Add support for a USB HID mouse. Untested on initial check-in

1 files changed, 2292 insertions, 0 deletions

diff --git a/nuttx/drivers/usbhost/usbhost_hidmouse.c b/nuttx/drivers/usbhost/usbhost_hidmouse.c
new file mode 100644
index 000000000..63f66fa6a
--- /dev/null
+++ b/nuttx/drivers/usbhost/usbhost_hidmouse.c
@@ -0,0 +1,2292 @@
+/****************************************************************************
+ * drivers/usbhost/usbhost_hidmouse.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>
+
+#include <sys/types.h>
+#include <stdbool.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <unistd.h>
+#include <string.h>
+#include <poll.h>
+#include <semaphore.h>
+#include <time.h>
+#include <fcntl.h>
+#include <assert.h>
+#include <errno.h>
+#include <fixedmath.h>
+#include <debug.h>
+
+#include <nuttx/kmalloc.h>
+#include <nuttx/fs/fs.h>
+#include <nuttx/arch.h>
+#include <nuttx/wqueue.h>
+
+#include <nuttx/usb/usb.h>
+#include <nuttx/usb/usbhost.h>
+#include <nuttx/usb/hid.h>
+
+#include <nuttx/input/touchscreen.h>
+
+/* Don't compile if prerequisites are not met */
+
+#if defined(CONFIG_USBHOST) && !defined(CONFIG_USBHOST_INT_DISABLE) && CONFIG_NFILE_DESCRIPTORS > 0
+
+/****************************************************************************
+ * Pre-processor Definitions
+ ****************************************************************************/
+/* Configuration ************************************************************/
+/* This determines how often the USB mouse will be polled in units of
+ * of microseconds.  The default is 100MS.
+ */
+
+#ifndef CONFIG_HIDMOUSE_POLLUSEC
+#  define CONFIG_HIDMOUSE_POLLUSEC (100*1000)
+#endif
+
+/* Worker thread is needed, unfortunately, to handle some cornercase failure
+ * conditions.  This is kind of wasteful and begs for a re-design.
+ */
+
+#ifndef CONFIG_SCHED_WORKQUEUE
+#  warning "Worker thread support is required (CONFIG_SCHED_WORKQUEUE)"
+#endif
+
+/* Signals must not be disabled as they are needed by usleep.  Need to have
+ * CONFIG_DISABLE_SIGNALS=n
+ */
+
+#ifdef CONFIG_DISABLE_SIGNALS
+#  warning "Signal support is required (CONFIG_DISABLE_SIGNALS)"
+#endif
+
+/* Provide some default values for other configuration settings */
+
+#ifndef CONFIG_HIDMOUSE_XMAX
+#  define CONFIG_HIDMOUSE_XMAX 320
+#endif
+
+#define HIDMOUSE_XMAX_B16 (CONFIG_HIDMOUSE_XMAX << 16)
+
+#ifndef CONFIG_HIDMOUSE_YMAX
+#  define CONFIG_HIDMOUSE_YMAX 240
+#endif
+
+#define HIDMOUSE_YMAX_B16 (CONFIG_HIDMOUSE_YMAX << 16)
+
+#ifndef CONFIG_HIDMOUSE_XSCALE
+#  define CONFIG_HIDMOUSE_XSCALE 0x00010000
+#endif
+
+#ifndef CONFIG_HIDMOUSE_YSCALE
+#  define CONFIG_HIDMOUSE_YSCALE 0x00010000
+#endif
+
+#ifndef CONFIG_HIDMOUSE_XTHRESH
+#  define CONFIG_HIDMOUSE_XTHRESH 12
+#endif
+
+#define HIDMOUSE_XTHRESH_B16 (CONFIG_HIDMOUSE_XTHRESH << 16)
+
+#ifndef CONFIG_HIDMOUSE_YTHRESH
+#  define CONFIG_HIDMOUSE_YTHRESH 12
+#endif
+
+#define HIDMOUSE_YTHRESH_B16 (CONFIG_HIDMOUSE_YTHRESH << 16)
+
+#ifndef CONFIG_HIDMOUSE_DEFPRIO
+#  define CONFIG_HIDMOUSE_DEFPRIO 50
+#endif
+
+#ifndef CONFIG_HIDMOUSE_STACKSIZE
+#  define CONFIG_HIDMOUSE_STACKSIZE 1024
+#endif
+
+#ifndef CONFIG_HIDMOUSE_NPOLLWAITERS
+#  define CONFIG_HIDMOUSE_NPOLLWAITERS 2
+#endif
+
+/* This is a value for the threshold that guarantees a big difference on the
+ * first left button (but can't overflow).
+ */
+
+#define INVALID_POSITION_B16 (0x7fffffff)
+
+/* Driver support ***********************************************************/
+/* This format is used to construct the /dev/mouse[n] device driver path.  It
+ * defined here so that it will be used consistently in all places.
+ */
+
+#define DEV_FORMAT          "/dev/mouse%d"
+#define DEV_NAMELEN         13
+
+/* Used in usbhost_cfgdesc() */
+
+#define USBHOST_IFFOUND     0x01 /* Required I/F descriptor found */
+#define USBHOST_EPINFOUND   0x02 /* Required interrupt IN EP descriptor found */
+#define USBHOST_ALLFOUND    (USBHOST_IFFOUND|USBHOST_EPINFOUND)
+
+#define USBHOST_MAX_CREFS   0x7fff
+
+/* Debug ********************************************************************/
+/* Both CONFIG_DEBUG_INPUT and CONFIG_DEBUG_USB could apply to this file.
+ * We assume here that CONFIG_DEBUG_INPUT might be enabled separately, but
+ * CONFIG_DEBUG_USB implies both.
+ */
+
+#ifndef CONFIG_DEBUG_INPUT
+#  undef  idbg
+#  define idbg    udbg
+#  undef  illdbg
+#  define illdbg  ulldbg
+#  undef  ivdbg
+#  define ivdbg   uvdbg
+#  undef  illvdbg
+#  define illvdbg ullvdbg
+#endif
+
+/****************************************************************************
+ * Private Types
+ ****************************************************************************/
+
+/* This describes the state of one event */
+
+enum mouse_button_e
+{
+  BUTTON_NONE = 0,                      /* No button pressed */
+  BUTTON_PRESSED,                       /* Left buffer pressed */
+  BUTTON_MOVE,                          /* Same button press, possibly different position */
+  BUTTON_RELEASED                       /* Left button released */
+};
+
+/* This structure describes the results of one mouse sample.  Since this
+ * emulates a touchscreen, only the mouse left button is used.
+ */
+
+struct mouse_sample_s
+{
+  uint8_t  id;                          /* Sampled touch point ID */
+  uint8_t  event;                       /* Button state (see enum mouse_button_e) */
+  bool     valid;                       /* True: x,y contain valid, sampled data */
+  uint16_t x;                           /* Measured X position */
+  uint16_t y;                           /* Measured Y position */
+};
+
+/* This structure contains the internal, private state of the USB host
+ * mouse storage class.
+ */
+
+struct usbhost_state_s
+{
+  /* This is the externally visible portion of the state */
+
+  struct usbhost_class_s  class;
+
+  /* This is an instance of the USB host driver bound to this class instance */
+
+  struct usbhost_driver_s *drvr;
+
+  /* The remainder of the fields are provide o the mouse class driver */
+
+  volatile bool           disconnected; /* TRUE: Device has been disconnected */
+  volatile bool           polling;      /* TRUE: Poll thread is running */
+  volatile bool           open;         /* TRUE: The mouse device is open */
+  volatile bool           waiting;      /* TRUE: waiting for mouse data */
+  volatile bool           valid;        /* TRUE: New sample data is available */
+  uint8_t                 devno;        /* Minor number in the /dev/mouse[n] device */
+  uint8_t                 ifno;         /* Interface number */
+  uint8_t                 nwaiters;     /* Number of threads waiting for mouse data */
+  uint8_t                 id;           /* Current "touch" point ID */
+  int16_t                 crefs;        /* Reference count on the driver instance */
+  sem_t                   exclsem;      /* Used to maintain mutual exclusive access */
+  sem_t                   waitsem;      /* Used to wait for mouse data */
+  FAR uint8_t            *tbuffer;      /* The allocated transfer buffer */
+  b16_t                   xpos;         /* Current integrated X position */
+  b16_t                   ypos;         /* Current integrated Y position */
+  b16_t                   xlast;        /* Last reported X position */
+  b16_t                   ylast;        /* Last reported Y position */
+  size_t                  tbuflen;      /* Size of the allocated transfer buffer */
+  pid_t                   pollpid;      /* PID of the poll task */
+  struct work_s           work;         /* For cornercase error handling by the worker thread */
+  struct mouse_sample_s   sample;      /* Last sampled mouse data */
+  usbhost_ep_t            epin;         /* Interrupt IN endpoint */
+
+  /* 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_HIDMOUSE_NPOLLWAITERS];
+#endif
+};
+
+/****************************************************************************
+ * Private Function Prototypes
+ ****************************************************************************/
+
+/* Semaphores */
+
+static void usbhost_takesem(sem_t *sem);
+#define usbhost_givesem(s) sem_post(s);
+
+/* Polling support */
+
+#ifndef CONFIG_DISABLE_POLL
+static void usbhost_pollnotify(FAR struct usbhost_state_s *dev);
+#else
+#  define usbhost_pollnotify(dev)
+#endif
+
+/* Memory allocation services */
+
+static inline FAR struct usbhost_state_s *usbhost_allocclass(void);
+static inline void usbhost_freeclass(FAR struct usbhost_state_s *class);
+
+/* Device name management */
+
+static int usbhost_allocdevno(FAR struct usbhost_state_s *priv);
+static void usbhost_freedevno(FAR struct usbhost_state_s *priv);
+static inline void usbhost_mkdevname(FAR struct usbhost_state_s *priv, char *devname);
+
+/* Mouse polling thread */
+
+static void usbhost_destroy(FAR void *arg);
+static void usbhost_notify(FAR struct usbhost_state_s *priv);
+static int usbhost_mouse_poll(int argc, char *argv[]);
+static int usbhost_sample(FAR struct usbhost_state_s *priv,
+                          FAR struct mouse_sample_s *sample);
+static int usbhost_waitsample(FAR struct usbhost_state_s *priv,
+                              FAR struct mouse_sample_s *sample);
+
+/* Helpers for usbhost_connect() */
+
+static inline int usbhost_cfgdesc(FAR struct usbhost_state_s *priv,
+                                  FAR const uint8_t *configdesc, int desclen,
+                                  uint8_t funcaddr);
+static inline int usbhost_devinit(FAR struct usbhost_state_s *priv);
+
+/* (Little Endian) Data helpers */
+
+static inline uint16_t usbhost_getle16(const uint8_t *val);
+static inline void usbhost_putle16(uint8_t *dest, uint16_t val);
+static inline uint32_t usbhost_getle32(const uint8_t *val);
+#if 0 /* Not used */
+static void usbhost_putle32(uint8_t *dest, uint32_t val);
+#endif
+
+/* Transfer descriptor memory management */
+
+static inline int usbhost_tdalloc(FAR struct usbhost_state_s *priv);
+static inline int usbhost_tdfree(FAR struct usbhost_state_s *priv);
+
+/* struct usbhost_registry_s methods */
+
+static struct usbhost_class_s *usbhost_create(FAR struct usbhost_driver_s *drvr,
+                                              FAR const struct usbhost_id_s *id);
+
+/* struct usbhost_class_s methods */
+
+static int usbhost_connect(FAR struct usbhost_class_s *class,
+                           FAR const uint8_t *configdesc, int desclen,
+                           uint8_t funcaddr);
+static int usbhost_disconnected(FAR struct usbhost_class_s *class);
+
+/* Driver methods.  We export the mouse as a standard character driver */
+
+static int usbhost_open(FAR struct file *filep);
+static int usbhost_close(FAR struct file *filep);
+static ssize_t usbhost_read(FAR struct file *filep,
+                            FAR char *buffer, size_t len);
+static ssize_t usbhost_write(FAR struct file *filep,
+                             FAR const char *buffer, size_t len);
+#ifndef CONFIG_DISABLE_POLL
+static int usbhost_poll(FAR struct file *filep, FAR struct pollfd *fds,
+                        bool setup);
+#endif
+
+/****************************************************************************
+ * Private Data
+ ****************************************************************************/
+
+/* This structure provides the registry entry ID information that will  be
+ * used to associate the USB host mouse class driver to a connected USB
+ * device.
+ */
+
+static const const struct usbhost_id_s g_hidmouse_id =
+{
+  USB_CLASS_HID,           /* base     */
+  USBHID_SUBCLASS_BOOTIF,  /* subclass */
+  USBHID_PROTOCOL_MOUSE,   /* proto    */
+  0,                       /* vid      */
+  0                        /* pid      */
+};
+
+/* This is the USB host storage class's registry entry */
+
+static struct usbhost_registry_s g_hidmouse =
+{
+  NULL,                    /* flink     */
+  usbhost_create,          /* create    */
+  1,                       /* nids      */
+  &g_hidmouse_id           /* id[]      */
+};
+
+static const struct file_operations g_hidmouse_fops =
+{
+  usbhost_open,            /* open      */
+  usbhost_close,           /* close     */
+  usbhost_read,            /* read      */
+  usbhost_write,           /* write     */
+  0,                       /* seek      */
+  0                        /* ioctl     */
+#ifndef CONFIG_DISABLE_POLL
+  , usbhost_poll           /* poll      */
+#endif
+};
+
+/* This is a bitmap that is used to allocate device names /dev/mouse0-31. */
+
+static uint32_t                g_devinuse;
+
+/* The following are used to managed the class creation operation */
+
+static sem_t                   g_exclsem; /* For mutually exclusive thread creation */
+static sem_t                   g_syncsem; /* Thread data passing interlock */
+static struct usbhost_state_s *g_priv;    /* Data passed to thread */
+
+/****************************************************************************
+ * Private Functions
+ ****************************************************************************/
+
+/****************************************************************************
+ * Name: usbhost_takesem
+ *
+ * Description:
+ *   This is just a wrapper to handle the annoying behavior of semaphore
+ *   waits that return due to the receipt of a signal.
+ *
+ ****************************************************************************/
+
+static void usbhost_takesem(sem_t *sem)
+{
+  /* Take the semaphore (perhaps waiting) */
+
+  while (sem_wait(sem) != 0)
+    {
+      /* The only case that an error should occur here is if the wait was
+       * awakened by a signal.
+       */
+
+      ASSERT(errno == EINTR);
+    }
+}
+
+/****************************************************************************
+ * Name: usbhost_pollnotify
+ ****************************************************************************/
+
+#ifndef CONFIG_DISABLE_POLL
+static void usbhost_pollnotify(FAR struct usbhost_state_s *priv)
+{
+  int i;
+
+  for (i = 0; i < CONFIG_HIDMOUSE_NPOLLWAITERS; i++)
+    {
+      struct pollfd *fds = priv->fds[i];
+      if (fds)
+        {
+          fds->revents |= (fds->events & POLLIN);
+          if (fds->revents != 0)
+            {
+              uvdbg("Report events: %02x\n", fds->revents);
+              sem_post(fds->sem);
+            }
+        }
+    }
+}
+#endif
+
+/****************************************************************************
+ * Name: usbhost_allocclass
+ *
+ * Description:
+ *   This is really part of the logic that implements the create() method
+ *   of struct usbhost_registry_s.  This function allocates memory for one
+ *   new class instance.
+ *
+ * Input Parameters:
+ *   None
+ *
+ * Returned Values:
+ *   On success, this function will return a non-NULL instance of struct
+ *   usbhost_class_s.  NULL is returned on failure; this function will
+ *   will fail only if there are insufficient resources to create another
+ *   USB host class instance.
+ *
+ ****************************************************************************/
+
+static inline FAR struct usbhost_state_s *usbhost_allocclass(void)
+{
+  FAR struct usbhost_state_s *priv;
+
+  DEBUGASSERT(!up_interrupt_context());
+  priv = (FAR struct usbhost_state_s *)kmalloc(sizeof(struct usbhost_state_s));
+  uvdbg("Allocated: %p\n", priv);;
+  return priv;
+}
+
+/****************************************************************************
+ * Name: usbhost_freeclass
+ *
+ * Description:
+ *   Free a class instance previously allocated by usbhost_allocclass().
+ *
+ * Input Parameters:
+ *   class - A reference to the class instance to be freed.
+ *
+ * Returned Values:
+ *   None
+ *
+ ****************************************************************************/
+
+static inline void usbhost_freeclass(FAR struct usbhost_state_s *class)
+{
+  DEBUGASSERT(class != NULL);
+
+  /* Free the class instance. */
+
+  uvdbg("Freeing: %p\n", class);;
+  kfree(class);
+}
+
+/****************************************************************************
+ * Name: Device name management
+ *
+ * Description:
+ *   Some tiny functions to coordinate management of device names.
+ *
+ ****************************************************************************/
+
+static int usbhost_allocdevno(FAR struct usbhost_state_s *priv)
+{
+  irqstate_t flags;
+  int devno;
+
+  flags = irqsave();
+  for (devno = 0; devno < 26; devno++)
+    {
+      uint32_t bitno = 1 << devno;
+      if ((g_devinuse & bitno) == 0)
+        {
+          g_devinuse |= bitno;
+          priv->devno = devno;
+          irqrestore(flags);
+          return OK;
+        }
+    }
+
+  irqrestore(flags);
+  return -EMFILE;
+}
+
+static void usbhost_freedevno(FAR struct usbhost_state_s *priv)
+{
+  int devno = priv->devno;
+
+  if (devno >= 0 && devno < 26)
+    {
+      irqstate_t flags = irqsave();
+      g_devinuse &= ~(1 << devno);
+      irqrestore(flags);
+    }
+}
+
+static inline void usbhost_mkdevname(FAR struct usbhost_state_s *priv, char *devname)
+{
+  (void)snprintf(devname, DEV_NAMELEN, DEV_FORMAT, priv->devno);
+}
+
+/****************************************************************************
+ * Name: usbhost_destroy
+ *
+ * Description:
+ *   The USB device has been disconnected and the reference count on the USB
+ *   host class instance has gone to 1.. Time to destroy the USB host class
+ *   instance.
+ *
+ * Input Parameters:
+ *   arg - A reference to the class instance to be destroyed.
+ *
+ * Returned Values:
+ *   None
+ *
+ ****************************************************************************/
+
+static void usbhost_destroy(FAR void *arg)
+{
+  FAR struct usbhost_state_s *priv = (FAR struct usbhost_state_s *)arg;
+  char devname[DEV_NAMELEN];
+
+  DEBUGASSERT(priv != NULL);
+  uvdbg("crefs: %d\n", priv->crefs);
+
+  /* Unregister the driver */
+
+  uvdbg("Unregister driver\n");
+  usbhost_mkdevname(priv, devname);
+  (void)unregister_driver(devname);
+
+  /* Release the device name used by this connection */
+
+  usbhost_freedevno(priv);
+
+  /* Free the interrupt endpoints */
+
+  if (priv->epin)
+    {
+      DRVR_EPFREE(priv->drvr, priv->epin);
+    }
+
+  /* Free any transfer buffers */
+
+  usbhost_tdfree(priv);
+
+  /* Destroy the semaphores */
+
+  sem_destroy(&priv->exclsem);
+  sem_destroy(&priv->waitsem);
+
+  /* Disconnect the USB host device */
+
+  DRVR_DISCONNECT(priv->drvr);
+
+  /* And free the class instance.  Hmmm.. this may execute on the worker
+   * thread and the work structure is part of what is getting freed.  That
+   * should be okay because once the work contained is removed from the
+   * queue, it should not longer be accessed by the worker thread.
+   */
+
+  usbhost_freeclass(priv);
+}
+
+/****************************************************************************
+ * Name: usbhost_notify
+ *
+ * Description:
+ *   Wake any threads waiting for mouse data
+ *
+ * Input Paramters:
+ *   priv - A reference to the mouse state structure.
+ *
+ * Returned Value:
+ *   None
+ *
+ ****************************************************************************/
+
+static void usbhost_notify(FAR struct usbhost_state_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)
+    {
+      sem_post(&priv->waitsem);
+    }
+
+  /* If there are threads waiting on poll() for mouse 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_HIDMOUSE_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: usbhost_mouse_poll
+ *
+ * Description:
+ *   Periodically check for new mouse data.
+ *
+ * Input Parameters:
+ *   arg - A reference to the class instance to be destroyed.
+ *
+ * Returned Values:
+ *   None
+ *
+ ****************************************************************************/
+
+static int usbhost_mouse_poll(int argc, char *argv[])
+{
+  FAR struct usbhost_state_s *priv;
+  FAR struct usb_ctrlreq_s   *ctrlreq;
+  int32_t                     xdisp;
+  int32_t                     ydisp;
+  b16_t                       xpos;
+  b16_t                       ypos;
+  b16_t                       xdiff;
+  b16_t                       ydiff;
+#if defined(CONFIG_DEBUG_USB) && defined(CONFIG_DEBUG_VERBOSE)
+  unsigned int                npolls = 0;
+#endif
+  unsigned int                nerrors = 0;
+  int                         ret;
+
+  uvdbg("Started\n");
+
+  /* Synchronize with the start-up logic.  Get the private instance, re-start
+   * the start-up logic, and wait a bit to make sure that all of the class
+   * creation logic has a chance to run to completion.
+   *
+   * NOTE: that the reference count is incremented here.  Therefore, we know
+   * that the driver data structure will remain stable while this thread is
+   * running.
+   */
+
+  priv = g_priv;
+  DEBUGASSERT(priv != NULL);
+
+  priv->polling = true;
+  priv->crefs++;
+  usbhost_givesem(&g_syncsem);
+  sleep(1);
+
+  /* Loop here until the device is disconnected */
+
+  uvdbg("Entering poll loop\n");
+
+  while (!priv->disconnected)
+    {
+      /* Make sure that we have exclusive access to the private data
+       * structure. There may now be other tasks with the character driver
+       * open and actively trying to interact with the class driver.
+       */
+
+      usbhost_takesem(&priv->exclsem);
+
+      /* Format the HID report request:
+       *
+       *   bmRequestType 10100001
+       *   bRequest      GET_REPORT (0x01)
+       *   wValue        Report Type and Report Index
+       *   wIndex        Interface Number
+       *   wLength       Descriptor Length
+       *   Data          Descriptor Data
+       */
+
+      ctrlreq       = (struct usb_ctrlreq_s *)priv->tbuffer;
+      ctrlreq->type = USB_REQ_DIR_IN|USB_REQ_TYPE_CLASS|USB_REQ_RECIPIENT_INTERFACE;
+      ctrlreq->req  = USBHID_REQUEST_GETREPORT;
+
+      usbhost_putle16(ctrlreq->value, (USBHID_REPORTTYPE_INPUT << 8));
+      usbhost_putle16(ctrlreq->index, priv->ifno);
+      usbhost_putle16(ctrlreq->len,   sizeof(struct usbhid_mousereport_s));
+
+      /* Send HID report request */
+
+      ret = DRVR_CTRLIN(priv->drvr, ctrlreq, priv->tbuffer);
+      usbhost_givesem(&priv->exclsem);
+
+      /* Check for errors -- Bail if an excessive number of errors
+       * are encountered.
+       */
+
+      if (ret != OK)
+        {
+          nerrors++;
+          udbg("ERROR: GETREPORT/INPUT, DRVR_CTRLIN returned: %d/%d\n",
+               ret, nerrors);
+
+          if (nerrors > 200)
+            {
+              udbg("Too many errors... aborting: %d\n", nerrors);
+              break;
+            }
+        }
+
+      /* The report was received correctly.  But ignore the mouse data if no
+       * task has opened the driver.
+       */
+
+      else if (priv->open)
+        {
+          FAR struct usbhid_mousereport_s *rpt;
+
+          /* Get exclusive access to the mouse state data */
+
+          usbhost_takesem(&priv->exclsem);
+
+          /* Get the HID mouse report */
+
+          rpt = (struct usbhid_mousereport_s *)priv->tbuffer;
+
+          /* The following logic performs an constant integration of the
+           * mouse X/Y displacement data in order to keep the X/Y positional
+           * data current.
+           */
+
+          /* Sign extend the mouse X position.  We do this manually because
+           * some architectures do not support signed character types and
+           * some compilers may  be configured to treat all characters as
+           * unsigned.
+           */
+
+#ifdef CONFIG_HIDMOUSE_SWAPXY
+          xdisp = rpt->xdisp;
+          if ((rpt->xdisp & 0x80) != 0)
+            {
+              xdisp |= 0xffffff00;
+            }
+#else
+          xdisp = rpt->ydisp;
+          if ((rpt->ydisp & 0x80) != 0)
+            {
+              ydisp |= 0xffffff00;
+            }
+#endif
+
+          /* Scale the X displacement and determine the new X position */
+
+          xpos = priv->xpos + CONFIG_HIDMOUSE_XSCALE * xdisp;
+
+          /* Make sure that the scaled X position does not exceed the
+           * maximum.
+           */
+
+          if (xpos > HIDMOUSE_XMAX_B16)
+            {
+              xpos = HIDMOUSE_XMAX_B16;
+            }
+
+          /* Do the same for the Y position */
+
+#ifdef CONFIG_HIDMOUSE_SWAPXY
+          ydisp = rpt->ydisp;
+          if ((rpt->ydisp & 0x80) != 0)
+            {
+              ydisp |= 0xffffff00;
+            }
+#else
+          ydisp = rpt->xdisp;
+          if ((rpt->xdisp & 0x80) != 0)
+            {
+              xdisp |= 0xffffff00;
+            }
+#endif
+          ypos = priv->ypos + CONFIG_HIDMOUSE_YSCALE * ydisp;
+
+          if (ypos > HIDMOUSE_YMAX_B16)
+            {
+              ypos = HIDMOUSE_YMAX_B16;
+            }
+
+          /* Check if the left button is pressed */
+
+          if ((rpt->buttons & USBHID_MOUSEIN_BUTTON1) == 0)
+            {
+              /* The left button is not pressed.. reset thresholding
+               * variables.
+               */
+
+              priv->xlast = INVALID_POSITION_B16;
+              priv->ylast = INVALID_POSITION_B16;
+
+              /* Ignore the report if the button was not pressed last
+               * time (BUTTON_NONE == button released and already
+               * reported; BUTTON_RELEASED == button released, but not
+               * yet reported)
+               */
+
+              if (priv->sample.event == BUTTON_NONE ||
+                  priv->sample.event == BUTTON_RELEASED)
+
+                {
+                  goto ignored;
+                }
+
+              /* The left button has just been released.  NOTE: We know from
+               * a previous test, that this is a button release condition.
+               * This will be changed to BUTTON_NONE after the button release
+               * has been reported.
+               */
+
+              priv->sample.event = BUTTON_RELEASED;
+            }
+
+          /* It is a left button press event.  If the last button release
+           * event has not been processed yet, then we have to ignore the
+           * button press event (or else it will look like a drag event)
+           */
+
+          else if (priv->sample.event == BUTTON_RELEASED)
+            {
+              /* 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 and wait for the next sample data.
+               */
+
+              goto ignored;
+            }
+
+          /* Handle left-button down events */
+
+          else
+            {
+              /* If this is the first left button press report, then
+               * report that event.  If event == BUTTON_PRESSED, it will
+               * be  set to set to BUTTON_MOVE after the button press is
+               * first sampled.
+               */
+
+              if (priv->sample.event != BUTTON_MOVE)
+                {
+                  /* First button press */
+
+                  priv->sample.event = BUTTON_PRESSED;
+                }
+
+              /* Otherwise, 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.
+               */
+
+             else
+               {
+                  if (xpos > priv->xlast)
+                    {
+                      xdiff = xpos - priv->xlast;
+                    }
+                  else
+                    {
+                      xdiff = priv->xlast - xpos;
+                    }
+
+                  if (xdiff < HIDMOUSE_XTHRESH_B16)
+                    {
+                      /* Little or no change in the X diretion, check the
+                       * Y direction.
+                       */
+
+                      if (ypos > priv->ylast)
+                        {
+                          ydiff = ypos - priv->ylast;
+                        }
+                      else
+                        {
+                          ydiff = priv->ylast - ypos;
+                        }
+
+                      if (ydiff < HIDMOUSE_YTHRESH_B16)
+                        {
+                          /* Little or no change in either direction... don't
+                           * report anything.
+                           */
+
+                          goto ignored;
+                        }
+                    }
+                }
+
+              /* We get here when the left button is first pressed, or when
+               * it has been held and dragged for a distance exceeding a
+               * threshold.
+               *
+               * Snap to the new x/y position for subsequent thresholding */
+
+              priv->xlast = xpos;
+              priv->ylast = ypos;
+            }
+
+          /* We get here when either the left button is released, pressed
+           * or dragged.  We are going to report the mouse event. Update the
+           * sample X/Y positions (the sample event state was set by the
+           * above logic.
+           */
+
+          priv->sample.x = b16toi(xpos);
+          priv->sample.y = b16toi(ypos);
+
+          /* The X/Y positional data is now valid */
+
+          priv->sample.valid = true;
+
+          /* Indicate the availability of new sample data for this ID */
+
+          priv->sample.id = priv->id;
+          priv->valid = true;
+
+          /* Notify any waiters that new HIDMOUSE data is available */
+
+          usbhost_notify(priv);
+        }
+
+      /* This mouse event will not be reported */
+
+ignored:
+      /* Release our lock on the state structure */
+
+      usbhost_givesem(&priv->exclsem);
+
+      /* If USB debug is on, then provide some periodic indication that
+       * polling is still happening.
+       */
+
+#if defined(CONFIG_DEBUG_USB) && defined(CONFIG_DEBUG_VERBOSE)
+      npolls++;
+      if ((npolls & 31) == 0)
+        {
+          udbg("Still polling: %d\n", npolls);
+        }
+#endif
+      /* Wait for the required amount (or until a signal is received).  We
+       * will wake up when either the delay elapses or we are signalled that
+       * the device has been disconnected.
+       */
+
+      usleep(CONFIG_HIDMOUSE_POLLUSEC);
+    }
+
+  /* We get here when the driver is removed.. or when too many errors have
+   * been encountered.
+   *
+   * Make sure that we have exclusive access to the private data structure.
+   * There may now be other tasks with the character driver open and actively
+   * trying to interact with the class driver.
+   */
+
+  usbhost_takesem(&priv->exclsem);
+
+  /* Indicate that we are no longer running and decrement the reference
+   * count help by this thread.  If there are no other users of the class,
+   * we can destroy it now.  Otherwise, we have to wait until the all
+   * of the file descriptors are closed.
+   */
+
+  udbg("Mouse removed, polling halted\n");
+  priv->polling = false;
+  if (--priv->crefs < 2)
+    {
+      /* Destroy the instance (while we hold the semaphore!) */
+
+      usbhost_destroy(priv);
+    }
+  else
+    {
+      /* No, we will destroy the driver instance when it is finally closed */
+
+      usbhost_givesem(&priv->exclsem);
+    }
+
+  return 0;
+}
+
+/****************************************************************************
+ * Name: usbhost_sample
+ *
+ * Description:
+ *   Check if mouse data is available
+ *
+ ****************************************************************************/
+
+static int usbhost_sample(FAR struct usbhost_state_s *priv,
+                          FAR struct mouse_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 mouse data available? */
+
+  if (priv->valid)
+    {
+      /* Return a copy of the sampled data. */
+
+      memcpy(sample, &priv->sample, sizeof(struct mouse_sample_s ));
+
+      /* Now manage state transitions */
+
+      if (sample->event == BUTTON_RELEASED)
+        {
+          /* Next.. No button press.  Increment the ID so that next event ID
+           * will be unique.  X/Y positions are no longer valid.
+           */
+
+          priv->sample.event = BUTTON_NONE;
+          priv->sample.valid = false;
+          priv->id++;
+        }
+      else if (sample->event == BUTTON_PRESSED)
+       {
+          /* First report -- next report will be a movement */
+
+         priv->sample.event = BUTTON_MOVE;
+       }
+
+      priv->valid = false;
+      ret = OK;
+    }
+
+  irqrestore(flags);
+  return ret;
+}
+
+/****************************************************************************
+ * Name: usbhost_waitsample
+ *
+ * Description:
+ *   Wait for the next valid mouse sample
+ *
+ * Input Parameters:
+ *    priv   - HID mouse state instance
+ *    sample - The location to regurn the sample data
+ *
+ ****************************************************************************/
+
+static int usbhost_waitsample(FAR struct usbhost_state_s *priv,
+                              FAR struct mouse_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->exclsem);
+
+  /* Try to get the a sample... if we cannot, then wait on the semaphore
+   * that is posted when new sample data is available.
+   */
+
+  while (usbhost_sample(priv, sample) < 0)
+    {
+      /* Wait for a change in the HIDMOUSE state */
+
+      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;
+        }
+
+      /* Did the mouse become disconnected while we were waiting */
+
+      if (priv->disconnected)
+        {
+          ret = -ENODEV;
+          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->exclsem);
+
+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 HIDMOUSE for some reason, the data
+   * might be read out of order.
+   */
+
+  sched_unlock();
+  return ret;
+}
+
+/****************************************************************************
+ * Name: usbhost_cfgdesc
+ *
+ * Description:
+ *   This function implements the connect() method of struct
+ *   usbhost_class_s.  This method is a callback into the class
+ *   implementation.  It is used to provide the device's configuration
+ *   descriptor to the class so that the class may initialize properly
+ *
+ * Input Parameters:
+ *   priv - The USB host class instance.
+ *   configdesc - A pointer to a uint8_t buffer container the configuration
+ *     descriptor.
+ *   desclen - The length in bytes of the configuration descriptor.
+ *   funcaddr - The USB address of the function containing the endpoint that EP0
+ *     controls
+ *
+ * Returned Values:
+ *   On success, zero (OK) is returned. On a failure, a negated errno value is
+ *   returned indicating the nature of the failure
+ *
+ * Assumptions:
+ *   This function will *not* be called from an interrupt handler.
+ *
+ ****************************************************************************/
+
+static inline int usbhost_cfgdesc(FAR struct usbhost_state_s *priv,
+                                  FAR const uint8_t *configdesc, int desclen,
+                                  uint8_t funcaddr)
+{
+  FAR struct usb_cfgdesc_s *cfgdesc;
+  FAR struct usb_desc_s *desc;
+  FAR struct usbhost_epdesc_s epindesc;
+  int remaining;
+  uint8_t found = 0;
+  bool done = false;
+  int ret;
+
+  DEBUGASSERT(priv != NULL &&
+              configdesc != NULL &&
+              desclen >= sizeof(struct usb_cfgdesc_s));
+
+  /* Keep the compiler from complaining about uninitialized variables */
+
+  memset(&epindesc, 0, sizeof(struct usbhost_epdesc_s));
+
+  /* Verify that we were passed a configuration descriptor */
+
+  cfgdesc = (FAR struct usb_cfgdesc_s *)configdesc;
+  if (cfgdesc->type != USB_DESC_TYPE_CONFIG)
+    {
+      return -EINVAL;
+    }
+
+  /* Get the total length of the configuration descriptor (little endian).
+   * It might be a good check to get the number of interfaces here too.
+  */
+
+  remaining = (int)usbhost_getle16(cfgdesc->totallen);
+
+  /* Skip to the next entry descriptor */
+
+  configdesc += cfgdesc->len;
+  remaining  -= cfgdesc->len;
+
+  /* Loop where there are more descriptors to examine */
+
+  while (remaining >= sizeof(struct usb_desc_s) && !done)
+    {
+      /* What is the next descriptor? */
+
+      desc = (FAR struct usb_desc_s *)configdesc;
+      switch (desc->type)
+        {
+        /* Interface descriptor. We really should get the number of endpoints
+         * from this descriptor too.
+         */
+
+        case USB_DESC_TYPE_INTERFACE:
+          {
+            FAR struct usb_ifdesc_s *ifdesc = (FAR struct usb_ifdesc_s *)configdesc;
+
+            uvdbg("Interface descriptor\n");
+            DEBUGASSERT(remaining >= USB_SIZEOF_IFDESC);
+
+            /* Did we already find what we needed from a preceding interface? */
+
+            if ((found & USBHOST_ALLFOUND) == USBHOST_ALLFOUND)
+              {
+                /* Yes.. then break out of the loop and use the preceding
+                 * interface.
+                 */
+
+                done = true;
+              }
+            else
+              {
+                /* Otherwise, save the interface number and discard any
+                 * endpoints previously found
+                 */
+
+                priv->ifno = ifdesc->ifno;
+                found      = USBHOST_IFFOUND;
+              }
+          }
+          break;
+
+        /* HID descriptor */
+
+        case USBHID_DESCTYPE_HID:
+            uvdbg("HID descriptor\n");
+            break;
+
+        /* Endpoint descriptor.  We expect one or two interrupt endpoints,
+         * a required IN endpoint and an optional OUT endpoint.
+         */
+
+        case USB_DESC_TYPE_ENDPOINT:
+          {
+            FAR struct usb_epdesc_s *epdesc = (FAR struct usb_epdesc_s *)configdesc;
+
+            uvdbg("Endpoint descriptor\n");
+            DEBUGASSERT(remaining >= USB_SIZEOF_EPDESC);
+
+            /* Check for an interrupt endpoint. */
+
+            if ((epdesc->attr & USB_EP_ATTR_XFERTYPE_MASK) == USB_EP_ATTR_XFER_INT)
+              {
+                /* Yes.. it is a interrupt endpoint.  IN or OUT? */
+
+                if (USB_ISEPIN(epdesc->addr))
+                  {
+                    /* It is an interrupt IN endpoint.  There should be only
+                     * one interrupt IN endpoint.
+                     */
+
+                    if ((found & USBHOST_EPINFOUND) != 0)
+                      {
+                        /* Oops.. more than one endpoint.  We don't know what
+                         * to do with this.
+                         */
+
+                        return -EINVAL;
+                      }
+
+                    found |= USBHOST_EPINFOUND;
+
+                    /* Save the interrupt IN endpoint information */
+
+                    epindesc.addr         = epdesc->addr & USB_EP_ADDR_NUMBER_MASK;
+                    epindesc.in           = 1;
+                    epindesc.funcaddr     = funcaddr;
+                    epindesc.xfrtype      = USB_EP_ATTR_XFER_INT;
+                    epindesc.interval     = epdesc->interval;
+                    epindesc.mxpacketsize = usbhost_getle16(epdesc->mxpacketsize);
+
+                    uvdbg("Interrupt IN EP addr:%d mxpacketsize:%d\n",
+                          epindesc.addr, epindesc.mxpacketsize);
+                  }
+              }
+          }
+          break;
+
+        /* Other descriptors are just ignored for now */
+
+        default:
+          uvdbg("Other descriptor: %d\n", desc->type);
+          break;
+        }
+
+      /* What we found everything that we are going to find? */
+
+      if (found == USBHOST_ALLFOUND)
+        {
+          /* Yes.. then break out of the loop and use the preceding interface */
+
+          done = true;
+        }
+
+      /* Increment the address of the next descriptor */
+
+      configdesc += desc->len;
+      remaining  -= desc->len;
+    }
+
+  /* Sanity checking... did we find all of things that we need? */
+
+  if ((found & USBHOST_ALLFOUND) != USBHOST_ALLFOUND)
+    {
+      ulldbg("ERROR: Found IF:%s EPIN:%s\n",
+             (found & USBHOST_IFFOUND) != 0  ? "YES" : "NO",
+             (found & USBHOST_EPINFOUND) != 0 ? "YES" : "NO");
+      return -EINVAL;
+    }
+
+  /* We are good... Allocate the endpoints.  First, the required interrupt
+   * IN endpoint.
+   */
+
+  ret = DRVR_EPALLOC(priv->drvr, &epindesc, &priv->epin);
+  if (ret != OK)
+    {
+      udbg("ERROR: Failed to allocate interrupt IN endpoint\n");
+      return ret;
+    }
+
+  ullvdbg("Endpoint allocated\n");
+  return OK;
+}
+
+/****************************************************************************
+ * Name: usbhost_devinit
+ *
+ * Description:
+ *   The USB device has been successfully connected.  This completes the
+ *   initialization operations.  It is first called after the
+ *   configuration descriptor has been received.
+ *
+ *   This function is called from the connect() method.  This function always
+ *   executes on the thread of the caller of connect().
+ *
+ * Input Parameters:
+ *   priv - A reference to the class instance.
+ *
+ * Returned Values:
+ *   None
+ *
+ ****************************************************************************/
+
+static inline int usbhost_devinit(FAR struct usbhost_state_s *priv)
+{
+  char devname[DEV_NAMELEN];
+  int ret;
+
+  /* Set aside a transfer buffer for exclusive use by the mouse class driver */
+
+  ret = usbhost_tdalloc(priv);
+  if (ret != OK)
+    {
+      udbg("ERROR: Failed to allocate transfer buffer\n");
+      return ret;
+    }
+
+  /* Increment the reference count.  This will prevent usbhost_destroy() from
+   * being called asynchronously if the device is removed.
+   */
+
+  priv->crefs++;
+  DEBUGASSERT(priv->crefs == 2);
+
+  /* Start a worker task to poll the USB device.  It would be nice to used the
+   * the NuttX worker thread to do this, but this task needs to wait for events
+   * and activities on the worker thread should not involve significant waiting.
+   * Having a dedicated thread is more efficient in this sense, but requires more
+   * memory resources, primarily for the dedicated stack (CONFIG_HIDMOUSE_STACKSIZE).
+   */
+
+  uvdbg("user_start: Start poll task\n");
+
+  /* The inputs to a task started by task_create() are very awkward for this
+   * purpose.  They are really designed for command line tasks (argc/argv). So
+   * the following is kludge pass binary data when the mouse poll task
+   * is started.
+   *
+   * First, make sure we have exclusive access to g_priv (what is the likelihood
+   * of this being used?  About zero, but we protect it anyway).
+   */
+
+  usbhost_takesem(&g_exclsem);
+  g_priv = priv;
+
+#ifndef CONFIG_CUSTOM_STACK
+  priv->pollpid = task_create("mouse", CONFIG_HIDMOUSE_DEFPRIO,
+                              CONFIG_HIDMOUSE_STACKSIZE,
+                              (main_t)usbhost_mouse_poll, (FAR char * const *)NULL);
+#else
+  priv->pollpid = task_create("mouse", CONFIG_HIDMOUSE_DEFPRIO,
+                              (main_t)usbhost_mouse_poll, (FAR char * const *)NULL);
+#endif
+  if (priv->pollpid == ERROR)
+    {
+      /* Failed to started the poll thread... probably due to memory resources */
+
+      usbhost_givesem(&g_exclsem);
+      ret = -ENOMEM;
+      goto errout;
+    }
+
+  /* Now wait for the poll task to get properly initialized */
+
+  usbhost_takesem(&g_syncsem);
+  usbhost_givesem(&g_exclsem);
+
+  /* Register the driver */
+
+  uvdbg("Register driver\n");
+  usbhost_mkdevname(priv, devname);
+  ret = register_driver(devname, &g_hidmouse_fops, 0666, priv);
+
+  /* We now have to be concerned about asynchronous modification of crefs
+   * because the driver has been registered.
+   */
+
+errout:
+  usbhost_takesem(&priv->exclsem);
+  priv->crefs--;
+  usbhost_givesem(&priv->exclsem);
+  return ret;
+}
+
+/****************************************************************************
+ * Name: usbhost_getle16
+ *
+ * Description:
+ *   Get a (possibly unaligned) 16-bit little endian value.
+ *
+ * Input Parameters:
+ *   val - A pointer to the first byte of the little endian value.
+ *
+ * Returned Values:
+ *   A uint16_t representing the whole 16-bit integer value
+ *
+ ****************************************************************************/
+
+static inline uint16_t usbhost_getle16(const uint8_t *val)
+{
+  return (uint16_t)val[1] << 8 | (uint16_t)val[0];
+}
+
+/****************************************************************************
+ * Name: usbhost_putle16
+ *
+ * Description:
+ *   Put a (possibly unaligned) 16-bit little endian value.
+ *
+ * Input Parameters:
+ *   dest - A pointer to the first byte to save the little endian value.
+ *   val - The 16-bit value to be saved.
+ *
+ * Returned Values:
+ *   None
+ *
+ ****************************************************************************/
+
+static void usbhost_putle16(uint8_t *dest, uint16_t val)
+{
+  dest[0] = val & 0xff; /* Little endian means LS byte first in byte stream */
+  dest[1] = val >> 8;
+}
+
+/****************************************************************************
+ * Name: usbhost_getle32
+ *
+ * Description:
+ *   Get a (possibly unaligned) 32-bit little endian value.
+ *
+ * Input Parameters:
+ *   dest - A pointer to the first byte to save the big endian value.
+ *   val - The 32-bit value to be saved.
+ *
+ * Returned Values:
+ *   None
+ *
+ ****************************************************************************/
+
+static inline uint32_t usbhost_getle32(const uint8_t *val)
+{
+ /* Little endian means LS halfword first in byte stream */
+
+  return (uint32_t)usbhost_getle16(&val[2]) << 16 | (uint32_t)usbhost_getle16(val);
+}
+
+/****************************************************************************
+ * Name: usbhost_putle32
+ *
+ * Description:
+ *   Put a (possibly unaligned) 32-bit little endian value.
+ *
+ * Input Parameters:
+ *   dest - A pointer to the first byte to save the little endian value.
+ *   val - The 32-bit value to be saved.
+ *
+ * Returned Values:
+ *   None
+ *
+ ****************************************************************************/
+
+#if 0 /* Not used */
+static void usbhost_putle32(uint8_t *dest, uint32_t val)
+{
+  /* Little endian means LS halfword first in byte stream */
+
+  usbhost_putle16(dest, (uint16_t)(val & 0xffff));
+  usbhost_putle16(dest+2, (uint16_t)(val >> 16));
+}
+#endif
+
+/****************************************************************************
+ * Name: usbhost_tdalloc
+ *
+ * Description:
+ *   Allocate transfer buffer memory.
+ *
+ * Input Parameters:
+ *   priv - A reference to the class instance.
+ *
+ * Returned Values:
+ *   On success, zero (OK) is returned.  On failure, an negated errno value
+ *   is returned to indicate the nature of the failure.
+ *
+ ****************************************************************************/
+
+static inline int usbhost_tdalloc(FAR struct usbhost_state_s *priv)
+{
+  DEBUGASSERT(priv && priv->tbuffer == NULL);
+  return DRVR_ALLOC(priv->drvr, &priv->tbuffer, &priv->tbuflen);
+}
+
+/****************************************************************************
+ * Name: usbhost_tdfree
+ *
+ * Description:
+ *   Free transfer buffer memory.
+ *
+ * Input Parameters:
+ *   priv - A reference to the class instance.
+ *
+ * Returned Values:
+ *   On success, zero (OK) is returned.  On failure, an negated errno value
+ *   is returned to indicate the nature of the failure.
+ *
+ ****************************************************************************/
+
+static inline int usbhost_tdfree(FAR struct usbhost_state_s *priv)
+{
+  int result = OK;
+  DEBUGASSERT(priv);
+
+  if (priv->tbuffer)
+    {
+      DEBUGASSERT(priv->drvr);
+      result         = DRVR_FREE(priv->drvr, priv->tbuffer);
+      priv->tbuffer = NULL;
+      priv->tbuflen = 0;
+    }
+
+  return result;
+}
+
+/****************************************************************************
+ * struct usbhost_registry_s methods
+ ****************************************************************************/
+
+/****************************************************************************
+ * Name: usbhost_create
+ *
+ * Description:
+ *   This function implements the create() method of struct usbhost_registry_s.
+ *   The create() method is a callback into the class implementation.  It is
+ *   used to (1) create a new instance of the USB host class state and to (2)
+ *   bind a USB host driver "session" to the class instance.  Use of this
+ *   create() method will support environments where there may be multiple
+ *   USB ports and multiple USB devices simultaneously connected.
+ *
+ * Input Parameters:
+ *   drvr - An instance of struct usbhost_driver_s that the class
+ *     implementation will "bind" to its state structure and will
+ *     subsequently use to communicate with the USB host driver.
+ *   id - In the case where the device supports multiple base classes,
+ *     subclasses, or protocols, this specifies which to configure for.
+ *
+ * Returned Values:
+ *   On success, this function will return a non-NULL instance of struct
+ *   usbhost_class_s that can be used by the USB host driver to communicate
+ *   with the USB host class.  NULL is returned on failure; this function
+ *   will fail only if the drvr input parameter is NULL or if there are
+ *   insufficient resources to create another USB host class instance.
+ *
+ ****************************************************************************/
+
+static FAR struct usbhost_class_s *
+  usbhost_create(FAR struct usbhost_driver_s *drvr,
+                 FAR const struct usbhost_id_s *id)
+{
+  FAR struct usbhost_state_s *priv;
+
+  /* Allocate a USB host class instance */
+
+  priv = usbhost_allocclass();
+  if (priv)
+    {
+      /* Initialize the allocated storage class instance */
+
+      memset(priv, 0, sizeof(struct usbhost_state_s));
+
+      /* Assign a device number to this class instance */
+
+      if (usbhost_allocdevno(priv) == OK)
+        {
+         /* Initialize class method function pointers */
+
+          priv->class.connect      = usbhost_connect;
+          priv->class.disconnected = usbhost_disconnected;
+
+          /* The initial reference count is 1... One reference is held by
+           * the driver.
+           */
+
+          priv->crefs              = 1;
+
+          /* Initialize semaphores */
+
+          sem_init(&priv->exclsem, 0, 1);
+          sem_init(&priv->waitsem, 0, 0);
+
+          /* Bind the driver to the storage class instance */
+
+          priv->drvr               = drvr;
+
+          /* Return the instance of the USB mouse class driver */
+
+          return &priv->class;
+        }
+    }
+
+  /* An error occurred. Free the allocation and return NULL on all failures */
+
+  if (priv)
+    {
+      usbhost_freeclass(priv);
+    }
+
+  return NULL;
+}
+
+/****************************************************************************
+ * struct usbhost_class_s methods
+ ****************************************************************************/
+/****************************************************************************
+ * Name: usbhost_connect
+ *
+ * Description:
+ *   This function implements the connect() method of struct
+ *   usbhost_class_s.  This method is a callback into the class
+ *   implementation.  It is used to provide the device's configuration
+ *   descriptor to the class so that the class may initialize properly
+ *
+ * Input Parameters:
+ *   class - The USB host class entry previously obtained from a call to create().
+ *   configdesc - A pointer to a uint8_t buffer container the configuration
+ *     descriptor.
+ *   desclen - The length in bytes of the configuration descriptor.
+ *   funcaddr - The USB address of the function containing the endpoint that EP0
+ *     controls
+ *
+ * Returned Values:
+ *   On success, zero (OK) is returned. On a failure, a negated errno value is
+ *   returned indicating the nature of the failure
+ *
+ *   NOTE that the class instance remains valid upon return with a failure.  It is
+ *   the responsibility of the higher level enumeration logic to call
+ *   CLASS_DISCONNECTED to free up the class driver resources.
+ *
+ * Assumptions:
+ *   - This function will *not* be called from an interrupt handler.
+ *   - If this function returns an error, the USB host controller driver
+ *     must call to DISCONNECTED method to recover from the error
+ *
+ ****************************************************************************/
+
+static int usbhost_connect(FAR struct usbhost_class_s *class,
+                           FAR const uint8_t *configdesc, int desclen,
+                           uint8_t funcaddr)
+{
+  FAR struct usbhost_state_s *priv = (FAR struct usbhost_state_s *)class;
+  int ret;
+
+  DEBUGASSERT(priv != NULL &&
+              configdesc != NULL &&
+              desclen >= sizeof(struct usb_cfgdesc_s));
+
+  /* Parse the configuration descriptor to get the endpoints */
+
+  ret = usbhost_cfgdesc(priv, configdesc, desclen, funcaddr);
+  if (ret != OK)
+    {
+      udbg("usbhost_cfgdesc() failed: %d\n", ret);
+    }
+  else
+    {
+      /* Now configure the device and register the NuttX driver */
+
+      ret = usbhost_devinit(priv);
+      if (ret != OK)
+        {
+          udbg("usbhost_devinit() failed: %d\n", ret);
+        }
+    }
+
+  /* ERROR handling:  Do nothing. If we return and error during connection,
+   * the driver is required to call the DISCONNECT method.  Possibilities:
+   *
+   * - Failure occurred before the mouse poll task was started successfully.
+   *   In this case, the disconnection will have to be handled on the worker
+   *   task.
+   * - Failure occurred after the mouse poll task was started successfully.  In
+   *   this case, the disconnection can be performed on the mouse poll thread.
+   */
+
+  return ret;
+}
+
+/****************************************************************************
+ * Name: usbhost_disconnected
+ *
+ * Description:
+ *   This function implements the disconnected() method of struct
+ *   usbhost_class_s.  This method is a callback into the class
+ *   implementation.  It is used to inform the class that the USB device has
+ *   been disconnected.
+ *
+ * Input Parameters:
+ *   class - The USB host class entry previously obtained from a call to
+ *     create().
+ *
+ * Returned Values:
+ *   On success, zero (OK) is returned. On a failure, a negated errno value
+ *   is returned indicating the nature of the failure
+ *
+ * Assumptions:
+ *   This function may be called from an interrupt handler.
+ *
+ ****************************************************************************/
+
+static int usbhost_disconnected(struct usbhost_class_s *class)
+{
+  FAR struct usbhost_state_s *priv = (FAR struct usbhost_state_s *)class;
+
+  DEBUGASSERT(priv != NULL);
+
+  /* Set an indication to any users of the mouse device that the device
+   * is no longer available.
+   */
+
+  priv->disconnected = true;
+  ullvdbg("Disconnected\n");
+
+  /* Is there a thread waiting for mouse data that will never come? */
+
+  if (priv->waiting)
+    {
+      /* Yes.. wake it up */
+
+      usbhost_givesem(&priv->waitsem);
+      priv->waiting = false;
+    }
+
+  /* Possibilities:
+   *
+   * - Failure occurred before the mouse poll task was started successfully.
+   *   In this case, the disconnection will have to be handled on the worker
+   *   task.
+   * - Failure occurred after the mouse poll task was started successfully.  In
+   *   this case, the disconnection can be performed on the mouse poll thread.
+   */
+
+  if (priv->polling)
+    {
+      /* The polling task is still alive. Signal the mouse polling task.
+       * When that task wakes up, it will decrement the reference count and,
+       * perhaps, destroy the class instance.  Then it will exit.
+       */
+
+      (void)kill(priv->pollpid, SIGALRM);
+    }
+  else
+    {
+      /* In the case where the failure occurs before the polling task was
+       * started.  Now what?  We are probably executing from an interrupt
+       * handler here.  We will use the worker thread.  This is kind of
+       * wasteful and begs for a re-design.
+       */
+
+      DEBUGASSERT(priv->work.worker == NULL);
+      (void)work_queue(HPWORK, &priv->work, usbhost_destroy, priv, 0);
+    }
+
+  return OK;
+}
+
+/****************************************************************************
+ * Character driver methods
+ ****************************************************************************/
+/****************************************************************************
+ * Name: usbhost_open
+ *
+ * Description:
+ *   Standard character driver open method.
+ *
+ ****************************************************************************/
+
+static int usbhost_open(FAR struct file *filep)
+{
+  FAR struct inode           *inode;
+  FAR struct usbhost_state_s *priv;
+  irqstate_t flags;
+  int ret;
+
+  uvdbg("Entry\n");
+  DEBUGASSERT(filep && filep->f_inode);
+  inode = filep->f_inode;
+  priv  = inode->i_private;
+
+  /* Make sure that we have exclusive access to the private data structure */
+
+  DEBUGASSERT(priv && priv->crefs > 0 && priv->crefs < USBHOST_MAX_CREFS);
+  usbhost_takesem(&priv->exclsem);
+
+  /* Check if the mouse device is still connected.  We need to disable
+   * interrupts momentarily to assure that there are no asynchronous disconnect
+   * events.
+   */
+
+  flags = irqsave();
+  if (priv->disconnected)
+    {
+      /* No... the driver is no longer bound to the class.  That means that
+       * the USB storage device is no longer connected.  Refuse any further
+       * attempts to open the driver.
+       */
+
+      ret = -ENODEV;
+    }
+  else
+    {
+      /* Was the driver previously open?  We need to perform special
+       * initialization on the first time that the driver is opened.
+       */
+
+      if (!priv->open)
+        {
+          /* Set the thresholding values so that the first button press
+           * will be reported.
+           */
+
+          priv->xlast = INVALID_POSITION_B16;
+          priv->ylast = INVALID_POSITION_B16;
+
+          /* Set the reported position to the center of the range */
+
+          priv->xpos = (CONFIG_HIDMOUSE_XMAX >> 1);
+          priv->ypos = (CONFIG_HIDMOUSE_YMAX >> 1);
+        }
+
+      /* Otherwise, just increment the reference count on the driver */
+
+      priv->crefs++;
+      priv->open = true;
+      ret        = OK;
+    }
+
+  irqrestore(flags);
+
+  usbhost_givesem(&priv->exclsem);
+  return ret;
+}
+
+/****************************************************************************
+ * Name: usbhost_close
+ *
+ * Description:
+ *   Standard character driver close method.
+ *
+ ****************************************************************************/
+
+static int usbhost_close(FAR struct file *filep)
+{
+  FAR struct inode           *inode;
+  FAR struct usbhost_state_s *priv;
+
+  uvdbg("Entry\n");
+  DEBUGASSERT(filep && filep->f_inode);
+  inode = filep->f_inode;
+  priv  = inode->i_private;
+
+  /* Decrement the reference count on the driver */
+
+  DEBUGASSERT(priv->crefs > 1);
+  usbhost_takesem(&priv->exclsem);
+  priv->crefs--;
+
+  /* Is this the last reference (other than the one held by the USB host
+   * controller driver)
+   */
+
+  if (priv->crefs <= 1)
+    {
+      irqstate_t flags;
+
+      /* Yes.. then the driver is no longer open */
+
+      priv->open = false;
+
+      /* We need to disable interrupts momentarily to assure that there are
+       * no asynchronous disconnect events.
+       */
+
+      flags = irqsave();
+
+      /* Check if the USB mouse device is still connected.  If the device is
+       * no longer connected, then unregister the driver and free the driver
+       * class instance.
+       */
+
+      if (priv->disconnected)
+        {
+          /* Destroy the class instance (we can't use priv after this; we can't
+           * 'give' the semaphore)
+           */
+
+          usbhost_destroy(priv);
+          irqrestore(flags);
+          return OK;
+        }
+
+      irqrestore(flags);
+    }
+
+  usbhost_givesem(&priv->exclsem);
+  return OK;
+}
+
+/****************************************************************************
+ * Name: usbhost_read
+ *
+ * Description:
+ *   Standard character driver read method.
+ *
+ ****************************************************************************/
+
+static ssize_t usbhost_read(FAR struct file *filep, FAR char *buffer, size_t len)
+{
+  FAR struct inode           *inode;
+  FAR struct usbhost_state_s *priv;
+  FAR struct touch_sample_s  *report;
+  struct mouse_sample_s       sample;
+  int                         ret;
+
+  uvdbg("Entry\n");
+  DEBUGASSERT(filep && filep->f_inode && buffer);
+  inode = filep->f_inode;
+  priv  = inode->i_private;
+
+  /* Make sure that we have exclusive access to the private data structure */
+
+  DEBUGASSERT(priv && priv->crefs > 0 && priv->crefs < USBHOST_MAX_CREFS);
+  usbhost_takesem(&priv->exclsem);
+
+  /* Check if the mouse is still connected.  We need to disable interrupts
+   * momentarily to assure that there are no asynchronous disconnect events.
+   */
+
+  if (priv->disconnected)
+    {
+      /* No... the driver is no longer bound to the class.  That means that
+       * the USB mouse is no longer connected.  Refuse any further attempts
+       * to access the driver.
+       */
+
+      ret = -ENODEV;
+      goto errout;
+    }
+
+  /* Try to read sample data. */
+
+  ret = usbhost_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.
+       */
+
+      if (filep->f_oflags & O_NONBLOCK)
+        {
+          /* Yes.. then return a failure */
+
+          ret = -EAGAIN;
+          goto errout;
+        }
+
+      /* Wait for sample data */
+
+      ret = usbhost_waitsample(priv, &sample);
+      if (ret < 0)
+        {
+          /* We might have been awakened by a signal */
+
+          idbg("usbhost_waitsample: %d\n", ret);
+          goto errout;
+        }
+    }
+
+  /* We now have sampled HIDMOUSE 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.event == BUTTON_RELEASED)
+    {
+      /* But was released.  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.event == BUTTON_PRESSED)
+    {
+      /* First event */
+
+      report->point[0].flags  = TOUCH_DOWN | TOUCH_ID_VALID | TOUCH_POS_VALID;
+    }
+  else /* if (sample->event == BUTTON_MOVE) */
+    {
+      /* Movement of the same event */
+
+      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:
+  usbhost_givesem(&priv->exclsem);
+  ivdbg("Returning: %d\n", ret);
+  return (ssize_t)ret;
+}
+
+/****************************************************************************
+ * Name: usbhost_write
+ *
+ * Description:
+ *   Standard character driver write method.
+ *
+ ****************************************************************************/
+
+static ssize_t usbhost_write(FAR struct file *filep, FAR const char *buffer,
+                             size_t len)
+{
+  /* We won't try to write to the mouse */
+
+  return -ENOSYS;
+}
+
+/****************************************************************************
+ * Name: usbhost_poll
+ *
+ * Description:
+ *   Standard character driver poll method.
+ *
+ ****************************************************************************/
+
+#ifndef CONFIG_DISABLE_POLL
+static int usbhost_poll(FAR struct file *filep, FAR struct pollfd *fds,
+                        bool setup)
+{
+  FAR struct inode           *inode;
+  FAR struct usbhost_state_s *priv;
+  int                         ret = OK;
+  int                         i;
+
+  uvdbg("Entry\n");
+  DEBUGASSERT(filep && filep->f_inode && fds);
+  inode = filep->f_inode;
+  priv  = inode->i_private;
+
+  /* Make sure that we have exclusive access to the private data structure */
+
+  DEBUGASSERT(priv);
+  usbhost_takesem(&priv->exclsem);
+
+  /* Check if the mouse is still connected.  We need to disable interrupts
+   * momentarily to assure that there are no asynchronous disconnect events.
+   */
+
+  if (priv->disconnected)
+    {
+      /* No... the driver is no longer bound to the class.  That means that
+       * the USB mouse is no longer connected.  Refuse any further attempts
+       * to access the driver.
+       */
+
+      ret = -ENODEV;
+    }
+  else if (setup)
+    {
+      /* This is a request to set up the poll.  Find an available slot for
+       * the poll structure reference
+       */
+
+      for (i = 0; i < CONFIG_HIDMOUSE_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_HIDMOUSE_NPOLLWAITERS)
+        {
+          fds->priv    = NULL;
+          ret          = -EBUSY;
+          goto errout;
+        }
+
+      /* Should we immediately notify on any of the requested events? Notify
+       * the POLLIN event if there is buffered mouse data.
+       */
+
+      if (priv->valid)
+        {
+          usbhost_pollnotify(priv);
+        }
+    }
+  else
+    {
+      /* This is a request to tear down the poll. */
+
+      struct pollfd **slot = (struct pollfd **)fds->priv;
+      DEBUGASSERT(slot);
+
+      /* Remove all memory of the poll setup */
+
+      *slot     = NULL;
+      fds->priv = NULL;
+    }
+
+errout:
+  sem_post(&priv->exclsem);
+  return ret;
+}
+#endif
+
+/****************************************************************************
+ * Public Functions
+ ****************************************************************************/
+
+/****************************************************************************
+ * Name: usbhost_mouse_init
+ *
+ * Description:
+ *   Initialize the USB storage HID mouse class driver.  This function
+ *   should be called be platform-specific code in order to initialize and
+ *   register support for the USB host HID mouse class device.
+ *
+ * Input Parameters:
+ *   None
+ *
+ * Returned Values:
+ *   On success this function will return zero (OK);  A negated errno value
+ *   will be returned on failure.
+ *
+ ****************************************************************************/
+
+int usbhost_mouse_init(void)
+{
+  /* Perform any one-time initialization of the class implementation */
+
+  sem_init(&g_exclsem, 0, 1);
+  sem_init(&g_syncsem, 0, 0);
+
+  /* Advertise our availability to support (certain) mouse devices */
+
+  return usbhost_registerclass(&g_hidmouse);
+}
+
+#endif /* CONFIG_USBHOST)&& !CONFIG_USBHOST_INT_DISABLE && CONFIG_NFILE_DESCRIPTORS */