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- 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_NO_FSBR | 0x00000020 | yes | no | no | no
- 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.
|