ACPI/IORT: Provide a generic helper to retrieve reserve regions

Currently IORT provides a helper to retrieve HW MSI reserve regions.
Change this to a generic helper to retrieve any IORT related reserve
regions. This will be useful when we add support for RMR nodes in
subsequent patches.

[Lorenzo: For ACPI IORT]
Reviewed-by: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Tested-by: Steven Price <steven.price@arm.com>
Tested-by: Laurentiu Tudor <laurentiu.tudor@nxp.com>
Tested-by: Hanjun Guo <guohanjun@huawei.com>
Reviewed-by: Hanjun Guo <guohanjun@huawei.com>
Signed-off-by: Shameer Kolothum <shameerali.kolothum.thodi@huawei.com>
Acked-by: Robin Murphy <robin.murphy@arm.com>
Link: https://lore.kernel.org/r/20220615101044.1972-4-shameerali.kolothum.thodi@huawei.comSigned-off-by: Joerg Roedel <jroedel@suse.de>

drivers/acpi/arm64/iort.c

@@ -806,15 +806,13 @@ static struct acpi_iort_node *iort_get_msi_resv_iommu(struct device *dev)
 	return NULL;
 }
 
-/**
- * iort_iommu_msi_get_resv_regions - Reserved region driver helper
- * @dev: Device from iommu_get_resv_regions()
- * @head: Reserved region list from iommu_get_resv_regions()
- *
+/*
+ * Retrieve platform specific HW MSI reserve regions.
  * The ITS interrupt translation spaces (ITS_base + SZ_64K, SZ_64K)
  * associated with the device are the HW MSI reserved regions.
  */
-void iort_iommu_msi_get_resv_regions(struct device *dev, struct list_head *head)
+static void iort_iommu_msi_get_resv_regions(struct device *dev,
+					    struct list_head *head)
 {
 	struct iommu_fwspec *fwspec = dev_iommu_fwspec_get(dev);
 	struct acpi_iort_its_group *its;
@@ -863,6 +861,16 @@ void iort_iommu_msi_get_resv_regions(struct device *dev, struct list_head *head)
 	}
 }
 
+/**
+ * iort_iommu_get_resv_regions - Generic helper to retrieve reserved regions.
+ * @dev: Device from iommu_get_resv_regions()
+ * @head: Reserved region list from iommu_get_resv_regions()
+ */
+void iort_iommu_get_resv_regions(struct device *dev, struct list_head *head)
+{
+	iort_iommu_msi_get_resv_regions(dev, head);
+}
+
 static inline bool iort_iommu_driver_enabled(u8 type)
 {
 	switch (type) {
@@ -1027,7 +1035,7 @@ int iort_iommu_configure_id(struct device *dev, const u32 *id_in)
 }
 
 #else
-void iort_iommu_msi_get_resv_regions(struct device *dev, struct list_head *head)
+void iort_iommu_get_resv_regions(struct device *dev, struct list_head *head)
 { }
 int iort_iommu_configure_id(struct device *dev, const u32 *input_id)
 { return -ENODEV; }

drivers/iommu/dma-iommu.c

@@ -387,7 +387,7 @@ void iommu_dma_get_resv_regions(struct device *dev, struct list_head *list)
 {
 
 	if (!is_of_node(dev_iommu_fwspec_get(dev)->iommu_fwnode))
-		iort_iommu_msi_get_resv_regions(dev, list);
+		iort_iommu_get_resv_regions(dev, list);
 
 }
 EXPORT_SYMBOL(iommu_dma_get_resv_regions);

include/linux/acpi_iort.h

@@ -36,7 +36,7 @@ int iort_pmsi_get_dev_id(struct device *dev, u32 *dev_id);
 /* IOMMU interface */
 int iort_dma_get_ranges(struct device *dev, u64 *size);
 int iort_iommu_configure_id(struct device *dev, const u32 *id_in);
-void iort_iommu_msi_get_resv_regions(struct device *dev, struct list_head *head);
+void iort_iommu_get_resv_regions(struct device *dev, struct list_head *head);
 phys_addr_t acpi_iort_dma_get_max_cpu_address(void);
 #else
 static inline void acpi_iort_init(void) { }
@@ -52,7 +52,7 @@ static inline int iort_dma_get_ranges(struct device *dev, u64 *size)
 static inline int iort_iommu_configure_id(struct device *dev, const u32 *id_in)
 { return -ENODEV; }
 static inline
-void iort_iommu_msi_get_resv_regions(struct device *dev, struct list_head *head)
+void iort_iommu_get_resv_regions(struct device *dev, struct list_head *head)
 { }
 
 static inline phys_addr_t acpi_iort_dma_get_max_cpu_address(void)