ADM1275

ADM1275/ADM1281/ADM1294 Digital Power Monitor and Hot Swap Controller Linux Driver.

Supported Devices

• ADM1075

• ADM1272

• ADM1275

• ADM1276

• ADM1278

• ADM1281

• ADM1293

• ADM1294

Evaluation Boards

• EVAL-ADM1076

• EVAL-ADM1273

• EVAL-ADM1276

• EVAL-ADM1277

• EVAL-ADM1279

• EVAL-ADM1282

• EVAL-ADM1294

• EVAL-ADM1295

Description

The ADM1293 and ADM1294 are high accuracy integrated digital power monitors that offer digital current, voltage, and power monitoring using an on-chip, 12-bit analog-to-digital converter (ADC), communicated through a PMBus compliant I2C interface.

The PMBus Core Driver provides a common driver for PMBus compliant devices. The adm1275 Linux driver is built on top of this core driver and provides adm1xxx specific functions and attributes on top of the ones provided by the core.

Other PMBus related references include, but not limited to, the following:

PMBus Core API

PMBus Source

PMBus Header

PMBus Documentation

Source Code

Status

Source	Mainlined?
drivers/hwmon/pmbus/adm1275.c	yes

Files

Function	File
driver	drivers/hwmon/pmbus/adm1275.c

Example I2C device initialization

The ADM1xxx uses an I2C interface. Currently, the devices can only be instantiated via device tree.

Required devicetree properties:

• compatible: Must be always one of these:

  • adi,adm1075

  • adi,adm1271

  • adi,adm1272

  • adi,adm1275

  • adi,adm1278

  • adi,adm1281

  • adi,adm1293

  • adi,adm1294

• reg: Must be either the I2C device address (refer to device datasheet address table).

Example I2C:

&i2c0 {
        #address-cells = <1>;
        #size-cells = <0>;
        status = "okay";
        adm1281: adm1281@10 {
                compatible = "adi,adm1281";
                reg = <0x10>;
        };
};

For more supported devicetree properties take a look to dt-bindings.

Enabling Linux driver support

Configure kernel with make menuconfig (alternatively use make xconfig or make qconfig). .. note:

The ADM1xxxx I2C driver depends on **CONFIG_I2C**, **SENSORS_PMBUS**, and on **SENSORS_ADM1275**.

Adding Linux driver support

Configure kernel with make menuconfig (alternatively use make xconfig or make qconfig)

Linux Kernel Configuration
    Device Drivers  --->
        <*>     Hardware Monitoring support --->
            --- Hardware Monitoring support
        [--snip--]
            <*> Analog Devices ADM1275 Digital Power Monitor and Hot Swap Controller over I2C
        [--snip--]

Hardware configuration

Driver testing

HWMON device files

Each and every HWMON device has a device folder under /sys/class/hwmon/hwmonX, where X is the hwmon device index. Under every of these directory folders there are a set of files, depending on what kind of hardware monitoring is supported (temperature, voltage). In order to determine which hwmon device corresponds to which hardware chip, the user can read the name file under /sys/class/hwmon/hwmonX/name.

root@raspberrypi:/home/embedded3/Desktop/joram/adm1281# cd /sys/class/hwmon/
root@raspberrypi:/sys/class/hwmon# ls
hwmon0  hwmon1  hwmon2

root@raspberrypi:/sys/class/hwmon# cd hwmon2

root@raspberrypi:/sys/class/hwmon/hwmon2# ls -l
total 0
-rw-r--r-- 1 root root 4096 May  8 03:48 curr1_highest
-r--r--r-- 1 root root 4096 May  8 03:48 curr1_input
-r--r--r-- 1 root root 4096 May  8 03:48 curr1_label
-rw-r--r-- 1 root root 4096 May  8 03:48 curr1_max
-r--r--r-- 1 root root 4096 May  8 03:48 curr1_max_alarm
-rw-r--r-- 1 root root 4096 May  8 03:48 curr1_reset_history
-rw-r--r-- 1 root root 4096 May  8 03:48 curr_samples
lrwxrwxrwx 1 root root    0 May  8 03:48 device -> ../../../1-0010
-rw-r--r-- 1 root root 4096 May  8 03:48 in1_highest
-r--r--r-- 1 root root 4096 May  8 03:48 in1_input
-r--r--r-- 1 root root 4096 May  8 03:48 in1_label
-rw-r--r-- 1 root root 4096 May  8 03:48 in1_max
-r--r--r-- 1 root root 4096 May  8 03:48 in1_max_alarm
-rw-r--r-- 1 root root 4096 May  8 03:48 in1_min
-r--r--r-- 1 root root 4096 May  8 03:48 in1_min_alarm
-rw-r--r-- 1 root root 4096 May  8 03:48 in1_reset_history
-rw-r--r-- 1 root root 4096 May  8 03:48 in2_highest
-r--r--r-- 1 root root 4096 May  8 03:48 in2_input
-r--r--r-- 1 root root 4096 May  8 03:48 in2_label
-rw-r--r-- 1 root root 4096 May  8 03:48 in2_max
-r--r--r-- 1 root root 4096 May  8 03:48 in2_max_alarm
-rw-r--r-- 1 root root 4096 May  8 03:48 in2_min
-r--r--r-- 1 root root 4096 May  8 03:48 in2_min_alarm
-rw-r--r-- 1 root root 4096 May  8 03:48 in2_reset_history
-rw-r--r-- 1 root root 4096 May  8 03:48 in_samples
-r--r--r-- 1 root root 4096 May  8 03:46 name
lrwxrwxrwx 1 root root    0 May  8 03:48 of_node -> ../../../../../../../../firmware/devicetree/base/soc/i2c@7e804000/adm1281@10
drwxr-xr-x 2 root root    0 May  8 03:48 power
-r--r--r-- 1 root root 4096 May  8 03:48 power1_alarm
-r--r--r-- 1 root root 4096 May  8 03:48 power1_input
-rw-r--r-- 1 root root 4096 May  8 03:48 power1_input_highest
-r--r--r-- 1 root root 4096 May  8 03:48 power1_label
-rw-r--r-- 1 root root 4096 May  8 03:48 power1_max
-rw-r--r-- 1 root root 4096 May  8 03:48 power1_reset_history
-rw-r--r-- 1 root root 4096 May  8 03:48 power_samples
lrwxrwxrwx 1 root root    0 May  8 03:48 subsystem -> ../../../../../../../../class/hwmon
-rw-r--r-- 1 root root 4096 May  8 03:48 temp1_crit
-r--r--r-- 1 root root 4096 May  8 03:48 temp1_crit_alarm
-rw-r--r-- 1 root root 4096 May  8 03:48 temp1_highest
-r--r--r-- 1 root root 4096 May  8 03:48 temp1_input
-rw-r--r-- 1 root root 4096 May  8 03:48 temp1_max
-r--r--r-- 1 root root 4096 May  8 03:48 temp1_max_alarm
-rw-r--r-- 1 root root 4096 May  8 03:48 temp1_reset_history
-rw-r--r-- 1 root root 4096 May  8 03:38 uevent
root@raspberrypi:/sys/class/hwmon/hwmon2#

For each type of monitored value (current, power), the file will look like ${type}_${monitored_value}_${channel}, where ${monitored_value} can be the current value, the high threshold, etc… The channel is the index when, for example, a device can monitor more than one voltage. For more information on the files format, take a look to sysfs-interface.

Show device name

root@raspberrypi:/sys/class/hwmon/hwmon2# cat name
adm1281

Show current values

The device supports readings of current, voltage, power, temperature and energy. To get, for example, the value of the monitored voltage:

root@raspberrypi:/sys/class/hwmon/hwmon2# cat in1_input
15199

Show highest read value

root@raspberrypi:/sys/class/hwmon/hwmon2# cat in1_highest
15199

Show high threshold

root@raspberrypi:/sys/class/hwmon/hwmon2# cat in1_max
20893

Show low threshold

root@raspberrypi:/sys/class/hwmon/hwmon2# cat in1_min
0

Show high threshold alarm

root@raspberrypi:/sys/class/hwmon/hwmon2# cat in1_max_alarm
0

Show low threshold alarm

root@raspberrypi:/sys/class/hwmon/hwmon2# cat in1_min_alarm
0

Show label

Some channels, support a label attribute which specifies the name of the channel being monitored.

root@raspberrypi:/sys/class/hwmon/hwmon2# cat in1_label
vin

Set High threshold

root@raspberrypi:/sys/class/hwmon/hwmon2# echo 20206 > in1_max
root@raspberrypi:/sys/class/hwmon/hwmon2# cat in1_max
20205
root@raspberrypi:/sys/class/hwmon/hwmon2#

Set Low threshold

root@raspberrypi:/sys/class/hwmon/hwmon2# echo 3341 > in1_min
root@raspberrypi:/sys/class/hwmon/hwmon2# cat in1_min
3342
root@raspberrypi:/sys/class/hwmon/hwmon2#

Reset History

root@raspberrypi:/sys/class/hwmon/hwmon2# cat in1_reset_history
0
root@raspberrypi:/sys/class/hwmon/hwmon2# echo 1 > in1_reset_history
root@raspberrypi:/sys/class/hwmon/hwmon2# cat in1_reset_history
0
root@raspberrypi:/sys/class/hwmon/hwmon2#

More Information

HWMON pointers

• HWMON mailing list: linux-hwmon@vger.kernel.org

• HWMON Linux Kernel Documentation

• HWMON sysfs-interface

Need Help?

• Analog Devices Linux Device Drivers Help Forum