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1Kernel driver vt12112====================3 4Supported chips:5 6 * VIA VT12117 8 Prefix: 'vt1211'9 10 Addresses scanned: none, address read from Super-I/O config space11 12 Datasheet: Provided by VIA upon request and under NDA13 14Authors: Juerg Haefliger <juergh@gmail.com>15 16This driver is based on the driver for kernel 2.4 by Mark D. Studebaker and17its port to kernel 2.6 by Lars Ekman.18 19Thanks to Joseph Chan and Fiona Gatt from VIA for providing documentation and20technical support.21 22 23Module Parameters24-----------------25 26 27* uch_config: int28 Override the BIOS default universal channel (UCH)29 configuration for channels 1-5.30 Legal values are in the range of 0-31. Bit 0 maps to31 UCH1, bit 1 maps to UCH2 and so on. Setting a bit to 132 enables the thermal input of that particular UCH and33 setting a bit to 0 enables the voltage input.34 35* int_mode: int36 Override the BIOS default temperature interrupt mode.37 The only possible value is 0 which forces interrupt38 mode 0. In this mode, any pending interrupt is cleared39 when the status register is read but is regenerated as40 long as the temperature stays above the hysteresis41 limit.42 43Be aware that overriding BIOS defaults might cause some unwanted side effects!44 45 46Description47-----------48 49The VIA VT1211 Super-I/O chip includes complete hardware monitoring50capabilities. It monitors 2 dedicated temperature sensor inputs (temp1 and51temp2), 1 dedicated voltage (in5) and 2 fans. Additionally, the chip52implements 5 universal input channels (UCH1-5) that can be individually53programmed to either monitor a voltage or a temperature.54 55This chip also provides manual and automatic control of fan speeds (according56to the datasheet). The driver only supports automatic control since the manual57mode doesn't seem to work as advertised in the datasheet. In fact I couldn't58get manual mode to work at all! Be aware that automatic mode hasn't been59tested very well (due to the fact that my EPIA M10000 doesn't have the fans60connected to the PWM outputs of the VT1211 :-().61 62The following table shows the relationship between the vt1211 inputs and the63sysfs nodes.64 65=============== ============== =========== ================================66Sensor Voltage Mode Temp Mode Default Use (from the datasheet)67=============== ============== =========== ================================68Reading 1 temp1 Intel thermal diode69Reading 3 temp2 Internal thermal diode70UCH1/Reading2 in0 temp3 NTC type thermistor71UCH2 in1 temp4 +2.5V72UCH3 in2 temp5 VccP (processor core)73UCH4 in3 temp6 +5V74UCH5 in4 temp7 +12V75+3.3V in5 Internal VCC (+3.3V)76=============== ============== =========== ================================77 78 79Voltage Monitoring80------------------81 82Voltages are sampled by an 8-bit ADC with a LSB of ~10mV. The supported input83range is thus from 0 to 2.60V. Voltage values outside of this range need84external scaling resistors. This external scaling needs to be compensated for85via compute lines in sensors.conf, like:86 87compute inx @*(1+R1/R2), @/(1+R1/R2)88 89The board level scaling resistors according to VIA's recommendation are as90follows. And this is of course totally dependent on the actual board91implementation :-) You will have to find documentation for your own92motherboard and edit sensors.conf accordingly.93 94============= ====== ====== ========= ============95 Expected96Voltage R1 R2 Divider Raw Value97============= ====== ====== ========= ============98+2.5V 2K 10K 1.2 2083 mV99VccP --- --- 1.0 1400 mV [1]_100+5V 14K 10K 2.4 2083 mV101+12V 47K 10K 5.7 2105 mV102+3.3V (int) 2K 3.4K 1.588 3300 mV [2]_103+3.3V (ext) 6.8K 10K 1.68 1964 mV104============= ====== ====== ========= ============105 106.. [1] Depending on the CPU (1.4V is for a VIA C3 Nehemiah).107 108.. [2] R1 and R2 for 3.3V (int) are internal to the VT1211 chip and the driver109 performs the scaling and returns the properly scaled voltage value.110 111Each measured voltage has an associated low and high limit which triggers an112alarm when crossed.113 114 115Temperature Monitoring116----------------------117 118Temperatures are reported in millidegree Celsius. Each measured temperature119has a high limit which triggers an alarm if crossed. There is an associated120hysteresis value with each temperature below which the temperature has to drop121before the alarm is cleared (this is only true for interrupt mode 0). The122interrupt mode can be forced to 0 in case the BIOS doesn't do it123automatically. See the 'Module Parameters' section for details.124 125All temperature channels except temp2 are external. Temp2 is the VT1211126internal thermal diode and the driver does all the scaling for temp2 and127returns the temperature in millidegree Celsius. For the external channels128temp1 and temp3-temp7, scaling depends on the board implementation and needs129to be performed in userspace via sensors.conf.130 131Temp1 is an Intel-type thermal diode which requires the following formula to132convert between sysfs readings and real temperatures:133 134compute temp1 (@-Offset)/Gain, (@*Gain)+Offset135 136According to the VIA VT1211 BIOS porting guide, the following gain and offset137values should be used:138 139=============== ======== ===========140Diode Type Offset Gain141=============== ======== ===========142Intel CPU 88.638 0.9528143 65.000 0.9686 [3]_144VIA C3 Ezra 83.869 0.9528145VIA C3 Ezra-T 73.869 0.9528146=============== ======== ===========147 148.. [3] This is the formula from the lm_sensors 2.10.0 sensors.conf file. I don't149 know where it comes from or how it was derived, it's just listed here for150 completeness.151 152Temp3-temp7 support NTC thermistors. For these channels, the driver returns153the voltages as seen at the individual pins of UCH1-UCH5. The voltage at the154pin (Vpin) is formed by a voltage divider made of the thermistor (Rth) and a155scaling resistor (Rs)::156 157 Vpin = 2200 * Rth / (Rs + Rth) (2200 is the ADC max limit of 2200 mV)158 159The equation for the thermistor is as follows (google it if you want to know160more about it)::161 162 Rth = Ro * exp(B * (1 / T - 1 / To)) (To is 298.15K (25C) and Ro is the163 nominal resistance at 25C)164 165Mingling the above two equations and assuming Rs = Ro and B = 3435 yields the166following formula for sensors.conf::167 168 compute tempx 1 / (1 / 298.15 - (` (2200 / @ - 1)) / 3435) - 273.15,169 2200 / (1 + (^ (3435 / 298.15 - 3435 / (273.15 + @))))170 171 172Fan Speed Control173-----------------174 175The VT1211 provides 2 programmable PWM outputs to control the speeds of 2176fans. Writing a 2 to any of the two pwm[1-2]_enable sysfs nodes will put the177PWM controller in automatic mode. There is only a single controller that178controls both PWM outputs but each PWM output can be individually enabled and179disabled.180 181Each PWM has 4 associated distinct output duty-cycles: full, high, low and182off. Full and off are internally hard-wired to 255 (100%) and 0 (0%),183respectively. High and low can be programmed via184pwm[1-2]_auto_point[2-3]_pwm. Each PWM output can be associated with a185different thermal input but - and here's the weird part - only one set of186thermal thresholds exist that controls both PWMs output duty-cycles. The187thermal thresholds are accessible via pwm[1-2]_auto_point[1-4]_temp. Note188that even though there are 2 sets of 4 auto points each, they map to the same189registers in the VT1211 and programming one set is sufficient (actually only190the first set pwm1_auto_point[1-4]_temp is writable, the second set is191read-only).192 193========================== =========================================194PWM Auto Point PWM Output Duty-Cycle195========================== =========================================196pwm[1-2]_auto_point4_pwm full speed duty-cycle (hard-wired to 255)197pwm[1-2]_auto_point3_pwm high speed duty-cycle198pwm[1-2]_auto_point2_pwm low speed duty-cycle199pwm[1-2]_auto_point1_pwm off duty-cycle (hard-wired to 0)200========================== =========================================201 202========================== =================203Temp Auto Point Thermal Threshold204========================== =================205pwm[1-2]_auto_point4_temp full speed temp206pwm[1-2]_auto_point3_temp high speed temp207pwm[1-2]_auto_point2_temp low speed temp208pwm[1-2]_auto_point1_temp off temp209========================== =================210 211Long story short, the controller implements the following algorithm to set the212PWM output duty-cycle based on the input temperature:213 214=================== ======================= ========================215Thermal Threshold Output Duty-Cycle Output Duty-Cycle216 (Rising Temp) (Falling Temp)217=================== ======================= ========================218- full speed duty-cycle full speed duty-cycle219full speed temp220- high speed duty-cycle full speed duty-cycle221high speed temp222- low speed duty-cycle high speed duty-cycle223low speed temp224- off duty-cycle low speed duty-cycle225off temp226=================== ======================= ========================227