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DBCOOL(4)			   BSD Kernel Interfaces Manual 			DBCOOL(4)

NAME
     dbcool, adm1027, adm1030, adm1031, adt7463, adt7466, adt7467, adt7468, adt7473, adt7475,
     adt7476, adt7490, emc6d103s -- dbCool(tm) family of environmental monitors and fan con-
     trollers

SYNOPSIS
     dbcool* at ki2c?
     dbcool* at iic? addr 0x2e

DESCRIPTION
     The dbcool driver provides support for the Analog Devices dbCool and the SMSC EMC6D103S
     environmental monitor chips to be used with the envsys(4) API.

     These chips support up to fifteen sensors.  Not all of the following sensors are supported
     on all chips.

	   Sensor    Units    Typical Use
	   l_temp    uK       local chip temperature
	   r1_temp   uK       CPU temperature
	   r2_temp   uK       GPU temperature
	   Vccp      uV DC    CPU Vcore
	   Vcc	     uV DC    Chip's supply voltage
	   2.5V      uV DC    2.5V supply
	   5V	     uV DC    5V supply
	   12V	     uV DC    12V supply
	   Vtt	     uV DC    PECI ref. voltage (2.25V ref, ADT7490 only)
	   Imon      uV DC    Current monitor (2.25V ref, ADT7490 only)
	   AIN1      uV DC    Analog In (2.25V ref, ADT7466 only)
	   AIN2      uV DC    Analog In (2.25V ref, ADT7466 only)
	   fan1      RPM      Chassis Fan
	   fan2      RPM      Chassis Fan
	   fan3      RPM      Chassis Fan
	   fan4      RPM      Chassis Fan
	   VID	     (none)   CPU VID code (selected chips only)

     Each temperature and voltage sensor has programmable hardware high- and low-limits; fan sen-
     sors have only a low-limit.  These limits can be set using the envstat(8) utility.  Due to
     hardware limitations, the minimum permissible value for the fan speed low-limits is 83 RPM.

     Temperature sensors also have Tmin, Trange, Thyst, and Ttherm sysctl(8) variables; these
     values are used by the fan speed controllers.  Their values are in units of degC, since this
     is the unit which is programmed into the device registers.

     All members of the dbCool family support Pulse-Width Modulated (PWM) fan speed control based
     on temperature thresholds - the fan will spin up when its associated thermal sensor(s)
     exceeds its configured Tmin value.  The fan will go faster as the temperature rises, and
     will slow down as the temperature falls.  If the temperature exceeds the sensor's Ttherm
     value, the THERM signal will be asserted, and if enabled the fan will run at full speed.
     The fan will be turned off when the sensor(s) that triggered it reports a temperature which
     is at least Thyst degrees below its Tmin threshold.

     Each fan controller is programmable using the following sysctl(8) variables.

	   hw.dbcool0.fan_ctl_0.behavior
	   hw.dbcool0.fan_ctl_0.min_duty
	   hw.dbcool0.fan_ctl_0.max_duty
	   hw.dbcool0.fan_ctl_0.cur_duty

     The behavior variable controls the selection of temperature sensors associated with the fan
     controller.  When the associated temperature sensor reaches its Tmin value, the fan con-
     troller starts the fan at its minimum duty cycle; when the associated temperature sensor
     reaches its Ttherm value and asserts the THERM signal (or if an external THERM signal is
     asserted), the fan controller sets the fan speed to a 100% duty cycle.  Between these two
     settings, each temperature sensor is used to calculate a duty cycle linearly based on the
     slope defined by the temperature sensor's range variable.	When the associated temperature
     falls at least Thyst degress below its Tmin value, the fan controller will turn off the fan.
     (On the ADM1030, the value for Thyst is fixed at 5 degC.)

     Valid values for the behavior variable are:

	   local	   (not available on ADM1030)
	   remote1
	   remote2	   (not available on ADM1030)
	   local+remote2   (not available on ADM1030)
	   all-temps
	   full-speed	   (not available on ADM1030)
	   manual
	   disabled

     When the behavior variable is set to ``manual'', the cur-duty variable becomes user-writable
     and can be set to any value between 0 and 100 inclusive to control the fan's duty cycle man-
     ually.  In all other behavior modes, the cur-duty variable is read-only and updates are
     ignored.

     The min-duty and max-duty variables define the range over which the fan controller will man-
     age the fan's duty cycle.	On the ADM1030, these values are not separately controllable.
     The max-duty is fixed at 100%, and the cur-duty variable is used to specify the minimum duty
     cycle when the fan controller is running in automatic mode.

     Note that the duty-cycle value does not directly correspond to the fan's speed.  That is, a
     33% duty cycle does not mean that the fan runs at 33% of its maximum speed; in actuality, a
     33% duty cycle drives the fan at a speed close to 50% of its maximum.  Fan speed correlates
     approximately to the square root of the duty cycle.

EXAMPLES
     The envstat(8) utility can be used to determine the sensors supported:

		       Current	CritMax  WarnMax  WarnMin  CritMin Unit
	    l_temp:	44.250					   degC
	   r1_temp:	41.250					   degC
	   r2_temp:	   N/A
	      Vccp:	 0.002					   V
	       Vcc:	 3.351					   V
	      fan1:	   N/A
	      fan2:	   N/A
	      fan3:	   N/A
	      fan4:	   N/A

     Using this information, the following commands in /etc/envsys.conf will set appropriate lim-
     its for CPU temperature and chip supply voltage, and powerd will be notified if the limits
     are exceeded:

	   dbcool0 {
		   sensor1 {
			   warning-max	= 60C;
			   critical-max = 65C;
		   }
		   sensor4 {
			   critical-min = 3.1;
			   warning-min =  3.2;
			   critical-max = 3.5;
		   }
	   }

SEE ALSO
     envsys(4), iic(4), envstat(8), powerd(8), sysctl(8)

HISTORY
     The dbcool device appeared in NetBSD 5.0.

BUGS
     Although the sensor limit registers can be programmed, there is currently no use of the
     dbCool chips' ability to generate an SMBus interrupt when the limits are exceeded.  Limit
     checking and event generation are done in software, and are performed only when the sensor
     values are polled and refreshed.

     The ADT7466 chip, although officially a member of the dbCool family, is programmed quite
     differently.  The fan controllers on this chip are not currently implemented.

     The PECI (Processor Environment Control Interface) temperature sensors and the associated
     PWM behavior modes on the ADT7490 are not currently supported.

BSD					  March 12, 2011				      BSD
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