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 <[email protected]> --- drivers/tty/serial/amba-pl010.c | 27 +++++++++++++++++---------- 1 file changed, 17 insertions(+), 10 deletions(-) diff --git a/drivers/tty/serial/amba-pl010.c b/drivers/tty/serial/amba-pl010.c index f2f251075109..74a1d3b2e45d 100644 --- a/drivers/tty/serial/amba-pl010.c +++ b/drivers/tty/serial/amba-pl010.c @@ -749,6 +749,16 @@ static int pl010_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) { + dev_err(uap->port.dev, + "Failed to register AMBA-PL010 driver\n"); + return ret; + } + } + ret = uart_add_one_port(&amba_reg, &uap->port); if (ret) amba_ports[i] = NULL; @@ -760,12 +770,18 @@ 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 +832,14 @@ 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); -- 2.11.0
