1 files changed, 143 insertions, 0 deletions
diff --git a/drivers/gpu/drm/exynos/exynos_drm_dma.c b/drivers/gpu/drm/exynos/exynos_drm_dma.c
new file mode 100644
index 000000000..e2c7373f2
--- /dev/null
+++ b/drivers/gpu/drm/exynos/exynos_drm_dma.c
@@ -0,0 +1,143 @@
+// 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(&platform_bus_type,
+				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;
+}