SAMA5: Framework for an touchscreen driver (incomplete)

6 files changed, 1251 insertions, 29 deletions

diff --git a/nuttx/ChangeLog b/nuttx/ChangeLog
index 7e6487bab..ffb114cb6 100644
--- a/nuttx/ChangeLog
+++ b/nuttx/ChangeLog
@@ -5675,4 +5675,7 @@
 	* arch/arm/src/sama5/sam_adc.c and .h:  Framework for an ADC
 	  driver to come (just empty "skeleton" files on initial commit)
 	  (2013-9-30).
+	* arch/arm/src/sama5/sam_touchscreen.h and .h:  Framework for a
+	  touchscreen driver (also an empty "skeleton" file on the initial
+	  commit) (2013-9-30).
 
diff --git a/nuttx/arch/arm/src/sama5/chip/sam_adc.h b/nuttx/arch/arm/src/sama5/chip/sam_adc.h
index 495d6c0b6..b722533c4 100644
--- a/nuttx/arch/arm/src/sama5/chip/sam_adc.h
+++ b/nuttx/arch/arm/src/sama5/chip/sam_adc.h
@@ -48,6 +48,9 @@
 /****************************************************************************************
  * Pre-processor Definitions
  ****************************************************************************************/
+/* General definitions ******************************************************************/
+
+#define SAM_ADC_NCHANNELS          12     /* 12 ADC Channels */
 
 /* ADC register offsets ****************************************************************/
 
diff --git a/nuttx/arch/arm/src/sama5/sam_adc.c b/nuttx/arch/arm/src/sama5/sam_adc.c
index c34ff0ef4..4249a44ab 100644
--- a/nuttx/arch/arm/src/sama5/sam_adc.c
+++ b/nuttx/arch/arm/src/sama5/sam_adc.c
@@ -74,23 +74,42 @@
 
 struct sam_adc_s
 {
+  /* Debug stuff */
+
+#ifdef CONFIG_SAMA5_ADC_REGDEBUG
+   bool               wrlast;     /* Last was a write */
+   uintptr_t          addrlast;   /* Last address */
+   uint32_t           vallast;    /* Last value */
+   int                ntimes;     /* Number of times */
+#endif
 };
 
 /****************************************************************************
  * Private Function Prototypes
  ****************************************************************************/
+/* Register operations ******************************************************/
+
+#if defined(CONFIG_SAMA5_ADC_REGDEBUG) && defined(CONFIG_DEBUG)
+static bool sam_adc_checkreg(struct sam_gmac_s *priv, bool wr,
+                         uint32_t regval, uintptr_t address);
+static uint32_t sam_adc_getreg(struct sam_gmac_s *priv, uintptr_t addr);
+static void sam_adc_putreg(struct sam_gmac_s *priv, uintptr_t addr, uint32_t val);
+#else
+# define sam_adc_getreg(priv,addr)      getreg32(addr)
+# define sam_adc_putreg(priv,addr,val)  putreg32(val,addr)
+#endif
 
 /* ADC interrupt handling */
 
-static int  adc_interrupt(int irq, void *context);
+static int  sam_adc_interrupt(int irq, void *context);
 
 /* ADC methods */
 
-static void adc_reset(FAR struct adc_dev_s *dev);
-static int  adc_setup(FAR struct adc_dev_s *dev);
-static void adc_shutdown(FAR struct adc_dev_s *dev);
-static void adc_rxint(FAR struct adc_dev_s *dev, bool enable);
-static int  adc_ioctl(FAR struct adc_dev_s *dev, int cmd, unsigned long arg);
+static void sam_adc_reset(FAR struct adc_dev_s *dev);
+static int  sam_adc_setup(FAR struct adc_dev_s *dev);
+static void sam_adc_shutdown(FAR struct adc_dev_s *dev);
+static void sam_adc_rxint(FAR struct adc_dev_s *dev, bool enable);
+static int  sam_adc_ioctl(FAR struct adc_dev_s *dev, int cmd, unsigned long arg);
 
 /****************************************************************************
  * Private Data
@@ -100,11 +119,11 @@ static int  adc_ioctl(FAR struct adc_dev_s *dev, int cmd, unsigned long arg);
 
 static const struct adc_ops_s g_adcops =
 {
-  .ao_reset    = adc_reset,
-  .ao_setup    = adc_setup,
-  .ao_shutdown = adc_shutdown,
-  .ao_rxint    = adc_rxint,
-  .ao_ioctl    = adc_ioctl,
+  .ao_reset    = sam_adc_reset,
+  .ao_setup    = sam_adc_setup,
+  .ao_shutdown = sam_adc_shutdown,
+  .ao_rxint    = sam_adc_rxint,
+  .ao_ioctl    = sam_adc_ioctl,
 };
 
 /* ADC internal state */
@@ -126,15 +145,112 @@ static struct adc_dev_s g_adcdev =
  ****************************************************************************/
 
 /****************************************************************************
- * Name: adc_reset
+ * Name: sam_adc_checkreg
+ *
+ * Description:
+ *   Check if the current register access is a duplicate of the preceding.
+ *
+ * Input Parameters:
+ *   regval  - The value to be written
+ *   address - The address of the register to write to
+ *
+ * Returned Value:
+ *   true:  This is the first register access of this type.
+ *   flase: This is the same as the preceding register access.
+ *
+ ****************************************************************************/
+
+#ifdef CONFIG_SAMA5_ADC_REGDEBUG
+static bool sam_adc_checkreg(struct sam_gmac_s *priv, bool wr,
+                             uint32_t regval, uintptr_t address)
+{
+  if (wr      == priv->wrlast &&   /* Same kind of access? */
+      regval  == priv->vallast &&  /* Same value? */
+      address == priv->addrlast)   /* Same address? */
+    {
+      /* Yes, then just keep a count of the number of times we did this. */
+
+      priv->ntimes++;
+      return false;
+    }
+  else
+    {
+      /* Did we do the previous operation more than once? */
+
+      if (priv->ntimes > 0)
+        {
+          /* Yes... show how many times we did it */
+
+          lldbg("...[Repeats %d times]...\n", priv->ntimes);
+        }
+
+      /* Save information about the new access */
+
+      priv->wrlast   = wr;
+      priv->vallast  = regval;
+      priv->addrlast = address;
+      priv->ntimes   = 0;
+    }
+
+  /* Return true if this is the first time that we have done this operation */
+
+  return true;
+}
+#endif
+
+/****************************************************************************
+ * Name: sam_adc_getreg
+ *
+ * Description:
+ *  Read any 32-bit register using an absolute address.
+ *
+ ****************************************************************************/
+
+#ifdef CONFIG_SAMA5_ADC_REGDEBUG
+static uint32_t sam_adc_getreg(struct sam_gmac_s *priv, uintptr_t address)
+{
+  uint32_t regval = getreg32(address);
+
+  if (sam_adc_checkreg(priv, false, regval, address))
+    {
+      lldbg("%08x->%08x\n", address, regval);
+    }
+
+  return regval;
+}
+#endif
+
+/****************************************************************************
+ * Name: sam_adc_putreg
+ *
+ * Description:
+ *  Write to any 32-bit register using an absolute address.
+ *
+ ****************************************************************************/
+
+#ifdef CONFIG_SAMA5_ADC_REGDEBUG
+static void sam_adc_putreg(struct sam_gmac_s *priv, uintptr_t address,
+                       uint32_t regval)
+{
+  if (sam_adc_checkreg(priv, true, regval, address))
+    {
+      lldbg("%08x<-%08x\n", address, regval);
+    }
+
+  putreg32(regval, address);
+}
+#endif
+
+/****************************************************************************
+ * Name: sam_adc_reset
  *
  * Description:
  *   Reset the ADC device.  Called early to initialize the hardware. This
- *   is called, before adc_setup() and on error conditions.
+ *   is called, before sam_adc_setup() and on error conditions.
  *
  ****************************************************************************/
 
-static void adc_reset(FAR struct adc_dev_s *dev)
+static void sam_adc_reset(FAR struct adc_dev_s *dev)
 {
   FAR struct sam_adc_s *priv = (FAR struct sam_adc_s *)dev->ad_priv;
   irqstate_t flags;
@@ -147,7 +263,7 @@ static void adc_reset(FAR struct adc_dev_s *dev)
 }
 
 /****************************************************************************
- * Name: adc_setup
+ * Name: sam_adc_setup
  *
  * Description:
  *   Configure the ADC. This method is called the first time that the ADC
@@ -157,14 +273,14 @@ static void adc_reset(FAR struct adc_dev_s *dev)
  *
  ****************************************************************************/
 
-static int adc_setup(FAR struct adc_dev_s *dev)
+static int sam_adc_setup(FAR struct adc_dev_s *dev)
 {
   FAR struct sam_adc_s *priv = (FAR struct sam_adc_s *)dev->ad_priv;
   int ret;
 
   /* Attach the ADC interrupt */
 
-  ret = irq_attach(SAM_IRQ_ADC, adc_interrupt);
+  ret = irq_attach(SAM_IRQ_ADC, sam_adc_interrupt);
   if (ret < 0)
     {
       adbg("ERROR: Failed to attach IRQ %d: %d\n", SAM_IRQ_ADC, ret);
@@ -178,7 +294,7 @@ static int adc_setup(FAR struct adc_dev_s *dev)
 }
 
 /****************************************************************************
- * Name: adc_shutdown
+ * Name: sam_adc_shutdown
  *
  * Description:
  *   Disable the ADC.  This method is called when the ADC device is closed.
@@ -186,7 +302,7 @@ static int adc_setup(FAR struct adc_dev_s *dev)
  *
  ****************************************************************************/
 
-static void adc_shutdown(FAR struct adc_dev_s *dev)
+static void sam_adc_shutdown(FAR struct adc_dev_s *dev)
 {
   FAR struct sam_adc_s *priv = (FAR struct sam_adc_s *)dev->ad_priv;
 
@@ -203,14 +319,14 @@ static void adc_shutdown(FAR struct adc_dev_s *dev)
 }
 
 /****************************************************************************
- * Name: adc_rxint
+ * Name: sam_adc_rxint
  *
  * Description:
  *   Call to enable or disable RX interrupts
  *
  ****************************************************************************/
 
-static void adc_rxint(FAR struct adc_dev_s *dev, bool enable)
+static void sam_adc_rxint(FAR struct adc_dev_s *dev, bool enable)
 {
   FAR struct sam_adc_s *priv = (FAR struct sam_adc_s *)dev->ad_priv;
 
@@ -226,14 +342,14 @@ static void adc_rxint(FAR struct adc_dev_s *dev, bool enable)
 }
 
 /****************************************************************************
- * Name: adc_ioctl
+ * Name: sam_adc_ioctl
  *
  * Description:
  *  All ioctl calls will be routed through this method
  *
  ****************************************************************************/
 
-static int adc_ioctl(FAR struct adc_dev_s *dev, int cmd, unsigned long arg)
+static int sam_adc_ioctl(FAR struct adc_dev_s *dev, int cmd, unsigned long arg)
 {
   /* No ioctl commands supported */
 
@@ -241,14 +357,14 @@ static int adc_ioctl(FAR struct adc_dev_s *dev, int cmd, unsigned long arg)
 }
 
 /****************************************************************************
- * Name: adc_interrupt
+ * Name: sam_adc_interrupt
  *
  * Description:
  *   ADC interrupt handler
  *
  ****************************************************************************/
 
-static int adc_interrupt(int irq, void *context)
+static int sam_adc_interrupt(int irq, void *context)
 {
   FAR struct sam_adc_s *priv = (FAR struct sam_adc_s *)g_adcdev.ad_priv;
   uint32_t regval;
@@ -273,8 +389,22 @@ static int adc_interrupt(int irq, void *context)
  *
  ****************************************************************************/
 
-FAR struct adc_dev_s *sam_adcinitialize(void)
+FAR struct adc_dev_s *sam_adc_initialize(void)
 {
+  /* Enable the ADC peripheral clock*/
+
+  sam_adc_enableclk();
+
+  /* Reset the ADC controller */
+
+  sam_adc_putreg(priv, SAM_ADC_CR, ADC_CR_SWRST);
+
+  /* Reset Mode Register */
+
+  sam_adc_putreg(priv, SAM_ADC_MR, 0);
+
+  /* Return a pointer to the device structure */
+
   return &g_adcdev;
 }
 
diff --git a/nuttx/arch/arm/src/sama5/sam_adc.h b/nuttx/arch/arm/src/sama5/sam_adc.h
index 8a8f7ca51..8309c624c 100644
--- a/nuttx/arch/arm/src/sama5/sam_adc.h
+++ b/nuttx/arch/arm/src/sama5/sam_adc.h
@@ -1,7 +1,6 @@
 /****************************************************************************
  * arch/arm/src/sama5/sam_adc.h
  *
- *
  *   Copyright (C) 2013 Gregory Nutt. All rights reserved.
  *   Author: Gregory Nutt <gnutt@nuttx.org>
  *
@@ -44,6 +43,8 @@
 #include <nuttx/config.h>
 #include "chip/sam_adc.h"
 
+#ifdef CONFIG_SAMA5_ADC
+
 /****************************************************************************
  * Pre-processor Definitions
  ****************************************************************************/
@@ -81,13 +82,16 @@ extern "C"
  *
  ****************************************************************************/
 
-#ifdef CONFIG_LPC17_ADC
 FAR struct adc_dev_s *sam_adcinitialize(void);
-#endif
+
+/****************************************************************************
+ * Interfaces exported from the ADC to the touchscreen driver
+ ****************************************************************************/
 
 #undef EXTERN
 #ifdef __cplusplus
 }
 #endif
 
+#endif /* CONFIG_SAMA5_ADC */
 #endif /* __ARCH_ARM_SRC_SAMA5_SAM_ADC_H */
diff --git a/nuttx/arch/arm/src/sama5/sam_touchscreen.c b/nuttx/arch/arm/src/sama5/sam_touchscreen.c
new file mode 100644
index 000000000..3dcdac21f
--- /dev/null
+++ b/nuttx/arch/arm/src/sama5/sam_touchscreen.c
@@ -0,0 +1,965 @@
+/****************************************************************************
+ * arch/arm/src/sama5/sam_touchsreen.c
+ *
+ *   Copyright (C) 2013 Gregory Nutt. All rights reserved.
+ *   Authors: 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 <stdbool.h>
+#include <string.h>
+#include <semaphore.h>
+#include <poll.h>
+#include <wdog.h>
+#include <errno.h>
+#include <assert.h>
+#include <debug.h>
+
+#include <nuttx/arch.h>
+#include <nuttx/wqueue.h>
+
+#include <nuttx/input/touchscreen.h>
+
+#include "sam_touchscreen.h"
+
+#if defined(CONFIG_SAMA5_ADC) && defined(CONFIG_SAMA5_TOUCHSCREEN)
+
+/****************************************************************************
+ * Pre-processor Definitions
+ ****************************************************************************/
+/* Driver support ***********************************************************/
+/* This format is used to construct the /dev/input[n] device driver path.  It
+ * defined here so that it will be used consistently in all places.
+ */
+
+#define DEV_FORMAT      "/dev/input%d"
+#define DEV_NAMELEN     16
+
+/* Poll the pen position while the pen is down at this rate (50MS): */
+
+#define TSD_WDOG_DELAY  ((50 + (MSEC_PER_TICK-1))/ MSEC_PER_TICK)
+
+/* This is a value for the threshold that guantees a big difference on the
+ * first pendown (but can't overflow).
+ */
+
+#define INVALID_THRESHOLD 0x1000
+
+/****************************************************************************
+ * Private Types
+ ****************************************************************************/
+
+/* This describes the state of one contact */
+
+enum sam_contact_3
+{
+  CONTACT_NONE = 0,             /* No contact */
+  CONTACT_DOWN,                 /* First contact */
+  CONTACT_MOVE,                 /* Same contact, possibly different position */
+  CONTACT_UP,                   /* Contact lost */
+};
+
+/* This structure describes the results of one ADS7843E sample */
+
+struct sam_sample_s
+{
+  uint8_t id;                   /* Sampled touch point ID */
+  uint8_t contact;              /* Contact state (see enum sam_contact_e) */
+  bool valid;                   /* True: x,y contain valid, sampled data */
+  uint16_t x;                   /* Measured X position */
+  uint16_t y;                   /* Measured Y position */
+};
+
+/* This structure describes the state of one ADS7843E driver instance */
+
+struct sam_dev_s
+{
+  uint8_t nwaiters;             /* Number of threads waiting for ADS7843E data */
+  uint8_t id;                   /* Current touch point ID */
+  volatile bool penchange;      /* An unreported event is buffered */
+  uint16_t threshx;             /* Thresholding X value */
+  uint16_t threshy;             /* Thresholding Y value */
+  sem_t devsem;                 /* Manages exclusive access to this structure */
+  sem_t waitsem;                /* Used to wait for the availability of data */
+
+  struct work_s work;           /* Supports the interrupt handling "bottom half" */
+  struct sam_sample_s sample;   /* Last sampled touch point data */
+  WDOG_ID wdog;                 /* Poll the position while the pen is down */
+
+  /* The following is a list if poll structures of threads waiting for
+   * driver events. The 'struct pollfd' reference for each open is also
+   * retained in the f_priv field of the 'struct file'.
+   */
+
+#ifndef CONFIG_DISABLE_POLL
+  struct pollfd *fds[CONFIG_ADS7843E_NPOLLWAITERS];
+#endif
+};
+
+/****************************************************************************
+ * Private Function Prototypes
+ ****************************************************************************/
+
+/* Interrupt bottom half logic and data sampling */
+
+static void sam_notify(FAR struct sam_dev_s *priv);
+static int  sam_sample(FAR struct sam_dev_s *priv,
+              FAR struct sam_sample_s *sample);
+static int  sam_waitsample(FAR struct sam_dev_s *priv,
+              FAR struct sam_sample_s *sample);
+static void sam_bottomhalf(FAR void *arg);
+
+/* Character driver methods */
+
+static int  sam_open(FAR struct file *filep);
+static int  sam_close(FAR struct file *filep);
+static ssize_t sam_read(FAR struct file *filep, FAR char *buffer,
+              size_t len);
+static int  sam_ioctl(FAR struct file *filep, int cmd, unsigned long arg);
+#ifndef CONFIG_DISABLE_POLL
+static int  sam_poll(FAR struct file *filep, struct pollfd *fds, bool setup);
+#endif
+
+/****************************************************************************
+ * Private Data
+ ****************************************************************************/
+
+/* This the vtable that supports the character driver interface */
+
+static const struct file_operations g_tsdops =
+{
+  sam_open,    /* open */
+  sam_close,   /* close */
+  sam_read,    /* read */
+  0,           /* write */
+  0,           /* seek */
+  sam_ioctl    /* ioctl */
+#ifndef CONFIG_DISABLE_POLL
+  , sam_poll   /* poll */
+#endif
+};
+
+/* The driver state structure is pre-allocated. */
+
+static struct sam_dev_s g_tsd;
+
+/****************************************************************************
+ * Private Functions
+ ****************************************************************************/
+
+/****************************************************************************
+ * Name: sam_notify
+ ****************************************************************************/
+
+static void sam_notify(FAR struct sam_dev_s *priv)
+{
+#ifndef CONFIG_DISABLE_POLL
+  int i;
+#endif
+
+  /* If there are threads waiting for read data, then signal one of them
+   * that the read data is available.
+   */
+
+  if (priv->nwaiters > 0)
+    {
+      /* After posting this semaphore, we need to exit because the ADS7843E
+       * is no longer available.
+       */
+
+      sem_post(&priv->waitsem);
+    }
+
+  /* If there are threads waiting on poll() for ADS7843E data to become available,
+   * then wake them up now.  NOTE: we wake up all waiting threads because we
+   * do not know that they are going to do.  If they all try to read the data,
+   * then some make end up blocking after all.
+   */
+
+#ifndef CONFIG_DISABLE_POLL
+  for (i = 0; i < CONFIG_SAMA5_TSD_NPOLLWAITERS; i++)
+    {
+      struct pollfd *fds = priv->fds[i];
+      if (fds)
+        {
+          fds->revents |= POLLIN;
+          ivdbg("Report events: %02x\n", fds->revents);
+          sem_post(fds->sem);
+        }
+    }
+#endif
+}
+
+/****************************************************************************
+ * Name: sam_sample
+ ****************************************************************************/
+
+static int sam_sample(FAR struct sam_dev_s *priv,
+                      FAR struct sam_sample_s *sample)
+{
+  irqstate_t flags;
+  int ret = -EAGAIN;
+
+  /* Interrupts me be disabled when this is called to (1) prevent posting
+   * of semaphores from interrupt handlers, and (2) to prevent sampled data
+   * from changing until it has been reported.
+   */
+
+  flags = irqsave();
+
+  /* Is there new ADS7843E sample data available? */
+
+  if (priv->penchange)
+    {
+      /* Yes.. the state has changed in some way.  Return a copy of the
+       * sampled data.
+       */
+
+      memcpy(sample, &priv->sample, sizeof(struct sam_sample_s ));
+
+      /* Now manage state transitions */
+
+      if (sample->contact == CONTACT_UP)
+        {
+          /* Next.. no contact.  Increment the ID so that next contact ID
+           * will be unique.  X/Y positions are no longer valid.
+           */
+
+          priv->sample.contact = CONTACT_NONE;
+          priv->sample.valid   = false;
+          priv->id++;
+        }
+      else if (sample->contact == CONTACT_DOWN)
+       {
+          /* First report -- next report will be a movement */
+
+         priv->sample.contact = CONTACT_MOVE;
+       }
+
+      priv->penchange = false;
+      ret = OK;
+    }
+
+  irqrestore(flags);
+  return ret;
+}
+
+/****************************************************************************
+ * Name: sam_waitsample
+ ****************************************************************************/
+
+static int sam_waitsample(FAR struct sam_dev_s *priv,
+                               FAR struct sam_sample_s *sample)
+{
+  irqstate_t flags;
+  int ret;
+
+  /* Interrupts me be disabled when this is called to (1) prevent posting
+   * of semaphores from interrupt handlers, and (2) to prevent sampled data
+   * from changing until it has been reported.
+   *
+   * In addition, we will also disable pre-emption to prevent other threads
+   * from getting control while we muck with the semaphores.
+   */
+
+  sched_lock();
+  flags = irqsave();
+
+  /* Now release the semaphore that manages mutually exclusive access to
+   * the device structure.  This may cause other tasks to become ready to
+   * run, but they cannot run yet because pre-emption is disabled.
+   */
+
+  sem_post(&priv->devsem);
+
+  /* Try to get the a sample... if we cannot, then wait on the semaphore
+   * that is posted when new sample data is available.
+   */
+
+  while (sam_sample(priv, sample) < 0)
+    {
+      /* Wait for a sample data */
+
+      ivdbg("Waiting..\n");
+      priv->nwaiters++;
+      ret = sem_wait(&priv->waitsem);
+      priv->nwaiters--;
+
+      if (ret < 0)
+        {
+          /* If we are awakened by a signal, then we need to return
+           * the failure now.
+           */
+
+          idbg("sem_wait: %d\n", errno);
+          DEBUGASSERT(errno == EINTR);
+          ret = -EINTR;
+          goto errout;
+        }
+    }
+
+  ivdbg("Sampled\n");
+
+   /* Re-acquire the semaphore that manages mutually exclusive access to
+   * the device structure.  We may have to wait here.  But we have our sample.
+   * Interrupts and pre-emption will be re-enabled while we wait.
+   */
+
+  ret = sem_wait(&priv->devsem);
+
+errout:
+  /* Then re-enable interrupts.  We might get interrupt here and there
+   * could be a new sample.  But no new threads will run because we still
+   * have pre-emption disabled.
+   */
+
+  irqrestore(flags);
+
+  /* Restore pre-emption.  We might get suspended here but that is okay
+   * because we already have our sample.  Note:  this means that if there
+   * were two threads reading from the touchscreen ADC for some reason, the
+   * data might be read out of order.
+   */
+
+  sched_unlock();
+  return ret;
+}
+
+/****************************************************************************
+ * Name: sam_schedule
+ ****************************************************************************/
+
+static int sam_schedule(FAR struct sam_dev_s *priv)
+{
+  int ret;
+
+  /* Disable further interrupts.  touchscreen ADC interrupts will be re-enabled
+   * after the worker thread executes.
+   */
+#warning "Missing logic"
+
+  /* Disable the watchdog timer.  It will be re-enabled in the worker thread
+   * while the pen remains down.
+   */
+
+  wd_cancel(priv->wdog);
+
+  /* Transfer processing to the worker thread.  Since touchscreen ADC interrupts are
+   * disabled while the work is pending, no special action should be required
+   * to protected the work queue.
+   */
+
+  DEBUGASSERT(priv->work.worker == NULL);
+  ret = work_queue(HPWORK, &priv->work, sam_bottomhalf, priv, 0);
+  if (ret != 0)
+    {
+      illdbg("Failed to queue work: %d\n", ret);
+    }
+
+  return OK;
+}
+
+/****************************************************************************
+ * Name: sam_wdog
+ ****************************************************************************/
+
+static void sam_wdog(int argc, uint32_t arg1, ...)
+{
+  FAR struct sam_dev_s *priv = (FAR struct sam_dev_s *)((uintptr_t)arg1);
+  (void)sam_schedule(priv);
+}
+
+/****************************************************************************
+ * Name: sam_bottomhalf
+ ****************************************************************************/
+
+static void sam_bottomhalf(FAR void *arg)
+{
+  FAR struct sam_dev_s *priv = (FAR struct sam_dev_s *)arg;
+  uint16_t x;
+  uint16_t y;
+  uint16_t xdiff;
+  uint16_t ydiff;
+  bool pendown;
+  int ret;
+
+  ASSERT(priv != NULL);
+
+  /* Disable the watchdog timer.  This is safe because it is started only
+   * by this function and this function is serialized on the worker thread.
+   */
+
+  wd_cancel(priv->wdog);
+
+  /* Get exclusive access to the driver data structure */
+
+  do
+    {
+      ret = sem_wait(&priv->devsem);
+
+      /* This should only fail if the wait was canceled by an signal
+       * (and the worker thread will receive a lot of signals).
+       */
+
+      DEBUGASSERT(ret == OK || errno == EINTR);
+    }
+  while (ret < 0);
+
+  /* Check for pen up or down by reading the PENIRQ GPIO. */
+#warning Missing logic
+
+  /* Handle the change from pen down to pen up */
+
+  if (!pendown)
+    {
+      /* The pen is up.. reset thresholding variables. */
+
+      priv->threshx = INVALID_THRESHOLD;
+      priv->threshy = INVALID_THRESHOLD;
+
+      /* Ignore the interrupt if the pen was already up (CONTACT_NONE == pen up
+       * and already reported; CONTACT_UP == pen up, but not reported)
+       */
+
+      if (priv->sample.contact == CONTACT_NONE ||
+          priv->sample.contact == CONTACT_UP)
+
+        {
+          goto ignored;
+        }
+
+      /* The pen is up.  NOTE: We know from a previous test, that this is a
+       * loss of contact condition.  This will be changed to CONTACT_NONE
+       * after the loss of contact is sampled.
+       */
+
+       priv->sample.contact = CONTACT_UP;
+    }
+
+  /* It is a pen down event.  If the last loss-of-contact event has not been
+   * processed yet, then we have to ignore the pen down event (or else it will
+   * look like a drag event)
+   */
+
+  else if (priv->sample.contact == CONTACT_UP)
+    {
+      /* If we have not yet processed the last pen up event, then we
+       * cannot handle this pen down event. We will have to discard it.  That
+       * should be okay because we will set the timer to to sample again
+       * later.
+       */
+
+       wd_start(priv->wdog, TSD_WDOG_DELAY, sam_wdog, 1, (uint32_t)priv);
+       goto ignored;
+    }
+  else
+    {
+      /* Handle pen down events.  First, sample positional values. */
+#warning Missing logic
+
+      /* Perform a thresholding operation so that the results will be more stable.
+       * If the difference from the last sample is small, then ignore the event.
+       * REVISIT:  Should a large change in pressure also generate a event?
+       */
+
+      xdiff = x > priv->threshx ? (x - priv->threshx) : (priv->threshx - x);
+      ydiff = y > priv->threshy ? (y - priv->threshy) : (priv->threshy - y);
+
+      /* Continue to sample the position while the pen is down */
+
+      wd_start(priv->wdog, TSD_WDOG_DELAY, sam_wdog, 1, (uint32_t)priv);
+
+      /* Check the thresholds.  Bail if there is no significant difference */
+
+      if (xdiff < CONFIG_SAMA5_TSD_THRESHX && ydiff < CONFIG_SAMA5_TSD_THRESHY)
+        {
+          /* Little or no change in either direction ... don't report anything. */
+
+          goto ignored;
+        }
+
+      /* When we see a big difference, snap to the new x/y thresholds */
+
+      priv->threshx       = x;
+      priv->threshy       = y;
+
+      /* Update the x/y position in the sample data */
+
+      priv->sample.x      = priv->threshx;
+      priv->sample.y      = priv->threshy;
+
+      /* The X/Y positional data is now valid */
+
+      priv->sample.valid = true;
+
+      /* If this is the first (acknowledged) pen down report, then report
+       * this as the first contact.  If contact == CONTACT_DOWN, it will be
+       * set to set to CONTACT_MOVE after the contact is first sampled.
+       */
+
+      if (priv->sample.contact != CONTACT_MOVE)
+        {
+          /* First contact */
+
+          priv->sample.contact = CONTACT_DOWN;
+        }
+    }
+
+  /* Indicate the availability of new sample data for this ID */
+
+  priv->sample.id = priv->id;
+  priv->penchange = true;
+
+  /* Notify any waiters that new ADS7843E data is available */
+
+  sam_notify(priv);
+
+  /* Exit, re-enabling ADS7843E interrupts */
+
+ignored:
+
+  /* Re-enable the PENIRQ interrupts */
+#warning Missing logic
+
+  /* Re-enable the PENIRQ interrupt at the MCU's interrupt controller */
+#warning Missing logic
+
+  /* Release our lock on the state structure */
+
+  sem_post(&priv->devsem);
+}
+
+/****************************************************************************
+ * Name: sam_open
+ ****************************************************************************/
+
+static int sam_open(FAR struct file *filep)
+{
+  ivdbg("Opening\n");
+  return OK;
+}
+
+/****************************************************************************
+ * Name: sam_close
+ ****************************************************************************/
+
+static int sam_close(FAR struct file *filep)
+{
+  ivdbg("Closing\n");
+  return OK;
+}
+
+/****************************************************************************
+ * Name: sam_read
+ ****************************************************************************/
+
+static ssize_t sam_read(FAR struct file *filep, FAR char *buffer, size_t len)
+{
+  FAR struct inode *inode;
+  FAR struct sam_dev_s *priv;
+  FAR struct touch_sample_s *report;
+  struct sam_sample_s sample;
+  int ret;
+
+  ivdbg("buffer:%p len:%d\n", buffer, len);
+  DEBUGASSERT(filep);
+  inode = filep->f_inode;
+
+  DEBUGASSERT(inode && inode->i_private);
+  priv  = (FAR struct sam_dev_s *)inode->i_private;
+
+  /* Verify that the caller has provided a buffer large enough to receive
+   * the touch data.
+   */
+
+  if (len < SIZEOF_TOUCH_SAMPLE_S(1))
+    {
+      /* We could provide logic to break up a touch report into segments and
+       * handle smaller reads... but why?
+       */
+
+      idbg("Unsupported read size: %d\n", len);
+      return -ENOSYS;
+    }
+
+  /* Get exclusive access to the driver data structure */
+
+  ret = sem_wait(&priv->devsem);
+  if (ret < 0)
+    {
+      /* This should only happen if the wait was canceled by an signal */
+
+      idbg("sem_wait: %d\n", errno);
+      DEBUGASSERT(errno == EINTR);
+      return -EINTR;
+    }
+
+  /* Try to read sample data. */
+
+  ret = sam_sample(priv, &sample);
+  if (ret < 0)
+    {
+      /* Sample data is not available now.  We would ave to wait to get
+       * receive sample data.  If the user has specified the O_NONBLOCK
+       * option, then just return an error.
+       */
+
+      ivdbg("Sample data is not available\n");
+      if (filep->f_oflags & O_NONBLOCK)
+        {
+          ret = -EAGAIN;
+          goto errout;
+       }
+
+      /* Wait for sample data */
+
+      ret = sam_waitsample(priv, &sample);
+      if (ret < 0)
+        {
+          /* We might have been awakened by a signal */
+
+          idbg("sam_waitsample: %d\n", ret);
+          goto errout;
+        }
+    }
+
+  /* In any event, we now have sampled ADS7843E data that we can report
+   * to the caller.
+   */
+
+  report = (FAR struct touch_sample_s *)buffer;
+  memset(report, 0, SIZEOF_TOUCH_SAMPLE_S(1));
+  report->npoints            = 1;
+  report->point[0].id        = sample.id;
+  report->point[0].x         = sample.x;
+  report->point[0].y         = sample.y;
+
+  /* Report the appropriate flags */
+
+  if (sample.contact == CONTACT_UP)
+    {
+       /* Pen is now up.  Is the positional data valid?  This is important to
+        * know because the release will be sent to the window based on its
+        * last positional data.
+        */
+
+      if (sample.valid)
+        {
+          report->point[0].flags  = TOUCH_UP | TOUCH_ID_VALID | TOUCH_POS_VALID;
+        }
+      else
+        {
+          report->point[0].flags  = TOUCH_UP | TOUCH_ID_VALID;
+        }
+    }
+  else if (sample.contact == CONTACT_DOWN)
+    {
+      /* First contact */
+
+      report->point[0].flags  = TOUCH_DOWN | TOUCH_ID_VALID | TOUCH_POS_VALID;
+    }
+  else /* if (sample->contact == CONTACT_MOVE) */
+    {
+      /* Movement of the same contact */
+
+      report->point[0].flags  = TOUCH_MOVE | TOUCH_ID_VALID | TOUCH_POS_VALID;
+    }
+
+  ivdbg("  id:      %d\n", report->point[0].id);
+  ivdbg("  flags:   %02x\n", report->point[0].flags);
+  ivdbg("  x:       %d\n", report->point[0].x);
+  ivdbg("  y:       %d\n", report->point[0].y);
+
+  ret = SIZEOF_TOUCH_SAMPLE_S(1);
+
+errout:
+  sem_post(&priv->devsem);
+  ivdbg("Returning: %d\n", ret);
+  return ret;
+}
+
+/****************************************************************************
+ * Name:sam_ioctl
+ ****************************************************************************/
+
+static int sam_ioctl(FAR struct file *filep, int cmd, unsigned long arg)
+{
+  FAR struct inode         *inode;
+  FAR struct sam_dev_s *priv;
+  int                       ret;
+
+  ivdbg("cmd: %d arg: %ld\n", cmd, arg);
+  DEBUGASSERT(filep);
+  inode = filep->f_inode;
+
+  DEBUGASSERT(inode && inode->i_private);
+  priv  = (FAR struct sam_dev_s *)inode->i_private;
+
+  /* Get exclusive access to the driver data structure */
+
+  ret = sem_wait(&priv->devsem);
+  if (ret < 0)
+    {
+      /* This should only happen if the wait was canceled by an signal */
+
+      DEBUGASSERT(errno == EINTR);
+      return -EINTR;
+    }
+
+  /* Process the IOCTL by command */
+
+  switch (cmd)
+    {
+      default:
+        ret = -ENOTTY;
+        break;
+    }
+
+  sem_post(&priv->devsem);
+  return ret;
+}
+
+/****************************************************************************
+ * Name: sam_poll
+ ****************************************************************************/
+
+#ifndef CONFIG_DISABLE_POLL
+static int sam_poll(FAR struct file *filep, FAR struct pollfd *fds,
+                        bool setup)
+{
+  FAR struct inode         *inode;
+  FAR struct sam_dev_s *priv;
+  int                       ret = OK;
+  int                       i;
+
+  ivdbg("setup: %d\n", (int)setup);
+  DEBUGASSERT(filep && fds);
+  inode = filep->f_inode;
+
+  DEBUGASSERT(inode && inode->i_private);
+  priv  = (FAR struct sam_dev_s *)inode->i_private;
+
+  /* Are we setting up the poll?  Or tearing it down? */
+
+  ret = sem_wait(&priv->devsem);
+  if (ret < 0)
+    {
+      /* This should only happen if the wait was canceled by an signal */
+
+      DEBUGASSERT(errno == EINTR);
+      return -EINTR;
+    }
+
+  if (setup)
+    {
+      /* Ignore waits that do not include POLLIN */
+
+      if ((fds->events & POLLIN) == 0)
+        {
+          ret = -EDEADLK;
+          goto errout;
+        }
+
+      /* This is a request to set up the poll.  Find an available
+       * slot for the poll structure reference
+       */
+
+      for (i = 0; i < CONFIG_SAMA5_TSD_NPOLLWAITERS; i++)
+        {
+          /* Find an available slot */
+
+          if (!priv->fds[i])
+            {
+              /* Bind the poll structure and this slot */
+
+              priv->fds[i] = fds;
+              fds->priv    = &priv->fds[i];
+              break;
+            }
+        }
+
+      if (i >= CONFIG_SAMA5_TSD_NPOLLWAITERS)
+        {
+          fds->priv    = NULL;
+          ret          = -EBUSY;
+          goto errout;
+        }
+
+      /* Should we immediately notify on any of the requested events? */
+
+      if (priv->penchange)
+        {
+          sam_notify(priv);
+        }
+    }
+  else if (fds->priv)
+    {
+      /* This is a request to tear down the poll. */
+
+      struct pollfd **slot = (struct pollfd **)fds->priv;
+      DEBUGASSERT(slot != NULL);
+
+      /* Remove all memory of the poll setup */
+
+      *slot                = NULL;
+      fds->priv            = NULL;
+    }
+
+errout:
+  sem_post(&priv->devsem);
+  return ret;
+}
+#endif
+
+/****************************************************************************
+ * Public Functions
+ ****************************************************************************/
+
+/****************************************************************************
+ * Public Functions
+ ****************************************************************************/
+
+/****************************************************************************
+ * Name: sam_tsd_register
+ *
+ * Description:
+ *   Configure the SAMA5 touchscreen.  This will register the driver as
+ *   /dev/inputN where N is the minor device number
+ *
+ * Input Parameters:
+ *   minor   - The input device minor number
+ *
+ * Returned Value:
+ *   Zero is returned on success.  Otherwise, a negated errno value is
+ *   returned to indicate the nature of the failure.
+ *
+ ****************************************************************************/
+
+int sam_tsd_register(int minor)
+{
+  FAR struct sam_dev_s *priv = &g_tsd;
+  char devname[DEV_NAMELEN];
+  int ret;
+
+  ivdbg("minor: %d\n", minor);
+
+  /* Debug-only sanity checks */
+
+  DEBUGASSERT(minor >= 0 && minor < 100);
+
+  /* Initialize the touchscreen device driver instance */
+
+  memset(priv, 0, sizeof(struct sam_dev_s));
+  priv->wdog    = wd_create();       /* Create a watchdog timer */
+  priv->threshx = INVALID_THRESHOLD; /* Initialize thresholding logic */
+  priv->threshy = INVALID_THRESHOLD; /* Initialize thresholding logic */
+
+  sem_init(&priv->devsem,  0, 1);    /* Initialize device structure semaphore */
+  sem_init(&priv->waitsem, 0, 0);    /* Initialize pen event wait semaphore */
+
+  /* Make sure that interrupts are disabled and clear any pending interrupts */
+#warning Missing logic
+
+  /* Attach the interrupt handler */
+#warning Missing logic
+
+  /* Enable the PEN IRQ */
+#warning Missing logic
+
+  /* Register the device as an input device */
+
+  (void)snprintf(devname, DEV_NAMELEN, DEV_FORMAT, minor);
+  ivdbg("Registering %s\n", devname);
+
+  ret = register_driver(devname, &g_tsdops, 0666, priv);
+  if (ret < 0)
+    {
+      idbg("register_driver() failed: %d\n", ret);
+      goto errout_with_priv;
+    }
+
+  /* Schedule work to perform the initial sampling and to set the data
+   * availability conditions.
+   */
+
+  ret = work_queue(HPWORK, &priv->work, sam_bottomhalf, priv, 0);
+  if (ret != 0)
+    {
+      idbg("Failed to queue work: %d\n", ret);
+      goto errout_with_priv;
+    }
+
+  /* And return success */
+
+  return OK;
+
+errout_with_priv:
+  sem_destroy(&priv->devsem);
+  sem_destroy(&priv->waitsem);
+  return ret;
+}
+
+/****************************************************************************
+ * Name: sam_tsd_interrupt
+ *
+ * Description:
+ *   Handles ADC interrupts associated with touchscreen channels
+ *
+ * Input parmeters:
+ *   None
+ *
+ * Returned Value:
+ *   None
+ * 
+ ****************************************************************************/
+
+void sam_tsd_interrupt(void)
+{
+  FAR struct sam_dev_s *priv = &g_tsd;
+  int ret;
+
+  /* Schedule sampling to occur on the worker thread */
+
+  ret = sam_schedule(priv);
+
+  /* Clear any pending interrupts and return success */
+#warning Missing logic
+  return ret;
+}
+
+#endif /* CONFIG_SAMA5_ADC && CONFIG_SAMA5_TOUCHSCREEN */
diff --git a/nuttx/arch/arm/src/sama5/sam_touchscreen.h b/nuttx/arch/arm/src/sama5/sam_touchscreen.h
new file mode 100644
index 000000000..8a68f2206
--- /dev/null
+++ b/nuttx/arch/arm/src/sama5/sam_touchscreen.h
@@ -0,0 +1,117 @@
+/****************************************************************************
+ * arch/arm/src/sama5/sam_adc.h
+ *
+ *   Copyright (C) 2013 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.
+ *
+ ****************************************************************************/
+
+#ifndef __ARCH_ARM_SRC_SAMA5_SAM_ADC_H
+#define __ARCH_ARM_SRC_SAMA5_SAM_ADC_H
+
+/****************************************************************************
+ * Included Files
+ ****************************************************************************/
+
+#include <nuttx/config.h>
+#include "chip/sam_adc.h"
+
+#if defined(CONFIG_SAMA5_ADC) && defined(CONFIG_SAMA5_TOUCHSCREEN)
+
+/****************************************************************************
+ * Pre-processor Definitions
+ ****************************************************************************/
+/* Configuration ************************************************************/
+
+/****************************************************************************
+ * Public Types
+ ****************************************************************************/
+
+/****************************************************************************
+ * Public Data
+ ****************************************************************************/
+
+#undef EXTERN
+#if defined(__cplusplus)
+#define EXTERN extern "C"
+extern "C"
+{
+#else
+#define EXTERN extern
+#endif
+
+/****************************************************************************
+ * Public Functions
+ ****************************************************************************/
+
+/****************************************************************************
+ * Name: sam_tsd_register
+ *
+ * Description:
+ *   Configure the SAMA5 touchscreen.  This will register the driver as
+ *   /dev/inputN where N is the minor device number
+ *
+ * Input Parameters:
+ *   minor   - The input device minor number
+ *
+ * Returned Value:
+ *   Zero is returned on success.  Otherwise, a negated errno value is
+ *   returned to indicate the nature of the failure.
+ *
+ ****************************************************************************/
+
+int sam_tsd_register(int minor);
+
+/****************************************************************************
+ * Interfaces exported from the touchscreen to the ADC driver
+ ****************************************************************************/
+/****************************************************************************
+ * Name: sam_tsd_interrupt
+ *
+ * Description:
+ *   Handles ADC interrupts associated with touchscreen channels
+ *
+ * Input parmeters:
+ *   None
+ *
+ * Returned Value:
+ *   None
+ * 
+ ****************************************************************************/
+
+void sam_tsd_interrupt(void);
+
+#undef EXTERN
+#ifdef __cplusplus
+}
+#endif
+
+#endif /* CONFIG_SAMA5_ADC && CONFIG_SAMA5_TOUCHSCREEN */
+#endif /* __ARCH_ARM_SRC_SAMA5_SAM_ADC_H */