linux/Documentation/hwmon/adm1021
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   1Kernel driver adm1021
   2=====================
   3
   4Supported chips:
   5  * Analog Devices ADM1021
   6    Prefix: 'adm1021'
   7    Addresses scanned: I2C 0x18 - 0x1a, 0x29 - 0x2b, 0x4c - 0x4e
   8    Datasheet: Publicly available at the Analog Devices website
   9  * Analog Devices ADM1021A/ADM1023
  10    Prefix: 'adm1023'
  11    Addresses scanned: I2C 0x18 - 0x1a, 0x29 - 0x2b, 0x4c - 0x4e
  12    Datasheet: Publicly available at the Analog Devices website
  13  * Genesys Logic GL523SM
  14    Prefix: 'gl523sm'
  15    Addresses scanned: I2C 0x18 - 0x1a, 0x29 - 0x2b, 0x4c - 0x4e
  16    Datasheet:
  17  * Maxim MAX1617
  18    Prefix: 'max1617'
  19    Addresses scanned: I2C 0x18 - 0x1a, 0x29 - 0x2b, 0x4c - 0x4e
  20    Datasheet: Publicly available at the Maxim website
  21  * Maxim MAX1617A
  22    Prefix: 'max1617a'
  23    Addresses scanned: I2C 0x18 - 0x1a, 0x29 - 0x2b, 0x4c - 0x4e
  24    Datasheet: Publicly available at the Maxim website
  25  * National Semiconductor LM84
  26    Prefix: 'lm84'
  27    Addresses scanned: I2C 0x18 - 0x1a, 0x29 - 0x2b, 0x4c - 0x4e
  28    Datasheet: Publicly available at the National Semiconductor website
  29  * Philips NE1617
  30    Prefix: 'max1617' (probably detected as a max1617)
  31    Addresses scanned: I2C 0x18 - 0x1a, 0x29 - 0x2b, 0x4c - 0x4e
  32    Datasheet: Publicly available at the Philips website
  33  * Philips NE1617A
  34    Prefix: 'max1617' (probably detected as a max1617)
  35    Addresses scanned: I2C 0x18 - 0x1a, 0x29 - 0x2b, 0x4c - 0x4e
  36    Datasheet: Publicly available at the Philips website
  37  * TI THMC10
  38    Prefix: 'thmc10'
  39    Addresses scanned: I2C 0x18 - 0x1a, 0x29 - 0x2b, 0x4c - 0x4e
  40    Datasheet: Publicly available at the TI website
  41  * Onsemi MC1066
  42    Prefix: 'mc1066'
  43    Addresses scanned: I2C 0x18 - 0x1a, 0x29 - 0x2b, 0x4c - 0x4e
  44    Datasheet: Publicly available at the Onsemi website
  45
  46
  47Authors:
  48        Frodo Looijaard <frodol@dds.nl>,
  49        Philip Edelbrock <phil@netroedge.com>
  50
  51Module Parameters
  52-----------------
  53
  54* read_only: int
  55  Don't set any values, read only mode
  56
  57
  58Description
  59-----------
  60
  61The chips supported by this driver are very similar. The Maxim MAX1617 is
  62the oldest; it has the problem that it is not very well detectable. The
  63MAX1617A solves that. The ADM1021 is a straight clone of the MAX1617A.
  64Ditto for the THMC10. From here on, we will refer to all these chips as
  65ADM1021-clones.
  66
  67The ADM1021 and MAX1617A reports a die code, which is a sort of revision
  68code. This can help us pinpoint problems; it is not very useful
  69otherwise.
  70
  71ADM1021-clones implement two temperature sensors. One of them is internal,
  72and measures the temperature of the chip itself; the other is external and
  73is realised in the form of a transistor-like device. A special alarm
  74indicates whether the remote sensor is connected.
  75
  76Each sensor has its own low and high limits. When they are crossed, the
  77corresponding alarm is set and remains on as long as the temperature stays
  78out of range. Temperatures are measured in degrees Celsius. Measurements
  79are possible between -65 and +127 degrees, with a resolution of one degree.
  80
  81If an alarm triggers, it will remain triggered until the hardware register
  82is read at least once. This means that the cause for the alarm may already
  83have disappeared!
  84
  85This driver only updates its values each 1.5 seconds; reading it more often
  86will do no harm, but will return 'old' values. It is possible to make
  87ADM1021-clones do faster measurements, but there is really no good reason
  88for that.
  89
  90
  91Netburst-based Xeon support
  92---------------------------
  93
  94Some Xeon processors based on the Netburst (early Pentium 4, from 2001 to
  952003) microarchitecture had real MAX1617, ADM1021, or compatible chips
  96within them, with two temperature sensors. Other Xeon processors of this
  97era (with 400 MHz FSB) had chips with only one temperature sensor.
  98
  99If you have such an old Xeon, and you get two valid temperatures when
 100loading the adm1021 module, then things are good.
 101
 102If nothing happens when loading the adm1021 module, and you are certain
 103that your specific Xeon processor model includes compatible sensors, you
 104will have to explicitly instantiate the sensor chips from user-space. See
 105method 4 in Documentation/i2c/instantiating-devices. Possible slave
 106addresses are 0x18, 0x1a, 0x29, 0x2b, 0x4c, or 0x4e. It is likely that
 107only temp2 will be correct and temp1 will have to be ignored.
 108
 109Previous generations of the Xeon processor (based on Pentium II/III)
 110didn't have these sensors. Next generations of Xeon processors (533 MHz
 111FSB and faster) lost them, until the Core-based generation which
 112introduced integrated digital thermal sensors. These are supported by
 113the coretemp driver.
 114
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