Documentation/hwmon/jc42

   1 Kernel driver jc42
   2 ==================
   3
   4 Supported chips:
   5   * Analog Devices ADT7408
   6     Datasheets:
   7         http://www.analog.com/static/imported-files/data_sheets/ADT7408.pdf
   8   * Atmel AT30TS00
   9     Datasheets:
  10         http://www.atmel.com/Images/doc8585.pdf
  11   * IDT TSE2002B3, TSE2002GB2, TS3000B3, TS3000GB2
  12     Datasheets:
  13         http://www.idt.com/sites/default/files/documents/IDT_TSE2002B3C_DST_20100512_120303152056.pdf
  14         http://www.idt.com/sites/default/files/documents/IDT_TSE2002GB2A1_DST_20111107_120303145914.pdf
  15         http://www.idt.com/sites/default/files/documents/IDT_TS3000B3A_DST_20101129_120303152013.pdf
  16         http://www.idt.com/sites/default/files/documents/IDT_TS3000GB2A1_DST_20111104_120303151012.pdf
  17   * Maxim MAX6604
  18     Datasheets:
  19         http://datasheets.maxim-ic.com/en/ds/MAX6604.pdf
  20   * Microchip MCP9804, MCP9805, MCP98242, MCP98243, MCP9843
  21     Datasheets:
  22         http://ww1.microchip.com/downloads/en/DeviceDoc/22203C.pdf
  23         http://ww1.microchip.com/downloads/en/DeviceDoc/21977b.pdf
  24         http://ww1.microchip.com/downloads/en/DeviceDoc/21996a.pdf
  25         http://ww1.microchip.com/downloads/en/DeviceDoc/22153c.pdf
  26   * NXP Semiconductors SE97, SE97B, SE98, SE98A
  27     Datasheets:
  28         http://www.nxp.com/documents/data_sheet/SE97.pdf
  29         http://www.nxp.com/documents/data_sheet/SE97B.pdf
  30         http://www.nxp.com/documents/data_sheet/SE98.pdf
  31         http://www.nxp.com/documents/data_sheet/SE98A.pdf
  32   * ON Semiconductor CAT34TS02, CAT6095
  33     Datasheet:
  34         http://www.onsemi.com/pub_link/Collateral/CAT34TS02-D.PDF
  35         http://www.onsemi.com/pub/Collateral/CAT6095-D.PDF
  36   * ST Microelectronics STTS424, STTS424E02, STTS2002, STTS3000
  37     Datasheets:
  38         http://www.st.com/internet/com/TECHNICAL_RESOURCES/TECHNICAL_LITERATURE/DATASHEET/CD00157556.pdf
  39         http://www.st.com/internet/com/TECHNICAL_RESOURCES/TECHNICAL_LITERATURE/DATASHEET/CD00157558.pdf
  40         http://www.st.com/internet/com/TECHNICAL_RESOURCES/TECHNICAL_LITERATURE/DATASHEET/CD00225278.pdf
  41         http://www.st.com/internet/com/TECHNICAL_RESOURCES/TECHNICAL_LITERATURE/DATA_BRIEF/CD00270920.pdf
  42   * JEDEC JC 42.4 compliant temperature sensor chips
  43     Datasheet:
  44         http://www.jedec.org/sites/default/files/docs/4_01_04R19.pdf
  45
  46   Common for all chips:
  47     Prefix: 'jc42'
  48     Addresses scanned: I2C 0x18 - 0x1f
  49
  50 Author:
  51         Guenter Roeck <guenter.roeck@ericsson.com>
  52
  53
  54 Description
  55 -----------
  56
  57 This driver implements support for JEDEC JC 42.4 compliant temperature sensors,
  58 which are used on many DDR3 memory modules for mobile devices and servers. Some
  59 systems use the sensor to prevent memory overheating by automatically throttling
  60 the memory controller.
  61
  62 The driver auto-detects the chips listed above, but can be manually instantiated
  63 to support other JC 42.4 compliant chips.
  64
  65 Example: the following will load the driver for a generic JC 42.4 compliant
  66 temperature sensor at address 0x18 on I2C bus #1:
  67
  68 # modprobe jc42
  69 # echo jc42 0x18 > /sys/bus/i2c/devices/i2c-1/new_device
  70
  71 A JC 42.4 compliant chip supports a single temperature sensor. Minimum, maximum,
  72 and critical temperature can be configured. There are alarms for high, low,
  73 and critical thresholds.
  74
  75 There is also an hysteresis to control the thresholds for resetting alarms.
  76 Per JC 42.4 specification, the hysteresis threshold can be configured to 0, 1.5,
  77 3.0, and 6.0 degrees C. Configured hysteresis values will be rounded to those
  78 limits. The chip supports only a single register to configure the hysteresis,
  79 which applies to all limits. This register can be written by writing into
  80 temp1_crit_hyst. Other hysteresis attributes are read-only.
  81
  82 If the BIOS has configured the sensor for automatic temperature management, it
  83 is likely that it has locked the registers, i.e., that the temperature limits
  84 cannot be changed.
  85
  86 Sysfs entries
  87 -------------
  88
  89 temp1_input             Temperature (RO)
  90 temp1_min               Minimum temperature (RO or RW)
  91 temp1_max               Maximum temperature (RO or RW)
  92 temp1_crit              Critical high temperature (RO or RW)
  93
  94 temp1_crit_hyst         Critical hysteresis temperature (RO or RW)
  95 temp1_max_hyst          Maximum hysteresis temperature (RO)
  96
  97 temp1_min_alarm         Temperature low alarm
  98 temp1_max_alarm         Temperature high alarm
  99 temp1_crit_alarm        Temperature critical alarm