1/* exynos_drm_iommu.c
  2 *
  3 * Copyright (c) 2012 Samsung Electronics Co., Ltd.
  4 * Author: Inki Dae <inki.dae@samsung.com>
  5 *
  6 * This program is free software; you can redistribute  it and/or modify it
  7 * under  the terms of  the GNU General  Public License as published by the
  8 * Free Software Foundation;  either version 2 of the  License, or (at your
  9 * option) any later version.
 10 */
 11
 12#include <drmP.h>
 13#include <drm/exynos_drm.h>
 14
 15#include <linux/dma-mapping.h>
 16#include <linux/iommu.h>
 17#include <linux/kref.h>
 18
 19#include <asm/dma-iommu.h>
 20
 21#include "exynos_drm_drv.h"
 22#include "exynos_drm_iommu.h"
 23
 24/*
 25 * drm_create_iommu_mapping - create a mapping structure
 26 *
 27 * @drm_dev: DRM device
 28 */
 29int drm_create_iommu_mapping(struct drm_device *drm_dev)
 30{
 31	struct dma_iommu_mapping *mapping = NULL;
 32	struct exynos_drm_private *priv = drm_dev->dev_private;
 33	struct device *dev = drm_dev->dev;
 34
 35	if (!priv->da_start)
 36		priv->da_start = EXYNOS_DEV_ADDR_START;
 37	if (!priv->da_space_size)
 38		priv->da_space_size = EXYNOS_DEV_ADDR_SIZE;
 39
 40	mapping = arm_iommu_create_mapping(&platform_bus_type, priv->da_start,
 41						priv->da_space_size);
 42
 43	if (IS_ERR(mapping))
 44		return PTR_ERR(mapping);
 45
 46	dev->dma_parms = devm_kzalloc(dev, sizeof(*dev->dma_parms),
 47					GFP_KERNEL);
 48	if (!dev->dma_parms)
 49		goto error;
 50
 51	dma_set_max_seg_size(dev, 0xffffffffu);
 52	dev->archdata.mapping = mapping;
 53
 54	return 0;
 55error:
 56	arm_iommu_release_mapping(mapping);
 57	return -ENOMEM;
 58}
 59
 60/*
 61 * drm_release_iommu_mapping - release iommu mapping structure
 62 *
 63 * @drm_dev: DRM device
 64 *
 65 * if mapping->kref becomes 0 then all things related to iommu mapping
 66 * will be released
 67 */
 68void drm_release_iommu_mapping(struct drm_device *drm_dev)
 69{
 70	struct device *dev = drm_dev->dev;
 71
 72	arm_iommu_release_mapping(dev->archdata.mapping);
 73}
 74
 75/*
 76 * drm_iommu_attach_device- attach device to iommu mapping
 77 *
 78 * @drm_dev: DRM device
 79 * @subdrv_dev: device to be attach
 80 *
 81 * This function should be called by sub drivers to attach it to iommu
 82 * mapping.
 83 */
 84int drm_iommu_attach_device(struct drm_device *drm_dev,
 85				struct device *subdrv_dev)
 86{
 87	struct device *dev = drm_dev->dev;
 88	int ret;
 89
 90	if (!dev->archdata.mapping) {
 91		DRM_ERROR("iommu_mapping is null.\n");
 92		return -EFAULT;
 93	}
 94
 95	subdrv_dev->dma_parms = devm_kzalloc(subdrv_dev,
 96					sizeof(*subdrv_dev->dma_parms),
 97					GFP_KERNEL);
 98	if (!subdrv_dev->dma_parms)
 99		return -ENOMEM;
100
101	dma_set_max_seg_size(subdrv_dev, 0xffffffffu);
102
103	ret = arm_iommu_attach_device(subdrv_dev, dev->archdata.mapping);
104	if (ret < 0) {
105		DRM_DEBUG_KMS("failed iommu attach.\n");
106		return ret;
107	}
108
109	/*
110	 * Set dma_ops to drm_device just one time.
111	 *
112	 * The dma mapping api needs device object and the api is used
113	 * to allocate physial memory and map it with iommu table.
114	 * If iommu attach succeeded, the sub driver would have dma_ops
115	 * for iommu and also all sub drivers have same dma_ops.
116	 */
117	if (!dev->archdata.dma_ops)
118		dev->archdata.dma_ops = subdrv_dev->archdata.dma_ops;
119
120	return 0;
121}
122
123/*
124 * drm_iommu_detach_device -detach device address space mapping from device
125 *
126 * @drm_dev: DRM device
127 * @subdrv_dev: device to be detached
128 *
129 * This function should be called by sub drivers to detach it from iommu
130 * mapping
131 */
132void drm_iommu_detach_device(struct drm_device *drm_dev,
133				struct device *subdrv_dev)
134{
135	struct device *dev = drm_dev->dev;
136	struct dma_iommu_mapping *mapping = dev->archdata.mapping;
137
138	if (!mapping || !mapping->domain)
139		return;
140
141	iommu_detach_device(mapping->domain, subdrv_dev);
142	drm_release_iommu_mapping(drm_dev);
143}