// SPDX-License-Identifier: GPL-2.0
//
// Copyright (c) 2012 Samsung Electronics Co., Ltd.
// Author: Inki Dae <inki.dae@samsung.com>
// Author: Andrzej Hajda <a.hajda@samsung.com>

#include <linux/dma-map-ops.h>
#include <linux/iommu.h>
#include <linux/platform_device.h>

#include <drm/drm_print.h>
#include <drm/exynos_drm.h>

#include "exynos_drm_drv.h"

#if defined(CONFIG_ARM_DMA_USE_IOMMU)
#include <asm/dma-iommu.h>
#else
#define arm_iommu_create_mapping(...)   ({ NULL; })
#define arm_iommu_attach_device(...)    ({ -ENODEV; })
#define arm_iommu_release_mapping(...)  ({ })
#define arm_iommu_detach_device(...)    ({ })
#define to_dma_iommu_mapping(dev) NULL
#endif

#if !defined(CONFIG_IOMMU_DMA)
#define iommu_dma_init_domain(...) ({ -EINVAL; })
#endif

#define EXYNOS_DEV_ADDR_START   0x20000000
#define EXYNOS_DEV_ADDR_SIZE    0x40000000

/*
 * drm_iommu_attach_device- attach device to iommu mapping
 *
 * @drm_dev: DRM device
 * @subdrv_dev: device to be attach
 *
 * This function should be called by sub drivers to attach it to iommu
 * mapping.
 */
static int drm_iommu_attach_device(struct drm_device *drm_dev,
                                struct device *subdrv_dev, void **dma_priv)
{
        struct exynos_drm_private *priv = drm_dev->dev_private;
        int ret = 0;

        if (get_dma_ops(priv->dma_dev) != get_dma_ops(subdrv_dev)) {
                DRM_DEV_ERROR(subdrv_dev, "Device %s lacks support for IOMMU\n",
                          dev_name(subdrv_dev));
                return -EINVAL;
        }

        dma_set_max_seg_size(subdrv_dev, DMA_BIT_MASK(32));
        if (IS_ENABLED(CONFIG_ARM_DMA_USE_IOMMU)) {
                /*
                 * Keep the original DMA mapping of the sub-device and
                 * restore it on Exynos DRM detach, otherwise the DMA
                 * framework considers it as IOMMU-less during the next
                 * probe (in case of deferred probe or modular build)
                 */
                *dma_priv = to_dma_iommu_mapping(subdrv_dev);
                if (*dma_priv)
                        arm_iommu_detach_device(subdrv_dev);

                ret = arm_iommu_attach_device(subdrv_dev, priv->mapping);
        } else if (IS_ENABLED(CONFIG_IOMMU_DMA)) {
                ret = iommu_attach_device(priv->mapping, subdrv_dev);
        }

        return ret;
}

/*
 * drm_iommu_detach_device -detach device address space mapping from device
 *
 * @drm_dev: DRM device
 * @subdrv_dev: device to be detached
 *
 * This function should be called by sub drivers to detach it from iommu
 * mapping
 */
static void drm_iommu_detach_device(struct drm_device *drm_dev,
                                    struct device *subdrv_dev, void **dma_priv)
{
        struct exynos_drm_private *priv = drm_dev->dev_private;

        if (IS_ENABLED(CONFIG_ARM_DMA_USE_IOMMU)) {
                arm_iommu_detach_device(subdrv_dev);
                arm_iommu_attach_device(subdrv_dev, *dma_priv);
        } else if (IS_ENABLED(CONFIG_IOMMU_DMA))
                iommu_detach_device(priv->mapping, subdrv_dev);
}

int exynos_drm_register_dma(struct drm_device *drm, struct device *dev,
                            void **dma_priv)
{
        struct exynos_drm_private *priv = drm->dev_private;

        if (!priv->dma_dev) {
                priv->dma_dev = dev;
                DRM_INFO("Exynos DRM: using %s device for DMA mapping operations\n",
                         dev_name(dev));
        }

        if (!IS_ENABLED(CONFIG_EXYNOS_IOMMU))
                return 0;

        if (!priv->mapping) {
                void *mapping = NULL;

                if (IS_ENABLED(CONFIG_ARM_DMA_USE_IOMMU))
                        mapping = arm_iommu_create_mapping(dev,
                                EXYNOS_DEV_ADDR_START, EXYNOS_DEV_ADDR_SIZE);
                else if (IS_ENABLED(CONFIG_IOMMU_DMA))
                        mapping = iommu_get_domain_for_dev(priv->dma_dev);

                if (!mapping)
                        return -ENODEV;
                priv->mapping = mapping;
        }

        return drm_iommu_attach_device(drm, dev, dma_priv);
}

void exynos_drm_unregister_dma(struct drm_device *drm, struct device *dev,
                               void **dma_priv)
{
        if (IS_ENABLED(CONFIG_EXYNOS_IOMMU))
                drm_iommu_detach_device(drm, dev, dma_priv);
}

void exynos_drm_cleanup_dma(struct drm_device *drm)
{
        struct exynos_drm_private *priv = drm->dev_private;

        if (!IS_ENABLED(CONFIG_EXYNOS_IOMMU))
                return;

        arm_iommu_release_mapping(priv->mapping);
        priv->mapping = NULL;
        priv->dma_dev = NULL;
}