On Mon, 26 Aug 2013 16:39:17 +0200, Marek Szyprowski [off-list ref] wrote:

Add a function to scan the flattened device-tree starting from the
node given by the path. It is used to extract information (like reserved
memory), which is required on early boot before we can unflatten the tree.

Signed-off-by: Marek Szyprowski <m.szyprowski@samsung.com>
Acked-by: Michal Nazarewicz <redacted>
Acked-by: Tomasz Figa <redacted>
Reviewed-by: Rob Herring <redacted>

Some nits below, but otherwise:

Acked-by: Grant Likely <redacted>

I'm happy to take this through the DT tree, or have you take it via the
CMA tree.

Nit: since this is an iterator, I'd like to see "iter" in the function
name.

+{
+	struct fdt_scan_status *st = data;
+
+	/*
+	 * if scan at the requested fdt node has been completed,
+	 * return -ENXIO to abort further scanning
+	 */
+	if (depth <= st->depth)
+		return -ENXIO;
+
+	/* requested fdt node has been found, so call iterator function */
+	if (st->found)
+		return st->iterator(node, uname, depth, st->data);
+
+	/* check if scanning automata is entering next level of fdt nodes */
+	if (depth == st->depth + 1 &&
+	    strncmp(st->name, uname, st->namelen) == 0 &&
+	    uname[st->namelen] == 0) {
+		st->depth += 1;
+		if (st->name[st->namelen] == 0) {
+			st->found = 1;
+		} else {
+			const char *next = st->name + st->namelen + 1;
+			st->name = next;
+			st->namelen = strcspn(next, "/");
+		}
+		return 0;

The above return statement is redundant.

+	}
+
+	/* scan next fdt node */
+	return 0;
+}
+
+/**
+ * of_scan_flat_dt_by_path - scan flattened tree blob and call callback on each
+ *			     child of the given path.
+ * @path: path to start searching for children
+ * @it: callback function
+ * @data: context data pointer
+ *
+ * This function is used to scan the flattened device-tree starting from the
+ * node given by path. It is used to extract information (like reserved
+ * memory), which is required on ealy boot before we can unflatten the tree.
+ */
+int __init of_scan_flat_dt_by_path(const char *path,
+	int (*it)(unsigned long node, const char *name, int depth, void *data),
+	void *data)

Nit: Please match the indentation convention used by of_scan_flat_dt().
This current version is really hard to read.

+{
+	struct fdt_scan_status st = {path, 0, -1, 0, it, data};

This is a little fragile. If the structure gets modified, this line
will break. I know it results in more text, but please use explicit data
member assignments in initializers.

+	int ret = 0;
+
+	if (initial_boot_params)

Nit:
	if (!initial_boot_params)
		return 0;

+                ret = of_scan_flat_dt(fdt_scan_node_by_path, &st);

Nit: inconsitent indentation (tabs vs. spaces)

+
+	if (!st.found)
+		return -ENOENT;
+	else if (ret == -ENXIO)	/* scan has been completed */
+		return 0;
+	else
+		return ret;

Both uses of 'else' above are redundant. The only way the execution will
pass that point is if it was the else case!