1 Kernel driver vt1211 2 ==================== 3 4 Supported chips: 5 6 * VIA VT1211 7 8 Prefix: 'vt1211' 9 10 Addresses scanned: none, address read from Super-I/O config space 11 12 Datasheet: Provided by VIA upon request and under NDA 13 14 Authors: Juerg Haefliger <juergh@gmail.com> 15 16 This driver is based on the driver for kernel 2.4 by Mark D. Studebaker and 17 its port to kernel 2.6 by Lars Ekman. 18 19 Thanks to Joseph Chan and Fiona Gatt from VIA for providing documentation and 20 technical support. 21 22 23 Module Parameters 24 ----------------- 25 26 27 * uch_config: int 28 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 to 31 UCH1, bit 1 maps to UCH2 and so on. Setting a bit to 1 32 enables the thermal input of that particular UCH and 33 setting a bit to 0 enables the voltage input. 34 35 * int_mode: int 36 Override the BIOS default temperature interrupt mode. 37 The only possible value is 0 which forces interrupt 38 mode 0. In this mode, any pending interrupt is cleared 39 when the status register is read but is regenerated as 40 long as the temperature stays above the hysteresis 41 limit. 42 43 Be aware that overriding BIOS defaults might cause some unwanted side effects! 44 45 46 Description 47 ----------- 48 49 The VIA VT1211 Super-I/O chip includes complete hardware monitoring 50 capabilities. It monitors 2 dedicated temperature sensor inputs (temp1 and 51 temp2), 1 dedicated voltage (in5) and 2 fans. Additionally, the chip 52 implements 5 universal input channels (UCH1-5) that can be individually 53 programmed to either monitor a voltage or a temperature. 54 55 This chip also provides manual and automatic control of fan speeds (according 56 to the datasheet). The driver only supports automatic control since the manual 57 mode doesn't seem to work as advertised in the datasheet. In fact I couldn't 58 get manual mode to work at all! Be aware that automatic mode hasn't been 59 tested very well (due to the fact that my EPIA M10000 doesn't have the fans 60 connected to the PWM outputs of the VT1211 :-(). 61 62 The following table shows the relationship between the vt1211 inputs and the 63 sysfs nodes. 64 65 =============== ============== =========== ================================ 66 Sensor Voltage Mode Temp Mode Default Use (from the datasheet) 67 =============== ============== =========== ================================ 68 Reading 1 temp1 Intel thermal diode 69 Reading 3 temp2 Internal thermal diode 70 UCH1/Reading2 in0 temp3 NTC type thermistor 71 UCH2 in1 temp4 +2.5V 72 UCH3 in2 temp5 VccP (processor core) 73 UCH4 in3 temp6 +5V 74 UCH5 in4 temp7 +12V 75 +3.3V in5 Internal VCC (+3.3V) 76 =============== ============== =========== ================================ 77 78 79 Voltage Monitoring 80 ------------------ 81 82 Voltages are sampled by an 8-bit ADC with a LSB of ~10mV. The supported input 83 range is thus from 0 to 2.60V. Voltage values outside of this range need 84 external scaling resistors. This external scaling needs to be compensated for 85 via compute lines in sensors.conf, like: 86 87 compute inx @*(1+R1/R2), @/(1+R1/R2) 88 89 The board level scaling resistors according to VIA's recommendation are as 90 follows. And this is of course totally dependent on the actual board 91 implementation :-) You will have to find documentation for your own 92 motherboard and edit sensors.conf accordingly. 93 94 ============= ====== ====== ========= ============ 95 Expected 96 Voltage R1 R2 Divider Raw Value 97 ============= ====== ====== ========= ============ 98 +2.5V 2K 10K 1.2 2083 mV 99 VccP --- --- 1.0 1400 mV [1]_ 100 +5V 14K 10K 2.4 2083 mV 101 +12V 47K 10K 5.7 2105 mV 102 +3.3V (int) 2K 3.4K 1.588 3300 mV [2]_ 103 +3.3V (ext) 6.8K 10K 1.68 1964 mV 104 ============= ====== ====== ========= ============ 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 driver 109 performs the scaling and returns the properly scaled voltage value. 110 111 Each measured voltage has an associated low and high limit which triggers an 112 alarm when crossed. 113 114 115 Temperature Monitoring 116 ---------------------- 117 118 Temperatures are reported in millidegree Celsius. Each measured temperature 119 has a high limit which triggers an alarm if crossed. There is an associated 120 hysteresis value with each temperature below which the temperature has to drop 121 before the alarm is cleared (this is only true for interrupt mode 0). The 122 interrupt mode can be forced to 0 in case the BIOS doesn't do it 123 automatically. See the 'Module Parameters' section for details. 124 125 All temperature channels except temp2 are external. Temp2 is the VT1211 126 internal thermal diode and the driver does all the scaling for temp2 and 127 returns the temperature in millidegree Celsius. For the external channels 128 temp1 and temp3-temp7, scaling depends on the board implementation and needs 129 to be performed in userspace via sensors.conf. 130 131 Temp1 is an Intel-type thermal diode which requires the following formula to 132 convert between sysfs readings and real temperatures: 133 134 compute temp1 (@-Offset)/Gain, (@*Gain)+Offset 135 136 According to the VIA VT1211 BIOS porting guide, the following gain and offset 137 values should be used: 138 139 =============== ======== =========== 140 Diode Type Offset Gain 141 =============== ======== =========== 142 Intel CPU 88.638 0.9528 143 65.000 0.9686 [3]_ 144 VIA C3 Ezra 83.869 0.9528 145 VIA C3 Ezra-T 73.869 0.9528 146 =============== ======== =========== 147 148 .. [3] This is the formula from the lm_sensors 2.10.0 sensors.conf file. I don't 149 know where it comes from or how it was derived, it's just listed here for 150 completeness. 151 152 Temp3-temp7 support NTC thermistors. For these channels, the driver returns 153 the voltages as seen at the individual pins of UCH1-UCH5. The voltage at the 154 pin (Vpin) is formed by a voltage divider made of the thermistor (Rth) and a 155 scaling resistor (Rs):: 156 157 Vpin = 2200 * Rth / (Rs + Rth) (2200 is the ADC max limit of 2200 mV) 158 159 The equation for the thermistor is as follows (google it if you want to know 160 more about it):: 161 162 Rth = Ro * exp(B * (1 / T - 1 / To)) (To is 298.15K (25C) and Ro is the 163 nominal resistance at 25C) 164 165 Mingling the above two equations and assuming Rs = Ro and B = 3435 yields the 166 following 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 + @)))) 170 171 172 Fan Speed Control 173 ----------------- 174 175 The VT1211 provides 2 programmable PWM outputs to control the speeds of 2 176 fans. Writing a 2 to any of the two pwm[1-2]_enable sysfs nodes will put the 177 PWM controller in automatic mode. There is only a single controller that 178 controls both PWM outputs but each PWM output can be individually enabled and 179 disabled. 180 181 Each PWM has 4 associated distinct output duty-cycles: full, high, low and 182 off. Full and off are internally hard-wired to 255 (100%) and 0 (0%), 183 respectively. High and low can be programmed via 184 pwm[1-2]_auto_point[2-3]_pwm. Each PWM output can be associated with a 185 different thermal input but - and here's the weird part - only one set of 186 thermal thresholds exist that controls both PWMs output duty-cycles. The 187 thermal thresholds are accessible via pwm[1-2]_auto_point[1-4]_temp. Note 188 that even though there are 2 sets of 4 auto points each, they map to the same 189 registers in the VT1211 and programming one set is sufficient (actually only 190 the first set pwm1_auto_point[1-4]_temp is writable, the second set is 191 read-only). 192 193 ========================== ========================================= 194 PWM Auto Point PWM Output Duty-Cycle 195 ========================== ========================================= 196 pwm[1-2]_auto_point4_pwm full speed duty-cycle (hard-wired to 255) 197 pwm[1-2]_auto_point3_pwm high speed duty-cycle 198 pwm[1-2]_auto_point2_pwm low speed duty-cycle 199 pwm[1-2]_auto_point1_pwm off duty-cycle (hard-wired to 0) 200 ========================== ========================================= 201 202 ========================== ================= 203 Temp Auto Point Thermal Threshold 204 ========================== ================= 205 pwm[1-2]_auto_point4_temp full speed temp 206 pwm[1-2]_auto_point3_temp high speed temp 207 pwm[1-2]_auto_point2_temp low speed temp 208 pwm[1-2]_auto_point1_temp off temp 209 ========================== ================= 210 211 Long story short, the controller implements the following algorithm to set the 212 PWM output duty-cycle based on the input temperature: 213 214 =================== ======================= ======================== 215 Thermal Threshold Output Duty-Cycle Output Duty-Cycle 216 (Rising Temp) (Falling Temp) 217 =================== ======================= ======================== 218 - full speed duty-cycle full speed duty-cycle 219 full speed temp 220 - high speed duty-cycle full speed duty-cycle 221 high speed temp 222 - low speed duty-cycle high speed duty-cycle 223 low speed temp 224 - off duty-cycle low speed duty-cycle 225 off temp 226 =================== ======================= ========================
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