drm/xen/xen_drm_front.h

0001 /* SPDX-License-Identifier: GPL-2.0 OR MIT */
0002
0003 /*
0004  *  Xen para-virtual DRM device
0005  *
0006  * Copyright (C) 2016-2018 EPAM Systems Inc.
0007  *
0008  * Author: Oleksandr Andrushchenko <oleksandr_andrushchenko@epam.com>
0009  */
0010
0011 #ifndef __XEN_DRM_FRONT_H_
0012 #define __XEN_DRM_FRONT_H_
0013
0014 #include <linux/scatterlist.h>
0015
0016 #include <drm/drm_connector.h>
0017 #include <drm/drm_simple_kms_helper.h>
0018
0019 #include "xen_drm_front_cfg.h"
0020
0021 struct drm_device;
0022 struct drm_framebuffer;
0023 struct drm_gem_object;
0024 struct drm_pending_vblank_event;
0025
0026 /**
0027  * DOC: Driver modes of operation in terms of display buffers used
0028  *
0029  * Depending on the requirements for the para-virtualized environment, namely
0030  * requirements dictated by the accompanying DRM/(v)GPU drivers running in both
0031  * host and guest environments, display buffers can be allocated by either
0032  * frontend driver or backend.
0033  */
0034
0035 /**
0036  * DOC: Buffers allocated by the frontend driver
0037  *
0038  * In this mode of operation driver allocates buffers from system memory.
0039  *
0040  * Note! If used with accompanying DRM/(v)GPU drivers this mode of operation
0041  * may require IOMMU support on the platform, so accompanying DRM/vGPU
0042  * hardware can still reach display buffer memory while importing PRIME
0043  * buffers from the frontend driver.
0044  */
0045
0046 /**
0047  * DOC: Buffers allocated by the backend
0048  *
0049  * This mode of operation is run-time configured via guest domain configuration
0050  * through XenStore entries.
0051  *
0052  * For systems which do not provide IOMMU support, but having specific
0053  * requirements for display buffers it is possible to allocate such buffers
0054  * at backend side and share those with the frontend.
0055  * For example, if host domain is 1:1 mapped and has DRM/GPU hardware expecting
0056  * physically contiguous memory, this allows implementing zero-copying
0057  * use-cases.
0058  *
0059  * Note, while using this scenario the following should be considered:
0060  *
0061  * #. If guest domain dies then pages/grants received from the backend
0062  *    cannot be claimed back
0063  *
0064  * #. Misbehaving guest may send too many requests to the
0065  *    backend exhausting its grant references and memory
0066  *    (consider this from security POV)
0067  */
0068
0069 /**
0070  * DOC: Driver limitations
0071  *
0072  * #. Only primary plane without additional properties is supported.
0073  *
0074  * #. Only one video mode per connector supported which is configured
0075  *    via XenStore.
0076  *
0077  * #. All CRTCs operate at fixed frequency of 60Hz.
0078  */
0079
0080 /* timeout in ms to wait for backend to respond */
0081 #define XEN_DRM_FRONT_WAIT_BACK_MS  3000
0082
0083 struct xen_drm_front_info {
0084     struct xenbus_device *xb_dev;
0085     struct xen_drm_front_drm_info *drm_info;
0086
0087     /* to protect data between backend IO code and interrupt handler */
0088     spinlock_t io_lock;
0089
0090     int num_evt_pairs;
0091     struct xen_drm_front_evtchnl_pair *evt_pairs;
0092     struct xen_drm_front_cfg cfg;
0093
0094     /* display buffers */
0095     struct list_head dbuf_list;
0096 };
0097
0098 struct xen_drm_front_drm_pipeline {
0099     struct xen_drm_front_drm_info *drm_info;
0100
0101     int index;
0102
0103     struct drm_simple_display_pipe pipe;
0104
0105     struct drm_connector conn;
0106     /* These are only for connector mode checking */
0107     int width, height;
0108
0109     struct drm_pending_vblank_event *pending_event;
0110
0111     struct delayed_work pflip_to_worker;
0112
0113     bool conn_connected;
0114 };
0115
0116 struct xen_drm_front_drm_info {
0117     struct xen_drm_front_info *front_info;
0118     struct drm_device *drm_dev;
0119
0120     struct xen_drm_front_drm_pipeline pipeline[XEN_DRM_FRONT_MAX_CRTCS];
0121 };
0122
0123 static inline u64 xen_drm_front_fb_to_cookie(struct drm_framebuffer *fb)
0124 {
0125     return (uintptr_t)fb;
0126 }
0127
0128 static inline u64 xen_drm_front_dbuf_to_cookie(struct drm_gem_object *gem_obj)
0129 {
0130     return (uintptr_t)gem_obj;
0131 }
0132
0133 int xen_drm_front_mode_set(struct xen_drm_front_drm_pipeline *pipeline,
0134                u32 x, u32 y, u32 width, u32 height,
0135                u32 bpp, u64 fb_cookie);
0136
0137 int xen_drm_front_dbuf_create(struct xen_drm_front_info *front_info,
0138                   u64 dbuf_cookie, u32 width, u32 height,
0139                   u32 bpp, u64 size, u32 offset, struct page **pages);
0140
0141 int xen_drm_front_fb_attach(struct xen_drm_front_info *front_info,
0142                 u64 dbuf_cookie, u64 fb_cookie, u32 width,
0143                 u32 height, u32 pixel_format);
0144
0145 int xen_drm_front_fb_detach(struct xen_drm_front_info *front_info,
0146                 u64 fb_cookie);
0147
0148 int xen_drm_front_page_flip(struct xen_drm_front_info *front_info,
0149                 int conn_idx, u64 fb_cookie);
0150
0151 void xen_drm_front_on_frame_done(struct xen_drm_front_info *front_info,
0152                  int conn_idx, u64 fb_cookie);
0153
0154 void xen_drm_front_gem_object_free(struct drm_gem_object *obj);
0155
0156 #endif /* __XEN_DRM_FRONT_H_ */