1// SPDX-License-Identifier: GPL-2.0
2//
3// Copyright (c) 2012 Samsung Electronics Co., Ltd.
4// Author: Inki Dae <inki.dae@samsung.com>
5// Author: Andrzej Hajda <a.hajda@samsung.com>
6
7#include <linux/dma-iommu.h>
8#include <linux/dma-map-ops.h>
9#include <linux/iommu.h>
10#include <linux/platform_device.h>
11
12#include <drm/drm_print.h>
13#include <drm/exynos_drm.h>
14
15#include "exynos_drm_drv.h"
16
17#if defined(CONFIG_ARM_DMA_USE_IOMMU)
18#include <asm/dma-iommu.h>
19#else
20#define arm_iommu_create_mapping(...)	({ NULL; })
21#define arm_iommu_attach_device(...)	({ -ENODEV; })
22#define arm_iommu_release_mapping(...)	({ })
23#define arm_iommu_detach_device(...)	({ })
24#define to_dma_iommu_mapping(dev) NULL
25#endif
26
27#if !defined(CONFIG_IOMMU_DMA)
28#define iommu_dma_init_domain(...) ({ -EINVAL; })
29#endif
30
31#define EXYNOS_DEV_ADDR_START	0x20000000
32#define EXYNOS_DEV_ADDR_SIZE	0x40000000
33
34/*
35 * drm_iommu_attach_device- attach device to iommu mapping
36 *
37 * @drm_dev: DRM device
38 * @subdrv_dev: device to be attach
39 *
40 * This function should be called by sub drivers to attach it to iommu
41 * mapping.
42 */
43static int drm_iommu_attach_device(struct drm_device *drm_dev,
44				struct device *subdrv_dev, void **dma_priv)
45{
46	struct exynos_drm_private *priv = drm_dev->dev_private;
47	int ret = 0;
48
49	if (get_dma_ops(priv->dma_dev) != get_dma_ops(subdrv_dev)) {
50		DRM_DEV_ERROR(subdrv_dev, "Device %s lacks support for IOMMU\n",
51			  dev_name(subdrv_dev));
52		return -EINVAL;
53	}
54
55	dma_set_max_seg_size(subdrv_dev, DMA_BIT_MASK(32));
56	if (IS_ENABLED(CONFIG_ARM_DMA_USE_IOMMU)) {
57		/*
58		 * Keep the original DMA mapping of the sub-device and
59		 * restore it on Exynos DRM detach, otherwise the DMA
60		 * framework considers it as IOMMU-less during the next
61		 * probe (in case of deferred probe or modular build)
62		 */
63		*dma_priv = to_dma_iommu_mapping(subdrv_dev);
64		if (*dma_priv)
65			arm_iommu_detach_device(subdrv_dev);
66
67		ret = arm_iommu_attach_device(subdrv_dev, priv->mapping);
68	} else if (IS_ENABLED(CONFIG_IOMMU_DMA)) {
69		ret = iommu_attach_device(priv->mapping, subdrv_dev);
70	}
71
72	return ret;
73}
74
75/*
76 * drm_iommu_detach_device -detach device address space mapping from device
77 *
78 * @drm_dev: DRM device
79 * @subdrv_dev: device to be detached
80 *
81 * This function should be called by sub drivers to detach it from iommu
82 * mapping
83 */
84static void drm_iommu_detach_device(struct drm_device *drm_dev,
85				    struct device *subdrv_dev, void **dma_priv)
86{
87	struct exynos_drm_private *priv = drm_dev->dev_private;
88
89	if (IS_ENABLED(CONFIG_ARM_DMA_USE_IOMMU)) {
90		arm_iommu_detach_device(subdrv_dev);
91		arm_iommu_attach_device(subdrv_dev, *dma_priv);
92	} else if (IS_ENABLED(CONFIG_IOMMU_DMA))
93		iommu_detach_device(priv->mapping, subdrv_dev);
94}
95
96int exynos_drm_register_dma(struct drm_device *drm, struct device *dev,
97			    void **dma_priv)
98{
99	struct exynos_drm_private *priv = drm->dev_private;
100
101	if (!priv->dma_dev) {
102		priv->dma_dev = dev;
103		DRM_INFO("Exynos DRM: using %s device for DMA mapping operations\n",
104			 dev_name(dev));
105	}
106
107	if (!IS_ENABLED(CONFIG_EXYNOS_IOMMU))
108		return 0;
109
110	if (!priv->mapping) {
111		void *mapping = NULL;
112
113		if (IS_ENABLED(CONFIG_ARM_DMA_USE_IOMMU))
114			mapping = arm_iommu_create_mapping(&platform_bus_type,
115				EXYNOS_DEV_ADDR_START, EXYNOS_DEV_ADDR_SIZE);
116		else if (IS_ENABLED(CONFIG_IOMMU_DMA))
117			mapping = iommu_get_domain_for_dev(priv->dma_dev);
118
119		if (!mapping)
120			return -ENODEV;
121		priv->mapping = mapping;
122	}
123
124	return drm_iommu_attach_device(drm, dev, dma_priv);
125}
126
127void exynos_drm_unregister_dma(struct drm_device *drm, struct device *dev,
128			       void **dma_priv)
129{
130	if (IS_ENABLED(CONFIG_EXYNOS_IOMMU))
131		drm_iommu_detach_device(drm, dev, dma_priv);
132}
133
134void exynos_drm_cleanup_dma(struct drm_device *drm)
135{
136	struct exynos_drm_private *priv = drm->dev_private;
137
138	if (!IS_ENABLED(CONFIG_EXYNOS_IOMMU))
139		return;
140
141	arm_iommu_release_mapping(priv->mapping);
142	priv->mapping = NULL;
143	priv->dma_dev = NULL;
144}
145