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@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
xen_drm_front_fb_to_cookie(struct drm_framebuffer * fb)134 static inline u64 xen_drm_front_fb_to_cookie(struct drm_framebuffer *fb)
135 {
136 return (uintptr_t)fb;
137 }
138
xen_drm_front_dbuf_to_cookie(struct drm_gem_object * gem_obj)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