From dd6b68ed4f5bba78c0cd9765fa48b10cb1542dc7 Mon Sep 17 00:00:00 2001
From: Mark Kettenis <kettenis@openbsd.org>
Date: Sat, 21 Jan 2023 20:27:52 +0100
Subject: [PATCH] iommu: Add DMA mapping operations

In order to support IOMMUs in non-bypass mode we need device ops
to map and unmap DMA memory.  The map operation enters a mapping
for a region specified by CPU address and size into the translation
table of the IOMMU and returns a DMA address suitable for
programming the device to do DMA.  The unmap operation removes
this mapping from the translation table of the IOMMU.

Signed-off-by: Mark Kettenis <kettenis@openbsd.org>
---
 drivers/iommu/iommu-uclass.c | 28 ++++++++++++++++++++++++++++
 include/dm/device.h          |  4 ++++
 include/iommu.h              | 24 ++++++++++++++++++++++++
 3 files changed, 56 insertions(+)

diff --git a/drivers/iommu/iommu-uclass.c b/drivers/iommu/iommu-uclass.c
index ed917b3c3e..f6b1457736 100644
--- a/drivers/iommu/iommu-uclass.c
+++ b/drivers/iommu/iommu-uclass.c
@@ -7,6 +7,9 @@
 
 #include <common.h>
 #include <dm.h>
+#include <iommu.h>
+#include <phys2bus.h>
+#include <asm/io.h>
 
 #if (CONFIG_IS_ENABLED(OF_CONTROL) && !CONFIG_IS_ENABLED(OF_PLATDATA))
 int dev_iommu_enable(struct udevice *dev)
@@ -33,12 +36,37 @@ int dev_iommu_enable(struct udevice *dev)
 			      __func__, ret);
 			return ret;
 		}
+		dev->iommu = dev_iommu;
 	}
 
 	return 0;
 }
 #endif
 
+dma_addr_t dev_iommu_dma_map(struct udevice *dev, void *addr, size_t size)
+{
+	const struct iommu_ops *ops;
+
+	if (dev->iommu) {
+		ops = device_get_ops(dev->iommu);
+		if (ops && ops->map)
+			return ops->map(dev->iommu, addr, size);
+	}
+
+	return dev_phys_to_bus(dev, virt_to_phys(addr));
+}
+
+void dev_iommu_dma_unmap(struct udevice *dev, dma_addr_t addr, size_t size)
+{
+	const struct iommu_ops *ops;
+
+	if (dev->iommu) {
+		ops = device_get_ops(dev->iommu);
+		if (ops && ops->unmap)
+			ops->unmap(dev->iommu, addr, size);
+	}
+}
+
 UCLASS_DRIVER(iommu) = {
 	.id		= UCLASS_IOMMU,
 	.name		= "iommu",
diff --git a/include/dm/device.h b/include/dm/device.h
index f3f953c9af..e9460386ca 100644
--- a/include/dm/device.h
+++ b/include/dm/device.h
@@ -165,6 +165,7 @@ enum {
  *		automatically when the device is removed / unbound
  * @dma_offset: Offset between the physical address space (CPU's) and the
  *		device's bus address space
+ * @iommu: IOMMU device associated with this device
  */
 struct udevice {
 	const struct driver *driver;
@@ -194,6 +195,9 @@ struct udevice {
 #if CONFIG_IS_ENABLED(DM_DMA)
 	ulong dma_offset;
 #endif
+#if CONFIG_IS_ENABLED(IOMMU)
+	struct udevice *iommu;
+#endif
 };
 
 static inline int dm_udevice_size(void)
diff --git a/include/iommu.h b/include/iommu.h
index 6c46adf449..cf9719c5e9 100644
--- a/include/iommu.h
+++ b/include/iommu.h
@@ -3,6 +3,27 @@
 
 struct udevice;
 
+struct iommu_ops {
+	/**
+	 * map() - map DMA memory
+	 *
+	 * @dev:	device for which to map DMA memory
+	 * @addr:	CPU address of the memory
+	 * @size:	size of the memory
+	 * @return DMA address for the device
+	 */
+	dma_addr_t (*map)(struct udevice *dev, void *addr, size_t size);
+
+	/**
+	 * unmap() - unmap DMA memory
+	 *
+	 * @dev:	device for which to unmap DMA memory
+	 * @addr:	DMA address of the memory
+	 * @size:	size of the memory
+	 */
+	void (*unmap)(struct udevice *dev, dma_addr_t addr, size_t size);
+};
+
 #if (CONFIG_IS_ENABLED(OF_CONTROL) && !CONFIG_IS_ENABLED(OF_PLATDATA)) && \
 	CONFIG_IS_ENABLED(IOMMU)
 int dev_iommu_enable(struct udevice *dev);
@@ -13,4 +34,7 @@ static inline int dev_iommu_enable(struct udevice *dev)
 }
 #endif
 
+dma_addr_t dev_iommu_dma_map(struct udevice *dev, void *addr, size_t size);
+void dev_iommu_dma_unmap(struct udevice *dev, dma_addr_t addr, size_t size);
+
 #endif
-- 
2.39.5