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, AT30TS002A/B, AT30TSE004A
   9     Datasheets:
  10         http://www.atmel.com/Images/doc8585.pdf
  11         http://www.atmel.com/Images/doc8711.pdf
  12         http://www.atmel.com/Images/Atmel-8852-SEEPROM-AT30TSE002A-Datasheet.pdf
  13         http://www.atmel.com/Images/Atmel-8868-DTS-AT30TSE004A-Datasheet.pdf
  14   * IDT TSE2002B3, TSE2002GB2, TSE2004GB2, TS3000B3, TS3000GB0, TS3000GB2,
  15         TS3001GB2
  16     Datasheets:
  17         Available from IDT web site
  18   * Maxim MAX6604
  19     Datasheets:
  20         http://datasheets.maxim-ic.com/en/ds/MAX6604.pdf
  21   * Microchip MCP9804, MCP9805, MCP98242, MCP98243, MCP98244, MCP9843
  22     Datasheets:
  23         http://ww1.microchip.com/downloads/en/DeviceDoc/22203C.pdf
  24         http://ww1.microchip.com/downloads/en/DeviceDoc/21977b.pdf
  25         http://ww1.microchip.com/downloads/en/DeviceDoc/21996a.pdf
  26         http://ww1.microchip.com/downloads/en/DeviceDoc/22153c.pdf
  27         http://ww1.microchip.com/downloads/en/DeviceDoc/22327A.pdf
  28   * NXP Semiconductors SE97, SE97B, SE98, SE98A
  29     Datasheets:
  30         http://www.nxp.com/documents/data_sheet/SE97.pdf
  31         http://www.nxp.com/documents/data_sheet/SE97B.pdf
  32         http://www.nxp.com/documents/data_sheet/SE98.pdf
  33         http://www.nxp.com/documents/data_sheet/SE98A.pdf
  34   * ON Semiconductor CAT34TS02, CAT6095
  35     Datasheet:
  36         http://www.onsemi.com/pub_link/Collateral/CAT34TS02-D.PDF
  37         http://www.onsemi.com/pub/Collateral/CAT6095-D.PDF
  38   * ST Microelectronics STTS424, STTS424E02, STTS2002, STTS2004, STTS3000
  39     Datasheets:
  40         http://www.st.com/web/en/resource/technical/document/datasheet/CD00157556.pdf
  41         http://www.st.com/web/en/resource/technical/document/datasheet/CD00157558.pdf
  42         http://www.st.com/web/en/resource/technical/document/datasheet/CD00266638.pdf
  43         http://www.st.com/web/en/resource/technical/document/datasheet/CD00225278.pdf
  44         http://www.st.com/web/en/resource/technical/document/datasheet/DM00076709.pdf
  45   * JEDEC JC 42.4 compliant temperature sensor chips
  46     Datasheet:
  47         http://www.jedec.org/sites/default/files/docs/4_01_04R19.pdf
  48
  49   Common for all chips:
  50     Prefix: 'jc42'
  51     Addresses scanned: I2C 0x18 - 0x1f
  52
  53 Author:
  54         Guenter Roeck <linux@roeck-us.net>
  55
  56
  57 Description
  58 -----------
  59
  60 This driver implements support for JEDEC JC 42.4 compliant temperature sensors,
  61 which are used on many DDR3 memory modules for mobile devices and servers. Some
  62 systems use the sensor to prevent memory overheating by automatically throttling
  63 the memory controller.
  64
  65 The driver auto-detects the chips listed above, but can be manually instantiated
  66 to support other JC 42.4 compliant chips.
  67
  68 Example: the following will load the driver for a generic JC 42.4 compliant
  69 temperature sensor at address 0x18 on I2C bus #1:
  70
  71 # modprobe jc42
  72 # echo jc42 0x18 > /sys/bus/i2c/devices/i2c-1/new_device
  73
  74 A JC 42.4 compliant chip supports a single temperature sensor. Minimum, maximum,
  75 and critical temperature can be configured. There are alarms for high, low,
  76 and critical thresholds.
  77
  78 There is also an hysteresis to control the thresholds for resetting alarms.
  79 Per JC 42.4 specification, the hysteresis threshold can be configured to 0, 1.5,
  80 3.0, and 6.0 degrees C. Configured hysteresis values will be rounded to those
  81 limits. The chip supports only a single register to configure the hysteresis,
  82 which applies to all limits. This register can be written by writing into
  83 temp1_crit_hyst. Other hysteresis attributes are read-only.
  84
  85 If the BIOS has configured the sensor for automatic temperature management, it
  86 is likely that it has locked the registers, i.e., that the temperature limits
  87 cannot be changed.
  88
  89 Sysfs entries
  90 -------------
  91
  92 temp1_input             Temperature (RO)
  93 temp1_min               Minimum temperature (RO or RW)
  94 temp1_max               Maximum temperature (RO or RW)
  95 temp1_crit              Critical high temperature (RO or RW)
  96
  97 temp1_crit_hyst         Critical hysteresis temperature (RO or RW)
  98 temp1_max_hyst          Maximum hysteresis temperature (RO)
  99
 100 temp1_min_alarm         Temperature low alarm
 101 temp1_max_alarm         Temperature high alarm
 102 temp1_crit_alarm        Temperature critical alarm