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      1 /*	$NetBSD: xen_drm_front.h,v 1.2 2021/12/18 23:45:45 riastradh Exp $	*/
      2 
      3 /* SPDX-License-Identifier: GPL-2.0 OR MIT */
      4 
      5 /*
      6  *  Xen para-virtual DRM device
      7  *
      8  * Copyright (C) 2016-2018 EPAM Systems Inc.
      9  *
     10  * Author: Oleksandr Andrushchenko <oleksandr_andrushchenko (at) epam.com>
     11  */
     12 
     13 #ifndef __XEN_DRM_FRONT_H_
     14 #define __XEN_DRM_FRONT_H_
     15 
     16 #include <linux/scatterlist.h>
     17 
     18 #include <drm/drm_connector.h>
     19 #include <drm/drm_simple_kms_helper.h>
     20 
     21 #include "xen_drm_front_cfg.h"
     22 
     23 struct drm_device;
     24 struct drm_framebuffer;
     25 struct drm_gem_object;
     26 struct drm_pending_vblank_event;
     27 
     28 /**
     29  * DOC: Driver modes of operation in terms of display buffers used
     30  *
     31  * Depending on the requirements for the para-virtualized environment, namely
     32  * requirements dictated by the accompanying DRM/(v)GPU drivers running in both
     33  * host and guest environments, display buffers can be allocated by either
     34  * frontend driver or backend.
     35  */
     36 
     37 /**
     38  * DOC: Buffers allocated by the frontend driver
     39  *
     40  * In this mode of operation driver allocates buffers from system memory.
     41  *
     42  * Note! If used with accompanying DRM/(v)GPU drivers this mode of operation
     43  * may require IOMMU support on the platform, so accompanying DRM/vGPU
     44  * hardware can still reach display buffer memory while importing PRIME
     45  * buffers from the frontend driver.
     46  */
     47 
     48 /**
     49  * DOC: Buffers allocated by the backend
     50  *
     51  * This mode of operation is run-time configured via guest domain configuration
     52  * through XenStore entries.
     53  *
     54  * For systems which do not provide IOMMU support, but having specific
     55  * requirements for display buffers it is possible to allocate such buffers
     56  * at backend side and share those with the frontend.
     57  * For example, if host domain is 1:1 mapped and has DRM/GPU hardware expecting
     58  * physically contiguous memory, this allows implementing zero-copying
     59  * use-cases.
     60  *
     61  * Note, while using this scenario the following should be considered:
     62  *
     63  * #. If guest domain dies then pages/grants received from the backend
     64  *    cannot be claimed back
     65  *
     66  * #. Misbehaving guest may send too many requests to the
     67  *    backend exhausting its grant references and memory
     68  *    (consider this from security POV)
     69  */
     70 
     71 /**
     72  * DOC: Driver limitations
     73  *
     74  * #. Only primary plane without additional properties is supported.
     75  *
     76  * #. Only one video mode per connector supported which is configured
     77  *    via XenStore.
     78  *
     79  * #. All CRTCs operate at fixed frequency of 60Hz.
     80  */
     81 
     82 /* timeout in ms to wait for backend to respond */
     83 #define XEN_DRM_FRONT_WAIT_BACK_MS	3000
     84 
     85 #ifndef GRANT_INVALID_REF
     86 /*
     87  * Note on usage of grant reference 0 as invalid grant reference:
     88  * grant reference 0 is valid, but never exposed to a PV driver,
     89  * because of the fact it is already in use/reserved by the PV console.
     90  */
     91 #define GRANT_INVALID_REF	0
     92 #endif
     93 
     94 struct xen_drm_front_info {
     95 	struct xenbus_device *xb_dev;
     96 	struct xen_drm_front_drm_info *drm_info;
     97 
     98 	/* to protect data between backend IO code and interrupt handler */
     99 	spinlock_t io_lock;
    100 
    101 	int num_evt_pairs;
    102 	struct xen_drm_front_evtchnl_pair *evt_pairs;
    103 	struct xen_drm_front_cfg cfg;
    104 
    105 	/* display buffers */
    106 	struct list_head dbuf_list;
    107 };
    108 
    109 struct xen_drm_front_drm_pipeline {
    110 	struct xen_drm_front_drm_info *drm_info;
    111 
    112 	int index;
    113 
    114 	struct drm_simple_display_pipe pipe;
    115 
    116 	struct drm_connector conn;
    117 	/* These are only for connector mode checking */
    118 	int width, height;
    119 
    120 	struct drm_pending_vblank_event *pending_event;
    121 
    122 	struct delayed_work pflip_to_worker;
    123 
    124 	bool conn_connected;
    125 };
    126 
    127 struct xen_drm_front_drm_info {
    128 	struct xen_drm_front_info *front_info;
    129 	struct drm_device *drm_dev;
    130 
    131 	struct xen_drm_front_drm_pipeline pipeline[XEN_DRM_FRONT_MAX_CRTCS];
    132 };
    133 
    134 static inline u64 xen_drm_front_fb_to_cookie(struct drm_framebuffer *fb)
    135 {
    136 	return (uintptr_t)fb;
    137 }
    138 
    139 static inline u64 xen_drm_front_dbuf_to_cookie(struct drm_gem_object *gem_obj)
    140 {
    141 	return (uintptr_t)gem_obj;
    142 }
    143 
    144 int xen_drm_front_mode_set(struct xen_drm_front_drm_pipeline *pipeline,
    145 			   u32 x, u32 y, u32 width, u32 height,
    146 			   u32 bpp, u64 fb_cookie);
    147 
    148 int xen_drm_front_dbuf_create(struct xen_drm_front_info *front_info,
    149 			      u64 dbuf_cookie, u32 width, u32 height,
    150 			      u32 bpp, u64 size, struct page **pages);
    151 
    152 int xen_drm_front_fb_attach(struct xen_drm_front_info *front_info,
    153 			    u64 dbuf_cookie, u64 fb_cookie, u32 width,
    154 			    u32 height, u32 pixel_format);
    155 
    156 int xen_drm_front_fb_detach(struct xen_drm_front_info *front_info,
    157 			    u64 fb_cookie);
    158 
    159 int xen_drm_front_page_flip(struct xen_drm_front_info *front_info,
    160 			    int conn_idx, u64 fb_cookie);
    161 
    162 void xen_drm_front_on_frame_done(struct xen_drm_front_info *front_info,
    163 				 int conn_idx, u64 fb_cookie);
    164 
    165 #endif /* __XEN_DRM_FRONT_H_ */
    166