On 2016/1/26 20:11, Stefano Stabellini wrote:

On Sat, 23 Jan 2016, Shannon Zhao wrote:

quoted

quoted

From: Shannon Zhao <redacted>

Sometimes it needs to check if there is a node in FDT by full path.
Introduce this helper to get the specified name subnode if it exists.

Signed-off-by: Shannon Zhao <redacted>
---
CC: Rob Herring <redacted>
---
 drivers/of/fdt.c       | 35 +++++++++++++++++++++++++++++++++++
 include/linux/of_fdt.h |  2 ++
 2 files changed, 37 insertions(+)

diff --git a/drivers/of/fdt.c b/drivers/of/fdt.c
index 655f79d..112ec16 100644
--- a/drivers/of/fdt.c
+++ b/drivers/of/fdt.c

@@ -645,6 +645,41 @@ int __init of_scan_flat_dt(int (*it)(unsigned long node,
 }
 
 /**
+ * of_get_flat_dt_subnode_by_name - get subnode of specified node by name
+ *
+ * @node: the parent node
+ * @uname: the name of subnode
+ * @return offset of the subnode, or -FDT_ERR_NOTFOUND if there is none
+ */
+
+int of_get_flat_dt_subnode_by_name(unsigned long node, const char *uname)
+{
+	const void *blob = initial_boot_params;
+	int offset;
+	const char *pathp;
+
+	/* Find first subnode if it exists */
+	offset = fdt_first_subnode(blob, node);
+	if (offset < 0)
+		return -FDT_ERR_NOTFOUND;
+	pathp = fdt_get_name(blob, offset, NULL);
+	if (strncmp(pathp, uname, strlen(uname)) == 0)
+		return offset;

Wouldn't this check succeed even if uname is "uefi" and the node
name is actually "uefiiiii"?  You might have to use strcmp.

Ah, yes. Will fix this.

quoted

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+	/* Find other subnodes */
+	do {
+		offset = fdt_next_subnode(blob, offset);
+		if (offset < 0)
+			return -FDT_ERR_NOTFOUND;
+		pathp = fdt_get_name(blob, offset, NULL);
+		if (strncmp(pathp, uname, strlen(uname)) == 0)
+			return offset;
+	} while (offset >= 0);

Rather than writing the name check twice, I think it would be best to
code this loop as:

    for (offset = fdt_first_subnode(blob, offset);
         offset >= 0;
         offset = fdt_next_subnode(blob, offset)) {

         /* do name check */

Thanks for your suggestion. Will change this.

-- 
Shannon