1 // SPDX-License-Identifier: GPL-2.0-only
2 /*
3  * Copyright (C) 2011 Texas Instruments Incorporated - https://www.ti.com/
4  * Author: Rob Clark <rob.clark@linaro.org>
5  */
6 
7 #include <linux/dma-buf.h>
8 #include <linux/highmem.h>
9 
10 #include <drm/drm_prime.h>
11 
12 #include "omap_drv.h"
13 
14 MODULE_IMPORT_NS(DMA_BUF);
15 
16 /* -----------------------------------------------------------------------------
17  * DMABUF Export
18  */
19 
20 static struct sg_table *omap_gem_map_dma_buf(
21 		struct dma_buf_attachment *attachment,
22 		enum dma_data_direction dir)
23 {
24 	struct drm_gem_object *obj = attachment->dmabuf->priv;
25 	struct sg_table *sg;
26 	sg = omap_gem_get_sg(obj, dir);
27 	if (IS_ERR(sg))
28 		return sg;
29 
30 	return sg;
31 }
32 
33 static void omap_gem_unmap_dma_buf(struct dma_buf_attachment *attachment,
34 		struct sg_table *sg, enum dma_data_direction dir)
35 {
36 	struct drm_gem_object *obj = attachment->dmabuf->priv;
37 	omap_gem_put_sg(obj, sg);
38 }
39 
40 static int omap_gem_dmabuf_begin_cpu_access(struct dma_buf *buffer,
41 		enum dma_data_direction dir)
42 {
43 	struct drm_gem_object *obj = buffer->priv;
44 	struct page **pages;
45 	if (omap_gem_flags(obj) & OMAP_BO_TILED_MASK) {
46 		/* TODO we would need to pin at least part of the buffer to
47 		 * get de-tiled view.  For now just reject it.
48 		 */
49 		return -ENOMEM;
50 	}
51 	/* make sure we have the pages: */
52 	return omap_gem_get_pages(obj, &pages, true);
53 }
54 
55 static int omap_gem_dmabuf_end_cpu_access(struct dma_buf *buffer,
56 					  enum dma_data_direction dir)
57 {
58 	struct drm_gem_object *obj = buffer->priv;
59 	omap_gem_put_pages(obj);
60 	return 0;
61 }
62 
63 static int omap_gem_dmabuf_mmap(struct dma_buf *buffer,
64 		struct vm_area_struct *vma)
65 {
66 	struct drm_gem_object *obj = buffer->priv;
67 	int ret = 0;
68 
69 	dma_resv_assert_held(buffer->resv);
70 
71 	ret = drm_gem_mmap_obj(obj, omap_gem_mmap_size(obj), vma);
72 	if (ret < 0)
73 		return ret;
74 
75 	return omap_gem_mmap_obj(obj, vma);
76 }
77 
78 static const struct dma_buf_ops omap_dmabuf_ops = {
79 	.map_dma_buf = omap_gem_map_dma_buf,
80 	.unmap_dma_buf = omap_gem_unmap_dma_buf,
81 	.release = drm_gem_dmabuf_release,
82 	.begin_cpu_access = omap_gem_dmabuf_begin_cpu_access,
83 	.end_cpu_access = omap_gem_dmabuf_end_cpu_access,
84 	.mmap = omap_gem_dmabuf_mmap,
85 };
86 
87 struct dma_buf *omap_gem_prime_export(struct drm_gem_object *obj, int flags)
88 {
89 	DEFINE_DMA_BUF_EXPORT_INFO(exp_info);
90 
91 	exp_info.ops = &omap_dmabuf_ops;
92 	exp_info.size = omap_gem_mmap_size(obj);
93 	exp_info.flags = flags;
94 	exp_info.priv = obj;
95 	exp_info.resv = obj->resv;
96 
97 	return drm_gem_dmabuf_export(obj->dev, &exp_info);
98 }
99 
100 /* -----------------------------------------------------------------------------
101  * DMABUF Import
102  */
103 
104 struct drm_gem_object *omap_gem_prime_import(struct drm_device *dev,
105 					     struct dma_buf *dma_buf)
106 {
107 	struct dma_buf_attachment *attach;
108 	struct drm_gem_object *obj;
109 	struct sg_table *sgt;
110 	int ret;
111 
112 	if (dma_buf->ops == &omap_dmabuf_ops) {
113 		obj = dma_buf->priv;
114 		if (obj->dev == dev) {
115 			/*
116 			 * Importing dmabuf exported from out own gem increases
117 			 * refcount on gem itself instead of f_count of dmabuf.
118 			 */
119 			drm_gem_object_get(obj);
120 			return obj;
121 		}
122 	}
123 
124 	attach = dma_buf_attach(dma_buf, dev->dev);
125 	if (IS_ERR(attach))
126 		return ERR_CAST(attach);
127 
128 	get_dma_buf(dma_buf);
129 
130 	sgt = dma_buf_map_attachment_unlocked(attach, DMA_TO_DEVICE);
131 	if (IS_ERR(sgt)) {
132 		ret = PTR_ERR(sgt);
133 		goto fail_detach;
134 	}
135 
136 	obj = omap_gem_new_dmabuf(dev, dma_buf->size, sgt);
137 	if (IS_ERR(obj)) {
138 		ret = PTR_ERR(obj);
139 		goto fail_unmap;
140 	}
141 
142 	obj->import_attach = attach;
143 
144 	return obj;
145 
146 fail_unmap:
147 	dma_buf_unmap_attachment_unlocked(attach, sgt, DMA_TO_DEVICE);
148 fail_detach:
149 	dma_buf_detach(dma_buf, attach);
150 	dma_buf_put(dma_buf);
151 
152 	return ERR_PTR(ret);
153 }
154