serial: sh-sci: Move uart_register_driver call to device probe

uart_register_driver call binds the driver to a specific device
node through tty_register_driver call. This should typically
happen during device probe call.

In a multiplatform scenario, it is possible that multiple serial
drivers are part of the kernel. Currently the driver registration fails
if multiple serial drivers with overlapping major/minor numbers are
included.

Signed-off-by: Sjoerd Simons <sjoerd.simons@collabora.co.uk>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/drivers/tty/serial/sh-sci.c b/drivers/tty/serial/sh-sci.c
index 21b06cf1f15bc642dd73857e16dc9667301a62ea..54de985ad214b24841e075b30892509fc7442965 100644 (file)
--- a/drivers/tty/serial/sh-sci.c
+++ b/drivers/tty/serial/sh-sci.c
@@ -2962,6 +2962,7 @@ static inline int sci_probe_earlyprintk(struct platform_device *pdev)
 
 static const char banner[] __initconst = "SuperH (H)SCI(F) driver initialized";
 
+static DEFINE_MUTEX(sci_uart_registration_lock);
 static struct uart_driver sci_uart_driver = {
        .owner          = THIS_MODULE,
        .driver_name    = "sci",
@@ -3090,6 +3091,16 @@ static int sci_probe_single(struct platform_device *dev,
                return -EINVAL;
        }
 
+       mutex_lock(&sci_uart_registration_lock);
+       if (!sci_uart_driver.state) {
+               ret = uart_register_driver(&sci_uart_driver);
+               if (ret) {
+                       mutex_unlock(&sci_uart_registration_lock);
+                       return ret;
+               }
+       }
+       mutex_unlock(&sci_uart_registration_lock);
+
        ret = sci_init_single(dev, sciport, index, p, false);
        if (ret)
                return ret;
@@ -3213,24 +3224,17 @@ static struct platform_driver sci_driver = {
 
 static int __init sci_init(void)
 {
-       int ret;
-
        pr_info("%s\n", banner);
 
-       ret = uart_register_driver(&sci_uart_driver);
-       if (likely(ret == 0)) {
-               ret = platform_driver_register(&sci_driver);
-               if (unlikely(ret))
-                       uart_unregister_driver(&sci_uart_driver);
-       }
-
-       return ret;
+       return platform_driver_register(&sci_driver);
 }
 
 static void __exit sci_exit(void)
 {
        platform_driver_unregister(&sci_driver);
-       uart_unregister_driver(&sci_uart_driver);
+
+       if (sci_uart_driver.state)
+               uart_unregister_driver(&sci_uart_driver);
 }
 
 #ifdef CONFIG_SERIAL_SH_SCI_CONSOLE