emcfan(4) - NetBSD Manual Pages

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EMCFAN(4)               NetBSD Kernel Interfaces Manual              EMCFAN(4)


NAME

     emcfan -- Driver for the Microchip Technology EMC210x and EMC230x fan
     controllers via I2C bus


SYNOPSIS

     emcfan* at iic? addr 0x2c
     emcfan* at iic? addr 0x2d
     emcfan* at iic? addr 0x2e
     emcfan* at iic? addr 0x2f
     emcfan* at iic? addr 0x4c
     emcfan* at iic? addr 0x4d


DESCRIPTION

     The emcfan driver supports the EMC210x family with the following models:
     EMC2101, EMC2101-R, EMC2103-1, EMC2103-2, EMC2103-4, EMC2104, and EMC2106
     and for the EMC230x family with the following models: EMC2301, EMC2302,
     EMC2303, and EMC2305.  All chips have one or more tachometers, and some
     of the chips have a number of temperature sensors and GPIO.  The emcfan
     driver provides envsys(4) framework measurements for the RPM as deter-
     mined by the tachometers.  If the chip has temperature sensors, the
     envsys(4) framework will provide an entry for every possible temperature
     sensor that a particular chip can support.  GPIO support is provided by
     gpio(4) framework and the pins can be accessed with the gpioctl(8) com-
     mand.

     The EMC fan controllers are arranged as a set of registers.  These regis-
     ters are accessed by a /dev device per attached chip.  The program
     emcfanctl(8) makes use of this device and allows all valid registers for
     particular chip to be read or written and provides some higher level com-
     mands that allow the drive level and frequency divider for a particular
     fan to be adjusted.


GPIO

     The EMC2103-2, EMC2103-4, EMC2104 and EMC2106 chips have gpio pins.  For
     the EMC2103-2 and EMC2103-4, these pins are only gpio and are not shared
     with any other function.  For the EMC2104 and EMC2106, the following is
     how the pins maps to the altN flags in the gpio(4) framework.

           box tab(:);
           ci | ci | ci
           = | = | =
           l | l | c
           - | - | -
           l | l | c
           - | - | -
           l | l | c
           - | - | -
           l | l | l
           - | - | -
           l | l | l
           - | - | -
           l | c | c.
           Pin:ALT0:ALT1
           GPIO1:CLK_IN:-
           GPIO2:TACH2:-
           GPIO3:PWM2:-
           GPIO4:OVERT2#:PWM3
           GPIO5:OVERT3#:PWM4
           GPIO6:-:-



SYSCTL VARIABLES

     The following sysctl(8) variables are provided:

     hw.emcfan0.debug  If the driver is compiled with EMCFAN_DEBUG, this node
                       will appear and can be used to set the debugging level.

     hw.emcfan0.poles<n>
                       For a number of the chips in the two chip families, the
                       tachometer calcuation algorithm needs to know the num-
                       ber of poles that the tachometer has in order to calcu-
                       late the RPM correctly.  Usually this will be 2, but if
                       the situation is otherwise, set this node to the number
                       of poles that the particular fan has.  The calculation
                       is also effected by the number of edges present in the
                       tachometer signal.  The number of edges is set with the
                       emcfanctl(8) command.

     hw.emcfan0.ftach  Many of the chips in the two famlies have a pin that
                       can be used to drive an alternative 32.767 kHz clock
                       for the tachometers.  The EMC2103-1, EMC2103-2 and
                       EMC2103-4 does not have this alternative clock pin, and
                       while it is likely that the chip is running at the
                       default 32.000 kHz, it might not be.  This variable
                       lets one set an alternative clock.  The units for this
                       node are in Hz.

     hw.emcfan0.vin4_temp_zone
                       The EMC2104 and EMC2106 have a special temperature sen-
                       sor pin called VIN4, if this sensor is wired up, then
                       this variable can be set to 1 and meaningful values
                       will appear in the envsys(4) framework.


FILES

     /dev/emcfanu                      The device unit u file.


SEE ALSO

     emcfanctl(8), envsys(4), iic(4), envstat(8), sysctl(8)


HISTORY

     The emcfan driver first appeared in NetBSD 11.0.


AUTHORS

     The emcfan driver was written by Brad Spencer <brad@anduin.eldar.org>.


BUGS

     The driver does not support the EMC2105 chip.

     While not exactly a bug, the driver does nothing with the alert inter-
     rupts that can be generated from many of the chips.  It would be more
     typical for this to be tied to a GPIO pin which can interrupt using CPU
     interrupts.

NetBSD 10.99                   Feburary 19, 2025                  NetBSD 10.99