vt1211.rst 9.1 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
  16. Override the BIOS default universal channel (UCH)
  17. configuration for channels 1-5.
  18. Legal values are in the range of 0-31. Bit 0 maps to
  19. UCH1, bit 1 maps to UCH2 and so on. Setting a bit to 1
  20. enables the thermal input of that particular UCH and
  21. setting a bit to 0 enables the voltage input.
  22. * int_mode: int
  23. Override the BIOS default temperature interrupt mode.
  24. The only possible value is 0 which forces interrupt
  25. mode 0. In this mode, any pending interrupt is cleared
  26. when the status register is read but is regenerated as
  27. long as the temperature stays above the hysteresis
  28. limit.
  29. Be aware that overriding BIOS defaults might cause some unwanted side effects!
  30. Description
  31. -----------
  32. The VIA VT1211 Super-I/O chip includes complete hardware monitoring
  33. capabilities. It monitors 2 dedicated temperature sensor inputs (temp1 and
  34. temp2), 1 dedicated voltage (in5) and 2 fans. Additionally, the chip
  35. implements 5 universal input channels (UCH1-5) that can be individually
  36. programmed to either monitor a voltage or a temperature.
  37. This chip also provides manual and automatic control of fan speeds (according
  38. to the datasheet). The driver only supports automatic control since the manual
  39. mode doesn't seem to work as advertised in the datasheet. In fact I couldn't
  40. get manual mode to work at all! Be aware that automatic mode hasn't been
  41. tested very well (due to the fact that my EPIA M10000 doesn't have the fans
  42. connected to the PWM outputs of the VT1211 :-().
  43. The following table shows the relationship between the vt1211 inputs and the
  44. sysfs nodes.
  45. =============== ============== =========== ================================
  46. Sensor Voltage Mode Temp Mode Default Use (from the datasheet)
  47. =============== ============== =========== ================================
  48. Reading 1 temp1 Intel thermal diode
  49. Reading 3 temp2 Internal thermal diode
  50. UCH1/Reading2 in0 temp3 NTC type thermistor
  51. UCH2 in1 temp4 +2.5V
  52. UCH3 in2 temp5 VccP (processor core)
  53. UCH4 in3 temp6 +5V
  54. UCH5 in4 temp7 +12V
  55. +3.3V in5 Internal VCC (+3.3V)
  56. =============== ============== =========== ================================
  57. Voltage Monitoring
  58. ------------------
  59. Voltages are sampled by an 8-bit ADC with a LSB of ~10mV. The supported input
  60. range is thus from 0 to 2.60V. Voltage values outside of this range need
  61. external scaling resistors. This external scaling needs to be compensated for
  62. via compute lines in sensors.conf, like:
  63. compute inx @*(1+R1/R2), @/(1+R1/R2)
  64. The board level scaling resistors according to VIA's recommendation are as
  65. follows. And this is of course totally dependent on the actual board
  66. implementation :-) You will have to find documentation for your own
  67. motherboard and edit sensors.conf accordingly.
  68. ============= ====== ====== ========= ============
  69. Expected
  70. Voltage R1 R2 Divider Raw Value
  71. ============= ====== ====== ========= ============
  72. +2.5V 2K 10K 1.2 2083 mV
  73. VccP --- --- 1.0 1400 mV [1]_
  74. +5V 14K 10K 2.4 2083 mV
  75. +12V 47K 10K 5.7 2105 mV
  76. +3.3V (int) 2K 3.4K 1.588 3300 mV [2]_
  77. +3.3V (ext) 6.8K 10K 1.68 1964 mV
  78. ============= ====== ====== ========= ============
  79. .. [1] Depending on the CPU (1.4V is for a VIA C3 Nehemiah).
  80. .. [2] R1 and R2 for 3.3V (int) are internal to the VT1211 chip and the driver
  81. performs the scaling and returns the properly scaled voltage value.
  82. Each measured voltage has an associated low and high limit which triggers an
  83. alarm when crossed.
  84. Temperature Monitoring
  85. ----------------------
  86. Temperatures are reported in millidegree Celsius. Each measured temperature
  87. has a high limit which triggers an alarm if crossed. There is an associated
  88. hysteresis value with each temperature below which the temperature has to drop
  89. before the alarm is cleared (this is only true for interrupt mode 0). The
  90. interrupt mode can be forced to 0 in case the BIOS doesn't do it
  91. automatically. See the 'Module Parameters' section for details.
  92. All temperature channels except temp2 are external. Temp2 is the VT1211
  93. internal thermal diode and the driver does all the scaling for temp2 and
  94. returns the temperature in millidegree Celsius. For the external channels
  95. temp1 and temp3-temp7, scaling depends on the board implementation and needs
  96. to be performed in userspace via sensors.conf.
  97. Temp1 is an Intel-type thermal diode which requires the following formula to
  98. convert between sysfs readings and real temperatures:
  99. compute temp1 (@-Offset)/Gain, (@*Gain)+Offset
  100. According to the VIA VT1211 BIOS porting guide, the following gain and offset
  101. values should be used:
  102. =============== ======== ===========
  103. Diode Type Offset Gain
  104. =============== ======== ===========
  105. Intel CPU 88.638 0.9528
  106. 65.000 0.9686 [3]_
  107. VIA C3 Ezra 83.869 0.9528
  108. VIA C3 Ezra-T 73.869 0.9528
  109. =============== ======== ===========
  110. .. [3] This is the formula from the lm_sensors 2.10.0 sensors.conf file. I don't
  111. know where it comes from or how it was derived, it's just listed here for
  112. completeness.
  113. Temp3-temp7 support NTC thermistors. For these channels, the driver returns
  114. the voltages as seen at the individual pins of UCH1-UCH5. The voltage at the
  115. pin (Vpin) is formed by a voltage divider made of the thermistor (Rth) and a
  116. scaling resistor (Rs)::
  117. Vpin = 2200 * Rth / (Rs + Rth) (2200 is the ADC max limit of 2200 mV)
  118. The equation for the thermistor is as follows (google it if you want to know
  119. more about it)::
  120. Rth = Ro * exp(B * (1 / T - 1 / To)) (To is 298.15K (25C) and Ro is the
  121. nominal resistance at 25C)
  122. Mingling the above two equations and assuming Rs = Ro and B = 3435 yields the
  123. following formula for sensors.conf::
  124. compute tempx 1 / (1 / 298.15 - (` (2200 / @ - 1)) / 3435) - 273.15,
  125. 2200 / (1 + (^ (3435 / 298.15 - 3435 / (273.15 + @))))
  126. Fan Speed Control
  127. -----------------
  128. The VT1211 provides 2 programmable PWM outputs to control the speeds of 2
  129. fans. Writing a 2 to any of the two pwm[1-2]_enable sysfs nodes will put the
  130. PWM controller in automatic mode. There is only a single controller that
  131. controls both PWM outputs but each PWM output can be individually enabled and
  132. disabled.
  133. Each PWM has 4 associated distinct output duty-cycles: full, high, low and
  134. off. Full and off are internally hard-wired to 255 (100%) and 0 (0%),
  135. respectively. High and low can be programmed via
  136. pwm[1-2]_auto_point[2-3]_pwm. Each PWM output can be associated with a
  137. different thermal input but - and here's the weird part - only one set of
  138. thermal thresholds exist that controls both PWMs output duty-cycles. The
  139. thermal thresholds are accessible via pwm[1-2]_auto_point[1-4]_temp. Note
  140. that even though there are 2 sets of 4 auto points each, they map to the same
  141. registers in the VT1211 and programming one set is sufficient (actually only
  142. the first set pwm1_auto_point[1-4]_temp is writable, the second set is
  143. read-only).
  144. ========================== =========================================
  145. PWM Auto Point PWM Output Duty-Cycle
  146. ========================== =========================================
  147. pwm[1-2]_auto_point4_pwm full speed duty-cycle (hard-wired to 255)
  148. pwm[1-2]_auto_point3_pwm high speed duty-cycle
  149. pwm[1-2]_auto_point2_pwm low speed duty-cycle
  150. pwm[1-2]_auto_point1_pwm off duty-cycle (hard-wired to 0)
  151. ========================== =========================================
  152. ========================== =================
  153. Temp Auto Point Thermal Threshold
  154. ========================== =================
  155. pwm[1-2]_auto_point4_temp full speed temp
  156. pwm[1-2]_auto_point3_temp high speed temp
  157. pwm[1-2]_auto_point2_temp low speed temp
  158. pwm[1-2]_auto_point1_temp off temp
  159. ========================== =================
  160. Long story short, the controller implements the following algorithm to set the
  161. PWM output duty-cycle based on the input temperature:
  162. =================== ======================= ========================
  163. Thermal Threshold Output Duty-Cycle Output Duty-Cycle
  164. (Rising Temp) (Falling Temp)
  165. =================== ======================= ========================
  166. - full speed duty-cycle full speed duty-cycle
  167. full speed temp
  168. - high speed duty-cycle full speed duty-cycle
  169. high speed temp
  170. - low speed duty-cycle high speed duty-cycle
  171. low speed temp
  172. - off duty-cycle low speed duty-cycle
  173. off temp
  174. =================== ======================= ========================