[PATCH v5 2/8] 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. Also introduce a union to struct
iommu_resv_region to hold any firmware specific data(eg:RMR
specific info).

Signed-off-by: Shameer Kolothum <shameerali.kolothum.thodi at huawei.com>
---
 drivers/iommu/dma-iommu.c | 29 +++++++++++++++++++++++++++++
 include/linux/dma-iommu.h | 13 +++++++++++++
 include/linux/iommu.h     | 10 ++++++++++
 3 files changed, 52 insertions(+)

diff --git a/drivers/iommu/dma-iommu.c b/drivers/iommu/dma-iommu.c
index 7bcdd1205535..229ec65d98be 100644
--- a/drivers/iommu/dma-iommu.c
+++ b/drivers/iommu/dma-iommu.c
@@ -174,6 +174,35 @@ void iommu_put_dma_cookie(struct iommu_domain *domain)
 }
 EXPORT_SYMBOL(iommu_put_dma_cookie);
 
+/**
+ *
+ * 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 -EINVAL;
+}
+EXPORT_SYMBOL(iommu_dma_get_rmrs);
+
+/**
+ *
+ * iommu_dma_put_rmrs - Release Reserved Memory Regions(RMRs) associated
+ *                      with a given IOMMU
+ * @iommu_fwnode: fwnode associated with IOMMU
+ * @list: RMR list
+ *
+ */
+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 6e75a2d689b4..a83e6c09444c 100644
--- a/include/linux/dma-iommu.h
+++ b/include/linux/dma-iommu.h
@@ -42,12 +42,16 @@ void iommu_dma_free_cpu_cached_iovas(unsigned int cpu,
 
 extern bool iommu_dma_forcedac;
 
+int iommu_dma_get_rmrs(struct fwnode_handle *iommu, 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 size)
@@ -83,5 +87,14 @@ static inline void iommu_dma_get_resv_regions(struct device *dev, struct list_he
 {
 }
 
+int iommu_dma_get_rmrs(struct fwnode_handle *iommu, struct list_head *list)
+{
+	return -ENODEV;
+}
+
+void iommu_dma_put_rmrs(struct fwnode_handle *iommu, struct list_head *list)
+{
+}
+
 #endif	/* CONFIG_IOMMU_DMA */
 #endif	/* __DMA_IOMMU_H */
diff --git a/include/linux/iommu.h b/include/linux/iommu.h
index 32d448050bf7..856a1736c744 100644
--- a/include/linux/iommu.h
+++ b/include/linux/iommu.h
@@ -114,6 +114,12 @@ enum iommu_resv_type {
 	IOMMU_RESV_SW_MSI,
 };
 
+struct iommu_iort_rmr_data {
+#define IOMMU_RMR_REMAP_PERMITTED	(1 << 0)
+	u32 flags;
+	u32 sid;	/* Stream Id associated with RMR entry */
+};
+
 /**
  * struct iommu_resv_region - descriptor for a reserved memory region
  * @list: Linked list pointers
@@ -121,6 +127,7 @@ enum iommu_resv_type {
  * @length: Length of the region in bytes
  * @prot: IOMMU Protection flags (READ/WRITE/...)
  * @type: Type of the reserved region
+ * @rmr: ACPI IORT RMR specific data
  */
 struct iommu_resv_region {
 	struct list_head	list;
@@ -128,6 +135,9 @@ struct iommu_resv_region {
 	size_t			length;
 	int			prot;
 	enum iommu_resv_type	type;
+	union {
+		struct iommu_iort_rmr_data rmr;
+	} fw_data;
 };
 
 /**
-- 
2.17.1