From e22912db37182cc7e05970c8d7145bd8dc45c0aa Mon Sep 17 00:00:00 2001
From: Sebastien Lorquet <sebastien@lorquet.fr>
Date: Tue, 1 Aug 2017 06:30:52 -0600
Subject: [PATCH] drivers/serial/serial.c:  Add support for TCFLUSH

---
 drivers/serial/serial.c | 31 +++++++++++++++++++++++++++++++
 1 file changed, 31 insertions(+)

diff --git a/drivers/serial/serial.c b/drivers/serial/serial.c
index 49417a9685..cc0e2fe441 100644
--- a/drivers/serial/serial.c
+++ b/drivers/serial/serial.c
@@ -977,6 +977,37 @@ static int uart_ioctl(FAR struct file *filep, int cmd, unsigned long arg)
               ret = 0;
             }
             break;
+
+#ifdef CONFIG_SERIAL_TERMIOS
+          case TCFLSH:
+            {
+              /* Empty the tx/rx buffers */
+
+              irqstate_t flags = enter_critical_section();
+
+              if (arg == TCIFLUSH || arg == TCIOFLUSH)
+                {
+                  dev->recv.head = 0;
+                  dev->recv.tail = 0;
+                }
+
+              if (arg == TCOFLUSH || arg == TCIOFLUSH)
+                {
+                  dev->xmit.head = 0;
+                  dev->xmit.tail = 0;
+                }
+
+              leave_critical_section(flags);
+            }
+            break;
+
+#if 0
+          case TCDRN:
+            {
+            }
+            break;
+#endif
+#endif
         }
     }