ADC bugfixes plus new DAC logic from Lzyy

git-svn-id: svn://svn.code.sf.net/p/nuttx/code/trunk@3913 42af7a65-404d-4744-a932-0658087f49c3

5 files changed, 730 insertions, 20 deletions

diff --git a/nuttx/drivers/analog/Make.defs b/nuttx/drivers/analog/Make.defs
index 4702fc8d8..ed09c709a 100644
--- a/nuttx/drivers/analog/Make.defs
+++ b/nuttx/drivers/analog/Make.defs
@@ -41,8 +41,13 @@ ifeq ($(CONFIG_DAC),y)
 
 # Include the common ADC character driver
 
+CSRCS += dac.c
+
 # Include DAC device drivers
 
+ifeq ($(CONFIG_DAC_AD5410),y)
+  CSRCS += ad5410.c
+endif
 endif
 
 # Check for ADC devices
diff --git a/nuttx/drivers/analog/ad5410.c b/nuttx/drivers/analog/ad5410.c
new file mode 100644
index 000000000..65e4adf7d
--- /dev/null
+++ b/nuttx/drivers/analog/ad5410.c
@@ -0,0 +1,206 @@
+/************************************************************************************
+ * arch/drivers/analog/ad5410.c
+ *
+ *   Copyright (C) 2011 Li Zhuoyi. All rights reserved.
+ *   Author: Li Zhuoyi <lzyy.cn@gmail.com>
+ *   History: 0.1 2011-08-05 initial version
+ * 
+ * This file is a part of NuttX:
+ *
+ *   Copyright (C) 2010 Gregory Nutt. All rights reserved.
+ *
+ * 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.
+ *
+ ************************************************************************************/
+
+#include <nuttx/config.h>
+
+#include <stdio.h>
+#include <sys/types.h>
+#include <stdint.h>
+#include <stdbool.h>
+#include <semaphore.h>
+#include <errno.h>
+#include <debug.h>
+
+#include <arch/board/board.h>
+#include <nuttx/arch.h>
+#include <nuttx/analog/dac.h>
+#include <nuttx/spi.h>
+#include "lpc17_internal.h"
+
+#if defined(CONFIG_DAC_AD5410)
+
+#define AD5410_REG_NOP    0x00
+#define AD5410_REG_WR     0x01
+#define AD5410_REG_RD     0x02
+#define AD5410_REG_CMD    0x55
+#define AD5410_REG_RST    0x56
+
+#define AD5410_CMD_REXT       (1<<13)
+#define AD5410_CMD_OUTEN      (1<<12)
+#define AD5410_CMD_SRCLK(x)   (x<<8)  
+#define AD5410_CMD_SRSTEP(x)  (x<<5)
+#define AD5410_CMD_SREN       (1<<4)
+#define AD5410_CMD_DCEN       (1<<3)
+#define AD5410_CMD_420MA      0x05
+#define AD5410_CMD_020MA      0x06
+#define AD5410_CMD_024MA      0x07
+
+/****************************************************************************
+ * ad_private Types
+ ****************************************************************************/
+struct up_dev_s
+{
+    int devno;
+    FAR struct spi_dev_s  *spi;      /* Cached SPI device reference */
+};
+
+/****************************************************************************
+ * ad_private Function Prototypes
+ ****************************************************************************/
+
+/* DAC methods */
+
+static void dac_reset(FAR struct dac_dev_s *dev);
+static int  dac_setup(FAR struct dac_dev_s *dev);
+static void dac_shutdown(FAR struct dac_dev_s *dev);
+static void dac_txint(FAR struct dac_dev_s *dev, bool enable);
+static int  dac_send(FAR struct dac_dev_s *dev, FAR struct dac_msg_s *msg);
+static int  dac_ioctl(FAR struct dac_dev_s *dev, int cmd, unsigned long arg);
+static int  dac_interrupt(int irq, void *context);
+
+/****************************************************************************
+ * ad_private Data
+ ****************************************************************************/
+
+static const struct dac_ops_s g_dacops =
+{
+    .ao_reset =dac_reset,
+    .ao_setup = dac_setup,
+    .ao_shutdown = dac_shutdown,
+    .ao_txint = dac_txint,
+    .ao_send = dac_send,
+    .ao_ioctl = dac_ioctl,
+};
+
+static struct up_dev_s g_dacpriv;
+static struct dac_dev_s g_dacdev =
+{
+    .ad_ops = &g_dacops,
+	.ad_priv= &g_dacpriv,
+};
+
+/****************************************************************************
+ * ad_private Functions
+ ****************************************************************************/
+
+/* Reset the DAC device.  Called early to initialize the hardware. This
+* is called, before ao_setup() and on error conditions.
+*/
+static void dac_reset(FAR struct dac_dev_s *dev)
+{
+
+}
+
+/* Configure the DAC. This method is called the first time that the DAC
+* device is opened.  This will occur when the port is first opened.
+* This setup includes configuring and attaching DAC interrupts.  Interrupts
+* are all disabled upon return.
+*/
+static int  dac_setup(FAR struct dac_dev_s *dev)
+{
+    FAR struct up_dev_s *priv = (FAR struct up_dev_s *)dev->ad_priv;
+    FAR struct spi_dev_s *spi = priv->spi;
+	SPI_SELECT(spi, priv->devno, true);
+	SPI_SEND(spi,AD5410_REG_CMD);
+	SPI_SEND(spi,(AD5410_CMD_OUTEN|AD5410_CMD_420MA)>>8);
+	SPI_SEND(spi,AD5410_CMD_OUTEN|AD5410_CMD_420MA);
+	SPI_SELECT(spi, priv->devno, false);
+    return OK;
+}
+
+/* Disable the DAC.  This method is called when the DAC device is closed.
+* This method reverses the operation the setup method.
+*/
+static void dac_shutdown(FAR struct dac_dev_s *dev)
+{
+}
+
+/* Call to enable or disable TX interrupts */
+static void dac_txint(FAR struct dac_dev_s *dev, bool enable)
+{
+}
+
+static int  dac_send(FAR struct dac_dev_s *dev, FAR struct dac_msg_s *msg)
+{
+    FAR struct up_dev_s *priv = (FAR struct up_dev_s *)dev->ad_priv;
+    FAR struct spi_dev_s *spi = priv->spi;
+	SPI_SELECT(spi, priv->devno, true);
+	SPI_SEND(spi,AD5410_REG_WR);
+	SPI_SEND(spi,(uint8_t)(msg->am_data>>24));
+	SPI_SEND(spi,(uint8_t)(msg->am_data>>16));
+	SPI_SELECT(spi, priv->devno, false);
+	dac_txdone(&g_dacdev);
+	return 0;
+}
+
+/* All ioctl calls will be routed through this method */
+static int  dac_ioctl(FAR struct dac_dev_s *dev, int cmd, unsigned long arg)
+{
+    dbg("Fix me:Not Implemented\n");
+    return 0;
+}
+
+/****************************************************************************
+ * Public Functions
+ ****************************************************************************/
+
+/****************************************************************************
+ * Name: up_ad5410cinitialize
+ *
+ * Description:
+ *   Initialize the selected DAC port
+ *
+ * Input Parameter:
+ *   Port number (for hardware that has mutiple DAC interfaces)
+ *
+ * Returned Value:
+ *   Valid ad5410 device structure reference on succcess; a NULL on failure
+ *
+ ****************************************************************************/
+
+FAR struct dac_dev_s *up_ad5410initialize(FAR struct spi_dev_s *spi, unsigned int devno)
+{
+    FAR struct up_dev_s *priv = (FAR struct up_dev_s *)g_dacdev.ad_priv;
+	priv->spi=spi;
+	priv->devno=devno;
+	return &g_dacdev;
+}
+#endif
+
diff --git a/nuttx/drivers/analog/adc.c b/nuttx/drivers/analog/adc.c
index 664bd5461..bf3d7bdf6 100644
--- a/nuttx/drivers/analog/adc.c
+++ b/nuttx/drivers/analog/adc.c
@@ -1,5 +1,5 @@
 /****************************************************************************
- * drivers/adc/adc.c
+ * drivers/analog/adc.c
  *
  *   Copyright (C) 2011 Li Zhuoyi. All rights reserved.
  *   Author: Li Zhuoyi <lzyy.cn@gmail.com>
diff --git a/nuttx/drivers/analog/ads1255.c b/nuttx/drivers/analog/ads1255.c
index adc053a93..374decc54 100644
--- a/nuttx/drivers/analog/ads1255.c
+++ b/nuttx/drivers/analog/ads1255.c
@@ -1,9 +1,10 @@
 /************************************************************************************
- * arch/drivers/adc/ads1255.c
+ * arch/drivers/analog/ads1255.c
  *
  *   Copyright (C) 2011 Li Zhuoyi. All rights reserved.
  *   Author: Li Zhuoyi <lzyy.cn@gmail.com>
  *   History: 0.1 2011-08-05 initial version
+ *            0.2 2011-08-25 fix bug in g_adcdev (cd_ops -> ad_ops,cd_priv -> ad_priv) 
  *
  * This file is a part of NuttX:
  *
@@ -101,13 +102,13 @@
 #endif
 
 /****************************************************************************
- * cd_private Types
+ * ad_private Types
  ****************************************************************************/
 
 struct up_dev_s
 {
     uint8_t channel;
-    uint8_t sps;
+    uint32_t sps;
     uint8_t pga;
     uint8_t buf;
     const uint8_t *mux;
@@ -117,7 +118,7 @@ struct up_dev_s
 };
 
 /****************************************************************************
- * cd_private Function Prototypes
+ * ad_private Function Prototypes
  ****************************************************************************/
 
 /* ADC methods */
@@ -130,16 +131,16 @@ static int  adc_ioctl(FAR struct adc_dev_s *dev, int cmd, unsigned long arg);
 static int  adc_interrupt(int irq, void *context);
 
 /****************************************************************************
- * cd_private Data
+ * ad_private Data
  ****************************************************************************/
 
 static const struct adc_ops_s g_adcops =
 {
-    adc_reset,     /* ao_reset */
-    adc_setup,     /* ao_setup */
-    adc_shutdown,  /* ao_shutdown */
-    adc_rxint,     /* ao_rxint */
-    adc_ioctl      /* ao_read */
+    .ao_reset = adc_reset,     /* ao_reset */
+    .ao_setup = adc_setup,     /* ao_setup */
+    .ao_shutdown = adc_shutdown,  /* ao_shutdown */
+    .ao_rxint = adc_rxint,     /* ao_rxint */
+    .ao_ioctl = adc_ioctl      /* ao_read */
 };
 
 static struct up_dev_s g_adcpriv =
@@ -155,8 +156,8 @@ static struct up_dev_s g_adcpriv =
 
 static struct adc_dev_s g_adcdev =
 {
-    .cd_ops = &g_adcops,
-    .cd_priv= &g_adcpriv,
+    .ad_ops = &g_adcops,
+    .ad_priv= &g_adcpriv,
 };
 
 /****************************************************************************
@@ -183,7 +184,7 @@ static uint8_t getspsreg(uint16_t sps)
 }
 
 /****************************************************************************
- * cd_private Functions
+ * ad_private Functions
  ****************************************************************************/
 /* Reset the ADC device.  Called early to initialize the hardware. This
 * is called, before ao_setup() and on error conditions.
@@ -191,7 +192,7 @@ static uint8_t getspsreg(uint16_t sps)
 
 static void adc_reset(FAR struct adc_dev_s *dev)
 {
-    FAR struct up_dev_s *priv = (FAR struct up_dev_s *)dev->cd_priv;
+    FAR struct up_dev_s *priv = (FAR struct up_dev_s *)dev->ad_priv;
     FAR struct spi_dev_s *spi = priv->spi;
 
     SPI_SETMODE(spi, SPIDEV_MODE1);
@@ -213,7 +214,7 @@ static void adc_reset(FAR struct adc_dev_s *dev)
 
 static int  adc_setup(FAR struct adc_dev_s *dev)
 {
-    FAR struct up_dev_s *priv = (FAR struct up_dev_s *)dev->cd_priv;
+    FAR struct up_dev_s *priv = (FAR struct up_dev_s *)dev->ad_priv;
     FAR struct spi_dev_s *spi = priv->spi;
     int ret = irq_attach(priv->irq, adc_interrupt);
     if (ret == OK)
@@ -242,7 +243,7 @@ static int  adc_setup(FAR struct adc_dev_s *dev)
 
 static void adc_shutdown(FAR struct adc_dev_s *dev)
 {
-    FAR struct up_dev_s *priv = (FAR struct up_dev_s *)dev->cd_priv;
+    FAR struct up_dev_s *priv = (FAR struct up_dev_s *)dev->ad_priv;
     up_disable_irq(priv->irq);
     irq_detach(priv->irq);
 }
@@ -251,7 +252,7 @@ static void adc_shutdown(FAR struct adc_dev_s *dev)
 
 static void adc_rxint(FAR struct adc_dev_s *dev, bool enable)
 {
-    FAR struct up_dev_s *priv = (FAR struct up_dev_s *)dev->cd_priv;
+    FAR struct up_dev_s *priv = (FAR struct up_dev_s *)dev->ad_priv;
     if (enable)
         up_enable_irq(priv->irq);
     else
@@ -269,7 +270,7 @@ static int  adc_ioctl(FAR struct adc_dev_s *dev, int cmd, unsigned long arg)
 static int adc_interrupt(int irq, void *context)
 {
     uint32_t regval;
-    FAR struct up_dev_s *priv = (FAR struct up_dev_s *)g_adcdev.cd_priv;
+    FAR struct up_dev_s *priv = (FAR struct up_dev_s *)g_adcdev.ad_priv;
     FAR struct spi_dev_s *spi = priv->spi;
     unsigned char buf[4];
     unsigned char ch;
@@ -322,7 +323,7 @@ static int adc_interrupt(int irq, void *context)
 
 FAR struct adc_dev_s *up_ads1255initialize(FAR struct spi_dev_s *spi, unsigned int devno)
 {
-    FAR struct up_dev_s *priv = (FAR struct up_dev_s *)g_adcdev.cd_priv;
+    FAR struct up_dev_s *priv = (FAR struct up_dev_s *)g_adcdev.ad_priv;
 
     /* Driver state data */
 
diff --git a/nuttx/drivers/analog/dac.c b/nuttx/drivers/analog/dac.c
new file mode 100644
index 000000000..a5f4c1473
--- /dev/null
+++ b/nuttx/drivers/analog/dac.c
@@ -0,0 +1,498 @@
+/****************************************************************************
+ * drivers/analog/dac.c
+ *
+ *   Copyright (C) 2011 Li Zhuoyi. All rights reserved.
+ *   Author: Li Zhuoyi <lzyy.cn@gmail.com>
+ *   History: 0.1 2011-08-04 initial version
+ * 
+ * Derived from drivers/can.c
+ *
+ *   Copyright (C) 2008-2009Gregory 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 <string.h>
+#include <semaphore.h>
+#include <fcntl.h>
+#include <errno.h>
+#include <debug.h>
+
+#include <nuttx/fs.h>
+#include <nuttx/arch.h>
+#include <nuttx/analog/dac.h>
+
+#include <arch/irq.h>
+
+/****************************************************************************
+ * Pre-processor Definitions
+ ****************************************************************************/
+
+#define HALF_SECOND_MSEC 500
+#define HALF_SECOND_USEC 500000L
+
+
+/****************************************************************************
+ * Private Function Prototypes
+ ****************************************************************************/
+
+static int     dac_open(FAR struct file *filep);
+static int     dac_close(FAR struct file *filep);
+static ssize_t dac_read(FAR struct file *, FAR char *, size_t);
+static ssize_t dac_write(FAR struct file *filep, FAR const char *buffer, size_t buflen);
+static int     dac_ioctl(FAR struct file *filep,int cmd,unsigned long arg);
+
+/****************************************************************************
+ * Private Data
+ ****************************************************************************/
+
+static const struct file_operations dac_fops =
+{
+  dac_open,
+  dac_close,
+  dac_read,
+  dac_write,
+  0,
+  dac_ioctl
+#ifndef CONFIG_DISABLE_POLL
+  , 0
+#endif
+};
+
+/****************************************************************************
+ * Private Functions
+ ****************************************************************************/
+/************************************************************************************
+ * Name: dac_open
+ *
+ * Description:
+ *   This function is called whenever the DAC device is opened.
+ *
+ ************************************************************************************/
+
+static int dac_open(FAR struct file *filep)
+{
+  FAR struct inode     *inode = filep->f_inode;
+  FAR struct dac_dev_s *dev   = inode->i_private;
+  uint8_t               tmp;
+  int                   ret   = OK;
+
+  /* If the port is the middle of closing, wait until the close is finished */
+
+  if (sem_wait(&dev->ad_closesem) != OK)
+    {
+      ret = -errno;
+    }
+  else
+    {
+      /* Increment the count of references to the device.  If this the first
+       * time that the driver has been opened for this device, then initialize
+       * the device.
+       */
+
+      tmp = dev->ad_ocount + 1;
+      if (tmp == 0)
+        {
+          /* More than 255 opens; uint8_t overflows to zero */
+
+          ret = -EMFILE;
+        }
+      else
+        {
+          /* Check if this is the first time that the driver has been opened. */
+
+          if (tmp == 1)
+            {
+              /* Yes.. perform one time hardware initialization. */
+
+              irqstate_t flags = irqsave();
+              ret = dev->ad_ops->ao_setup(dev);
+              if (ret == OK)
+                {
+                  /* Mark the FIFOs empty */
+
+                  dev->ad_xmit.af_head = 0;
+                  dev->ad_xmit.af_tail = 0;
+
+                  /* Save the new open count on success */
+
+                  dev->ad_ocount = tmp;
+                }
+              irqrestore(flags);
+            }
+        }
+      sem_post(&dev->ad_closesem);
+    }
+  return ret;
+}
+
+/************************************************************************************
+ * Name: dac_close
+ *
+ * Description:
+ *   This routine is called when the DAC device is closed.
+ *   It waits for the last remaining data to be sent.
+ *
+ ************************************************************************************/
+
+static int dac_close(FAR struct file *filep)
+{
+  FAR struct inode     *inode = filep->f_inode;
+  FAR struct dac_dev_s *dev   = inode->i_private;
+  irqstate_t            flags;
+  int                   ret = OK;
+
+  if (sem_wait(&dev->ad_closesem) != OK)
+    {
+      ret = -errno;
+    }
+  else
+    {
+      /* Decrement the references to the driver.  If the reference count will
+       * decrement to 0, then uninitialize the driver.
+       */
+
+      if (dev->ad_ocount > 1)
+        {
+          dev->ad_ocount--;
+          sem_post(&dev->ad_closesem);
+        }
+      else
+        {
+          /* There are no more references to the port */
+
+          dev->ad_ocount = 0;
+
+          /* Now we wait for the transmit FIFO to clear */
+
+          while (dev->ad_xmit.af_head != dev->ad_xmit.af_tail)
+            {
+#ifndef CONFIG_DISABLE_SIGNALS
+               usleep(HALF_SECOND_USEC);
+#else
+               up_mdelay(HALF_SECOND_MSEC);
+#endif
+            }
+
+          /* Free the IRQ and disable the DAC device */
+
+          flags = irqsave();       /* Disable interrupts */
+          dev->ad_ops->ao_shutdown(dev);       /* Disable the DAC */
+          irqrestore(flags);
+
+          sem_post(&dev->ad_closesem);
+        }
+    }
+  return ret;
+}
+
+/****************************************************************************
+ * Name: dac_read
+ ****************************************************************************/
+
+static ssize_t dac_read(FAR struct file *filep, FAR char *buffer, size_t buflen)
+{
+  return 0;
+}
+
+/************************************************************************************
+ * Name: dac_xmit
+ *
+ * Description:
+ *   Send the message at the head of the ad_xmit FIFO
+ *
+ * Assumptions:
+ *   Called with interrupts disabled
+ *
+ ************************************************************************************/
+
+static int dac_xmit(FAR struct dac_dev_s *dev)
+{
+  bool enable = false;
+  int ret = OK;
+
+  /* Check if the xmit FIFO is empty */
+
+  if (dev->ad_xmit.af_head != dev->ad_xmit.af_tail)
+    {
+      /* Send the next message at the head of the FIFO */
+
+      ret = dev->ad_ops->ao_send(dev, &dev->ad_xmit.af_buffer[dev->ad_xmit.af_head]);
+
+      /* Make sure the TX done interrupts are enabled */
+
+      enable = (ret == OK ? true : false);
+    }
+  dev->ad_ops->ao_txint(dev, enable);
+  return ret;
+}
+
+/************************************************************************************
+ * Name: dac_write
+ ************************************************************************************/
+
+static ssize_t dac_write(FAR struct file *filep, FAR const char *buffer, size_t buflen)
+{
+  FAR struct inode      *inode = filep->f_inode;
+  FAR struct dac_dev_s  *dev   = inode->i_private;
+  FAR struct dac_fifo_s *fifo  = &dev->ad_xmit;
+  FAR struct dac_msg_s  *msg;
+  bool                   empty = false;
+  ssize_t                nsent = 0;
+  irqstate_t             flags;
+  int                    nexttail;
+  int                    msglen;
+  int                    ret   = 0;
+
+  /* Interrupts must disabled throughout the following */
+
+  flags = irqsave();
+
+  /* Check if the TX FIFO was empty when we started.  That is a clue that we have
+   * to kick off a new TX sequence.
+   */
+
+  empty = (fifo->af_head == fifo->af_tail);
+
+  /* Add the messages to the FIFO.  Ignore any trailing messages that are
+   * shorter than the minimum.
+   */
+
+  if (buflen % 5 ==0 )
+	msglen=5;
+  else if (buflen % 4 ==0 )
+	msglen=4;
+  else if (buflen % 3 ==0 )
+	msglen=3;
+  else if (buflen % 2 ==0 )
+	msglen=2;
+  else if (buflen == 1)
+	msglen=1;
+  else
+	msglen=5;
+
+  while ((buflen - nsent) >= msglen )
+    {
+      /* Check if adding this new message would over-run the drivers ability to enqueue
+       * xmit data.
+       */
+
+      nexttail = fifo->af_tail + 1;
+      if (nexttail >= CONFIG_DAC_FIFOSIZE)
+        {
+          nexttail = 0;
+        }
+
+      /* If the XMIT fifo becomes full, then wait for space to become available */
+
+      while (nexttail == fifo->af_head)
+        {
+          /* The transmit FIFO is full  -- was non-blocking mode selected? */
+
+          if (filep->f_oflags & O_NONBLOCK)
+            {
+              if (nsent == 0)
+                {
+                  ret = -EAGAIN;
+                }
+              else
+                {
+                  ret = nsent;
+                }
+              goto return_with_irqdisabled;
+            }
+
+          /* If the FIFO was empty when we started, then we will have
+           * start the XMIT sequence to clear the FIFO.
+           */
+
+          if (empty)
+            {
+              dac_xmit(dev);
+            }
+
+          /* Wait for a message to be sent */
+
+          do
+            {
+              ret = sem_wait(&fifo->af_sem);
+              if (ret < 0 && errno != EINTR)
+                {
+                  ret = -errno;
+                  goto return_with_irqdisabled;
+                }
+            }
+          while (ret < 0);
+
+          /* Re-check the FIFO state */
+
+          empty = (fifo->af_head == fifo->af_tail);
+        }
+
+      /* We get here if there is space at the end of the FIFO.  Add the new
+       * CAN message at the tail of the FIFO.
+       */
+	 if(msglen==5)
+     {
+		msg    = (FAR struct dac_msg_s *)&buffer[nsent];
+		memcpy(&fifo->af_buffer[fifo->af_tail], msg, msglen);
+     }
+     else if(msglen == 4)
+     {
+		 fifo->af_buffer[fifo->af_tail].am_channel=buffer[nsent];
+		 fifo->af_buffer[fifo->af_tail].am_data=*(uint32_t *)&buffer[nsent];
+		 fifo->af_buffer[fifo->af_tail].am_data&=0xffffff00;
+	 }
+     else if(msglen == 3)
+     {
+		 fifo->af_buffer[fifo->af_tail].am_channel=buffer[nsent];
+		 fifo->af_buffer[fifo->af_tail].am_data=(*(uint16_t *)&buffer[nsent+1]);
+		 fifo->af_buffer[fifo->af_tail].am_data<<=16;
+	 }
+     else if(msglen == 2)
+     {
+		 fifo->af_buffer[fifo->af_tail].am_channel=0;
+		 fifo->af_buffer[fifo->af_tail].am_data=(*(uint16_t *)&buffer[nsent]);
+		 fifo->af_buffer[fifo->af_tail].am_data<<=16;
+	 }
+     else if(msglen == 1)
+     {
+		 fifo->af_buffer[fifo->af_tail].am_channel=0;
+		 fifo->af_buffer[fifo->af_tail].am_data=buffer[nsent];
+		 fifo->af_buffer[fifo->af_tail].am_data<<=24;
+	 }
+      /* Increment the tail of the circular buffer */
+
+      fifo->af_tail = nexttail;
+
+      /* Increment the number of bytes that were sent */
+
+      nsent += msglen;
+    }
+
+ /* We get here after all messages have been added to the FIFO.  Check if
+  * we need to kick of the XMIT sequence.
+  */
+
+ if (empty)
+   {
+     dac_xmit(dev);
+   }
+
+  /* Return the number of bytes that were sent */
+
+  ret = nsent;
+
+return_with_irqdisabled:
+  irqrestore(flags);
+  return ret;
+}
+
+/************************************************************************************
+ * Name: dac_ioctl
+ ************************************************************************************/
+
+static int dac_ioctl(FAR struct file *filep, int cmd, unsigned long arg)
+{
+  FAR struct inode     *inode = filep->f_inode;
+  FAR struct dac_dev_s *dev   = inode->i_private;
+  int               ret   = OK;
+
+  ret = dev->ad_ops->ao_ioctl(dev, cmd, arg);
+  return ret;
+}
+
+/****************************************************************************
+ * Public Functions
+ ****************************************************************************/
+
+/************************************************************************************
+ * Name: dac_txdone
+ *
+ * Description:
+ *   Called from the DAC interrupt handler at the completion of a send operation.
+ *
+ * Return:
+ *   OK on success; a negated errno on failure.
+ *
+ ************************************************************************************/
+
+int dac_txdone(FAR struct dac_dev_s *dev)
+{
+  int ret = -ENOENT;
+
+  /* Verify that the xmit FIFO is not empty */
+
+  if (dev->ad_xmit.af_head != dev->ad_xmit.af_tail)
+    {
+      /* Remove the message at the head of the xmit FIFO */
+
+      if (++dev->ad_xmit.af_head >= CONFIG_DAC_FIFOSIZE)
+        {
+          dev->ad_xmit.af_head = 0;
+        }
+
+      /* Send the next message in the FIFO */
+
+      ret = dac_xmit(dev);
+      if (ret == OK)
+        {
+          /* Inform any waiting threads that new xmit space is available */
+
+          ret = sem_post(&dev->ad_xmit.af_sem);
+        }
+    }
+  return ret;
+}
+
+int dac_register(FAR const char *path, FAR struct dac_dev_s *dev)
+{
+  /* Initialize the DAC device structure */
+
+  dev->ad_ocount = 0;
+
+  sem_init(&dev->ad_xmit.af_sem, 0, 0);
+  sem_init(&dev->ad_closesem, 0, 1);
+
+  dev->ad_ops->ao_reset(dev);
+
+  return register_driver(path, &dac_fops, 0555, dev);
+}
+