ACPI/IORT: Make iort_iommu_msi_get_resv_regions() return void

At present iort_iommu_msi_get_resv_regions() returns the number of
MSI reserved regions on success and there are no users for this.
The reserved region list will get populated anyway for platforms
that require the HW MSI region reservation. Hence, change the
function to return void instead.

Reviewed-by: Christoph Hellwig <hch@lst.de>
Tested-by: Steven Price <steven.price@arm.com>
Tested-by: Laurentiu Tudor <laurentiu.tudor@nxp.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/20220615101044.1972-3-shameerali.kolothum.thodi@huawei.com
Signed-off-by: Joerg Roedel <jroedel@suse.de>

drivers/acpi/arm64/iort.c

@@ -811,22 +811,19 @@ static struct acpi_iort_node *iort_get_msi_resv_iommu(struct device *dev)
  * @dev: Device from iommu_get_resv_regions()
  * @head: Reserved region list from iommu_get_resv_regions()
  *
- * Returns: Number of msi reserved regions on success (0 if platform
- *          doesn't require the reservation or no associated msi regions),
- *          appropriate error value otherwise. The ITS interrupt translation
- *          spaces (ITS_base + SZ_64K, SZ_64K) associated with the device
- *          are the msi reserved regions.
+ * The ITS interrupt translation spaces (ITS_base + SZ_64K, SZ_64K)
+ * associated with the device are the HW MSI reserved regions.
  */
-int iort_iommu_msi_get_resv_regions(struct device *dev, struct list_head *head)
+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;
 	struct acpi_iort_node *iommu_node, *its_node = NULL;
-	int i, resv = 0;
+	int i;
 
 	iommu_node = iort_get_msi_resv_iommu(dev);
 	if (!iommu_node)
-		return 0;
+		return;
 
 	/*
 	 * Current logic to reserve ITS regions relies on HW topologies
@@ -846,7 +843,7 @@ int iort_iommu_msi_get_resv_regions(struct device *dev, struct list_head *head)
 	}
 
 	if (!its_node)
-		return 0;
+		return;
 
 	/* Move to ITS specific data */
 	its = (struct acpi_iort_its_group *)its_node->node_data;
@@ -860,14 +857,10 @@ int iort_iommu_msi_get_resv_regions(struct device *dev, struct list_head *head)
 
 			region = iommu_alloc_resv_region(base + SZ_64K, SZ_64K,
 							 prot, IOMMU_RESV_MSI);
-			if (region) {
+			if (region)
 				list_add_tail(&region->list, head);
-				resv++;
-			}
 		}
 	}
-
-	return (resv == its->its_count) ? resv : -ENODEV;
 }
 
 static inline bool iort_iommu_driver_enabled(u8 type)
@@ -1034,8 +1027,8 @@ int iort_iommu_configure_id(struct device *dev, const u32 *id_in)
 }
 
 #else
-int iort_iommu_msi_get_resv_regions(struct device *dev, struct list_head *head)
-{ return 0; }
+void iort_iommu_msi_get_resv_regions(struct device *dev, struct list_head *head)
+{ }
 int iort_iommu_configure_id(struct device *dev, const u32 *input_id)
 { return -ENODEV; }
 #endif

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);
-int iort_iommu_msi_get_resv_regions(struct device *dev, struct list_head *head);
+void iort_iommu_msi_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) { }
@@ -52,8 +52,8 @@ 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
-int iort_iommu_msi_get_resv_regions(struct device *dev, struct list_head *head)
-{ return 0; }
+void iort_iommu_msi_get_resv_regions(struct device *dev, struct list_head *head)
+{ }
 
 static inline phys_addr_t acpi_iort_dma_get_max_cpu_address(void)
 { return PHYS_ADDR_MAX; }