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  */
43 static 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  */
84 static 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 
96 int 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;
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 (IS_ERR(mapping))
120 			return PTR_ERR(mapping);
121 		priv->mapping = mapping;
122 	}
123 
124 	return drm_iommu_attach_device(drm, dev, dma_priv);
125 }
126 
127 void 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 
134 void 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