From: Sascha Hauer <s.hauer@pengutronix.de>

devicetrees may have a linux,stdout-path or stdout-path property
in the chosen node describing the console device. This adds a helper
function to match a device against this property and retrieve the options
so a driver can call add_preferred_console for a matching device.

Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>
Signed-off-by: Jean-Christophe PLAGNIOL-VILLARD <redacted>
Cc: linux-serial@vger.kernel.org
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: kernel@pengutronix.de
Cc: Alan Cox <redacted>
Cc: Grant Likely <redacted>
Cc: Nicolas Ferre <redacted>
---
 drivers/of/base.c  |   46 ++++++++++++++++++++++++++++++++++++++++++++++
 include/linux/of.h |    7 +++++++
 2 files changed, 53 insertions(+)

diff --git a/drivers/of/base.c b/drivers/of/base.c
index f2f63c8..72c49ce 100644
--- a/drivers/of/base.c
+++ b/drivers/of/base.c

@@ -1470,3 +1470,49 @@ const char *of_prop_next_string(struct property *prop, const char *cur)
 	return curv;
 }
 EXPORT_SYMBOL_GPL(of_prop_next_string);
+
+/**
+ * of_device_is_stdout_path - check if a device node matches the
+ *			      linux,stdout-path property
+ * @np:		Pointer to the given device_node
+ * @option:	parsed option
+ *
+ * Check if this device node matches the linux,stdout-path property
+ * in the chosen node. return true if yes, false otherwise.
+ */
+int of_device_is_stdout_path(struct device_node *dn, char **option)
+{
+	const char *name;
+	struct device_node *dn_stdout;
+	bool is_stdout = 0;
+	const char *tmp;
+	const char *tmp_option;
+
+	name = of_get_property(of_chosen, "linux,stdout-path", NULL);
+	if (name == NULL)
+		name = of_get_property(of_chosen, "stdout-path", NULL);
+
+	if (name == NULL)
+		return 0;
+
+	tmp_option = strchr(name, ':');
+
+	tmp = kstrndup(name, strlen(name) - strlen(tmp_option), GFP_KERNEL);