Finishes basic UART and serial console code for NUC120

git-svn-id: svn://svn.code.sf.net/p/nuttx/code/trunk@5661 42af7a65-404d-4744-a932-0658087f49c3

1 files changed, 988 insertions, 0 deletions

diff --git a/nuttx/arch/arm/src/nuc1xx/nuc_serial.c b/nuttx/arch/arm/src/nuc1xx/nuc_serial.c
new file mode 100644
index 000000000..0528fe8fe
--- /dev/null
+++ b/nuttx/arch/arm/src/nuc1xx/nuc_serial.c
@@ -0,0 +1,988 @@
+/****************************************************************************
+ * arch/arm/src/nuc1xx/nuc_serial.c
+ *
+ *   Copyright (C) 2012 Gregory Nutt. All rights reserved.
+ *   Author: Gregory Nutt <gnutt@nuttx.org>
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ *
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in
+ *    the documentation and/or other materials provided with the
+ *    distribution.
+ * 3. Neither the name NuttX nor the names of its contributors may be
+ *    used to endorse or promote products derived from this software
+ *    without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
+ * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
+ * COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
+ * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
+ * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
+ * OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
+ * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
+ * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
+ * ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
+ * POSSIBILITY OF SUCH DAMAGE.
+ *
+ ****************************************************************************/
+
+/****************************************************************************
+ * Included Files
+ ****************************************************************************/
+
+#include <nuttx/config.h>
+
+#include <sys/types.h>
+#include <stdint.h>
+#include <stdbool.h>
+#include <unistd.h>
+#include <semaphore.h>
+#include <string.h>
+#include <errno.h>
+#include <debug.h>
+
+#ifdef CONFIG_SERIAL_TERMIOS
+#  include <termios.h>
+#endif
+
+#include <nuttx/irq.h>
+#include <nuttx/arch.h>
+#include <nuttx/serial/serial.h>
+
+#include <arch/serial.h>
+#include <arch/board/board.h>
+
+#include "up_arch.h"
+#include "os_internal.h"
+#include "up_internal.h"
+
+#include "chip.h"
+#include "chip/nuc_uart.h"
+#include "nuc_serial.h"
+
+/****************************************************************************
+ * Pre-processor definitions
+ ****************************************************************************/
+
+/* If we are not using the serial driver for the console, then we still must
+ * provide some minimal implementation of up_putc.
+ */
+
+#if defined(USE_SERIALDRIVER) && defined(HAVE_UART)
+
+/* Configuration ************************************************************/
+
+/****************************************************************************
+ * Private Types
+ ****************************************************************************/
+
+struct nuc_dev_s
+{
+  uint32_t uartbase;  /* Base address of UART registers */
+  uint32_t baud;      /* Configured baud */
+  uint32_t ier;       /* Saved IER value */
+  uint8_t  irq;       /* IRQ associated with this UART */
+  uint8_t  parity;    /* 0=none, 1=odd, 2=even */
+  uint8_t  bits;      /* Number of bits (5-8) */
+  uint8_t  depth;     /* RX/TX FIFO depth */
+  bool     stopbits2; /* true: Configure with 2 stop bits instead of 1 */
+};
+
+/****************************************************************************
+ * Private Function Prototypes
+ ****************************************************************************/
+
+static int  up_setup(struct uart_dev_s *dev);
+static void up_shutdown(struct uart_dev_s *dev);
+static int  up_attach(struct uart_dev_s *dev);
+static void up_detach(struct uart_dev_s *dev);
+static int  up_interrupt(int irq, void *context);
+static int  up_ioctl(struct file *filep, int cmd, unsigned long arg);
+static int  up_receive(struct uart_dev_s *dev, uint32_t *status);
+static void up_rxint(struct uart_dev_s *dev, bool enable);
+static bool up_rxavailable(struct uart_dev_s *dev);
+static void up_send(struct uart_dev_s *dev, int ch);
+static void up_txint(struct uart_dev_s *dev, bool enable);
+static bool up_txready(struct uart_dev_s *dev);
+static bool up_txempty(struct uart_dev_s *dev);
+
+/****************************************************************************
+ * Private Variables
+ ****************************************************************************/
+
+struct uart_ops_s g_uart_ops =
+{
+  .setup          = up_setup,
+  .shutdown       = up_shutdown,
+  .attach         = up_attach,
+  .detach         = up_detach,
+  .ioctl          = up_ioctl,
+  .receive        = up_receive,
+  .rxint          = up_rxint,
+  .rxavailable    = up_rxavailable,
+  .send           = up_send,
+  .txint          = up_txint,
+  .txready        = up_txready,
+  .txempty        = up_txempty,
+};
+
+/* I/O buffers */
+
+#ifdef CONFIG_NUC_UART0
+static char g_uart0rxbuffer[CONFIG_UART0_RXBUFSIZE];
+static char g_uart0txbuffer[CONFIG_UART0_TXBUFSIZE];
+#endif
+
+#ifdef CONFIG_NUC_UART1
+static char g_uart1rxbuffer[CONFIG_UART1_RXBUFSIZE];
+static char g_uart1txbuffer[CONFIG_UART1_TXBUFSIZE];
+#endif
+
+#ifdef CONFIG_NUC_UART2
+static char g_uart2rxbuffer[CONFIG_UART2_RXBUFSIZE];
+static char g_uart2txbuffer[CONFIG_UART2_TXBUFSIZE];
+#endif
+
+#ifdef CONFIG_NUC_UART3
+static char g_uart3rxbuffer[CONFIG_UART3_RXBUFSIZE];
+static char g_uart3txbuffer[CONFIG_UART3_TXBUFSIZE];
+#endif
+
+/* This describes the state of the LPC17xx uart0 port. */
+
+#ifdef CONFIG_NUC_UART0
+static struct nuc_dev_s g_uart0priv =
+{
+  .uartbase       = NUC_UART0_BASE,
+  .baud           = CONFIG_UART0_BAUD,
+  .irq            = NUC_IRQ_UART0,
+  .parity         = CONFIG_UART0_PARITY,
+  .bits           = CONFIG_UART0_BITS,
+  .depth          = UART0_FIFO_DEPTH,
+  .stopbits2      = CONFIG_UART0_2STOP,
+};
+
+static uart_dev_t g_uart0port =
+{
+  .recv     =
+  {
+    .size   = CONFIG_UART0_RXBUFSIZE,
+    .buffer = g_uart0rxbuffer,
+  },
+  .xmit     =
+  {
+    .size   = CONFIG_UART0_TXBUFSIZE,
+    .buffer = g_uart0txbuffer,
+  },
+  .ops      = &g_uart_ops,
+  .priv     = &g_uart0priv,
+};
+#endif
+
+/* This describes the state of the LPC17xx uart1 port. */
+
+#ifdef CONFIG_NUC_UART1
+static struct nuc_dev_s g_uart1priv =
+{
+  .uartbase       = NUC_UART1_BASE,
+  .baud           = CONFIG_UART1_BAUD,
+  .irq            = NUC_IRQ_UART1,
+  .parity         = CONFIG_UART1_PARITY,
+  .bits           = CONFIG_UART1_BITS,
+  .depth          = UART1_FIFO_DEPTH,
+  .stopbits2      = CONFIG_UART1_2STOP,
+};
+
+static uart_dev_t g_uart1port =
+{
+  .recv     =
+  {
+    .size   = CONFIG_UART1_RXBUFSIZE,
+    .buffer = g_uart1rxbuffer,
+  },
+  .xmit     =
+  {
+    .size   = CONFIG_UART1_TXBUFSIZE,
+    .buffer = g_uart1txbuffer,
+  },
+  .ops      = &g_uart_ops,
+  .priv     = &g_uart1priv,
+};
+#endif
+
+/* This describes the state of the LPC17xx uart1 port. */
+
+#ifdef CONFIG_NUC_UART2
+static struct nuc_dev_s g_uart2priv =
+{
+  .uartbase       = NUC_UART2_BASE,
+  .baud           = CONFIG_UART2_BAUD,
+  .irq            = NUC_IRQ_UART2,
+  .parity         = CONFIG_UART2_PARITY,
+  .bits           = CONFIG_UART2_BITS,
+  .depth          = UART2_FIFO_DEPTH,
+  .stopbits2      = CONFIG_UART2_2STOP,
+};
+
+static uart_dev_t g_uart2port =
+{
+  .recv     =
+  {
+    .size   = CONFIG_UART2_RXBUFSIZE,
+    .buffer = g_uart2rxbuffer,
+  },
+  .xmit     =
+  {
+    .size   = CONFIG_UART2_TXBUFSIZE,
+    .buffer = g_uart2txbuffer,
+  },
+  .ops      = &g_uart_ops,
+  .priv     = &g_uart2priv,
+};
+#endif
+
+/* Which UART with be tty0/console and which tty1? tty2? */
+
+#ifdef HAVE_CONSOLE
+#  if defined(CONFIG_UART0_SERIAL_CONSOLE)
+#    define CONSOLE_DEV     g_uart0port     /* UART0=console */
+#    define TTYS0_DEV       g_uart0port     /* UART0=ttyS0 */
+#    ifdef CONFIG_NUC_UART1
+#      define TTYS1_DEV     g_uart1port     /* UART0=ttyS0;UART1=ttyS1 */
+#      ifdef CONFIG_NUC_UART2
+#        define TTYS2_DEV   g_uart2port     /* UART0=ttyS0;UART1=ttyS1;UART2=ttyS2 */
+#      else
+#        undef  TTYS2_DEV                   /* UART0=ttyS0;UART1=ttyS1;No ttyS2*/
+#      endif
+#    else
+#      ifdef CONFIG_NUC_UART2
+#        define TTYS1_DEV   g_uart2port     /* UART0=ttyS0;UART2=ttyS1 */
+#        undef  TTYS2_DEV                   /* UART0=ttyS0;UART2=ttyS1;No ttyS2*/
+#      else
+#        undef  TTYS1_DEV                   /* UART0=ttyS0;No ttyS1;No ttyS2 */
+#        undef  TTYS2_DEV                   /* No ttyS2 */
+#      endif
+#    endif
+#  elif defined(CONFIG_UART1_SERIAL_CONSOLE)
+#    define CONSOLE_DEV     g_uart1port     /* UART1=console */
+#    define TTYS0_DEV       g_uart1port     /* UART1=ttyS0 */
+#    ifdef CONFIG_NUC_UART0
+#      define TTYS1_DEV     g_uart0port     /* UART1=ttyS0;UART0=ttyS1 */
+#      ifdef CONFIG_NUC_UART2
+#        define TTYS2_DEV   g_uart2port     /* UART1=ttyS0;UART0=ttyS1;UART2=ttyS2 */
+#      else
+#        undef  TTYS2_DEV                   /* UART1=ttyS0;UART0=ttyS1;No ttyS2 */
+#      endif
+#    else
+#      ifdef CONFIG_NUC_UART2
+#        define TTYS1_DEV   g_uart2port     /* UART1=ttyS0;UART2=ttyS1 */
+#        undef  TTYS2_DEV                   /* UART1=ttyS0;UART2=ttyS1;No ttyS2 */
+#      else
+#        undef  TTYS1_DEV                   /* UART1=ttyS0;No ttyS1;No ttyS2 */
+#        undef  TTYS2_DEV                   /* No ttyS2 */
+#      endif
+#    endif
+#  elif defined(CONFIG_UART2_SERIAL_CONSOLE)
+#    define CONSOLE_DEV     g_uart2port     /* UART2=console */
+#    define TTYS0_DEV       g_uart2port     /* UART2=ttyS0 */
+#    ifdef CONFIG_NUC_UART2
+#      define TTYS1_DEV     g_uart0port     /* UART2=ttyS0;UART0=ttyS1 */
+#      ifdef CONFIG_NUC_UART1
+#        define TTYS2_DEV   g_uart1port     /* UART2=ttyS0;UART0=ttyS1;UART1=ttyS2 */
+#      else
+#        undef  TTYS2_DEV                   /* UART2=ttyS0;UART0=ttyS1;No ttyS2 */
+#      endif
+#    else
+#      ifdef CONFIG_NUC_UART1
+#        define TTYS1_DEV   g_uart1port     /* UART2=ttyS0;UART1=ttyS1 */
+#        undef TTYS2_DEV                    /* UART2=ttyS0;UART1=ttyS1;No ttyS2 */
+#      else
+#        undef TTYS1_DEV                    /* UART2=ttyS0;No ttyS1;No ttyS2 */
+#        undef TTYS2_DEV                    /* No ttyS2 */
+#      endif
+#    endif
+#else /* No console */
+#  define TTYS0_DEV       g_uart0port       /* UART0=ttyS0 */
+#  ifdef CONFIG_NUC_UART1
+#    define TTYS1_DEV     g_uart1port       /* UART0=ttyS0;UART1=ttyS1 */
+#    ifdef CONFIG_NUC_UART2
+#      define TTYS2_DEV   g_uart2port       /* UART0=ttyS0;UART1=ttyS1;UART2=ttyS2 */
+#    else
+#      undef  TTYS2_DEV                     /* UART0=ttyS0;UART1=ttyS1;No ttyS2 */
+#    endif
+#  else
+#    ifdef CONFIG_NUC_UART2
+#      define TTYS1_DEV   g_uart2port       /* UART0=ttyS0;UART2=ttyS1 */
+#      undef  TTYS2_DEV                     /* UART0=ttyS0;UART2=ttyS1;No ttyS2 */
+#    else
+#      undef TTYS1_DEV                      /* UART0=ttyS0;No ttyS1;No ttyS2 */
+#      undef TTYS2_DEV                      /* No ttyS2 */
+#    endif
+#  endif
+#endif /* HAVE_CONSOLE */
+
+/****************************************************************************
+ * Inline Functions
+ ****************************************************************************/
+
+/****************************************************************************
+ * Name: up_serialin
+ ****************************************************************************/
+
+static inline uint32_t up_serialin(struct nuc_dev_s *priv, int offset)
+{
+  return getreg32(priv->uartbase + offset);
+}
+
+/****************************************************************************
+ * Name: up_serialout
+ ****************************************************************************/
+
+static inline void up_serialout(struct nuc_dev_s *priv, int offset, uint32_t value)
+{
+  putreg32(value, priv->uartbase + offset);
+}
+
+/****************************************************************************
+ * Name: up_disableuartint
+ ****************************************************************************/
+
+static inline void up_disableuartint(struct nuc_dev_s *priv, uint32_t *ier)
+{
+  if (ier)
+    {
+      *ier = priv->ier & UART_IER_ALLIE;
+    }
+
+  priv->ier &= ~UART_IER_ALLIE;
+  up_serialout(priv, NUC_UART_IER_OFFSET, priv->ier);
+}
+
+/****************************************************************************
+ * Name: up_restoreuartint
+ ****************************************************************************/
+
+static inline void up_restoreuartint(struct nuc_dev_s *priv, uint32_t ier)
+{
+  priv->ier |= ier & UART_IER_ALLIE;
+  up_serialout(priv, NUC_UART_IER_OFFSET, priv->ier);
+}
+
+/****************************************************************************
+ * Private Functions
+ ****************************************************************************/
+
+/****************************************************************************
+ * Name: up_setup
+ *
+ * Description:
+ *   Configure the UART baud, bits, parity, fifos, etc. This method is
+ *   called the first time that the serial port is opened.
+ *
+ ****************************************************************************/
+
+static int up_setup(struct uart_dev_s *dev)
+{
+#ifndef CONFIG_SUPPRESS_NUC_UART_CONFIG
+  struct nuc_dev_s *priv = (struct nuc_dev_s*)dev->priv;
+  uint32_t regval;
+
+  /* Reset the TX FIFO */
+
+  regval = up_serialin(priv, NUC_UART_FCR_OFFSET
+  regval |= UART_FCR_TFR
+  up_serialout(priv, NUC_UART_FCR_OFFSET, regval);
+
+  /* Reset the RX FIFO */
+
+  regval = up_serialin(priv, NUC_UART_FCR_OFFSET
+  regval |= UART_FCR_RFR
+  up_serialout(priv, NUC_UART_FCR_OFFSET, regval);
+
+  /* Set Rx Trigger Level */
+
+  regval &= ~UART_FCR_FRITL_MASK;
+  regval |= UART_FCR_FRITL_4;
+  up_serialout(priv, NUC_UART_FCR_OFFSET, regval);
+
+  /* Set Parity & Data bits and Stop bits */
+
+  regval = 0;
+#if NUC_CONSOLE_BITS  == 5
+  regval |= UART_LCR_WLS_5;
+#elif NUC_CONSOLE_BITS  == 6
+  regval |= UART_LCR_WLS_6;
+#elif NUC_CONSOLE_BITS  == 7
+  regval |= UART_LCR_WLS_7;
+#elif NUC_CONSOLE_BITS  == 8
+  regval |= UART_LCR_WLS_8;
+#else
+  error "Unknown console UART data width"
+#endif
+
+#if NUC_CONSOLE_PARITY == 1
+  regval |= UART_LCR_PBE;
+#elif NUC_CONSOLE_PARITY == 2
+  regval |= (UART_LCR_PBE | UART_LCR_EPE);
+#endif
+
+
+#if NUC_CONSOLE_2STOP != 0
+  revgval |= UART_LCR_NSB;
+#endif
+
+  up_serialout(priv, NUC_UART_LCR_OFFSET, regval);
+
+  /* Set Time-Out values */
+
+  regval = UART_TOR_TOIC(40) |  UART_TOR_DLY(0);
+  up_serialout(priv, NUC_UART_TOR_OFFSET, regval);
+
+  /* Set the baud */
+
+  nuc_setbaud(CONSOLE_BASE, CONSOLE_BAUD);
+
+  /* Set up the IER */
+
+  priv->ier = up_serialin(priv, NUC_UART_IER_OFFSET);
+
+  /* Enable Flow Control in the Modem Control Register */
+  /* Not implemented */
+
+  return OK;
+}
+
+/****************************************************************************
+ * Name: up_shutdown
+ *
+ * Description:
+ *   Disable the UART.  This method is called when the serial port is closed
+ *
+ ****************************************************************************/
+
+static void up_shutdown(struct uart_dev_s *dev)
+{
+  struct nuc_dev_s *priv = (struct nuc_dev_s*)dev->priv;
+  up_disableuartint(priv, NULL);
+}
+
+/****************************************************************************
+ * Name: up_attach
+ *
+ * Description:
+ *   Configure the UART to operation in interrupt driven mode.  This method is
+ *   called when the serial port is opened.  Normally, this is just after the
+ *   the setup() method is called, however, the serial console may operate in
+ *   a non-interrupt driven mode during the boot phase.
+ *
+ *   RX and TX interrupts are not enabled when by the attach method (unless the
+ *   hardware supports multiple levels of interrupt enabling).  The RX and TX
+ *   interrupts are not enabled until the txint() and rxint() methods are called.
+ *
+ ****************************************************************************/
+
+static int up_attach(struct uart_dev_s *dev)
+{
+  struct nuc_dev_s *priv = (struct nuc_dev_s*)dev->priv;
+  int ret;
+
+  /* Attach and enable the IRQ */
+
+  ret = irq_attach(priv->irq, up_interrupt);
+  if (ret == OK)
+    {
+       /* Enable the interrupt (RX and TX interrupts are still disabled
+        * in the UART
+        */
+
+       up_enable_irq(priv->irq);
+    }
+
+  return ret;
+}
+
+/****************************************************************************
+ * Name: up_detach
+ *
+ * Description:
+ *   Detach UART interrupts.  This method is called when the serial port is
+ *   closed normally just before the shutdown method is called.  The exception is
+ *   the serial console which is never shutdown.
+ *
+ ****************************************************************************/
+
+static void up_detach(struct uart_dev_s *dev)
+{
+  struct nuc_dev_s *priv = (struct nuc_dev_s*)dev->priv;
+  up_disable_irq(priv->irq);
+  irq_detach(priv->irq);
+}
+
+/****************************************************************************
+ * Name: up_interrupt
+ *
+ * Description:
+ *   This is the UART interrupt handler.  It will be invoked when an
+ *   interrupt received on the 'irq'  It should call uart_transmitchars or
+ *   uart_receivechar to perform the appropriate data transfers.  The
+ *   interrupt handling logic must be able to map the 'irq' number into the
+ *   appropriate uart_dev_s structure in order to call these functions.
+ *
+ ****************************************************************************/
+
+static int up_interrupt(int irq, void *context)
+{
+  struct uart_dev_s *dev = NULL;
+  struct nuc_dev_s   *priv;
+  uint32_t           status;
+  int                passes;
+
+#ifdef CONFIG_NUC_UART0
+  if (g_uart0priv.irq == irq)
+    {
+      dev = &g_uart0port;
+    }
+  else
+#endif
+#ifdef CONFIG_NUC_UART1
+  if (g_uart1priv.irq == irq)
+    {
+      dev = &g_uart1port;
+    }
+  else
+#endif
+#ifdef CONFIG_NUC_UART2
+  if (g_uart2priv.irq == irq)
+    {
+      dev = &g_uart2port;
+    }
+  else
+#endif
+#ifdef CONFIG_NUC_UART3
+  if (g_uart3priv.irq == irq)
+    {
+      dev = &g_uart3port;
+    }
+  else
+#endif
+    {
+      PANIC(OSERR_INTERNAL);
+    }
+  priv = (struct nuc_dev_s*)dev->priv;
+
+  /* Loop until there are no characters to be transferred or,
+   * until we have been looping for a long time.
+   */
+
+  for (passes = 0; passes < 256; passes++)
+    {
+      /* Get the current UART interrupt status */
+
+       status = up_serialin(priv, NUC_UART_ISR_OFFSET);
+
+      /* Check if the RX FIFO is filled to the threshold value (OR if the RX
+       * timeout occurred without the FIFO being filled)
+       */
+
+      if ((status & UART_ISR_RDA_INT) != 0 || (status & UART_ISR_TOUT_INT) != 0)
+        {
+          uart_recvchars(dev);
+        }
+
+      /* Check if the transmit holding register is empty */
+
+      if ((status & UART_ISR_THRE_INT) != 0)
+        {
+          uart_xmitchars(dev);
+        }
+
+      /* Check for modem status */
+
+      if ((status & UART_ISR_MODEM_INT) != 0)
+        {
+          /* REVISIT:  Do we clear this be reading the modem status register? */
+
+          volatile uint32_t status = up_serialin(priv, NUC_UART_MSR_OFFSET);
+          vdbg("MSR: %08x\n", status);
+        }
+      
+      /* Check for line status */
+
+      if ((status & UART_ISR_RLS_INT) != 0)
+        {
+          /* REVISIT:  Do we clear this be reading the line status register? */
+
+          volatile uint32_t status = up_serialin(priv, NUC_UART_FSR_OFFSET);
+          vdbg("LSR: %08x\n", status);
+        }
+
+      /* Check for buffer errors */
+
+      if ((status & UART_ISR_BUF_ERR_INT) != 0)
+        {
+          /* REVISIT:  Do we clear this be reading the line status register? */
+
+          volatile uint32_t status = up_serialin(priv, NUC_UART_MSR_OFFSET);
+          vdbg("MSR: %08x\n", status);
+        }
+    }
+
+  return OK;
+}
+
+/****************************************************************************
+ * Name: up_ioctl
+ *
+ * Description:
+ *   All ioctl calls will be routed through this method
+ *
+ ****************************************************************************/
+
+static int up_ioctl(struct file *filep, int cmd, unsigned long arg)
+{
+  struct inode      *inode = filep->f_inode;
+  struct uart_dev_s *dev   = inode->i_private;
+  struct nuc_dev_s   *priv  = (struct nuc_dev_s*)dev->priv;
+  int                ret    = OK;
+
+  switch (cmd)
+    {
+    case TIOCSERGSTRUCT:
+      {
+        struct nuc_dev_s *user = (struct nuc_dev_s*)arg;
+        if (!user)
+          {
+            ret = -EINVAL;
+          }
+        else
+          {
+            memcpy(user, dev, sizeof(struct nuc_dev_s));
+          }
+      }
+      break;
+
+    case TIOCSBRK:   /* BSD compatibility: Turn break on, unconditionally */
+    case TIOCCBRK:   /* BSD compatibility: Turn break off, unconditionally */
+      ret = -ENOTTY; /* Not supported */
+      break;
+
+#ifdef CONFIG_SERIAL_TERMIOS
+    case TCGETS:
+      {
+        struct termios *termiosp = (struct termios*)arg;
+
+        if (!termiosp)
+          {
+            ret = -EINVAL;
+            break;
+          }
+
+        /* TODO:  Other termios fields are not yet returned.
+         * Note that cfsetospeed is not necessary because we have
+         * knowledge that only one speed is supported.
+         * Both cfset(i|o)speed() translate to cfsetspeed.
+         */
+
+        cfsetispeed(termiosp, priv->baud);
+      }
+      break;
+
+    case TCSETS:
+      {
+        struct termios *termiosp = (struct termios*)arg;
+        uint32_t           lcr;  /* Holds current values of line control register */
+        uint16_t           dl;   /* Divisor latch */
+
+        if (!termiosp)
+          {
+            ret = -EINVAL;
+            break;
+          }
+
+        /* TODO:  Handle other termios settings.
+         * Note that only cfgetispeed is used because we have knowledge
+         * that only one speed is supported.
+         */
+
+        /* Get the c_speed field in the termios struct */
+
+        priv->baud = cfgetispeed(termiosp);
+
+        /* Reset the baud */
+
+        nuc_setbaud(priv->base, priv->baud);
+      }
+      break;
+#endif
+
+    default:
+      ret = -ENOTTY;
+      break;
+    }
+
+  return ret;
+}
+
+/****************************************************************************
+ * Name: up_receive
+ *
+ * Description:
+ *   Called (usually) from the interrupt level to receive one
+ *   character from the UART.  Error bits associated with the
+ *   receipt are provided in the return 'status'.
+ *
+ ****************************************************************************/
+
+static int up_receive(struct uart_dev_s *dev, uint32_t *status)
+{
+  struct nuc_dev_s *priv = (struct nuc_dev_s*)dev->priv;
+  uint32_t rbr;
+
+  *status = up_serialin(priv, NUC_UART_FSR_OFFSET);
+  rbr     = up_serialin(priv, NUC_UART_RBR_OFFSET);
+  return rbr;
+}
+
+/****************************************************************************
+ * Name: up_rxint
+ *
+ * Description:
+ *   Call to enable or disable RX interrupts
+ *
+ ****************************************************************************/
+
+static void up_rxint(struct uart_dev_s *dev, bool enable)
+{
+  struct nuc_dev_s *priv = (struct nuc_dev_s*)dev->priv;
+  if (enable)
+    {
+#ifndef CONFIG_SUPPRESS_SERIAL_INTS
+      priv->ier |= (UART_IER_RDA_IEN | UART_IER_RLS_IEN | UART_IER_RTO_IEN |
+                    UART_IER_BUF_ERR_IEN  UART_IER_TIME_OUT_EN);
+#endif
+    }
+  else
+    {
+      priv->ier &= ~(UART_IER_RDA_IEN | UART_IER_RLS_IEN | UART_IER_RTO_IEN);
+    }
+
+  up_serialout(priv, NUC_UART_IER_OFFSET, priv->ier);
+}
+
+/****************************************************************************
+ * Name: up_rxavailable
+ *
+ * Description:
+ *   Return true if the receive fifo is not empty
+ *
+ ****************************************************************************/
+
+static bool up_rxavailable(struct uart_dev_s *dev)
+{
+  struct nuc_dev_s *priv = (struct nuc_dev_s*)dev->priv;
+  return ((up_serialin(priv, NUC_UART_FSR_OFFSET) & UART_FSR_RX_EMPTY) != 0);
+}
+
+/****************************************************************************
+ * Name: up_send
+ *
+ * Description:
+ *   This method will send one byte on the UART
+ *
+ ****************************************************************************/
+
+static void up_send(struct uart_dev_s *dev, int ch)
+{
+  struct nuc_dev_s *priv = (struct nuc_dev_s*)dev->priv;
+  up_serialout(priv, NUC_UART_THR_OFFSET, (uint32_t)ch);
+}
+
+/****************************************************************************
+ * Name: up_txint
+ *
+ * Description:
+ *   Call to enable or disable TX interrupts
+ *
+ ****************************************************************************/
+
+static void up_txint(struct uart_dev_s *dev, bool enable)
+{
+  struct nuc_dev_s *priv = (struct nuc_dev_s*)dev->priv;
+  irqstate_t flags;
+
+  flags = irqsave();
+  if (enable)
+    {
+#ifndef CONFIG_SUPPRESS_SERIAL_INTS
+      priv->ier |= (UART_IER_THRE_IEN | UART_IER_BUF_ERR_IEN);
+      up_serialout(priv, NUC_UART_IER_OFFSET, priv->ier);
+
+      /* Fake a TX interrupt here by just calling uart_xmitchars() with
+       * interrupts disabled (note this may recurse).
+       */
+
+      uart_xmitchars(dev);
+#endif
+    }
+  else
+    {
+      priv->ier &= ~UART_IER_THRE_IEN;
+      up_serialout(priv, NUC_UART_IER_OFFSET, priv->ier);
+    }
+
+  irqrestore(flags);
+}
+
+/****************************************************************************
+ * Name: up_txready
+ *
+ * Description:
+ *   Return true if the tranmsit fifo is not full
+ *
+ ****************************************************************************/
+
+static bool up_txready(struct uart_dev_s *dev)
+{
+  struct nuc_dev_s *priv = (struct nuc_dev_s*)dev->priv;
+  uint32_t regval;
+  int depth;
+
+  regval = up_serialin(priv, NUC_UART_FSR_OFFSET);
+  depth  = (regval & UART_FSR_TX_POINTER_MASK) >> UART_FSR_TX_POINTER_SHIFT;
+  return depth < priv->depth;
+}
+
+/****************************************************************************
+ * Name: up_txempty
+ *
+ * Description:
+ *   Return true if the transmit fifo is empty
+ *
+ ****************************************************************************/
+
+static bool up_txempty(struct uart_dev_s *dev)
+{
+  struct nuc_dev_s *priv = (struct nuc_dev_s*)dev->priv;
+  return ((up_serialin(priv, NUC_UART_FSR_OFFSET) & UART_FSR_TE_FLAG) != 0);
+}
+
+/****************************************************************************
+ * Public Funtions
+ ****************************************************************************/
+
+/****************************************************************************
+ * Name: up_serialinit
+ *
+ * Description:
+ *   Performs the low level UART initialization early in debug so that the
+ *   serial console will be available during bootup.  This must be called
+ *   before up_serialinit.
+ *
+ *   NOTE: Configuration of the CONSOLE UART was performed by up_lowsetup()
+ *   very early in the boot sequence.
+ *
+ ****************************************************************************/
+
+void up_earlyserialinit(void)
+{
+  /* Configuration whichever UART is the console */
+
+#ifdef CONSOLE_DEV
+  CONSOLE_DEV.isconsole = true;
+  up_setup(&CONSOLE_DEV);
+#endif
+}
+
+/****************************************************************************
+ * Name: up_serialinit
+ *
+ * Description:
+ *   Register serial console and serial ports.  This assumes that
+ *   up_earlyserialinit was called previously.
+ *
+ ****************************************************************************/
+
+void up_serialinit(void)
+{
+#ifdef CONSOLE_DEV
+  (void)uart_register("/dev/console", &CONSOLE_DEV);
+#endif
+#ifdef TTYS0_DEV
+  (void)uart_register("/dev/ttyS0", &TTYS0_DEV);
+#endif
+#ifdef TTYS1_DEV
+  (void)uart_register("/dev/ttyS1", &TTYS1_DEV);
+#endif
+#ifdef TTYS2_DEV
+  (void)uart_register("/dev/ttyS2", &TTYS2_DEV);
+#endif
+}
+
+/****************************************************************************
+ * Name: up_putc
+ *
+ * Description:
+ *   Provide priority, low-level access to support OS debug  writes
+ *
+ ****************************************************************************/
+
+int up_putc(int ch)
+{
+#ifdef HAVE_CONSOLE
+  struct nuc_dev_s *priv = (struct nuc_dev_s*)CONSOLE_DEV.priv;
+  uint32_t ier;
+  up_disableuartint(priv, &ier);
+#endif
+
+  /* Check for LF */
+
+  if (ch == '\n')
+    {
+      /* Add CR */
+
+      up_lowputc('\r');
+    }
+
+  up_lowputc(ch);
+#ifdef HAVE_CONSOLE
+  up_restoreuartint(priv, ier);
+#endif
+
+  return ch;
+}
+
+#else /* USE_SERIALDRIVER */
+
+/****************************************************************************
+ * Name: up_putc
+ *
+ * Description:
+ *   Provide priority, low-level access to support OS debug writes
+ *
+ ****************************************************************************/
+
+int up_putc(int ch)
+{
+#ifdef HAVE_UART
+  /* Check for LF */
+
+  if (ch == '\n')
+    {
+      /* Add CR */
+
+      up_lowputc('\r');
+    }
+
+  up_lowputc(ch);
+#endif
+  return ch;
+}
+
+#endif /* USE_SERIALDRIVER */