Fix basic QEMU port

git-svn-id: svn://svn.code.sf.net/p/nuttx/code/trunk@3357 42af7a65-404d-4744-a932-0658087f49c3

1 files changed, 1092 insertions, 0 deletions

diff --git a/nuttx/drivers/serial/uart_16550.c b/nuttx/drivers/serial/uart_16550.c
new file mode 100755
index 000000000..e65d5cced
--- /dev/null
+++ b/nuttx/drivers/serial/uart_16550.c
@@ -0,0 +1,1092 @@
+/****************************************************************************
+ * drivers/serial/uart_16550.c
+ * Serial driver for 16550 UART
+ *
+ *   Copyright (C) 2011 Gregory Nutt. All rights reserved.
+ *   Author: Gregory Nutt <spudmonkey@racsa.co.cr>
+ *
+ * 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>
+
+#include <nuttx/irq.h>
+#include <nuttx/arch.h>
+#include <nuttx/serial.h>
+#include <nuttx/uart_16550.h>
+
+#include <arch/board/board.h>
+
+#ifdef CONFIG_UART_16550
+
+/****************************************************************************
+ * Pre-processor definitions
+ ****************************************************************************/
+
+/****************************************************************************
+ * Private Types
+ ****************************************************************************/
+
+struct uart_16550_s
+{
+  uart_addrwidth_t uartbase;  /* Base address of UART registers */
+  uint32_t         baud;      /* Configured baud */
+  uint32_t         uartclk;   /* UART clock frequency */
+  uart_datawidth_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 (7 or 8) */
+  bool             stopbits2; /* true: Configure with 2 stop bits instead of 1 */
+};
+
+/****************************************************************************
+ * Private Function Prototypes
+ ****************************************************************************/
+
+static int  uart_setup(struct uart_dev_s *dev);
+static void uart_shutdown(struct uart_dev_s *dev);
+static int  uart_attach(struct uart_dev_s *dev);
+static void uart_detach(struct uart_dev_s *dev);
+static int  uart_interrupt(int irq, void *context);
+static int  uart_ioctl(struct file *filep, int cmd, unsigned long arg);
+static int  uart_receive(struct uart_dev_s *dev, uint32_t *status);
+static void uart_rxint(struct uart_dev_s *dev, bool enable);
+static bool uart_rxavailable(struct uart_dev_s *dev);
+static void uart_send(struct uart_dev_s *dev, int ch);
+static void uart_txint(struct uart_dev_s *dev, bool enable);
+static bool uart_txready(struct uart_dev_s *dev);
+static bool uart_txempty(struct uart_dev_s *dev);
+
+/****************************************************************************
+ * Private Variables
+ ****************************************************************************/
+
+struct uart_ops_s g_uart_ops =
+{
+  .setup          = uart_setup,
+  .shutdown       = uart_shutdown,
+  .attach         = uart_attach,
+  .detach         = uart_detach,
+  .ioctl          = uart_ioctl,
+  .receive        = uart_receive,
+  .rxint          = uart_rxint,
+  .rxavailable    = uart_rxavailable,
+  .send           = uart_send,
+  .txint          = uart_txint,
+  .txready        = uart_txready,
+  .txempty        = uart_txempty,
+};
+
+/* I/O buffers */
+
+#ifdef CONFIG_16550_UART0
+static char g_uart0rxbuffer[CONFIG_UART0_RXBUFSIZE];
+static char g_uart0txbuffer[CONFIG_UART0_TXBUFSIZE];
+#endif
+#ifdef CONFIG_16550_UART1
+static char g_uart1rxbuffer[CONFIG_UART1_RXBUFSIZE];
+static char g_uart1txbuffer[CONFIG_UART1_TXBUFSIZE];
+#endif
+#ifdef CONFIG_16550_UART2
+static char g_uart2rxbuffer[CONFIG_UART1_RXBUFSIZE];
+static char g_uart2txbuffer[CONFIG_UART1_TXBUFSIZE];
+#endif
+#ifdef CONFIG_16550_UART3
+static char g_uart3rxbuffer[CONFIG_UART1_RXBUFSIZE];
+static char g_uart3txbuffer[CONFIG_UART1_TXBUFSIZE];
+#endif
+
+/* This describes the state of the LPC17xx uart0 port. */
+
+#ifdef CONFIG_16550_UART0
+static struct uart_16550_s g_uart0priv =
+{
+  .uartbase       = CONFIG_16550_UART0_BASE,
+  .baud           = CONFIG_UART0_BAUD,
+  .uartclk        = CONFIG_16550_UART0_CLOCK,
+  .irq            = CONFIG_16550_UART0_IRQ,
+  .parity         = CONFIG_UART0_PARITY,
+  .bits           = CONFIG_UART0_BITS,
+  .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_16550_UART1
+static struct uart_16550_s g_uart1priv =
+{
+  .uartbase       = CONFIG_16550_UART1_BASE,
+  .baud           = CONFIG_UART1_BAUD,
+  .uartclk        = CONFIG_16550_UART1_CLOCK,
+  .irq            = CONFIG_16550_UART1_IRQ,
+  .parity         = CONFIG_UART1_PARITY,
+  .bits           = CONFIG_UART1_BITS,
+  .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_16550_UART2
+static struct uart_16550_s g_uart2priv =
+{
+  .uartbase       = CONFIG_16550_UART2_BASE,
+  .baud           = CONFIG_UART2_BAUD,
+  .uartclk        = CONFIG_16550_UART2_CLOCK,
+  .irq            = CONFIG_16550_UART2_IRQ,
+  .parity         = CONFIG_UART2_PARITY,
+  .bits           = CONFIG_UART2_BITS,
+  .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
+
+/* This describes the state of the LPC17xx uart1 port. */
+
+#ifdef CONFIG_16550_UART3
+static struct uart_16550_s g_uart3priv =
+{
+  .uartbase       = CONFIG_16550_UART3_BASE,
+  .baud           = CONFIG_UART3_BAUD,
+  .uartclk        = CONFIG_16550_UART3_CLOCK,
+  .irq            = CONFIG_16550_UART3_IRQ,
+  .parity         = CONFIG_UART3_PARITY,
+  .bits           = CONFIG_UART3_BITS,
+  .stopbits2      = CONFIG_UART3_2STOP,
+};
+
+static uart_dev_t g_uart3port =
+{
+  .recv     =
+  {
+    .size   = CONFIG_UART3_RXBUFSIZE,
+    .buffer = g_uart3rxbuffer,
+  },
+  .xmit     =
+  {
+    .size   = CONFIG_UART3_TXBUFSIZE,
+    .buffer = g_uart3txbuffer,
+   },
+  .ops      = &g_uart_ops,
+  .priv     = &g_uart3priv,
+};
+#endif
+
+/* Which UART with be tty0/console and which tty1? tty2? tty3? */
+
+#if defined(CONFIG_UART0_SERIAL_CONSOLE)
+#  define CONSOLE_DEV     g_uart0port      /* UART0=console */
+#  define TTYS0_DEV       g_uart0port      /* UART0=ttyS0 */
+#  ifdef CONFIG_16550_UART1
+#    define TTYS1_DEV     g_uart1port      /* UART0=ttyS0;UART1=ttyS1 */
+#    ifdef CONFIG_16550_UART2
+#      define TTYS2_DEV   g_uart2port      /* UART0=ttyS0;UART1=ttyS1;UART2=ttyS2 */
+#      ifdef CONFIG_16550_UART3
+#        define TTYS3_DEV g_uart3port      /* UART0=ttyS0;UART1=ttyS1;UART2=ttyS2;UART3=ttyS3 */
+#      else
+#        undef TTYS3_DEV                   /* UART0=ttyS0;UART1=ttyS1;UART2=ttyS;No ttyS3 */
+#      endif
+#    else
+#      ifdef CONFIG_16550_UART3
+#        define TTYS2_DEV g_uart3port     /* UART0=ttyS0;UART1=ttyS1;UART3=ttys2;No ttyS3 */
+#      else
+#        undef TTYS2_DEV                  /* UART0=ttyS0;UART1=ttyS1;No ttyS2;No ttyS3 */
+#      endif
+#      undef TTYS3_DEV                    /* No ttyS3 */
+#    endif
+#  else
+#    ifdef CONFIG_16550_UART2
+#      define TTYS1_DEV   g_uart2port    /* UART0=ttyS0;UART2=ttyS1;No ttyS3 */
+#      ifdef CONFIG_16550_UART3
+#        define TTYS2_DEV g_uart3port    /* UART0=ttyS0;UART2=ttyS1;UART3=ttyS2;No ttyS3 */
+#      else
+#        undef TTYS2_DEV                 /* UART0=ttyS0;UART2=ttyS1;No ttyS2;No ttyS3 */
+#      endif
+#      undef TTYS3_DEV                   /* No ttyS3 */
+#    else
+#      ifdef CONFIG_16550_UART3
+#        define TTYS1_DEV g_uart3port    /* UART0=ttyS0;UART3=ttyS1;No ttyS2;No ttyS3 */
+#      else
+#        undef TTYS1_DEV                 /* UART0=ttyS0;No ttyS1;No ttyS2;No ttyS3 */
+#      endif
+#        undef TTYS2_DEV                  /* No ttyS2 */
+#      undef TTYS3_DEV                    /* No ttyS3 */
+#    endif
+#  endif
+#elif defined(CONFIG_UART1_SERIAL_CONSOLE)
+#  define CONSOLE_DEV     g_uart1port     /* UART1=console */
+#  define TTYS0_DEV       g_uart1port     /* UART1=ttyS0 */
+#  ifdef CONFIG_16550_UART
+#    define TTYS1_DEV     g_uart0port     /* UART1=ttyS0;UART0=ttyS1 */
+#    ifdef CONFIG_16550_UART2
+#      define TTYS2_DEV   g_uart2port     /* UART1=ttyS0;UART0=ttyS1;UART2=ttyS2 */
+#      ifdef CONFIG_16550_UART3
+#        define TTYS3_DEV g_uart3port     /* UART1=ttyS0;UART0=ttyS1;UART2=ttyS2;UART3=ttyS3 */
+#      else
+#        undef TTYS3_DEV                  /* UART1=ttyS0;UART0=ttyS1;UART2=ttyS;No ttyS3 */
+#      endif
+#    else
+#      ifdef CONFIG_16550_UART3
+#        define TTYS2_DEV g_uart3port     /* UART1=ttyS0;UART0=ttyS1;UART3=ttys2;No ttyS3 */
+#      else
+#        undef TTYS2_DEV                  /* UART1=ttyS0;UART0=ttyS1;No ttyS2;No ttyS3 */
+#      endif
+#      undef TTYS3_DEV                    /* No ttyS3 */
+#    endif
+#  else
+#    ifdef CONFIG_16550_UART2
+#      define TTYS1_DEV   g_uart2port     /* UART1=ttyS0;UART2=ttyS1 */
+#      ifdef CONFIG_16550_UART3
+#        define TTYS2_DEV g_uart3port     /* UART1=ttyS0;UART2=ttyS1;UART3=ttyS2;No ttyS3 */
+#      else
+#        undef TTYS2_DEV                  /* UART1=ttyS0;UART2=ttyS1;No ttyS2;No ttyS3 */
+#      endif
+#      undef TTYS3_DEV                    /* No ttyS3 */
+#    else
+#      ifdef CONFIG_16550_UART3
+#        define TTYS1_DEV   g_uart3port   /* UART1=ttyS0;UART3=ttyS1;No ttyS2;No ttyS3 */
+#      else
+#        undef TTYS1_DEV                  /* UART1=ttyS0;No ttyS1;No ttyS2;No ttyS3 */
+#      endif
+#      undef TTYS2_DEV                    /* No ttyS2 */
+#      undef TTYS3_DEV                    /* No ttyS3 */
+#    endif
+#  endif
+#elif defined(CONFIG_UART2_SERIAL_CONSOLE)
+#  define CONSOLE_DEV     g_uart2port     /* UART2=console */
+#  define TTYS0_DEV       g_uart2port     /* UART2=ttyS0 */
+#  ifdef CONFIG_16550_UART
+#    define TTYS1_DEV     g_uart0port     /* UART2=ttyS0;UART0=ttyS1 */
+#    ifdef CONFIG_16550_UART1
+#      define TTYS2_DEV   g_uart1port     /* UART2=ttyS0;UART0=ttyS1;UART1=ttyS2 */
+#      ifdef CONFIG_16550_UART3
+#        define TTYS3_DEV g_uart3port     /* UART2=ttyS0;UART0=ttyS1;UART1=ttyS2;UART3=ttyS3 */
+#      else
+#        undef TTYS3_DEV                  /* UART2=ttyS0;UART0=ttyS1;UART1=ttyS;No ttyS3 */
+#      endif
+#    else
+#      ifdef CONFIG_16550_UART3
+#        define TTYS2_DEV g_uart3port     /* UART2=ttyS0;UART0=ttyS1;UART3=ttys2;No ttyS3 */
+#      else
+#        undef TTYS2_DEV                  /* UART2=ttyS0;UART0=ttyS1;No ttyS2;No ttyS3 */
+#      endif
+#      undef TTYS3_DEV                    /* No ttyS3 */
+#    endif
+#  else
+#    ifdef CONFIG_16550_UART1
+#      define TTYS1_DEV   g_uart1port    /* UART2=ttyS0;UART1=ttyS1 */
+#      ifdef CONFIG_16550_UART3
+#        define TTYS2_DEV g_uart3port    /* UART2=ttyS0;UART1=ttyS1;UART3=ttyS2 */
+#      else
+#        undef TTYS2_DEV                 /* UART2=ttyS0;UART1=ttyS1;No ttyS2;No ttyS3 */
+#      endif
+#      undef TTYS3_DEV                   /* No ttyS3 */
+#    else
+#      ifdef CONFIG_16550_UART3
+#        define TTYS1_DEV g_uart3port    /* UART2=ttyS0;UART3=ttyS1;No ttyS3 */
+#      else
+#        undef TTYS1_DEV                 /* UART2=ttyS0;No ttyS1;No ttyS2;No ttyS3 */
+#      endif
+#      undef TTYS2_DEV                   /* No ttyS2 */
+#      undef TTYS3_DEV                   /* No ttyS3 */
+#    endif
+#  endif
+#elif defined(CONFIG_UART3_SERIAL_CONSOLE)
+#  define CONSOLE_DEV     g_uart3port    /* UART3=console */
+#  define TTYS0_DEV       g_uart3port    /* UART3=ttyS0 */
+#  ifdef CONFIG_16550_UART
+#    define TTYS1_DEV     g_uart0port    /* UART3=ttyS0;UART0=ttyS1 */
+#    ifdef CONFIG_16550_UART1
+#      define TTYS2_DEV   g_uart1port    /* UART3=ttyS0;UART0=ttyS1;UART1=ttyS2 */
+#      ifdef CONFIG_16550_UART2
+#        define TTYS3_DEV g_uart2port    /* UART3=ttyS0;UART0=ttyS1;UART1=ttyS2;UART2=ttyS3 */
+#      else
+#        undef TTYS3_DEV                 /* UART3=ttyS0;UART0=ttyS1;UART1=ttyS;No ttyS3 */
+#      endif
+#    else
+#      ifdef CONFIG_16550_UART2
+#        define TTYS2_DEV g_uart2port    /* UART3=ttyS0;UART0=ttyS1;UART2=ttys2;No ttyS3 */
+#      else
+#        undef TTYS2_DEV                 /* UART3=ttyS0;UART0=ttyS1;No ttyS2;No ttyS3 */
+#      endif
+#        undef TTYS3_DEV                 /* No ttyS3 */
+#    endif
+#  else
+#    ifdef CONFIG_16550_UART1
+#      define TTYS1_DEV   g_uart1port    /* UART3=ttyS0;UART1=ttyS1 */
+#      ifdef CONFIG_16550_UART2
+#        define TTYS2_DEV g_uart2port    /* UART3=ttyS0;UART1=ttyS1;UART2=ttyS2;No ttyS3 */
+#      else
+#        undef TTYS2_DEV                 /* UART3=ttyS0;UART1=ttyS1;No ttyS2;No ttyS3 */
+#      endif
+#      undef TTYS3_DEV                   /* No ttyS3 */
+#    else
+#      ifdef CONFIG_16550_UART2
+#        define TTYS1_DEV   g_uart2port  /* UART3=ttyS0;UART2=ttyS1;No ttyS3;No ttyS3 */
+#        undef TTYS3_DEV                 /* UART3=ttyS0;UART2=ttyS1;No ttyS2;No ttyS3 */
+#      else
+#        undef TTYS1_DEV                 /* UART3=ttyS0;No ttyS1;No ttyS2;No ttyS3 */
+#      endif
+#      undef TTYS2_DEV                   /* No ttyS2 */
+#      undef TTYS3_DEV                   /* No ttyS3 */
+#    endif
+#  endif
+#endif
+
+/************************************************************************************
+ * Inline Functions
+ ************************************************************************************/
+
+/****************************************************************************
+ * Name: uart_serialin
+ ****************************************************************************/
+
+static inline uart_datawidth_t uart_serialin(struct uart_16550_s *priv, int offset)
+{
+  return uart_getreg(priv->uartbase, offset);
+}
+
+/****************************************************************************
+ * Name: uart_serialout
+ ****************************************************************************/
+
+static inline void uart_serialout(struct uart_16550_s *priv, int offset, uart_datawidth_t value)
+{
+  uart_putreg(priv->uartbase, offset, value);
+}
+
+/****************************************************************************
+ * Name: uart_disableuartint
+ ****************************************************************************/
+
+static inline void uart_disableuartint(struct uart_16550_s *priv, uart_datawidth_t *ier)
+{
+  if (ier)
+    {
+      *ier = priv->ier & UART_IER_ALLIE;
+    }
+
+  priv->ier &= ~UART_IER_ALLIE;
+  uart_serialout(priv, UART_IER_OFFSET, priv->ier);
+}
+
+/****************************************************************************
+ * Name: uart_restoreuartint
+ ****************************************************************************/
+
+static inline void uart_restoreuartint(struct uart_16550_s *priv, uint32_t ier)
+{
+  priv->ier |= ier & UART_IER_ALLIE;
+  uart_serialout(priv, UART_IER_OFFSET, priv->ier);
+}
+
+/****************************************************************************
+ * Name: uart_enablebreaks
+ ****************************************************************************/
+
+static inline void uart_enablebreaks(struct uart_16550_s *priv, bool enable)
+{
+  uint32_t lcr = uart_serialin(priv, UART_LCR_OFFSET);
+  if (enable)
+    {
+      lcr |= UART_LCR_BRK;
+    }
+  else
+    {
+      lcr &= ~UART_LCR_BRK;
+    }
+  uart_serialout(priv, UART_LCR_OFFSET, lcr);
+}
+
+/************************************************************************************
+ * Name: uart_divisor
+ *
+ * Descrption:
+ *   Select a divider to produce the BAUD from the UART_CLK.
+ *
+ *     BAUD = UART_CLK / (16 * DL), or
+ *     DIV  = UART_CLK / BAUD / 16
+ *
+ *   Ignoring the fractional divider for now.
+ *
+ ************************************************************************************/
+
+static inline uint32_t uart_divisor(struct uart_16550_s *priv)
+{
+  return (priv->uartclk + (priv->baud << 3)) / (priv->baurd << 4);
+}
+
+/****************************************************************************
+ * Private Functions
+ ****************************************************************************/
+
+/****************************************************************************
+ * Name: uart_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 uart_setup(struct uart_dev_s *dev)
+{
+#ifndef CONFIG_16550_SUPRESS_CONFIG
+  struct uart_16550_s *priv = (struct uart_16550_s*)dev->priv;
+  uint16_t div;
+  uint32_t lcr;
+
+  /* Clear fifos */
+
+  uart_serialout(priv, UART_FCR_OFFSET, (UART_FCR_RXRST|UART_FCR_TXRST));
+
+  /* Set trigger */
+
+  uart_serialout(priv, UART_FCR_OFFSET, (UART_FCR_FIFOEN|UART_FCR_RXTRIGGER_8));
+
+  /* Set up the IER */
+
+  priv->ier = uart_serialin(priv, UART_IER_OFFSET);
+
+  /* Set up the LCR */
+
+  lcr = 0;
+  switch (priv->bits)
+    {
+      case 5 :
+        lcr |= UART_LCR_WLS_7BIT;
+        break;
+
+      case 6 :
+        lcr |= UART_LCR_WLS_7BIT;
+        break;
+
+      case 7 :
+        lcr |= UART_LCR_WLS_7BIT;
+        break;
+
+      default:
+      case 8 :
+        lcr |= UART_LCR_WLS_7BIT;
+        break;
+    }
+
+  if (priv->stopbits2)
+    {
+      lcr |= UART_LCR_STB;
+    }
+
+  if (priv->parity == 1)
+    {
+      lcr |= UART_LCR_PEN;
+    }
+  else if (priv->parity == 2)
+    {
+      lcr |= (UART_LCR_PEN|UART_LCR_EPS);
+    }
+
+  /* Enter DLAB=1 */
+
+  uart_serialout(priv, UART_LCR_OFFSET, (lcr | UART_LCR_DLAB));
+
+  /* Set the BAUD divisor */
+
+  div = uart_divisor(priv);
+  uart_serialout(priv, UART_DLM_OFFSET, div >> 8);
+  uart_serialout(priv, UART_DLL_OFFSET, div & 0xff);
+
+  /* Clear DLAB */
+
+  uart_serialout(priv, UART_LCR_OFFSET, lcr);
+
+  /* Configure the FIFOs */
+
+  uart_serialout(priv, UART_FCR_OFFSET,
+               (UART_FCR_RXTRIGGER_8|UART_FCR_TXRST|UART_FCR_RXRST|UART_FCR_FIFOEN));
+#endif
+  return OK;
+}
+
+/****************************************************************************
+ * Name: uart_shutdown
+ *
+ * Description:
+ *   Disable the UART.  This method is called when the serial
+ *   port is closed
+ *
+ ****************************************************************************/
+
+static void uart_shutdown(struct uart_dev_s *dev)
+{
+  struct uart_16550_s *priv = (struct uart_16550_s*)dev->priv;
+  uart_disableuartint(priv, NULL);
+}
+
+/****************************************************************************
+ * Name: uart_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 uart_attach(struct uart_dev_s *dev)
+{
+  struct uart_16550_s *priv = (struct uart_16550_s*)dev->priv;
+  int ret;
+
+  /* Attach and enable the IRQ */
+
+  ret = irq_attach(priv->irq, uart_interrupt);
+#ifndef CONFIG_ARCH_NOINTC
+  if (ret == OK)
+    {
+       /* Enable the interrupt (RX and TX interrupts are still disabled
+        * in the UART
+        */
+
+       uart_enable_irq(priv->irq);
+    }
+endif
+  return ret;
+}
+
+/****************************************************************************
+ * Name: uart_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 uart_detach(struct uart_dev_s *dev)
+{
+  struct uart_16550_s *priv = (struct uart_16550_s*)dev->priv;
+#ifndef CONFIG_ARCH_NOINTC
+  uart_disable_irq(priv->irq);
+#endif
+  irq_detach(priv->irq);
+}
+
+/****************************************************************************
+ * Name: uart_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_16550_s structure in order to call these functions.
+ *
+ ****************************************************************************/
+
+static int uart_interrupt(int irq, void *context)
+{
+  struct uart_dev_s   *dev = NULL;
+  struct uart_16550_s *priv;
+  uint32_t             status;
+  int                  passes;
+
+#ifdef CONFIG_16550_UART0
+  if (g_uart0priv.irq == irq)
+    {
+      dev = &g_uart0port;
+    }
+  else
+#endif
+#ifdef CONFIG_16550_UART1
+  if (g_uart1priv.irq == irq)
+    {
+      dev = &g_uart1port;
+    }
+  else
+#endif
+#ifdef CONFIG_16550_UART2
+  if (g_uart2priv.irq == irq)
+    {
+      dev = &g_uart2port;
+    }
+  else
+#endif
+#ifdef CONFIG_16550_UART3
+  if (g_uart3priv.irq == irq)
+    {
+      dev = &g_uart3port;
+    }
+  else
+#endif
+    {
+      PANIC(OSERR_INTERNAL);
+    }
+  priv = (struct uart_16550_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 status and check for loop
+       * termination conditions
+       */
+
+       status = uart_serialin(priv, UART_IIR_OFFSET);
+
+      /* The UART_IIR_INTSTATUS bit should be zero if there are pending
+       * interrupts
+       */
+
+      if ((status & UART_IIR_INTSTATUS) != 0)
+        {
+          /* Break out of the loop when there is no longer a
+           * pending interrupt
+           */
+
+          break;
+        }
+
+      /* Handle the interrupt by its interrupt ID field */
+
+      switch (status & UART_IIR_INTID_MASK)
+        {
+          /* Handle incoming, receive bytes (with or without timeout) */
+
+          case UART_IIR_INTID_RDA:
+          case UART_IIR_INTID_CTI:
+            {
+              uart_recvchars(dev);
+              break;
+            }
+
+          /* Handle outgoing, transmit bytes */
+
+          case UART_IIR_INTID_THRE:
+            {
+              uart_xmitchars(dev);
+              break;
+            }
+
+          /* Just clear modem status interrupts (UART1 only) */
+
+          case UART_IIR_INTID_MSI:
+            {
+              /* Read the modem status register (MSR) to clear */
+
+              status = uart_serialin(priv, UART_MSR_OFFSET);
+              vdbg("MSR: %02x\n", status);
+              break;
+            }
+
+          /* Just clear any line status interrupts */
+
+          case UART_IIR_INTID_RLS:
+            {
+              /* Read the line status register (LSR) to clear */
+
+              status = uart_serialin(priv, UART_LSR_OFFSET);
+              vdbg("LSR: %02x\n", status);
+              break;
+            }
+
+          /* There should be no other values */
+
+          default:
+            {
+              dbg("Unexpected IIR: %02x\n", status);
+              break;
+            }
+        }
+    }
+    return OK;
+}
+
+/****************************************************************************
+ * Name: uart_ioctl
+ *
+ * Description:
+ *   All ioctl calls will be routed through this method
+ *
+ ****************************************************************************/
+
+static int uart_ioctl(struct file *filep, int cmd, unsigned long arg)
+{
+  struct inode        *inode = filep->f_inode;
+  struct uart_dev_s   *dev   = inode->i_private;
+  struct uart_16550_s *priv  = (struct uart_16550_s*)dev->priv;
+  int                  ret    = OK;
+
+  switch (cmd)
+    {
+    case TIOCSERGSTRUCT:
+      {
+         struct uart_16550_s *user = (struct uart_16550_s*)arg;
+         if (!user)
+           {
+             *get_errno_ptr() = EINVAL;
+             ret = ERROR;
+           }
+         else
+           {
+             memcpy(user, dev, sizeof(struct uart_16550_s));
+           }
+       }
+       break;
+
+    case TIOCSBRK:  /* BSD compatibility: Turn break on, unconditionally */
+      {
+        irqstate_t flags = irqsave();
+        uart_enablebreaks(priv, true);
+        irqrestore(flags);
+      }
+      break;
+
+    case TIOCCBRK:  /* BSD compatibility: Turn break off, unconditionally */
+      {
+        irqstate_t flags;
+        flags = irqsave();
+        uart_enablebreaks(priv, false);
+        irqrestore(flags);
+      }
+      break;
+
+    default:
+      *get_errno_ptr() = ENOTTY;
+      ret = ERROR;
+      break;
+    }
+
+  return ret;
+}
+
+/****************************************************************************
+ * Name: uart_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 uart_receive(struct uart_dev_s *dev, uint32_t *status)
+{
+  struct uart_16550_s *priv = (struct uart_16550_s*)dev->priv;
+  uint32_t rbr;
+
+  *status = uart_serialin(priv, UART_LSR_OFFSET);
+  rbr     = uart_serialin(priv, UART_RBR_OFFSET);
+  return rbr;
+}
+
+/****************************************************************************
+ * Name: uart_rxint
+ *
+ * Description:
+ *   Call to enable or disable RX interrupts
+ *
+ ****************************************************************************/
+
+static void uart_rxint(struct uart_dev_s *dev, bool enable)
+{
+  struct uart_16550_s *priv = (struct uart_16550_s*)dev->priv;
+  if (enable)
+    {
+#ifndef CONFIG_SUPPRESS_SERIAL_INTS
+      priv->ier |= UART_IER_ERBFI;
+#endif
+    }
+  else
+    {
+      priv->ier &= ~UART_IER_ERBFI;
+    }
+  uart_serialout(priv, UART_IER_OFFSET, priv->ier);
+}
+
+/****************************************************************************
+ * Name: uart_rxavailable
+ *
+ * Description:
+ *   Return true if the receive fifo is not empty
+ *
+ ****************************************************************************/
+
+static bool uart_rxavailable(struct uart_dev_s *dev)
+{
+  struct uart_16550_s *priv = (struct uart_16550_s*)dev->priv;
+  return ((uart_serialin(priv, UART_LSR_OFFSET) & UART_LSR_RDR) != 0);
+}
+
+/****************************************************************************
+ * Name: uart_send
+ *
+ * Description:
+ *   This method will send one byte on the UART
+ *
+ ****************************************************************************/
+
+static void uart_send(struct uart_dev_s *dev, int ch)
+{
+  struct uart_16550_s *priv = (struct uart_16550_s*)dev->priv;
+  uart_serialout(priv, UART_THR_OFFSET, (uint32_t)ch);
+}
+
+/****************************************************************************
+ * Name: uart_txint
+ *
+ * Description:
+ *   Call to enable or disable TX interrupts
+ *
+ ****************************************************************************/
+
+static void uart_txint(struct uart_dev_s *dev, bool enable)
+{
+  struct uart_16550_s *priv = (struct uart_16550_s*)dev->priv;
+  irqstate_t flags;
+
+  flags = irqsave();
+  if (enable)
+    {
+#ifndef CONFIG_SUPPRESS_SERIAL_INTS
+      priv->ier |= UART_IER_ETBEI;
+      uart_serialout(priv, 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_ETBEI;
+      uart_serialout(priv, UART_IER_OFFSET, priv->ier);
+    }
+  irqrestore(flags);
+}
+
+/****************************************************************************
+ * Name: uart_txready
+ *
+ * Description:
+ *   Return true if the tranmsit fifo is not full
+ *
+ ****************************************************************************/
+
+static bool uart_txready(struct uart_dev_s *dev)
+{
+  struct uart_16550_s *priv = (struct uart_16550_s*)dev->priv;
+  return ((uart_serialin(priv, UART_LSR_OFFSET) & UART_LSR_THRE) != 0);
+}
+
+/****************************************************************************
+ * Name: uart_txempty
+ *
+ * Description:
+ *   Return true if the transmit fifo is empty
+ *
+ ****************************************************************************/
+
+static bool uart_txempty(struct uart_dev_s *dev)
+{
+  struct uart_16550_s *priv = (struct uart_16550_s*)dev->priv;
+  return ((uart_serialin(priv, UART_LSR_OFFSET) & UART_LSR_THRE) != 0);
+}
+
+/****************************************************************************
+ * Public Funtions
+ ****************************************************************************/
+
+/****************************************************************************
+ * Name: uart_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 uart_serialinit.
+ *
+ *   NOTE: Configuration of the CONSOLE UART was performed by uart_lowsetup()
+ *   very early in the boot sequence.
+ *
+ ****************************************************************************/
+
+void uart_earlyserialinit(void)
+{
+  /* Configure all UARTs (except the CONSOLE UART) and disable interrupts */
+
+#ifdef CONFIG_16550_UART0
+  uart_disableuartint(&g_uart0priv, NULL);
+#endif
+#ifdef CONFIG_16550_UART1
+  uart_disableuartint(&g_uart1priv, NULL);
+#endif
+  uart_disableuartint(&g_uart2priv, NULL);
+#endif
+  uart_disableuartint(&g_uart3priv, NULL);
+#endif
+
+  /* Configuration whichever one is the console */
+
+#ifdef CONSOLE_DEV
+  CONSOLE_DEV.isconsole = true;
+  uart_setup(&CONSOLE_DEV);
+#endif
+}
+
+/****************************************************************************
+ * Name: uart_serialinit
+ *
+ * Description:
+ *   Register serial console and serial ports.  This assumes that
+ *   uart_earlyserialinit was called previously.
+ *
+ ****************************************************************************/
+
+void uart_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
+#ifdef TTYS3_DEV
+  (void)uart_register("/dev/ttyS3", &TTYS3_DEV);
+#endif
+}
+
+/****************************************************************************
+ * Name: uart_putc
+ *
+ * Description:
+ *   Provide priority, low-level access to support OS debug  writes
+ *
+ ****************************************************************************/
+
+#ifdef HAVE_16550_CONSOLE
+int uart_putc(int ch)
+{
+  struct uart_16550_s *priv = (struct uart_16550_s*)CONSOLE_DEV.priv;
+  uart_datawidth_t ier;
+
+  uart_disableuartint(priv, &ier);
+
+  /* Check for LF */
+
+  if (ch == '\n')
+    {
+      /* Add CR */
+
+      uart_lowputc('\r');
+    }
+
+  uart_lowputc(ch);
+  uart_restoreuartint(priv, ier);
+  return ch;
+}
+#endif
+
+#endif /* CONFIG_UART_16550 */