Documentation/hwmon/jc42.rst

   1 Kernel driver jc42
   2 ==================
   3
   4 Supported chips:
   5
   6   * Analog Devices ADT7408
   7
   8     Datasheets:
   9
  10         http://www.analog.com/static/imported-files/data_sheets/ADT7408.pdf
  11
  12   * Atmel AT30TS00, AT30TS002A/B, AT30TSE004A
  13
  14     Datasheets:
  15
  16         http://www.atmel.com/Images/doc8585.pdf
  17
  18         http://www.atmel.com/Images/doc8711.pdf
  19
  20         http://www.atmel.com/Images/Atmel-8852-SEEPROM-AT30TSE002A-Datasheet.pdf
  21
  22         http://www.atmel.com/Images/Atmel-8868-DTS-AT30TSE004A-Datasheet.pdf
  23
  24   * IDT TSE2002B3, TSE2002GB2, TSE2004GB2, TS3000B3, TS3000GB0, TS3000GB2,
  25
  26         TS3001GB2
  27
  28     Datasheets:
  29
  30         Available from IDT web site
  31
  32   * Maxim MAX6604
  33
  34     Datasheets:
  35
  36         http://datasheets.maxim-ic.com/en/ds/MAX6604.pdf
  37
  38   * Microchip MCP9804, MCP9805, MCP9808, MCP98242, MCP98243, MCP98244, MCP9843
  39
  40     Datasheets:
  41
  42         http://ww1.microchip.com/downloads/en/DeviceDoc/22203C.pdf
  43
  44         http://ww1.microchip.com/downloads/en/DeviceDoc/21977b.pdf
  45
  46         http://ww1.microchip.com/downloads/en/DeviceDoc/25095A.pdf
  47
  48         http://ww1.microchip.com/downloads/en/DeviceDoc/21996a.pdf
  49
  50         http://ww1.microchip.com/downloads/en/DeviceDoc/22153c.pdf
  51
  52         http://ww1.microchip.com/downloads/en/DeviceDoc/22327A.pdf
  53
  54   * NXP Semiconductors SE97, SE97B, SE98, SE98A
  55
  56     Datasheets:
  57
  58         http://www.nxp.com/documents/data_sheet/SE97.pdf
  59
  60         http://www.nxp.com/documents/data_sheet/SE97B.pdf
  61
  62         http://www.nxp.com/documents/data_sheet/SE98.pdf
  63
  64         http://www.nxp.com/documents/data_sheet/SE98A.pdf
  65
  66   * ON Semiconductor CAT34TS02, CAT6095
  67
  68     Datasheet:
  69
  70         http://www.onsemi.com/pub_link/Collateral/CAT34TS02-D.PDF
  71
  72         http://www.onsemi.com/pub/Collateral/CAT6095-D.PDF
  73
  74   * ST Microelectronics STTS424, STTS424E02, STTS2002, STTS2004, STTS3000
  75
  76     Datasheets:
  77
  78         http://www.st.com/web/en/resource/technical/document/datasheet/CD00157556.pdf
  79
  80         http://www.st.com/web/en/resource/technical/document/datasheet/CD00157558.pdf
  81
  82         http://www.st.com/web/en/resource/technical/document/datasheet/CD00266638.pdf
  83
  84         http://www.st.com/web/en/resource/technical/document/datasheet/CD00225278.pdf
  85
  86         http://www.st.com/web/en/resource/technical/document/datasheet/DM00076709.pdf
  87
  88   * JEDEC JC 42.4 compliant temperature sensor chips
  89
  90     Datasheet:
  91
  92         http://www.jedec.org/sites/default/files/docs/4_01_04R19.pdf
  93
  94
  95   Common for all chips:
  96
  97     Prefix: 'jc42'
  98
  99     Addresses scanned: I2C 0x18 - 0x1f
 100
 101 Author:
 102         Guenter Roeck <linux@roeck-us.net>
 103
 104
 105 Description
 106 -----------
 107
 108 This driver implements support for JEDEC JC 42.4 compliant temperature sensors,
 109 which are used on many DDR3 memory modules for mobile devices and servers. Some
 110 systems use the sensor to prevent memory overheating by automatically throttling
 111 the memory controller.
 112
 113 The driver auto-detects the chips listed above, but can be manually instantiated
 114 to support other JC 42.4 compliant chips.
 115
 116 Example: the following will load the driver for a generic JC 42.4 compliant
 117 temperature sensor at address 0x18 on I2C bus #1::
 118
 119         # modprobe jc42
 120         # echo jc42 0x18 > /sys/bus/i2c/devices/i2c-1/new_device
 121
 122 A JC 42.4 compliant chip supports a single temperature sensor. Minimum, maximum,
 123 and critical temperature can be configured. There are alarms for high, low,
 124 and critical thresholds.
 125
 126 There is also an hysteresis to control the thresholds for resetting alarms.
 127 Per JC 42.4 specification, the hysteresis threshold can be configured to 0, 1.5,
 128 3.0, and 6.0 degrees C. Configured hysteresis values will be rounded to those
 129 limits. The chip supports only a single register to configure the hysteresis,
 130 which applies to all limits. This register can be written by writing into
 131 temp1_crit_hyst. Other hysteresis attributes are read-only.
 132
 133 If the BIOS has configured the sensor for automatic temperature management, it
 134 is likely that it has locked the registers, i.e., that the temperature limits
 135 cannot be changed.
 136
 137 Sysfs entries
 138 -------------
 139
 140 ======================= ===========================================
 141 temp1_input             Temperature (RO)
 142 temp1_min               Minimum temperature (RO or RW)
 143 temp1_max               Maximum temperature (RO or RW)
 144 temp1_crit              Critical high temperature (RO or RW)
 145
 146 temp1_crit_hyst         Critical hysteresis temperature (RO or RW)
 147 temp1_max_hyst          Maximum hysteresis temperature (RO)
 148
 149 temp1_min_alarm         Temperature low alarm
 150 temp1_max_alarm         Temperature high alarm
 151 temp1_crit_alarm        Temperature critical alarm
 152 ======================= ===========================================