| xj | b04a402 | 2021-11-25 15:01:52 +0800 | [diff] [blame] | 1 | PRELIMINARY DRAFT, MAY CONTAIN MISTAKES! |
| 2 | 28 Jun 2011 |
| 3 | |
| 4 | The USB/IP protocol follows a server/client architecture. The server exports the |
| 5 | USB devices and the clients imports them. The device driver for the exported |
| 6 | USB device runs on the client machine. |
| 7 | |
| 8 | The client may ask for the list of the exported USB devices. To get the list the |
| 9 | client opens a TCP/IP connection towards the server, and sends an OP_REQ_DEVLIST |
| 10 | packet on top of the TCP/IP connection (so the actual OP_REQ_DEVLIST may be sent |
| 11 | in one or more pieces at the low level transport layer). The server sends back |
| 12 | the OP_REP_DEVLIST packet which lists the exported USB devices. Finally the |
| 13 | TCP/IP connection is closed. |
| 14 | |
| 15 | virtual host controller usb host |
| 16 | "client" "server" |
| 17 | (imports USB devices) (exports USB devices) |
| 18 | | | |
| 19 | | OP_REQ_DEVLIST | |
| 20 | | ----------------------------------------------> | |
| 21 | | | |
| 22 | | OP_REP_DEVLIST | |
| 23 | | <---------------------------------------------- | |
| 24 | | | |
| 25 | |
| 26 | Once the client knows the list of exported USB devices it may decide to use one |
| 27 | of them. First the client opens a TCP/IP connection towards the server and |
| 28 | sends an OP_REQ_IMPORT packet. The server replies with OP_REP_IMPORT. If the |
| 29 | import was successful the TCP/IP connection remains open and will be used |
| 30 | to transfer the URB traffic between the client and the server. The client may |
| 31 | send two types of packets: the USBIP_CMD_SUBMIT to submit an URB, and |
| 32 | USBIP_CMD_UNLINK to unlink a previously submitted URB. The answers of the |
| 33 | server may be USBIP_RET_SUBMIT and USBIP_RET_UNLINK respectively. |
| 34 | |
| 35 | virtual host controller usb host |
| 36 | "client" "server" |
| 37 | (imports USB devices) (exports USB devices) |
| 38 | | | |
| 39 | | OP_REQ_IMPORT | |
| 40 | | ----------------------------------------------> | |
| 41 | | | |
| 42 | | OP_REP_IMPORT | |
| 43 | | <---------------------------------------------- | |
| 44 | | | |
| 45 | | | |
| 46 | | USBIP_CMD_SUBMIT(seqnum = n) | |
| 47 | | ----------------------------------------------> | |
| 48 | | | |
| 49 | | USBIP_RET_SUBMIT(seqnum = n) | |
| 50 | | <---------------------------------------------- | |
| 51 | | . | |
| 52 | | : | |
| 53 | | | |
| 54 | | USBIP_CMD_SUBMIT(seqnum = m) | |
| 55 | | ----------------------------------------------> | |
| 56 | | | |
| 57 | | USBIP_CMD_SUBMIT(seqnum = m+1) | |
| 58 | | ----------------------------------------------> | |
| 59 | | | |
| 60 | | USBIP_CMD_SUBMIT(seqnum = m+2) | |
| 61 | | ----------------------------------------------> | |
| 62 | | | |
| 63 | | USBIP_RET_SUBMIT(seqnum = m) | |
| 64 | | <---------------------------------------------- | |
| 65 | | | |
| 66 | | USBIP_CMD_SUBMIT(seqnum = m+3) | |
| 67 | | ----------------------------------------------> | |
| 68 | | | |
| 69 | | USBIP_RET_SUBMIT(seqnum = m+1) | |
| 70 | | <---------------------------------------------- | |
| 71 | | | |
| 72 | | USBIP_CMD_SUBMIT(seqnum = m+4) | |
| 73 | | ----------------------------------------------> | |
| 74 | | | |
| 75 | | USBIP_RET_SUBMIT(seqnum = m+2) | |
| 76 | | <---------------------------------------------- | |
| 77 | | . | |
| 78 | | : | |
| 79 | | | |
| 80 | | USBIP_CMD_UNLINK | |
| 81 | | ----------------------------------------------> | |
| 82 | | | |
| 83 | | USBIP_RET_UNLINK | |
| 84 | | <---------------------------------------------- | |
| 85 | | | |
| 86 | |
| 87 | The fields are in network (big endian) byte order meaning that the most significant |
| 88 | byte (MSB) is stored at the lowest address. |
| 89 | |
| 90 | |
| 91 | OP_REQ_DEVLIST: Retrieve the list of exported USB devices. |
| 92 | |
| 93 | Offset | Length | Value | Description |
| 94 | -----------+--------+------------+--------------------------------------------------- |
| 95 | 0 | 2 | 0x0100 | Binary-coded decimal USBIP version number: v1.0.0 |
| 96 | -----------+--------+------------+--------------------------------------------------- |
| 97 | 2 | 2 | 0x8005 | Command code: Retrieve the list of exported USB |
| 98 | | | | devices. |
| 99 | -----------+--------+------------+--------------------------------------------------- |
| 100 | 4 | 4 | 0x00000000 | Status: unused, shall be set to 0 |
| 101 | |
| 102 | OP_REP_DEVLIST: Reply with the list of exported USB devices. |
| 103 | |
| 104 | Offset | Length | Value | Description |
| 105 | -----------+--------+------------+--------------------------------------------------- |
| 106 | 0 | 2 | 0x0100 | Binary-coded decimal USBIP version number: v1.0.0. |
| 107 | -----------+--------+------------+--------------------------------------------------- |
| 108 | 2 | 2 | 0x0005 | Reply code: The list of exported USB devices. |
| 109 | -----------+--------+------------+--------------------------------------------------- |
| 110 | 4 | 4 | 0x00000000 | Status: 0 for OK |
| 111 | -----------+--------+------------+--------------------------------------------------- |
| 112 | 8 | 4 | n | Number of exported devices: 0 means no exported |
| 113 | | | | devices. |
| 114 | -----------+--------+------------+--------------------------------------------------- |
| 115 | 0x0C | | | From now on the exported n devices are described, |
| 116 | | | | if any. If no devices are exported the message |
| 117 | | | | ends with the previous "number of exported |
| 118 | | | | devices" field. |
| 119 | -----------+--------+------------+--------------------------------------------------- |
| 120 | | 256 | | path: Path of the device on the host exporting the |
| 121 | | | | USB device, string closed with zero byte, e.g. |
| 122 | | | | "/sys/devices/pci0000:00/0000:00:1d.1/usb3/3-2" |
| 123 | | | | The unused bytes shall be filled with zero |
| 124 | | | | bytes. |
| 125 | -----------+--------+------------+--------------------------------------------------- |
| 126 | 0x10C | 32 | | busid: Bus ID of the exported device, string |
| 127 | | | | closed with zero byte, e.g. "3-2". The unused |
| 128 | | | | bytes shall be filled with zero bytes. |
| 129 | -----------+--------+------------+--------------------------------------------------- |
| 130 | 0x12C | 4 | | busnum |
| 131 | -----------+--------+------------+--------------------------------------------------- |
| 132 | 0x130 | 4 | | devnum |
| 133 | -----------+--------+------------+--------------------------------------------------- |
| 134 | 0x134 | 4 | | speed |
| 135 | -----------+--------+------------+--------------------------------------------------- |
| 136 | 0x138 | 2 | | idVendor |
| 137 | -----------+--------+------------+--------------------------------------------------- |
| 138 | 0x13A | 2 | | idProduct |
| 139 | -----------+--------+------------+--------------------------------------------------- |
| 140 | 0x13C | 2 | | bcdDevice |
| 141 | -----------+--------+------------+--------------------------------------------------- |
| 142 | 0x13E | 1 | | bDeviceClass |
| 143 | -----------+--------+------------+--------------------------------------------------- |
| 144 | 0x13F | 1 | | bDeviceSubClass |
| 145 | -----------+--------+------------+--------------------------------------------------- |
| 146 | 0x140 | 1 | | bDeviceProtocol |
| 147 | -----------+--------+------------+--------------------------------------------------- |
| 148 | 0x141 | 1 | | bConfigurationValue |
| 149 | -----------+--------+------------+--------------------------------------------------- |
| 150 | 0x142 | 1 | | bNumConfigurations |
| 151 | -----------+--------+------------+--------------------------------------------------- |
| 152 | 0x143 | 1 | | bNumInterfaces |
| 153 | -----------+--------+------------+--------------------------------------------------- |
| 154 | 0x144 | | m_0 | From now on each interface is described, all |
| 155 | | | | together bNumInterfaces times, with the |
| 156 | | | | the following 4 fields: |
| 157 | -----------+--------+------------+--------------------------------------------------- |
| 158 | | 1 | | bInterfaceClass |
| 159 | -----------+--------+------------+--------------------------------------------------- |
| 160 | 0x145 | 1 | | bInterfaceSubClass |
| 161 | -----------+--------+------------+--------------------------------------------------- |
| 162 | 0x146 | 1 | | bInterfaceProtocol |
| 163 | -----------+--------+------------+--------------------------------------------------- |
| 164 | 0x147 | 1 | | padding byte for alignment, shall be set to zero |
| 165 | -----------+--------+------------+--------------------------------------------------- |
| 166 | 0xC + | | | The second exported USB device starts at i=1 |
| 167 | i*0x138 + | | | with the busid field. |
| 168 | m_(i-1)*4 | | | |
| 169 | |
| 170 | OP_REQ_IMPORT: Request to import (attach) a remote USB device. |
| 171 | |
| 172 | Offset | Length | Value | Description |
| 173 | -----------+--------+------------+--------------------------------------------------- |
| 174 | 0 | 2 | 0x0100 | Binary-coded decimal USBIP version number: v1.0.0 |
| 175 | -----------+--------+------------+--------------------------------------------------- |
| 176 | 2 | 2 | 0x8003 | Command code: import a remote USB device. |
| 177 | -----------+--------+------------+--------------------------------------------------- |
| 178 | 4 | 4 | 0x00000000 | Status: unused, shall be set to 0 |
| 179 | -----------+--------+------------+--------------------------------------------------- |
| 180 | 8 | 32 | | busid: the busid of the exported device on the |
| 181 | | | | remote host. The possible values are taken |
| 182 | | | | from the message field OP_REP_DEVLIST.busid. |
| 183 | | | | A string closed with zero, the unused bytes |
| 184 | | | | shall be filled with zeros. |
| 185 | -----------+--------+------------+--------------------------------------------------- |
| 186 | |
| 187 | OP_REP_IMPORT: Reply to import (attach) a remote USB device. |
| 188 | |
| 189 | Offset | Length | Value | Description |
| 190 | -----------+--------+------------+--------------------------------------------------- |
| 191 | 0 | 2 | 0x0100 | Binary-coded decimal USBIP version number: v1.0.0 |
| 192 | -----------+--------+------------+--------------------------------------------------- |
| 193 | 2 | 2 | 0x0003 | Reply code: Reply to import. |
| 194 | -----------+--------+------------+--------------------------------------------------- |
| 195 | 4 | 4 | 0x00000000 | Status: 0 for OK |
| 196 | | | | 1 for error |
| 197 | -----------+--------+------------+--------------------------------------------------- |
| 198 | 8 | | | From now on comes the details of the imported |
| 199 | | | | device, if the previous status field was OK (0), |
| 200 | | | | otherwise the reply ends with the status field. |
| 201 | -----------+--------+------------+--------------------------------------------------- |
| 202 | | 256 | | path: Path of the device on the host exporting the |
| 203 | | | | USB device, string closed with zero byte, e.g. |
| 204 | | | | "/sys/devices/pci0000:00/0000:00:1d.1/usb3/3-2" |
| 205 | | | | The unused bytes shall be filled with zero |
| 206 | | | | bytes. |
| 207 | -----------+--------+------------+--------------------------------------------------- |
| 208 | 0x108 | 32 | | busid: Bus ID of the exported device, string |
| 209 | | | | closed with zero byte, e.g. "3-2". The unused |
| 210 | | | | bytes shall be filled with zero bytes. |
| 211 | -----------+--------+------------+--------------------------------------------------- |
| 212 | 0x128 | 4 | | busnum |
| 213 | -----------+--------+------------+--------------------------------------------------- |
| 214 | 0x12C | 4 | | devnum |
| 215 | -----------+--------+------------+--------------------------------------------------- |
| 216 | 0x130 | 4 | | speed |
| 217 | -----------+--------+------------+--------------------------------------------------- |
| 218 | 0x134 | 2 | | idVendor |
| 219 | -----------+--------+------------+--------------------------------------------------- |
| 220 | 0x136 | 2 | | idProduct |
| 221 | -----------+--------+------------+--------------------------------------------------- |
| 222 | 0x138 | 2 | | bcdDevice |
| 223 | -----------+--------+------------+--------------------------------------------------- |
| 224 | 0x139 | 1 | | bDeviceClass |
| 225 | -----------+--------+------------+--------------------------------------------------- |
| 226 | 0x13A | 1 | | bDeviceSubClass |
| 227 | -----------+--------+------------+--------------------------------------------------- |
| 228 | 0x13B | 1 | | bDeviceProtocol |
| 229 | -----------+--------+------------+--------------------------------------------------- |
| 230 | 0x13C | 1 | | bConfigurationValue |
| 231 | -----------+--------+------------+--------------------------------------------------- |
| 232 | 0x13D | 1 | | bNumConfigurations |
| 233 | -----------+--------+------------+--------------------------------------------------- |
| 234 | 0x13E | 1 | | bNumInterfaces |
| 235 | |
| 236 | USBIP_CMD_SUBMIT: Submit an URB |
| 237 | |
| 238 | Offset | Length | Value | Description |
| 239 | -----------+--------+------------+--------------------------------------------------- |
| 240 | 0 | 4 | 0x00000001 | command: Submit an URB |
| 241 | -----------+--------+------------+--------------------------------------------------- |
| 242 | 4 | 4 | | seqnum: the sequence number of the URB to submit |
| 243 | -----------+--------+------------+--------------------------------------------------- |
| 244 | 8 | 4 | | devid |
| 245 | -----------+--------+------------+--------------------------------------------------- |
| 246 | 0xC | 4 | | direction: 0: USBIP_DIR_OUT |
| 247 | | | | 1: USBIP_DIR_IN |
| 248 | -----------+--------+------------+--------------------------------------------------- |
| 249 | 0x10 | 4 | | ep: endpoint number, possible values are: 0...15 |
| 250 | -----------+--------+------------+--------------------------------------------------- |
| 251 | 0x14 | 4 | | transfer_flags: possible values depend on the |
| 252 | | | | URB transfer type, see below |
| 253 | -----------+--------+------------+--------------------------------------------------- |
| 254 | 0x18 | 4 | | transfer_buffer_length |
| 255 | -----------+--------+------------+--------------------------------------------------- |
| 256 | 0x1C | 4 | | start_frame: specify the selected frame to |
| 257 | | | | transmit an ISO frame, ignored if URB_ISO_ASAP |
| 258 | | | | is specified at transfer_flags |
| 259 | -----------+--------+------------+--------------------------------------------------- |
| 260 | 0x20 | 4 | | number_of_packets: number of ISO packets |
| 261 | -----------+--------+------------+--------------------------------------------------- |
| 262 | 0x24 | 4 | | interval: maximum time for the request on the |
| 263 | | | | server-side host controller |
| 264 | -----------+--------+------------+--------------------------------------------------- |
| 265 | 0x28 | 8 | | setup: data bytes for USB setup, filled with |
| 266 | | | | zeros if not used |
| 267 | -----------+--------+------------+--------------------------------------------------- |
| 268 | 0x30 | | | URB data. For ISO transfers the padding between |
| 269 | | | | each ISO packets is not transmitted. |
| 270 | |
| 271 | |
| 272 | Allowed transfer_flags | value | control | interrupt | bulk | isochronous |
| 273 | -------------------------+------------+---------+-----------+----------+------------- |
| 274 | URB_SHORT_NOT_OK | 0x00000001 | only in | only in | only in | no |
| 275 | URB_ISO_ASAP | 0x00000002 | no | no | no | yes |
| 276 | URB_NO_TRANSFER_DMA_MAP | 0x00000004 | yes | yes | yes | yes |
| 277 | URB_ZERO_PACKET | 0x00000040 | no | no | only out | no |
| 278 | URB_NO_INTERRUPT | 0x00000080 | yes | yes | yes | yes |
| 279 | URB_FREE_BUFFER | 0x00000100 | yes | yes | yes | yes |
| 280 | URB_DIR_MASK | 0x00000200 | yes | yes | yes | yes |
| 281 | |
| 282 | |
| 283 | USBIP_RET_SUBMIT: Reply for submitting an URB |
| 284 | |
| 285 | Offset | Length | Value | Description |
| 286 | -----------+--------+------------+--------------------------------------------------- |
| 287 | 0 | 4 | 0x00000003 | command |
| 288 | -----------+--------+------------+--------------------------------------------------- |
| 289 | 4 | 4 | | seqnum: URB sequence number |
| 290 | -----------+--------+------------+--------------------------------------------------- |
| 291 | 8 | 4 | | devid |
| 292 | -----------+--------+------------+--------------------------------------------------- |
| 293 | 0xC | 4 | | direction: 0: USBIP_DIR_OUT |
| 294 | | | | 1: USBIP_DIR_IN |
| 295 | -----------+--------+------------+--------------------------------------------------- |
| 296 | 0x10 | 4 | | ep: endpoint number |
| 297 | -----------+--------+------------+--------------------------------------------------- |
| 298 | 0x14 | 4 | | status: zero for successful URB transaction, |
| 299 | | | | otherwise some kind of error happened. |
| 300 | -----------+--------+------------+--------------------------------------------------- |
| 301 | 0x18 | 4 | n | actual_length: number of URB data bytes |
| 302 | -----------+--------+------------+--------------------------------------------------- |
| 303 | 0x1C | 4 | | start_frame: for an ISO frame the actually |
| 304 | | | | selected frame for transmit. |
| 305 | -----------+--------+------------+--------------------------------------------------- |
| 306 | 0x20 | 4 | | number_of_packets |
| 307 | -----------+--------+------------+--------------------------------------------------- |
| 308 | 0x24 | 4 | | error_count |
| 309 | -----------+--------+------------+--------------------------------------------------- |
| 310 | 0x28 | 8 | | setup: data bytes for USB setup, filled with |
| 311 | | | | zeros if not used |
| 312 | -----------+--------+------------+--------------------------------------------------- |
| 313 | 0x30 | n | | URB data bytes. For ISO transfers the padding |
| 314 | | | | between each ISO packets is not transmitted. |
| 315 | |
| 316 | USBIP_CMD_UNLINK: Unlink an URB |
| 317 | |
| 318 | Offset | Length | Value | Description |
| 319 | -----------+--------+------------+--------------------------------------------------- |
| 320 | 0 | 4 | 0x00000002 | command: URB unlink command |
| 321 | -----------+--------+------------+--------------------------------------------------- |
| 322 | 4 | 4 | | seqnum: URB sequence number to unlink: FIXME: is this so? |
| 323 | -----------+--------+------------+--------------------------------------------------- |
| 324 | 8 | 4 | | devid |
| 325 | -----------+--------+------------+--------------------------------------------------- |
| 326 | 0xC | 4 | | direction: 0: USBIP_DIR_OUT |
| 327 | | | | 1: USBIP_DIR_IN |
| 328 | -----------+--------+------------+--------------------------------------------------- |
| 329 | 0x10 | 4 | | ep: endpoint number: zero |
| 330 | -----------+--------+------------+--------------------------------------------------- |
| 331 | 0x14 | 4 | | seqnum: the URB sequence number given previously |
| 332 | | | | at USBIP_CMD_SUBMIT.seqnum field |
| 333 | -----------+--------+------------+--------------------------------------------------- |
| 334 | 0x30 | n | | URB data bytes. For ISO transfers the padding |
| 335 | | | | between each ISO packets is not transmitted. |
| 336 | |
| 337 | USBIP_RET_UNLINK: Reply for URB unlink |
| 338 | |
| 339 | Offset | Length | Value | Description |
| 340 | -----------+--------+------------+--------------------------------------------------- |
| 341 | 0 | 4 | 0x00000004 | command: reply for the URB unlink command |
| 342 | -----------+--------+------------+--------------------------------------------------- |
| 343 | 4 | 4 | | seqnum: the unlinked URB sequence number |
| 344 | -----------+--------+------------+--------------------------------------------------- |
| 345 | 8 | 4 | | devid |
| 346 | -----------+--------+------------+--------------------------------------------------- |
| 347 | 0xC | 4 | | direction: 0: USBIP_DIR_OUT |
| 348 | | | | 1: USBIP_DIR_IN |
| 349 | -----------+--------+------------+--------------------------------------------------- |
| 350 | 0x10 | 4 | | ep: endpoint number |
| 351 | -----------+--------+------------+--------------------------------------------------- |
| 352 | 0x14 | 4 | | status: This is the value contained in the |
| 353 | | | | urb->status in the URB completition handler. |
| 354 | | | | FIXME: a better explanation needed. |
| 355 | -----------+--------+------------+--------------------------------------------------- |
| 356 | 0x30 | n | | URB data bytes. For ISO transfers the padding |
| 357 | | | | between each ISO packets is not transmitted. |