    /* SPDX-License-Identifier: MIT */
    /*
     * fbif.h -- Xen virtual frame buffer device
     *
     * Copyright (C) 2005 Anthony Liguori <aliguori@us.ibm.com>
     * Copyright (C) 2006 Red Hat, Inc., Markus Armbruster <armbru@redhat.com>
     */

    #ifndef __XEN_PUBLIC_IO_FBIF_H__
    #define __XEN_PUBLIC_IO_FBIF_H__

    /* Out events (frontend -> backend) */

    /*
     * Out events may be sent only when requested by backend, and receipt
     * of an unknown out event is an error.
     */

    /* Event type 1 currently not used */
    /*
     * Framebuffer update notification event
     * Capable frontend sets feature-update in xenstore.
     * Backend requests it by setting request-update in xenstore.
     */
    #define XENFB_TYPE_UPDATE 2

    struct xenfb_update
    {
        uint8_t type;    /* XENFB_TYPE_UPDATE */
        int32_t x;      /* source x */
        int32_t y;      /* source y */
        int32_t width;  /* rect width */
        int32_t height; /* rect height */
    };

    /*
     * Framebuffer resize notification event
     * Capable backend sets feature-resize in xenstore.
     */
    #define XENFB_TYPE_RESIZE 3

    struct xenfb_resize
    {
        uint8_t type;    /* XENFB_TYPE_RESIZE */
        int32_t width;   /* width in pixels */
        int32_t height;  /* height in pixels */
        int32_t stride;  /* stride in bytes */
        int32_t depth;   /* depth in bits */
        int32_t offset;  /* offset of the framebuffer in bytes */
    };

    #define XENFB_OUT_EVENT_SIZE 40

    union xenfb_out_event
    {
        uint8_t type;
        struct xenfb_update update;
        struct xenfb_resize resize;
        char pad[XENFB_OUT_EVENT_SIZE];
    };

    /* In events (backend -> frontend) */

    /*
     * Frontends should ignore unknown in events.
     */

    /*
     * Framebuffer refresh period advice
     * Backend sends it to advise the frontend their preferred period of
     * refresh.  Frontends that keep the framebuffer constantly up-to-date
     * just ignore it.  Frontends that use the advice should immediately
     * refresh the framebuffer (and send an update notification event if
     * those have been requested), then use the update frequency to guide
     * their periodical refreshs.
     */
    #define XENFB_TYPE_REFRESH_PERIOD 1
    #define XENFB_NO_REFRESH 0

    struct xenfb_refresh_period
    {
        uint8_t type;    /* XENFB_TYPE_UPDATE_PERIOD */
        uint32_t period; /* period of refresh, in ms,
                          * XENFB_NO_REFRESH if no refresh is needed */
    };

    #define XENFB_IN_EVENT_SIZE 40

    union xenfb_in_event
    {
        uint8_t type;
        struct xenfb_refresh_period refresh_period;
        char pad[XENFB_IN_EVENT_SIZE];
    };

    /* shared page */

    #define XENFB_IN_RING_SIZE 1024
    #define XENFB_IN_RING_LEN (XENFB_IN_RING_SIZE / XENFB_IN_EVENT_SIZE)
    #define XENFB_IN_RING_OFFS 1024
    #define XENFB_IN_RING(page) \
        ((union xenfb_in_event *)((char *)(page) + XENFB_IN_RING_OFFS))
    #define XENFB_IN_RING_REF(page, idx) \
        (XENFB_IN_RING((page))[(idx) % XENFB_IN_RING_LEN])

    #define XENFB_OUT_RING_SIZE 2048
    #define XENFB_OUT_RING_LEN (XENFB_OUT_RING_SIZE / XENFB_OUT_EVENT_SIZE)
    #define XENFB_OUT_RING_OFFS (XENFB_IN_RING_OFFS + XENFB_IN_RING_SIZE)
    #define XENFB_OUT_RING(page) \
        ((union xenfb_out_event *)((char *)(page) + XENFB_OUT_RING_OFFS))
    #define XENFB_OUT_RING_REF(page, idx) \
        (XENFB_OUT_RING((page))[(idx) % XENFB_OUT_RING_LEN])

    struct xenfb_page
    {
        uint32_t in_cons, in_prod;
        uint32_t out_cons, out_prod;

        int32_t width;          /* the width of the framebuffer (in pixels) */
        int32_t height;         /* the height of the framebuffer (in pixels) */
        uint32_t line_length;   /* the length of a row of pixels (in bytes) */
        uint32_t mem_length;    /* the length of the framebuffer (in bytes) */
        uint8_t depth;          /* the depth of a pixel (in bits) */

        /*
         * Framebuffer page directory
         *
         * Each directory page holds PAGE_SIZE / sizeof(*pd)
         * framebuffer pages, and can thus map up to PAGE_SIZE *
         * PAGE_SIZE / sizeof(*pd) bytes.  With PAGE_SIZE == 4096 and
         * sizeof(unsigned long) == 4/8, that's 4 Megs 32 bit and 2 Megs
         * 64 bit.  256 directories give enough room for a 512 Meg
         * framebuffer with a max resolution of 12,800x10,240.  Should
         * be enough for a while with room leftover for expansion.
         */
        unsigned long pd[256];
    };

    /*
     * Wart: xenkbd needs to know default resolution.  Put it here until a
     * better solution is found, but don't leak it to the backend.
     */
    #ifdef __KERNEL__
    #define XENFB_WIDTH 800
    #define XENFB_HEIGHT 600
    #define XENFB_DEPTH 32
    #endif

    #endif

    /*
     * Local variables:
     * mode: C
     * c-file-style: "BSD"
     * c-basic-offset: 4
     * tab-width: 4
     * indent-tabs-mode: nil
     * End:
     */