[PATCH v8 04/11] iommu/dma: Introduce generic helper to retrieve RMR info

[Shameer Kolothum]

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

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

Signed-off-by: Shameer Kolothum <shameerali.kolothum.thodi at huawei.com>
---
 drivers/iommu/dma-iommu.c | 21 +++++++++++++++++++++
 include/linux/dma-iommu.h | 14 ++++++++++++++
 2 files changed, 35 insertions(+)

diff --git a/drivers/iommu/dma-iommu.c b/drivers/iommu/dma-iommu.c
index d85d54f2b549..65ab01d5128b 100644
--- a/drivers/iommu/dma-iommu.c
+++ b/drivers/iommu/dma-iommu.c
@@ -370,6 +370,27 @@ void iommu_put_dma_cookie(struct iommu_domain *domain)
 	domain->iova_cookie = NULL;
 }
 
+/**
+ *
+ * iommu_dma_get_rmrs - Retrieve Reserved Memory Regions(RMRs) associated
+ *                      with a given IOMMU and device(optional)
+ * @iommu_fwnode: fwnode associated with IOMMU
+ * @dev: Optional associated device
+ * @list: Reserved region list to be populated
+ *
+ */
+void iommu_dma_get_rmrs(struct fwnode_handle *iommu_fwnode, struct device *dev,
+			struct list_head *list)
+{
+}
+EXPORT_SYMBOL(iommu_dma_get_rmrs);
+
+void iommu_dma_put_rmrs(struct fwnode_handle *iommu_fwnode,
+			struct list_head *list)
+{
+}
+EXPORT_SYMBOL(iommu_dma_put_rmrs);
+
 /**
  * iommu_dma_get_resv_regions - Reserved region driver helper
  * @dev: Device from iommu_get_resv_regions()
diff --git a/include/linux/dma-iommu.h b/include/linux/dma-iommu.h
index 24607dc3c2ac..897b457cad2c 100644
--- a/include/linux/dma-iommu.h
+++ b/include/linux/dma-iommu.h
@@ -43,12 +43,17 @@ void iommu_dma_free_cpu_cached_iovas(unsigned int cpu,
 
 extern bool iommu_dma_forcedac;
 
+void iommu_dma_get_rmrs(struct fwnode_handle *iommu, struct device *dev,
+			struct list_head *list);
+
+void iommu_dma_put_rmrs(struct fwnode_handle *iommu, struct list_head *list);
 #else /* CONFIG_IOMMU_DMA */
 
 struct iommu_domain;
 struct msi_desc;
 struct msi_msg;
 struct device;
+struct fwnode_handle;
 
 static inline void iommu_setup_dma_ops(struct device *dev, u64 dma_base,
 				       u64 dma_limit)
@@ -89,5 +94,14 @@ static inline void iommu_dma_get_resv_regions(struct device *dev, struct list_he
 {
 }
 
+static inline void iommu_dma_get_rmrs(struct fwnode_handle *iommu, struct device *dev,
+				      struct list_head *list)
+{
+}
+
+static inline void iommu_dma_put_rmrs(struct fwnode_handle *iommu, struct list_head *list)
+{
+}
+
 #endif	/* CONFIG_IOMMU_DMA */
 #endif	/* __DMA_IOMMU_H */
-- 
2.25.1