sysfs

Mounted at /sys
It's a filesystem that allows kernel subsystems to report kernel objects, object attributes, and object relationships to user space
It's always mounted to /sys at the system startup (before fstab is read)

mount | grep sysfs

devices

Every hardware attached to the computer
E.g., /sys/devices/pci0000:00/0000:00:00.0

block

Devices that are storage
Usually link files that point to devices

bus

/sys/bus/pci/devices/: all pci devices
Actually points to /sys/devices/pci0000:00/
GPU
/sys/bus/pci/devices/0000:03:00.0
/sys/bus/pci/devices/0000:03:00.0/boot_vga: whether the GPU will be used for booting (1 or 0)
/sys/bus/pci/devices/0000:03:00.0/current_link_speed: PCI speed
/sys/bus/pci/devices/0000:03:00.0/driver: example: amdgpu

set -u
for boot_vga in /sys/bus/pci/devices/*/boot_vga; do
  echo "Found vga device: ${boot_vga}"
  if [ $(<"${boot_vga}") -eq 0 ]; then
    echo "Found Boot VGA Device - false: ${boot_vga}"

    dir=$(dirname -- "${boot_vga}")
    for dev in "${dir::-1}"*; do
      echo "Devices: ${dev}"
      # echo 'vfio-pci' > "${dev}/driver_override"
    done
  else
    echo "Found Boot VGA Device - true: ${boot_vga}"
  fi
done

for f in /sys/bus/pci/devices/*/boot_vga ; do echo -n "$f:" ; cat $f ; done

class

leds

/sys/class/leds/:white:kbd_backlight/brightness

backlight

/sys/class/backlight/gmux_backlight/brightness

#!/bin/python
import subprocess
import json
import sys


def backlight_devices():
    devices_output = subprocess.check_output(
        "brightnessctl -l -m -c backlight",
        shell=True,
        encoding='utf-8',
    )

    backlight_devices = []

    for device in devices_output.splitlines():
        device_id = device.split(",")[0]

        # device_name = subprocess.check_output(
        #     "cat /sys/class/backlight/" + device_id +
        #     "/device/idModel" + "|| echo " + device_id,
        #     shell=True,
        #     encoding='utf-8',
        # ).strip()

        device_brightness_percentage = device.split(",")[3].replace("%", "")

        backlight_devices.append(
            {
                "id": device_id,
                # "name": device_name,
                "brightness_percentage": device_brightness_percentage
            })

    return backlight_devices
sys.stdout.write(json.dumps(backlight_devices()))

drm

/sys/class/drm/card2-DP-8/enabled

for p in /sys/class/drm/*/status; do
  con=${p%/status}
  echo -n "${con#*/card?-}: "
  cat $p
done

cat /sys/class/drm/card?-*/enabled

power_supply

/sys/class/power_supply/BAT0

+++ Battery Care
Plugin: generic
Supported features: none available

+++ Battery Status: BAT0
/sys/class/power_supply/BAT0/manufacturer                   = DSY
/sys/class/power_supply/BAT0/model_name                     = bq40z651
/sys/class/power_supply/BAT0/cycle_count                    =    229
/sys/class/power_supply/BAT0/charge_full_design             =   8790 [mAh]
/sys/class/power_supply/BAT0/charge_full                    =   7155 [mAh]
/sys/class/power_supply/BAT0/charge_now                     =   6986 [mAh]
/sys/class/power_supply/BAT0/current_now                    =      0 [mA]
/sys/class/power_supply/BAT0/status                         = Full

/sys/class/power_supply/BAT0/charge_control_start_threshold = (not available)
/sys/class/power_supply/BAT0/charge_control_end_threshold   = (not available)

Charge                                                      =   97.6 [%]
Capacity                                                    =   81.4 [%]