xhci: dbc: Don't call dbc_tty_init() on every dbc tty probe

The current workaround to call the dbc_tty_init() in probe is
not working in case we have several xhci devices with dbc enabled.

dbc_tty_init() should be called only once by a module init call when
module is loaded.

until dbgtty is its own module call dbc_tty_init() from xhci
module init call.

Same is true for unloading and dbc_tty_exit()

Signed-off-by: Mathias Nyman <[e-mail]>
Link: https://lore.kernel.org/r/[e-mail]
Signed-off-by: Greg Kroah-Hartman <[e-mail]>

drivers/usb/host/xhci-dbgcap.c

···
 	return ret;
 }
 #endif /* CONFIG_PM */
+
+int xhci_dbc_init(void)
+{
+	return dbc_tty_init();
+}
+
+void xhci_dbc_exit(void)
+{
+	dbc_tty_exit();
+}

drivers/usb/host/xhci-dbgcap.h

···
 #ifdef CONFIG_USB_XHCI_DBGCAP
 int xhci_create_dbc_dev(struct xhci_hcd *xhci);
 void xhci_remove_dbc_dev(struct xhci_hcd *xhci);
+int xhci_dbc_init(void);
+void xhci_dbc_exit(void);
+int dbc_tty_init(void);
+void dbc_tty_exit(void);
 int xhci_dbc_tty_probe(struct device *dev, void __iomem *res, struct xhci_hcd *xhci);
 void xhci_dbc_tty_remove(struct xhci_dbc *dbc);
 struct xhci_dbc *xhci_alloc_dbc(struct device *dev, void __iomem *res,
···
 static inline void xhci_remove_dbc_dev(struct xhci_hcd *xhci)
 {
 }
-
+static inline int xhci_dbc_init(void)
+{
+	return 0;
+}
+static inline void xhci_dbc_exit(void)
+{
+}
 static inline int xhci_dbc_suspend(struct xhci_hcd *xhci)
 {
 	return 0;

drivers/usb/host/xhci-dbgtty.c

···
 #include "xhci.h"
 #include "xhci-dbgcap.h"
 
-static int dbc_tty_init(void);
-static void dbc_tty_exit(void);
-
 static struct tty_driver *dbc_tty_driver;
 
 static inline struct dbc_port *dbc_to_port(struct xhci_dbc *dbc)
···
 	struct dbc_port		*port;
 	int			status;
 
-	/* dbc_tty_init will be called by module init() in the future */
-	status = dbc_tty_init();
-	if (status)
-		return status;
+	if (!dbc_tty_driver)
+		return -ENODEV;
 
 	port = kzalloc(sizeof(*port), GFP_KERNEL);
-	if (!port) {
-		status = -ENOMEM;
-		goto out;
-	}
+	if (!port)
+		return -ENOMEM;
 
 	dbc_tty_driver->driver_state = port;
 
···
 	return 0;
 out2:
 	kfree(port);
-out:
-	/* dbc_tty_exit will be called by module_exit() in the future */
-	dbc_tty_exit();
+
 	return status;
 }
 
···
 
 	xhci_dbc_remove(dbc);
 	kfree(port);
-
-	/* dbc_tty_exit will be called by  module_exit() in the future */
-	dbc_tty_exit();
 }
 
-static int dbc_tty_init(void)
+int dbc_tty_init(void)
 {
 	int		ret;
 
···
 	return ret;
 }
 
-static void dbc_tty_exit(void)
+void dbc_tty_exit(void)
 {
 	if (dbc_tty_driver) {
 		tty_unregister_driver(dbc_tty_driver);

drivers/usb/host/xhci.c

···
 		return -ENODEV;
 
 	xhci_debugfs_create_root();
+	xhci_dbc_init();
 
 	return 0;
 }
···
 static void __exit xhci_hcd_fini(void)
 {
 	xhci_debugfs_remove_root();
+	xhci_dbc_exit();
 }
 
 module_init(xhci_hcd_init);