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EMCFAN(4) Device Drivers 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
determined 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)
command.
The EMC fan controllers are arranged as a set of registers. These
registers 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
commands 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.
+------+---------+------+
| 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
number of poles that the tachometer has in order to
calculate 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
sensor 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
interrupts 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 11.99 Feburary 19, 2025 NetBSD 11.99