Opaque virtual address type

This ensures that conversions and arithmetic on virtual addresses are
explicit and not accidental due to it being a primitive integer.

Change-Id: I94dd8e82e065757ae448d98be0cb89eaa1f6542d
diff --git a/inc/mm.h b/inc/mm.h
index 31f5c2f..1e00310 100644
--- a/inc/mm.h
+++ b/inc/mm.h
@@ -7,10 +7,15 @@
 #include "arch_mm.h"
 
 struct mm_ptable {
-	pte_t *table;
+	paddr_t table;
 	uint32_t id;
 };
 
+/* An opaque type for an intermediate physical address from a VM. */
+typedef struct {
+	uintpaddr_t ipa;
+} ipaddr_t;
+
 #define PAGE_SIZE (1 << PAGE_BITS)
 
 /* The following are arch-independent page mapping modes. */
@@ -55,4 +60,68 @@
 bool mm_unmap(vaddr_t begin, vaddr_t end, int mode);
 void mm_defrag(void);
 
+/**
+ * Initializes an intermeditate physical address.
+ */
+static inline ipaddr_t ipa_init(uintvaddr_t v)
+{
+	return (ipaddr_t){.ipa = v};
+}
+
+/**
+ * Extracts the absolute intermediate physical address.
+ */
+static inline uintpaddr_t ipa_addr(ipaddr_t ipa)
+{
+	return ipa.ipa;
+}
+
+/**
+ * Converts a physical address to a virtual address. Addresses are currently
+ * identity mapped so this is a simple type convertion.
+ */
+static inline vaddr_t mm_va_from_pa(paddr_t pa)
+{
+	return va_init(pa_addr(pa));
+}
+
+/**
+ * Converts a virtual address to a physical address. Addresses are currently
+ * identity mapped so this is a simple type convertion.
+ */
+static inline paddr_t mm_pa_from_va(vaddr_t va)
+{
+	return pa_init(va_addr(va));
+}
+
+/**
+ * Converts an intermediate physical address to a physical address. Addresses
+ * are currently identity mapped so this is a simple type convertion. Returns
+ * true if the address was mapped in the table and the address was converted.
+ */
+static inline bool mm_pa_from_ipa(struct mm_ptable *t, ipaddr_t ipa,
+				  paddr_t *pa)
+{
+	/* TODO: the ptable functions map physical to virtual addresses but they
+	 * should really be mapping to intermediate physical addresses.
+	 * It might be better to have different interfaces to the mm functions?
+	 * This might also mean ipaddr_t should be used when building the VM
+	 * tables too?
+	 * */
+	if (mm_ptable_is_mapped(t, va_init(ipa_addr(ipa)), 0)) {
+		*pa = pa_init(ipa_addr(ipa));
+		return true;
+	}
+	return false;
+}
+
+/**
+ * Converts a virtual address to a pointer. Only use when the virtual address
+ * is mapped for the calling context.
+ */
+static inline void *mm_ptr_from_va(vaddr_t va)
+{
+	return (void *)va_addr(va);
+}
+
 #endif /* _MM_H */