    /* SPDX-License-Identifier: MIT */
    /*
     * usbif.h
     *
     * USB I/O interface for Xen guest OSes.
     *
     * Copyright (C) 2009, FUJITSU LABORATORIES LTD.
     * Author: Noboru Iwamatsu <n_iwamatsu@jp.fujitsu.com>
     */

    #ifndef __XEN_PUBLIC_IO_USBIF_H__
    #define __XEN_PUBLIC_IO_USBIF_H__

    #include "ring.h"
    #include "../grant_table.h"

    /*
     * Detailed Interface Description
     * ==============================
     * The pvUSB interface is using a split driver design: a frontend driver in
     * the guest and a backend driver in a driver domain (normally dom0) having
     * access to the physical USB device(s) being passed to the guest.
     *
     * The frontend and backend drivers use XenStore to initiate the connection
     * between them, the I/O activity is handled via two shared ring pages and an
     * event channel. As the interface between frontend and backend is at the USB
     * host connector level, multiple (up to 31) physical USB devices can be
     * handled by a single connection.
     *
     * The Xen pvUSB device name is "qusb", so the frontend's XenStore entries are
     * to be found under "device/qusb", while the backend's XenStore entries are
     * under "backend/<guest-dom-id>/qusb".
     *
     * When a new pvUSB connection is established, the frontend needs to setup the
     * two shared ring pages for communication and the event channel. The ring
     * pages need to be made available to the backend via the grant table
     * interface.
     *
     * One of the shared ring pages is used by the backend to inform the frontend
     * about USB device plug events (device to be added or removed). This is the
     * "conn-ring".
     *
     * The other ring page is used for USB I/O communication (requests and
     * responses). This is the "urb-ring".
     *
     * Feature and Parameter Negotiation
     * =================================
     * The two halves of a Xen pvUSB driver utilize nodes within the XenStore to
     * communicate capabilities and to negotiate operating parameters. This
     * section enumerates these nodes which reside in the respective front and
     * backend portions of the XenStore, following the XenBus convention.
     *
     * Any specified default value is in effect if the corresponding XenBus node
     * is not present in the XenStore.
     *
     * XenStore nodes in sections marked "PRIVATE" are solely for use by the
     * driver side whose XenBus tree contains them.
     *
     *****************************************************************************
     *                            Backend XenBus Nodes
     *****************************************************************************
     *
     *------------------ Backend Device Identification (PRIVATE) ------------------
     *
     * num-ports
     *      Values:         unsigned [1...31]
     *
     *      Number of ports for this (virtual) USB host connector.
     *
     * usb-ver
     *      Values:         unsigned [1...2]
     *
     *      USB version of this host connector: 1 = USB 1.1, 2 = USB 2.0.
     *
     * port/[1...31]
     *      Values:         string
     *
     *      Physical USB device connected to the given port, e.g. "3-1.5".
     *
     *****************************************************************************
     *                            Frontend XenBus Nodes
     *****************************************************************************
     *
     *----------------------- Request Transport Parameters -----------------------
     *
     * event-channel
     *      Values:         unsigned
     *
     *      The identifier of the Xen event channel used to signal activity
     *      in the ring buffer.
     *
     * urb-ring-ref
     *      Values:         unsigned
     *
     *      The Xen grant reference granting permission for the backend to map
     *      the sole page in a single page sized ring buffer. This is the ring
     *      buffer for urb requests.
     *
     * conn-ring-ref
     *      Values:         unsigned
     *
     *      The Xen grant reference granting permission for the backend to map
     *      the sole page in a single page sized ring buffer. This is the ring
     *      buffer for connection/disconnection requests.
     *
     * protocol
     *      Values:         string (XEN_IO_PROTO_ABI_*)
     *      Default Value:  XEN_IO_PROTO_ABI_NATIVE
     *
     *      The machine ABI rules governing the format of all ring request and
     *      response structures.
     *
     * Protocol Description
     * ====================
     *
     *-------------------------- USB device plug events --------------------------
     *
     * USB device plug events are send via the "conn-ring" shared page. As only
     * events are being sent, the respective requests from the frontend to the
     * backend are just dummy ones.
     * The events sent to the frontend have the following layout:
     *         0                1                 2               3        octet
     * +----------------+----------------+----------------+----------------+
     * |               id                |    portnum     |     speed      | 4
     * +----------------+----------------+----------------+----------------+
     *   id - uint16_t, event id (taken from the actual frontend dummy request)
     *   portnum - uint8_t, port number (1 ... 31)
     *   speed - uint8_t, device USBIF_SPEED_*, USBIF_SPEED_NONE == unplug
     *
     * The dummy request:
     *         0                1        octet
     * +----------------+----------------+
     * |               id                | 2
     * +----------------+----------------+
     *   id - uint16_t, guest supplied value (no need for being unique)
     *
     *-------------------------- USB I/O request ---------------------------------
     *
     * A single USB I/O request on the "urb-ring" has the following layout:
     *         0                1                 2               3        octet
     * +----------------+----------------+----------------+----------------+
     * |               id                |         nr_buffer_segs          | 4
     * +----------------+----------------+----------------+----------------+
     * |                               pipe                                | 8
     * +----------------+----------------+----------------+----------------+
     * |         transfer_flags          |          buffer_length          | 12
     * +----------------+----------------+----------------+----------------+
     * |                       request type specific                       | 16
     * |                               data                                | 20
     * +----------------+----------------+----------------+----------------+
     * |                              seg[0]                               | 24
     * |                               data                                | 28
     * +----------------+----------------+----------------+----------------+
     * |/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/|
     * +----------------+----------------+----------------+----------------+
     * |             seg[USBIF_MAX_SEGMENTS_PER_REQUEST - 1]               | 144
     * |                               data                                | 148
     * +----------------+----------------+----------------+----------------+
     * Bit field bit number 0 is always least significant bit, undefined bits must
     * be zero.
     *   id - uint16_t, guest supplied value
     *   nr_buffer_segs - uint16_t, number of segment entries in seg[] array
     *   pipe - uint32_t, bit field with multiple information:
     *     bits 0-4: port request to send to
     *     bit 5: unlink request with specified id (cancel I/O) if set (see below)
     *     bit 7: direction (1 = read from device)
     *     bits 8-14: device number on port
     *     bits 15-18: endpoint of device
     *     bits 30-31: request type: 00 = isochronous, 01 = interrupt,
     *                               10 = control, 11 = bulk
     *   transfer_flags - uint16_t, bit field with processing flags:
     *     bit 0: less data than specified allowed
     *   buffer_length - uint16_t, total length of data
     *   request type specific data - 8 bytes, see below
     *   seg[] - array with 8 byte elements, see below
     *
     * Request type specific data for isochronous request:
     *         0                1                 2               3        octet
     * +----------------+----------------+----------------+----------------+
     * |            interval             |           start_frame           | 4
     * +----------------+----------------+----------------+----------------+
     * |       number_of_packets         |       nr_frame_desc_segs        | 8
     * +----------------+----------------+----------------+----------------+
     *   interval - uint16_t, time interval in msecs between frames
     *   start_frame - uint16_t, start frame number
     *   number_of_packets - uint16_t, number of packets to transfer
     *   nr_frame_desc_segs - uint16_t number of seg[] frame descriptors elements
     *
     * Request type specific data for interrupt request:
     *         0                1                 2               3        octet
     * +----------------+----------------+----------------+----------------+
     * |            interval             |                0                | 4
     * +----------------+----------------+----------------+----------------+
     * |                                 0                                 | 8
     * +----------------+----------------+----------------+----------------+
     *   interval - uint16_t, time in msecs until interruption
     *
     * Request type specific data for control request:
     *         0                1                 2               3        octet
     * +----------------+----------------+----------------+----------------+
     * |                      data of setup packet                         | 4
     * |                                                                   | 8
     * +----------------+----------------+----------------+----------------+
     *
     * Request type specific data for bulk request:
     *         0                1                 2               3        octet
     * +----------------+----------------+----------------+----------------+
     * |                                 0                                 | 4
     * |                                 0                                 | 8
     * +----------------+----------------+----------------+----------------+
     *
     * Request type specific data for unlink request:
     *         0                1                 2               3        octet
     * +----------------+----------------+----------------+----------------+
     * |           unlink_id             |                0                | 4
     * +----------------+----------------+----------------+----------------+
     * |                                 0                                 | 8
     * +----------------+----------------+----------------+----------------+
     *   unlink_id - uint16_t, request id of request to terminate
     *
     * seg[] array element layout:
     *         0                1                 2               3        octet
     * +----------------+----------------+----------------+----------------+
     * |                               gref                                | 4
     * +----------------+----------------+----------------+----------------+
     * |             offset              |             length              | 8
     * +----------------+----------------+----------------+----------------+
     *   gref - uint32_t, grant reference of buffer page
     *   offset - uint16_t, offset of buffer start in page
     *   length - uint16_t, length of buffer in page
     *
     *-------------------------- USB I/O response --------------------------------
     *
     *         0                1                 2               3        octet
     * +----------------+----------------+----------------+----------------+
     * |               id                |          start_frame            | 4
     * +----------------+----------------+----------------+----------------+
     * |                              status                               | 8
     * +----------------+----------------+----------------+----------------+
     * |                          actual_length                            | 12
     * +----------------+----------------+----------------+----------------+
     * |                           error_count                             | 16
     * +----------------+----------------+----------------+----------------+
     *   id - uint16_t, id of the request this response belongs to
     *   start_frame - uint16_t, start_frame this response (iso requests only)
     *   status - int32_t, USBIF_STATUS_* (non-iso requests)
     *   actual_length - uint32_t, actual size of data transferred
     *   error_count - uint32_t, number of errors (iso requests)
     */

    enum usb_spec_version {
        USB_VER_UNKNOWN = 0,
        USB_VER_USB11,
        USB_VER_USB20,
        USB_VER_USB30,    /* not supported yet */
    };

    /*
     *  USB pipe in usbif_request
     *
     *  - port number:      bits 0-4
     *                              (USB_MAXCHILDREN is 31)
     *
     *  - operation flag:   bit 5
     *                              (0 = submit urb,
     *                               1 = unlink urb)
     *
     *  - direction:        bit 7
     *                              (0 = Host-to-Device [Out]
     *                               1 = Device-to-Host [In])
     *
     *  - device address:   bits 8-14
     *
     *  - endpoint:         bits 15-18
     *
     *  - pipe type:        bits 30-31
     *                              (00 = isochronous, 01 = interrupt,
     *                               10 = control, 11 = bulk)
     */

    #define USBIF_PIPE_PORT_MASK    0x0000001f
    #define USBIF_PIPE_UNLINK       0x00000020
    #define USBIF_PIPE_DIR          0x00000080
    #define USBIF_PIPE_DEV_MASK     0x0000007f
    #define USBIF_PIPE_DEV_SHIFT    8
    #define USBIF_PIPE_EP_MASK      0x0000000f
    #define USBIF_PIPE_EP_SHIFT     15
    #define USBIF_PIPE_TYPE_MASK    0x00000003
    #define USBIF_PIPE_TYPE_SHIFT   30
    #define USBIF_PIPE_TYPE_ISOC    0
    #define USBIF_PIPE_TYPE_INT     1
    #define USBIF_PIPE_TYPE_CTRL    2
    #define USBIF_PIPE_TYPE_BULK    3

    #define usbif_pipeportnum(pipe)                 ((pipe) & USBIF_PIPE_PORT_MASK)
    #define usbif_setportnum_pipe(pipe, portnum)    ((pipe) | (portnum))

    #define usbif_pipeunlink(pipe)                  ((pipe) & USBIF_PIPE_UNLINK)
    #define usbif_pipesubmit(pipe)                  (!usbif_pipeunlink(pipe))
    #define usbif_setunlink_pipe(pipe)              ((pipe) | USBIF_PIPE_UNLINK)

    #define usbif_pipein(pipe)                      ((pipe) & USBIF_PIPE_DIR)
    #define usbif_pipeout(pipe)                     (!usbif_pipein(pipe))

    #define usbif_pipedevice(pipe)                  \
            (((pipe) >> USBIF_PIPE_DEV_SHIFT) & USBIF_PIPE_DEV_MASK)

    #define usbif_pipeendpoint(pipe)                \
            (((pipe) >> USBIF_PIPE_EP_SHIFT) & USBIF_PIPE_EP_MASK)

    #define usbif_pipetype(pipe)                    \
            (((pipe) >> USBIF_PIPE_TYPE_SHIFT) & USBIF_PIPE_TYPE_MASK)
    #define usbif_pipeisoc(pipe)    (usbif_pipetype(pipe) == USBIF_PIPE_TYPE_ISOC)
    #define usbif_pipeint(pipe)     (usbif_pipetype(pipe) == USBIF_PIPE_TYPE_INT)
    #define usbif_pipectrl(pipe)    (usbif_pipetype(pipe) == USBIF_PIPE_TYPE_CTRL)
    #define usbif_pipebulk(pipe)    (usbif_pipetype(pipe) == USBIF_PIPE_TYPE_BULK)

    #define USBIF_MAX_SEGMENTS_PER_REQUEST (16)
    #define USBIF_MAX_PORTNR        31
    #define USBIF_RING_SIZE         4096

    /*
     * RING for transferring urbs.
     */
    struct usbif_request_segment {
        grant_ref_t gref;
        uint16_t offset;
        uint16_t length;
    };

    struct usbif_urb_request {
        uint16_t id;                  /* request id */
        uint16_t nr_buffer_segs;      /* number of urb->transfer_buffer segments */

        /* basic urb parameter */
        uint32_t pipe;
        uint16_t transfer_flags;
    #define USBIF_SHORT_NOT_OK      0x0001
        uint16_t buffer_length;
        union {
            uint8_t ctrl[8];                 /* setup_packet (Ctrl) */

            struct {
                uint16_t interval;           /* maximum (1024*8) in usb core */
                uint16_t start_frame;        /* start frame */
                uint16_t number_of_packets;  /* number of ISO packet */
                uint16_t nr_frame_desc_segs; /* number of iso_frame_desc segments */
            } isoc;

            struct {
                uint16_t interval;           /* maximum (1024*8) in usb core */
                uint16_t pad[3];
            } intr;

            struct {
                uint16_t unlink_id;          /* unlink request id */
                uint16_t pad[3];
            } unlink;

        } u;

        /* urb data segments */
        struct usbif_request_segment seg[USBIF_MAX_SEGMENTS_PER_REQUEST];
    };
    typedef struct usbif_urb_request usbif_urb_request_t;

    struct usbif_urb_response {
        uint16_t id;           /* request id */
        uint16_t start_frame;  /* start frame (ISO) */
        int32_t status;        /* status (non-ISO) */
    #define USBIF_STATUS_OK         0
    #define USBIF_STATUS_NODEV      (-19)
    #define USBIF_STATUS_INVAL      (-22)
    #define USBIF_STATUS_STALL      (-32)
    #define USBIF_STATUS_IOERROR    (-71)
    #define USBIF_STATUS_BABBLE     (-75)
    #define USBIF_STATUS_SHUTDOWN   (-108)
        int32_t actual_length; /* actual transfer length */
        int32_t error_count;   /* number of ISO errors */
    };
    typedef struct usbif_urb_response usbif_urb_response_t;

    DEFINE_RING_TYPES(usbif_urb, struct usbif_urb_request, struct usbif_urb_response);
    #define USB_URB_RING_SIZE __CONST_RING_SIZE(usbif_urb, USBIF_RING_SIZE)

    /*
     * RING for notifying connect/disconnect events to frontend
     */
    struct usbif_conn_request {
        uint16_t id;
    };
    typedef struct usbif_conn_request usbif_conn_request_t;

    struct usbif_conn_response {
        uint16_t id;           /* request id */
        uint8_t portnum;       /* port number */
        uint8_t speed;         /* usb_device_speed */
    #define USBIF_SPEED_NONE        0
    #define USBIF_SPEED_LOW         1
    #define USBIF_SPEED_FULL        2
    #define USBIF_SPEED_HIGH        3
    };
    typedef struct usbif_conn_response usbif_conn_response_t;

    DEFINE_RING_TYPES(usbif_conn, struct usbif_conn_request, struct usbif_conn_response);
    #define USB_CONN_RING_SIZE __CONST_RING_SIZE(usbif_conn, USBIF_RING_SIZE)

    #endif /* __XEN_PUBLIC_IO_USBIF_H__ */