[Pdbg] [PATCH v4 13/30] libpdbg: Child traversal should handle virtual nodes correctly

[Amitay Isaacs]

When traversing system device tree view (system == true), the children
are calculated based on the system device tree view (using the virtual
node attachments).

When traversing backend device tree (system == false), the virtual nodes
are ignored except if they are part of the backend device tree itself.

Signed-off-by: Amitay Isaacs <amitay at ozlabs.org>
---
 libpdbg/libpdbg.c | 96 ++++++++++++++++++++++++++++++++++++++++++++---
 libpdbg/libpdbg.h |  6 +--
 2 files changed, 93 insertions(+), 9 deletions(-)

diff --git a/libpdbg/libpdbg.c b/libpdbg/libpdbg.c
index aade5d3..158c63e 100644
--- a/libpdbg/libpdbg.c
+++ b/libpdbg/libpdbg.c
@@ -43,18 +43,102 @@ retry:
 	}
 }
 
-struct pdbg_target *__pdbg_next_child_target(struct pdbg_target *parent, struct pdbg_target *last)
+static struct pdbg_target *target_map_child(struct pdbg_target *next, bool system)
 {
-	if (!parent || list_empty(&parent->children))
+	/*
+	 * Map a target in system tree:
+	 *
+	 * - If there is no virtual node assiociated, then return the target
+	 *   (the target itself can be virtual or real)
+	 *
+	 * - If there is virtual node associated,
+	 *     - If the target is virtual, return the associated node
+	 *     - If the target is real, return NULL
+	 *       (this target is already covered by previous condition)
+	 *
+	 * Map a target in backend tree:
+	 *
+	 *  - If the target is real, return the target
+	 *
+	 *  - If the target is virtual, return NULL
+	 *    (no virtual nodes in backend tree)
+	 */
+	if (system) {
+		if (!next->vnode)
+			return next;
+		else
+			if (target_is_virtual(next))
+				return next->vnode;
+	} else {
+		if (!target_is_virtual(next))
+			return next;
+	}
+
+	return NULL;
+}
+
+struct pdbg_target *__pdbg_next_child_target(struct pdbg_target *parent, struct pdbg_target *last, bool system)
+{
+	struct pdbg_target *next, *child = NULL;
+
+	if (!parent)
 		return NULL;
 
-	if (!last)
-		return list_top(&parent->children, struct pdbg_target, list);
+	/*
+	 * Parent node can be virtual or real.
+	 *
+	 * If the parent node doesn't have any children,
+	 *    - If there is associated virtual node,
+	 *        Use that node as parent
+	 *
+	 *    - If there is no associated virtual node,
+	 *        No children
+	 */
+	if (list_empty(&parent->children)) {
+		if (parent->vnode)
+			parent = parent->vnode;
+		else
+			return NULL;
+	}
+
+	 /*
+	 * If the parent node has children,
+	 *    - Traverse the children
+	 *       (map the children in system or backend tree)
+	 */
+	if (!last) {
+		list_for_each(&parent->children, child, list)
+			if ((next = target_map_child(child, system)))
+				return next;
 
-	if (last->list.next == &parent->children.n)
 		return NULL;
+	}
 
-	return list_entry(last->list.next, struct pdbg_target, list);
+	/*
+	 * In a system tree traversal, virtual targets with associated
+	 * nodes, get mapped to real targets.
+	 *
+	 * When the last child is specified:
+	 *   - If in a system tree traverse, and
+	 *     the last child has associated node, and
+	 *     the last child is real
+	 *        Then the last child is not the actual child of the parent
+	 *          (the associated virtual node is the actual child)
+	 */
+	if (system)
+		last = target_to_virtual(last);
+
+	if (last == list_tail(&parent->children, struct pdbg_target, list))
+		return NULL;
+
+	child = last;
+	do {
+		child = list_entry(child->list.next, struct pdbg_target, list);
+		if ((next = target_map_child(child, system)))
+			return next;
+	} while (child != list_tail(&parent->children, struct pdbg_target, list));
+
+	return NULL;
 }
 
 enum pdbg_target_status pdbg_target_status(struct pdbg_target *target)
diff --git a/libpdbg/libpdbg.h b/libpdbg/libpdbg.h
index 722ddc2..4eec123 100644
--- a/libpdbg/libpdbg.h
+++ b/libpdbg/libpdbg.h
@@ -20,7 +20,7 @@ struct pdbg_target *__pdbg_next_compatible_node(struct pdbg_target *root,
                                                 struct pdbg_target *prev,
                                                 const char *compat);
 struct pdbg_target *__pdbg_next_target(const char *klass, struct pdbg_target *parent, struct pdbg_target *last);
-struct pdbg_target *__pdbg_next_child_target(struct pdbg_target *parent, struct pdbg_target *last);
+struct pdbg_target *__pdbg_next_child_target(struct pdbg_target *parent, struct pdbg_target *last, bool system);
 
 /*
  * Each target has a status associated with it. This is what each status means:
@@ -71,9 +71,9 @@ enum pdbg_backend { PDBG_DEFAULT_BACKEND = 0, PDBG_BACKEND_FSI, PDBG_BACKEND_I2C
 	     target = __pdbg_next_target(class, NULL, target))
 
 #define pdbg_for_each_child_target(parent, target)	      \
-	for (target = __pdbg_next_child_target(parent, NULL); \
+	for (target = __pdbg_next_child_target(parent, NULL, true); \
 	     target;					      \
-	     target = __pdbg_next_child_target(parent, target))
+	     target = __pdbg_next_child_target(parent, target, true))
 
 /* Return the first parent target of the given class, or NULL if the given
  * target does not have a parent of the given class. */
-- 
2.21.0