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)
 62{
 63	struct exynos_drm_private *priv = drm_dev->dev_private;
 64	int ret;
 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		if (to_dma_iommu_mapping(subdrv_dev))
 78			arm_iommu_detach_device(subdrv_dev);
 79
 80		ret = arm_iommu_attach_device(subdrv_dev, priv->mapping);
 81	} else if (IS_ENABLED(CONFIG_IOMMU_DMA)) {
 82		ret = iommu_attach_device(priv->mapping, subdrv_dev);
 83	}
 84
 85	if (ret)
 86		clear_dma_max_seg_size(subdrv_dev);
 87
 88	return 0;
 89}
 90
 91/*
 92 * drm_iommu_detach_device -detach device address space mapping from device
 93 *
 94 * @drm_dev: DRM device
 95 * @subdrv_dev: device to be detached
 96 *
 97 * This function should be called by sub drivers to detach it from iommu
 98 * mapping
 99 */
100static void drm_iommu_detach_device(struct drm_device *drm_dev,
101				struct device *subdrv_dev)
102{
103	struct exynos_drm_private *priv = drm_dev->dev_private;
104
105	if (IS_ENABLED(CONFIG_ARM_DMA_USE_IOMMU))
106		arm_iommu_detach_device(subdrv_dev);
107	else if (IS_ENABLED(CONFIG_IOMMU_DMA))
108		iommu_detach_device(priv->mapping, subdrv_dev);
109
110	clear_dma_max_seg_size(subdrv_dev);
111}
112
113int exynos_drm_register_dma(struct drm_device *drm, struct device *dev)
114{
115	struct exynos_drm_private *priv = drm->dev_private;
116
117	if (!priv->dma_dev) {
118		priv->dma_dev = dev;
119		DRM_INFO("Exynos DRM: using %s device for DMA mapping operations\n",
120			 dev_name(dev));
121	}
122
123	if (!IS_ENABLED(CONFIG_EXYNOS_IOMMU))
124		return 0;
125
126	if (!priv->mapping) {
127		void *mapping;
128
129		if (IS_ENABLED(CONFIG_ARM_DMA_USE_IOMMU))
130			mapping = arm_iommu_create_mapping(&platform_bus_type,
131				EXYNOS_DEV_ADDR_START, EXYNOS_DEV_ADDR_SIZE);
132		else if (IS_ENABLED(CONFIG_IOMMU_DMA))
133			mapping = iommu_get_domain_for_dev(priv->dma_dev);
134
135		if (IS_ERR(mapping))
136			return PTR_ERR(mapping);
137		priv->mapping = mapping;
138	}
139
140	return drm_iommu_attach_device(drm, dev);
141}
142
143void exynos_drm_unregister_dma(struct drm_device *drm, struct device *dev)
144{
145	if (IS_ENABLED(CONFIG_EXYNOS_IOMMU))
146		drm_iommu_detach_device(drm, dev);
147}
148
149void exynos_drm_cleanup_dma(struct drm_device *drm)
150{
151	struct exynos_drm_private *priv = drm->dev_private;
152
153	if (!IS_ENABLED(CONFIG_EXYNOS_IOMMU))
154		return;
155
156	arm_iommu_release_mapping(priv->mapping);
157	priv->mapping = NULL;
158	priv->dma_dev = NULL;
159}