You can not select more than 25 topics
Topics must start with a letter or number, can include dashes ('-') and can be up to 35 characters long.
93 lines
4.5 KiB
93 lines
4.5 KiB
Kernel driver adm1026
|
|
=====================
|
|
|
|
Supported chips:
|
|
* Analog Devices ADM1026
|
|
Prefix: 'adm1026'
|
|
Addresses scanned: I2C 0x2c, 0x2d, 0x2e
|
|
Datasheet: Publicly available at the Analog Devices website
|
|
http://www.analog.com/en/prod/0,,766_825_ADM1026,00.html
|
|
|
|
Authors:
|
|
Philip Pokorny <ppokorny@penguincomputing.com> for Penguin Computing
|
|
Justin Thiessen <jthiessen@penguincomputing.com>
|
|
|
|
Module Parameters
|
|
-----------------
|
|
|
|
* gpio_input: int array (min = 1, max = 17)
|
|
List of GPIO pins (0-16) to program as inputs
|
|
* gpio_output: int array (min = 1, max = 17)
|
|
List of GPIO pins (0-16) to program as outputs
|
|
* gpio_inverted: int array (min = 1, max = 17)
|
|
List of GPIO pins (0-16) to program as inverted
|
|
* gpio_normal: int array (min = 1, max = 17)
|
|
List of GPIO pins (0-16) to program as normal/non-inverted
|
|
* gpio_fan: int array (min = 1, max = 8)
|
|
List of GPIO pins (0-7) to program as fan tachs
|
|
|
|
|
|
Description
|
|
-----------
|
|
|
|
This driver implements support for the Analog Devices ADM1026. Analog
|
|
Devices calls it a "complete thermal system management controller."
|
|
|
|
The ADM1026 implements three (3) temperature sensors, 17 voltage sensors,
|
|
16 general purpose digital I/O lines, eight (8) fan speed sensors (8-bit),
|
|
an analog output and a PWM output along with limit, alarm and mask bits for
|
|
all of the above. There is even 8k bytes of EEPROM memory on chip.
|
|
|
|
Temperatures are measured in degrees Celsius. There are two external
|
|
sensor inputs and one internal sensor. Each sensor has a high and low
|
|
limit. If the limit is exceeded, an interrupt (#SMBALERT) can be
|
|
generated. The interrupts can be masked. In addition, there are over-temp
|
|
limits for each sensor. If this limit is exceeded, the #THERM output will
|
|
be asserted. The current temperature and limits have a resolution of 1
|
|
degree.
|
|
|
|
Fan rotation speeds are reported in RPM (rotations per minute) but measured
|
|
in counts of a 22.5kHz internal clock. Each fan has a high limit which
|
|
corresponds to a minimum fan speed. If the limit is exceeded, an interrupt
|
|
can be generated. Each fan can be programmed to divide the reference clock
|
|
by 1, 2, 4 or 8. Not all RPM values can accurately be represented, so some
|
|
rounding is done. With a divider of 8, the slowest measurable speed of a
|
|
two pulse per revolution fan is 661 RPM.
|
|
|
|
There are 17 voltage sensors. An alarm is triggered if the voltage has
|
|
crossed a programmable minimum or maximum limit. Note that minimum in this
|
|
case always means 'closest to zero'; this is important for negative voltage
|
|
measurements. Several inputs have integrated attenuators so they can measure
|
|
higher voltages directly. 3.3V, 5V, 12V, -12V and battery voltage all have
|
|
dedicated inputs. There are several inputs scaled to 0-3V full-scale range
|
|
for SCSI terminator power. The remaining inputs are not scaled and have
|
|
a 0-2.5V full-scale range. A 2.5V or 1.82V reference voltage is provided
|
|
for negative voltage measurements.
|
|
|
|
If an alarm triggers, it will remain triggered until the hardware register
|
|
is read at least once. This means that the cause for the alarm may already
|
|
have disappeared! Note that in the current implementation, all hardware
|
|
registers are read whenever any data is read (unless it is less than 2.0
|
|
seconds since the last update). This means that you can easily miss
|
|
once-only alarms.
|
|
|
|
The ADM1026 measures continuously. Analog inputs are measured about 4
|
|
times a second. Fan speed measurement time depends on fan speed and
|
|
divisor. It can take as long as 1.5 seconds to measure all fan speeds.
|
|
|
|
The ADM1026 has the ability to automatically control fan speed based on the
|
|
temperature sensor inputs. Both the PWM output and the DAC output can be
|
|
used to control fan speed. Usually only one of these two outputs will be
|
|
used. Write the minimum PWM or DAC value to the appropriate control
|
|
register. Then set the low temperature limit in the tmin values for each
|
|
temperature sensor. The range of control is fixed at 20 °C, and the
|
|
largest difference between current and tmin of the temperature sensors sets
|
|
the control output. See the datasheet for several example circuits for
|
|
controlling fan speed with the PWM and DAC outputs. The fan speed sensors
|
|
do not have PWM compensation, so it is probably best to control the fan
|
|
voltage from the power lead rather than on the ground lead.
|
|
|
|
The datasheet shows an example application with VID signals attached to
|
|
GPIO lines. Unfortunately, the chip may not be connected to the VID lines
|
|
in this way. The driver assumes that the chips *is* connected this way to
|
|
get a VID voltage.
|
|
|