Vpin) is formed by a voltage divider made of the thermistor (Rth) and a
|
|
scaling resistor (Rs)::
|
|
|
|
Vpin = 2200 * Rth / (Rs + Rth) (2200 is the ADC max limit of 2200 mV)
|
|
|
|
The equation for the thermistor is as follows (google it if you want to know
|
|
more about it)::
|
|
|
|
Rth = Ro * exp(B * (1 / T - 1 / To)) (To is 298.15K (25C) and Ro is the
|
|
nominal resistance at 25C)
|
|
|
|
Mingling the above two equations and assuming Rs = Ro and B = 3435 yields the
|
|
following formula for sensors.conf::
|
|
|
|
compute tempx 1 / (1 / 298.15 - (` (2200 / @ - 1)) / 3435) - 273.15,
|
|
2200 / (1 + (^ (3435 / 298.15 - 3435 / (273.15 + @))))
|
|
|
|
|
|
Fan Speed Control
|
|
-----------------
|
|
|
|
The VT1211 provides 2 programmable PWM outputs to control the speeds of 2
|
|
fans. Writing a 2 to any of the two pwm[1-2]_enable sysfs nodes will put the
|
|
PWM controller in automatic mode. There is only a single controller that
|
|
controls both PWM outputs but each PWM output can be individually enabled and
|
|
disabled.
|
|
|
|
Each PWM has 4 associated distinct output duty-cycles: full, high, low and
|
|
off. Full and off are internally hard-wired to 255 (100%) and 0 (0%),
|
|
respectively. High and low can be programmed via
|
|
pwm[1-2]_auto_point[2-3]_pwm. Each PWM output can be associated with a
|
|
different thermal input but - and here's the weird part - only one set of
|
|
thermal thresholds exist that controls both PWMs output duty-cycles. The
|
|
thermal thresholds are accessible via pwm[1-2]_auto_point[1-4]_temp. Note
|
|
that even though there are 2 sets of 4 auto points each, they map to the same
|
|
registers in the VT1211 and programming one set is sufficient (actually only
|
|
the first set pwm1_auto_point[1-4]_temp is writable, the second set is
|
|
read-only).
|
|
|
|
========================== =========================================
|
|
PWM Auto Point PWM Output Duty-Cycle
|
|
========================== =========================================
|
|
pwm[1-2]_auto_point4_pwm full speed duty-cycle (hard-wired to 255)
|
|
pwm[1-2]_auto_point3_pwm high speed duty-cycle
|
|
pwm[1-2]_auto_point2_pwm low speed duty-cycle
|
|
pwm[1-2]_auto_point1_pwm off duty-cycle (hard-wired to 0)
|
|
========================== =========================================
|
|
|
|
========================== =================
|
|
Temp Auto Point Thermal Threshold
|
|
========================== =================
|
|
pwm[1-2]_auto_point4_temp full speed temp
|
|
pwm[1-2]_auto_point3_temp high speed temp
|
|
pwm[1-2]_auto_point2_temp low speed temp
|
|
pwm[1-2]_auto_point1_temp off temp
|
|
========================== =================
|
|
|
|
Long story short, the controller implements the following algorithm to set the
|
|
PWM output duty-cycle based on the input temperature:
|
|
|
|
=================== ======================= ========================
|
|
Thermal Threshold Output Duty-Cycle Output Duty-Cycle
|
|
(Rising Temp) (Falling Temp)
|
|
=================== ======================= ========================
|
|
- full speed duty-cycle full speed duty-cycle
|
|
full speed temp
|
|
- high speed duty-cycle full speed duty-cycle
|
|
high speed temp
|
|
- low speed duty-cycle high speed duty-cycle
|
|
low speed temp
|
|
- off duty-cycle low speed duty-cycle
|
|
off temp
|
|
=================== ======================= ========================
|