[PATCH v6 38/42] drivers/of: Unflatten subordinate nodes after specified level

[Gavin Shan]

unflatten_dt_node() is called recursively to unflatten FDT nodes
with the assumption that FDT blob has only one root node, which
isn't true when the FDT blob represents device sub-tree. This
improves the function to supporting device sub-tree that have
multiple nodes in the first level:

   * Rename original unflatten_dt_node() to __unflatten_dt_node().
   * Wrapper unflatten_dt_node() calls __unflatten_dt_node() with
     adjusted current node depth to 1 to avoid underflow.

Signed-off-by: Gavin Shan <gwshan at linux.vnet.ibm.com>
---
 drivers/of/fdt.c | 53 ++++++++++++++++++++++++++++++++++++++++-------------
 1 file changed, 40 insertions(+), 13 deletions(-)

diff --git a/drivers/of/fdt.c b/drivers/of/fdt.c
index 0749656..a18a2ce 100644
--- a/drivers/of/fdt.c
+++ b/drivers/of/fdt.c
@@ -161,7 +161,7 @@ static void *unflatten_dt_alloc(void **mem, unsigned long size,
 }
 
 /**
- * unflatten_dt_node - Alloc and populate a device_node from the flat tree
+ * __unflatten_dt_node - Alloc and populate a device_node from the flat tree
  * @blob: The parent device tree blob
  * @mem: Memory chunk to use for allocating device nodes and properties
  * @poffset: pointer to node in flat tree
@@ -171,20 +171,20 @@ static void *unflatten_dt_alloc(void **mem, unsigned long size,
  * @dryrun: If true, do not allocate device nodes but still calculate needed
  * memory size
  */
-static void * unflatten_dt_node(const void *blob,
+static void *__unflatten_dt_node(const void *blob,
 				void *mem,
 				int *poffset,
 				struct device_node *dad,
 				struct device_node **nodepp,
 				unsigned long fpsize,
-				bool dryrun)
+				bool dryrun,
+				int *depth)
 {
 	const __be32 *p;
 	struct device_node *np;
 	struct property *pp, **prev_pp = NULL;
 	const char *pathp;
 	unsigned int l, allocl;
-	static int depth = 0;
 	int old_depth;
 	int offset;
 	int has_name = 0;
@@ -337,13 +337,25 @@ static void * unflatten_dt_node(const void *blob,
 			np->type = "<NULL>";
 	}
 
-	old_depth = depth;
-	*poffset = fdt_next_node(blob, *poffset, &depth);
-	if (depth < 0)
-		depth = 0;
-	while (*poffset > 0 && depth > old_depth)
-		mem = unflatten_dt_node(blob, mem, poffset, np, NULL,
-					fpsize, dryrun);
+	/* Multiple nodes might be in the first depth level if
+	 * the device tree is sub-tree. All nodes in current
+	 * or deeper depth are unflattened after it returns.
+	 */
+	old_depth = *depth;
+	*poffset = fdt_next_node(blob, *poffset, depth);
+	while (*poffset > 0) {
+		if (*depth < old_depth)
+			break;
+
+		if (*depth == old_depth)
+			mem = __unflatten_dt_node(blob, mem, poffset,
+						  dad, NULL, fpsize,
+						  dryrun, depth);
+		else if (*depth > old_depth)
+			mem = __unflatten_dt_node(blob, mem, poffset,
+						  np, NULL, fpsize,
+						  dryrun, depth);
+	}
 
 	if (*poffset < 0 && *poffset != -FDT_ERR_NOTFOUND)
 		pr_err("unflatten: error %d processing FDT\n", *poffset);
@@ -369,6 +381,20 @@ static void * unflatten_dt_node(const void *blob,
 	return mem;
 }
 
+static void *unflatten_dt_node(const void *blob,
+			       void *mem,
+			       int *poffset,
+			       struct device_node *dad,
+			       struct device_node **nodepp,
+			       bool dryrun)
+{
+	int depth = 1;
+
+	return __unflatten_dt_node(blob, mem, poffset,
+				   dad, nodepp, 0,
+				   dryrun, &depth);
+}
+
 /**
  * __unflatten_device_tree - create tree of device_nodes from flat blob
  *
@@ -408,7 +434,8 @@ static void __unflatten_device_tree(const void *blob,
 
 	/* First pass, scan for size */
 	start = 0;
-	size = (unsigned long)unflatten_dt_node(blob, NULL, &start, NULL, NULL, 0, true);
+	size = (unsigned long)unflatten_dt_node(blob, NULL, &start,
+						NULL, NULL, true);
 	size = ALIGN(size, 4);
 
 	pr_debug("  size is %lx, allocating...\n", size);
@@ -423,7 +450,7 @@ static void __unflatten_device_tree(const void *blob,
 
 	/* Second pass, do actual unflattening */
 	start = 0;
-	unflatten_dt_node(blob, mem, &start, NULL, mynodes, 0, false);
+	unflatten_dt_node(blob, mem, &start, NULL, mynodes, false);
 	if (be32_to_cpup(mem + size) != 0xdeadbeef)
 		pr_warning("End of tree marker overwritten: %08x\n",
 			   be32_to_cpup(mem + size));
-- 
2.1.0