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diff --git a/Documentation/usb/usbip_protocol.rst b/Documentation/usb/usbip_protocol.rst new file mode 100644 index 000000000..adc158967 --- /dev/null +++ b/Documentation/usb/usbip_protocol.rst @@ -0,0 +1,452 @@ +=============== +USB/IP protocol +=============== + +Architecture +============ + +The USB/IP protocol follows a server/client architecture. The server exports the +USB devices and the clients import 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 to 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 to 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) | + | <---------------------------------------------- | + | . | + | : | + +For UNLINK, note that after a successful USBIP_RET_UNLINK, the unlinked URB +submission would not have a corresponding USBIP_RET_SUBMIT (this is explained in +function stub_recv_cmd_unlink of drivers/usb/usbip/stub_rx.c). + +:: + + virtual host controller usb host + "client" "server" + (imports USB devices) (exports USB devices) + | | + | USBIP_CMD_SUBMIT(seqnum = p) | + | ----------------------------------------------> | + | | + | USBIP_CMD_UNLINK | + | (seqnum = p+1, unlink_seqnum = p) | + | ----------------------------------------------> | + | | + | USBIP_RET_UNLINK | + | (seqnum = p+1, status = -ECONNRESET) | + | <---------------------------------------------- | + | | + | Note: No USBIP_RET_SUBMIT(seqnum = p) | + | <--X---X---X---X---X---X---X---X---X---X---X--- | + | . | + | : | + | | + | USBIP_CMD_SUBMIT(seqnum = q) | + | ----------------------------------------------> | + | | + | USBIP_RET_SUBMIT(seqnum = q) | + | <---------------------------------------------- | + | | + | USBIP_CMD_UNLINK | + | (seqnum = q+1, unlink_seqnum = q) | + | ----------------------------------------------> | + | | + | USBIP_RET_UNLINK | + | (seqnum = q+1, status = 0) | + | <---------------------------------------------- | + | | + +The fields are in network (big endian) byte order meaning that the most significant +byte (MSB) is stored at the lowest address. + +Protocol Version +================ + +The documented USBIP version is v1.1.1. The binary representation of this +version in message headers is 0x0111. + +This is defined in tools/usb/usbip/configure.ac + +Message Format +============== + +OP_REQ_DEVLIST: + Retrieve the list of exported USB devices. + ++-----------+--------+------------+---------------------------------------------------+ +| Offset | Length | Value | Description | ++===========+========+============+===================================================+ +| 0 | 2 | | USBIP version | ++-----------+--------+------------+---------------------------------------------------+ +| 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 | | USBIP version | ++-----------+--------+------------+---------------------------------------------------+ +| 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 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 path field. | +| m_(i-1)*4 | | | | ++-----------+--------+------------+---------------------------------------------------+ + +OP_REQ_IMPORT: + Request to import (attach) a remote USB device. + ++-----------+--------+------------+---------------------------------------------------+ +| Offset | Length | Value | Description | ++===========+========+============+===================================================+ +| 0 | 2 | | USBIP version | ++-----------+--------+------------+---------------------------------------------------+ +| 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 | | USBIP version | ++-----------+--------+------------+---------------------------------------------------+ +| 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 | ++-----------+--------+------------+---------------------------------------------------+ + +The following four commands have a common basic header called +'usbip_header_basic', and their headers, called 'usbip_header' (before +transfer_buffer payload), have the same length, therefore paddings are needed. + +usbip_header_basic: + ++-----------+--------+---------------------------------------------------+ +| Offset | Length | Description | ++===========+========+===================================================+ +| 0 | 4 | command | ++-----------+--------+---------------------------------------------------+ +| 4 | 4 | seqnum: sequential number that identifies requests| +| | | and corresponding responses; | +| | | incremented per connection | ++-----------+--------+---------------------------------------------------+ +| 8 | 4 | devid: specifies a remote USB device uniquely | +| | | instead of busnum and devnum; | +| | | for client (request), this value is | +| | | ((busnum << 16) | devnum); | +| | | for server (response), this shall be set to 0 | ++-----------+--------+---------------------------------------------------+ +| 0xC | 4 | direction: | +| | | | +| | | - 0: USBIP_DIR_OUT | +| | | - 1: USBIP_DIR_IN | +| | | | +| | | only used by client, for server this shall be 0 | ++-----------+--------+---------------------------------------------------+ +| 0x10 | 4 | ep: endpoint number | +| | | only used by client, for server this shall be 0; | +| | | for UNLINK, this shall be 0 | ++-----------+--------+---------------------------------------------------+ + +USBIP_CMD_SUBMIT: + Submit an URB + ++-----------+--------+---------------------------------------------------+ +| Offset | Length | Description | ++===========+========+===================================================+ +| 0 | 20 | usbip_header_basic, 'command' shall be 0x00000001 | ++-----------+--------+---------------------------------------------------+ +| 0x14 | 4 | transfer_flags: possible values depend on the | +| | | USBIP_URB transfer_flags. | +| | | Refer to include/uapi/linux/usbip.h and | +| | | Documentation/driver-api/usb/URB.rst. | +| | | Refer to usbip_pack_cmd_submit() and | +| | | tweak_transfer_flags() in drivers/usb/usbip/ | +| | | usbip_common.c. | ++-----------+--------+---------------------------------------------------+ +| 0x18 | 4 | transfer_buffer_length: | +| | | use URB transfer_buffer_length | ++-----------+--------+---------------------------------------------------+ +| 0x1C | 4 | start_frame: use URB start_frame; | +| | | initial frame for ISO transfer; | +| | | shall be set to 0 if not ISO transfer | ++-----------+--------+---------------------------------------------------+ +| 0x20 | 4 | number_of_packets: number of ISO packets; | +| | | shall be set to 0xffffffff if not ISO transfer | ++-----------+--------+---------------------------------------------------+ +| 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 | n | transfer_buffer. | +| | | If direction is USBIP_DIR_OUT then n equals | +| | | transfer_buffer_length; otherwise n equals 0. | +| | | For ISO transfers the padding between each ISO | +| | | packets is not transmitted. | ++-----------+--------+---------------------------------------------------+ +| 0x30+n | m | iso_packet_descriptor | ++-----------+--------+---------------------------------------------------+ + +USBIP_RET_SUBMIT: + Reply for submitting an URB + ++-----------+--------+---------------------------------------------------+ +| Offset | Length | Description | ++===========+========+===================================================+ +| 0 | 20 | usbip_header_basic, 'command' shall be 0x00000003 | ++-----------+--------+---------------------------------------------------+ +| 0x14 | 4 | status: zero for successful URB transaction, | +| | | otherwise some kind of error happened. | ++-----------+--------+---------------------------------------------------+ +| 0x18 | 4 | actual_length: number of URB data bytes; | +| | | use URB actual_length | ++-----------+--------+---------------------------------------------------+ +| 0x1C | 4 | start_frame: use URB start_frame; | +| | | initial frame for ISO transfer; | +| | | shall be set to 0 if not ISO transfer | ++-----------+--------+---------------------------------------------------+ +| 0x20 | 4 | number_of_packets: number of ISO packets; | +| | | shall be set to 0xffffffff if not ISO transfer | ++-----------+--------+---------------------------------------------------+ +| 0x24 | 4 | error_count | ++-----------+--------+---------------------------------------------------+ +| 0x28 | 8 | padding, shall be set to 0 | ++-----------+--------+---------------------------------------------------+ +| 0x30 | n | transfer_buffer. | +| | | If direction is USBIP_DIR_IN then n equals | +| | | actual_length; otherwise n equals 0. | +| | | For ISO transfers the padding between each ISO | +| | | packets is not transmitted. | ++-----------+--------+---------------------------------------------------+ +| 0x30+n | m | iso_packet_descriptor | ++-----------+--------+---------------------------------------------------+ + +USBIP_CMD_UNLINK: + Unlink an URB + ++-----------+--------+---------------------------------------------------+ +| Offset | Length | Description | ++===========+========+===================================================+ +| 0 | 20 | usbip_header_basic, 'command' shall be 0x00000002 | ++-----------+--------+---------------------------------------------------+ +| 0x14 | 4 | unlink_seqnum, of the SUBMIT request to unlink | ++-----------+--------+---------------------------------------------------+ +| 0x18 | 24 | padding, shall be set to 0 | ++-----------+--------+---------------------------------------------------+ + +USBIP_RET_UNLINK: + Reply for URB unlink + ++-----------+--------+---------------------------------------------------+ +| Offset | Length | Description | ++===========+========+===================================================+ +| 0 | 20 | usbip_header_basic, 'command' shall be 0x00000004 | ++-----------+--------+---------------------------------------------------+ +| 0x14 | 4 | status: This is similar to the status of | +| | | USBIP_RET_SUBMIT (share the same memory offset). | +| | | When UNLINK is successful, status is -ECONNRESET; | +| | | when USBIP_CMD_UNLINK is after USBIP_RET_SUBMIT | +| | | status is 0 | ++-----------+--------+---------------------------------------------------+ +| 0x18 | 24 | padding, shall be set to 0 | ++-----------+--------+---------------------------------------------------+ + +EXAMPLE +======= + + The following data is captured from wire with Human Interface Devices (HID) + payload + +:: + + CmdIntrIN: 00000001 00000d05 0001000f 00000001 00000001 00000200 00000040 ffffffff 00000000 00000004 00000000 00000000 + CmdIntrOUT: 00000001 00000d06 0001000f 00000000 00000001 00000000 00000040 ffffffff 00000000 00000004 00000000 00000000 + ffffffff860008a784ce5ae212376300000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000 + RetIntrOut: 00000003 00000d06 00000000 00000000 00000000 00000000 00000040 ffffffff 00000000 00000000 00000000 00000000 + RetIntrIn: 00000003 00000d05 00000000 00000000 00000000 00000000 00000040 ffffffff 00000000 00000000 00000000 00000000 + ffffffff860011a784ce5ae2123763612891b1020100000400000000000000000000000000000000000000000000000000000000000000000000000000000000 |