1 files changed, 30 insertions, 15 deletions

diff --git a/drivers/tty/serial/sh-sci.c b/drivers/tty/serial/sh-sci.c
index 71707e8e6e3f..da5ddfc14778 100644
--- a/drivers/tty/serial/sh-sci.c
+++ b/drivers/tty/serial/sh-sci.c
@@ -1450,8 +1450,7 @@ static struct dma_chan *sci_request_dma_chan(struct uart_port *port,
 	chan = dma_request_slave_channel(port->dev,
 					 dir == DMA_MEM_TO_DEV ? "tx" : "rx");
 	if (!chan) {
-		dev_warn(port->dev,
-			 "dma_request_slave_channel_compat failed\n");
+		dev_warn(port->dev, "dma_request_slave_channel failed\n");
 		return NULL;
 	}
 
@@ -1558,7 +1557,16 @@ static void sci_free_dma(struct uart_port *port)
 	if (s->chan_rx)
 		sci_rx_dma_release(s, false);
 }
-#else
+
+static void sci_flush_buffer(struct uart_port *port)
+{
+	/*
+	 * In uart_flush_buffer(), the xmit circular buffer has just been
+	 * cleared, so we have to reset tx_dma_len accordingly.
+	 */
+	to_sci_port(port)->tx_dma_len = 0;
+}
+#else /* !CONFIG_SERIAL_SH_SCI_DMA */
 static inline void sci_request_dma(struct uart_port *port)
 {
 }
@@ -1566,7 +1574,9 @@ static inline void sci_request_dma(struct uart_port *port)
 static inline void sci_free_dma(struct uart_port *port)
 {
 }
-#endif
+
+#define sci_flush_buffer	NULL
+#endif /* !CONFIG_SERIAL_SH_SCI_DMA */
 
 static irqreturn_t sci_rx_interrupt(int irq, void *ptr)
 {
@@ -2581,6 +2591,7 @@ static const struct uart_ops sci_uart_ops = {
 	.break_ctl	= sci_break_ctl,
 	.startup	= sci_startup,
 	.shutdown	= sci_shutdown,
+	.flush_buffer	= sci_flush_buffer,
 	.set_termios	= sci_set_termios,
 	.pm		= sci_pm,
 	.type		= sci_type,
@@ -2950,6 +2961,7 @@ 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",
@@ -3078,6 +3090,16 @@ 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;
@@ -3201,24 +3223,17 @@ 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