[PATCH v2 19/24] serdev: Instantiate a ttydev serdev if acpi and of fails

[Ricardo Ribalda Delgado]

If a serdev ttyport controller does not have an acpi nor an of child,
create a ttydev as a child of that controller.

Doing this allows the removal, addition and replacement of ttydev devices
at runtime.

Cc: Rob Herring <r...@kernel.org>
Cc: Johan Hovold <jo...@kernel.org>
Cc: Greg Kroah-Hartman <gre...@linuxfoundation.org>
Cc: Jiri Slaby <jsl...@suse.com>
Cc: Andy Shevchenko <andy.shevche...@gmail.com>
Signed-off-by: Ricardo Ribalda Delgado <ricardo.riba...@gmail.com>
---
 drivers/tty/serdev/core.c | 49 ++++++++++++++++++++++++++++++---------
 1 file changed, 38 insertions(+), 11 deletions(-)

diff --git a/drivers/tty/serdev/core.c b/drivers/tty/serdev/core.c
index 584cb994213a..587d2796b3d5 100644
--- a/drivers/tty/serdev/core.c
+++ b/drivers/tty/serdev/core.c
@@ -628,6 +628,26 @@ static inline int acpi_serdev_register_devices(struct 
serdev_controller *ctrl)
 }
 #endif /* CONFIG_ACPI */
 
+#if IS_ENABLED(CONFIG_SERIAL_DEV_CTRL_TTYDEV)
+static int serdev_controller_add_ttydev(struct serdev_controller *ctrl)
+{
+       struct serdev_device *serdev;
+       int err;
+
+       serdev = serdev_device_alloc(ctrl);
+       if (!serdev)
+               return -ENOMEM;
+
+       strcpy(serdev->modalias, "ttydev");
+
+       err = serdev_device_add(serdev);
+       if (err)
+               serdev_device_put(serdev);
+
+       return err;
+}
+#endif
+
 /**
  * serdev_controller_add() - Add an serdev controller
  * @ctrl:      controller to be registered.
@@ -637,7 +657,7 @@ static inline int acpi_serdev_register_devices(struct 
serdev_controller *ctrl)
  */
 int serdev_controller_add(struct serdev_controller *ctrl)
 {
-       int ret_of, ret_acpi, ret;
+       int ret_of, ret_acpi, ret, ret_tty = -ENODEV;
 
        /* Can't register until after driver model init */
        if (WARN_ON(!is_registered))
@@ -648,21 +668,28 @@ int serdev_controller_add(struct serdev_controller *ctrl)
                return ret;
 
        ret_of = of_serdev_register_devices(ctrl);
+       if (!ret_of)
+               goto out_dev_ok;
+
        ret_acpi = acpi_serdev_register_devices(ctrl);
-       if (ret_of && ret_acpi) {
-               dev_dbg(&ctrl->dev, "no devices registered: of:%d acpi:%d\n",
-                       ret_of, ret_acpi);
-               ret = -ENODEV;
-               goto out_dev_del;
-       }
+       if (!ret_acpi)
+               goto out_dev_ok;
+
+#if IS_ENABLED(CONFIG_SERIAL_DEV_CTRL_TTYDEV)
+       ret_tty = serdev_controller_add_ttydev(ctrl);
+       if (!ret_tty)
+               goto out_dev_ok;
+#endif
 
+       dev_dbg(&ctrl->dev, "no devices registered: of:%d acpi:%d tty:%d\n",
+               ret_of, ret_acpi, ret_tty);
+       device_del(&ctrl->dev);
+       return -ENODEV;
+
+out_dev_ok:
        dev_dbg(&ctrl->dev, "serdev%d registered: dev:%p\n",
                ctrl->nr, &ctrl->dev);
        return 0;
-
-out_dev_del:
-       device_del(&ctrl->dev);
-       return ret;
 };
 EXPORT_SYMBOL_GPL(serdev_controller_add);
 
-- 
2.17.1