Monku Monku - 9 months ago 64
Linux Question

How to read sysfs device path?

I have a USB touchscreen connected to my hardware setup. and when I use

cat /proc/bus/input/devices
I get the following details about my device:

I: Bus=0003 Vendor=2965 Product=5023 Version=0110
N: Name="Kortek Kortek Touch"
P: Phys=usb-0000:00:14.0-3.4/input2
S: Sysfs=/devices/pci0000:00/0000:00:14.0/usb3/3-3/3-3.4/3-3.4:1.2/0003:2965:5023.0006/input/input7
U: Uniq=S20131028
H: Handlers=mouse1 event7 js0
B: EV=1b
B: KEY=30000 0 0 0 0 0 0 0 0
B: ABS=3
B: MSC=10

I want to know what does the line
S: Sysfs=/devices/pci0000:00/0000:00:14.0/usb3/3-3/3-3.4/3-3.4:1.2/0003:2965:5023.0006/input/input7
means. How to read it ? What are the numbers in the path ?

Tim Tim

The Sysfs attribute is the location of that device within the sysfs filesystem. Assuming your kernel was compiled with CONFIG_SYSFS and the sysfs filesystem is mounted to /sys, you can view the device at:


To break down what path represents:

/sys/ is the mountpoint of the sysfs filesystem (see the output of mount | grep sysfs).

/devices/ contains a filesystem representation of the device tree (source).

/pci0000:00/ describes the PCI domain and the bus number. In this case, the domain number is 0000 and the bus number is 00 (source).

/0000:00:14.0/ has the the PCI domain and bus number repeated, along with the slot and function. In this case, the USB device's slot number is 14 and its function number is 0 (source).

/usb3/ refers to USB controller attached to bus number 3 (source).

/3-3/3-3.4/3-3.4:1.2/ has redundant information. The last /3-3.4:1.2/ means you are referring to the USB controller attached to bus 3, port 3, port 4, configuration number 1 and interface number 2 (source).

/0003:2965:5023.0006/ means the device is attached to bus 0003, has a vendor ID of 2965, and a product ID of 5023.