3 files changed, 86 insertions, 0 deletions

diff --git a/drivers/tty/serial/serial_base.h b/drivers/tty/serial/serial_base.h
index c74c548f0db6..327a18b1813b 100644
--- a/drivers/tty/serial/serial_base.h
+++ b/drivers/tty/serial/serial_base.h
@@ -45,3 +45,19 @@ 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_add_preferred_console(struct uart_driver *drv,
+				      struct uart_port *port);
+
+#else
+
+static inline
+int serial_base_add_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..4ef26a1b09b1 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 +205,71 @@ void serial_base_port_device_remove(struct serial_port_device *port_dev)
 	put_device(&port_dev->dev);
 }
 
+#ifdef CONFIG_SERIAL_CORE_CONSOLE
+
+static int serial_base_add_one_prefcon(const char *match, const char *dev_name,
+				       int port_id)
+{
+	int ret;
+
+	ret = add_preferred_console_match(match, dev_name, port_id);
+	if (ret == -ENOENT)
+		return 0;
+
+	return ret;
+}
+
+static int serial_base_add_prefcon(const char *name, int idx)
+{
+	const char *char_match __free(kfree) = NULL;
+
+	/* Handle the traditional character device name style console=ttyS0 */
+	char_match = kasprintf(GFP_KERNEL, "%s%i", name, idx);
+	if (!char_match)
+		return -ENOMEM;
+
+	return serial_base_add_one_prefcon(char_match, name, idx);
+}
+
+/**
+ * serial_base_add_preferred_console - Adds a preferred console
+ * @drv: Serial port device driver
+ * @port: Serial port instance
+ *
+ * Tries to add a preferred console for a serial port if specified in the
+ * kernel command line. Supports both the traditional character device such
+ * as console=ttyS0, and a hardware addressing based console=DEVNAME:0.0
+ * style name.
+ *
+ * Translates the kernel command line option using a hardware based addressing
+ * console=DEVNAME:0.0 to the serial port character device such as ttyS0.
+ * Cannot be called early for ISA ports, depends on struct device.
+ *
+ * Note that duplicates are ignored by add_preferred_console().
+ *
+ * Return: 0 on success, negative error code on failure.
+ */
+int serial_base_add_preferred_console(struct uart_driver *drv,
+				      struct uart_port *port)
+{
+	const char *port_match __free(kfree) = NULL;
+	int ret;
+
+	ret = serial_base_add_prefcon(drv->dev_name, port->line);
+	if (ret)
+		return ret;
+
+	port_match = kasprintf(GFP_KERNEL, "%s:%i.%i", dev_name(port->dev),
+			       port->ctrl_id, port->port_id);
+	if (!port_match)
+		return -ENOMEM;
+
+	/* Translate a hardware addressing style console=DEVNAME:0.0 */
+	return serial_base_add_one_prefcon(port_match, drv->dev_name, port->line);
+}
+
+#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 3c0931fba1c6..a78ded8c60b5 100644
--- a/drivers/tty/serial/serial_core.c
+++ b/drivers/tty/serial/serial_core.c
@@ -3393,6 +3393,10 @@ int serial_core_register_port(struct uart_driver *drv, struct uart_port *port)
 	if (ret)
 		goto err_unregister_ctrl_dev;
 
+	ret = serial_base_add_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;