| PRELIMINARY DRAFT, MAY CONTAIN MISTAKES! |
| 28 Jun 2011 |
| |
| The USB/IP protocol follows a server/client architecture. The server exports the |
| USB devices and the clients imports them. The device driver for the exported |
| USB device runs on the client machine. |
| |
| The client may ask for the list of the exported USB devices. To get the list the |
| client opens a TCP/IP connection towards the server, and sends an OP_REQ_DEVLIST |
| packet on top of the TCP/IP connection (so the actual OP_REQ_DEVLIST may be sent |
| in one or more pieces at the low level transport layer). The server sends back |
| the OP_REP_DEVLIST packet which lists the exported USB devices. Finally the |
| TCP/IP connection is closed. |
| |
| virtual host controller usb host |
| "client" "server" |
| (imports USB devices) (exports USB devices) |
| | | |
| | OP_REQ_DEVLIST | |
| | ----------------------------------------------> | |
| | | |
| | OP_REP_DEVLIST | |
| | <---------------------------------------------- | |
| | | |
| |
| Once the client knows the list of exported USB devices it may decide to use one |
| of them. First the client opens a TCP/IP connection towards the server and |
| sends an OP_REQ_IMPORT packet. The server replies with OP_REP_IMPORT. If the |
| import was successful the TCP/IP connection remains open and will be used |
| to transfer the URB traffic between the client and the server. The client may |
| send two types of packets: the USBIP_CMD_SUBMIT to submit an URB, and |
| USBIP_CMD_UNLINK to unlink a previously submitted URB. The answers of the |
| server may be USBIP_RET_SUBMIT and USBIP_RET_UNLINK respectively. |
| |
| virtual host controller usb host |
| "client" "server" |
| (imports USB devices) (exports USB devices) |
| | | |
| | OP_REQ_IMPORT | |
| | ----------------------------------------------> | |
| | | |
| | OP_REP_IMPORT | |
| | <---------------------------------------------- | |
| | | |
| | | |
| | USBIP_CMD_SUBMIT(seqnum = n) | |
| | ----------------------------------------------> | |
| | | |
| | USBIP_RET_SUBMIT(seqnum = n) | |
| | <---------------------------------------------- | |
| | . | |
| | : | |
| | | |
| | USBIP_CMD_SUBMIT(seqnum = m) | |
| | ----------------------------------------------> | |
| | | |
| | USBIP_CMD_SUBMIT(seqnum = m+1) | |
| | ----------------------------------------------> | |
| | | |
| | USBIP_CMD_SUBMIT(seqnum = m+2) | |
| | ----------------------------------------------> | |
| | | |
| | USBIP_RET_SUBMIT(seqnum = m) | |
| | <---------------------------------------------- | |
| | | |
| | USBIP_CMD_SUBMIT(seqnum = m+3) | |
| | ----------------------------------------------> | |
| | | |
| | USBIP_RET_SUBMIT(seqnum = m+1) | |
| | <---------------------------------------------- | |
| | | |
| | USBIP_CMD_SUBMIT(seqnum = m+4) | |
| | ----------------------------------------------> | |
| | | |
| | USBIP_RET_SUBMIT(seqnum = m+2) | |
| | <---------------------------------------------- | |
| | . | |
| | : | |
| | | |
| | USBIP_CMD_UNLINK | |
| | ----------------------------------------------> | |
| | | |
| | USBIP_RET_UNLINK | |
| | <---------------------------------------------- | |
| | | |
| |
| The fields are in network (big endian) byte order meaning that the most significant |
| byte (MSB) is stored at the lowest address. |
| |
| |
| OP_REQ_DEVLIST: Retrieve the list of exported USB devices. |
| |
| Offset | Length | Value | Description |
| -----------+--------+------------+--------------------------------------------------- |
| 0 | 2 | 0x0100 | Binary-coded decimal USBIP version number: v1.0.0 |
| -----------+--------+------------+--------------------------------------------------- |
| 2 | 2 | 0x8005 | Command code: Retrieve the list of exported USB |
| | | | devices. |
| -----------+--------+------------+--------------------------------------------------- |
| 4 | 4 | 0x00000000 | Status: unused, shall be set to 0 |
| |
| OP_REP_DEVLIST: Reply with the list of exported USB devices. |
| |
| Offset | Length | Value | Description |
| -----------+--------+------------+--------------------------------------------------- |
| 0 | 2 | 0x0100 | Binary-coded decimal USBIP version number: v1.0.0. |
| -----------+--------+------------+--------------------------------------------------- |
| 2 | 2 | 0x0005 | Reply code: The list of exported USB devices. |
| -----------+--------+------------+--------------------------------------------------- |
| 4 | 4 | 0x00000000 | Status: 0 for OK |
| -----------+--------+------------+--------------------------------------------------- |
| 8 | 4 | n | Number of exported devices: 0 means no exported |
| | | | devices. |
| -----------+--------+------------+--------------------------------------------------- |
| 0x0C | | | From now on the exported n devices are described, |
| | | | if any. If no devices are exported the message |
| | | | ends with the previous "number of exported |
| | | | devices" field. |
| -----------+--------+------------+--------------------------------------------------- |
| | 256 | | path: Path of the device on the host exporting the |
| | | | USB device, string closed with zero byte, e.g. |
| | | | "/sys/devices/pci0000:00/0000:00:1d.1/usb3/3-2" |
| | | | The unused bytes shall be filled with zero |
| | | | bytes. |
| -----------+--------+------------+--------------------------------------------------- |
| 0x10C | 32 | | busid: Bus ID of the exported device, string |
| | | | closed with zero byte, e.g. "3-2". The unused |
| | | | bytes shall be filled with zero bytes. |
| -----------+--------+------------+--------------------------------------------------- |
| 0x12C | 4 | | busnum |
| -----------+--------+------------+--------------------------------------------------- |
| 0x130 | 4 | | devnum |
| -----------+--------+------------+--------------------------------------------------- |
| 0x134 | 4 | | speed |
| -----------+--------+------------+--------------------------------------------------- |
| 0x138 | 2 | | idVendor |
| -----------+--------+------------+--------------------------------------------------- |
| 0x13A | 2 | | idProduct |
| -----------+--------+------------+--------------------------------------------------- |
| 0x13C | 2 | | bcdDevice |
| -----------+--------+------------+--------------------------------------------------- |
| 0x13E | 1 | | bDeviceClass |
| -----------+--------+------------+--------------------------------------------------- |
| 0x13F | 1 | | bDeviceSubClass |
| -----------+--------+------------+--------------------------------------------------- |
| 0x140 | 1 | | bDeviceProtocol |
| -----------+--------+------------+--------------------------------------------------- |
| 0x141 | 1 | | bConfigurationValue |
| -----------+--------+------------+--------------------------------------------------- |
| 0x142 | 1 | | bNumConfigurations |
| -----------+--------+------------+--------------------------------------------------- |
| 0x143 | 1 | | bNumInterfaces |
| -----------+--------+------------+--------------------------------------------------- |
| 0x144 | | m_0 | From now on each interface is described, all |
| | | | together bNumInterfaces times, with the |
| | | | the following 4 fields: |
| -----------+--------+------------+--------------------------------------------------- |
| | 1 | | bInterfaceClass |
| -----------+--------+------------+--------------------------------------------------- |
| 0x145 | 1 | | bInterfaceSubClass |
| -----------+--------+------------+--------------------------------------------------- |
| 0x146 | 1 | | bInterfaceProtocol |
| -----------+--------+------------+--------------------------------------------------- |
| 0x147 | 1 | | padding byte for alignment, shall be set to zero |
| -----------+--------+------------+--------------------------------------------------- |
| 0xC + | | | The second exported USB device starts at i=1 |
| i*0x138 + | | | with the busid field. |
| m_(i-1)*4 | | | |
| |
| OP_REQ_IMPORT: Request to import (attach) a remote USB device. |
| |
| Offset | Length | Value | Description |
| -----------+--------+------------+--------------------------------------------------- |
| 0 | 2 | 0x0100 | Binary-coded decimal USBIP version number: v1.0.0 |
| -----------+--------+------------+--------------------------------------------------- |
| 2 | 2 | 0x8003 | Command code: import a remote USB device. |
| -----------+--------+------------+--------------------------------------------------- |
| 4 | 4 | 0x00000000 | Status: unused, shall be set to 0 |
| -----------+--------+------------+--------------------------------------------------- |
| 8 | 32 | | busid: the busid of the exported device on the |
| | | | remote host. The possible values are taken |
| | | | from the message field OP_REP_DEVLIST.busid. |
| | | | A string closed with zero, the unused bytes |
| | | | shall be filled with zeros. |
| -----------+--------+------------+--------------------------------------------------- |
| |
| OP_REP_IMPORT: Reply to import (attach) a remote USB device. |
| |
| Offset | Length | Value | Description |
| -----------+--------+------------+--------------------------------------------------- |
| 0 | 2 | 0x0100 | Binary-coded decimal USBIP version number: v1.0.0 |
| -----------+--------+------------+--------------------------------------------------- |
| 2 | 2 | 0x0003 | Reply code: Reply to import. |
| -----------+--------+------------+--------------------------------------------------- |
| 4 | 4 | 0x00000000 | Status: 0 for OK |
| | | | 1 for error |
| -----------+--------+------------+--------------------------------------------------- |
| 8 | | | From now on comes the details of the imported |
| | | | device, if the previous status field was OK (0), |
| | | | otherwise the reply ends with the status field. |
| -----------+--------+------------+--------------------------------------------------- |
| | 256 | | path: Path of the device on the host exporting the |
| | | | USB device, string closed with zero byte, e.g. |
| | | | "/sys/devices/pci0000:00/0000:00:1d.1/usb3/3-2" |
| | | | The unused bytes shall be filled with zero |
| | | | bytes. |
| -----------+--------+------------+--------------------------------------------------- |
| 0x108 | 32 | | busid: Bus ID of the exported device, string |
| | | | closed with zero byte, e.g. "3-2". The unused |
| | | | bytes shall be filled with zero bytes. |
| -----------+--------+------------+--------------------------------------------------- |
| 0x128 | 4 | | busnum |
| -----------+--------+------------+--------------------------------------------------- |
| 0x12C | 4 | | devnum |
| -----------+--------+------------+--------------------------------------------------- |
| 0x130 | 4 | | speed |
| -----------+--------+------------+--------------------------------------------------- |
| 0x134 | 2 | | idVendor |
| -----------+--------+------------+--------------------------------------------------- |
| 0x136 | 2 | | idProduct |
| -----------+--------+------------+--------------------------------------------------- |
| 0x138 | 2 | | bcdDevice |
| -----------+--------+------------+--------------------------------------------------- |
| 0x139 | 1 | | bDeviceClass |
| -----------+--------+------------+--------------------------------------------------- |
| 0x13A | 1 | | bDeviceSubClass |
| -----------+--------+------------+--------------------------------------------------- |
| 0x13B | 1 | | bDeviceProtocol |
| -----------+--------+------------+--------------------------------------------------- |
| 0x13C | 1 | | bConfigurationValue |
| -----------+--------+------------+--------------------------------------------------- |
| 0x13D | 1 | | bNumConfigurations |
| -----------+--------+------------+--------------------------------------------------- |
| 0x13E | 1 | | bNumInterfaces |
| |
| USBIP_CMD_SUBMIT: Submit an URB |
| |
| Offset | Length | Value | Description |
| -----------+--------+------------+--------------------------------------------------- |
| 0 | 4 | 0x00000001 | command: Submit an URB |
| -----------+--------+------------+--------------------------------------------------- |
| 4 | 4 | | seqnum: the sequence number of the URB to submit |
| -----------+--------+------------+--------------------------------------------------- |
| 8 | 4 | | devid |
| -----------+--------+------------+--------------------------------------------------- |
| 0xC | 4 | | direction: 0: USBIP_DIR_OUT |
| | | | 1: USBIP_DIR_IN |
| -----------+--------+------------+--------------------------------------------------- |
| 0x10 | 4 | | ep: endpoint number, possible values are: 0...15 |
| -----------+--------+------------+--------------------------------------------------- |
| 0x14 | 4 | | transfer_flags: possible values depend on the |
| | | | URB transfer type, see below |
| -----------+--------+------------+--------------------------------------------------- |
| 0x18 | 4 | | transfer_buffer_length |
| -----------+--------+------------+--------------------------------------------------- |
| 0x1C | 4 | | start_frame: specify the selected frame to |
| | | | transmit an ISO frame, ignored if URB_ISO_ASAP |
| | | | is specified at transfer_flags |
| -----------+--------+------------+--------------------------------------------------- |
| 0x20 | 4 | | number_of_packets: number of ISO packets |
| -----------+--------+------------+--------------------------------------------------- |
| 0x24 | 4 | | interval: maximum time for the request on the |
| | | | server-side host controller |
| -----------+--------+------------+--------------------------------------------------- |
| 0x28 | 8 | | setup: data bytes for USB setup, filled with |
| | | | zeros if not used |
| -----------+--------+------------+--------------------------------------------------- |
| 0x30 | | | URB data. For ISO transfers the padding between |
| | | | each ISO packets is not transmitted. |
| |
| |
| Allowed transfer_flags | value | control | interrupt | bulk | isochronous |
| -------------------------+------------+---------+-----------+----------+------------- |
| URB_SHORT_NOT_OK | 0x00000001 | only in | only in | only in | no |
| URB_ISO_ASAP | 0x00000002 | no | no | no | yes |
| URB_NO_TRANSFER_DMA_MAP | 0x00000004 | yes | yes | yes | yes |
| URB_ZERO_PACKET | 0x00000040 | no | no | only out | no |
| URB_NO_INTERRUPT | 0x00000080 | yes | yes | yes | yes |
| URB_FREE_BUFFER | 0x00000100 | yes | yes | yes | yes |
| URB_DIR_MASK | 0x00000200 | yes | yes | yes | yes |
| |
| |
| USBIP_RET_SUBMIT: Reply for submitting an URB |
| |
| Offset | Length | Value | Description |
| -----------+--------+------------+--------------------------------------------------- |
| 0 | 4 | 0x00000003 | command |
| -----------+--------+------------+--------------------------------------------------- |
| 4 | 4 | | seqnum: URB sequence number |
| -----------+--------+------------+--------------------------------------------------- |
| 8 | 4 | | devid |
| -----------+--------+------------+--------------------------------------------------- |
| 0xC | 4 | | direction: 0: USBIP_DIR_OUT |
| | | | 1: USBIP_DIR_IN |
| -----------+--------+------------+--------------------------------------------------- |
| 0x10 | 4 | | ep: endpoint number |
| -----------+--------+------------+--------------------------------------------------- |
| 0x14 | 4 | | status: zero for successful URB transaction, |
| | | | otherwise some kind of error happened. |
| -----------+--------+------------+--------------------------------------------------- |
| 0x18 | 4 | n | actual_length: number of URB data bytes |
| -----------+--------+------------+--------------------------------------------------- |
| 0x1C | 4 | | start_frame: for an ISO frame the actually |
| | | | selected frame for transmit. |
| -----------+--------+------------+--------------------------------------------------- |
| 0x20 | 4 | | number_of_packets |
| -----------+--------+------------+--------------------------------------------------- |
| 0x24 | 4 | | error_count |
| -----------+--------+------------+--------------------------------------------------- |
| 0x28 | 8 | | setup: data bytes for USB setup, filled with |
| | | | zeros if not used |
| -----------+--------+------------+--------------------------------------------------- |
| 0x30 | n | | URB data bytes. For ISO transfers the padding |
| | | | between each ISO packets is not transmitted. |
| |
| USBIP_CMD_UNLINK: Unlink an URB |
| |
| Offset | Length | Value | Description |
| -----------+--------+------------+--------------------------------------------------- |
| 0 | 4 | 0x00000002 | command: URB unlink command |
| -----------+--------+------------+--------------------------------------------------- |
| 4 | 4 | | seqnum: URB sequence number to unlink: FIXME: is this so? |
| -----------+--------+------------+--------------------------------------------------- |
| 8 | 4 | | devid |
| -----------+--------+------------+--------------------------------------------------- |
| 0xC | 4 | | direction: 0: USBIP_DIR_OUT |
| | | | 1: USBIP_DIR_IN |
| -----------+--------+------------+--------------------------------------------------- |
| 0x10 | 4 | | ep: endpoint number: zero |
| -----------+--------+------------+--------------------------------------------------- |
| 0x14 | 4 | | seqnum: the URB sequence number given previously |
| | | | at USBIP_CMD_SUBMIT.seqnum field |
| -----------+--------+------------+--------------------------------------------------- |
| 0x30 | n | | URB data bytes. For ISO transfers the padding |
| | | | between each ISO packets is not transmitted. |
| |
| USBIP_RET_UNLINK: Reply for URB unlink |
| |
| Offset | Length | Value | Description |
| -----------+--------+------------+--------------------------------------------------- |
| 0 | 4 | 0x00000004 | command: reply for the URB unlink command |
| -----------+--------+------------+--------------------------------------------------- |
| 4 | 4 | | seqnum: the unlinked URB sequence number |
| -----------+--------+------------+--------------------------------------------------- |
| 8 | 4 | | devid |
| -----------+--------+------------+--------------------------------------------------- |
| 0xC | 4 | | direction: 0: USBIP_DIR_OUT |
| | | | 1: USBIP_DIR_IN |
| -----------+--------+------------+--------------------------------------------------- |
| 0x10 | 4 | | ep: endpoint number |
| -----------+--------+------------+--------------------------------------------------- |
| 0x14 | 4 | | status: This is the value contained in the |
| | | | urb->status in the URB completition handler. |
| | | | FIXME: a better explanation needed. |
| -----------+--------+------------+--------------------------------------------------- |
| 0x30 | n | | URB data bytes. For ISO transfers the padding |
| | | | between each ISO packets is not transmitted. |