docs: usb: rename files to .rst and add them to drivers-api

While there are a mix of things here, most of the stuff
were written from Kernel developer's PoV. So, add them to
the driver-api book.

A follow up for this patch would be to move documents from
there that are specific to sysadmins, adding them to the
admin-guide.

Signed-off-by: Mauro Carvalho Chehab <mchehab+samsung@kernel.org>
Acked-by: Johan Hovold <johan@kernel.org>
Acked-by: Felipe Balbi <felipe.balbi@linux.intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

1 files changed, 411 insertions, 0 deletions

diff --git a/Documentation/usb/usbip_protocol.rst b/Documentation/usb/usbip_protocol.rst
new file mode 100644
index 000000000000..988c832166cd
--- /dev/null
+++ b/Documentation/usb/usbip_protocol.rst
@@ -0,0 +1,411 @@
+===============
+USB/IP protocol
+===============
+
+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.      |
++-----------+--------+------------+---------------------------------------------------+