[PATCH 25/41] TTY: add tty_port_link_device

[Jiri Slaby]

This is for those drivers which do not have dynamic device creation
(do not call tty_port_register_device) and do not want to implement
tty->ops->install (will not call tty_port_install). They still have to
provide the link somehow though.

And this newly added function is exactly to serve that purpose.

Signed-off-by: Jiri Slaby <jslaby@xxxxxxx>
---
 drivers/tty/tty_port.c |   22 +++++++++++++++++++++-
 include/linux/tty.h    |    2 ++
 2 files changed, 23 insertions(+), 1 deletion(-)

diff --git a/drivers/tty/tty_port.c b/drivers/tty/tty_port.c
index b36b33a..b4be732 100644
--- a/drivers/tty/tty_port.c
+++ b/drivers/tty/tty_port.c
@@ -34,6 +34,26 @@ void tty_port_init(struct tty_port *port)
 EXPORT_SYMBOL(tty_port_init);
 
 /**
+ * tty_port_link_device - link tty and tty_port
+ * @port: tty_port of the device
+ * @driver: tty_driver for this device
+ * @index: index of the tty
+ *
+ * Provide the tty layer wit ha link from a tty (specified by @index) to a
+ * tty_port (@port). Use this only if neither tty_port_register_device nor
+ * tty_port_install is used in the driver. If used, this has to be called before
+ * tty_register_driver.
+ */
+void tty_port_link_device(struct tty_port *port,
+		struct tty_driver *driver, unsigned index)
+{
+	if (WARN_ON(index >= driver->num))
+		return;
+	driver->ports[index] = port;
+}
+EXPORT_SYMBOL_GPL(tty_port_link_device);
+
+/**
  * tty_port_register_device - register tty device
  * @port: tty_port of the device
  * @driver: tty_driver for this device
@@ -48,7 +68,7 @@ struct device *tty_port_register_device(struct tty_port *port,
 		struct tty_driver *driver, unsigned index,
 		struct device *device)
 {
-	driver->ports[index] = port;
+	tty_port_link_device(port, driver, index);
 	return tty_register_device(driver, index, device);
 }
 EXPORT_SYMBOL_GPL(tty_port_register_device);
diff --git a/include/linux/tty.h b/include/linux/tty.h
index a39e723..aebf2ab 100644
--- a/include/linux/tty.h
+++ b/include/linux/tty.h
@@ -496,6 +496,8 @@ extern int tty_write_lock(struct tty_struct *tty, int ndelay);
 #define tty_is_writelocked(tty)  (mutex_is_locked(&tty->atomic_write_lock))
 
 extern void tty_port_init(struct tty_port *port);
+extern void tty_port_link_device(struct tty_port *port,
+		struct tty_driver *driver, unsigned index);
 extern struct device *tty_port_register_device(struct tty_port *port,
 		struct tty_driver *driver, unsigned index,
 		struct device *device);
-- 
1.7.10.4


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