drivers/gpu/drm/xen/xen_drm_front.h

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