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 */
 42static 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 */
 83static 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
 95int 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
126void 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
133void 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}