Ubuntu Manpages

/proc/bus/

installed buses

/proc/bus/
Contains subdirectories for installed buses.
/proc/bus/pccard/
Subdirectory for PCMCIA devices when CONFIG_PCMCIA is set at kernel compilation time.
/proc/bus/pccard/drivers
/proc/bus/pci/
Contains various bus subdirectories and pseudo-files containing information about PCI buses, installed devices, and device drivers. Some of these files are not ASCII.
/proc/bus/pci/devices
Information about PCI devices. They may be accessed through lspci(8) and setpci(8).

proc(5)