Documentation/usb/usbip_protocol.rst

   1 ===============
   2 USB/IP protocol
   3 ===============
   4
   5 PRELIMINARY DRAFT, MAY CONTAIN MISTAKES!
   6 28 Jun 2011
   7
   8 The USB/IP protocol follows a server/client architecture. The server exports the
   9 USB devices and the clients imports them. The device driver for the exported
  10 USB device runs on the client machine.
  11
  12 The client may ask for the list of the exported USB devices. To get the list the
  13 client opens a TCP/IP connection towards the server, and sends an OP_REQ_DEVLIST
  14 packet on top of the TCP/IP connection (so the actual OP_REQ_DEVLIST may be sent
  15 in one or more pieces at the low level transport layer). The server sends back
  16 the OP_REP_DEVLIST packet which lists the exported USB devices. Finally the
  17 TCP/IP connection is closed.
  18
  19 ::
  20
  21  virtual host controller                                 usb host
  22       "client"                                           "server"
  23   (imports USB devices)                             (exports USB devices)
  24           |                                                 |
  25           |                  OP_REQ_DEVLIST                 |
  26           | ----------------------------------------------> |
  27           |                                                 |
  28           |                  OP_REP_DEVLIST                 |
  29           | <---------------------------------------------- |
  30           |                                                 |
  31
  32 Once the client knows the list of exported USB devices it may decide to use one
  33 of them. First the client opens a TCP/IP connection towards the server and
  34 sends an OP_REQ_IMPORT packet. The server replies with OP_REP_IMPORT. If the
  35 import was successful the TCP/IP connection remains open and will be used
  36 to transfer the URB traffic between the client and the server. The client may
  37 send two types of packets: the USBIP_CMD_SUBMIT to submit an URB, and
  38 USBIP_CMD_UNLINK to unlink a previously submitted URB. The answers of the
  39 server may be USBIP_RET_SUBMIT and USBIP_RET_UNLINK respectively.
  40
  41 ::
  42
  43  virtual host controller                                 usb host
  44       "client"                                           "server"
  45   (imports USB devices)                             (exports USB devices)
  46           |                                                 |
  47           |                  OP_REQ_IMPORT                  |
  48           | ----------------------------------------------> |
  49           |                                                 |
  50           |                  OP_REP_IMPORT                  |
  51           | <---------------------------------------------- |
  52           |                                                 |
  53           |                                                 |
  54           |            USBIP_CMD_SUBMIT(seqnum = n)         |
  55           | ----------------------------------------------> |
  56           |                                                 |
  57           |            USBIP_RET_SUBMIT(seqnum = n)         |
  58           | <---------------------------------------------- |
  59           |                        .                        |
  60           |                        :                        |
  61           |                                                 |
  62           |            USBIP_CMD_SUBMIT(seqnum = m)         |
  63           | ----------------------------------------------> |
  64           |                                                 |
  65           |            USBIP_CMD_SUBMIT(seqnum = m+1)       |
  66           | ----------------------------------------------> |
  67           |                                                 |
  68           |            USBIP_CMD_SUBMIT(seqnum = m+2)       |
  69           | ----------------------------------------------> |
  70           |                                                 |
  71           |            USBIP_RET_SUBMIT(seqnum = m)         |
  72           | <---------------------------------------------- |
  73           |                                                 |
  74           |            USBIP_CMD_SUBMIT(seqnum = m+3)       |
  75           | ----------------------------------------------> |
  76           |                                                 |
  77           |            USBIP_RET_SUBMIT(seqnum = m+1)       |
  78           | <---------------------------------------------- |
  79           |                                                 |
  80           |            USBIP_CMD_SUBMIT(seqnum = m+4)       |
  81           | ----------------------------------------------> |
  82           |                                                 |
  83           |            USBIP_RET_SUBMIT(seqnum = m+2)       |
  84           | <---------------------------------------------- |
  85           |                        .                        |
  86           |                        :                        |
  87           |                                                 |
  88           |               USBIP_CMD_UNLINK                  |
  89           | ----------------------------------------------> |
  90           |                                                 |
  91           |               USBIP_RET_UNLINK                  |
  92           | <---------------------------------------------- |
  93           |                                                 |
  94
  95 The fields are in network (big endian) byte order meaning that the most significant
  96 byte (MSB) is stored at the lowest address.
  97
  98
  99 OP_REQ_DEVLIST:
 100         Retrieve the list of exported USB devices.
 101
 102 +-----------+--------+------------+---------------------------------------------------+
 103 | Offset    | Length | Value      | Description                                       |
 104 +===========+========+============+===================================================+
 105 | 0         | 2      | 0x0100     | Binary-coded decimal USBIP version number: v1.0.0 |
 106 +-----------+--------+------------+---------------------------------------------------+
 107 | 2         | 2      | 0x8005     | Command code: Retrieve the list of exported USB   |
 108 |           |        |            | devices.                                          |
 109 +-----------+--------+------------+---------------------------------------------------+
 110 | 4         | 4      | 0x00000000 | Status: unused, shall be set to 0                 |
 111 +-----------+--------+------------+---------------------------------------------------+
 112
 113 OP_REP_DEVLIST:
 114         Reply with the list of exported USB devices.
 115
 116 +-----------+--------+------------+---------------------------------------------------+
 117 | Offset    | Length | Value      | Description                                       |
 118 +===========+========+============+===================================================+
 119 | 0         | 2      | 0x0100     | Binary-coded decimal USBIP version number: v1.0.0.|
 120 +-----------+--------+------------+---------------------------------------------------+
 121 | 2         | 2      | 0x0005     | Reply code: The list of exported USB devices.     |
 122 +-----------+--------+------------+---------------------------------------------------+
 123 | 4         | 4      | 0x00000000 | Status: 0 for OK                                  |
 124 +-----------+--------+------------+---------------------------------------------------+
 125 | 8         | 4      | n          | Number of exported devices: 0 means no exported   |
 126 |           |        |            | devices.                                          |
 127 +-----------+--------+------------+---------------------------------------------------+
 128 | 0x0C      |        |            | From now on the exported n devices are described, |
 129 |           |        |            | if any. If no devices are exported the message    |
 130 |           |        |            | ends with the previous "number of exported        |
 131 |           |        |            | devices" field.                                   |
 132 +-----------+--------+------------+---------------------------------------------------+
 133 |           | 256    |            | path: Path of the device on the host exporting the|
 134 |           |        |            | USB device, string closed with zero byte, e.g.    |
 135 |           |        |            | "/sys/devices/pci0000:00/0000:00:1d.1/usb3/3-2"   |
 136 |           |        |            | The unused bytes shall be filled with zero        |
 137 |           |        |            | bytes.                                            |
 138 +-----------+--------+------------+---------------------------------------------------+
 139 | 0x10C     | 32     |            | busid: Bus ID of the exported device, string      |
 140 |           |        |            | closed with zero byte, e.g. "3-2". The unused     |
 141 |           |        |            | bytes shall be filled with zero bytes.            |
 142 +-----------+--------+------------+---------------------------------------------------+
 143 | 0x12C     | 4      |            | busnum                                            |
 144 +-----------+--------+------------+---------------------------------------------------+
 145 | 0x130     | 4      |            | devnum                                            |
 146 +-----------+--------+------------+---------------------------------------------------+
 147 | 0x134     | 4      |            | speed                                             |
 148 +-----------+--------+------------+---------------------------------------------------+
 149 | 0x138     | 2      |            | idVendor                                          |
 150 +-----------+--------+------------+---------------------------------------------------+
 151 | 0x13A     | 2      |            | idProduct                                         |
 152 +-----------+--------+------------+---------------------------------------------------+
 153 | 0x13C     | 2      |            | bcdDevice                                         |
 154 +-----------+--------+------------+---------------------------------------------------+
 155 | 0x13E     | 1      |            | bDeviceClass                                      |
 156 +-----------+--------+------------+---------------------------------------------------+
 157 | 0x13F     | 1      |            | bDeviceSubClass                                   |
 158 +-----------+--------+------------+---------------------------------------------------+
 159 | 0x140     | 1      |            | bDeviceProtocol                                   |
 160 +-----------+--------+------------+---------------------------------------------------+
 161 | 0x141     | 1      |            | bConfigurationValue                               |
 162 +-----------+--------+------------+---------------------------------------------------+
 163 | 0x142     | 1      |            | bNumConfigurations                                |
 164 +-----------+--------+------------+---------------------------------------------------+
 165 | 0x143     | 1      |            | bNumInterfaces                                    |
 166 +-----------+--------+------------+---------------------------------------------------+
 167 | 0x144     |        | m_0        | From now on each interface is described, all      |
 168 |           |        |            | together bNumInterfaces times, with the           |
 169 |           |        |            | the following 4 fields:                           |
 170 +-----------+--------+------------+---------------------------------------------------+
 171 |           | 1      |            | bInterfaceClass                                   |
 172 +-----------+--------+------------+---------------------------------------------------+
 173 | 0x145     | 1      |            | bInterfaceSubClass                                |
 174 +-----------+--------+------------+---------------------------------------------------+
 175 | 0x146     | 1      |            | bInterfaceProtocol                                |
 176 +-----------+--------+------------+---------------------------------------------------+
 177 | 0x147     | 1      |            | padding byte for alignment, shall be set to zero  |
 178 +-----------+--------+------------+---------------------------------------------------+
 179 | 0xC +     |        |            | The second exported USB device starts at i=1      |
 180 | i*0x138 + |        |            | with the busid field.                             |
 181 | m_(i-1)*4 |        |            |                                                   |
 182 +-----------+--------+------------+---------------------------------------------------+
 183
 184 OP_REQ_IMPORT:
 185         Request to import (attach) a remote USB device.
 186
 187 +-----------+--------+------------+---------------------------------------------------+
 188 | Offset    | Length | Value      | Description                                       |
 189 +===========+========+============+===================================================+
 190 | 0         | 2      | 0x0100     | Binary-coded decimal USBIP version number: v1.0.0 |
 191 +-----------+--------+------------+---------------------------------------------------+
 192 | 2         | 2      | 0x8003     | Command code: import a remote USB device.         |
 193 +-----------+--------+------------+---------------------------------------------------+
 194 | 4         | 4      | 0x00000000 | Status: unused, shall be set to 0                 |
 195 +-----------+--------+------------+---------------------------------------------------+
 196 | 8         | 32     |            | busid: the busid of the exported device on the    |
 197 |           |        |            | remote host. The possible values are taken        |
 198 |           |        |            | from the message field OP_REP_DEVLIST.busid.      |
 199 |           |        |            | A string closed with zero, the unused bytes       |
 200 |           |        |            | shall be filled with zeros.                       |
 201 +-----------+--------+------------+---------------------------------------------------+
 202
 203 OP_REP_IMPORT:
 204         Reply to import (attach) a remote USB device.
 205
 206 +-----------+--------+------------+---------------------------------------------------+
 207 | Offset    | Length | Value      | Description                                       |
 208 +===========+========+============+===================================================+
 209 | 0         | 2      | 0x0100     | Binary-coded decimal USBIP version number: v1.0.0 |
 210 +-----------+--------+------------+---------------------------------------------------+
 211 | 2         | 2      | 0x0003     | Reply code: Reply to import.                      |
 212 +-----------+--------+------------+---------------------------------------------------+
 213 | 4         | 4      | 0x00000000 | Status:                                           |
 214 |           |        |            |                                                   |
 215 |           |        |            |   - 0 for OK                                      |
 216 |           |        |            |   - 1 for error                                   |
 217 +-----------+--------+------------+---------------------------------------------------+
 218 | 8         |        |            | From now on comes the details of the imported     |
 219 |           |        |            | device, if the previous status field was OK (0),  |
 220 |           |        |            | otherwise the reply ends with the status field.   |
 221 +-----------+--------+------------+---------------------------------------------------+
 222 |           | 256    |            | path: Path of the device on the host exporting the|
 223 |           |        |            | USB device, string closed with zero byte, e.g.    |
 224 |           |        |            | "/sys/devices/pci0000:00/0000:00:1d.1/usb3/3-2"   |
 225 |           |        |            | The unused bytes shall be filled with zero        |
 226 |           |        |            | bytes.                                            |
 227 +-----------+--------+------------+---------------------------------------------------+
 228 | 0x108     | 32     |            | busid: Bus ID of the exported device, string      |
 229 |           |        |            | closed with zero byte, e.g. "3-2". The unused     |
 230 |           |        |            | bytes shall be filled with zero bytes.            |
 231 +-----------+--------+------------+---------------------------------------------------+
 232 | 0x128     | 4      |            | busnum                                            |
 233 +-----------+--------+------------+---------------------------------------------------+
 234 | 0x12C     | 4      |            | devnum                                            |
 235 +-----------+--------+------------+---------------------------------------------------+
 236 | 0x130     | 4      |            | speed                                             |
 237 +-----------+--------+------------+---------------------------------------------------+
 238 | 0x134     | 2      |            | idVendor                                          |
 239 +-----------+--------+------------+---------------------------------------------------+
 240 | 0x136     | 2      |            | idProduct                                         |
 241 +-----------+--------+------------+---------------------------------------------------+
 242 | 0x138     | 2      |            | bcdDevice                                         |
 243 +-----------+--------+------------+---------------------------------------------------+
 244 | 0x139     | 1      |            | bDeviceClass                                      |
 245 +-----------+--------+------------+---------------------------------------------------+
 246 | 0x13A     | 1      |            | bDeviceSubClass                                   |
 247 +-----------+--------+------------+---------------------------------------------------+
 248 | 0x13B     | 1      |            | bDeviceProtocol                                   |
 249 +-----------+--------+------------+---------------------------------------------------+
 250 | 0x13C     | 1      |            | bConfigurationValue                               |
 251 +-----------+--------+------------+---------------------------------------------------+
 252 | 0x13D     | 1      |            | bNumConfigurations                                |
 253 +-----------+--------+------------+---------------------------------------------------+
 254 | 0x13E     | 1      |            | bNumInterfaces                                    |
 255 +-----------+--------+------------+---------------------------------------------------+
 256
 257 USBIP_CMD_SUBMIT:
 258         Submit an URB
 259
 260 +-----------+--------+------------+---------------------------------------------------+
 261 | Offset    | Length | Value      | Description                                       |
 262 +===========+========+============+===================================================+
 263 | 0         | 4      | 0x00000001 | command: Submit an URB                            |
 264 +-----------+--------+------------+---------------------------------------------------+
 265 | 4         | 4      |            | seqnum: the sequence number of the URB to submit  |
 266 +-----------+--------+------------+---------------------------------------------------+
 267 | 8         | 4      |            | devid                                             |
 268 +-----------+--------+------------+---------------------------------------------------+
 269 | 0xC       | 4      |            | direction:                                        |
 270 |           |        |            |                                                   |
 271 |           |        |            |    - 0: USBIP_DIR_OUT                             |
 272 |           |        |            |    - 1: USBIP_DIR_IN                              |
 273 +-----------+--------+------------+---------------------------------------------------+
 274 | 0x10      | 4      |            | ep: endpoint number, possible values are: 0...15  |
 275 +-----------+--------+------------+---------------------------------------------------+
 276 | 0x14      | 4      |            | transfer_flags: possible values depend on the     |
 277 |           |        |            | URB transfer type, see below                      |
 278 +-----------+--------+------------+---------------------------------------------------+
 279 | 0x18      | 4      |            | transfer_buffer_length                            |
 280 +-----------+--------+------------+---------------------------------------------------+
 281 | 0x1C      | 4      |            | start_frame: specify the selected frame to        |
 282 |           |        |            | transmit an ISO frame, ignored if URB_ISO_ASAP    |
 283 |           |        |            | is specified at transfer_flags                    |
 284 +-----------+--------+------------+---------------------------------------------------+
 285 | 0x20      | 4      |            | number_of_packets: number of ISO packets          |
 286 +-----------+--------+------------+---------------------------------------------------+
 287 | 0x24      | 4      |            | interval: maximum time for the request on the     |
 288 |           |        |            | server-side host controller                       |
 289 +-----------+--------+------------+---------------------------------------------------+
 290 | 0x28      | 8      |            | setup: data bytes for USB setup, filled with      |
 291 |           |        |            | zeros if not used                                 |
 292 +-----------+--------+------------+---------------------------------------------------+
 293 | 0x30      |        |            | URB data. For ISO transfers the padding between   |
 294 |           |        |            | each ISO packets is not transmitted.              |
 295 +-----------+--------+------------+---------------------------------------------------+
 296
 297
 298  +-------------------------+------------+---------+-----------+----------+-------------+
 299  | Allowed transfer_flags  | value      | control | interrupt | bulk     | isochronous |
 300  +=========================+============+=========+===========+==========+=============+
 301  | URB_SHORT_NOT_OK        | 0x00000001 | only in | only in   | only in  | no          |
 302  +-------------------------+------------+---------+-----------+----------+-------------+
 303  | URB_ISO_ASAP            | 0x00000002 | no      | no        | no       | yes         |
 304  +-------------------------+------------+---------+-----------+----------+-------------+
 305  | URB_NO_TRANSFER_DMA_MAP | 0x00000004 | yes     | yes       | yes      | yes         |
 306  +-------------------------+------------+---------+-----------+----------+-------------+
 307  | URB_ZERO_PACKET         | 0x00000040 | no      | no        | only out | no          |
 308  +-------------------------+------------+---------+-----------+----------+-------------+
 309  | URB_NO_INTERRUPT        | 0x00000080 | yes     | yes       | yes      | yes         |
 310  +-------------------------+------------+---------+-----------+----------+-------------+
 311  | URB_FREE_BUFFER         | 0x00000100 | yes     | yes       | yes      | yes         |
 312  +-------------------------+------------+---------+-----------+----------+-------------+
 313  | URB_DIR_MASK            | 0x00000200 | yes     | yes       | yes      | yes         |
 314  +-------------------------+------------+---------+-----------+----------+-------------+
 315
 316
 317 USBIP_RET_SUBMIT:
 318         Reply for submitting an URB
 319
 320 +-----------+--------+------------+---------------------------------------------------+
 321 | Offset    | Length | Value      | Description                                       |
 322 +===========+========+============+===================================================+
 323 | 0         | 4      | 0x00000003 | command                                           |
 324 +-----------+--------+------------+---------------------------------------------------+
 325 | 4         | 4      |            | seqnum: URB sequence number                       |
 326 +-----------+--------+------------+---------------------------------------------------+
 327 | 8         | 4      |            | devid                                             |
 328 +-----------+--------+------------+---------------------------------------------------+
 329 | 0xC       | 4      |            | direction:                                        |
 330 |           |        |            |                                                   |
 331 |           |        |            |    - 0: USBIP_DIR_OUT                             |
 332 |           |        |            |    - 1: USBIP_DIR_IN                              |
 333 +-----------+--------+------------+---------------------------------------------------+
 334 | 0x10      | 4      |            | ep: endpoint number                               |
 335 +-----------+--------+------------+---------------------------------------------------+
 336 | 0x14      | 4      |            | status: zero for successful URB transaction,      |
 337 |           |        |            | otherwise some kind of error happened.            |
 338 +-----------+--------+------------+---------------------------------------------------+
 339 | 0x18      | 4      | n          | actual_length: number of URB data bytes           |
 340 +-----------+--------+------------+---------------------------------------------------+
 341 | 0x1C      | 4      |            | start_frame: for an ISO frame the actually        |
 342 |           |        |            | selected frame for transmit.                      |
 343 +-----------+--------+------------+---------------------------------------------------+
 344 | 0x20      | 4      |            | number_of_packets                                 |
 345 +-----------+--------+------------+---------------------------------------------------+
 346 | 0x24      | 4      |            | error_count                                       |
 347 +-----------+--------+------------+---------------------------------------------------+
 348 | 0x28      | 8      |            | setup: data bytes for USB setup, filled with      |
 349 |           |        |            | zeros if not used                                 |
 350 +-----------+--------+------------+---------------------------------------------------+
 351 | 0x30      | n      |            | URB data bytes. For ISO transfers the padding     |
 352 |           |        |            | between each ISO packets is not transmitted.      |
 353 +-----------+--------+------------+---------------------------------------------------+
 354
 355 USBIP_CMD_UNLINK:
 356         Unlink an URB
 357
 358 +-----------+--------+------------+---------------------------------------------------+
 359 | Offset    | Length | Value      | Description                                       |
 360 +===========+========+============+===================================================+
 361 | 0         | 4      | 0x00000002 | command: URB unlink command                       |
 362 +-----------+--------+------------+---------------------------------------------------+
 363 | 4         | 4      |            | seqnum: URB sequence number to unlink:            |
 364 |           |        |            |                                                   |
 365 |           |        |            | FIXME:                                            |
 366 |           |        |            |    is this so?                                    |
 367 +-----------+--------+------------+---------------------------------------------------+
 368 | 8         | 4      |            | devid                                             |
 369 +-----------+--------+------------+---------------------------------------------------+
 370 | 0xC       | 4      |            | direction:                                        |
 371 |           |        |            |                                                   |
 372 |           |        |            |    - 0: USBIP_DIR_OUT                             |
 373 |           |        |            |    - 1: USBIP_DIR_IN                              |
 374 +-----------+--------+------------+---------------------------------------------------+
 375 | 0x10      | 4      |            | ep: endpoint number: zero                         |
 376 +-----------+--------+------------+---------------------------------------------------+
 377 | 0x14      | 4      |            | seqnum: the URB sequence number given previously  |
 378 |           |        |            | at USBIP_CMD_SUBMIT.seqnum field                  |
 379 +-----------+--------+------------+---------------------------------------------------+
 380 | 0x30      | n      |            | URB data bytes. For ISO transfers the padding     |
 381 |           |        |            | between each ISO packets is not transmitted.      |
 382 +-----------+--------+------------+---------------------------------------------------+
 383
 384 USBIP_RET_UNLINK:
 385         Reply for URB unlink
 386
 387 +-----------+--------+------------+---------------------------------------------------+
 388 | Offset    | Length | Value      | Description                                       |
 389 +===========+========+============+===================================================+
 390 | 0         | 4      | 0x00000004 | command: reply for the URB unlink command         |
 391 +-----------+--------+------------+---------------------------------------------------+
 392 | 4         | 4      |            | seqnum: the unlinked URB sequence number          |
 393 +-----------+--------+------------+---------------------------------------------------+
 394 | 8         | 4      |            | devid                                             |
 395 +-----------+--------+------------+---------------------------------------------------+
 396 | 0xC       | 4      |            | direction:                                        |
 397 |           |        |            |                                                   |
 398 |           |        |            |    - 0: USBIP_DIR_OUT                             |
 399 |           |        |            |    - 1: USBIP_DIR_IN                              |
 400 +-----------+--------+------------+---------------------------------------------------+
 401 | 0x10      | 4      |            | ep: endpoint number                               |
 402 +-----------+--------+------------+---------------------------------------------------+
 403 | 0x14      | 4      |            | status: This is the value contained in the        |
 404 |           |        |            | urb->status in the URB completition handler.      |
 405 |           |        |            |                                                   |
 406 |           |        |            | FIXME:                                            |
 407 |           |        |            |      a better explanation needed.                 |
 408 +-----------+--------+------------+---------------------------------------------------+
 409 | 0x30      | n      |            | URB data bytes. For ISO transfers the padding     |
 410 |           |        |            | between each ISO packets is not transmitted.      |
 411 +-----------+--------+------------+---------------------------------------------------+