to /etc/fstab. This will mount usbfs at each reboot.
You can then issue `cat /proc/bus/usb/devices` to extract
- USB device information, and user mode drivers can use usbfs
+ USB device information, and user mode drivers can use usbfs
to interact with USB devices.
There are a number of mount options supported by usbfs.
still see references to the older "usbdevfs" name.
For more information on mounting the usbfs file system, see the
-"USB Device Filesystem" section of the USB Guide. The latest copy
+"USB Device Filesystem" section of the USB Guide. The latest copy
of the USB Guide can be found at http://www.linux-usb.org/
These files can be read as binary data. The binary data consists
of first the device descriptor, then the descriptors for each
-configuration of the device. That information is also shown in
-text form by the /proc/bus/usb/devices file, described later.
+configuration of the device. Multi-byte fields in the device and
+configuration descriptors, but not other descriptors, are converted
+to host endianness by the kernel. This information is also shown
+in text form by the /proc/bus/usb/devices file, described later.
These files may also be used to write user-level drivers for the USB
devices. You would open the /proc/bus/usb/BBB/DDD file read/write,
would issue more ioctls to the device to communicate to it using
control, bulk, or other kinds of USB transfers. The IOCTLs are
listed in the <linux/usbdevice_fs.h> file, and at this writing the
-source code (linux/drivers/usb/devio.c) is the primary reference
+source code (linux/drivers/usb/core/devio.c) is the primary reference
for how to access devices through those files.
Note that since by default these BBB/DDD files are writable only by
are the only transfers that reserve bandwidth. Control and bulk
transfers use all other bandwidth, including reserved bandwidth that
is not used for transfers (such as for short packets).
-
+
The percentage is how much of the "reserved" bandwidth is scheduled by
those transfers. For a low or full speed bus (loosely, "USB 1.1"),
90% of the bus bandwidth is reserved. For a high speed bus (loosely,
| | |__NumberOfInterfaces
| |__ "*" indicates the active configuration (others are " ")
|__Config info tag
-
+
USB devices may have multiple configurations, each of which act
rather differently. For example, a bus-powered configuration
might be much less capable than one that is self-powered. Only
Interface descriptor info (can be multiple per Config):
-I: If#=dd Alt=dd #EPs=dd Cls=xx(sssss) Sub=xx Prot=xx Driver=ssss
-| | | | | | | |__Driver name
-| | | | | | | or "(none)"
-| | | | | | |__InterfaceProtocol
-| | | | | |__InterfaceSubClass
-| | | | |__InterfaceClass
-| | | |__NumberOfEndpoints
-| | |__AlternateSettingNumber
-| |__InterfaceNumber
+I:* If#=dd Alt=dd #EPs=dd Cls=xx(sssss) Sub=xx Prot=xx Driver=ssss
+| | | | | | | | |__Driver name
+| | | | | | | | or "(none)"
+| | | | | | | |__InterfaceProtocol
+| | | | | | |__InterfaceSubClass
+| | | | | |__InterfaceClass
+| | | | |__NumberOfEndpoints
+| | | |__AlternateSettingNumber
+| | |__InterfaceNumber
+| |__ "*" indicates the active altsetting (others are " ")
|__Interface info tag
A given interface may have one or more "alternate" settings.
For example, default settings may not use more than a small
amount of periodic bandwidth. To use significant fractions
of bus bandwidth, drivers must select a non-default altsetting.
-
+
Only one setting for an interface may be active at a time, and
only one driver may bind to an interface at a time. Most devices
have only one alternate setting per interface.
on how to do this.)
The Interface lines can be used to determine what driver is
-being used for each device.
+being used for each device, and which altsetting it activated.
The Configuration lines could be used to list maximum power
(in milliamps) that a system's USB devices are using.
C:* #Ifs= 1 Cfg#= 1 Atr=40 MxPwr= 0mA
I: If#= 0 Alt= 0 #EPs= 1 Cls=09(hub ) Sub=00 Prot=00 Driver=hub
E: Ad=81(I) Atr=03(Int.) MxPS= 8 Ivl=255ms
+
T: Bus=00 Lev=01 Prnt=01 Port=00 Cnt=01 Dev#= 2 Spd=12 MxCh= 4
D: Ver= 1.00 Cls=09(hub ) Sub=00 Prot=00 MxPS= 8 #Cfgs= 1
P: Vendor=0451 ProdID=1446 Rev= 1.00
C:* #Ifs= 1 Cfg#= 1 Atr=e0 MxPwr=100mA
I: If#= 0 Alt= 0 #EPs= 1 Cls=09(hub ) Sub=00 Prot=00 Driver=hub
E: Ad=81(I) Atr=03(Int.) MxPS= 1 Ivl=255ms
+
T: Bus=00 Lev=02 Prnt=02 Port=00 Cnt=01 Dev#= 3 Spd=1.5 MxCh= 0
D: Ver= 1.00 Cls=00(>ifc ) Sub=00 Prot=00 MxPS= 8 #Cfgs= 1
P: Vendor=04b4 ProdID=0001 Rev= 0.00
C:* #Ifs= 1 Cfg#= 1 Atr=80 MxPwr=100mA
I: If#= 0 Alt= 0 #EPs= 1 Cls=03(HID ) Sub=01 Prot=02 Driver=mouse
E: Ad=81(I) Atr=03(Int.) MxPS= 3 Ivl= 10ms
+
T: Bus=00 Lev=02 Prnt=02 Port=02 Cnt=02 Dev#= 4 Spd=12 MxCh= 0
D: Ver= 1.00 Cls=00(>ifc ) Sub=00 Prot=00 MxPS= 8 #Cfgs= 1
P: Vendor=0565 ProdID=0001 Rev= 1.08
git://ftp.safe.ca / safe / jmp / linux-2.6 / blobdiff