first cut at documenting naming and content standards for

entries in /proc. Corrections/additions welcome.


git-svn-id: http://lm-sensors.org/svn/lm-sensors/trunk@971 7894878c-1315-0410-8ee3-d5d059ff63e0

doc/developers/proc

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+Naming and data standards under /proc
+-------------------------------------
+
+The libsensors library offers an interface to the raw sensors data
+through the sysctl interface. See the 'sysctl' file and the libsensors
+source for further information.
+
+An alternative method that some programs use is to access the /proc
+files directly. This document briefly describes the standards that
+the drivers follow, so that a program can access this data in a consistent way.
+
+Note that not all chip drivers adhere to this standard.
+We will attempt to migrate older drivers to this standard,
+and ensure that new drivers follow this standard.
+
+As each chip gets its own directory under /proc/sys/dev/sensors.
+The format is either chip-i2c-bus-hexaddress or chip-isa-hexaddress.
+(Exception - chip lm78-j has a '-' in it - should this be changed??)
+
+/proc entries are as follows:
+
+
+Entry	Values	Function
+-----	------	--------
+alarms	  1	Alarm bitmask.
+		Read only.
+		Integer representation of one, two, or three bytes.
+		A '1' bit means an alarm.
+		Generally a straight representation of a chips' internal
+		alarm registers; no standard.
+
+beep	  2     Beep or interrupt bitmask.
+		Same format as 'alarms' with same bit locations.
+		
+fan[1-3]  2	Fan min and input value.
+		Two integers indicating RPM.
+		First value is read/write and second is read only.
+
+fan_div	  3	Fan divisor.
+		Integers in powers of two (1,2,4,8,16,32,64,128).
+		Some chips only support values 1,2,4,8.
+		Entries correspond to the fans[1-3].
+
+in[0-8]   3	Voltage min, max, and input value.
+		Floating point values X.XX in volts from 0 to 4.01 volts.
+		Actual voltage depends on the scaling resistors on the motherboard,
+		as recommended in the chip datasheet.
+		This varies by chip and by motherboard.
+		Because of this variation, values are generally NOT scaled
+		by the chip driver, and must be done by the application.
+		However, some drivers do scale, with various success.
+		First two values are read/write and third is read only.
+		Typical usage:
+			in0	CPU #1 voltage (not scaled)
+			in1	CPU #1 voltage (not scaled)
+			in2	3.3V nominal (not scaled)
+			in3	5.0V nominal (scaled)
+			in4	12.0V nominal (scaled)
+			in5	-12.0V nominal (scaled)
+			in6	-5.0V nominal (scaled)
+			in7	varies
+			in8	varies
+
+pwm[1-3]   1	Pulse width modulation fan control.
+		Integer 0 - 255, read/write.
+		Corresponds to the fans 1-3.
+
+sensor[1-3]  1	Sensor type selection.
+		Integers 1,2,3, or thermistor Beta value (3435); read/write.
+
+temp,
+temp[1-3]  3	Temperature max, min or hysteresis, and input value.
+	       	Floating point values XXX.X or XXX.XX in degrees Celcius.
+		'temp' is used if there is only one temperature sensor on the chip.
+		Temp1 is generally the sensor inside the chip itself,
+		generally reported as "motherboard temperature".
+		temp2 and temp3 are generally external sensors, 
+		the thermal diode inside the CPU, generally reported as
+		"CPU temperature".
+
+vid	   1	CPU core voltage.
+		Read only.
+		Floating point X.XX corresponding to CPU core voltage as
+		told to the sensor chip. Not always correct.
+		Possible values are 1.30 - 2.05 in 0.05 increments
+		or 2.1 - 3.5 in 0.1 increments.