Commit a5bf3cfc authored by Thierry Reding's avatar Thierry Reding Committed by Joerg Roedel
Browse files

iommu: Implement of_iommu_get_resv_regions() 



This is an implementation that IOMMU drivers can use to obtain reserved
memory regions from a device tree node. It uses the reserved-memory DT
bindings to find the regions associated with a given device. If these
regions are marked accordingly, identity mappings will be created for
them in the IOMMU domain that the devices will be attached to.

Cc: Frank Rowand <frowand.list@gmail.com>
Cc: devicetree@vger.kernel.org
Reviewed-by: default avatarRob Herring <robh@kernel.org>
Acked-by: default avatarRobin Murphy <robin.murphy@arm.com>
Signed-off-by: default avatarThierry Reding <treding@nvidia.com>
Link: https://lore.kernel.org/r/20230120174251.4004100-4-thierry.reding@gmail.com


Signed-off-by: default avatarJoerg Roedel <jroedel@suse.de>
parent af0d8135

drivers/iommu/of_iommu.c

+94 −0
Original line number Diff line number Diff line
@@ -10,6 +10,7 @@ 
#include <linux/limits.h>

#include <linux/module.h>

#include <linux/of.h>

#include <linux/of_address.h>

#include <linux/of_iommu.h>

#include <linux/of_pci.h>

#include <linux/pci.h>
@@ -171,3 +172,96 @@ const struct iommu_ops *of_iommu_configure(struct device *dev, 


	return ops;

}



static enum iommu_resv_type iommu_resv_region_get_type(struct device *dev, struct resource *phys,

						       phys_addr_t start, size_t length)

{

	phys_addr_t end = start + length - 1;



	/*

	 * IOMMU regions without an associated physical region cannot be

	 * mapped and are simply reservations.

	 */

	if (phys->start >= phys->end)

		return IOMMU_RESV_RESERVED;



	/* may be IOMMU_RESV_DIRECT_RELAXABLE for certain cases */

	if (start == phys->start && end == phys->end)

		return IOMMU_RESV_DIRECT;



	dev_warn(dev, "treating non-direct mapping [%pr] -> [%pap-%pap] as reservation\n", &phys,

		 &start, &end);

	return IOMMU_RESV_RESERVED;

}



/**

 * of_iommu_get_resv_regions - reserved region driver helper for device tree

 * @dev: device for which to get reserved regions

 * @list: reserved region list

 *

 * IOMMU drivers can use this to implement their .get_resv_regions() callback

 * for memory regions attached to a device tree node. See the reserved-memory

 * device tree bindings on how to use these:

 *

 *   Documentation/devicetree/bindings/reserved-memory/reserved-memory.txt

 */

void of_iommu_get_resv_regions(struct device *dev, struct list_head *list)

{

#if IS_ENABLED(CONFIG_OF_ADDRESS)

	struct of_phandle_iterator it;

	int err;



	of_for_each_phandle(&it, err, dev->of_node, "memory-region", NULL, 0) {

		const __be32 *maps, *end;

		struct resource phys;

		int size;



		memset(&phys, 0, sizeof(phys));



		/*

		 * The "reg" property is optional and can be omitted by reserved-memory regions

		 * that represent reservations in the IOVA space, which are regions that should

		 * not be mapped.

		 */

		if (of_find_property(it.node, "reg", NULL)) {

			err = of_address_to_resource(it.node, 0, &phys);

			if (err < 0) {

				dev_err(dev, "failed to parse memory region %pOF: %d\n",

					it.node, err);

				continue;

			}

		}



		maps = of_get_property(it.node, "iommu-addresses", &size);

		if (!maps)

			continue;



		end = maps + size / sizeof(__be32);



		while (maps < end) {

			struct device_node *np;

			u32 phandle;



			phandle = be32_to_cpup(maps++);

			np = of_find_node_by_phandle(phandle);



			if (np == dev->of_node) {

				int prot = IOMMU_READ | IOMMU_WRITE;

				struct iommu_resv_region *region;

				enum iommu_resv_type type;

				phys_addr_t iova;

				size_t length;



				maps = of_translate_dma_region(np, maps, &iova, &length);

				type = iommu_resv_region_get_type(dev, &phys, iova, length);



				region = iommu_alloc_resv_region(iova, length, prot, type,

								 GFP_KERNEL);

				if (region)

					list_add_tail(&region->list, list);

			}

		}

	}

#endif

}

EXPORT_SYMBOL(of_iommu_get_resv_regions);

include/linux/of_iommu.h

+8 −0
Original line number Diff line number Diff line
@@ -12,6 +12,9 @@ extern const struct iommu_ops *of_iommu_configure(struct device *dev, 
					struct device_node *master_np,

					const u32 *id);



extern void of_iommu_get_resv_regions(struct device *dev,

				      struct list_head *list);



#else



static inline const struct iommu_ops *of_iommu_configure(struct device *dev,
@@ -21,6 +24,11 @@ static inline const struct iommu_ops *of_iommu_configure(struct device *dev, 
	return NULL;

}



static inline void of_iommu_get_resv_regions(struct device *dev,

					     struct list_head *list)

{

}



#endif	/* CONFIG_OF_IOMMU */



#endif /* __OF_IOMMU_H */