vt1211 8.4 KB

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  1. Kernel driver vt1211
  2. ====================
  3. Supported chips:
  4. * VIA VT1211
  5. Prefix: 'vt1211'
  6. Addresses scanned: none, address read from Super-I/O config space
  7. Datasheet: Provided by VIA upon request and under NDA
  8. Authors: Juerg Haefliger <juergh@gmail.com>
  9. This driver is based on the driver for kernel 2.4 by Mark D. Studebaker and
  10. its port to kernel 2.6 by Lars Ekman.
  11. Thanks to Joseph Chan and Fiona Gatt from VIA for providing documentation and
  12. technical support.
  13. Module Parameters
  14. -----------------
  15. * uch_config: int Override the BIOS default universal channel (UCH)
  16. configuration for channels 1-5.
  17. Legal values are in the range of 0-31. Bit 0 maps to
  18. UCH1, bit 1 maps to UCH2 and so on. Setting a bit to 1
  19. enables the thermal input of that particular UCH and
  20. setting a bit to 0 enables the voltage input.
  21. * int_mode: int Override the BIOS default temperature interrupt mode.
  22. The only possible value is 0 which forces interrupt
  23. mode 0. In this mode, any pending interrupt is cleared
  24. when the status register is read but is regenerated as
  25. long as the temperature stays above the hysteresis
  26. limit.
  27. Be aware that overriding BIOS defaults might cause some unwanted side effects!
  28. Description
  29. -----------
  30. The VIA VT1211 Super-I/O chip includes complete hardware monitoring
  31. capabilities. It monitors 2 dedicated temperature sensor inputs (temp1 and
  32. temp2), 1 dedicated voltage (in5) and 2 fans. Additionally, the chip
  33. implements 5 universal input channels (UCH1-5) that can be individually
  34. programmed to either monitor a voltage or a temperature.
  35. This chip also provides manual and automatic control of fan speeds (according
  36. to the datasheet). The driver only supports automatic control since the manual
  37. mode doesn't seem to work as advertised in the datasheet. In fact I couldn't
  38. get manual mode to work at all! Be aware that automatic mode hasn't been
  39. tested very well (due to the fact that my EPIA M10000 doesn't have the fans
  40. connected to the PWM outputs of the VT1211 :-().
  41. The following table shows the relationship between the vt1211 inputs and the
  42. sysfs nodes.
  43. Sensor Voltage Mode Temp Mode Default Use (from the datasheet)
  44. ------ ------------ --------- --------------------------------
  45. Reading 1 temp1 Intel thermal diode
  46. Reading 3 temp2 Internal thermal diode
  47. UCH1/Reading2 in0 temp3 NTC type thermistor
  48. UCH2 in1 temp4 +2.5V
  49. UCH3 in2 temp5 VccP (processor core)
  50. UCH4 in3 temp6 +5V
  51. UCH5 in4 temp7 +12V
  52. +3.3V in5 Internal VCC (+3.3V)
  53. Voltage Monitoring
  54. ------------------
  55. Voltages are sampled by an 8-bit ADC with a LSB of ~10mV. The supported input
  56. range is thus from 0 to 2.60V. Voltage values outside of this range need
  57. external scaling resistors. This external scaling needs to be compensated for
  58. via compute lines in sensors.conf, like:
  59. compute inx @*(1+R1/R2), @/(1+R1/R2)
  60. The board level scaling resistors according to VIA's recommendation are as
  61. follows. And this is of course totally dependent on the actual board
  62. implementation :-) You will have to find documentation for your own
  63. motherboard and edit sensors.conf accordingly.
  64. Expected
  65. Voltage R1 R2 Divider Raw Value
  66. -----------------------------------------------
  67. +2.5V 2K 10K 1.2 2083 mV
  68. VccP --- --- 1.0 1400 mV (1)
  69. +5V 14K 10K 2.4 2083 mV
  70. +12V 47K 10K 5.7 2105 mV
  71. +3.3V (int) 2K 3.4K 1.588 3300 mV (2)
  72. +3.3V (ext) 6.8K 10K 1.68 1964 mV
  73. (1) Depending on the CPU (1.4V is for a VIA C3 Nehemiah).
  74. (2) R1 and R2 for 3.3V (int) are internal to the VT1211 chip and the driver
  75. performs the scaling and returns the properly scaled voltage value.
  76. Each measured voltage has an associated low and high limit which triggers an
  77. alarm when crossed.
  78. Temperature Monitoring
  79. ----------------------
  80. Temperatures are reported in millidegree Celsius. Each measured temperature
  81. has a high limit which triggers an alarm if crossed. There is an associated
  82. hysteresis value with each temperature below which the temperature has to drop
  83. before the alarm is cleared (this is only true for interrupt mode 0). The
  84. interrupt mode can be forced to 0 in case the BIOS doesn't do it
  85. automatically. See the 'Module Parameters' section for details.
  86. All temperature channels except temp2 are external. Temp2 is the VT1211
  87. internal thermal diode and the driver does all the scaling for temp2 and
  88. returns the temperature in millidegree Celsius. For the external channels
  89. temp1 and temp3-temp7, scaling depends on the board implementation and needs
  90. to be performed in userspace via sensors.conf.
  91. Temp1 is an Intel-type thermal diode which requires the following formula to
  92. convert between sysfs readings and real temperatures:
  93. compute temp1 (@-Offset)/Gain, (@*Gain)+Offset
  94. According to the VIA VT1211 BIOS porting guide, the following gain and offset
  95. values should be used:
  96. Diode Type Offset Gain
  97. ---------- ------ ----
  98. Intel CPU 88.638 0.9528
  99. 65.000 0.9686 *)
  100. VIA C3 Ezra 83.869 0.9528
  101. VIA C3 Ezra-T 73.869 0.9528
  102. *) This is the formula from the lm_sensors 2.10.0 sensors.conf file. I don't
  103. know where it comes from or how it was derived, it's just listed here for
  104. completeness.
  105. Temp3-temp7 support NTC thermistors. For these channels, the driver returns
  106. the voltages as seen at the individual pins of UCH1-UCH5. The voltage at the
  107. pin (Vpin) is formed by a voltage divider made of the thermistor (Rth) and a
  108. scaling resistor (Rs):
  109. Vpin = 2200 * Rth / (Rs + Rth) (2200 is the ADC max limit of 2200 mV)
  110. The equation for the thermistor is as follows (google it if you want to know
  111. more about it):
  112. Rth = Ro * exp(B * (1 / T - 1 / To)) (To is 298.15K (25C) and Ro is the
  113. nominal resistance at 25C)
  114. Mingling the above two equations and assuming Rs = Ro and B = 3435 yields the
  115. following formula for sensors.conf:
  116. compute tempx 1 / (1 / 298.15 - (` (2200 / @ - 1)) / 3435) - 273.15,
  117. 2200 / (1 + (^ (3435 / 298.15 - 3435 / (273.15 + @))))
  118. Fan Speed Control
  119. -----------------
  120. The VT1211 provides 2 programmable PWM outputs to control the speeds of 2
  121. fans. Writing a 2 to any of the two pwm[1-2]_enable sysfs nodes will put the
  122. PWM controller in automatic mode. There is only a single controller that
  123. controls both PWM outputs but each PWM output can be individually enabled and
  124. disabled.
  125. Each PWM has 4 associated distinct output duty-cycles: full, high, low and
  126. off. Full and off are internally hard-wired to 255 (100%) and 0 (0%),
  127. respectively. High and low can be programmed via
  128. pwm[1-2]_auto_point[2-3]_pwm. Each PWM output can be associated with a
  129. different thermal input but - and here's the weird part - only one set of
  130. thermal thresholds exist that controls both PWMs output duty-cycles. The
  131. thermal thresholds are accessible via pwm[1-2]_auto_point[1-4]_temp. Note
  132. that even though there are 2 sets of 4 auto points each, they map to the same
  133. registers in the VT1211 and programming one set is sufficient (actually only
  134. the first set pwm1_auto_point[1-4]_temp is writable, the second set is
  135. read-only).
  136. PWM Auto Point PWM Output Duty-Cycle
  137. ------------------------------------------------
  138. pwm[1-2]_auto_point4_pwm full speed duty-cycle (hard-wired to 255)
  139. pwm[1-2]_auto_point3_pwm high speed duty-cycle
  140. pwm[1-2]_auto_point2_pwm low speed duty-cycle
  141. pwm[1-2]_auto_point1_pwm off duty-cycle (hard-wired to 0)
  142. Temp Auto Point Thermal Threshold
  143. ---------------------------------------------
  144. pwm[1-2]_auto_point4_temp full speed temp
  145. pwm[1-2]_auto_point3_temp high speed temp
  146. pwm[1-2]_auto_point2_temp low speed temp
  147. pwm[1-2]_auto_point1_temp off temp
  148. Long story short, the controller implements the following algorithm to set the
  149. PWM output duty-cycle based on the input temperature:
  150. Thermal Threshold Output Duty-Cycle
  151. (Rising Temp) (Falling Temp)
  152. ----------------------------------------------------------
  153. full speed duty-cycle full speed duty-cycle
  154. full speed temp
  155. high speed duty-cycle full speed duty-cycle
  156. high speed temp
  157. low speed duty-cycle high speed duty-cycle
  158. low speed temp
  159. off duty-cycle low speed duty-cycle
  160. off temp