nuttx/drivers/usbhost/usbhost_hidkbd.c

/****************************************************************************
 * drivers/usbhost/usbhost_hidkbd.c
 *
 *   Copyright (C) 2011 Gregory Nutt. All rights reserved.
 *   Author: Gregory Nutt <spudmonkey@racsa.co.cr>
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 *
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in
 *    the documentation and/or other materials provided with the
 *    distribution.
 * 3. Neither the name NuttX nor the names of its contributors may be
 *    used to endorse or promote products derived from this software
 *    without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
 * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
 * COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
 * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
 * OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
 * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
 * ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
 * POSSIBILITY OF SUCH DAMAGE.
 *
 ****************************************************************************/

/****************************************************************************
 * Included Files
 ****************************************************************************/

#include <nuttx/config.h>

#include <sys/types.h>
#include <stdbool.h>
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <string.h>
#include <poll.h>
#include <semaphore.h>
#include <time.h>
#include <assert.h>
#include <errno.h>
#include <debug.h>

#include <nuttx/fs.h>
#include <nuttx/arch.h>

#include <nuttx/usb/usb.h>
#include <nuttx/usb/usbhost.h>
#include <nuttx/usb/hid.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 keyboard will be polled in units of
 * of microseconds.  The default is 100MS.
 */

#ifndef CONFIG_HIDKBD_POLLUSEC
#  define CONFIG_HIDKBD_POLLUSEC (100*1000)
#endif

/* Signals must not be disabled as they are needed by usleep */

/* Provide some default values for other configuration settings */

#ifndef CONFIG_HIDKBD_DEFPRIO
#  define CONFIG_HIDKBD_DEFPRIO 50
#endif
#ifndef CONFIG_HIDKBD_STACKSIZE
#  define CONFIG_HIDKBD_STACKSIZE 1024
#endif

/* Driver support ***********************************************************/
/* This format is used to construct the /dev/kbd[n] device driver path.  It
 * defined here so that it will be used consistently in all places.
 */

#define DEV_FORMAT          "/dev/kbd%c"
#define DEV_NAMELEN         11

/* 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_EPOUTFOUND  0x04 /* Optional interrupt OUT EP descriptor found */
#define USBHOST_RQDFOUND    (USBHOST_IFFOUND|USBHOST_EPINFOUND)

#define USBHOST_MAX_CREFS   0x7fff

/****************************************************************************
 * Private Types
 ****************************************************************************/

/* This structure contains the internal, private state of the USB host
 * keyboard 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 keyboard class driver */
  
  char                    devchar;      /* Character identifying the /dev/kbd[n] device */
  volatile bool           disconnected; /* TRUE: Device has been disconnected */
  volatile bool           polling;      /* TRUE: Poll thread is running */
  int16_t                 crefs;        /* Reference count on the driver instance */
  sem_t                   exclsem;      /* Used to maintain mutual exclusive access */
  FAR uint8_t            *tbuffer;      /* The allocated transfer buffer */
  size_t                  tbuflen;      /* Size of the allocated transfer buffer */
  pid_t                   pollpid;      /* PID of the poll task */

  /* Endpoints:
   * EP0 (Control):
   * - Receiving and responding to requests for USB control and class data.
   * - IN data when polled by the HID class driver (Get_Report)
   * - OUT data from the host.
   * EP Interrupt IN:
   * - Receiving asynchronous (unrequested) IN data from the device.
   * EP Interrrupt OUT (optional):
   * - Transmitting low latency OUT data to the device.
   * - If not present, EP0 used.
   */

  usbhost_ep_t            epin;         /* Interrupt IN endpoint */
  usbhost_ep_t            epout;        /* Optional interrupt OUT endpoint */
};

/****************************************************************************
 * Private Function Prototypes
 ****************************************************************************/

/* Semaphores */

static void usbhost_takesem(sem_t *sem);
#define usbhost_givesem(s) sem_post(s);

/* 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);

/* Keyboard polling thread */

static void usbhost_destroy(FAR struct usbhost_state_s *priv);
static int usbhost_kbdpoll(int argc, char *argv[]);

/* 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);
static void usbhost_putle32(uint8_t *dest, uint32_t val);

/* 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 keyboard 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 informatino that will  be 
 * used to associate the USB host keyboard class driver to a connected USB
 * device.
 */

static const const struct usbhost_id_s g_id =
{
  USB_CLASS_HID,            /* base     */
  USBHID_SUBCLASS_BOOTIF,   /* subclass */
  USBHID_PROTOCOL_KEYBOARD, /* proto    */
  0,                        /* vid      */
  0                         /* pid      */
};

/* This is the USB host storage class's registry entry */

static struct usbhost_registry_s g_skeleton =
{
  NULL,                    /* flink     */
  usbhost_create,          /* create    */
  1,                       /* nids      */
  &g_id                    /* id[]      */
};

static const struct file_operations usbhost_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/kbda-z. */

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 occr here is if the wait was
       * awakened by a signal.
       */

      ASSERT(errno == EINTR);
    }
}

/****************************************************************************
 * 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 *)malloc(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 (calling sched_free() in case we are executing
   * from an interrupt handler.
   */

  uvdbg("Freeing: %p\n", class);;
  free(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->devchar = 'a' + devno;
          irqrestore(flags);
          return OK;
        }
    }

  irqrestore(flags);
  return -EMFILE;
}

static void usbhost_freedevno(FAR struct usbhost_state_s *priv)
{
  int devno = 'a' - priv->devchar;

  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->devchar);
}

/****************************************************************************
 * Name: usbhost_destroy
 *
 * Description:
 *   The USB device has been disconnected and the refernce 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 struct usbhost_state_s *priv)
{
  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);
    }

  if (priv->epout)
    {
      DRVR_EPFREE(priv->drvr, priv->epout);
    }

  /* Free any transfer buffers */

  usbhost_tdfree(priv);

  /* Destroy the semaphores */

  sem_destroy(&priv->exclsem);

  /* 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_dumprpt
 *
 * Description:
 *   Dump the interesting context of the keyboard report that we just
 *   received.
 *
 * Input Parameters:
 *   arg - A reference to the class instance to be destroyed.
 *
 * Returned Values:
 *   None
 *
 ****************************************************************************/

#if defined(CONFIG_DEBUG_USB) && defined(CONFIG_DEBUG_VERBOSE)
static inline void usbhost_dumprpt(uint8_t *buffer)
{
  struct usbhid_kbdreport_s *rpt = (struct usbhid_kbdreport_s *)buffer;
  int i;
  for (i = 0; i < 6; i++)
    {
      if (rpt->key[i])
        {
          uvdbg("Key %d: %08x modifier: %08x\n", rpt->key[i], rpt->modifier);
        }
    }
}
#else
#  define usbhost_dumprpt(buffer)
#endif

/****************************************************************************
 * Name: usbhost_kbdpoll
 *
 * Description:
 *   Periodically check for new keyboard data.
 *
 * Input Parameters:
 *   arg - A reference to the class instance to be destroyed.
 *
 * Returned Values:
 *   None
 *
 ****************************************************************************/

static int usbhost_kbdpoll(int argc, char *argv[])
{
  FAR struct usbhost_state_s *priv;
  FAR struct usb_ctrlreq_s   *ctrlreq;
#ifdef CONFIG_DEBUG_USB
  static unsigned int         npolls = 0;
#endif
  static unsigned int         nerrors;
  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 10000001
       *   bRequest      GET_DESCRIPTOR (0x06)
       *   wValue        Descriptor Type and Descriptor 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_RECIPIENT_INTERFACE;
      ctrlreq->req  = USB_REQ_GETDESCRIPTOR;
      usbhost_putle16(ctrlreq->value, (USBHID_DESCTYPE_REPORT << 8));
      usbhost_putle16(ctrlreq->index, 0);
      usbhost_putle16(ctrlreq->len, 8);

      /* Send the report */

      ret = DRVR_CTRLIN(priv->drvr, ctrlreq, priv->tbuffer);
      usbhost_givesem(&priv->exclsem);

      if (ret != OK)
        {
          nerrors++;
          udbg("ERROR: GETDESCRIPTOR/REPORT, DRVR_CTRLIN returned: %d/%d\n",
               ret, nerrors);

          if (nerrors > 200)
            {
              udbg("Too man errors... aborting: %d\n", nerrors);
              break;
            }
        }
      else
        {
          /* If debug is enabled, then dump the interesting poarts of the
           * report that we just received.
           */

          usbhost_dumprpt(priv->tbuffer);

          /* Add the newly recevied keystrokes to our internal buffer */
#warning "Missing logic"
        }

      /* If USB debug is on, then provide some periodic indication that
       * polling is still happening.
       */

#ifdef CONFIG_DEBUG_USB
      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_HIDKBD_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("Keyboard 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_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 descripor.
 *   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;
  FAR struct usbhost_epdesc_s epoutdesc;
  int remaining;
  uint8_t found = 0;
  int ret;

  DEBUGASSERT(priv != NULL && 
              configdesc != NULL &&
              desclen >= sizeof(struct usb_cfgdesc_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 dscriptors to examine */

  while (remaining >= sizeof(struct usb_desc_s))
    {
      /* 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:
          {
            uvdbg("Interface descriptor\n");
            DEBUGASSERT(remaining >= USB_SIZEOF_IFDESC);
            if ((found & USBHOST_IFFOUND) != 0)
              {
                /* Oops.. more than one interface.  We don't know what to do with this. */

                return -ENOSYS;
              }
            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_ISEPOUT(epdesc->addr))
                  {
                    /* It is an interrupt OUT endpoint.  There not be more than one
                     * interrupt OUT endpoint.
                     */

                    if ((found & USBHOST_EPOUTFOUND) != 0)
                      {
                        /* Oops.. more than one endpoint.  We don't know what to do with this. */

                        return -EINVAL;
                      }
                    found |= USBHOST_EPOUTFOUND;

                    /* Save the interrupt OUT endpoint information */

                    epoutdesc.addr         = epdesc->addr & USB_EP_ADDR_NUMBER_MASK;
                    epoutdesc.in           = false;
                    epoutdesc.funcaddr     = funcaddr;
                    epoutdesc.xfrtype      = USB_EP_ATTR_XFER_INT;
                    epoutdesc.interval     = epdesc->interval;
                    epoutdesc.mxpacketsize = usbhost_getle16(epdesc->mxpacketsize);
                    uvdbg("Interrupt OUT EP addr:%d mxpacketsize:%d\n",
                          epoutdesc.addr, epoutdesc.mxpacketsize);
                  }
                else
                  {
                    /* It is an interrupt IN endpoint.  There should be only
                     * one interrupt IN endpoint.
                     */

                    if ((found & USBHOST_EPINFOUND) != 0)
                      {
                        /* Oops.. more than one endpint.  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;
        }

      /* 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_RQDFOUND) != USBHOST_RQDFOUND)
    {
      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;
    }

  /* Then the optional interrupt OUT endpoint */

  ullvdbg("Found EPOOUT:%s\n",
         (found & USBHOST_EPOUTFOUND) != 0 ? "YES" : "NO");

  if ((found & USBHOST_EPOUTFOUND) != 0)
    {
      ret = DRVR_EPALLOC(priv->drvr, &epoutdesc, &priv->epout);
      if (ret != OK)
        {
          udbg("ERROR: Failed to allocate interrupt OUT endpoint\n");
          (void)DRVR_EPFREE(priv->drvr, priv->epin);
          return ret;
        }
    }

  ullvdbg("Endpoints 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 keyboard 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_HIDKBD_STACKSIZE).
   */

  uvdbg("user_start: Start poll task\n");

  /* The inputs to a task started by task_create() are very awkard for this
   * purpose.  They are really designed for command line tasks (argc/argv). So
   * the following is kludge pass binary data when the keyboard 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("usbhost", CONFIG_HIDKBD_DEFPRIO,
                              CONFIG_HIDKBD_STACKSIZE,
                              (main_t)usbhost_kbdpoll, (const char **)NULL);
#else
  priv->pollpid = task_create("usbhost", CONFIG_HIDKBD_DEFPRIO,
                              (main_t)hidkbd_waiter, (const char **)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, &usbhost_fops, 0666, NULL);

  /* We now have to be concerned about asynchronous modification of crefs
   * because the driver has been registerd.
   */

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
 *
 ****************************************************************************/

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));
}

/****************************************************************************
 * Name: usbhost_tdalloc
 *
 * Description:
 *   Allocate transfer buffer memory.
 *
 * Input Parameters:
 *   priv - A reference to the class instance.
 *
 * Returned Values:
 *   On sucess, 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 sucess, 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 semphores (this works okay in the interrupt context) */

          sem_init(&priv->exclsem, 0, 1);

          /* Bind the driver to the storage class instance */

          priv->drvr               = drvr;

          /* Return the instance of the USB keyboard 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 descripor.
 *   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 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);
        }
    }
 
  /* Disconnect on any errors detected during initialization. */

  if (ret != OK)
    {
      priv->disconnected = true;

      /* Is the polling task still running?  If so, then ask it politely to
       * stop and release its reference count.
       */
 
      while (priv->polling)
        {
          (void)kill(priv->pollpid, SIGALRM);
          usleep(500*1000);
        }

      /* The following operations when crefs == 1 are safe because we know
       * that there is no outstanding open references to the driver.
       */

      if (priv->crefs <= 1)
        {
          /* Destroy the class instance */

          usbhost_destroy(priv);
        }
    }

  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 keyboard device that the device
   * is no longer available.
   */

  priv->disconnected = true;
  ullvdbg("Disconnected\n");

  /* Signal the keyboard polling task.  When that task wakes up, it will
   * decrement the reference count and, perhaps, destroy the class instance.
   */

  (void)kill(priv->pollpid, SIGALRM);
  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->crefs > 0 && priv->crefs < USBHOST_MAX_CREFS);
  usbhost_takesem(&priv->exclsem);

  /* Check if the keyboard 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
    {
      /* Otherwise, just increment the reference count on the driver */

      priv->crefs++;
      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;
  irqstate_t flags;

  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--;

  /* Release the semaphore.  The following operations when crefs == 1 are
   * safe because we know that there is no outstanding open references to
   * the driver.
   */

  usbhost_givesem(&priv->exclsem);

  /* We need to disable interrupts momentarily to assure that there are
   * no asynchronous disconnect events.
   */

  flags = irqsave();

  /* Check if the USB keyboard device is still connected.  If the device is
   * not connected and the reference count just decremented to one, then
   * unregister then free the driver class instance.
   */

  if (priv->crefs <= 1 && priv->disconnected)
    {
      /* Destroy the class instance */

      usbhost_destroy(priv);
    }

  irqrestore(flags);
  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;
  irqstate_t flags;
  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 keyboard 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 keybaord is no longer connected.  Refuse any further attempts
       * to access the driver.
       */

      ret = -ENODEV;
    }
  else
    {
      /* Read data from our internal buffer of received characters */
#warning "Missing logic"
    }
  irqrestore(flags);

  usbhost_givesem(&priv->exclsem);
  return 0; /* Return EOF for now */
}

/****************************************************************************
 * 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 keyboard */

  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)
{
  if (setup)
    {
      fds->revents |= (fds->events & (POLLIN|POLLOUT));
      if (fds->revents != 0)
        {
          sem_post(fds->sem);
        }
    }
  return OK;
}
#endif

/****************************************************************************
 * Public Functions
 ****************************************************************************/

/****************************************************************************
 * Name: usbhost_kbdinit
 *
 * Description:
 *   Initialize the USB storage HID keyboard class driver.  This function
 *   should be called be platform-specific code in order to initialize and
 *   register support for the USB host HID keyboard 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_kbdinit(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) devices */

  return usbhost_registerclass(&g_skeleton);
}

#endif /* CONFIG_USBHOST)&& !CONFIG_USBHOST_INT_DISABLE && CONFIG_NFILE_DESCRIPTORS */