[RFC PATCH 05/11] docs/doxygen: Add doxygen tags to grant_table.h

[Luca Fancellu <luca.fancellu@xxxxxxx>]

Add doxygen tags to grant_table.h for:
1) Create Grant tables section
2) include variables in the generated documentation

Signed-off-by: Luca Fancellu <luca.fancellu@xxxxxxx>
---
 xen/include/public/grant_table.h | 92 ++++++++++++++++++++++++--------
 1 file changed, 70 insertions(+), 22 deletions(-)

diff --git a/xen/include/public/grant_table.h b/xen/include/public/grant_table.h
index 3b7bf93d74..19ab362d80 100644
--- a/xen/include/public/grant_table.h
+++ b/xen/include/public/grant_table.h
@@ -25,6 +25,12 @@
  * Copyright (c) 2004, K A Fraser
  */
 
+/**
+ * @file
+ * @brief Interface for granting foreign access to page frames, and receiving
+ * page-ownership transfers.
+ */
+
 #ifndef __XEN_PUBLIC_GRANT_TABLE_H__
 #define __XEN_PUBLIC_GRANT_TABLE_H__
 
@@ -32,8 +38,10 @@
 
 /*
  * `incontents 150 gnttab Grant Tables
- *
- * Xen's grant tables provide a generic mechanism to memory sharing
+ */
+
+/**
+ * @brief Xen's grant tables provide a generic mechanism to memory sharing
  * between domains. This shared memory interface underpins the split
  * device drivers for block and network IO.
  *
@@ -51,13 +59,10 @@
  * know the real machine address of a page it is sharing. This makes
  * it possible to share memory correctly with domains running in
  * fully virtualised memory.
- */
-
-/***********************************
+ *
  * GRANT TABLE REPRESENTATION
- */
-
-/* Some rough guidelines on accessing and updating grant-table entries
+ *
+ * Some rough guidelines on accessing and updating grant-table entries
  * in a concurrency-safe manner. For more information, Linux contains a
  * reference implementation for guest OSes (drivers/xen/grant_table.c, see
  * 
http://git.kernel.org/?p=linux/kernel/git/torvalds/linux.git;a=blob;f=drivers/xen/grant-table.c;hb=HEAD
@@ -66,6 +71,7 @@
  *     compiler barrier will still be required.
  *
  * Introducing a valid entry into the grant table:
+ * @code
  *  1. Write ent->domid.
  *  2. Write ent->frame:
  *      GTF_permit_access:   Frame to which access is permitted.
@@ -73,20 +79,25 @@
  *                           frame, or zero if none.
  *  3. Write memory barrier (WMB).
  *  4. Write ent->flags, inc. valid type.
+ * @endcode
  *
  * Invalidating an unused GTF_permit_access entry:
+ * @code
  *  1. flags = ent->flags.
  *  2. Observe that !(flags & (GTF_reading|GTF_writing)).
  *  3. Check result of SMP-safe CMPXCHG(&ent->flags, flags, 0).
  *  NB. No need for WMB as reuse of entry is control-dependent on success of
  *      step 3, and all architectures guarantee ordering of ctrl-dep writes.
+ * @endcode
  *
  * Invalidating an in-use GTF_permit_access entry:
+ *
  *  This cannot be done directly. Request assistance from the domain controller
  *  which can set a timeout on the use of a grant entry and take necessary
  *  action. (NB. This is not yet implemented!).
  *
  * Invalidating an unused GTF_accept_transfer entry:
+ * @code
  *  1. flags = ent->flags.
  *  2. Observe that !(flags & GTF_transfer_committed). [*]
  *  3. Check result of SMP-safe CMPXCHG(&ent->flags, flags, 0).
@@ -97,47 +108,55 @@
  *      transferred frame is written. It is safe for the guest to spin waiting
  *      for this to occur (detect by observing GTF_transfer_completed in
  *      ent->flags).
+ * @endcode
  *
  * Invalidating a committed GTF_accept_transfer entry:
  *  1. Wait for (ent->flags & GTF_transfer_completed).
  *
  * Changing a GTF_permit_access from writable to read-only:
+ *
  *  Use SMP-safe CMPXCHG to set GTF_readonly, while checking !GTF_writing.
  *
  * Changing a GTF_permit_access from read-only to writable:
+ *
  *  Use SMP-safe bit-setting instruction.
- */
-
-/*
- * Reference to a grant entry in a specified domain's grant table.
- */
-typedef uint32_t grant_ref_t;
-
-/*
+ *
  * A grant table comprises a packed array of grant entries in one or more
  * page frames shared between Xen and a guest.
+ *
  * [XEN]: This field is written by Xen and read by the sharing guest.
+ *
  * [GST]: This field is written by the guest and read by Xen.
+ *
+ * @addtogroup grant_table Grant Tables
+ * @{
  */
 
-/*
- * Version 1 of the grant table entry structure is maintained purely
- * for backwards compatibility.  New guests should use version 2.
+/**
+ * Reference to a grant entry in a specified domain's grant table.
  */
+typedef uint32_t grant_ref_t;
+
 #if __XEN_INTERFACE_VERSION__ < 0x0003020a
 #define grant_entry_v1 grant_entry
 #define grant_entry_v1_t grant_entry_t
 #endif
+/**
+ * Version 1 of the grant table entry structure is maintained purely
+ * for backwards compatibility.  New guests should use version 2.
+ */
 struct grant_entry_v1 {
-    /* GTF_xxx: various type and flag information.  [XEN,GST] */
+    /** GTF_xxx: various type and flag information.  [XEN,GST] */
     uint16_t flags;
-    /* The domain being granted foreign privileges. [GST] */
+    /** The domain being granted foreign privileges. [GST] */
     domid_t  domid;
-    /*
+    /**
+     * @code
      * GTF_permit_access: GFN that @domid is allowed to map and access. [GST]
      * GTF_accept_transfer: GFN that @domid is allowed to transfer into. [GST]
      * GTF_transfer_completed: MFN whose ownership transferred by @domid
      *                         (non-translated guests only). [XEN]
+     * @endcode
      */
     uint32_t frame;
 };
@@ -241,7 +260,12 @@ union grant_entry_v2 {
      * In that case, the frame field has the same semantics as the
      * field of the same name in the V1 entry structure.
      */
+#ifdef DOXYGEN
+    /* Workaround: Doxygen cannot handle anonymous union/struct */
+    struct full_page {
+#else
     struct {
+#endif
         grant_entry_header_t hdr;
         uint32_t pad0;
         uint64_t frame;
@@ -252,7 +276,12 @@ union grant_entry_v2 {
      * @domid is allowed to access bytes [@page_off,@page_off+@length)
      * in frame @frame.
      */
+#ifdef DOXYGEN
+    /* Workaround: Doxygen cannot handle anonymous union/struct */
+    struct sub_page {
+#else
     struct {
+#endif
         grant_entry_header_t hdr;
         uint16_t page_off;
         uint16_t length;
@@ -268,7 +297,12 @@ union grant_entry_v2 {
      * The current version of Xen does not allow transitive grants
      * to be mapped.
      */
+#ifdef DOXYGEN
+    /* Workaround: Doxygen cannot handle anonymous union/struct */
+    struct transitive {
+#else
     struct {
+#endif
         grant_entry_header_t hdr;
         domid_t trans_domid;
         uint16_t pad0;
@@ -457,7 +491,12 @@ DEFINE_XEN_GUEST_HANDLE(gnttab_transfer_t);
 struct gnttab_copy {
     /* IN parameters. */
     struct gnttab_copy_ptr {
+#ifdef DOXYGEN
+        /* Workaround: Doxygen cannot handle anonymous union/struct */
+        union u {
+#else
         union {
+#endif
             grant_ref_t ref;
             xen_pfn_t   gmfn;
         } u;
@@ -582,7 +621,12 @@ DEFINE_XEN_GUEST_HANDLE(gnttab_swap_grant_ref_t);
  * page granted to the calling domain by a foreign domain.
  */
 struct gnttab_cache_flush {
+#ifdef DOXYGEN
+    /* Workaround: Doxygen cannot handle anonymous union/struct */
+    union a {
+#else
     union {
+#endif
         uint64_t dev_bus_addr;
         grant_ref_t ref;
     } a;
@@ -671,6 +715,10 @@ DEFINE_XEN_GUEST_HANDLE(gnttab_cache_flush_t);
     "operation not done; try again"             \
 }
 
+/**
+ * @}
+*/
+
 #endif /* __XEN_PUBLIC_GRANT_TABLE_H__ */
 
 /*
-- 
2.17.1