Separate enumeration logic

git-svn-id: svn://svn.code.sf.net/p/nuttx/code/trunk@3219 42af7a65-404d-4744-a932-0658087f49c3

4 files changed, 637 insertions, 360 deletions

diff --git a/nuttx/arch/arm/src/lpc17xx/lpc17_usbhost.c b/nuttx/arch/arm/src/lpc17xx/lpc17_usbhost.c
index f62ff43e7..a2678032f 100755
--- a/nuttx/arch/arm/src/lpc17xx/lpc17_usbhost.c
+++ b/nuttx/arch/arm/src/lpc17xx/lpc17_usbhost.c
@@ -255,6 +255,8 @@ static int lpc17_usbinterrupt(int irq, FAR void *context);
 
 static int lpc17_wait(FAR struct usbhost_driver_s *drvr, bool connected);
 static int lpc17_enumerate(FAR struct usbhost_driver_s *drvr);
+static int lpc17_ep0configure(FAR struct usbhost_driver_s *drvr, uint8_t funcno,
+                              uint16_t maxpacketsize);
 static int lpc17_alloc(FAR struct usbhost_driver_s *drvr,
                          FAR uint8_t **buffer, FAR size_t *maxlen);
 static int lpc17_free(FAR struct usbhost_driver_s *drvr, FAR uint8_t *buffer);
@@ -286,18 +288,19 @@ static void lpc17_hccainit(volatile struct lpc17_hcca_s *hcca);
 
 static struct lpc17_usbhost_s g_usbhost =
 {
-  .drvr           =
+  .drvr             =
     {
-	  .wait       = lpc17_wait,
-      .enumerate  = lpc17_enumerate,
-      .alloc      = lpc17_alloc,
-      .free       = lpc17_free,
-      .ctrlin     = lpc17_ctrlin,
-      .ctrlout    = lpc17_ctrlout,
-      .transfer   = lpc17_transfer,
-      .disconnect = lpc17_disconnect,
+	  .wait         = lpc17_wait,
+      .enumerate    = lpc17_enumerate,
+      .ep0configure = lpc17_ep0configure,
+      .alloc        = lpc17_alloc,
+      .free         = lpc17_free,
+      .ctrlin       = lpc17_ctrlin,
+      .ctrlout      = lpc17_ctrlout,
+      .transfer     = lpc17_transfer,
+      .disconnect   = lpc17_disconnect,
     },
-  .class          = NULL,
+  .class            = NULL,
 };
 
 /* This is a free list of EDs and TD buffers */
@@ -693,172 +696,6 @@ static int lpc17_ctrltd(struct lpc17_usbhost_s *priv, uint32_t dirpid,
 }
 
 /*******************************************************************************
- * Name: lpc17_devdesc
- *
- * Description:
- *   A configuration descriptor has been obtained from the device.  Find the
- *   ID information for the class that supports this device.
- *
- *******************************************************************************/
-
-static inline int lpc17_devdesc(struct lpc17_usbhost_s *priv,
-                                const struct usb_devdesc_s *devdesc, int desclen,
-                                struct usbhost_id_s *id)
-{
-  /* Clear the ID info */
-
-  memset(id, 0, sizeof(struct usbhost_id_s));
-
-  /* Check we have enough of the structure to see the ID info. */
-
-  if (desclen >= 7)
-    {
-      /* Pick off the ID info */
-
-      id->base     = devdesc->class;
-      id->subclass = devdesc->subclass;
-      id->proto    = devdesc->protocol;
-
-      /* Check if we have enough of the structure to see the VID/PID */
-
-      if (desclen >= 12)
-        {
-          /* Yes, then pick off the VID and PID as well */
-
-          id->vid = lpc17_getle16(devdesc->vendor);
-          id->pid = lpc17_getle16(devdesc->product);
-        }
-    }
-
-  return OK;
-}
-                                
-/*******************************************************************************
- * Name: lpc17_configdesc
- *
- * Description:
- *   A configuration descriptor has been obtained from the device.  Find the
- *   ID information for the class that supports this device.
- *
- *******************************************************************************/
-
-static inline int
-lpc17_configdesc(struct lpc17_usbhost_s *priv, const uint8_t *configdesc,
-                 int desclen, struct usbhost_id_s *id)
-{
-  struct usb_cfgdesc_s *cfgdesc;
-  struct usb_ifdesc_s *ifdesc;
-  int remaining;
-
-  DEBUGASSERT(priv != NULL && 
-              configdesc != NULL &&
-              desclen >= sizeof(struct usb_cfgdesc_s));
-  
-  /* Verify that we were passed a configuration descriptor */
-
-  cfgdesc = (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)lpc17_getle16(cfgdesc->totallen);
-
-  /* Skip to the next entry descriptor */
-
-  configdesc += cfgdesc->len;
-  remaining  -= cfgdesc->len;
-
-  /* Loop where there are more dscriptors to examine */
-
-  memset(&id, 0, sizeof(FAR struct usb_desc_s));
-  while (remaining >= sizeof(struct usb_desc_s))
-    {
-      /* What is the next descriptor? Is it an interface descriptor? */
-
-      ifdesc = (struct usb_ifdesc_s *)configdesc;
-      if (ifdesc->type == USB_DESC_TYPE_INTERFACE)
-        {
-          /* Yes, extract the class information from the interface descriptor.
-           * (We are going to need to do more than this here in the future:
-           *  ID information might lie elsewhere and we will need the VID and
-           *  PID as well).
-           */
- 
-          DEBUGASSERT(remaining >= sizeof(struct usb_ifdesc_s));
-          id->base     = ifdesc->class;
-          id->subclass = ifdesc->subclass;
-          id->proto    = ifdesc->protocol;
-          return OK;
-        }
-
-     /* Increment the address of the next descriptor */
- 
-      configdesc += ifdesc->len;
-      remaining  -= ifdesc->len;
-    }
-
-  return -ENOENT;
-}
-
-/*******************************************************************************
- * Name: lpc17_classbind
- *
- * Description:
- *   A configuration descriptor has been obtained from the device.  Try to
- *   bind this configuration descriptor with a supported class.
- *
- *******************************************************************************/
-
-static inline int lpc17_classbind(struct lpc17_usbhost_s *priv,
-                                  const uint8_t *configdesc, int desclen,
-                                  struct usbhost_id_s *id)
-{
-  const struct usbhost_registry_s *reg;
-  int ret = -EINVAL;
-
-  DEBUGASSERT(priv && priv->class == NULL);
-  if (id->base == USB_CLASS_VENDOR_SPEC)
-    {
-      udbg("BUG: More logic needed to extract VID and PID\n");
-    }
-
-  /* Is there is a class implementation registered to support this device. */
-
-  reg = usbhost_findclass(id);
-  uvdbg("usbhost_findclass: %p\n", reg);
-  if (reg)
-    {
-      /* Yes.. there is a class for this device.  Get an instance of
-       * its interface.
-       */
-
-      ret = -ENOMEM;
-      priv->class = CLASS_CREATE(reg, &priv->drvr, id);
-      uvdbg("CLASS_CREATE: %p\n", priv->class);
-      if (priv->class)
-        {
-          /* Then bind the newly instantiated class instance */
-
-          ret = CLASS_CONNECT(priv->class, configdesc, desclen);
-          if (ret != OK)
-            {
-              udbg("CLASS_CONNECT failed: %d\n", ret);
-              CLASS_DISCONNECTED(priv->class);
-              priv->class = NULL;
-            }
-        }
-    }
-
-  uvdbg("Returning: %d\n", ret);
-  return ret;
-}
-
-/*******************************************************************************
  * Name: lpc17_usbinterrupt
  *
  * Description:
@@ -1063,11 +900,6 @@ static int lpc17_wait(FAR struct usbhost_driver_s *drvr, bool connected)
 static int lpc17_enumerate(FAR struct usbhost_driver_s *drvr)
 {
   struct lpc17_usbhost_s *priv = (struct lpc17_usbhost_s *)drvr;
-  struct usb_ctrlreq_s *ctrlreq;
-  struct usbhost_id_s id;
-  unsigned int len;
-  uint8_t *buffer;
-  int  ret;
 
   /* Are we connected to a device?  The caller should have called the wait()
    * method first to be assured that a device is connected.
@@ -1080,27 +912,7 @@ static int lpc17_enumerate(FAR struct usbhost_driver_s *drvr)
       udbg("Not connected\n");
 	  return -ENODEV;
     }
-  uvdbg("Enumerate the device\n");
-
-  /* Allocate TD buffers for use in this function.  We will need two:
-   * One for the request and one for the data buffer.
-   */
-
-  ctrlreq = (struct usb_ctrlreq_s *)lpc17_tdalloc(priv);
-  if (!ctrlreq)
-    {
-      udbg("lpc17_tdalloc() failed\n");
-      return -ENOMEM;
-    }
-
-  buffer = lpc17_tdalloc(priv);
-  if (!buffer)
-    {
-      udbg("lpc17_tdalloc() failed\n");
-      ret = -ENOMEM;
-      goto errout;
-    }
-
+ 
   /* USB 2.0 spec says at least 50ms delay before port reset */
 
   up_mdelay(100);
@@ -1118,166 +930,44 @@ static int lpc17_enumerate(FAR struct usbhost_driver_s *drvr)
   lpc17_putreg(OHCI_RHPORTST_PRSC, LPC17_USBHOST_RHPORTST1);
   up_mdelay(200);
 
-  /* Set max pkt size = 8 */
-
-  EDCTRL->ctrl = 8 << ED_CONTROL_MPS_SHIFT;
-
-  /* Read first 8 bytes of the device descriptor */
-
-  ctrlreq->type = USB_REQ_DIR_IN|USB_REQ_RECIPIENT_DEVICE;
-  ctrlreq->req  = USB_REQ_GETDESCRIPTOR;
-  lpc17_putle16(ctrlreq->value, (USB_DESC_TYPE_DEVICE << 8));
-  lpc17_putle16(ctrlreq->index, 0);
-  lpc17_putle16(ctrlreq->len, 8);
-
-  ret = lpc17_ctrlin(drvr, ctrlreq, buffer);
-  if (ret != OK)
-    {
-      udbg("ERROR: GETDESCRIPTOR/DEVICE, lpc17_ctrlin returned %d\n", ret);
-      goto errout;
-    }
-
-  /* Extract info from the device descriptor */
-
-  {
-    struct usb_devdesc_s *devdesc = (struct usb_devdesc_s *)buffer;
-
-    /* Extract the max packetsize for endpoint 0 */
-
-    EDCTRL->ctrl = (uint32_t)(devdesc->mxpacketsize) << ED_CONTROL_MPS_SHIFT;
-    
-    /* Get class identification information from the device descriptor.  Most
-     * devices set this to USB_CLASS_PER_INTERFACE (zero) and provide the
-     * identification informatino in the interface descriptor(s).  That allows
-     * a device to support multiple, different classes.
-     */
-
-    (void)lpc17_devdesc(priv, devdesc, 8, &id);
-
-    /* NOTE: Additional logic is needed here.  We will need additional logic
-     * to (1) get the full device descriptor, (1) extract the vendor/product IDs
-     * and (2) extract the number of configurations from the (full) device
-     * descriptor.
-     */
-  }
-
-  /* Set the device address to 1 */
-
-  ctrlreq->type = USB_REQ_DIR_OUT|USB_REQ_RECIPIENT_DEVICE;
-  ctrlreq->req  = USB_REQ_SETADDRESS;
-  lpc17_putle16(ctrlreq->value, (1 << 8));
-  lpc17_putle16(ctrlreq->index, 0);
-  lpc17_putle16(ctrlreq->len, 0);
-
-  ret = lpc17_ctrlout(drvr, ctrlreq, NULL);
-  if (ret != OK)
-    {
-      udbg("ERROR: SETADDRESS lpc17_ctrlout returned %d\n", ret);
-      goto errout;
-    }
-  up_mdelay(2);
-
-  /* Modify control pipe with address 1 */
-
-  EDCTRL->ctrl = (EDCTRL->ctrl) | 1;
-
- /* Get the configuration descriptor (only), index == 0.  More logic is
-  * needed in order to handle devices with multiple configurations.
-  */
-
-  ctrlreq->type = USB_REQ_DIR_IN|USB_REQ_RECIPIENT_DEVICE;
-  ctrlreq->req  = USB_REQ_GETDESCRIPTOR;
-  lpc17_putle16(ctrlreq->value, (USB_DESC_TYPE_CONFIG << 8));
-  lpc17_putle16(ctrlreq->index, 0);
-  lpc17_putle16(ctrlreq->len, USB_SIZEOF_CFGDESC);
-
-  ret = lpc17_ctrlin(drvr, ctrlreq, buffer);
-  if (ret != OK)
-   {
-      udbg("ERROR: GETDESCRIPTOR/CONFIG, lpc17_ctrlin returned %d\n", ret);
-      goto errout;
-    }
-
-  /* Extract the full size of the configuration data */
-
-  len = ((struct usb_cfgdesc_s *)buffer)->len;
-
-  /* Get all of the configuration descriptor data, index == 0 */
-
-  ctrlreq->type = USB_REQ_DIR_IN|USB_REQ_RECIPIENT_DEVICE;
-  ctrlreq->req  = USB_REQ_GETDESCRIPTOR;
-  lpc17_putle16(ctrlreq->value, (USB_DESC_TYPE_CONFIG << 8));
-  lpc17_putle16(ctrlreq->index, 0);
-  lpc17_putle16(ctrlreq->len, len);
-
-  ret = lpc17_ctrlin(drvr, ctrlreq, buffer);
-  if (ret != OK)
-    {
-      udbg("ERROR: GETDESCRIPTOR/CONFIG, lpc17_ctrlin returned %d\n", ret);
-      goto errout;
-    }
-
-  /* Select device configuration 1 */
-
-  ctrlreq->type = USB_REQ_DIR_OUT|USB_REQ_RECIPIENT_DEVICE;
-  ctrlreq->req  = USB_REQ_SETCONFIGURATION;
-  lpc17_putle16(ctrlreq->value, 1);
-  lpc17_putle16(ctrlreq->index, 0);
-  lpc17_putle16(ctrlreq->len, 0);
+  /* Let the common usbhost_enumerate do all of the real work */
 
-  ret = lpc17_ctrlout(drvr, ctrlreq, NULL);
-  if (ret != OK)
-    {
-      udbg("ERROR: SETCONFIGURATION, lpc17_ctrlout returned %d\n", ret);
-      goto errout;
-    }
-
-  /* Free the TD that we were using for the request buffer.  It is not needed
-   * further here but it may be needed by the class driver during its connection
-   * operations.  NOTE:  lpc17_tdfree() can be called with a NULL pointer later.
-   */
- 
-  lpc17_tdfree(priv, (uint8_t*)ctrlreq);
-  ctrlreq = NULL;
-
-  /* Was the class identification information provided in the device descriptor?
-   * Or do we need to find it in the interface descriptor(s)?
-   */
-
-  if (id.base == USB_CLASS_PER_INTERFACE)
-    {
-      /* Get the class identification information for this device from the
-       * interface descriptor(s).  Hmmm.. More logic is need to handle the
-       * case of multiple interface descriptors.
-       */
-
-      ret = lpc17_configdesc(priv, buffer, len, &id);
-      if (ret != OK)
-        {
-          udbg("ERROR: lpc17_configdesc returned %d\n", ret);
-          goto errout;
-        }
-    }
-
-  /* Some devices may require this delay before initialization */
-
-  up_mdelay(100);
-
-  /* Parse the configuration descriptor and bind to the class instance for the
-   * device.  This needs to be the last thing done because the class driver
-   * will begin configuring the device.
-   */
+  uvdbg("Enumerate the device\n");
+  return usbhost_enumerate(drvr, &priv->class);
+}
 
-  ret = lpc17_classbind(priv, buffer, len, &id);
-  if (ret != OK)
-    {
-      udbg("ERROR: lpc17_classbind returned %d\n", ret);
-    }
+/************************************************************************************
+ * Name: DRVR_EP0CONFIGURE
+ *
+ * Description:
+ *   Configure endpoint 0.  This method is normally used internally by the
+ *   enumerate() method but is made available at the interface to support
+ *   an external implementation of the enumeration logic.
+ *
+ * Input Parameters:
+ *   drvr - The USB host driver instance obtained as a parameter from the call to
+ *      the class create() method.
+ *   funcno - The USB address of the function containing the endpoint that EP0
+ *     controls
+ *   maxpacketsize - The maximum number of bytes that can be sent to or
+ *    received from the endpoint in a single data packet
+ *
+ * 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.
+ *
+ ************************************************************************************/
 
-errout:
-  lpc17_tdfree(priv, buffer);
-  lpc17_tdfree(priv, (uint8_t*)ctrlreq);
-  return ret;
+static int lpc17_ep0configure(FAR struct usbhost_driver_s *drvr, uint8_t funcno,
+                              uint16_t maxpacketsize)
+{
+  DEBUGASSERT(drvr && funcno < 128 && maxpacketsize < 2048);
+  EDCTRL->ctrl = (uint32_t)funcno << ED_CONTROL_FA_SHIFT | 
+                 (uint32_t)maxpacketsize << ED_CONTROL_MPS_SHIFT;
+  return OK;
 }
 
 /*******************************************************************************
diff --git a/nuttx/drivers/usbhost/Make.defs b/nuttx/drivers/usbhost/Make.defs
index 539d42551..d1a34a941 100644
--- a/nuttx/drivers/usbhost/Make.defs
+++ b/nuttx/drivers/usbhost/Make.defs
@@ -38,5 +38,5 @@ USBHOST_CSRCS  =
 
 ifeq ($(CONFIG_USBHOST),y)
 USBHOST_CSRCS  += usbhost_registry.c usbhost_registerclass.c usbhost_findclass.c
-USBHOST_CSRCS  += usbhost_storage.c
+USBHOST_CSRCS  += usbhost_enumerate.c usbhost_storage.c
 endif
diff --git a/nuttx/drivers/usbhost/usbhost_enumerate.c b/nuttx/drivers/usbhost/usbhost_enumerate.c
new file mode 100755
index 000000000..60019416a
--- /dev/null
+++ b/nuttx/drivers/usbhost/usbhost_enumerate.c
@@ -0,0 +1,514 @@
+/*******************************************************************************
+ * drivers/usbhost/usbhost_enumerate.c
+ *
+ *   Copyright (C) 2010 Gregory Nutt. All rights reserved.
+ *   Authors: Gregory Nutt <spudmonkey@racsa.co.cr>
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ *
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in
+ *    the documentation and/or other materials provided with the
+ *    distribution.
+ * 3. Neither the name NuttX nor the names of its contributors may be
+ *    used to endorse or promote products derived from this software
+ *    without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
+ * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
+ * COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
+ * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
+ * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
+ * OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
+ * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
+ * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
+ * ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
+ * POSSIBILITY OF SUCH DAMAGE.
+ *
+ *******************************************************************************/
+
+/*******************************************************************************
+ * Included Files
+ *******************************************************************************/
+
+#include <nuttx/config.h>
+
+#include <sys/types.h>
+#include <stdint.h>
+#include <string.h>
+#include <errno.h>
+#include <assert.h>
+#include <debug.h>
+
+#include <nuttx/arch.h>
+#include <nuttx/usb/ohci.h>
+#include <nuttx/usb/usb.h>
+#include <nuttx/usb/usbhost.h>
+
+/*******************************************************************************
+ * Definitions
+ *******************************************************************************/
+
+/*******************************************************************************
+ * Private Types
+ *******************************************************************************/
+
+/*******************************************************************************
+ * Private Function Prototypes
+ *******************************************************************************/
+
+static inline uint16_t usbhost_getle16(const uint8_t *val);
+static void usbhost_putle16(uint8_t *dest, uint16_t val);
+
+static inline int usbhost_devdesc(const struct usb_devdesc_s *devdesc, int desclen,
+                                  struct usbhost_id_s *id);
+static inline int usbhost_configdesc(const uint8_t *configdesc, int desclen,
+                                     struct usbhost_id_s *id);
+static inline int usbhost_classbind(FAR struct usbhost_driver_s *drvr,
+                                    const uint8_t *configdesc, int desclen,
+                                    struct usbhost_id_s *id,
+                                    FAR struct usbhost_class_s **class);
+
+/*******************************************************************************
+ * Private Data
+ *******************************************************************************/
+
+/*******************************************************************************
+ * Public Data
+ *******************************************************************************/
+
+/*******************************************************************************
+ * Private Functions
+ *******************************************************************************/
+
+/****************************************************************************
+ * Name: usbhost_getle16
+ *
+ * Description:
+ *   Get a (possibly unaligned) 16-bit little endian 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.
+ *
+ *******************************************************************************/
+
+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_devdesc
+ *
+ * Description:
+ *   A configuration descriptor has been obtained from the device.  Find the
+ *   ID information for the class that supports this device.
+ *
+ *******************************************************************************/
+
+static inline int usbhost_devdesc(const struct usb_devdesc_s *devdesc,
+                                  int desclen, struct usbhost_id_s *id)
+{
+  /* Clear the ID info */
+
+  memset(id, 0, sizeof(struct usbhost_id_s));
+
+  /* Check we have enough of the structure to see the ID info. */
+
+  if (desclen >= 7)
+    {
+      /* Pick off the ID info */
+
+      id->base     = devdesc->class;
+      id->subclass = devdesc->subclass;
+      id->proto    = devdesc->protocol;
+
+      /* Check if we have enough of the structure to see the VID/PID */
+
+      if (desclen >= 12)
+        {
+          /* Yes, then pick off the VID and PID as well */
+
+          id->vid = usbhost_getle16(devdesc->vendor);
+          id->pid = usbhost_getle16(devdesc->product);
+        }
+    }
+
+  return OK;
+}
+                                
+/*******************************************************************************
+ * Name: usbhost_configdesc
+ *
+ * Description:
+ *   A configuration descriptor has been obtained from the device.  Find the
+ *   ID information for the class that supports this device.
+ *
+ *******************************************************************************/
+
+static inline int usbhost_configdesc(const uint8_t *configdesc, int desclen,
+                                     struct usbhost_id_s *id)
+{
+  struct usb_cfgdesc_s *cfgdesc;
+  struct usb_ifdesc_s *ifdesc;
+  int remaining;
+
+  DEBUGASSERT(configdesc != NULL &&
+              desclen >= sizeof(struct usb_cfgdesc_s));
+  
+  /* Verify that we were passed a configuration descriptor */
+
+  cfgdesc = (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 */
+
+  memset(&id, 0, sizeof(FAR struct usb_desc_s));
+  while (remaining >= sizeof(struct usb_desc_s))
+    {
+      /* What is the next descriptor? Is it an interface descriptor? */
+
+      ifdesc = (struct usb_ifdesc_s *)configdesc;
+      if (ifdesc->type == USB_DESC_TYPE_INTERFACE)
+        {
+          /* Yes, extract the class information from the interface descriptor.
+           * (We are going to need to do more than this here in the future:
+           *  ID information might lie elsewhere and we will need the VID and
+           *  PID as well).
+           */
+ 
+          DEBUGASSERT(remaining >= sizeof(struct usb_ifdesc_s));
+          id->base     = ifdesc->class;
+          id->subclass = ifdesc->subclass;
+          id->proto    = ifdesc->protocol;
+          return OK;
+        }
+
+     /* Increment the address of the next descriptor */
+ 
+      configdesc += ifdesc->len;
+      remaining  -= ifdesc->len;
+    }
+
+  return -ENOENT;
+}
+
+/*******************************************************************************
+ * Name: usbhost_classbind
+ *
+ * Description:
+ *   A configuration descriptor has been obtained from the device.  Try to
+ *   bind this configuration descriptor with a supported class.
+ *
+ *******************************************************************************/
+
+static inline int usbhost_classbind(FAR struct usbhost_driver_s *drvr,
+                                    const uint8_t *configdesc, int desclen,
+                                    struct usbhost_id_s *id,
+                                    FAR struct usbhost_class_s **class)
+{
+  FAR struct usbhost_class_s *devclass;
+  const struct usbhost_registry_s *reg;
+  int ret = -EINVAL;
+
+  if (id->base == USB_CLASS_VENDOR_SPEC)
+    {
+      udbg("BUG: More logic needed to extract VID and PID\n");
+    }
+
+  /* Is there is a class implementation registered to support this device. */
+
+  reg = usbhost_findclass(id);
+  uvdbg("usbhost_findclass: %p\n", reg);
+  if (reg)
+    {
+      /* Yes.. there is a class for this device.  Get an instance of
+       * its interface.
+       */
+
+      ret = -ENOMEM;
+      devclass = CLASS_CREATE(reg, drvr, id);
+      uvdbg("CLASS_CREATE: %p\n", devclass);
+      if (devclass)
+        {
+          /* Then bind the newly instantiated class instance */
+
+          ret = CLASS_CONNECT(devclass, configdesc, desclen);
+          if (ret != OK)
+            {
+              udbg("CLASS_CONNECT failed: %d\n", ret);
+              CLASS_DISCONNECTED(devclass);
+            }
+          else
+            {
+              *class = devclass;
+            }
+        }
+    }
+
+  uvdbg("Returning: %d\n", ret);
+  return ret;
+}
+
+/*******************************************************************************
+ * Public Functions
+ *******************************************************************************/
+
+/*******************************************************************************
+ * Name: usbhost_enumerate
+ *
+ * Description:
+ *   Enumerate the connected device.  As part of this enumeration process,
+ *   the driver will (1) get the device's configuration descriptor, (2)
+ *   extract the class ID info from the configuration descriptor, (3) call
+ *   usbhost_findclass() to find the class that supports this device, (4)
+ *   call the create() method on the struct usbhost_registry_s interface
+ *   to get a class instance, and finally (5) call the configdesc() method
+ *   of the struct usbhost_class_s interface.  After that, the class is in
+ *   charge of the sequence of operations.
+ *
+ * Input Parameters:
+ *   drvr - The USB host driver instance obtained as a parameter from the call to
+ *      the class create() method.
+ *
+ * Returned Values:
+ *   On success, zero (OK) is returned. On a failure, a negated errno value is
+ *   returned indicating the nature of the failure
+ *
+ * Assumptions:
+ *   - Only a single class bound to a single device is supported.
+ *   - Called from a single thread so no mutual exclusion is required.
+ *   - Never called from an interrupt handler.
+ *
+ *******************************************************************************/
+
+int usbhost_enumerate(FAR struct usbhost_driver_s *drvr,
+                      FAR struct usbhost_class_s **class)
+{
+  struct usb_ctrlreq_s *ctrlreq;
+  struct usbhost_id_s id;
+  size_t maxlen;
+  unsigned int len;
+  uint16_t maxpacketsize;
+  uint8_t *buffer;
+  int  ret;
+
+  DEBUGASSERT(drvr && class);
+
+  /* Allocate TD buffers for use in this function.  We will need two:
+   * One for the request and one for the data buffer.
+   */
+
+  ret = DRVR_ALLOC(drvr, (FAR uint8_t **)&ctrlreq, &maxlen);
+  if (ret != OK)
+    {
+      udbg("DRVR_ALLOC failed: %d\n", ret);
+      return ret;
+    }
+
+  ret = DRVR_ALLOC(drvr, &buffer, &maxlen);
+  if (ret != OK)
+    {
+      udbg("DRVR_ALLOC failed: %d\n", ret);
+      goto errout;
+    }
+
+  /* Set max pkt size = 8 */
+
+  DRVR_EP0CONFIGURE(drvr, 0, 8);
+
+  /* Read first 8 bytes of the device descriptor */
+
+  ctrlreq->type = USB_REQ_DIR_IN|USB_REQ_RECIPIENT_DEVICE;
+  ctrlreq->req  = USB_REQ_GETDESCRIPTOR;
+  usbhost_putle16(ctrlreq->value, (USB_DESC_TYPE_DEVICE << 8));
+  usbhost_putle16(ctrlreq->index, 0);
+  usbhost_putle16(ctrlreq->len, 8);
+
+  ret = DRVR_CTRLIN(drvr, ctrlreq, buffer);
+  if (ret != OK)
+    {
+      udbg("ERROR: GETDESCRIPTOR/DEVICE, DRVR_CTRLIN returned %d\n", ret);
+      goto errout;
+    }
+
+  /* Extract info from the device descriptor */
+
+  {
+    struct usb_devdesc_s *devdesc = (struct usb_devdesc_s *)buffer;
+
+    /* Extract the max packetsize for endpoint 0 */
+
+    DRVR_EP0CONFIGURE(drvr, 0, maxpacketsize);
+
+    /* Get class identification information from the device descriptor.  Most
+     * devices set this to USB_CLASS_PER_INTERFACE (zero) and provide the
+     * identification informatino in the interface descriptor(s).  That allows
+     * a device to support multiple, different classes.
+     */
+
+    (void)usbhost_devdesc(devdesc, 8, &id);
+
+    /* NOTE: Additional logic is needed here.  We will need additional logic
+     * to (1) get the full device descriptor, (1) extract the vendor/product IDs
+     * and (2) extract the number of configurations from the (full) device
+     * descriptor.
+     */
+  }
+
+  /* Set the device address to 1 */
+
+  ctrlreq->type = USB_REQ_DIR_OUT|USB_REQ_RECIPIENT_DEVICE;
+  ctrlreq->req  = USB_REQ_SETADDRESS;
+  usbhost_putle16(ctrlreq->value, (1 << 8));
+  usbhost_putle16(ctrlreq->index, 0);
+  usbhost_putle16(ctrlreq->len, 0);
+
+  ret = DRVR_CTRLOUT(drvr, ctrlreq, NULL);
+  if (ret != OK)
+    {
+      udbg("ERROR: SETADDRESS DRVR_CTRLOUT returned %d\n", ret);
+      goto errout;
+    }
+  up_mdelay(2);
+
+  /* Modify control pipe with function address 1 */
+
+  DRVR_EP0CONFIGURE(drvr, 1, maxpacketsize);
+
+ /* Get the configuration descriptor (only), index == 0.  More logic is
+  * needed in order to handle devices with multiple configurations.
+  */
+
+  ctrlreq->type = USB_REQ_DIR_IN|USB_REQ_RECIPIENT_DEVICE;
+  ctrlreq->req  = USB_REQ_GETDESCRIPTOR;
+  usbhost_putle16(ctrlreq->value, (USB_DESC_TYPE_CONFIG << 8));
+  usbhost_putle16(ctrlreq->index, 0);
+  usbhost_putle16(ctrlreq->len, USB_SIZEOF_CFGDESC);
+
+  ret = DRVR_CTRLIN(drvr, ctrlreq, buffer);
+  if (ret != OK)
+   {
+      udbg("ERROR: GETDESCRIPTOR/CONFIG, DRVR_CTRLIN returned %d\n", ret);
+      goto errout;
+    }
+
+  /* Extract the full size of the configuration data */
+
+  len = ((struct usb_cfgdesc_s *)buffer)->len;
+
+  /* Get all of the configuration descriptor data, index == 0 */
+
+  ctrlreq->type = USB_REQ_DIR_IN|USB_REQ_RECIPIENT_DEVICE;
+  ctrlreq->req  = USB_REQ_GETDESCRIPTOR;
+  usbhost_putle16(ctrlreq->value, (USB_DESC_TYPE_CONFIG << 8));
+  usbhost_putle16(ctrlreq->index, 0);
+  usbhost_putle16(ctrlreq->len, len);
+
+  ret = DRVR_CTRLIN(drvr, ctrlreq, buffer);
+  if (ret != OK)
+    {
+      udbg("ERROR: GETDESCRIPTOR/CONFIG, DRVR_CTRLIN returned %d\n", ret);
+      goto errout;
+    }
+
+  /* Select device configuration 1 */
+
+  ctrlreq->type = USB_REQ_DIR_OUT|USB_REQ_RECIPIENT_DEVICE;
+  ctrlreq->req  = USB_REQ_SETCONFIGURATION;
+  usbhost_putle16(ctrlreq->value, 1);
+  usbhost_putle16(ctrlreq->index, 0);
+  usbhost_putle16(ctrlreq->len, 0);
+
+  ret = DRVR_CTRLOUT(drvr, ctrlreq, NULL);
+  if (ret != OK)
+    {
+      udbg("ERROR: SETCONFIGURATION, DRVR_CTRLOUT returned %d\n", ret);
+      goto errout;
+    }
+
+  /* Free the TD that we were using for the request buffer.  It is not needed
+   * further here but it may be needed by the class driver during its connection
+   * operations.
+   */
+ 
+  DRVR_FREE(drvr, (uint8_t*)ctrlreq);
+  ctrlreq = NULL;
+
+  /* Was the class identification information provided in the device descriptor?
+   * Or do we need to find it in the interface descriptor(s)?
+   */
+
+  if (id.base == USB_CLASS_PER_INTERFACE)
+    {
+      /* Get the class identification information for this device from the
+       * interface descriptor(s).  Hmmm.. More logic is need to handle the
+       * case of multiple interface descriptors.
+       */
+
+      ret = usbhost_configdesc(buffer, len, &id);
+      if (ret != OK)
+        {
+          udbg("ERROR: usbhost_configdesc returned %d\n", ret);
+          goto errout;
+        }
+    }
+
+  /* Some devices may require this delay before initialization */
+
+  up_mdelay(100);
+
+  /* Parse the configuration descriptor and bind to the class instance for the
+   * device.  This needs to be the last thing done because the class driver
+   * will begin configuring the device.
+   */
+
+  ret = usbhost_classbind(drvr, buffer, len, &id, class);
+  if (ret != OK)
+    {
+      udbg("ERROR: usbhost_classbind returned %d\n", ret);
+    }
+
+errout:
+  if (buffer)
+    {
+      DRVR_FREE(drvr, buffer);
+    }
+
+  if (ctrlreq)
+    {
+      DRVR_FREE(drvr, (uint8_t*)ctrlreq);
+    }
+  return ret;
+}
diff --git a/nuttx/include/nuttx/usb/usbhost.h b/nuttx/include/nuttx/usb/usbhost.h
index fc4d6ad55..18753e1b8 100644
--- a/nuttx/include/nuttx/usb/usbhost.h
+++ b/nuttx/include/nuttx/usb/usbhost.h
@@ -196,6 +196,33 @@
 #define DRVR_ENUMERATE(drvr) ((drvr)->enumerate(drvr))
 
 /************************************************************************************
+ * Name: DRVR_EP0CONFIGURE
+ *
+ * Description:
+ *   Configure endpoint 0.  This method is normally used internally by the
+ *   enumerate() method but is made available at the interface to support
+ *   an external implementation of the enumeration logic.
+ *
+ * Input Parameters:
+ *   drvr - The USB host driver instance obtained as a parameter from the call to
+ *      the class create() method.
+ *   funcno - The USB address of the function containing the endpoint that EP0
+ *     controls
+ *   mps (maxpacketsize) - The maximum number of bytes that can be sent to or
+ *    received from the endpoint in a single data packet
+ *
+ * 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.
+ *
+ ************************************************************************************/
+
+#define DRVR_EP0CONFIGURE(drvr,funcno,mps) ((drvr)->ep0configure(drvr,funcno,mps))
+
+/************************************************************************************
  * Name: DRVR_ALLOC
  *
  * Description:
@@ -433,6 +460,14 @@ struct usbhost_driver_s
 
   int (*enumerate)(FAR struct usbhost_driver_s *drvr);
 
+  /* Configure endpoint 0.  This method is normally used internally by the
+   * enumerate() method but is made available at the interface to support
+   * an external implementation of the enumeration logic.
+   */
+
+  int (*ep0configure)(FAR struct usbhost_driver_s *drvr, uint8_t funcno,
+                      uint16_t maxpacketsize);
+
   /* Some hardware supports special memory in which transfer descriptors can
    * be accessed more efficiently.  The following methods provide a mechanism
    * to allocate and free the transfer descriptor memory.  If the underlying
@@ -597,6 +632,44 @@ EXTERN int usbhost_storageinit(void);
 
 EXTERN FAR struct usbhost_driver_s *usbhost_initialize(int controller);
 
+/*******************************************************************************
+ * Name: usbhost_enumerate
+ *
+ * Description:
+ *   This is a share-able implementation of most of the logic required by the
+ *   driver enumerate() method.  This logic within this method should be common
+ *   to all USB host drivers.
+ *
+ *   Enumerate the connected device.  As part of this enumeration process,
+ *   the driver will (1) get the device's configuration descriptor, (2)
+ *   extract the class ID info from the configuration descriptor, (3) call
+ *   usbhost_findclass() to find the class that supports this device, (4)
+ *   call the create() method on the struct usbhost_registry_s interface
+ *   to get a class instance, and finally (5) call the configdesc() method
+ *   of the struct usbhost_class_s interface.  After that, the class is in
+ *   charge of the sequence of operations.
+ *
+ * Input Parameters:
+ *   drvr - The USB host driver instance obtained as a parameter from the call to
+ *      the class create() method.
+ *   class - If the class driver for the device is successful located
+ *      and bound to the driver, the allocated class instance is returned into
+ *      this caller-provided memory location.
+ *
+ * Returned Values:
+ *   On success, zero (OK) is returned. On a failure, a negated errno value is
+ *   returned indicating the nature of the failure
+ *
+ * Assumptions:
+ *   - Only a single class bound to a single device is supported.
+ *   - Called from a single thread so no mutual exclusion is required.
+ *   - Never called from an interrupt handler.
+ *
+ *******************************************************************************/
+
+EXTERN int usbhost_enumerate(FAR struct usbhost_driver_s *drvr,
+                             FAR struct usbhost_class_s **class);
+
 #undef EXTERN
 #if defined(__cplusplus)
 }