linux/Documentation/hwmon/gl518sm
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   1Kernel driver gl518sm
   2=====================
   3
   4Supported chips:
   5  * Genesys Logic GL518SM release 0x00
   6    Prefix: 'gl518sm'
   7    Addresses scanned: I2C 0x2c and 0x2d
   8    Datasheet: http://www.genesyslogic.com/pdf
   9  * Genesys Logic GL518SM release 0x80
  10    Prefix: 'gl518sm'
  11    Addresses scanned: I2C 0x2c and 0x2d
  12    Datasheet: http://www.genesyslogic.com/pdf
  13
  14Authors:
  15        Frodo Looijaard <frodol@dds.nl>,
  16        Ky\xC3\xB6sti M\xC3\xA4lkki <kmalkki@cc.hut.fi>
  17        Hong-Gunn Chew <hglinux@gunnet.org>
  18        Jean Delvare <khali@linux-fr.org>
  19
  20Description
  21-----------
  22
  23IMPORTANT:
  24
  25For the revision 0x00 chip, the in0, in1, and in2  values (+5V, +3V,
  26and +12V) CANNOT be read. This is a limitation of the chip, not the driver.
  27
  28This driver supports the Genesys Logic GL518SM chip. There are at least
  29two revision of this chip, which we call revision 0x00 and 0x80. Revision
  300x80 chips support the reading of all voltages and revision 0x00 only
  31for VIN3.
  32
  33The GL518SM implements one temperature sensor, two fan rotation speed
  34sensors, and four voltage sensors. It can report alarms through the
  35computer speakers.
  36
  37Temperatures are measured in degrees Celsius. An alarm goes off while the
  38temperature is above the over temperature limit, and has not yet dropped
  39below the hysteresis limit. The alarm always reflects the current
  40situation. Measurements are guaranteed between -10 degrees and +110
  41degrees, with a accuracy of +/-3 degrees.
  42
  43Rotation speeds are reported in RPM (rotations per minute). An alarm is
  44triggered if the rotation speed has dropped below a programmable limit. In
  45case when you have selected to turn fan1 off, no fan1 alarm is triggered.
  46
  47Fan readings can be divided by a programmable divider (1, 2, 4 or 8) to
  48give the readings more range or accuracy.  Not all RPM values can
  49accurately be represented, so some rounding is done. With a divider
  50of 2, the lowest representable value is around 1900 RPM.
  51
  52Voltage sensors (also known as VIN sensors) report their values in volts.
  53An alarm is triggered if the voltage has crossed a programmable minimum or
  54maximum limit. Note that minimum in this case always means 'closest to
  55zero'; this is important for negative voltage measurements. The VDD input
  56measures voltages between 0.000 and 5.865 volt, with a resolution of 0.023
  57volt. The other inputs measure voltages between 0.000 and 4.845 volt, with
  58a resolution of 0.019 volt. Note that revision 0x00 chips do not support
  59reading the current voltage of any input except for VIN3; limit setting and
  60alarms work fine, though.
  61
  62When an alarm is triggered, you can be warned by a beeping signal through your
  63computer speaker. It is possible to enable all beeping globally, or only the
  64beeping for some alarms.
  65
  66If an alarm triggers, it will remain triggered until the hardware register
  67is read at least once (except for temperature alarms). This means that the
  68cause for the alarm may already have disappeared! Note that in the current
  69implementation, all hardware registers are read whenever any data is read
  70(unless it is less than 1.5 seconds since the last update). This means that
  71you can easily miss once-only alarms.
  72
  73The GL518SM only updates its values each 1.5 seconds; reading it more often
  74will do no harm, but will return 'old' values.
  75