serial: pl010: 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/amba-pl010.c b/drivers/tty/serial/amba-pl010.c
index f2f25107510980ca8625f8a5658fc79739a85219..24180adb1cbb8b873512c07c6b6884299b7d35d6 100644 (file)
--- a/drivers/tty/serial/amba-pl010.c
+++ b/drivers/tty/serial/amba-pl010.c
@@ -697,6 +697,7 @@ static struct console amba_console = {
 #define AMBA_CONSOLE   NULL
 #endif
 
+static DEFINE_MUTEX(amba_reg_lock);
 static struct uart_driver amba_reg = {
        .owner                  = THIS_MODULE,
        .driver_name            = "ttyAM",
@@ -749,6 +750,19 @@ static int pl010_probe(struct amba_device *dev, const struct amba_id *id)
        amba_ports[i] = uap;
 
        amba_set_drvdata(dev, uap);
+
+       mutex_lock(&amba_reg_lock);
+       if (!amba_reg.state) {
+               ret = uart_register_driver(&amba_reg);
+               if (ret < 0) {
+                       mutex_unlock(&amba_reg_lock);
+                       dev_err(uap->port.dev,
+                               "Failed to register AMBA-PL010 driver\n");
+                       return ret;
+               }
+       }
+       mutex_unlock(&amba_reg_lock);
+
        ret = uart_add_one_port(&amba_reg, &uap->port);
        if (ret)
                amba_ports[i] = NULL;
@@ -760,12 +774,18 @@ static int pl010_remove(struct amba_device *dev)
 {
        struct uart_amba_port *uap = amba_get_drvdata(dev);
        int i;
+       bool busy = false;
 
        uart_remove_one_port(&amba_reg, &uap->port);
 
        for (i = 0; i < ARRAY_SIZE(amba_ports); i++)
                if (amba_ports[i] == uap)
                        amba_ports[i] = NULL;
+               else if (amba_ports[i])
+                       busy = true;
+
+       if (!busy)
+               uart_unregister_driver(&amba_reg);
 
        return 0;
 }
@@ -816,23 +836,14 @@ static struct amba_driver pl010_driver = {
 
 static int __init pl010_init(void)
 {
-       int ret;
-
        printk(KERN_INFO "Serial: AMBA driver\n");
 
-       ret = uart_register_driver(&amba_reg);
-       if (ret == 0) {
-               ret = amba_driver_register(&pl010_driver);
-               if (ret)
-                       uart_unregister_driver(&amba_reg);
-       }
-       return ret;
+       return  amba_driver_register(&pl010_driver);
 }
 
 static void __exit pl010_exit(void)
 {
        amba_driver_unregister(&pl010_driver);
-       uart_unregister_driver(&amba_reg);
 }
 
 module_init(pl010_init);