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