Merged in rnouse/nuttx (pull request #9)

Custom IOCTL support and more shadow warnings fixup

drivers/serial/Kconfig

@@ -318,6 +318,10 @@ config 16550_SUPRESS_CONFIG
 		that configures the 16550_UART.  In that case, you may want to
 		just leave the existing console configuration in place.  Default: n
 
+config SERIAL_UART_ARCH_IOCTL
+	bool "Platform has own custom IOCTL"
+	default n
+
 config 16550_REGINCR
 	int "Address increment between 16550 registers"
 	default 1

drivers/serial/uart_16550.c

@@ -864,7 +864,15 @@ static int u16550_ioctl(struct file *filep, int cmd, unsigned long arg)
   struct inode      *inode = filep->f_inode;
   struct uart_dev_s *dev   = inode->i_private;
   struct u16550_s   *priv  = (struct u16550_s*)dev->priv;
-  int                ret   = OK;
+
+#ifdef CONFIG_SERIAL_UART_ARCH_IOCTL
+  int ret = uart_ioctl(filep, cmd, arg);
+
+  if (ret != -ENOTTY)
+    {
+      return ret;
+    }
+#endif
 
   switch (cmd)
     {