iommu: Add IOMMU_RESV_TRANSLATED for non 1:1 mapped reserved regions

The display controller in Apple silicon SoCs uses bootloader mappings
which require IOMMU translation.

Signed-off-by: Janne Grunau <j@jannau.net>

Author: jannau

drivers/iommu/iommu.c

@@ -90,6 +90,7 @@ static const char * const iommu_group_resv_type_string[] = {
 	[IOMMU_RESV_RESERVED]			= "reserved",
 	[IOMMU_RESV_MSI]			= "msi",
 	[IOMMU_RESV_SW_MSI]			= "msi",
+	[IOMMU_RESV_TRANSLATED]			= "translated",
 };
 
 #define IOMMU_CMD_LINE_DMA_API		BIT(0)
@@ -2822,10 +2823,11 @@ void iommu_put_resv_regions(struct device *dev, struct list_head *list)
 }
 EXPORT_SYMBOL(iommu_put_resv_regions);
 
-struct iommu_resv_region *iommu_alloc_resv_region(phys_addr_t start,
-						  size_t length, int prot,
-						  enum iommu_resv_type type,
-						  gfp_t gfp)
+struct iommu_resv_region *iommu_alloc_resv_region_tr(phys_addr_t start,
+						     dma_addr_t dva_start,
+						     size_t length, int prot,
+						     enum iommu_resv_type type,
+						     gfp_t gfp)
 {
 	struct iommu_resv_region *region;
 
@@ -2835,11 +2837,25 @@ struct iommu_resv_region *iommu_alloc_resv_region(phys_addr_t start,
 
 	INIT_LIST_HEAD(&region->list);
 	region->start = start;
+	if (type == IOMMU_RESV_TRANSLATED)
+		region->dva = dva_start;
 	region->length = length;
 	region->prot = prot;
 	region->type = type;
 	return region;
 }
+EXPORT_SYMBOL_GPL(iommu_alloc_resv_region_tr);
+
+struct iommu_resv_region *iommu_alloc_resv_region(phys_addr_t start,
+						  size_t length, int prot,
+						  enum iommu_resv_type type,
+						  gfp_t gfp)
+{
+	if (type == IOMMU_RESV_TRANSLATED)
+		return NULL;
+
+	return iommu_alloc_resv_region_tr(start, 0, length, prot, type, gfp);
+}
 EXPORT_SYMBOL_GPL(iommu_alloc_resv_region);
 
 void iommu_set_default_passthrough(bool cmd_line)

include/linux/iommu.h

@@ -288,12 +288,18 @@ enum iommu_resv_type {
 	IOMMU_RESV_MSI,
 	/* Software-managed MSI translation window */
 	IOMMU_RESV_SW_MSI,
+	/*
+	 * Memory regions which must be mapped with the specified mapping
+	 * at all times.
+	 */
+	IOMMU_RESV_TRANSLATED,
 };
 
 /**
  * struct iommu_resv_region - descriptor for a reserved memory region
  * @list: Linked list pointers
  * @start: System physical start address of the region
+ * @start: Device virtual start address of the region for IOMMU_RESV_TRANSLATED
  * @length: Length of the region in bytes
  * @prot: IOMMU Protection flags (READ/WRITE/...)
  * @type: Type of the reserved region
@@ -302,6 +308,7 @@ enum iommu_resv_type {
 struct iommu_resv_region {
 	struct list_head	list;
 	phys_addr_t		start;
+	dma_addr_t		dva;
 	size_t			length;
 	int			prot;
 	enum iommu_resv_type	type;
@@ -892,6 +899,9 @@ extern bool iommu_default_passthrough(void);
 extern struct iommu_resv_region *
 iommu_alloc_resv_region(phys_addr_t start, size_t length, int prot,
 			enum iommu_resv_type type, gfp_t gfp);
+extern struct iommu_resv_region *
+iommu_alloc_resv_region_tr(phys_addr_t start, dma_addr_t dva_start, size_t length,
+			   int prot, enum iommu_resv_type type, gfp_t gfp);
 extern int iommu_get_group_resv_regions(struct iommu_group *group,
 					struct list_head *head);