[PATCH] serial: i.MX: evaluate linux,stdout-path property

[Sascha Hauer <s.hauer@pengutronix.de>]

devicetrees may have the linux,stdout-path property to specify the
console. This patch adds support to the i.MX serial driver for this.

Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>
---

I was originally looking for a more generic way to handle this, but
since a struct console has no device associated to it, it's not
possible to match a console with a device in a generic way. So we
just call add_preferred_console from the driver and let it go down
to a string matching in the console code.
If anyone has a better idea how to handle this, please let me know.
Otherwise I'm happy to see this patch applied aswell.

Thanks
 Sascha

 drivers/tty/serial/imx.c |   29 +++++++++++++++++++++++++++++
 1 file changed, 29 insertions(+)

diff --git a/drivers/tty/serial/imx.c b/drivers/tty/serial/imx.c
index e309e8b..b52c4a7 100644
--- a/drivers/tty/serial/imx.c
+++ b/drivers/tty/serial/imx.c
@@ -1397,6 +1397,32 @@ static int serial_imx_resume(struct platform_device *dev)
 
 #ifdef CONFIG_OF
 /*
+ * Check if this device matches the linux,stdout-path property
+ * in the chosen node. return true if yes, false otherwise
+ */
+static int serial_imx_is_stdoutpath(struct platform_device *pdev)
+{
+	struct device_node *dn;
+	const char *name;
+
+	if (!IS_ENABLED(CONFIG_SERIAL_IMX_CONSOLE))
+		return 0;
+
+	name = of_get_property(of_chosen, "linux,stdout-path", NULL);
+	if (name == NULL)
+		return 0;
+
+	dn = of_find_node_by_path(name);
+	if (!dn)
+		return 0;
+
+	if (dn == pdev->dev.of_node)
+		return 1;
+
+	return 0;
+}
+
+/*
  * This function returns 1 iff pdev isn't a device instatiated by dt, 0 iff it
  * could successfully get all information from dt or a negative errno.
  */
@@ -1427,6 +1453,9 @@ static int serial_imx_probe_dt(struct imx_port *sport,
 
 	sport->devdata = of_id->data;
 
+	if (serial_imx_is_stdoutpath(pdev))
+		add_preferred_console(imx_reg.cons->name, sport->port.line, 0);
+
 	return 0;
 }
 #else
-- 
1.7.10.4