/*	$NetBSD: xen_drm_front_evtchnl.h,v 1.2 2021/12/18 23:45:45 riastradh Exp $	*/

/* SPDX-License-Identifier: GPL-2.0 OR MIT */

/*
 *  Xen para-virtual DRM device
 *
 * Copyright (C) 2016-2018 EPAM Systems Inc.
 *
 * Author: Oleksandr Andrushchenko <oleksandr_andrushchenko@epam.com>
 */

#ifndef __XEN_DRM_FRONT_EVTCHNL_H_
#define __XEN_DRM_FRONT_EVTCHNL_H_

#include <linux/completion.h>
#include <linux/types.h>

#include <xen/interface/io/ring.h>
#include <xen/interface/io/displif.h>

/*
 * All operations which are not connector oriented use this ctrl event channel,
 * e.g. fb_attach/destroy which belong to a DRM device, not to a CRTC.
 */
#define GENERIC_OP_EVT_CHNL	0

enum xen_drm_front_evtchnl_state {
	EVTCHNL_STATE_DISCONNECTED,
	EVTCHNL_STATE_CONNECTED,
};

enum xen_drm_front_evtchnl_type {
	EVTCHNL_TYPE_REQ,
	EVTCHNL_TYPE_EVT,
};

struct xen_drm_front_drm_info;

struct xen_drm_front_evtchnl {
	struct xen_drm_front_info *front_info;
	int gref;
	int port;
	int irq;
	int index;
	enum xen_drm_front_evtchnl_state state;
	enum xen_drm_front_evtchnl_type type;
	/* either response id or incoming event id */
	u16 evt_id;
	/* next request id or next expected event id */
	u16 evt_next_id;
	union {
		struct {
			struct xen_displif_front_ring ring;
			struct completion completion;
			/* latest response status */
			int resp_status;
			/* serializer for backend IO: request/response */
			struct mutex req_io_lock;
		} req;
		struct {
			struct xendispl_event_page *page;
		} evt;
	} u;
};

struct xen_drm_front_evtchnl_pair {
	struct xen_drm_front_evtchnl req;
	struct xen_drm_front_evtchnl evt;
};

int xen_drm_front_evtchnl_create_all(struct xen_drm_front_info *front_info);

int xen_drm_front_evtchnl_publish_all(struct xen_drm_front_info *front_info);

void xen_drm_front_evtchnl_flush(struct xen_drm_front_evtchnl *evtchnl);

void xen_drm_front_evtchnl_set_state(struct xen_drm_front_info *front_info,
				     enum xen_drm_front_evtchnl_state state);

void xen_drm_front_evtchnl_free_all(struct xen_drm_front_info *front_info);

#endif /* __XEN_DRM_FRONT_EVTCHNL_H_ */