Mine

~$ ls -l /sys/class/
cpuid/        i2c-adapter/  net/          scsi_generic/ spi_master/   usb_host/
drm/          input/        pci_bus/      scsi_host/    tty/          vc/
graphics/     mem/          printer/      scsi_tape/    usb/
hwmon/        misc/         scsi_device/  sound/        usb_device/


~$ ls -l /sys/class/pci_bus/0000\:0
0000:00/ 0000:01/


~$ ls -l /sys/class/pci_bus/0000\:0
0000:00/ 0000:01/


~$ ls -l /sys/class/pci_bus/0000\:00/
bridge/      cpuaffinity  uevent


~$ ls -l /sys/class/pci_bus/0000\:00/
total 0
lrwxrwxrwx 1 root root    0 2008-04-16 03:02 bridge -> ../../../devices/pci0000:00
-r--r--r-- 1 root root 4096 2008-04-16 03:02 cpuaffinity
--w------- 1 root root 4096 2008-04-16 03:02 uevent


~$ ls -l /sys/class/pci_bus/0000\:00/bridge
lrwxrwxrwx 1 root root 0 2008-04-16 03:02 /sys/class/pci_bus/0000:00/bridge -> ../../../devices/pci0000:00


~$ ls -l /sys/class/pci_bus/0000\:00/bridge
bridge/


~$ ls -l /sys/class/pci_bus/0000\:00/bridge/
0000:00:00.0/ 0000:00:07.0/ 0000:00:07.2/ 0000:00:0c.0/ 0000:00:10.0/ uevent
0000:00:01.0/ 0000:00:07.1/ 0000:00:07.3/ 0000:00:0e.0/ power/


~$ ls -l /sys/class/pci_bus/0000\:00/bridge/0000\:00\:/
ls: /sys/class/pci_bus/0000:00/bridge/0000:00:/: No such file or directory


~$ ls -l /sys/class/pci_bus/0000\:00/bridge/0000\:00\:10.0/
total 0
lrwxrwxrwx 1 root root     0 2008-04-16 03:03 bus -> ../../../bus/pci
-r--r--r-- 1 root root  4096 2008-04-16 03:03 class
-rw-r--r-- 1 root root   256 2008-04-16 03:03 config
-r--r--r-- 1 root root  4096 2008-04-16 03:03 device
-r--r--r-- 1 root root  4096 2008-04-16 03:03 irq
-r--r--r-- 1 root root  4096 2008-04-16 03:03 local_cpus
-r--r--r-- 1 root root  4096 2008-04-16 03:03 modalias
drwxr-xr-x 2 root root     0 2008-04-03 10:43 power
-r--r--r-- 1 root root  4096 2008-04-16 03:03 resource
-rw------- 1 root root    64 2008-04-16 03:03 resource0
-rw------- 1 root root 65536 2008-04-16 03:03 resource1
-rw------- 1 root root 32768 2008-04-16 03:03 resource2
-r--r--r-- 1 root root  4096 2008-04-16 03:03 subsystem_device
-r--r--r-- 1 root root  4096 2008-04-16 03:03 subsystem_vendor
--w------- 1 root root  4096 2008-04-16 03:03 uevent
-r--r--r-- 1 root root  4096 2008-04-16 03:03 vendor
~$