serial: pl011: 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 same default major/minor numbers are
included in the kernel.

A typical case is observed with amba-pl011 and samsung-uart drivers.

Signed-off-by: Tushar Behera <tushar.behera@linaro.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/drivers/tty/serial/amba-pl011.c b/drivers/tty/serial/amba-pl011.c
index d58783d364e3a9443a7c2723e635467e54b014cd..d4eda24aa68ba6392be747fe63176a79aaad7311 100644 (file)
--- a/drivers/tty/serial/amba-pl011.c
+++ b/drivers/tty/serial/amba-pl011.c
@@ -2154,9 +2154,19 @@ static int pl011_probe(struct amba_device *dev, const struct amba_id *id)
        amba_ports[i] = uap;
 
        amba_set_drvdata(dev, uap);
+
+       if (!amba_reg.state) {
+               ret = uart_register_driver(&amba_reg);
+               if (ret < 0) {
+                       pr_err("Failed to register AMBA-PL011 driver\n");
+                       return ret;
+               }
+       }
+
        ret = uart_add_one_port(&amba_reg, &uap->port);
        if (ret) {
                amba_ports[i] = NULL;
+               uart_unregister_driver(&amba_reg);
                pl011_dma_remove(uap);
        }
  out:
@@ -2175,6 +2185,7 @@ static int pl011_remove(struct amba_device *dev)
                        amba_ports[i] = NULL;
 
        pl011_dma_remove(uap);
+       uart_unregister_driver(&amba_reg);
        return 0;
 }
 
@@ -2230,22 +2241,14 @@ static struct amba_driver pl011_driver = {
 
 static int __init pl011_init(void)
 {
-       int ret;
        printk(KERN_INFO "Serial: AMBA PL011 UART driver\n");
 
-       ret = uart_register_driver(&amba_reg);
-       if (ret == 0) {
-               ret = amba_driver_register(&pl011_driver);
-               if (ret)
-                       uart_unregister_driver(&amba_reg);
-       }
-       return ret;
+       return amba_driver_register(&pl011_driver);
 }
 
 static void __exit pl011_exit(void)
 {
        amba_driver_unregister(&pl011_driver);
-       uart_unregister_driver(&amba_reg);
 }
 
 /*