diff options
author | Linus Torvalds <torvalds@ppc970.osdl.org> | 2005-04-16 18:20:36 -0400 |
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committer | Linus Torvalds <torvalds@ppc970.osdl.org> | 2005-04-16 18:20:36 -0400 |
commit | 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 (patch) | |
tree | 0bba044c4ce775e45a88a51686b5d9f90697ea9d /Documentation/usb/proc_usb_info.txt |
Linux-2.6.12-rc2
Initial git repository build. I'm not bothering with the full history,
even though we have it. We can create a separate "historical" git
archive of that later if we want to, and in the meantime it's about
3.2GB when imported into git - space that would just make the early
git days unnecessarily complicated, when we don't have a lot of good
infrastructure for it.
Let it rip!
Diffstat (limited to 'Documentation/usb/proc_usb_info.txt')
-rw-r--r-- | Documentation/usb/proc_usb_info.txt | 371 |
1 files changed, 371 insertions, 0 deletions
diff --git a/Documentation/usb/proc_usb_info.txt b/Documentation/usb/proc_usb_info.txt new file mode 100644 index 000000000000..729c72d34c89 --- /dev/null +++ b/Documentation/usb/proc_usb_info.txt | |||
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1 | /proc/bus/usb filesystem output | ||
2 | =============================== | ||
3 | (version 2003.05.30) | ||
4 | |||
5 | |||
6 | The usbfs filesystem for USB devices is traditionally mounted at | ||
7 | /proc/bus/usb. It provides the /proc/bus/usb/devices file, as well as | ||
8 | the /proc/bus/usb/BBB/DDD files. | ||
9 | |||
10 | |||
11 | **NOTE**: If /proc/bus/usb appears empty, and a host controller | ||
12 | driver has been linked, then you need to mount the | ||
13 | filesystem. Issue the command (as root): | ||
14 | |||
15 | mount -t usbfs none /proc/bus/usb | ||
16 | |||
17 | An alternative and more permanent method would be to add | ||
18 | |||
19 | none /proc/bus/usb usbfs defaults 0 0 | ||
20 | |||
21 | to /etc/fstab. This will mount usbfs at each reboot. | ||
22 | You can then issue `cat /proc/bus/usb/devices` to extract | ||
23 | USB device information, and user mode drivers can use usbfs | ||
24 | to interact with USB devices. | ||
25 | |||
26 | There are a number of mount options supported by usbfs. | ||
27 | Consult the source code (linux/drivers/usb/core/inode.c) for | ||
28 | information about those options. | ||
29 | |||
30 | **NOTE**: The filesystem has been renamed from "usbdevfs" to | ||
31 | "usbfs", to reduce confusion with "devfs". You may | ||
32 | still see references to the older "usbdevfs" name. | ||
33 | |||
34 | For more information on mounting the usbfs file system, see the | ||
35 | "USB Device Filesystem" section of the USB Guide. The latest copy | ||
36 | of the USB Guide can be found at http://www.linux-usb.org/ | ||
37 | |||
38 | |||
39 | THE /proc/bus/usb/BBB/DDD FILES: | ||
40 | -------------------------------- | ||
41 | Each connected USB device has one file. The BBB indicates the bus | ||
42 | number. The DDD indicates the device address on that bus. Both | ||
43 | of these numbers are assigned sequentially, and can be reused, so | ||
44 | you can't rely on them for stable access to devices. For example, | ||
45 | it's relatively common for devices to re-enumerate while they are | ||
46 | still connected (perhaps someone jostled their power supply, hub, | ||
47 | or USB cable), so a device might be 002/027 when you first connect | ||
48 | it and 002/048 sometime later. | ||
49 | |||
50 | These files can be read as binary data. The binary data consists | ||
51 | of first the device descriptor, then the descriptors for each | ||
52 | configuration of the device. That information is also shown in | ||
53 | text form by the /proc/bus/usb/devices file, described later. | ||
54 | |||
55 | These files may also be used to write user-level drivers for the USB | ||
56 | devices. You would open the /proc/bus/usb/BBB/DDD file read/write, | ||
57 | read its descriptors to make sure it's the device you expect, and then | ||
58 | bind to an interface (or perhaps several) using an ioctl call. You | ||
59 | would issue more ioctls to the device to communicate to it using | ||
60 | control, bulk, or other kinds of USB transfers. The IOCTLs are | ||
61 | listed in the <linux/usbdevice_fs.h> file, and at this writing the | ||
62 | source code (linux/drivers/usb/devio.c) is the primary reference | ||
63 | for how to access devices through those files. | ||
64 | |||
65 | Note that since by default these BBB/DDD files are writable only by | ||
66 | root, only root can write such user mode drivers. You can selectively | ||
67 | grant read/write permissions to other users by using "chmod". Also, | ||
68 | usbfs mount options such as "devmode=0666" may be helpful. | ||
69 | |||
70 | |||
71 | |||
72 | THE /proc/bus/usb/devices FILE: | ||
73 | ------------------------------- | ||
74 | In /proc/bus/usb/devices, each device's output has multiple | ||
75 | lines of ASCII output. | ||
76 | I made it ASCII instead of binary on purpose, so that someone | ||
77 | can obtain some useful data from it without the use of an | ||
78 | auxiliary program. However, with an auxiliary program, the numbers | ||
79 | in the first 4 columns of each "T:" line (topology info: | ||
80 | Lev, Prnt, Port, Cnt) can be used to build a USB topology diagram. | ||
81 | |||
82 | Each line is tagged with a one-character ID for that line: | ||
83 | |||
84 | T = Topology (etc.) | ||
85 | B = Bandwidth (applies only to USB host controllers, which are | ||
86 | virtualized as root hubs) | ||
87 | D = Device descriptor info. | ||
88 | P = Product ID info. (from Device descriptor, but they won't fit | ||
89 | together on one line) | ||
90 | S = String descriptors. | ||
91 | C = Configuration descriptor info. (* = active configuration) | ||
92 | I = Interface descriptor info. | ||
93 | E = Endpoint descriptor info. | ||
94 | |||
95 | ======================================================================= | ||
96 | |||
97 | /proc/bus/usb/devices output format: | ||
98 | |||
99 | Legend: | ||
100 | d = decimal number (may have leading spaces or 0's) | ||
101 | x = hexadecimal number (may have leading spaces or 0's) | ||
102 | s = string | ||
103 | |||
104 | |||
105 | Topology info: | ||
106 | |||
107 | T: Bus=dd Lev=dd Prnt=dd Port=dd Cnt=dd Dev#=ddd Spd=ddd MxCh=dd | ||
108 | | | | | | | | | |__MaxChildren | ||
109 | | | | | | | | |__Device Speed in Mbps | ||
110 | | | | | | | |__DeviceNumber | ||
111 | | | | | | |__Count of devices at this level | ||
112 | | | | | |__Connector/Port on Parent for this device | ||
113 | | | | |__Parent DeviceNumber | ||
114 | | | |__Level in topology for this bus | ||
115 | | |__Bus number | ||
116 | |__Topology info tag | ||
117 | |||
118 | Speed may be: | ||
119 | 1.5 Mbit/s for low speed USB | ||
120 | 12 Mbit/s for full speed USB | ||
121 | 480 Mbit/s for high speed USB (added for USB 2.0) | ||
122 | |||
123 | |||
124 | Bandwidth info: | ||
125 | B: Alloc=ddd/ddd us (xx%), #Int=ddd, #Iso=ddd | ||
126 | | | | |__Number of isochronous requests | ||
127 | | | |__Number of interrupt requests | ||
128 | | |__Total Bandwidth allocated to this bus | ||
129 | |__Bandwidth info tag | ||
130 | |||
131 | Bandwidth allocation is an approximation of how much of one frame | ||
132 | (millisecond) is in use. It reflects only periodic transfers, which | ||
133 | are the only transfers that reserve bandwidth. Control and bulk | ||
134 | transfers use all other bandwidth, including reserved bandwidth that | ||
135 | is not used for transfers (such as for short packets). | ||
136 | |||
137 | The percentage is how much of the "reserved" bandwidth is scheduled by | ||
138 | those transfers. For a low or full speed bus (loosely, "USB 1.1"), | ||
139 | 90% of the bus bandwidth is reserved. For a high speed bus (loosely, | ||
140 | "USB 2.0") 80% is reserved. | ||
141 | |||
142 | |||
143 | Device descriptor info & Product ID info: | ||
144 | |||
145 | D: Ver=x.xx Cls=xx(s) Sub=xx Prot=xx MxPS=dd #Cfgs=dd | ||
146 | P: Vendor=xxxx ProdID=xxxx Rev=xx.xx | ||
147 | |||
148 | where | ||
149 | D: Ver=x.xx Cls=xx(sssss) Sub=xx Prot=xx MxPS=dd #Cfgs=dd | ||
150 | | | | | | | |__NumberConfigurations | ||
151 | | | | | | |__MaxPacketSize of Default Endpoint | ||
152 | | | | | |__DeviceProtocol | ||
153 | | | | |__DeviceSubClass | ||
154 | | | |__DeviceClass | ||
155 | | |__Device USB version | ||
156 | |__Device info tag #1 | ||
157 | |||
158 | where | ||
159 | P: Vendor=xxxx ProdID=xxxx Rev=xx.xx | ||
160 | | | | |__Product revision number | ||
161 | | | |__Product ID code | ||
162 | | |__Vendor ID code | ||
163 | |__Device info tag #2 | ||
164 | |||
165 | |||
166 | String descriptor info: | ||
167 | |||
168 | S: Manufacturer=ssss | ||
169 | | |__Manufacturer of this device as read from the device. | ||
170 | | For USB host controller drivers (virtual root hubs) this may | ||
171 | | be omitted, or (for newer drivers) will identify the kernel | ||
172 | | version and the driver which provides this hub emulation. | ||
173 | |__String info tag | ||
174 | |||
175 | S: Product=ssss | ||
176 | | |__Product description of this device as read from the device. | ||
177 | | For older USB host controller drivers (virtual root hubs) this | ||
178 | | indicates the driver; for newer ones, it's a product (and vendor) | ||
179 | | description that often comes from the kernel's PCI ID database. | ||
180 | |__String info tag | ||
181 | |||
182 | S: SerialNumber=ssss | ||
183 | | |__Serial Number of this device as read from the device. | ||
184 | | For USB host controller drivers (virtual root hubs) this is | ||
185 | | some unique ID, normally a bus ID (address or slot name) that | ||
186 | | can't be shared with any other device. | ||
187 | |__String info tag | ||
188 | |||
189 | |||
190 | |||
191 | Configuration descriptor info: | ||
192 | |||
193 | C:* #Ifs=dd Cfg#=dd Atr=xx MPwr=dddmA | ||
194 | | | | | | |__MaxPower in mA | ||
195 | | | | | |__Attributes | ||
196 | | | | |__ConfiguratioNumber | ||
197 | | | |__NumberOfInterfaces | ||
198 | | |__ "*" indicates the active configuration (others are " ") | ||
199 | |__Config info tag | ||
200 | |||
201 | USB devices may have multiple configurations, each of which act | ||
202 | rather differently. For example, a bus-powered configuration | ||
203 | might be much less capable than one that is self-powered. Only | ||
204 | one device configuration can be active at a time; most devices | ||
205 | have only one configuration. | ||
206 | |||
207 | Each configuration consists of one or more interfaces. Each | ||
208 | interface serves a distinct "function", which is typically bound | ||
209 | to a different USB device driver. One common example is a USB | ||
210 | speaker with an audio interface for playback, and a HID interface | ||
211 | for use with software volume control. | ||
212 | |||
213 | |||
214 | Interface descriptor info (can be multiple per Config): | ||
215 | |||
216 | I: If#=dd Alt=dd #EPs=dd Cls=xx(sssss) Sub=xx Prot=xx Driver=ssss | ||
217 | | | | | | | | |__Driver name | ||
218 | | | | | | | | or "(none)" | ||
219 | | | | | | | |__InterfaceProtocol | ||
220 | | | | | | |__InterfaceSubClass | ||
221 | | | | | |__InterfaceClass | ||
222 | | | | |__NumberOfEndpoints | ||
223 | | | |__AlternateSettingNumber | ||
224 | | |__InterfaceNumber | ||
225 | |__Interface info tag | ||
226 | |||
227 | A given interface may have one or more "alternate" settings. | ||
228 | For example, default settings may not use more than a small | ||
229 | amount of periodic bandwidth. To use significant fractions | ||
230 | of bus bandwidth, drivers must select a non-default altsetting. | ||
231 | |||
232 | Only one setting for an interface may be active at a time, and | ||
233 | only one driver may bind to an interface at a time. Most devices | ||
234 | have only one alternate setting per interface. | ||
235 | |||
236 | |||
237 | Endpoint descriptor info (can be multiple per Interface): | ||
238 | |||
239 | E: Ad=xx(s) Atr=xx(ssss) MxPS=dddd Ivl=dddss | ||
240 | | | | | |__Interval (max) between transfers | ||
241 | | | | |__EndpointMaxPacketSize | ||
242 | | | |__Attributes(EndpointType) | ||
243 | | |__EndpointAddress(I=In,O=Out) | ||
244 | |__Endpoint info tag | ||
245 | |||
246 | The interval is nonzero for all periodic (interrupt or isochronous) | ||
247 | endpoints. For high speed endpoints the transfer interval may be | ||
248 | measured in microseconds rather than milliseconds. | ||
249 | |||
250 | For high speed periodic endpoints, the "MaxPacketSize" reflects | ||
251 | the per-microframe data transfer size. For "high bandwidth" | ||
252 | endpoints, that can reflect two or three packets (for up to | ||
253 | 3KBytes every 125 usec) per endpoint. | ||
254 | |||
255 | With the Linux-USB stack, periodic bandwidth reservations use the | ||
256 | transfer intervals and sizes provided by URBs, which can be less | ||
257 | than those found in endpoint descriptor. | ||
258 | |||
259 | |||
260 | ======================================================================= | ||
261 | |||
262 | |||
263 | If a user or script is interested only in Topology info, for | ||
264 | example, use something like "grep ^T: /proc/bus/usb/devices" | ||
265 | for only the Topology lines. A command like | ||
266 | "grep -i ^[tdp]: /proc/bus/usb/devices" can be used to list | ||
267 | only the lines that begin with the characters in square brackets, | ||
268 | where the valid characters are TDPCIE. With a slightly more able | ||
269 | script, it can display any selected lines (for example, only T, D, | ||
270 | and P lines) and change their output format. (The "procusb" | ||
271 | Perl script is the beginning of this idea. It will list only | ||
272 | selected lines [selected from TBDPSCIE] or "All" lines from | ||
273 | /proc/bus/usb/devices.) | ||
274 | |||
275 | The Topology lines can be used to generate a graphic/pictorial | ||
276 | of the USB devices on a system's root hub. (See more below | ||
277 | on how to do this.) | ||
278 | |||
279 | The Interface lines can be used to determine what driver is | ||
280 | being used for each device. | ||
281 | |||
282 | The Configuration lines could be used to list maximum power | ||
283 | (in milliamps) that a system's USB devices are using. | ||
284 | For example, "grep ^C: /proc/bus/usb/devices". | ||
285 | |||
286 | |||
287 | Here's an example, from a system which has a UHCI root hub, | ||
288 | an external hub connected to the root hub, and a mouse and | ||
289 | a serial converter connected to the external hub. | ||
290 | |||
291 | T: Bus=00 Lev=00 Prnt=00 Port=00 Cnt=00 Dev#= 1 Spd=12 MxCh= 2 | ||
292 | B: Alloc= 28/900 us ( 3%), #Int= 2, #Iso= 0 | ||
293 | D: Ver= 1.00 Cls=09(hub ) Sub=00 Prot=00 MxPS= 8 #Cfgs= 1 | ||
294 | P: Vendor=0000 ProdID=0000 Rev= 0.00 | ||
295 | S: Product=USB UHCI Root Hub | ||
296 | S: SerialNumber=dce0 | ||
297 | C:* #Ifs= 1 Cfg#= 1 Atr=40 MxPwr= 0mA | ||
298 | I: If#= 0 Alt= 0 #EPs= 1 Cls=09(hub ) Sub=00 Prot=00 Driver=hub | ||
299 | E: Ad=81(I) Atr=03(Int.) MxPS= 8 Ivl=255ms | ||
300 | T: Bus=00 Lev=01 Prnt=01 Port=00 Cnt=01 Dev#= 2 Spd=12 MxCh= 4 | ||
301 | D: Ver= 1.00 Cls=09(hub ) Sub=00 Prot=00 MxPS= 8 #Cfgs= 1 | ||
302 | P: Vendor=0451 ProdID=1446 Rev= 1.00 | ||
303 | C:* #Ifs= 1 Cfg#= 1 Atr=e0 MxPwr=100mA | ||
304 | I: If#= 0 Alt= 0 #EPs= 1 Cls=09(hub ) Sub=00 Prot=00 Driver=hub | ||
305 | E: Ad=81(I) Atr=03(Int.) MxPS= 1 Ivl=255ms | ||
306 | T: Bus=00 Lev=02 Prnt=02 Port=00 Cnt=01 Dev#= 3 Spd=1.5 MxCh= 0 | ||
307 | D: Ver= 1.00 Cls=00(>ifc ) Sub=00 Prot=00 MxPS= 8 #Cfgs= 1 | ||
308 | P: Vendor=04b4 ProdID=0001 Rev= 0.00 | ||
309 | C:* #Ifs= 1 Cfg#= 1 Atr=80 MxPwr=100mA | ||
310 | I: If#= 0 Alt= 0 #EPs= 1 Cls=03(HID ) Sub=01 Prot=02 Driver=mouse | ||
311 | E: Ad=81(I) Atr=03(Int.) MxPS= 3 Ivl= 10ms | ||
312 | T: Bus=00 Lev=02 Prnt=02 Port=02 Cnt=02 Dev#= 4 Spd=12 MxCh= 0 | ||
313 | D: Ver= 1.00 Cls=00(>ifc ) Sub=00 Prot=00 MxPS= 8 #Cfgs= 1 | ||
314 | P: Vendor=0565 ProdID=0001 Rev= 1.08 | ||
315 | S: Manufacturer=Peracom Networks, Inc. | ||
316 | S: Product=Peracom USB to Serial Converter | ||
317 | C:* #Ifs= 1 Cfg#= 1 Atr=a0 MxPwr=100mA | ||
318 | I: If#= 0 Alt= 0 #EPs= 3 Cls=00(>ifc ) Sub=00 Prot=00 Driver=serial | ||
319 | E: Ad=81(I) Atr=02(Bulk) MxPS= 64 Ivl= 16ms | ||
320 | E: Ad=01(O) Atr=02(Bulk) MxPS= 16 Ivl= 16ms | ||
321 | E: Ad=82(I) Atr=03(Int.) MxPS= 8 Ivl= 8ms | ||
322 | |||
323 | |||
324 | Selecting only the "T:" and "I:" lines from this (for example, by using | ||
325 | "procusb ti"), we have: | ||
326 | |||
327 | T: Bus=00 Lev=00 Prnt=00 Port=00 Cnt=00 Dev#= 1 Spd=12 MxCh= 2 | ||
328 | T: Bus=00 Lev=01 Prnt=01 Port=00 Cnt=01 Dev#= 2 Spd=12 MxCh= 4 | ||
329 | I: If#= 0 Alt= 0 #EPs= 1 Cls=09(hub ) Sub=00 Prot=00 Driver=hub | ||
330 | T: Bus=00 Lev=02 Prnt=02 Port=00 Cnt=01 Dev#= 3 Spd=1.5 MxCh= 0 | ||
331 | I: If#= 0 Alt= 0 #EPs= 1 Cls=03(HID ) Sub=01 Prot=02 Driver=mouse | ||
332 | T: Bus=00 Lev=02 Prnt=02 Port=02 Cnt=02 Dev#= 4 Spd=12 MxCh= 0 | ||
333 | I: If#= 0 Alt= 0 #EPs= 3 Cls=00(>ifc ) Sub=00 Prot=00 Driver=serial | ||
334 | |||
335 | |||
336 | Physically this looks like (or could be converted to): | ||
337 | |||
338 | +------------------+ | ||
339 | | PC/root_hub (12)| Dev# = 1 | ||
340 | +------------------+ (nn) is Mbps. | ||
341 | Level 0 | CN.0 | CN.1 | [CN = connector/port #] | ||
342 | +------------------+ | ||
343 | / | ||
344 | / | ||
345 | +-----------------------+ | ||
346 | Level 1 | Dev#2: 4-port hub (12)| | ||
347 | +-----------------------+ | ||
348 | |CN.0 |CN.1 |CN.2 |CN.3 | | ||
349 | +-----------------------+ | ||
350 | \ \____________________ | ||
351 | \_____ \ | ||
352 | \ \ | ||
353 | +--------------------+ +--------------------+ | ||
354 | Level 2 | Dev# 3: mouse (1.5)| | Dev# 4: serial (12)| | ||
355 | +--------------------+ +--------------------+ | ||
356 | |||
357 | |||
358 | |||
359 | Or, in a more tree-like structure (ports [Connectors] without | ||
360 | connections could be omitted): | ||
361 | |||
362 | PC: Dev# 1, root hub, 2 ports, 12 Mbps | ||
363 | |_ CN.0: Dev# 2, hub, 4 ports, 12 Mbps | ||
364 | |_ CN.0: Dev #3, mouse, 1.5 Mbps | ||
365 | |_ CN.1: | ||
366 | |_ CN.2: Dev #4, serial, 12 Mbps | ||
367 | |_ CN.3: | ||
368 | |_ CN.1: | ||
369 | |||
370 | |||
371 | ### END ### | ||