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1/* exynos_drm_iommu.c
2 *
3 * Copyright (c) 2012 Samsung Electronics Co., Ltd.
4 * Author: Inki Dae <inki.dae@samsung.com>
5 *
6 * This program is free software; you can redistribute  it and/or modify it
7 * under  the terms of  the GNU General  Public License as published by the
8 * Free Software Foundation;  either version 2 of the  License, or (at your
9 * option) any later version.
10 */
11
12#include <drmP.h>
13#include <drm/exynos_drm.h>
14
15#include <linux/dma-mapping.h>
16#include <linux/iommu.h>
17#include <linux/kref.h>
18
19#include <asm/dma-iommu.h>
20
21#include "exynos_drm_drv.h"
22#include "exynos_drm_iommu.h"
23
24/*
25 * drm_create_iommu_mapping - create a mapping structure
26 *
27 * @drm_dev: DRM device
28 */
29int drm_create_iommu_mapping(struct drm_device *drm_dev)
30{
31	struct dma_iommu_mapping *mapping = NULL;
32	struct exynos_drm_private *priv = drm_dev->dev_private;
33	struct device *dev = drm_dev->dev;
34
35	if (!priv->da_start)
36		priv->da_start = EXYNOS_DEV_ADDR_START;
37	if (!priv->da_space_size)
38		priv->da_space_size = EXYNOS_DEV_ADDR_SIZE;
39
40	mapping = arm_iommu_create_mapping(&platform_bus_type, priv->da_start,
41						priv->da_space_size);
42
43	if (IS_ERR(mapping))
44		return PTR_ERR(mapping);
45
46	dev->dma_parms = devm_kzalloc(dev, sizeof(*dev->dma_parms),
47					GFP_KERNEL);
48	if (!dev->dma_parms)
49		goto error;
50
51	dma_set_max_seg_size(dev, 0xffffffffu);
52	dev->archdata.mapping = mapping;
53
54	return 0;
55error:
56	arm_iommu_release_mapping(mapping);
57	return -ENOMEM;
58}
59
60/*
61 * drm_release_iommu_mapping - release iommu mapping structure
62 *
63 * @drm_dev: DRM device
64 *
65 * if mapping->kref becomes 0 then all things related to iommu mapping
66 * will be released
67 */
68void drm_release_iommu_mapping(struct drm_device *drm_dev)
69{
70	struct device *dev = drm_dev->dev;
71
72	arm_iommu_release_mapping(dev->archdata.mapping);
73}
74
75/*
76 * drm_iommu_attach_device- attach device to iommu mapping
77 *
78 * @drm_dev: DRM device
79 * @subdrv_dev: device to be attach
80 *
81 * This function should be called by sub drivers to attach it to iommu
82 * mapping.
83 */
84int drm_iommu_attach_device(struct drm_device *drm_dev,
85				struct device *subdrv_dev)
86{
87	struct device *dev = drm_dev->dev;
88	int ret;
89
90	if (!dev->archdata.mapping) {
91		DRM_ERROR("iommu_mapping is null.\n");
92		return -EFAULT;
93	}
94
95	subdrv_dev->dma_parms = devm_kzalloc(subdrv_dev,
96					sizeof(*subdrv_dev->dma_parms),
97					GFP_KERNEL);
98	if (!subdrv_dev->dma_parms)
99		return -ENOMEM;
100
101	dma_set_max_seg_size(subdrv_dev, 0xffffffffu);
102
103	ret = arm_iommu_attach_device(subdrv_dev, dev->archdata.mapping);
104	if (ret < 0) {
105		DRM_DEBUG_KMS("failed iommu attach.\n");
106		return ret;
107	}
108
109	/*
110	 * Set dma_ops to drm_device just one time.
111	 *
112	 * The dma mapping api needs device object and the api is used
113	 * to allocate physial memory and map it with iommu table.
114	 * If iommu attach succeeded, the sub driver would have dma_ops
115	 * for iommu and also all sub drivers have same dma_ops.
116	 */
117	if (!dev->archdata.dma_ops)
118		dev->archdata.dma_ops = subdrv_dev->archdata.dma_ops;
119
120	return 0;
121}
122
123/*
124 * drm_iommu_detach_device -detach device address space mapping from device
125 *
126 * @drm_dev: DRM device
127 * @subdrv_dev: device to be detached
128 *
129 * This function should be called by sub drivers to detach it from iommu
130 * mapping
131 */
132void drm_iommu_detach_device(struct drm_device *drm_dev,
133				struct device *subdrv_dev)
134{
135	struct device *dev = drm_dev->dev;
136	struct dma_iommu_mapping *mapping = dev->archdata.mapping;
137
138	if (!mapping || !mapping->domain)
139		return;
140
141	iommu_detach_device(mapping->domain, subdrv_dev);
142	drm_release_iommu_mapping(drm_dev);
143}
144