From: Thierry Reding <treding@xxxxxxxxxx> 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@xxxxxxxxx> Cc: devicetree@xxxxxxxxxxxxxxx Reviewed-by: Rob Herring <robh@xxxxxxxxxx> Signed-off-by: Thierry Reding <treding@xxxxxxxxxx> --- Rob, I've dropped your Reviewed-by: for now since there were some significant changes since you looked at this. Please take another look to confirm that it still applies. Changes in v10: - extract more code into the new iommu_resv_region_get_type() function - rename variables for physical and I/O virtual addresses for clarity - default to IOMMU_RESV_DIRECT instead of IOMMU_RESV_DIRECT_RELAXABLE - use newly introduced of_translate_dma_region() Changes in v9: - address review comments by Robin Murphy: - warn about non-direct mappings since they are not supported yet - cleanup code to require less indentation - narrow scope of variables Changes in v8: - cleanup set-but-unused variables Changes in v6: - remove reference to now unused dt-bindings/reserved-memory.h include Changes in v5: - update for new "iommu-addresses" device tree bindings Changes in v4: - fix build failure on !CONFIG_OF_ADDRESS Changes in v3: - change "active" property to identity mapping flag that is part of the memory region specifier (as defined by #memory-region-cells) to allow per-reference flags to be used Changes in v2: - use "active" property to determine whether direct mappings are needed --- drivers/iommu/of_iommu.c | 94 ++++++++++++++++++++++++++++++++++++++++ include/linux/of_iommu.h | 8 ++++ 2 files changed, 102 insertions(+) diff --git a/drivers/iommu/of_iommu.c b/drivers/iommu/of_iommu.c index 5696314ae69e..fa7c63a4abbf 100644 --- a/drivers/iommu/of_iommu.c +++ b/drivers/iommu/of_iommu.c @@ -11,6 +11,7 @@ #include <linux/module.h> #include <linux/msi.h> #include <linux/of.h> +#include <linux/of_address.h> #include <linux/of_iommu.h> #include <linux/of_pci.h> #include <linux/pci.h> @@ -172,3 +173,96 @@ 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(®ion->list, list); + } + } + } +#endif +} +EXPORT_SYMBOL(of_iommu_get_resv_regions); diff --git a/include/linux/of_iommu.h b/include/linux/of_iommu.h index 55c1eb300a86..9a5e6b410dd2 100644 --- a/include/linux/of_iommu.h +++ b/include/linux/of_iommu.h @@ -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 */ -- 2.38.1