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+/******************************************************************************
+ * displif.h
+ *
+ * Unified display device I/O interface for Xen guest OSes.
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to
+ * deal in the Software without restriction, including without limitation the
+ * rights to use, copy, modify, merge, publish, distribute, sublicense, and/or
+ * sell copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
+ * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
+ * DEALINGS IN THE SOFTWARE.
+ *
+ * Copyright (C) 2016-2017 EPAM Systems Inc.
+ *
+ * Authors: Oleksandr Andrushchenko <oleksandr_andrushchenko@epam.com>
+ * Oleksandr Grytsov <oleksandr_grytsov@epam.com>
+ */
+
+#ifndef __XEN_PUBLIC_IO_DISPLIF_H__
+#define __XEN_PUBLIC_IO_DISPLIF_H__
+
+#include "ring.h"
+#include "../grant_table.h"
+
+/*
+ ******************************************************************************
+ * Protocol version
+ ******************************************************************************
+ */
+#define XENDISPL_PROTOCOL_VERSION "1"
+
+/*
+ ******************************************************************************
+ * Main features provided by the protocol
+ ******************************************************************************
+ * This protocol aims to provide a unified protocol which fits more
+ * sophisticated use-cases than a framebuffer device can handle. At the
+ * moment basic functionality is supported with the intention to be extended:
+ * o multiple dynamically allocated/destroyed framebuffers
+ * o buffers of arbitrary sizes
+ * o buffer allocation at either back or front end
+ * o better configuration options including multiple display support
+ *
+ * Note: existing fbif can be used together with displif running at the
+ * same time, e.g. on Linux one provides framebuffer and another DRM/KMS
+ *
+ * Note: display resolution (XenStore's "resolution" property) defines
+ * visible area of the virtual display. At the same time resolution of
+ * the display and frame buffers may differ: buffers can be smaller, equal
+ * or bigger than the visible area. This is to enable use-cases, where backend
+ * may do some post-processing of the display and frame buffers supplied,
+ * e.g. those buffers can be just a part of the final composition.
+ *
+ ******************************************************************************
+ * Direction of improvements
+ ******************************************************************************
+ * Future extensions to the existing protocol may include:
+ * o display/connector cloning
+ * o allocation of objects other than display buffers
+ * o plane/overlay support
+ * o scaling support
+ * o rotation support
+ *
+ ******************************************************************************
+ * Feature and Parameter Negotiation
+ ******************************************************************************
+ *
+ * Front->back notifications: when enqueuing a new request, sending a
+ * notification can be made conditional on xendispl_req (i.e., the generic
+ * hold-off mechanism provided by the ring macros). Backends must set
+ * xendispl_req appropriately (e.g., using RING_FINAL_CHECK_FOR_REQUESTS()).
+ *
+ * Back->front notifications: when enqueuing a new response, sending a
+ * notification can be made conditional on xendispl_resp (i.e., the generic
+ * hold-off mechanism provided by the ring macros). Frontends must set
+ * xendispl_resp appropriately (e.g., using RING_FINAL_CHECK_FOR_RESPONSES()).
+ *
+ * The two halves of a para-virtual display driver utilize nodes within
+ * XenStore to communicate capabilities and to negotiate operating parameters.
+ * This section enumerates these nodes which reside in the respective front and
+ * backend portions of XenStore, following the XenBus convention.
+ *
+ * All data in XenStore is stored as strings. Nodes specifying numeric
+ * values are encoded in decimal. Integer value ranges listed below are
+ * expressed as fixed sized integer types capable of storing the conversion
+ * of a properly formated node string, without loss of information.
+ *
+ ******************************************************************************
+ * Example configuration
+ ******************************************************************************
+ *
+ * Note: depending on the use-case backend can expose more display connectors
+ * than the underlying HW physically has by employing SW graphics compositors
+ *
+ * This is an example of backend and frontend configuration:
+ *
+ *--------------------------------- Backend -----------------------------------
+ *
+ * /local/domain/0/backend/vdispl/1/0/frontend-id = "1"
+ * /local/domain/0/backend/vdispl/1/0/frontend = "/local/domain/1/device/vdispl/0"
+ * /local/domain/0/backend/vdispl/1/0/state = "4"
+ * /local/domain/0/backend/vdispl/1/0/versions = "1,2"
+ *
+ *--------------------------------- Frontend ----------------------------------
+ *
+ * /local/domain/1/device/vdispl/0/backend-id = "0"
+ * /local/domain/1/device/vdispl/0/backend = "/local/domain/0/backend/vdispl/1/0"
+ * /local/domain/1/device/vdispl/0/state = "4"
+ * /local/domain/1/device/vdispl/0/version = "1"
+ * /local/domain/1/device/vdispl/0/be-alloc = "1"
+ *
+ *-------------------------- Connector 0 configuration ------------------------
+ *
+ * /local/domain/1/device/vdispl/0/0/resolution = "1920x1080"
+ * /local/domain/1/device/vdispl/0/0/req-ring-ref = "2832"
+ * /local/domain/1/device/vdispl/0/0/req-event-channel = "15"
+ * /local/domain/1/device/vdispl/0/0/evt-ring-ref = "387"
+ * /local/domain/1/device/vdispl/0/0/evt-event-channel = "16"
+ *
+ *-------------------------- Connector 1 configuration ------------------------
+ *
+ * /local/domain/1/device/vdispl/0/1/resolution = "800x600"
+ * /local/domain/1/device/vdispl/0/1/req-ring-ref = "2833"
+ * /local/domain/1/device/vdispl/0/1/req-event-channel = "17"
+ * /local/domain/1/device/vdispl/0/1/evt-ring-ref = "388"
+ * /local/domain/1/device/vdispl/0/1/evt-event-channel = "18"
+ *
+ ******************************************************************************
+ * Backend XenBus Nodes
+ ******************************************************************************
+ *
+ *----------------------------- Protocol version ------------------------------
+ *
+ * versions
+ * Values: <string>
+ *
+ * List of XENDISPL_LIST_SEPARATOR separated protocol versions supported
+ * by the backend. For example "1,2,3".
+ *
+ ******************************************************************************
+ * Frontend XenBus Nodes
+ ******************************************************************************
+ *
+ *-------------------------------- Addressing ---------------------------------
+ *
+ * dom-id
+ * Values: <uint16_t>
+ *
+ * Domain identifier.
+ *
+ * dev-id
+ * Values: <uint16_t>
+ *
+ * Device identifier.
+ *
+ * conn-idx
+ * Values: <uint8_t>
+ *
+ * Zero based contigous index of the connector.
+ * /local/domain/<dom-id>/device/vdispl/<dev-id>/<conn-idx>/...
+ *
+ *----------------------------- Protocol version ------------------------------
+ *
+ * version
+ * Values: <string>
+ *
+ * Protocol version, chosen among the ones supported by the backend.
+ *
+ *------------------------- Backend buffer allocation -------------------------
+ *
+ * be-alloc
+ * Values: "0", "1"
+ *
+ * If value is set to "1", then backend can be a buffer provider/allocator
+ * for this domain during XENDISPL_OP_DBUF_CREATE operation (see below
+ * for negotiation).
+ * If value is not "1" or omitted frontend must allocate buffers itself.
+ *
+ *----------------------------- Connector settings ----------------------------
+ *
+ * resolution
+ * Values: <width, uint32_t>x<height, uint32_t>
+ *
+ * Width and height of the connector in pixels separated by
+ * XENDISPL_RESOLUTION_SEPARATOR. This defines visible area of the
+ * display.
+ *
+ *------------------ Connector Request Transport Parameters -------------------
+ *
+ * This communication path is used to deliver requests from frontend to backend
+ * and get the corresponding responses from backend to frontend,
+ * set up per connector.
+ *
+ * req-event-channel
+ * Values: <uint32_t>
+ *
+ * The identifier of the Xen connector's control event channel
+ * used to signal activity in the ring buffer.
+ *
+ * req-ring-ref
+ * Values: <uint32_t>
+ *
+ * The Xen grant reference granting permission for the backend to map
+ * a sole page of connector's control ring buffer.
+ *
+ *------------------- Connector Event Transport Parameters --------------------
+ *
+ * This communication path is used to deliver asynchronous events from backend
+ * to frontend, set up per connector.
+ *
+ * evt-event-channel
+ * Values: <uint32_t>
+ *
+ * The identifier of the Xen connector's event channel
+ * used to signal activity in the ring buffer.
+ *
+ * evt-ring-ref
+ * Values: <uint32_t>
+ *
+ * The Xen grant reference granting permission for the backend to map
+ * a sole page of connector's event ring buffer.
+ */
+
+/*
+ ******************************************************************************
+ * STATE DIAGRAMS
+ ******************************************************************************
+ *
+ * Tool stack creates front and back state nodes with initial state
+ * XenbusStateInitialising.
+ * Tool stack creates and sets up frontend display configuration
+ * nodes per domain.
+ *
+ *-------------------------------- Normal flow --------------------------------
+ *
+ * Front Back
+ * ================================= =====================================
+ * XenbusStateInitialising XenbusStateInitialising
+ * o Query backend device identification
+ * data.
+ * o Open and validate backend device.
+ * |
+ * |
+ * V
+ * XenbusStateInitWait
+ *
+ * o Query frontend configuration
+ * o Allocate and initialize
+ * event channels per configured
+ * connector.
+ * o Publish transport parameters
+ * that will be in effect during
+ * this connection.
+ * |
+ * |
+ * V
+ * XenbusStateInitialised
+ *
+ * o Query frontend transport parameters.
+ * o Connect to the event channels.
+ * |
+ * |
+ * V
+ * XenbusStateConnected
+ *
+ * o Create and initialize OS
+ * virtual display connectors
+ * as per configuration.
+ * |
+ * |
+ * V
+ * XenbusStateConnected
+ *
+ * XenbusStateUnknown
+ * XenbusStateClosed
+ * XenbusStateClosing
+ * o Remove virtual display device
+ * o Remove event channels
+ * |
+ * |
+ * V
+ * XenbusStateClosed
+ *
+ *------------------------------- Recovery flow -------------------------------
+ *
+ * In case of frontend unrecoverable errors backend handles that as
+ * if frontend goes into the XenbusStateClosed state.
+ *
+ * In case of backend unrecoverable errors frontend tries removing
+ * the virtualized device. If this is possible at the moment of error,
+ * then frontend goes into the XenbusStateInitialising state and is ready for
+ * new connection with backend. If the virtualized device is still in use and
+ * cannot be removed, then frontend goes into the XenbusStateReconfiguring state
+ * until either the virtualized device is removed or backend initiates a new
+ * connection. On the virtualized device removal frontend goes into the
+ * XenbusStateInitialising state.
+ *
+ * Note on XenbusStateReconfiguring state of the frontend: if backend has
+ * unrecoverable errors then frontend cannot send requests to the backend
+ * and thus cannot provide functionality of the virtualized device anymore.
+ * After backend is back to normal the virtualized device may still hold some
+ * state: configuration in use, allocated buffers, client application state etc.
+ * In most cases, this will require frontend to implement complex recovery
+ * reconnect logic. Instead, by going into XenbusStateReconfiguring state,
+ * frontend will make sure no new clients of the virtualized device are
+ * accepted, allow existing client(s) to exit gracefully by signaling error
+ * state etc.
+ * Once all the clients are gone frontend can reinitialize the virtualized
+ * device and get into XenbusStateInitialising state again signaling the
+ * backend that a new connection can be made.
+ *
+ * There are multiple conditions possible under which frontend will go from
+ * XenbusStateReconfiguring into XenbusStateInitialising, some of them are OS
+ * specific. For example:
+ * 1. The underlying OS framework may provide callbacks to signal that the last
+ * client of the virtualized device has gone and the device can be removed
+ * 2. Frontend can schedule a deferred work (timer/tasklet/workqueue)
+ * to periodically check if this is the right time to re-try removal of
+ * the virtualized device.
+ * 3. By any other means.
+ *
+ ******************************************************************************
+ * REQUEST CODES
+ ******************************************************************************
+ * Request codes [0; 15] are reserved and must not be used
+ */
+
+#define XENDISPL_OP_DBUF_CREATE 0x10
+#define XENDISPL_OP_DBUF_DESTROY 0x11
+#define XENDISPL_OP_FB_ATTACH 0x12
+#define XENDISPL_OP_FB_DETACH 0x13
+#define XENDISPL_OP_SET_CONFIG 0x14
+#define XENDISPL_OP_PG_FLIP 0x15
+
+/*
+ ******************************************************************************
+ * EVENT CODES
+ ******************************************************************************
+ */
+#define XENDISPL_EVT_PG_FLIP 0x00
+
+/*
+ ******************************************************************************
+ * XENSTORE FIELD AND PATH NAME STRINGS, HELPERS
+ ******************************************************************************
+ */
+#define XENDISPL_DRIVER_NAME "vdispl"
+
+#define XENDISPL_LIST_SEPARATOR ","
+#define XENDISPL_RESOLUTION_SEPARATOR "x"
+
+#define XENDISPL_FIELD_BE_VERSIONS "versions"
+#define XENDISPL_FIELD_FE_VERSION "version"
+#define XENDISPL_FIELD_REQ_RING_REF "req-ring-ref"
+#define XENDISPL_FIELD_REQ_CHANNEL "req-event-channel"
+#define XENDISPL_FIELD_EVT_RING_REF "evt-ring-ref"
+#define XENDISPL_FIELD_EVT_CHANNEL "evt-event-channel"
+#define XENDISPL_FIELD_RESOLUTION "resolution"
+#define XENDISPL_FIELD_BE_ALLOC "be-alloc"
+
+/*
+ ******************************************************************************
+ * STATUS RETURN CODES
+ ******************************************************************************
+ *
+ * Status return code is zero on success and -XEN_EXX on failure.
+ *
+ ******************************************************************************
+ * Assumptions
+ ******************************************************************************
+ * o usage of grant reference 0 as invalid grant reference:
+ * grant reference 0 is valid, but never exposed to a PV driver,
+ * because of the fact it is already in use/reserved by the PV console.
+ * o all references in this document to page sizes must be treated
+ * as pages of size XEN_PAGE_SIZE unless otherwise noted.
+ *
+ ******************************************************************************
+ * Description of the protocol between frontend and backend driver
+ ******************************************************************************
+ *
+ * The two halves of a Para-virtual display driver communicate with
+ * each other using shared pages and event channels.
+ * Shared page contains a ring with request/response packets.
+ *
+ * All reserved fields in the structures below must be 0.
+ * Display buffers's cookie of value 0 is treated as invalid.
+ * Framebuffer's cookie of value 0 is treated as invalid.
+ *
+ * For all request/response/event packets that use cookies:
+ * dbuf_cookie - uint64_t, unique to guest domain value used by the backend
+ * to map remote display buffer to its local one
+ * fb_cookie - uint64_t, unique to guest domain value used by the backend
+ * to map remote framebuffer to its local one
+ *
+ *---------------------------------- Requests ---------------------------------
+ *
+ * All requests/responses, which are not connector specific, must be sent over
+ * control ring of the connector which has the index value of 0:
+ * /local/domain/<dom-id>/device/vdispl/<dev-id>/0/req-ring-ref
+ *
+ * All request packets have the same length (64 octets)
+ * All request packets have common header:
+ * 0 1 2 3 octet
+ * +----------------+----------------+----------------+----------------+
+ * | id | operation | reserved | 4
+ * +----------------+----------------+----------------+----------------+
+ * | reserved | 8
+ * +----------------+----------------+----------------+----------------+
+ * id - uint16_t, private guest value, echoed in response
+ * operation - uint8_t, operation code, XENDISPL_OP_???
+ *
+ * Request dbuf creation - request creation of a display buffer.
+ * 0 1 2 3 octet
+ * +----------------+----------------+----------------+----------------+
+ * | id |_OP_DBUF_CREATE | reserved | 4
+ * +----------------+----------------+----------------+----------------+
+ * | reserved | 8
+ * +----------------+----------------+----------------+----------------+
+ * | dbuf_cookie low 32-bit | 12
+ * +----------------+----------------+----------------+----------------+
+ * | dbuf_cookie high 32-bit | 16
+ * +----------------+----------------+----------------+----------------+
+ * | width | 20
+ * +----------------+----------------+----------------+----------------+
+ * | height | 24
+ * +----------------+----------------+----------------+----------------+
+ * | bpp | 28
+ * +----------------+----------------+----------------+----------------+
+ * | buffer_sz | 32
+ * +----------------+----------------+----------------+----------------+
+ * | flags | 36
+ * +----------------+----------------+----------------+----------------+
+ * | gref_directory | 40
+ * +----------------+----------------+----------------+----------------+
+ * | reserved | 44
+ * +----------------+----------------+----------------+----------------+
+ * |/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/|
+ * +----------------+----------------+----------------+----------------+
+ * | reserved | 64
+ * +----------------+----------------+----------------+----------------+
+ *
+ * Must be sent over control ring of the connector which has the index
+ * value of 0:
+ * /local/domain/<dom-id>/device/vdispl/<dev-id>/0/req-ring-ref
+ * All unused bits in flags field must be set to 0.
+ *
+ * An attempt to create multiple display buffers with the same dbuf_cookie is
+ * an error. dbuf_cookie can be re-used after destroying the corresponding
+ * display buffer.
+ *
+ * Width and height of the display buffers can be smaller, equal or bigger
+ * than the connector's resolution. Depth/pixel format of the individual
+ * buffers can differ as well.
+ *
+ * width - uint32_t, width in pixels
+ * height - uint32_t, height in pixels
+ * bpp - uint32_t, bits per pixel
+ * buffer_sz - uint32_t, buffer size to be allocated, octets
+ * flags - uint32_t, flags of the operation
+ * o XENDISPL_DBUF_FLG_REQ_ALLOC - if set, then backend is requested
+ * to allocate the buffer with the parameters provided in this request.
+ * Page directory is handled as follows:
+ * Frontend on request:
+ * o allocates pages for the directory (gref_directory,
+ * gref_dir_next_page(s)
+ * o grants permissions for the pages of the directory to the backend
+ * o sets gref_dir_next_page fields
+ * Backend on response:
+ * o grants permissions for the pages of the buffer allocated to
+ * the frontend
+ * o fills in page directory with grant references
+ * (gref[] in struct xendispl_page_directory)
+ * gref_directory - grant_ref_t, a reference to the first shared page
+ * describing shared buffer references. At least one page exists. If shared
+ * buffer size (buffer_sz) exceeds what can be addressed by this single page,
+ * then reference to the next page must be supplied (see gref_dir_next_page
+ * below)
+ */
+
+#define XENDISPL_DBUF_FLG_REQ_ALLOC (1 << 0)
+
+struct xendispl_dbuf_create_req {
+ uint64_t dbuf_cookie;
+ uint32_t width;
+ uint32_t height;
+ uint32_t bpp;
+ uint32_t buffer_sz;
+ uint32_t flags;
+ grant_ref_t gref_directory;
+};
+
+/*
+ * Shared page for XENDISPL_OP_DBUF_CREATE buffer descriptor (gref_directory in
+ * the request) employs a list of pages, describing all pages of the shared
+ * data buffer:
+ * 0 1 2 3 octet
+ * +----------------+----------------+----------------+----------------+
+ * | gref_dir_next_page | 4
+ * +----------------+----------------+----------------+----------------+
+ * | gref[0] | 8
+ * +----------------+----------------+----------------+----------------+
+ * |/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/|
+ * +----------------+----------------+----------------+----------------+
+ * | gref[i] | i*4+8
+ * +----------------+----------------+----------------+----------------+
+ * |/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/|
+ * +----------------+----------------+----------------+----------------+
+ * | gref[N - 1] | N*4+8
+ * +----------------+----------------+----------------+----------------+
+ *
+ * gref_dir_next_page - grant_ref_t, reference to the next page describing
+ * page directory. Must be 0 if there are no more pages in the list.
+ * gref[i] - grant_ref_t, reference to a shared page of the buffer
+ * allocated at XENDISPL_OP_DBUF_CREATE
+ *
+ * Number of grant_ref_t entries in the whole page directory is not
+ * passed, but instead can be calculated as:
+ * num_grefs_total = (XENDISPL_OP_DBUF_CREATE.buffer_sz + XEN_PAGE_SIZE - 1) /
+ * XEN_PAGE_SIZE
+ */
+
+struct xendispl_page_directory {
+ grant_ref_t gref_dir_next_page;
+ grant_ref_t gref[1]; /* Variable length */
+};
+
+/*
+ * Request dbuf destruction - destroy a previously allocated display buffer:
+ * 0 1 2 3 octet
+ * +----------------+----------------+----------------+----------------+
+ * | id |_OP_DBUF_DESTROY| reserved | 4
+ * +----------------+----------------+----------------+----------------+
+ * | reserved | 8
+ * +----------------+----------------+----------------+----------------+
+ * | dbuf_cookie low 32-bit | 12
+ * +----------------+----------------+----------------+----------------+
+ * | dbuf_cookie high 32-bit | 16
+ * +----------------+----------------+----------------+----------------+
+ * | reserved | 20
+ * +----------------+----------------+----------------+----------------+
+ * |/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/|
+ * +----------------+----------------+----------------+----------------+
+ * | reserved | 64
+ * +----------------+----------------+----------------+----------------+
+ *
+ * Must be sent over control ring of the connector which has the index
+ * value of 0:
+ * /local/domain/<dom-id>/device/vdispl/<dev-id>/0/req-ring-ref
+ */
+
+struct xendispl_dbuf_destroy_req {
+ uint64_t dbuf_cookie;
+};
+
+/*
+ * Request framebuffer attachment - request attachment of a framebuffer to
+ * previously created display buffer.
+ * 0 1 2 3 octet
+ * +----------------+----------------+----------------+----------------+
+ * | id | _OP_FB_ATTACH | reserved | 4
+ * +----------------+----------------+----------------+----------------+
+ * | reserved | 8
+ * +----------------+----------------+----------------+----------------+
+ * | dbuf_cookie low 32-bit | 12
+ * +----------------+----------------+----------------+----------------+
+ * | dbuf_cookie high 32-bit | 16
+ * +----------------+----------------+----------------+----------------+
+ * | fb_cookie low 32-bit | 20
+ * +----------------+----------------+----------------+----------------+
+ * | fb_cookie high 32-bit | 24
+ * +----------------+----------------+----------------+----------------+
+ * | width | 28
+ * +----------------+----------------+----------------+----------------+
+ * | height | 32
+ * +----------------+----------------+----------------+----------------+
+ * | pixel_format | 36
+ * +----------------+----------------+----------------+----------------+
+ * | reserved | 40
+ * +----------------+----------------+----------------+----------------+
+ * |/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/|
+ * +----------------+----------------+----------------+----------------+
+ * | reserved | 64
+ * +----------------+----------------+----------------+----------------+
+ *
+ * Must be sent over control ring of the connector which has the index
+ * value of 0:
+ * /local/domain/<dom-id>/device/vdispl/<dev-id>/0/req-ring-ref
+ * Width and height can be smaller, equal or bigger than the connector's
+ * resolution.
+ *
+ * An attempt to create multiple frame buffers with the same fb_cookie is
+ * an error. fb_cookie can be re-used after destroying the corresponding
+ * frame buffer.
+ *
+ * width - uint32_t, width in pixels
+ * height - uint32_t, height in pixels
+ * pixel_format - uint32_t, pixel format of the framebuffer, FOURCC code
+ */
+
+struct xendispl_fb_attach_req {
+ uint64_t dbuf_cookie;
+ uint64_t fb_cookie;
+ uint32_t width;
+ uint32_t height;
+ uint32_t pixel_format;
+};
+
+/*
+ * Request framebuffer detach - detach a previously
+ * attached framebuffer from the display buffer in request:
+ * 0 1 2 3 octet
+ * +----------------+----------------+----------------+----------------+
+ * | id | _OP_FB_DETACH | reserved | 4
+ * +----------------+----------------+----------------+----------------+
+ * | reserved | 8
+ * +----------------+----------------+----------------+----------------+
+ * | fb_cookie low 32-bit | 12
+ * +----------------+----------------+----------------+----------------+
+ * | fb_cookie high 32-bit | 16
+ * +----------------+----------------+----------------+----------------+
+ * | reserved | 20
+ * +----------------+----------------+----------------+----------------+
+ * |/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/|
+ * +----------------+----------------+----------------+----------------+
+ * | reserved | 64
+ * +----------------+----------------+----------------+----------------+
+ *
+ * Must be sent over control ring of the connector which has the index
+ * value of 0:
+ * /local/domain/<dom-id>/device/vdispl/<dev-id>/0/req-ring-ref
+ */
+
+struct xendispl_fb_detach_req {
+ uint64_t fb_cookie;
+};
+
+/*
+ * Request configuration set/reset - request to set or reset
+ * the configuration/mode of the display:
+ * 0 1 2 3 octet
+ * +----------------+----------------+----------------+----------------+
+ * | id | _OP_SET_CONFIG | reserved | 4
+ * +----------------+----------------+----------------+----------------+
+ * | reserved | 8
+ * +----------------+----------------+----------------+----------------+
+ * | fb_cookie low 32-bit | 12
+ * +----------------+----------------+----------------+----------------+
+ * | fb_cookie high 32-bit | 16
+ * +----------------+----------------+----------------+----------------+
+ * | x | 20
+ * +----------------+----------------+----------------+----------------+
+ * | y | 24
+ * +----------------+----------------+----------------+----------------+
+ * | width | 28
+ * +----------------+----------------+----------------+----------------+
+ * | height | 32
+ * +----------------+----------------+----------------+----------------+
+ * | bpp | 40
+ * +----------------+----------------+----------------+----------------+
+ * | reserved | 44
+ * +----------------+----------------+----------------+----------------+
+ * |/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/|
+ * +----------------+----------------+----------------+----------------+
+ * | reserved | 64
+ * +----------------+----------------+----------------+----------------+
+ *
+ * Pass all zeros to reset, otherwise command is treated as
+ * configuration set.
+ * Framebuffer's cookie defines which framebuffer/dbuf must be
+ * displayed while enabling display (applying configuration).
+ * x, y, width and height are bound by the connector's resolution and must not
+ * exceed it.
+ *
+ * x - uint32_t, starting position in pixels by X axis
+ * y - uint32_t, starting position in pixels by Y axis
+ * width - uint32_t, width in pixels
+ * height - uint32_t, height in pixels
+ * bpp - uint32_t, bits per pixel
+ */
+
+struct xendispl_set_config_req {
+ uint64_t fb_cookie;
+ uint32_t x;
+ uint32_t y;
+ uint32_t width;
+ uint32_t height;
+ uint32_t bpp;
+};
+
+/*
+ * Request page flip - request to flip a page identified by the framebuffer
+ * cookie:
+ * 0 1 2 3 octet
+ * +----------------+----------------+----------------+----------------+
+ * | id | _OP_PG_FLIP | reserved | 4
+ * +----------------+----------------+----------------+----------------+
+ * | reserved | 8
+ * +----------------+----------------+----------------+----------------+
+ * | fb_cookie low 32-bit | 12
+ * +----------------+----------------+----------------+----------------+
+ * | fb_cookie high 32-bit | 16
+ * +----------------+----------------+----------------+----------------+
+ * | reserved | 20
+ * +----------------+----------------+----------------+----------------+
+ * |/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/|
+ * +----------------+----------------+----------------+----------------+
+ * | reserved | 64
+ * +----------------+----------------+----------------+----------------+
+ */
+
+struct xendispl_page_flip_req {
+ uint64_t fb_cookie;
+};
+
+/*
+ *---------------------------------- Responses --------------------------------
+ *
+ * All response packets have the same length (64 octets)
+ *
+ * All response packets have common header:
+ * 0 1 2 3 octet
+ * +----------------+----------------+----------------+----------------+
+ * | id | reserved | 4
+ * +----------------+----------------+----------------+----------------+
+ * | status | 8
+ * +----------------+----------------+----------------+----------------+
+ * | reserved | 12
+ * +----------------+----------------+----------------+----------------+
+ * |/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/|
+ * +----------------+----------------+----------------+----------------+
+ * | reserved | 64
+ * +----------------+----------------+----------------+----------------+
+ *
+ * id - uint16_t, private guest value, echoed from request
+ * status - int32_t, response status, zero on success and -XEN_EXX on failure
+ *
+ *----------------------------------- Events ----------------------------------
+ *
+ * Events are sent via a shared page allocated by the front and propagated by
+ * evt-event-channel/evt-ring-ref XenStore entries
+ * All event packets have the same length (64 octets)
+ * All event packets have common header:
+ * 0 1 2 3 octet
+ * +----------------+----------------+----------------+----------------+
+ * | id | type | reserved | 4
+ * +----------------+----------------+----------------+----------------+
+ * | reserved | 8
+ * +----------------+----------------+----------------+----------------+
+ *
+ * id - uint16_t, event id, may be used by front
+ * type - uint8_t, type of the event
+ *
+ *
+ * Page flip complete event - event from back to front on page flip completed:
+ * 0 1 2 3 octet
+ * +----------------+----------------+----------------+----------------+
+ * | id | _EVT_PG_FLIP | reserved | 4
+ * +----------------+----------------+----------------+----------------+
+ * | reserved | 8
+ * +----------------+----------------+----------------+----------------+
+ * | fb_cookie low 32-bit | 12
+ * +----------------+----------------+----------------+----------------+
+ * | fb_cookie high 32-bit | 16
+ * +----------------+----------------+----------------+----------------+
+ * | reserved | 20
+ * +----------------+----------------+----------------+----------------+
+ * |/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/|
+ * +----------------+----------------+----------------+----------------+
+ * | reserved | 64
+ * +----------------+----------------+----------------+----------------+
+ */
+
+struct xendispl_pg_flip_evt {
+ uint64_t fb_cookie;
+};
+
+struct xendispl_req {
+ uint16_t id;
+ uint8_t operation;
+ uint8_t reserved[5];
+ union {
+ struct xendispl_dbuf_create_req dbuf_create;
+ struct xendispl_dbuf_destroy_req dbuf_destroy;
+ struct xendispl_fb_attach_req fb_attach;
+ struct xendispl_fb_detach_req fb_detach;
+ struct xendispl_set_config_req set_config;
+ struct xendispl_page_flip_req pg_flip;
+ uint8_t reserved[56];
+ } op;
+};
+
+struct xendispl_resp {
+ uint16_t id;
+ uint8_t operation;
+ uint8_t reserved;
+ int32_t status;
+ uint8_t reserved1[56];
+};
+
+struct xendispl_evt {
+ uint16_t id;
+ uint8_t type;
+ uint8_t reserved[5];
+ union {
+ struct xendispl_pg_flip_evt pg_flip;
+ uint8_t reserved[56];
+ } op;
+};
+
+DEFINE_RING_TYPES(xen_displif, struct xendispl_req, struct xendispl_resp);
+
+/*
+ ******************************************************************************
+ * Back to front events delivery
+ ******************************************************************************
+ * In order to deliver asynchronous events from back to front a shared page is
+ * allocated by front and its granted reference propagated to back via
+ * XenStore entries (evt-ring-ref/evt-event-channel).
+ * This page has a common header used by both front and back to synchronize
+ * access and control event's ring buffer, while back being a producer of the
+ * events and front being a consumer. The rest of the page after the header
+ * is used for event packets.
+ *
+ * Upon reception of an event(s) front may confirm its reception
+ * for either each event, group of events or none.
+ */
+
+struct xendispl_event_page {
+ uint32_t in_cons;
+ uint32_t in_prod;
+ uint8_t reserved[56];
+};
+
+#define XENDISPL_EVENT_PAGE_SIZE XEN_PAGE_SIZE
+#define XENDISPL_IN_RING_OFFS (sizeof(struct xendispl_event_page))
+#define XENDISPL_IN_RING_SIZE (XENDISPL_EVENT_PAGE_SIZE - XENDISPL_IN_RING_OFFS)
+#define XENDISPL_IN_RING_LEN (XENDISPL_IN_RING_SIZE / sizeof(struct xendispl_evt))
+#define XENDISPL_IN_RING(page) \
+ ((struct xendispl_evt *)((char *)(page) + XENDISPL_IN_RING_OFFS))
+#define XENDISPL_IN_RING_REF(page, idx) \
+ (XENDISPL_IN_RING((page))[(idx) % XENDISPL_IN_RING_LEN])
+
+#endif /* __XEN_PUBLIC_IO_DISPLIF_H__ */
Copyright © 1996 – 2023 Jason A. Donenfeld. All Rights Reverse Engineered.