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);
27 	if (IS_ERR(sg))
28 		return sg;
29 
30 	/* this must be after omap_gem_pin() to ensure we have pages attached */
31 	omap_gem_dma_sync_buffer(obj, dir);
32 
33 	return sg;
34 }
35 
36 static void omap_gem_unmap_dma_buf(struct dma_buf_attachment *attachment,
37 		struct sg_table *sg, enum dma_data_direction dir)
38 {
39 	struct drm_gem_object *obj = attachment->dmabuf->priv;
40 	omap_gem_put_sg(obj, sg);
41 }
42 
43 static int omap_gem_dmabuf_begin_cpu_access(struct dma_buf *buffer,
44 		enum dma_data_direction dir)
45 {
46 	struct drm_gem_object *obj = buffer->priv;
47 	struct page **pages;
48 	if (omap_gem_flags(obj) & OMAP_BO_TILED_MASK) {
49 		/* TODO we would need to pin at least part of the buffer to
50 		 * get de-tiled view.  For now just reject it.
51 		 */
52 		return -ENOMEM;
53 	}
54 	/* make sure we have the pages: */
55 	return omap_gem_get_pages(obj, &pages, true);
56 }
57 
58 static int omap_gem_dmabuf_end_cpu_access(struct dma_buf *buffer,
59 					  enum dma_data_direction dir)
60 {
61 	struct drm_gem_object *obj = buffer->priv;
62 	omap_gem_put_pages(obj);
63 	return 0;
64 }
65 
66 static int omap_gem_dmabuf_mmap(struct dma_buf *buffer,
67 		struct vm_area_struct *vma)
68 {
69 	struct drm_gem_object *obj = buffer->priv;
70 	int ret = 0;
71 
72 	ret = drm_gem_mmap_obj(obj, omap_gem_mmap_size(obj), vma);
73 	if (ret < 0)
74 		return ret;
75 
76 	return omap_gem_mmap_obj(obj, vma);
77 }
78 
79 static const struct dma_buf_ops omap_dmabuf_ops = {
80 	.map_dma_buf = omap_gem_map_dma_buf,
81 	.unmap_dma_buf = omap_gem_unmap_dma_buf,
82 	.release = drm_gem_dmabuf_release,
83 	.begin_cpu_access = omap_gem_dmabuf_begin_cpu_access,
84 	.end_cpu_access = omap_gem_dmabuf_end_cpu_access,
85 	.mmap = omap_gem_dmabuf_mmap,
86 };
87 
88 struct dma_buf *omap_gem_prime_export(struct drm_gem_object *obj, int flags)
89 {
90 	DEFINE_DMA_BUF_EXPORT_INFO(exp_info);
91 
92 	exp_info.ops = &omap_dmabuf_ops;
93 	exp_info.size = omap_gem_mmap_size(obj);
94 	exp_info.flags = flags;
95 	exp_info.priv = obj;
96 	exp_info.resv = obj->resv;
97 
98 	return drm_gem_dmabuf_export(obj->dev, &exp_info);
99 }
100 
101 /* -----------------------------------------------------------------------------
102  * DMABUF Import
103  */
104 
105 struct drm_gem_object *omap_gem_prime_import(struct drm_device *dev,
106 					     struct dma_buf *dma_buf)
107 {
108 	struct dma_buf_attachment *attach;
109 	struct drm_gem_object *obj;
110 	struct sg_table *sgt;
111 	int ret;
112 
113 	if (dma_buf->ops == &omap_dmabuf_ops) {
114 		obj = dma_buf->priv;
115 		if (obj->dev == dev) {
116 			/*
117 			 * Importing dmabuf exported from out own gem increases
118 			 * refcount on gem itself instead of f_count of dmabuf.
119 			 */
120 			drm_gem_object_get(obj);
121 			return obj;
122 		}
123 	}
124 
125 	attach = dma_buf_attach(dma_buf, dev->dev);
126 	if (IS_ERR(attach))
127 		return ERR_CAST(attach);
128 
129 	get_dma_buf(dma_buf);
130 
131 	sgt = dma_buf_map_attachment(attach, DMA_TO_DEVICE);
132 	if (IS_ERR(sgt)) {
133 		ret = PTR_ERR(sgt);
134 		goto fail_detach;
135 	}
136 
137 	obj = omap_gem_new_dmabuf(dev, dma_buf->size, sgt);
138 	if (IS_ERR(obj)) {
139 		ret = PTR_ERR(obj);
140 		goto fail_unmap;
141 	}
142 
143 	obj->import_attach = attach;
144 
145 	return obj;
146 
147 fail_unmap:
148 	dma_buf_unmap_attachment(attach, sgt, DMA_TO_DEVICE);
149 fail_detach:
150 	dma_buf_detach(dma_buf, attach);
151 	dma_buf_put(dma_buf);
152 
153 	return ERR_PTR(ret);
154 }
155