(Phil) Added some ADM9240 documentation.

git-svn-id: http://lm-sensors.org/svn/lm-sensors/trunk@197 7894878c-1315-0410-8ee3-d5d059ff63e0

doc/chips/adm9240

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+This file documents the adm9240 directories for the Analog Devices
+ADM9240 hardware health monitoring chip found on some Intel mainboards
+(and others?).
+
+There will be one directory created for each detected ADM9240 chip.
+Each chip must be on the SMBus. Directories are called things
+like adm9240-i2c-1-2c. /proc/sys/dev/sensors/chips contains the SYSCTL
+values for all chip directories.
+
+Within each ADM9240 directory, you can find the following files:
+* alarms (ADM9240_SYSCTL_ALARMS)
+  A number which indicates which alarms are on. An alarm gets triggered when
+  some limit has been crossed. This number is composed from a 16 bit
+  value which is the combination of the Interrupt Status Register 1
+  (low byte) and 2 (high byte).
+  This file can not be written to.
+  The number is the logical OR of the following components (bit #
+  followed by a description):
+  
+0 +2.5 V_Error Read Only A "1" indicates a high or low limit has been exceeded.
+1 VCCP_Error Read Only A "1" indicates a high or low limit has been exceeded.
+2 +3.3 V_Error Read Only A "1" indicates a high or low limit has been exceeded.
+3 +5 V_Error Read Only A "1" indicates a high or low limit has been exceeded.
+4 Temp_Error Read Only A "1" indicates that a temperature interrupt has been set.
+5 Reserved Read Only Undefined.
+6 FAN1_Error Read Only A "1" indicates that a fan count limit has been exceeded.
+7 FAN2_Error Read Only A "1" indicates that a fan count limit has been exceeded.
+8 +12 V_Error Read Only A "1" indicates a high or low limit has been exceeded.
+9 VCCP2_Error Read Only A "1" indicates a high or low limit has been exceeded.
+10 Reserved Read Only Undefined.
+11 Reserved Read Only Undefined.
+12 Chassis_Error Read Only A "1" indicates chassis intrusion has gone high.
+13 Reserved Read Only Undefined.
+14 Reserved Read Only Undefined.
+15 Reserved Read Only Undefined.
+
+  If accessed through sysctl, this value is a long.
+* fan[1-3] (ADM9240_SYSCTL_FAN[1-2])
+  A list of two numbers. The first is the minimum fan rotation limit; the
+  second is the current fan rotation speed. Both are in RPM (rotations per
+  minute). An alarm is triggered if the rotation speed drops below the
+  limit. The first value can be changed. Not all RPM values can accurately
+  be represented, so some rounding is done.
+  If accessed through sysctl, this is a list of longs.
+* fan_div (LM78_SYSCTL_FAN_DIV)
+  A list of two numbers, one for each fan. Each number can be either 1, 2,
+  4 or 8. It is the internal scaling factor used for the FAN rotations. If
+  you change this number, the FAN readings get more or less detailed, but
+  the range in which they can be read too. Higher numbers give better 
+  resolution, but less range. The first two numbers can be changed, the
+  third not.
+  If accessed through sysctl, this is a list of longs.
+* 2.5V, Vccp1, 3.3V, 5V, 12V, and Vccp2 (ADM9240_SYSCTL_IN[0-5] in the
+order shown)
+  A list of three numbers. The first is the minimum limit, the second is the
+  maximum limit, and the third is the current value.  Note that
+  minimum means 'closest to zero'; so if the normal value equals -10, a
+  minimum could equal -9, and a maximum -11. Vccp1 and Vccp2 reflect core
+  voltages; they are by default set from the vid values, or set to 2.80V
+  if the vid lines seem to be unconnected. Not all voltage values
+  can be accurately represented, so some rounding is done.
+  The first two numbers can be changed, the third not.
+  If accessed through sysctl, this is a list of longs, each being the voltage
+  times 100.
+* temp
+  A list of three numbers. The first number is the Overtemperature Shutdown
+  value; the second is the Hysteris value and the third number is the
+  current value. The first two values can be modified. All values are in
+  degrees Celcius. An alarm is issued when the temperature first gets above
+  the Overtemperature Shutdown value; no more alarms are issued until the
+  temperature gets below the Hysteris value, at which moment another alarm
+  is issued, and the state is reset. A more useful behaviour can be found
+  by setting the Hysteris value to +127 degrees Celcius; in this case, 
+  alarms are issued during all the time when the actual temperature is 
+  above the Overtemperature Shutdown value.
+  The first two numbers can be changed, the third not.
+  If accessed through sysctl, this is a list of longs, each being the
+  temperature in degrees Celcius times 10.
+* vid
+  The core voltage value (the voltage level your processor should work with),
+  in volts. This is the value IN0 and IN1 are initialized to. If unconnected,
+  it usually reads 3.50V.
+  This number can not be changed.
+  If accessed through sysctl, this is a long, being the voltage times 100.
+* analog_out
+   This is feature is specific to the ADM9240.  It is a DAC voltage
+   control register for the Analog-Out pin.  Valid values are from 255
+   to 0 (with 255 being the highest voltage, and 0 the lowest).  From
+   the docs: "TheADM9240 has a single analog output from an unsigned
+   8-bit DAC which produces 0 V - 1.25 V."
+
+The data for each ADM9240 is updated each 1.5 seconds, but only if it is actually
+read.
+
+Note: Much of this documentation is copied from the LM78 documenation
+(the device from which most featuers of the ADM9240 is modelled from).
+The maintainer of the ADM9240 is Philip Edelbrock
+<phil@netroedge.com>; please forward corrections, suggestions, etc.
+to him.  For further technical information on this chip, I suggest
+getting the Acrobat PDF documentation from www.analog.com.