[PATCH 2/3] serial: core: Add serial_base_match_and_update_preferred_console()

[Tony Lindgren <tony.lindgren@linux.intel.com>]

Let's add serial_base_match_and_update_preferred_console() for consoles
using DEVNAME:0.0 style naming.

The earlier approach to add it caused issues in the kernel command line
ordering as we were calling __add_preferred_console() again for the
deferred consoles.

Signed-off-by: Tony Lindgren <tony.lindgren@linux.intel.com>
---
 drivers/tty/serial/serial_base.h     | 16 ++++++++++++
 drivers/tty/serial/serial_base_bus.c | 37 ++++++++++++++++++++++++++++
 drivers/tty/serial/serial_core.c     |  4 +++
 3 files changed, 57 insertions(+)

diff --git a/drivers/tty/serial/serial_base.h b/drivers/tty/serial/serial_base.h
index b6c38d2edfd4..0d50db5b660b 100644
--- a/drivers/tty/serial/serial_base.h
+++ b/drivers/tty/serial/serial_base.h
@@ -49,3 +49,19 @@ void serial_ctrl_unregister_port(struct uart_driver *drv, struct uart_port *port
 
 int serial_core_register_port(struct uart_driver *drv, struct uart_port *port);
 void serial_core_unregister_port(struct uart_driver *drv, struct uart_port *port);
+
+#ifdef CONFIG_SERIAL_CORE_CONSOLE
+
+int serial_base_match_and_update_preferred_console(struct uart_driver *drv,
+						   struct uart_port *port);
+
+#else
+
+static inline
+int serial_base_match_and_update_preferred_console(struct uart_driver *drv,
+						   struct uart_port *port)
+{
+	return 0;
+}
+
+#endif
diff --git a/drivers/tty/serial/serial_base_bus.c b/drivers/tty/serial/serial_base_bus.c
index 4df2a4b10445..d822499ba9d6 100644
--- a/drivers/tty/serial/serial_base_bus.c
+++ b/drivers/tty/serial/serial_base_bus.c
@@ -8,6 +8,7 @@
  * The serial core bus manages the serial core controller instances.
  */
 
+#include <linux/cleanup.h>
 #include <linux/container_of.h>
 #include <linux/device.h>
 #include <linux/idr.h>
@@ -204,6 +205,42 @@ void serial_base_port_device_remove(struct serial_port_device *port_dev)
 	put_device(&port_dev->dev);
 }
 
+#ifdef CONFIG_SERIAL_CORE_CONSOLE
+
+/**
+ * serial_base_match_and_update_preferred_console - Match and update a preferred console
+ * @drv: Serial port device driver
+ * @port: Serial port instance
+ *
+ * Tries to match and update the preferred console for a serial port for
+ * the kernel command line option console=DEVNAME:0.0.
+ *
+ * Cannot be called early for ISA ports, depends on struct device.
+ *
+ * Return: 0 on success, negative error code on failure.
+ */
+int serial_base_match_and_update_preferred_console(struct uart_driver *drv,
+						   struct uart_port *port)
+{
+	const char *port_match __free(kfree) = NULL;
+	int ret;
+
+	port_match = kasprintf(GFP_KERNEL, "%s:%d.%d", dev_name(port->dev),
+			       port->ctrl_id, port->port_id);
+	if (!port_match)
+		return -ENOMEM;
+
+	ret = match_devname_and_update_preferred_console(port_match,
+							 drv->dev_name,
+							 port->line);
+	if (ret == -ENOENT)
+		return 0;
+
+	return ret;
+}
+
+#endif
+
 static int serial_base_init(void)
 {
 	int ret;
diff --git a/drivers/tty/serial/serial_core.c b/drivers/tty/serial/serial_core.c
index 2a8006e3d687..9a18d0b95a41 100644
--- a/drivers/tty/serial/serial_core.c
+++ b/drivers/tty/serial/serial_core.c
@@ -3422,6 +3422,10 @@ int serial_core_register_port(struct uart_driver *drv, struct uart_port *port)
 	if (ret)
 		goto err_unregister_ctrl_dev;
 
+	ret = serial_base_match_and_update_preferred_console(drv, port);
+	if (ret)
+		goto err_unregister_port_dev;
+
 	ret = serial_core_add_one_port(drv, port);
 	if (ret)
 		goto err_unregister_port_dev;
-- 
2.45.2