Merge tag 'tty-4.13-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/tty

Pull tty/serial updates from Greg KH:
 "Here is the large tty/serial patchset for 4.13-rc1.

  A lot of tty and serial driver updates are in here, along with some
  fixups for some __get/put_user usages that were reported. Nothing
  huge, just lots of development by a number of different developers,
  full details in the shortlog.

  All of these have been in linux-next for a while"

* tag 'tty-4.13-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/tty: (71 commits)
  tty: serial: lpuart: add a more accurate baud rate calculation method
  tty: serial: lpuart: add earlycon support for imx7ulp
  tty: serial: lpuart: add imx7ulp support
  dt-bindings: serial: fsl-lpuart: add i.MX7ULP support
  tty: serial: lpuart: add little endian 32 bit register support
  tty: serial: lpuart: refactor lpuart32_{read|write} prototype
  tty: serial: lpuart: introduce lpuart_soc_data to represent SoC property
  serial: imx-serial - move DMA buffer configuration to DT
  serial: imx: Enable RTSD only when needed
  serial: imx: Remove unused members from imx_port struct
  serial: 8250: 8250_omap: Fix race b/w dma completion and RX timeout
  serial: 8250: Fix THRE flag usage for CAP_MINI
  tty/serial: meson_uart: update to stable bindings
  dt-bindings: serial: Add bindings for the Amlogic Meson UARTs
  serial: Delete dead code for CIR serial ports
  serial: sirf: make of_device_ids const
  serial/mpsc: switch to dma_alloc_attrs
  tty: serial: Add Actions Semi Owl UART earlycon
  dt-bindings: serial: Document Actions Semi Owl UARTs
  tty/serial: atmel: make the driver DT only
  ...

1 files changed, 21 insertions, 10 deletions

diff --git a/drivers/tty/serial/amba-pl010.c b/drivers/tty/serial/amba-pl010.c
index f2f251075109..24180adb1cbb 100644
--- 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);