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Diffstat (limited to 'Documentation/usb/proc_usb_info.txt')
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diff --git a/Documentation/usb/proc_usb_info.txt b/Documentation/usb/proc_usb_info.txt deleted file mode 100644 index 98be91982677..000000000000 --- a/Documentation/usb/proc_usb_info.txt +++ /dev/null @@ -1,390 +0,0 @@ -/proc/bus/usb filesystem output -=============================== -(version 2010.09.13) - - -The usbfs filesystem for USB devices is traditionally mounted at -/proc/bus/usb. It provides the /proc/bus/usb/devices file, as well as -the /proc/bus/usb/BBB/DDD files. - -In many modern systems the usbfs filesystem isn't used at all. Instead -USB device nodes are created under /dev/usb/ or someplace similar. The -"devices" file is available in debugfs, typically as -/sys/kernel/debug/usb/devices. - - -**NOTE**: If /proc/bus/usb appears empty, and a host controller - driver has been linked, then you need to mount the - filesystem. Issue the command (as root): - - mount -t usbfs none /proc/bus/usb - - An alternative and more permanent method would be to add - - none /proc/bus/usb usbfs defaults 0 0 - - 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 - to interact with USB devices. - - There are a number of mount options supported by usbfs. - Consult the source code (linux/drivers/usb/core/inode.c) for - information about those options. - -**NOTE**: The filesystem has been renamed from "usbdevfs" to - "usbfs", to reduce confusion with "devfs". You may - 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 -of the USB Guide can be found at http://www.linux-usb.org/ - - -THE /proc/bus/usb/BBB/DDD FILES: --------------------------------- -Each connected USB device has one file. The BBB indicates the bus -number. The DDD indicates the device address on that bus. Both -of these numbers are assigned sequentially, and can be reused, so -you can't rely on them for stable access to devices. For example, -it's relatively common for devices to re-enumerate while they are -still connected (perhaps someone jostled their power supply, hub, -or USB cable), so a device might be 002/027 when you first connect -it and 002/048 sometime later. - -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. Multi-byte fields in the device descriptor -are converted to host endianness by the kernel. The configuration -descriptors are in bus endian format! The configuration descriptor -are wTotalLength bytes apart. If a device returns less configuration -descriptor data than indicated by wTotalLength there will be a hole in -the file for the missing bytes. 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, -read its descriptors to make sure it's the device you expect, and then -bind to an interface (or perhaps several) using an ioctl call. You -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/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 -root, only root can write such user mode drivers. You can selectively -grant read/write permissions to other users by using "chmod". Also, -usbfs mount options such as "devmode=0666" may be helpful. - - - -THE /proc/bus/usb/devices FILE: -------------------------------- -In /proc/bus/usb/devices, each device's output has multiple -lines of ASCII output. -I made it ASCII instead of binary on purpose, so that someone -can obtain some useful data from it without the use of an -auxiliary program. However, with an auxiliary program, the numbers -in the first 4 columns of each "T:" line (topology info: -Lev, Prnt, Port, Cnt) can be used to build a USB topology diagram. - -Each line is tagged with a one-character ID for that line: - -T = Topology (etc.) -B = Bandwidth (applies only to USB host controllers, which are - virtualized as root hubs) -D = Device descriptor info. -P = Product ID info. (from Device descriptor, but they won't fit - together on one line) -S = String descriptors. -C = Configuration descriptor info. (* = active configuration) -I = Interface descriptor info. -E = Endpoint descriptor info. - -======================================================================= - -/proc/bus/usb/devices output format: - -Legend: - d = decimal number (may have leading spaces or 0's) - x = hexadecimal number (may have leading spaces or 0's) - s = string - - -Topology info: - -T: Bus=dd Lev=dd Prnt=dd Port=dd Cnt=dd Dev#=ddd Spd=dddd 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); - also used for Wireless USB, which has no fixed speed - 5000 Mbit/s for SuperSpeed USB (added for USB 3.0) - - For reasons lost in the mists of time, the Port number is always - too low by 1. For example, a device plugged into port 4 will - show up with "Port=03". - -Bandwidth info: -B: Alloc=ddd/ddd us (xx%), #Int=ddd, #Iso=ddd -| | | |__Number of isochronous requests -| | |__Number of interrupt requests -| |__Total Bandwidth allocated to this bus -|__Bandwidth info tag - - Bandwidth allocation is an approximation of how much of one frame - (millisecond) is in use. It reflects only periodic transfers, which - 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, - "USB 2.0") 80% is reserved. - - -Device descriptor info & Product ID info: - -D: Ver=x.xx Cls=xx(s) Sub=xx Prot=xx MxPS=dd #Cfgs=dd -P: Vendor=xxxx ProdID=xxxx Rev=xx.xx - -where -D: Ver=x.xx Cls=xx(sssss) Sub=xx Prot=xx MxPS=dd #Cfgs=dd -| | | | | | |__NumberConfigurations -| | | | | |__MaxPacketSize of Default Endpoint -| | | | |__DeviceProtocol -| | | |__DeviceSubClass -| | |__DeviceClass -| |__Device USB version -|__Device info tag #1 - -where -P: Vendor=xxxx ProdID=xxxx Rev=xx.xx -| | | |__Product revision number -| | |__Product ID code -| |__Vendor ID code -|__Device info tag #2 - - -String descriptor info: - -S: Manufacturer=ssss -| |__Manufacturer of this device as read from the device. -| For USB host controller drivers (virtual root hubs) this may -| be omitted, or (for newer drivers) will identify the kernel -| version and the driver which provides this hub emulation. -|__String info tag - -S: Product=ssss -| |__Product description of this device as read from the device. -| For older USB host controller drivers (virtual root hubs) this -| indicates the driver; for newer ones, it's a product (and vendor) -| description that often comes from the kernel's PCI ID database. -|__String info tag - -S: SerialNumber=ssss -| |__Serial Number of this device as read from the device. -| For USB host controller drivers (virtual root hubs) this is -| some unique ID, normally a bus ID (address or slot name) that -| can't be shared with any other device. -|__String info tag - - - -Configuration descriptor info: - -C:* #Ifs=dd Cfg#=dd Atr=xx MPwr=dddmA -| | | | | |__MaxPower in mA -| | | | |__Attributes -| | | |__ConfiguratioNumber -| | |__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 - one device configuration can be active at a time; most devices - have only one configuration. - - Each configuration consists of one or more interfaces. Each - interface serves a distinct "function", which is typically bound - to a different USB device driver. One common example is a USB - speaker with an audio interface for playback, and a HID interface - for use with software volume control. - - -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 -| |__ "*" 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. - - -Endpoint descriptor info (can be multiple per Interface): - -E: Ad=xx(s) Atr=xx(ssss) MxPS=dddd Ivl=dddss -| | | | |__Interval (max) between transfers -| | | |__EndpointMaxPacketSize -| | |__Attributes(EndpointType) -| |__EndpointAddress(I=In,O=Out) -|__Endpoint info tag - - The interval is nonzero for all periodic (interrupt or isochronous) - endpoints. For high speed endpoints the transfer interval may be - measured in microseconds rather than milliseconds. - - For high speed periodic endpoints, the "MaxPacketSize" reflects - the per-microframe data transfer size. For "high bandwidth" - endpoints, that can reflect two or three packets (for up to - 3KBytes every 125 usec) per endpoint. - - With the Linux-USB stack, periodic bandwidth reservations use the - transfer intervals and sizes provided by URBs, which can be less - than those found in endpoint descriptor. - - -======================================================================= - - -If a user or script is interested only in Topology info, for -example, use something like "grep ^T: /proc/bus/usb/devices" -for only the Topology lines. A command like -"grep -i ^[tdp]: /proc/bus/usb/devices" can be used to list -only the lines that begin with the characters in square brackets, -where the valid characters are TDPCIE. With a slightly more able -script, it can display any selected lines (for example, only T, D, -and P lines) and change their output format. (The "procusb" -Perl script is the beginning of this idea. It will list only -selected lines [selected from TBDPSCIE] or "All" lines from -/proc/bus/usb/devices.) - -The Topology lines can be used to generate a graphic/pictorial -of the USB devices on a system's root hub. (See more below -on how to do this.) - -The Interface lines can be used to determine what driver is -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. -For example, "grep ^C: /proc/bus/usb/devices". - - -Here's an example, from a system which has a UHCI root hub, -an external hub connected to the root hub, and a mouse and -a serial converter connected to the external hub. - -T: Bus=00 Lev=00 Prnt=00 Port=00 Cnt=00 Dev#= 1 Spd=12 MxCh= 2 -B: Alloc= 28/900 us ( 3%), #Int= 2, #Iso= 0 -D: Ver= 1.00 Cls=09(hub ) Sub=00 Prot=00 MxPS= 8 #Cfgs= 1 -P: Vendor=0000 ProdID=0000 Rev= 0.00 -S: Product=USB UHCI Root Hub -S: SerialNumber=dce0 -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 -S: Manufacturer=Peracom Networks, Inc. -S: Product=Peracom USB to Serial Converter -C:* #Ifs= 1 Cfg#= 1 Atr=a0 MxPwr=100mA -I: If#= 0 Alt= 0 #EPs= 3 Cls=00(>ifc ) Sub=00 Prot=00 Driver=serial -E: Ad=81(I) Atr=02(Bulk) MxPS= 64 Ivl= 16ms -E: Ad=01(O) Atr=02(Bulk) MxPS= 16 Ivl= 16ms -E: Ad=82(I) Atr=03(Int.) MxPS= 8 Ivl= 8ms - - -Selecting only the "T:" and "I:" lines from this (for example, by using -"procusb ti"), we have: - -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 ### |