iommu/dma: Introduce generic helper to retrieve RMR info

Reserved Memory Regions(RMR) associated with an IOMMU may be
described either through ACPI tables or DT in systems with
devices that require a unity mapping or bypass for those
regions in IOMMU drivers.

Introduce a generic interface so that IOMMU drivers can retrieve
and set up necessary mappings.

Signed-off-by: Shameer Kolothum <shameerali.kolothum.thodi@huawei.com>

drivers/iommu/dma-iommu.c

@@ -191,6 +191,39 @@ void iommu_dma_get_resv_regions(struct device *dev, struct list_head *list)
 }
 EXPORT_SYMBOL(iommu_dma_get_resv_regions);
 
+/**
+ * iommu_dma_get_rmrs - Retrieve Reserved Memory Regions(RMRs) associated
+ *                      with a given IOMMU
+ * @iommu_fwnode: fwnode associated with IOMMU
+ * @list: RMR list to be populated
+ *
+ */
+int iommu_dma_get_rmrs(struct fwnode_handle *iommu_fwnode,
+		       struct list_head *list)
+{
+	return 0;
+}
+EXPORT_SYMBOL(iommu_dma_get_rmrs);
+
+struct iommu_rmr *iommu_dma_alloc_rmr(u64 base, u64 length, u32 sid,
+				      u32 flags)
+{
+	struct iommu_rmr *rmr;
+
+	rmr = kzalloc(sizeof(*rmr), GFP_KERNEL);
+	if (!rmr)
+		return NULL;
+
+	INIT_LIST_HEAD(&rmr->list);
+	rmr->base_address = base;
+	rmr->length = length;
+	rmr->sid = sid;
+	rmr->flags = flags;
+
+	return rmr;
+}
+EXPORT_SYMBOL(iommu_dma_alloc_rmr);
+
 static int cookie_init_hw_msi_region(struct iommu_dma_cookie *cookie,
 		phys_addr_t start, phys_addr_t end)
 {

include/linux/dma-iommu.h

@@ -40,6 +40,9 @@ void iommu_dma_get_resv_regions(struct device *dev, struct list_head *list);
 void iommu_dma_free_cpu_cached_iovas(unsigned int cpu,
 		struct iommu_domain *domain);
 
+int iommu_dma_get_rmrs(struct fwnode_handle *iommu, struct list_head *list);
+struct iommu_rmr *iommu_dma_alloc_rmr(u64 base, u64 length, u32 sid, u32 flags);
+
 #else /* CONFIG_IOMMU_DMA */
 
 struct iommu_domain;
@@ -86,5 +89,10 @@ static inline void iommu_dma_free_cpu_cached_iovas(unsigned int cpu,
 {
 }
 
+int iommu_dma_get_rmrs(struct fwnode_handle *iommu, struct list_head *list);
+{
+	return 0;
+}
+
 #endif	/* CONFIG_IOMMU_DMA */
 #endif	/* __DMA_IOMMU_H */

include/linux/iommu.h

@@ -595,6 +595,25 @@ struct iommu_sva {
 	struct device			*dev;
 };
 
+/**
+ * struct iommu_rmr - Reserved Memory Region details per IOMMU
+ * @list: Linked list pointers to hold RMR region info
+ * @base_address: base address of Reserved Memory Region
+ * @length: length of memory region
+ * @sid: associated stream id
+ * @flags: flags that apply to the RMR node
+ */
+struct iommu_rmr {
+	struct list_head	list;
+	phys_addr_t		base_address;
+	u64			length;
+	u32			sid;
+	u32			flags;
+};
+
+/* RMR Remap permitted */
+#define IOMMU_RMR_REMAP_PERMITTED	(1 << 0)
+
 int iommu_fwspec_init(struct device *dev, struct fwnode_handle *iommu_fwnode,
 		      const struct iommu_ops *ops);
 void iommu_fwspec_free(struct device *dev);