usb topology分析

在linux doc的proc_usb_info.txt 中：

/proc/bus/usb/devices 中T = Topology (etc.)开头的行可以分析拓扑

Topology info:

T:  Bus=dd Lev=dd Prnt=dd Port=dd Cnt=dd Dev#=ddd Spd=ddd MxCh=dd
|   |      |      |       |       |      |        |       |__MaxChildren
|   |      |      |       |       |      |        |__Device Speed in Mbps
|   |      |      |       |       |      |__DeviceNumber
|   |      |      |       |       |__Count of devices at this level
|   |      |      |       |__Connector/Port on Parent for this device
|   |      |      |__Parent DeviceNumber
|   |      |__Level in topology for this bus
|   |__Bus number
|__Topology info tag

    Speed may be:
        1.5    Mbit/s for low speed USB
    12    Mbit/s for full speed USB
    480    Mbit/s for high speed USB (added for USB 2.0)

 

例子：

T:  Bus=00 Lev=00 Prnt=00 Port=00 Cnt=00 Dev#=  1 Spd=12  MxCh= 2
T:  Bus=00 Lev=01 Prnt=01 Port=00 Cnt=01 Dev#=  2 Spd=12  MxCh= 4
I:  If#= 0 Alt= 0 #EPs= 1 Cls=09(hub  ) Sub=00 Prot=00 Driver=hub
T:  Bus=00 Lev=02 Prnt=02 Port=00 Cnt=01 Dev#=  3 Spd=1.5 MxCh= 0
I:  If#= 0 Alt= 0 #EPs= 1 Cls=03(HID  ) Sub=01 Prot=02 Driver=mouse
T:  Bus=00 Lev=02 Prnt=02 Port=02 Cnt=02 Dev#=  4 Spd=12  MxCh= 0
I:  If#= 0 Alt= 0 #EPs= 3 Cls=00(>ifc ) Sub=00 Prot=00 Driver=serial

Physically this looks like (or could be converted to):

                      +------------------+
                      |  PC/root_hub (12)|   Dev# = 1
                      +------------------+   (nn) is Mbps.
    Level 0           |  CN.0   |  CN.1  |   [CN = connector/port #]
                      +------------------+
                          /
                         /
            +-----------------------+
  Level 1   | Dev#2: 4-port hub (12)|
            +-----------------------+
            |CN.0 |CN.1 |CN.2 |CN.3 |
            +-----------------------+
                \           \____________________
                 \_____                          \
                       \                          \
               +--------------------+      +--------------------+
  Level 2      | Dev# 3: mouse (1.5)|      | Dev# 4: serial (12)|
               +--------------------+      +--------------------+

Or, in a more tree-like structure (ports [Connectors] without
connections could be omitted):

PC:  Dev# 1, root hub, 2 ports, 12 Mbps
|_ CN.0:  Dev# 2, hub, 4 ports, 12 Mbps
     |_ CN.0:  Dev #3, mouse, 1.5 Mbps
     |_ CN.1:
     |_ CN.2:  Dev #4, serial, 12 Mbps
     |_ CN.3:
|_ CN.1:

                         ### END ###