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-mapping.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
 34static inline int configure_dma_max_seg_size(struct device *dev)
 35{
 36	if (!dev->dma_parms)
 37		dev->dma_parms = kzalloc(sizeof(*dev->dma_parms), GFP_KERNEL);
 38	if (!dev->dma_parms)
 39		return -ENOMEM;
 40
 41	dma_set_max_seg_size(dev, DMA_BIT_MASK(32));
 42	return 0;
 43}
 44
 45static inline void clear_dma_max_seg_size(struct device *dev)
 46{
 47	kfree(dev->dma_parms);
 48	dev->dma_parms = NULL;
 49}
 50
 51/*
 52 * drm_iommu_attach_device- attach device to iommu mapping
 53 *
 54 * @drm_dev: DRM device
 55 * @subdrv_dev: device to be attach
 56 *
 57 * This function should be called by sub drivers to attach it to iommu
 58 * mapping.
 59 */
 60static int drm_iommu_attach_device(struct drm_device *drm_dev,
 61				struct device *subdrv_dev, void **dma_priv)
 62{
 63	struct exynos_drm_private *priv = drm_dev->dev_private;
 64	int ret = 0;
 65
 66	if (get_dma_ops(priv->dma_dev) != get_dma_ops(subdrv_dev)) {
 67		DRM_DEV_ERROR(subdrv_dev, "Device %s lacks support for IOMMU\n",
 68			  dev_name(subdrv_dev));
 69		return -EINVAL;
 70	}
 71
 72	ret = configure_dma_max_seg_size(subdrv_dev);
 73	if (ret)
 74		return ret;
 75
 76	if (IS_ENABLED(CONFIG_ARM_DMA_USE_IOMMU)) {
 77		/*
 78		 * Keep the original DMA mapping of the sub-device and
 79		 * restore it on Exynos DRM detach, otherwise the DMA
 80		 * framework considers it as IOMMU-less during the next
 81		 * probe (in case of deferred probe or modular build)
 82		 */
 83		*dma_priv = to_dma_iommu_mapping(subdrv_dev);
 84		if (*dma_priv)
 85			arm_iommu_detach_device(subdrv_dev);
 86
 87		ret = arm_iommu_attach_device(subdrv_dev, priv->mapping);
 88	} else if (IS_ENABLED(CONFIG_IOMMU_DMA)) {
 89		ret = iommu_attach_device(priv->mapping, subdrv_dev);
 90	}
 91
 92	if (ret)
 93		clear_dma_max_seg_size(subdrv_dev);
 94
 95	return ret;
 96}
 97
 98/*
 99 * drm_iommu_detach_device -detach device address space mapping from device
100 *
101 * @drm_dev: DRM device
102 * @subdrv_dev: device to be detached
103 *
104 * This function should be called by sub drivers to detach it from iommu
105 * mapping
106 */
107static void drm_iommu_detach_device(struct drm_device *drm_dev,
108				    struct device *subdrv_dev, void **dma_priv)
109{
110	struct exynos_drm_private *priv = drm_dev->dev_private;
111
112	if (IS_ENABLED(CONFIG_ARM_DMA_USE_IOMMU)) {
113		arm_iommu_detach_device(subdrv_dev);
114		arm_iommu_attach_device(subdrv_dev, *dma_priv);
115	} else if (IS_ENABLED(CONFIG_IOMMU_DMA))
116		iommu_detach_device(priv->mapping, subdrv_dev);
117
118	clear_dma_max_seg_size(subdrv_dev);
119}
120
121int exynos_drm_register_dma(struct drm_device *drm, struct device *dev,
122			    void **dma_priv)
123{
124	struct exynos_drm_private *priv = drm->dev_private;
125
126	if (!priv->dma_dev) {
127		priv->dma_dev = dev;
128		DRM_INFO("Exynos DRM: using %s device for DMA mapping operations\n",
129			 dev_name(dev));
130	}
131
132	if (!IS_ENABLED(CONFIG_EXYNOS_IOMMU))
133		return 0;
134
135	if (!priv->mapping) {
136		void *mapping;
137
138		if (IS_ENABLED(CONFIG_ARM_DMA_USE_IOMMU))
139			mapping = arm_iommu_create_mapping(&platform_bus_type,
140				EXYNOS_DEV_ADDR_START, EXYNOS_DEV_ADDR_SIZE);
141		else if (IS_ENABLED(CONFIG_IOMMU_DMA))
142			mapping = iommu_get_domain_for_dev(priv->dma_dev);
143
144		if (IS_ERR(mapping))
145			return PTR_ERR(mapping);
146		priv->mapping = mapping;
147	}
148
149	return drm_iommu_attach_device(drm, dev, dma_priv);
150}
151
152void exynos_drm_unregister_dma(struct drm_device *drm, struct device *dev,
153			       void **dma_priv)
154{
155	if (IS_ENABLED(CONFIG_EXYNOS_IOMMU))
156		drm_iommu_detach_device(drm, dev, dma_priv);
157}
158
159void exynos_drm_cleanup_dma(struct drm_device *drm)
160{
161	struct exynos_drm_private *priv = drm->dev_private;
162
163	if (!IS_ENABLED(CONFIG_EXYNOS_IOMMU))
164		return;
165
166	arm_iommu_release_mapping(priv->mapping);
167	priv->mapping = NULL;
168	priv->dma_dev = NULL;
169}