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;
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		else
119			mapping = ERR_PTR(-ENODEV);
120
121		if (IS_ERR(mapping))
122			return PTR_ERR(mapping);
123		priv->mapping = mapping;
124	}
125
126	return drm_iommu_attach_device(drm, dev, dma_priv);
127}
128
129void exynos_drm_unregister_dma(struct drm_device *drm, struct device *dev,
130			       void **dma_priv)
131{
132	if (IS_ENABLED(CONFIG_EXYNOS_IOMMU))
133		drm_iommu_detach_device(drm, dev, dma_priv);
134}
135
136void exynos_drm_cleanup_dma(struct drm_device *drm)
137{
138	struct exynos_drm_private *priv = drm->dev_private;
139
140	if (!IS_ENABLED(CONFIG_EXYNOS_IOMMU))
141		return;
142
143	arm_iommu_release_mapping(priv->mapping);
144	priv->mapping = NULL;
145	priv->dma_dev = NULL;
146}