> This patch adds documentation for the new vt1211 Super-IO driver. > +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 actually only true in interrupt mode "0", right? > + > +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 Celcius. For the external channels Celsius > +temp1 and temp4-temp7, scaling depends on the board implementation and needs temp3? > +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 *) > +VIA C3 Ezra 83.869 0.9528 > +VIA C3 Ezra-T 73.869 0.9528 > + > +*) This is the formula from the current (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)) > + > +Mingling the above two equations and assuming Rs = Ro and B = 3435 yields the and assuming To = 25 degrees C In other words, assuming Rth = Rs at 25 degrees C... > +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-cyle (hard-wired to 255) cycle > +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 > + (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 > + off duty-cycle off duty-cycle > diff -uprN -X linux-2.6.18-rc4-mm-vanilla/Documentation/dontdiff -x drivers -x MAINTAINERS -x usr -x dwarf2-defs.h linux-2.6.18-rc4-mm-vanilla/include/linux/utsrelease.h linux-2.6.18-rc4-mm/include/linux/utsrelease.h > --- linux-2.6.18-rc4-mm-vanilla/include/linux/utsrelease.h 1969-12-31 16:00:00.000000000 -0800 > +++ linux-2.6.18-rc4-mm/include/linux/utsrelease.h 2006-08-16 21:04:49.000000000 -0700 > @@ -0,0 +1 @@ > +#define UTS_RELEASE "2.6.18-rc4-mm1" This shouldn't have been in this patch either ;) Thanks, -- Jean Delvare
