Add support for an automounter that will automatically mount and unmount a file system a media is inserted and removed

4 files changed, 828 insertions, 0 deletions

diff --git a/nuttx/fs/Kconfig b/nuttx/fs/Kconfig
index b175276fa..12a68e36b 100644
--- a/nuttx/fs/Kconfig
+++ b/nuttx/fs/Kconfig
@@ -9,6 +9,26 @@ config DISABLE_MOUNTPOINT
 	bool "Disable support for mount points"
 	default n
 
+config FS_AUTOMOUNTER
+	bool "Auto-mounter"
+	default n
+	depends on !DISABLE_MOUNTPOINT
+	---help---
+		The automounter provides an OS-internal mechanism for automatically
+		mounting and unmounting removable media as the media is inserted and
+		removed.  See include/nuttx/fs/automout.h for interfacing details.
+
+config FS_AUTOMOUNTER_DEBUG
+	bool "Auto-mounter debug"
+	default n
+	depends on FS_AUTOMOUNTER && DEBUG
+	---help---
+		Normally, the auto-mounter will generate debug output when sub-system
+		level file system debug is enabled.  This option will select debug
+		output from the logic related to the auto-mount feature even when file
+		system debug is not enable.  This is useful primarily for in vivo
+		unit testing of the auto-mount feature.
+
 config DISABLE_PSEUDOFS_OPERATIONS
 	bool "Disable pseudo-filesystem operations"
 	default y if DEFAULT_SMALL
diff --git a/nuttx/fs/Makefile b/nuttx/fs/Makefile
index 3acfe606d..ebe1ee32b 100644
--- a/nuttx/fs/Makefile
+++ b/nuttx/fs/Makefile
@@ -106,6 +106,10 @@ ifneq ($(CONFIG_DISABLE_MOUNTPOINT),y)
 
 CSRCS += fs_fsync.c fs_mount.c fs_umount.c fs_foreachmountpoint.c
 
+ifeq ($(CONFIG_FS_AUTOMOUNTER),y)
+CSRCS += fs_automount.c
+endif
+
 include fat/Make.defs
 include romfs/Make.defs
 include nxffs/Make.defs
diff --git a/nuttx/fs/fs_automount.c b/nuttx/fs/fs_automount.c
new file mode 100644
index 000000000..965140a1c
--- /dev/null
+++ b/nuttx/fs/fs_automount.c
@@ -0,0 +1,613 @@
+/****************************************************************************
+ * fs/fs_automount.c
+ *
+ *   Copyright (C) 2014 Gregory Nutt. All rights reserved.
+ *   Author: Gregory Nutt <gnutt@nuttx.org>
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ *
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in
+ *    the documentation and/or other materials provided with the
+ *    distribution.
+ * 3. Neither the name NuttX nor the names of its contributors may be
+ *    used to endorse or promote products derived from this software
+ *    without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
+ * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
+ * COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
+ * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
+ * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
+ * OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
+ * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
+ * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
+ * ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
+ * POSSIBILITY OF SUCH DAMAGE.
+ *
+ ****************************************************************************/
+
+/****************************************************************************
+ * Included Files
+ ****************************************************************************/
+
+#include <nuttx/config.h>
+
+#if defined(CONFIG_FS_AUTOMOUNTER_DEBUG) && !defined(CONFIG_DEBUG_FS)
+#  define CONFIG_DEBUG_FS 1
+#endif
+
+#include <sys/mount.h>
+
+#include <stdbool.h>
+#include <wdog.h>
+#include <errno.h>
+#include <assert.h>
+#include <debug.h>
+
+#include <nuttx/kmalloc.h>
+#include <nuttx/wqueue.h>
+#include <nuttx/fs/automount.h>
+
+#include "fs_internal.h"
+
+/****************************************************************************
+ * Pre-processor Definitions
+ ****************************************************************************/
+/* Configuration ************************************************************
+ *
+ * CONFIG_FS_AUTOMOUNTER - Enables AUTOMOUNT support
+ */
+
+/* Pre-requisites */
+
+#ifndef CONFIG_SCHED_WORKQUEUE
+#  error Work queue support is required (CONFIG_SCHED_WORKQUEUE)
+#endif
+
+/* Return Values */
+
+#define OK_EXIST   0
+#define OK_NOENT   1
+
+/****************************************************************************
+ * Private Types
+ ****************************************************************************/
+/* This structure describes the state of the automounter */
+
+struct automounter_state_s
+{
+  FAR const struct automount_lower_s *lower; /* Board level interfaces */
+  struct work_s work;                        /* Work queue support */
+  WDOG_ID wdog;                              /* Delay to retry un-mounts */
+  bool mounted;                              /* True: Volume has been mounted */
+  bool inserted;                             /* True: Media has been inserted */
+};
+
+/****************************************************************************
+ * Private Function Prototypes
+ ****************************************************************************/
+
+static int  automount_findinode(FAR const char *path);
+static void automount_mount(FAR struct automounter_state_s *priv);
+static int  automount_unmount(FAR struct automounter_state_s *priv);
+static void automount_timeout(int argc, uint32_t arg1, ...);
+static void automount_worker(FAR void *arg);
+static int  automount_interrupt(FAR const struct automount_lower_s *lower,
+              FAR void *arg, bool inserted);
+
+/****************************************************************************
+ * Private Data
+ ****************************************************************************/
+
+/****************************************************************************
+ * Public Data
+ ****************************************************************************/
+
+/****************************************************************************
+ * Private Functions
+ ****************************************************************************/
+
+/****************************************************************************
+ * Name: automount_findinode
+ *
+ * Description:
+ *   Find the mountpoint inode in the inode tree.
+ *
+ * Input Parameters:
+ *   mntpath - Mountpoint path
+ *
+ * Returned Value:
+ *   OK_EXIST if the inode exists
+ *   OK_NOENT if the indoe does not exist
+ *   Negated errno if some failure occurs
+ *
+ ****************************************************************************/
+
+static int automount_findinode(FAR const char *path)
+{
+  FAR struct inode *node;
+  FAR const char *srchpath;
+  FAR const char *relpath;
+  int ret;
+
+  /* Make sure that we were given an absolute path */
+
+  DEBUGASSERT(path && path[0] == '/');
+
+  /* Get exclusive access to the in-memory inode tree. */
+
+  inode_semtake();
+
+  /* Find the inode */
+
+  srchpath = path;
+  node = inode_search(&srchpath, (FAR struct inode**)NULL,
+                      (FAR struct inode**)NULL, &relpath);
+  /* Did we find it? */
+
+  if (!node)
+    {
+      /* No.. Not found */
+
+      ret = OK_NOENT;
+    }
+
+  /* Yes.. is it a mount point? */
+
+  else if (INODE_IS_MOUNTPT(node))
+    {
+      /* Yes.. we found a mountpoint at this path */
+
+      ret = OK_EXIST;
+    }
+  else
+    {
+      /* No.. then somethin is in the way */
+
+      ret = -ENOTDIR;
+    }
+
+  /* Relinquish our exclusive access to the inode try and return the result */
+
+  inode_semgive();
+  return ret;
+}
+
+/****************************************************************************
+ * Name: automount_mount
+ *
+ * Description:
+ *   Media has been inserted, mount the volume.
+ *
+ * Input Parameters:
+ *   priv - A reference to out private state structure
+ *
+ * Returned Value:
+ *   None
+ *
+ ****************************************************************************/
+
+static void automount_mount(FAR struct automounter_state_s *priv)
+{
+  FAR const struct automount_lower_s *lower = priv->lower;
+  int ret;
+
+  /* Check if the something is already mounted at the mountpoint. */
+
+  ret = automount_findinode(lower->mountpoint);
+  switch (ret)
+    {
+    case OK_EXIST:
+      /* REVISIT: What should we do in this case?  I think that this would
+       * happen only if a previous unmount failed?  I suppose that we should
+       * try to unmount again because the mount might be stale.
+       */
+
+      fdbg("WARNING: Mountpoint %s already exists\n", lower->mountpoint);
+      ret = automount_unmount(priv);
+      if (ret < 0)
+        {
+          /* We failed to unmount (again?).  Complain and abort. */
+
+          fdbg("ERROR: automount_unmount failed: %d\n", ret);
+          return;
+        }
+
+      /* We successfully unmounted the file system.  Fall through to
+       * mount it again.
+       */
+
+    case OK_NOENT:
+      /* If we get here, then the volume must not be mounted */
+
+      DEBUGASSERT(!priv->mounted);
+
+       /* Mount the file system */
+
+      ret = mount(lower->blockdev, lower->mountpoint, lower->fstype,
+                  0, NULL);
+      if (ret < 0)
+        {
+          int errcode = get_errno();
+          DEBUGASSERT(errcode > 0);
+
+          fdbg("ERROR: Mount failed: %d\n", errcode);
+          UNUSED(errcode);
+          return;
+        }
+
+      /* Indicate that the volume is mounted */
+
+      priv->mounted = true;
+      break;
+      
+    default:
+      fdbg("ERROR: automount_findinode failed: %d\n", ret);
+      break;
+    }
+}
+
+/****************************************************************************
+ * Name: automount_unmount
+ *
+ * Description:
+ *   Media has been removed, unmount the volume.
+ *
+ * Input Parameters:
+ *   priv - A reference to out private state structure
+ *
+ * Returned Value:
+ *   OK if the volume was successfully mounted.  A negated errno value
+ *   otherwise.
+ *
+ ****************************************************************************/
+
+static int automount_unmount(FAR struct automounter_state_s *priv)
+{
+  FAR const struct automount_lower_s *lower = priv->lower;
+  int ret;
+
+  /* Check if the something is already mounted at the mountpoint. */
+
+  ret = automount_findinode(lower->mountpoint);
+  switch (ret)
+    {
+    case OK_EXIST:
+      /* If we get here, then the volume must be mounted */
+
+      DEBUGASSERT(priv->mounted);
+
+      /* Un-mount the volume */
+
+      ret = umount(lower->mountpoint);
+      if (ret < 0)
+        {
+          int errcode = get_errno();
+          DEBUGASSERT(errcode > 0);
+
+          /* We expect the error to be EBUSY meaning that the volume could
+           * not be unmounted because there are currently reference via open
+           * files or directories.
+           */
+
+          if (errcode == EBUSY)
+            {
+              fvdbg("WARNING: Volume is busy, try again later\n");
+
+              /* Start a timer to retry the umount after a delay */
+
+              ret = wd_start(priv->wdog, lower->udelay, automount_timeout, 1,
+                             (uint32_t)((uintptr_t)priv));
+              if (ret < 0)
+                {
+                  errcode = get_errno();
+                  DEBUGASSERT(errcode > 0);
+
+                  fdbg("ERROR: wd_start failed: %d\n", errcode);
+                  return -ret;
+                }
+            }
+
+          /* Other errors are fatal */
+
+          else
+            {
+              fvdbg("ERROR: umount failed: %d\n", errcode);
+              return -errcode;
+            }
+        }
+
+      /* Successfully unmounted */
+
+      priv->mounted = false;
+      return OK;
+
+    case OK_NOENT:
+      /* I suppose this is okay */
+
+      return OK;
+
+    default:
+      fdbg("ERROR: automount_findinode failed: %d\n", ret);
+      return ret;
+    }
+}
+
+/****************************************************************************
+ * Name: automount_timeout
+ *
+ * Description:
+ *   A previous unmount failed because the volume was busy... busy meaning
+ *   the volume could not be unmounted because there are open references
+ *   the files or directories in the volume.  When this failure occurred,
+ *   the unmount logic setup a delay and this function is called as a result
+ *   of that delay timeout.
+ *
+ *   This function will attempt the unmount again.
+ *
+ * Input Parameters:
+ *   Standard wdog timeout parameters
+ *
+ * Returned Value:
+ *   None
+ *
+ ****************************************************************************/
+
+static void automount_timeout(int argc, uint32_t arg1, ...)
+{
+  FAR struct automounter_state_s *priv =
+    (FAR struct automounter_state_s *)((uintptr_t)arg1);
+  int ret;
+
+  DEBUGASSERT(argc == 1 && priv);
+
+  /* Check the state of things.  This timeout at the interrupt level and
+   * will cancel the timeout if there is any change in the insertion
+   * state.  So we should still have the saved state as NOT inserted and
+   * there should be no pending work.
+   */
+
+  fllvdbg("inserted=%d\n", priv->inserted);
+  DEBUGASSERT(!priv->inserted && work_available(&priv->work));
+
+  /* Queue work to occur immediately. */
+
+  ret = work_queue(LPWORK, &priv->work, automount_worker, priv,  0);
+  if (ret < 0)
+    {
+      /* NOTE: Currently, work_cancel only returns success */
+
+      fdbg("ERROR: Failed to schedule work: %d\n", ret);
+    }
+}
+
+/****************************************************************************
+ * Name: automount_worker
+ *
+ * Description:
+ *   Performs automount actions on the worker thread.
+ *
+ * Input Parameters:
+ *   arg - Work argument set by work_queue()
+ *
+ * Returned Value:
+ *   None
+ *
+ ****************************************************************************/
+
+static void automount_worker(FAR void *arg)
+{
+  FAR struct automounter_state_s *priv = (FAR struct automounter_state_s *)arg;
+  FAR const struct automount_lower_s *lower;
+
+  DEBUGASSERT(priv && priv->lower);
+  lower = priv->lower;
+
+  /* Disable interrupts.  We are commit now and everything must remain
+   * stable.
+   */
+
+  AUTOMOUNT_DISABLE(lower);
+
+  /* Are we mounting or unmounting? */
+
+  if (priv->inserted)
+    {
+      /* We are mounting */
+
+      automount_mount(priv);
+    }
+  else
+    {
+      /* We are unmounting */
+
+      (void)automount_unmount(priv);
+    }
+
+  /* Re-enable interrupts */
+
+  AUTOMOUNT_ENABLE(lower);
+}
+
+/****************************************************************************
+ * Name: automount_interrupt
+ *
+ * Description:
+ *   Called (probably from the interrupt level) when a media change event
+ *   has been detected.
+ *
+ * Input Parameters:
+ *   lower - Persistent board configuration data
+ *   arg - Data associated with the automounter
+ *   inserted - True: Media has been inserted. False: media has been removed
+ *
+ * Returned Value:
+ *   OK is returned on success; a negated errno value is returned on failure.
+ *
+ * Assumptions:
+ *   Interrupts are disabled so that there is no race condition with the
+ *   timer expiry.
+ *
+ ****************************************************************************/
+
+static int automount_interrupt(FAR const struct automount_lower_s *lower,
+                               FAR void *arg, bool inserted)
+{
+  FAR struct automounter_state_s *priv = (FAR struct automounter_state_s *)arg;
+  int ret;
+
+  DEBUGASSERT(lower && priv && priv->lower == lower);
+
+  fllvdbg("inserted=%d\n", inserted);
+
+  /* Cancel any pending work.  We could get called multiple times if, for
+   * example there is bounce in the detection mechanism.  Work is performed
+   * the low priority work queue if it is available.
+   */
+
+  ret = work_cancel(LPWORK, &priv->work);
+  if (ret < 0)
+    {
+      /* NOTE: Currently, work_cancel only returns success */
+
+      fdbg("ERROR: Failed to cancel work: %d\n", ret);
+    }
+
+  /* Set the media insertion/removal state */
+
+  priv->inserted = inserted;
+
+  /* Queue work to occur after a delay.  The delays performs debouncing:
+   * If the insertion/removal detection logic has "chatter", then we may
+   * receive this interrupt numerous times.  Each time, the previous work
+   * will be cancelled (above) and the new work will scheduled with the
+   * delay.  So the final mount operation will not be performed until the
+   * insertion state is stable for that delay.
+   */
+
+  ret = work_queue(LPWORK, &priv->work, automount_worker, priv,
+                   priv->lower->ddelay);
+  if (ret < 0)
+    {
+      /* NOTE: Currently, work_cancel only returns success */
+
+      fdbg("ERROR: Failed to schedule work: %d\n", ret);
+    }
+  else
+    {
+      /* Cancel any retry delays */
+
+      (void)wd_cancel(priv->wdog);
+    }
+
+  return OK;
+}
+
+/****************************************************************************
+ * Public Functions
+ ****************************************************************************/
+
+/****************************************************************************
+ * Name: automount_initialize
+ *
+ * Description:
+ *   Configure the automounter.
+ *
+ * Input Parameters:
+ *   lower - Persistent board configuration data
+ *
+ * Returned Value:
+ *   A void* handle.  The only use for this handle is with auto_uninitialize().
+ *   NULL is returned on any failure.
+ *
+ ****************************************************************************/
+
+FAR void *automount_initialize(FAR const struct automount_lower_s *lower)
+{
+  FAR struct automounter_state_s *priv;
+  int ret;
+
+  fvdbg("lower=%p\n", lower);
+  DEBUGASSERT(lower);
+
+  /* Allocate an automounter state structure */
+
+  priv = (FAR struct automounter_state_s *)
+    kzalloc(sizeof(struct automounter_state_s));
+
+  if (!priv)
+    {
+      fdbg("ERROR: Failed to allocate state structure\n");
+      return NULL;
+    }
+
+  /* Initialize the automounter state structure */
+
+  priv->lower = lower;
+
+  /* Get a timer to handle unmount retries */
+
+  priv->wdog  = wd_create();
+  if (!priv->wdog)
+    {
+      fdbg("ERROR: Failed to create a timer\n");
+      auto_uninitialize(priv);
+      return NULL;
+    }
+
+  /* Attach and enable automounter interrupts */
+
+  ret = AUTOMOUNT_ATTACH(lower, automount_interrupt, priv);
+  if (ret < 0)
+    {
+      fdbg("ERROR: Failed to attach automount interrupt: %d\n", ret);
+      auto_uninitialize(priv);
+      return NULL;
+    }
+
+  AUTOMOUNT_ENABLE(lower);
+  return priv;
+}
+
+/****************************************************************************
+ * Name: auto_uninitialize
+ *
+ * Description:
+ *   Stop the automounter and free resources that it used.
+ *
+ * Input Parameters:
+ *   handle - The value previously returned by automount_initialize();
+ *
+ * Returned Value:
+ *   None
+ *
+ ****************************************************************************/
+
+void auto_uninitialize(FAR void *handle)
+{
+  FAR struct automounter_state_s *priv = (FAR struct automounter_state_s *)handle;
+  FAR const struct automount_lower_s *lower;
+
+  DEBUGASSERT(priv && priv->lower);
+  lower = priv->lower;
+
+  /* Disable and detach interrupts */
+
+  AUTOMOUNT_DISABLE(lower);
+  (void)AUTOMOUNT_DETACH(lower);
+
+  /* Release resources */
+
+  (void)wd_delete(priv->wdog);
+
+  /* And free the state structure */
+
+  kfree(priv);
+}
diff --git a/nuttx/include/nuttx/fs/automount.h b/nuttx/include/nuttx/fs/automount.h
new file mode 100644
index 000000000..ab4a51199
--- /dev/null
+++ b/nuttx/include/nuttx/fs/automount.h
@@ -0,0 +1,191 @@
+/****************************************************************************
+ * include/nuttx/audio/automount.h
+ *
+ *   Copyright (C) 2014 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 __INCLUDE_NUTTX_AUDIO_AUTOMOUNT_H
+#define __INCLUDE_NUTTX_AUDIO_AUTOMOUNT_H
+
+/****************************************************************************
+ * Included Files
+ ****************************************************************************/
+
+#include <stdint.h>
+#include <stdbool.h>
+
+#include <nuttx/irq.h>
+
+#ifdef CONFIG_FS_AUTOMOUNTER
+
+/****************************************************************************
+ * Pre-processor Definitions
+ ****************************************************************************/
+/* Configuration ************************************************************
+ * Automounter configuration
+ *   CONFIG_FS_AUTOMOUNTER - Enables automount support
+ *
+ * Prequisites:
+ *   CONFIG_SCHED_WORKQUEUE -  Work queue support is required
+ *   And others that would only matter if you are working in a very minimal
+ *   configuration.
+ */
+
+/* Helper macros ************************************************************/
+
+#define AUTOMOUNT_ATTACH(s,isr,arg) ((s)->attach(s,isr,arg))
+#define AUTOMOUNT_DETACH(s)         ((s)->attach(s,NULL,NULL))
+#define AUTOMOUNT_ENABLE(s)         ((s)->enable(s,true))
+#define AUTOMOUNT_DISABLE(s)        ((s)->enable(s,false))
+
+/****************************************************************************
+ * Public Types
+ ****************************************************************************/
+/* This is the type of the automount media change handler.  The lower level
+ * code will intercept the interrupt and provide the upper level with the
+ * private data that was provided when the interrupt was attached and will
+ * also provide an indication if the media was inserted or removed.
+ */
+
+struct automount_lower_s; /* Forward reference.  Defined below */
+
+typedef CODE int
+  (*automount_handler_t)(FAR const struct automount_lower_s *lower,
+                         FAR void *arg, bool inserted);
+
+/* A reference to a structure of this type must be passed to the FS
+ * automounter.  This structure provides information about the volume to be
+ * mounted and provides board-specific hooks.
+ *
+ * Memory for this structure is provided by the caller.  It is not copied
+ * by the automounter and is presumed to persist while the automounter
+ * is active.
+ */
+
+struct automount_lower_s
+{
+  /* Volume characterization */
+
+  FAR const char *fstype;     /* Type of file system */
+  FAR const char *blockdev;   /* Path to the block device */
+  FAR const char *mountpoint; /* Location to mount the volume */
+
+  /* Debounce delay in system clock ticks.  Automount operation will not
+   * be performed until the insertion/removal state has been unchanges
+   * for this duration.
+   */
+
+  uint32_t ddelay;
+
+  /* Unmount delay time in sysem clock ticks.  If a volume has open
+   * references at the time that the media is removed, then we will be
+   * unable to unmount it.  In that case, hopefully, the clients of the
+   * mount will eventually fail with file access errors and eventually close
+   * their references.  So, at some time later, it should be possible to
+   * unmount the volume.  This delay specifies the time between umount
+   * retries.
+   */
+
+  uint32_t udelay;
+
+  /* Interrupt related operations all hidden behind callbacks to isolate the
+   * automounter from differences in interrupt handling by varying boards
+   * and MCUs.  Board interrupts should be configured both insertion and
+   * removal of the media can be detected.
+   *
+   * attach  - Attach or detach the media change interrupt handler to the
+   *           board level interrupt
+   * enable  - Enable or disable the media change interrupt
+   */
+
+  CODE int  (*attach)(FAR const struct automount_lower_s *lower,
+                      automount_handler_t isr, FAR void *arg);
+  CODE void (*enable)(FAR const struct automount_lower_s *lower,
+                      bool enable);
+};
+
+/****************************************************************************
+ * Public Data
+ ****************************************************************************/
+
+#ifdef __cplusplus
+#define EXTERN extern "C"
+extern "C"
+{
+#else
+#define EXTERN extern
+#endif
+
+/****************************************************************************
+ * Public Function Prototypes
+ ****************************************************************************/
+
+/****************************************************************************
+ * Name: automount_initialize
+ *
+ * Description:
+ *   Configure the automounter.
+ *
+ * Input Parameters:
+ *   lower - Persistent board configuration data
+ *
+ * Returned Value:
+ *   A void* handle.  The only use for this handle is with auto_uninitialize().
+ *   NULL is returned on any failure.
+ *
+ ****************************************************************************/
+
+FAR void *automount_initialize(FAR const struct automount_lower_s *lower);
+
+/****************************************************************************
+ * Name: auto_uninitialize
+ *
+ * Description:
+ *   Stop the automounter and free resources that it used.
+ *
+ * Input Parameters:
+ *   handle - The value previously returned by automount_initialize();
+ *
+ * Returned Value:
+ *   None
+ *
+ ****************************************************************************/
+
+void auto_uninitialize(FAR void *handle);
+
+#undef EXTERN
+#ifdef __cplusplus
+}
+#endif
+
+#endif /* CONFIG_FS_AUTOMOUNTER */
+#endif /* __INCLUDE_NUTTX_AUDIO_AUTOMOUNT_H */