drm/exynos: iommu: add support for ARM64 specific code for IOMMU glue

This patch adds support for ARM 64bit architecture with IOMMU-DMA glue
code, so Exynos DRM can be now used on Exynos 5433 with IOMMU enabled.
Signed-off-by: Marek Szyprowski <m.szyprowski@samsung.com>
Signed-off-by: Inki Dae <inki.dae@samsung.com>

drivers/gpu/drm/exynos/Kconfig

@@ -15,7 +15,7 @@ if DRM_EXYNOS
 
 config DRM_EXYNOS_IOMMU
 	bool
-	depends on EXYNOS_IOMMU && ARM_DMA_USE_IOMMU
+	depends on EXYNOS_IOMMU
 	default y
 
 comment "CRTCs"

drivers/gpu/drm/exynos/exynos_drm_drv.c

@@ -159,12 +159,7 @@ static int exynos_drm_load(struct drm_device *dev, unsigned long flags)
 	DRM_INFO("Exynos DRM: using %s device for DMA mapping operations\n",
 		 dev_name(private->dma_dev));
 
-	/*
-	 * create mapping to manage iommu table and set a pointer to iommu
-	 * mapping structure to iommu_mapping of private data.
-	 * also this iommu_mapping can be used to check if iommu is supported
-	 * or not.
-	 */
+	/* create common IOMMU mapping for all devices attached to Exynos DRM */
 	ret = drm_create_iommu_mapping(dev);
 	if (ret < 0) {
 		DRM_ERROR("failed to create iommu mapping.\n");

drivers/gpu/drm/exynos/exynos_drm_iommu.h

@@ -49,6 +49,61 @@ static inline void __exynos_iommu_detach(struct exynos_drm_private *priv,
 	arm_iommu_detach_device(dev);
 }
 
+#elif defined(CONFIG_IOMMU_DMA)
+#include <linux/dma-iommu.h>
+
+static inline int __exynos_iommu_create_mapping(struct exynos_drm_private *priv,
+					unsigned long start, unsigned long size)
+{
+	struct iommu_domain *domain;
+	int ret;
+
+	domain = iommu_domain_alloc(priv->dma_dev->bus);
+	if (!domain)
+		return -ENOMEM;
+
+	ret = iommu_get_dma_cookie(domain);
+	if (ret)
+		goto free_domain;
+
+	ret = iommu_dma_init_domain(domain, start, size);
+	if (ret)
+		goto put_cookie;
+
+	priv->mapping = domain;
+	return 0;
+
+put_cookie:
+	iommu_put_dma_cookie(domain);
+free_domain:
+	iommu_domain_free(domain);
+	return ret;
+}
+
+static inline void __exynos_iommu_release_mapping(struct exynos_drm_private *priv)
+{
+	struct iommu_domain *domain = priv->mapping;
+
+	iommu_put_dma_cookie(domain);
+	iommu_domain_free(domain);
+	priv->mapping = NULL;
+}
+
+static inline int __exynos_iommu_attach(struct exynos_drm_private *priv,
+					struct device *dev)
+{
+	struct iommu_domain *domain = priv->mapping;
+
+	return iommu_attach_device(domain, dev);
+}
+
+static inline void __exynos_iommu_detach(struct exynos_drm_private *priv,
+					 struct device *dev)
+{
+	struct iommu_domain *domain = priv->mapping;
+
+	iommu_detach_device(domain, dev);
+}
 #else
 #error Unsupported architecture and IOMMU/DMA-mapping glue code
 #endif