From 042da0c84ccdc86ff3085f2a8f18fe33fa7b65c7 Mon Sep 17 00:00:00 2001
From: patacongo <patacongo@42af7a65-404d-4744-a932-0658087f49c3>
Date: Tue, 11 Jan 2011 01:41:06 +0000
Subject: Improve endpoint management

git-svn-id: svn://svn.code.sf.net/p/nuttx/code/trunk@3240 42af7a65-404d-4744-a932-0658087f49c3
---
 nuttx/ChangeLog                            |   3 +-
 nuttx/Documentation/NuttX.html             |  71 +---
 nuttx/arch/arm/src/lpc17xx/lpc17_ohciram.h |   8 +-
 nuttx/arch/arm/src/lpc17xx/lpc17_usbhost.c | 244 +++++++-------
 nuttx/configs/nucleus2g/README.txt         |   4 +-
 nuttx/configs/olimex-lpc1766stk/README.txt |   4 +-
 nuttx/drivers/usbhost/usbhost_storage.c    | 511 ++++++++++++++++-------------
 nuttx/include/nuttx/usb/usbhost.h          |  90 ++++-
 8 files changed, 520 insertions(+), 415 deletions(-)

diff --git a/nuttx/ChangeLog b/nuttx/ChangeLog
index d6a03b732..1d781751f 100644
--- a/nuttx/ChangeLog
+++ b/nuttx/ChangeLog
@@ -1405,7 +1405,7 @@
 	* include/nuttx/spi.h -- the SPI_SETBITS macro was calling the setmode method.
 	  This is a very important bug-fix in some usages.
 
-5.16 2011-xx-xx Gregory Nutt <spudmonkey@racsa.co.cr>
+5.16 2011-01-10 Gregory Nutt <spudmonkey@racsa.co.cr>
 
 	* include/nuttx/usb -- Created new directory.  Moved all usb-related header
 	  files to this new directory.  Created a skeleton for a new USB host header
@@ -1418,3 +1418,4 @@
 	* drivers/usbhost -- Add a USB host class driver for the (Bulk-Only) USB
 	  Mass Storage Class.
 
+5.17 2011-xx-xx Gregory Nutt <spudmonkey@racsa.co.cr>
diff --git a/nuttx/Documentation/NuttX.html b/nuttx/Documentation/NuttX.html
index 34bdedec5..011f69b63 100644
--- a/nuttx/Documentation/NuttX.html
+++ b/nuttx/Documentation/NuttX.html
@@ -8,7 +8,7 @@
   <tr align="center" bgcolor="#e4e4e4">
     <td>
       <h1><big><font color="#3c34ec"><i>NuttX RTOS</i></font></big></h1>
-      <p>Last Updated: January 9, 2011</p>
+      <p>Last Updated: January 10, 2011</p>
     </td>
   </tr>
 </table>
@@ -1969,50 +1969,18 @@ Other memory:
 </table>
 
 <ul><pre>
-5.15 2010-12-12 Gregory Nutt &lt;spudmonkey@racsa.co.cr&gt;
-
-    * net/uip/uip_tcpaddsend.c and net/send.c -- Another place where the TCP sequence
-      number problem &quot;fixed&quot; in 5.14 might occur.
-    * net/send.c -- Check if the destination IP address is in the ARP table.  If
-      not, then don't consider the packet sent.  It won't be, an ARP packet will go
-      out instead.  This improves behavior, for example, on the first GET request
-      from a browser.
-    * arch/arm/src/lpc17xx/lpc17_emacram.h and lpc17_allocateheap.c -- The Ethernet
-      logic was using all of AHB SRAM Bank0 for Ethernet packet buffers (16Kb).  An
-      option was added to limit the amount of SRAM used for packet buffering and to
-      re-use any extra Bank0 memory for heap.  configs/olimex-lpc1766stk/nettest
-      now uses only 8Kb at the beginning of Bank0; the 8Kb at the end of Bank0 is
-      included in the heap
-    * arch/arm/src/lpc17xx/lpc17_ssp.c -- Fix compilation errors when SSP1 is
-      selected.
-    * configs/olimex-lpc1766stk/nsh -- Enable network and SD/MMC card support in
-      NSH.  Networking and telnetd interface as well as SPI-based microSD are
-      now functional.
-    * examples/nsh/nsh_netinit.c -- Fix NSH bug.  If CONFIG_NET is selected, but
-      CONFIG_EXAMPLES_NSH_TELNETD is not selected, then the network is never
-      initialized and bad things happen if you try to ping.
-    * drivers/lcd -- Add header files for the Phillips PCF8833 LCD controller and
-      for the Epson S1D15G10 LCD controller.  A driver for the Nokia 6100 LCD is
-      coming.
-    * include/nuttx/spi.h and almost all other SPI files -- Added an optional
-      cmddata() method to the SPI interface.  Some devices require an additional
-      out-of-band bit to specify if the next word sent to the device is a command
-      or data. This is typical, for example, in &quot;9-bit&quot; displays where the 9th bit
-      is the CMD/DATA bit. The cmddata method provides selection of command or data.
-    * drivers/lcd/p14201.c -- Now uses the cmddata() method of the SPI interface.
-    * arch/arm/src/lpc17xx/lpc17_usbdev.c -- LPC17xx USB driver now appears to
-      to be fully functional.  examples/usbstorage configuration verified (the
-      examples/usbserial configuration is untested).
-    * drivers/usbdev/usbserial.c and usbstorage.c -- All USB class drivers need
-      to call DEV_CONNECT() when they are ready to be enumerated.  That is,
-      (1) initially when bound to the USB driver, and (2) after a USB reset.
-    * drivers/lcd/nokia6100.c -- A driver for the Nokia 6100 LCD.  This driver
-      has not be verified as of the initial check-in.
-    * configs/olimex-lpc1766stk/nx -- A NX graphics configuration for the Olimex
-      LPC1766-STK board using the Nokia 6100 LCD driver.  This configuration has
-      not been verified as of the initial check-in.
-    * include/nuttx/spi.h -- the SPI_SETBITS macro was calling the setmode method.
-      This is a very important bug-fix in some usages.
+nuttx-5.16 2011-01-10 Gregory Nutt &lt;spudmonkey@racsa.co.cr&gt;
+
+    * include/nuttx/usb -- Created new directory.  Moved all usb-related header
+      files to this new directory.  Created a skeleton for a new USB host header
+      file
+    * drivers/usbhost -- Add USB host "registry" where connect devices can be
+      matched with the correct USB class driver.
+    * arc/arc/src/lpc17xx/lpc17_usbhost.c -- Add a simple USB host driver for
+      the NXP lpc17xx.
+    * drivers/usbhost -- Add generic USB device enumeration logic.
+    * drivers/usbhost -- Add a USB host class driver for the (Bulk-Only) USB
+      Mass Storage Class.
 
 pascal-2.0 2009-12-21 Gregory Nutt &lt;spudmonkey@racsa.co.cr&gt;
 
@@ -2042,18 +2010,7 @@ buildroot-1.8 2009-12-21 &lt;spudmonkey@racsa.co.cr&gt;
 </table>
 
 <ul><pre>
-nuttx-5.16 2011-xx-xx Gregory Nutt &lt;spudmonkey@racsa.co.cr&gt;
-
-    * include/nuttx/usb -- Created new directory.  Moved all usb-related header
-      files to this new directory.  Created a skeleton for a new USB host header
-      file
-    * drivers/usbhost -- Add USB host "registry" where connect devices can be
-      matched with the correct USB class driver.
-    * arc/arc/src/lpc17xx/lpc17_usbhost.c -- Add a simple USB host driver for
-      the NXP lpc17xx.
-    * drivers/usbhost -- Add generic USB device enumeration logic.
-    * drivers/usbhost -- Add a USB host class driver for the (Bulk-Only) USB
-      Mass Storage Class.
+nuttx-5.17 2011-xx-xx Gregory Nutt &lt;spudmonkey@racsa.co.cr&gt;
 
 pascal-2.1 2010-xx-xx Gregory Nutt &lt;spudmonkey@racsa.co.cr&gt;
 
diff --git a/nuttx/arch/arm/src/lpc17xx/lpc17_ohciram.h b/nuttx/arch/arm/src/lpc17xx/lpc17_ohciram.h
index d2fc11248..0e9f81ecb 100755
--- a/nuttx/arch/arm/src/lpc17xx/lpc17_ohciram.h
+++ b/nuttx/arch/arm/src/lpc17xx/lpc17_ohciram.h
@@ -214,10 +214,10 @@
 
 /* Finally, use the remainder of the allocated OHCI for IO buffers */
 
-#define LPC17_IOBUFFERS     ((LPC17_OHCIRAM_END - LPC17_IOFREE_BASE) / CONFIG_USBHOST_IOBUFSIZE)
-
-#if LPC17_IOBUFFERS < 1
-#  warning "No IO buffers allocated"
+#if CONFIG_USBHOST_IOBUFSIZE > 0
+#  define LPC17_IOBUFFERS   ((LPC17_OHCIRAM_END - LPC17_IOFREE_BASE) / CONFIG_USBHOST_IOBUFSIZE)
+#else
+#  define LPC17_IOBUFFERS 0
 #endif
 
 /************************************************************************************
diff --git a/nuttx/arch/arm/src/lpc17xx/lpc17_usbhost.c b/nuttx/arch/arm/src/lpc17xx/lpc17_usbhost.c
index 950a0ffe7..917ecd2e5 100755
--- a/nuttx/arch/arm/src/lpc17xx/lpc17_usbhost.c
+++ b/nuttx/arch/arm/src/lpc17xx/lpc17_usbhost.c
@@ -71,15 +71,13 @@
  * Definitions
  *******************************************************************************/
 
-/* I think it is the case that all I/O buffers must lie in AHB SRAM because of
- * the OHCI DMA.  But this definition has here so that I can experiment later
- * to see if this really required.
+/* All I/O buffers must lie in AHB SRAM because of the OHCI DMA. It might be
+ * okay if no I/O buffers are used *IF* the application can guarantee that all
+ * end-user I/O buffers reside in AHB SRAM.
  */
 
-#define CONFIG_UBHOST_AHBIOBUFFERS 1
-
-#if defined(CONFIG_UBHOST_AHBIOBUFFERS) && LPC17_IOBUFFERS < 1
-#  error "No IO buffers allocated"
+#if LPC17_IOBUFFERS < 1
+#  warning "No IO buffers allocated"
 #endif
 
 /* Frame Interval / Periodic Start */
@@ -206,11 +204,9 @@ static void lpc17_putle16(uint8_t *dest, uint16_t val);
 
 /* Descriptor helper functions *************************************************/
 
-static struct ohci_ed_s *lpc17_edalloc(struct lpc17_usbhost_s *priv);
-static void lpc17_edfree(struct lpc17_usbhost_s *priv, struct ohci_ed_s *ed);
 static uint8_t *lpc17_tdalloc(struct lpc17_usbhost_s *priv);
 static void lpc17_tdfree(struct lpc17_usbhost_s *priv, uint8_t *buffer);
-#ifdef CONFIG_UBHOST_AHBIOBUFFERS
+#if LPC17_IOBUFFERS > 0
 static uint8_t *lpc17_ioalloc(struct lpc17_usbhost_s *priv);
 static void lpc17_iofree(struct lpc17_usbhost_s *priv, uint8_t *buffer);
 #endif
@@ -230,6 +226,9 @@ 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 funcaddr,
                               uint16_t maxpacketsize);
+static int lpc17_epalloc(FAR struct usbhost_driver_s *drvr,
+                         const FAR struct usbhost_epdesc_s *epdesc, usbhost_ep_t *ep);
+static int lpc17_epfree(FAR struct usbhost_driver_s *drvr, usbhost_ep_t ep);
 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);
@@ -239,8 +238,7 @@ static int lpc17_ctrlin(FAR struct usbhost_driver_s *drvr,
 static int lpc17_ctrlout(FAR struct usbhost_driver_s *drvr,
                          FAR const struct usb_ctrlreq_s *req,
                          FAR const uint8_t *buffer);
-static int lpc17_transfer(FAR struct usbhost_driver_s *drvr,
-                          FAR struct usbhost_epdesc_s *ed,
+static int lpc17_transfer(FAR struct usbhost_driver_s *drvr, usbhost_ep_t ep,
                           FAR uint8_t *buffer, size_t buflen);
 static void lpc17_disconnect(FAR struct usbhost_driver_s *drvr);
   
@@ -266,6 +264,8 @@ static struct lpc17_usbhost_s g_usbhost =
       .wait         = lpc17_wait,
       .enumerate    = lpc17_enumerate,
       .ep0configure = lpc17_ep0configure,
+      .epalloc      = lpc17_epalloc,
+      .epfree       = lpc17_epfree,
       .alloc        = lpc17_alloc,
       .free         = lpc17_free,
       .ctrlin       = lpc17_ctrlin,
@@ -280,7 +280,7 @@ static struct lpc17_usbhost_s g_usbhost =
 
 static struct lpc17_edlist_s  *g_edfree;
 static struct lpc17_buflist_s *g_tdfree;
-#ifdef CONFIG_UBHOST_AHBIOBUFFERS
+#if LPC17_IOBUFFERS > 0
 static struct lpc17_buflist_s *g_iofree;
 #endif
 
@@ -464,39 +464,6 @@ static void lpc17_putle16(uint8_t *dest, uint16_t val)
   dest[1] = val >> 8;
 }
 
-/*******************************************************************************
- * Name: lpc17_edalloc
- *
- * Description:
- *   Allocate an ED from the free list
- *
- *******************************************************************************/
-
-static struct ohci_ed_s *lpc17_edalloc(struct lpc17_usbhost_s *priv)
-{
-  struct ohci_ed_s *ret = (struct ohci_ed_s *)g_edfree;
-  if (ret)
-    {
-      g_edfree = ((struct lpc17_edlist_s*)ret)->flink;
-    }
-  return ret;
-}
-
-/*******************************************************************************
- * Name: lpc17_edfree
- *
- * Description:
- *   Return an ED to the free list
- *
- *******************************************************************************/
-
-static void lpc17_edfree(struct lpc17_usbhost_s *priv, struct ohci_ed_s *ed)
-{
-  struct lpc17_edlist_s *edfree = (struct lpc17_edlist_s *)ed;
-  edfree->flink                 = g_edfree;
-  g_edfree                      = edfree;
-}
-
 /*******************************************************************************
  * Name: lpc17_tdalloc
  *
@@ -550,7 +517,7 @@ static void lpc17_tdfree(struct lpc17_usbhost_s *priv, uint8_t *buffer)
  *
  *******************************************************************************/
 
-#ifdef CONFIG_UBHOST_AHBIOBUFFERS
+#if LPC17_IOBUFFERS > 0
 static uint8_t *lpc17_ioalloc(struct lpc17_usbhost_s *priv)
 {
   uint8_t *ret = (uint8_t *)g_iofree;
@@ -570,7 +537,7 @@ static uint8_t *lpc17_ioalloc(struct lpc17_usbhost_s *priv)
  *
  *******************************************************************************/
 
-#ifdef CONFIG_UBHOST_AHBIOBUFFERS
+#if LPC17_IOBUFFERS > 0
 static void lpc17_iofree(struct lpc17_usbhost_s *priv, uint8_t *buffer)
 {
   struct lpc17_buflist_s *iofree = (struct lpc17_buflist_s *)buffer;
@@ -1067,6 +1034,104 @@ static int lpc17_ep0configure(FAR struct usbhost_driver_s *drvr, uint8_t funcadd
   return OK;
 }
 
+/************************************************************************************
+ * Name: lpc17_epalloc
+ *
+ * Description:
+ *   Allocate and configure one endpoint.
+ *
+ * Input Parameters:
+ *   drvr - The USB host driver instance obtained as a parameter from the call to
+ *      the class create() method.
+ *   epdesc - Describes the endpoint to be allocated.
+ *   ep - A memory location provided by the caller in which to receive the
+ *      allocated endpoint desciptor.
+ *
+ * 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 lpc17_epalloc(FAR struct usbhost_driver_s *drvr,
+                         const FAR struct usbhost_epdesc_s *epdesc, usbhost_ep_t *ep)
+{
+  struct ohci_ed_s *ed;
+  int ret = -ENOMEM;
+
+  DEBUGASSERT(epdesc && ep);
+
+  /* Take the next ED from the beginning of the free list */
+
+  ed = (struct ohci_ed_s *)g_edfree;
+  if (ed)
+    {
+      /* Remove the ED from the freelist */
+
+      g_edfree = ((struct lpc17_edlist_s*)ed)->flink;
+
+      /* Configure the endpoint descriptor. */
+ 
+      lpc17_edinit(ed);
+      ed->ctrl = (uint32_t)(epdesc->funcaddr)     << ED_CONTROL_FA_SHIFT | 
+                 (uint32_t)(epdesc->addr)         << ED_CONTROL_EN_SHIFT |
+                 (uint32_t)(epdesc->mxpacketsize) << ED_CONTROL_MPS_SHIFT;
+
+      /* Get the direction of the endpoint */
+
+      if (epdesc->in != 0)
+        {
+          ed->ctrl |= ED_CONTROL_D_IN;
+        }
+      else
+        {
+          ed->ctrl |= ED_CONTROL_D_OUT;
+        }
+
+      /* Return an opaque reference to the ED */
+
+      *ep      = (usbhost_ep_t)ed;
+      ret      = OK;
+    }
+  return ret;
+}
+
+/************************************************************************************
+ * Name: lpc17_epfree
+ *
+ * Description:
+ *   Free and endpoint previously allocated by DRVR_EPALLOC.
+ *
+ * Input Parameters:
+ *   drvr - The USB host driver instance obtained as a parameter from the call to
+ *      the class create() method.
+ *   ep - The endpint to be freed.
+ *
+ * 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 lpc17_epfree(FAR struct usbhost_driver_s *drvr, usbhost_ep_t ep)
+{
+  struct lpc17_edlist_s *ed = (struct lpc17_edlist_s *)ep;
+
+  DEBUGASSERT(ed);
+
+  /* Put the ED back into the free list */
+
+  ed->flink = g_edfree;
+  g_edfree  = ed;
+  return OK;
+}
+
 /*******************************************************************************
  * Name: lpc17_alloc
  *
@@ -1251,7 +1316,7 @@ static int lpc17_ctrlout(FAR struct usbhost_driver_s *drvr,
  * Input Parameters:
  *   drvr - The USB host driver instance obtained as a parameter from the call to
  *      the class create() method.
- *   ed - The IN or OUT endpoint descriptor for the device endpoint on which to
+ *   ep - The IN or OUT endpoint descriptor for the device endpoint on which to
  *      perform the transfer.
  *   buffer - A buffer containing the data to be sent (OUT endpoint) or received
  *     (IN endpoint).  buffer must have been allocated using DRVR_ALLOC
@@ -1268,26 +1333,32 @@ static int lpc17_ctrlout(FAR struct usbhost_driver_s *drvr,
  *
  *******************************************************************************/
 
-static int lpc17_transfer(FAR struct usbhost_driver_s *drvr,
-                          FAR struct usbhost_epdesc_s *ep,
+static int lpc17_transfer(FAR struct usbhost_driver_s *drvr, usbhost_ep_t ep,
                           FAR uint8_t *buffer, size_t buflen)
 {
   struct lpc17_usbhost_s *priv = (struct lpc17_usbhost_s *)drvr;
-  struct ohci_ed_s *ed = NULL;
+  struct ohci_ed_s *ed = (struct ohci_ed_s *)ep;
   uint32_t dirpid;
   uint32_t regval;
-#ifdef CONFIG_UBHOST_AHBIOBUFFERS
+#if LPC17_IOBUFFERS > 0
   uint8_t *origbuf = NULL;
 #endif
+  bool in;
   int ret;
 
-  DEBUGASSERT(drvr && ep && buffer && buflen > 0);
+  DEBUGASSERT(priv && ed && buffer && buflen > 0);
+
+  in = (ed->ctrl  & ED_CONTROL_D_MASK) == ED_CONTROL_D_IN;
   uvdbg("EP%d %s toggle:%d maxpacket:%d buflen:%d\n",
-        ep->addr, ep->in ? "IN" : "OUT", ep->toggle, ep->mxpacketsize, buflen);
+        (ed->ctrl  & ED_CONTROL_EN_MASK)  >> ED_CONTROL_EN_SHIFT, 
+        in ? "IN" : "OUT",
+        (ed->headp & ED_HEADP_C)          != 0 ? 1 : 0,
+        (ed->ctrl  & ED_CONTROL_MPS_MASK) >> ED_CONTROL_MPS_SHIFT, 
+        buflen);
 
   /* Allocate an IO buffer if the user buffer does not lie in AHB SRAM */
 
-#ifdef CONFIG_UBHOST_AHBIOBUFFERS
+#if LPC17_IOBUFFERS > 0
   if ((uintptr_t)buffer < LPC17_SRAM_BANK0 ||
       (uintptr_t)buffer >= (LPC17_SRAM_BANK0 + LPC17_BANK0_SIZE + LPC17_BANK1_SIZE))
     {
@@ -1318,7 +1389,7 @@ static int lpc17_transfer(FAR struct usbhost_driver_s *drvr,
        * way around this copy.
        */
 
-      if (ep->in == 0)
+      if (!in)
         {
           memcpy(buffer, origbuf, buflen);
         }
@@ -1336,45 +1407,17 @@ static int lpc17_transfer(FAR struct usbhost_driver_s *drvr,
       goto errout;
     }
 
-  /* Allocate an ED */
-
-  ed = lpc17_edalloc(priv);
-  if (!ed)
-    {
-      udbg("ED allocation failed\n");
-      ret = -ENOMEM;
-      goto errout;
-    }
-
-  /* Format the endpoint descriptor.  This could be a lot simpler if
-   * the OHCI ED structure were exposed outside of the driver.
-   */
- 
-  lpc17_edinit(ed);
-  ed->ctrl = (uint32_t)(ep->funcaddr)     << ED_CONTROL_FA_SHIFT | 
-             (uint32_t)(ep->addr)         << ED_CONTROL_EN_SHIFT |
-             (uint32_t)(ep->mxpacketsize) << ED_CONTROL_MPS_SHIFT;
-
   /* Get the direction of the endpoint */
 
-  if (ep->in != 0)
+  if (in)
     {
-      ed->ctrl |= ED_CONTROL_D_IN;
       dirpid    = GTD_STATUS_DP_IN;
     }
   else
     {
-      ed->ctrl |= ED_CONTROL_D_OUT;
       dirpid    = GTD_STATUS_DP_OUT;
     }
 
-  /* Set/restore the toggle carry bit */
-
-  if (ep->toggle)
-    {
-      ed->headp = ED_HEADP_C;
-    }
-
   /* Then enqueue the transfer */
 
   priv->tdstatus = TD_CC_NOERROR;
@@ -1420,24 +1463,10 @@ static int lpc17_transfer(FAR struct usbhost_driver_s *drvr,
       ret = -EIO;
     }
 
-  /* Save the toggle carry bit.  This bit is updated each time that an
-   * ED is retired.  This could be a lot simpler if the OHCI ED structure
-   * were exposed outside of the driver.
-   */
-
-  if ((ed->headp & ED_HEADP_C) != 0)
-    {
-      ep->toggle = 1;
-    }
-  else
-    {
-      ep->toggle = 0;
-    }
-
 errout:
   /* Free any temporary IO buffers */
 
-#ifdef CONFIG_UBHOST_AHBIOBUFFERS
+#if LPC17_IOBUFFERS > 0
   if (buffer && origbuf)
     {
       /* If this is an IN transaction, get the user data from the AHB
@@ -1446,7 +1475,7 @@ errout:
        * way around this copy.
        */
 
-      if (ep->in != 0 && ret == OK)
+      if (in && ret == OK)
         {
           memcpy(origbuf, buffer, buflen);
         }
@@ -1457,13 +1486,6 @@ errout:
     }
 #endif
 
-  /* Free the endpoint descriptor */
-
-  if (ed)
-    {
-      lpc17_edfree(priv, ed);
-    }
-
   return ret;
 }
 
@@ -1644,7 +1666,7 @@ FAR struct usbhost_driver_s *usbhost_initialize(int controller)
     {
       /* Put the ED in a free list */
 
-      lpc17_edfree(priv, &EDFREE[i]);
+      lpc17_epfree(&priv->drvr, (usbhost_ep_t)&EDFREE[i]);
     }
 
   /* Initialize user-configurable TD buffers */
@@ -1658,7 +1680,7 @@ FAR struct usbhost_driver_s *usbhost_initialize(int controller)
       buffer += CONFIG_USBHOST_TDBUFSIZE;
     }
 
-#ifdef CONFIG_UBHOST_AHBIOBUFFERS
+#if LPC17_IOBUFFERS > 0
   /* Initialize user-configurable IO buffers */
 
   buffer = IOFREE;
diff --git a/nuttx/configs/nucleus2g/README.txt b/nuttx/configs/nucleus2g/README.txt
index 21b04a08f..4d88654c5 100755
--- a/nuttx/configs/nucleus2g/README.txt
+++ b/nuttx/configs/nucleus2g/README.txt
@@ -443,7 +443,9 @@ Nucleus 2G Configuration Options
     CONFIG_USBHOST_TDBUFSIZE
       Size of one transfer descriptor buffer
     CONFIG_USBHOST_IOBUFSIZE
-      Size of one end-user I/O buffer
+      Size of one end-user I/O buffer.  This can be zero if the
+      application can guarantee that all end-user I/O buffers
+      reside in AHB SRAM.
 
 USB Host Configuration
 ^^^^^^^^^^^^^^^^^^^^^^
diff --git a/nuttx/configs/olimex-lpc1766stk/README.txt b/nuttx/configs/olimex-lpc1766stk/README.txt
index cd7a1ca49..eae9685ea 100755
--- a/nuttx/configs/olimex-lpc1766stk/README.txt
+++ b/nuttx/configs/olimex-lpc1766stk/README.txt
@@ -689,7 +689,9 @@ Olimex LPC1766-STK Configuration Options
     CONFIG_USBHOST_TDBUFSIZE
       Size of one transfer descriptor buffer
     CONFIG_USBHOST_IOBUFSIZE
-      Size of one end-user I/O buffer
+      Size of one end-user I/O buffer.  This can be zero if the
+      application can guarantee that all end-user I/O buffers
+      reside in AHB SRAM.
 
 USB Host Configuration
 ^^^^^^^^^^^^^^^^^^^^^^
diff --git a/nuttx/drivers/usbhost/usbhost_storage.c b/nuttx/drivers/usbhost/usbhost_storage.c
index c13e32bb8..e0f4dc4ad 100644
--- a/nuttx/drivers/usbhost/usbhost_storage.c
+++ b/nuttx/drivers/usbhost/usbhost_storage.c
@@ -129,8 +129,8 @@ struct usbhost_state_s
   struct work_s           work;         /* For interacting with the worker thread */
   FAR uint8_t            *tdbuffer;     /* The allocated transfer descriptor buffer */
   size_t                  tdbuflen;     /* Size of the allocated transfer buffer */
-  struct usbhost_epdesc_s bulkin;       /* Bulk IN endpoint */
-  struct usbhost_epdesc_s bulkout;      /* Bulk OUT endpoint */
+  usbhost_ep_t            bulkin;       /* Bulk IN endpoint */
+  usbhost_ep_t            bulkout;      /* Bulk OUT endpoint */
 };
 
 /****************************************************************************
@@ -186,8 +186,10 @@ static inline int usbhost_inquiry(FAR struct usbhost_state_s *priv);
 /* Worker thread actions */
 
 static void usbhost_destroy(FAR void *arg);
-static void usbhost_initvolume(FAR void *arg);
-static void usbhost_work(FAR struct usbhost_state_s *priv, worker_t worker);
+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_initvolume(FAR struct usbhost_state_s *priv);
 
 /* (Little Endian) Data helpers */
 
@@ -690,13 +692,13 @@ static inline int usbhost_testunitready(FAR struct usbhost_state_s *priv)
   /* Construct and send the CBW */
  
   usbhost_testunitreadycbw(cbw);
-  result = DRVR_TRANSFER(priv->drvr, &priv->bulkout,
+  result = DRVR_TRANSFER(priv->drvr, priv->bulkout,
                         (uint8_t*)cbw, USBSTRG_CBW_SIZEOF);
   if (result == OK)
     {
       /* Receive the CSW */
 
-      result = DRVR_TRANSFER(priv->drvr, &priv->bulkin,
+      result = DRVR_TRANSFER(priv->drvr, priv->bulkin,
                              priv->tdbuffer, USBSTRG_CSW_SIZEOF);
       if (result == OK)
         {
@@ -723,19 +725,19 @@ static inline int usbhost_requestsense(FAR struct usbhost_state_s *priv)
   /* Construct and send the CBW */
  
   usbhost_requestsensecbw(cbw);
-  result = DRVR_TRANSFER(priv->drvr, &priv->bulkout,
+  result = DRVR_TRANSFER(priv->drvr, priv->bulkout,
                         (uint8_t*)cbw, USBSTRG_CBW_SIZEOF);
   if (result == OK)
     {
       /* Receive the sense data response */
 
-      result = DRVR_TRANSFER(priv->drvr, &priv->bulkin,
+      result = DRVR_TRANSFER(priv->drvr, priv->bulkin,
                              priv->tdbuffer, SCSIRESP_FIXEDSENSEDATA_SIZEOF);
       if (result == OK)
         {
           /* Receive the CSW */
 
-          result = DRVR_TRANSFER(priv->drvr, &priv->bulkin,
+          result = DRVR_TRANSFER(priv->drvr, priv->bulkin,
                                  priv->tdbuffer, USBSTRG_CSW_SIZEOF);
           if (result == OK)
             {
@@ -765,13 +767,13 @@ static inline int usbhost_readcapacity(FAR struct usbhost_state_s *priv)
   /* Construct and send the CBW */
  
   usbhost_readcapacitycbw(cbw);
-  result = DRVR_TRANSFER(priv->drvr, &priv->bulkout,
+  result = DRVR_TRANSFER(priv->drvr, priv->bulkout,
                         (uint8_t*)cbw, USBSTRG_CBW_SIZEOF);
   if (result == OK)
     {
       /* Receive the read capacity CBW IN response */
 
-      result = DRVR_TRANSFER(priv->drvr, &priv->bulkin,
+      result = DRVR_TRANSFER(priv->drvr, priv->bulkin,
                              priv->tdbuffer, SCSIRESP_READCAPACITY10_SIZEOF);
       if (result == OK)
         {
@@ -783,7 +785,7 @@ static inline int usbhost_readcapacity(FAR struct usbhost_state_s *priv)
 
           /* Receive the CSW */
 
-          result = DRVR_TRANSFER(priv->drvr, &priv->bulkin,
+          result = DRVR_TRANSFER(priv->drvr, priv->bulkin,
                                  priv->tdbuffer, USBSTRG_CSW_SIZEOF);
           if (result == OK)
             {
@@ -813,13 +815,13 @@ static inline int usbhost_inquiry(FAR struct usbhost_state_s *priv)
   /* Construct and send the CBW */
  
   usbhost_inquirycbw(cbw);
-  result = DRVR_TRANSFER(priv->drvr, &priv->bulkout,
+  result = DRVR_TRANSFER(priv->drvr, priv->bulkout,
                          (uint8_t*)cbw, USBSTRG_CBW_SIZEOF);
   if (result == OK)
     {
       /* Receive the CBW IN response */
 
-      result = DRVR_TRANSFER(priv->drvr, &priv->bulkin,
+      result = DRVR_TRANSFER(priv->drvr, priv->bulkin,
                              priv->tdbuffer, SCSIRESP_INQUIRY_SIZEOF);
       if (result == OK)
         {
@@ -829,7 +831,7 @@ static inline int usbhost_inquiry(FAR struct usbhost_state_s *priv)
 
           /* Receive the CSW */
 
-          result = DRVR_TRANSFER(priv->drvr, &priv->bulkin,
+          result = DRVR_TRANSFER(priv->drvr, priv->bulkin,
                                  priv->tdbuffer, USBSTRG_CSW_SIZEOF);
           if (result == OK)
             {
@@ -874,6 +876,18 @@ static void usbhost_destroy(FAR void *arg)
 
   usbhost_freedevno(priv);
 
+  /* Free the bulk endpoints */
+
+  if (priv->bulkout)
+    {
+      DRVR_EPFREE(priv->drvr, priv->bulkout);
+    }
+
+  if (priv->bulkin)
+    {
+      DRVR_EPFREE(priv->drvr, priv->bulkin);
+    }
+
   /* Free any transfer buffers */
 
   usbhost_tdfree(priv);
@@ -895,6 +909,198 @@ static void usbhost_destroy(FAR void *arg)
   usbhost_freeclass(priv);
 }
 
+/****************************************************************************
+ * 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 bindesc;
+  FAR struct usbhost_epdesc_s boutdesc;
+  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:
+          {
+            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;
+
+        /* Endpoint descriptor.  We expect two bulk endpoints, an IN and an OUT */
+        case USB_DESC_TYPE_ENDPOINT:
+          {
+            FAR struct usb_epdesc_s *epdesc = (FAR struct usb_epdesc_s *)configdesc;
+            DEBUGASSERT(remaining >= USB_SIZEOF_EPDESC);
+
+            /* Check for a bulk endpoint.  We only support the bulk-only
+             * protocol so I suppose anything else should really be an error.
+             */
+
+            if ((epdesc->attr & USB_EP_ATTR_XFERTYPE_MASK) == USB_EP_ATTR_XFER_BULK)
+              {
+                /* Yes.. it is a bulk endpoint.  IN or OUT? */
+
+                if (USB_ISEPOUT(epdesc->addr))
+                  {
+                    /* It is an OUT bulk endpoint.  There should be only one bulk OUT endpoint. */
+
+                    if ((found & USBHOST_BOUTFOUND) != 0)
+                      {
+                        /* Oops.. more than one interface.  We don't know what to do with this. */
+
+                        return -EINVAL;
+                      }
+                    found |= USBHOST_BOUTFOUND;
+
+                    /* Save the bulk OUT endpoint information */
+
+                    boutdesc.addr         = epdesc->addr & USB_EP_ADDR_NUMBER_MASK;
+                    boutdesc.in           = false;
+                    boutdesc.funcaddr     = funcaddr;
+                    boutdesc.mxpacketsize = usbhost_getle16(epdesc->mxpacketsize);
+                    uvdbg("Bulk OUT EP addr:%d mxpacketsize:%d\n",
+                          boutdesc.addr, boutdesc.mxpacketsize);
+                  }
+                else
+                  {
+                    /* It is an IN bulk endpoint.  There should be only one bulk IN endpoint. */
+
+                    if ((found & USBHOST_BINFOUND) != 0)
+                      {
+                        /* Oops.. more than one interface.  We don't know what to do with this. */
+
+                        return -EINVAL;
+                      }
+                    found |= USBHOST_BINFOUND;
+
+                    /* Save the bulk IN endpoint information */
+                    
+                    bindesc.addr        = epdesc->addr & USB_EP_ADDR_NUMBER_MASK;
+                    bindesc.in           = 1;
+                    bindesc.funcaddr     = funcaddr;
+                    bindesc.mxpacketsize = usbhost_getle16(epdesc->mxpacketsize);
+                    uvdbg("Bulk IN EP addr:%d mxpacketsize:%d\n",
+                          bindesc.addr, bindesc.mxpacketsize);
+                  }
+              }
+          }
+          break;
+
+        /* Other descriptors are just ignored for now */
+
+        default:
+          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? Hmmm..  I wonder..
+   * can we work read-only or write-only if only one bulk endpoint found?
+   */
+    
+  if (found != USBHOST_ALLFOUND)
+    {
+      ulldbg("ERROR: Found IF:%s BIN:%s BOUT:%s\n",
+             (found & USBHOST_IFFOUND) != 0  ? "YES" : "NO",
+             (found & USBHOST_BINFOUND) != 0 ? "YES" : "NO",
+             (found & USBHOST_BOUTFOUND) != 0 ? "YES" : "NO");
+      return -EINVAL;
+    }
+
+  /* We are good... Allocate the endpoints */
+
+  ret = DRVR_EPALLOC(priv->drvr, &boutdesc, &priv->bulkout);
+  if (ret != OK)
+    {
+      udbg("ERROR: Failed to allocated Bulk OUT endpoint\n");
+      return ret;
+    }
+
+  ret = DRVR_EPALLOC(priv->drvr, &bindesc, &priv->bulkin);
+  if (ret != OK)
+    {
+      udbg("ERROR: Failed to allocated Bulk IN endpoint\n");
+      (void)DRVR_EPFREE(priv->drvr, priv->bulkout);
+      return ret;
+    }
+
+  ullvdbg("Endpoints allocated\n");
+  return OK;
+}
+
 /****************************************************************************
  * Name: usbhost_initvolume
  *
@@ -908,29 +1114,28 @@ static void usbhost_destroy(FAR void *arg)
  *   connect() was called from an interrupt handler, on the worker thread.
  *
  * Input Parameters:
- *   arg - A reference to the class instance.
+ *   priv - A reference to the class instance.
  *
  * Returned Values:
  *   None
  *
  ****************************************************************************/
 
-static void usbhost_initvolume(FAR void *arg)
+static inline int usbhost_initvolume(FAR struct usbhost_state_s *priv)
 {
-  FAR struct usbhost_state_s *priv = (FAR struct usbhost_state_s *)arg;
   FAR struct usbstrg_csw_s *csw;
   unsigned int retries;
-  int result = OK;
+  int ret = OK;
 
   DEBUGASSERT(priv != NULL);
 
   /* Set aside a transfer buffer for exclusive use by the mass storage driver */
 
-  result = usbhost_tdalloc(priv);
-  if (result != OK)
+  ret = usbhost_tdalloc(priv);
+  if (ret != OK)
     {
       udbg("ERROR: Failed to allocate transfer buffer\n");
-      return;
+      return ret;
     }
 
   /* Increment the reference count.  This will prevent usbhost_destroy() from
@@ -943,18 +1148,18 @@ static void usbhost_initvolume(FAR void *arg)
   /* Request the maximum logical unit number */
 
   uvdbg("Get max LUN\n");
-  result = usbhost_maxlunreq(priv);
+  ret = usbhost_maxlunreq(priv);
 
   /* Wait for the unit to be ready */
 
-  for (retries = 0; retries < USBHOST_MAX_RETRIES && result == OK; retries++)
+  for (retries = 0; retries < USBHOST_MAX_RETRIES && ret == OK; retries++)
     {
       uvdbg("Test unit ready, retries=%d\n", retries);
 
       /* Send TESTUNITREADY to see the unit is ready */
       
-      result = usbhost_testunitready(priv);
-      if (result == OK)
+      ret = usbhost_testunitready(priv);
+      if (ret == OK)
         {
           /* Is the unit is ready */
 
@@ -972,7 +1177,7 @@ static void usbhost_initvolume(FAR void *arg)
            */
 
           uvdbg("Request sense\n");
-          result = usbhost_requestsense(priv);
+          ret = usbhost_requestsense(priv);
         }
     }
 
@@ -981,16 +1186,16 @@ static void usbhost_initvolume(FAR void *arg)
   if (retries >= USBHOST_MAX_RETRIES)
     {
       udbg("ERROR: Timeout!\n");
-      result = -ETIMEDOUT;
+      ret = -ETIMEDOUT;
     }
 
-  if (result == OK)
+  if (ret == OK)
     {
       /* Get the capacity of the volume */
 
       uvdbg("Read capacity\n");
-      result = usbhost_readcapacity(priv);
-      if (result == OK)
+      ret = usbhost_readcapacity(priv);
+      if (ret == OK)
         {
           /* Check the CSW for errors */
 
@@ -998,20 +1203,20 @@ static void usbhost_initvolume(FAR void *arg)
           if (csw->status != 0)
             {
               udbg("ERROR: CSW status error: %d\n", csw->status);
-              result = -ENODEV;
+              ret = -ENODEV;
             }
         }
     }
 
   /* Get information about the volume */
 
-  if (result == OK)
+  if (ret == OK)
     {
       /* Inquiry */
 
       uvdbg("Inquiry\n");
-      result = usbhost_inquiry(priv);
-      if (result == OK)
+      ret = usbhost_inquiry(priv);
+      if (ret == OK)
         {
           /* Check the CSW for errors */
 
@@ -1019,20 +1224,20 @@ static void usbhost_initvolume(FAR void *arg)
           if (csw->status != 0)
             {
               udbg("ERROR: CSW status error: %d\n", csw->status);
-              result = -ENODEV;
+              ret = -ENODEV;
             }
         }
     }
 
   /* Register the block driver */
 
-  if (result == OK)
+  if (ret == OK)
     {
       char devname[DEV_NAMELEN];
 
       uvdbg("Register block driver\n");
       usbhost_mkdevname(priv, devname);
-      result = register_blockdriver(devname, &g_bops, 0, priv);
+      ret = register_blockdriver(devname, &g_bops, 0, priv);
     }
 
   /* Check if we successfully initialized. We now have to be concerned
@@ -1040,7 +1245,7 @@ static void usbhost_initvolume(FAR void *arg)
    * driver has been registerd.
    */
 
-  if (result == OK)
+  if (ret == OK)
     {
       usbhost_takesem(&priv->exclsem);
       DEBUGASSERT(priv->crefs >= 2);
@@ -1057,7 +1262,7 @@ static void usbhost_initvolume(FAR void *arg)
            * destroyed when usb_destroy is called.
            */
   
-          result = -ENODEV;
+          ret = -ENODEV;
         }
       else
         {
@@ -1071,50 +1276,13 @@ static void usbhost_initvolume(FAR void *arg)
 
   /* Disconnect on any errors detected during volume initialization */
 
-  if (result != OK)
+  if (ret != OK)
     {
-      udbg("ERROR! Aborting: %d\n", result);
+      udbg("ERROR! Aborting: %d\n", ret);
       usbhost_destroy(priv);
     }
-}
 
-/****************************************************************************
- * Name: usbhost_work
- *
- * Description:
- *   Perform work, depending on context:  If we are executing from an
- *   interrupt handler, then defer the work to the worker thread.  Otherwise,
- *   just execute the work now.
- *
- * Input Parameters:
- *   priv - A reference to the class instance.
- *   worker - A reference to the worker function to be executed
- *
- * Returned Values:
- *   None
- *
- ****************************************************************************/
-
-static void usbhost_work(FAR struct usbhost_state_s *priv, worker_t worker)
-{
-  /* Are we in an interrupt handler? */
-
-  if (up_interrupt_context())
-    {
-      /* Yes.. do the work on the worker thread.  Higher level logic should
-       * prevent us from over-running the work structure.
-       */
-
-      uvdbg("Queuing work: worker %p->%p\n", priv->work.worker, worker);
-      DEBUGASSERT(priv->work.worker == NULL);
-      (void)work_queue(&priv->work, worker, priv, 0);
-    }
-  else
-    {
-      /* No.. do the work now */
-
-      worker(priv);
-    }
+  return ret;
 }
 
 /****************************************************************************
@@ -1474,9 +1642,7 @@ static FAR struct usbhost_class_s *usbhost_create(FAR struct usbhost_driver_s *d
  *   returned indicating the nature of the failure
  *
  * Assumptions:
- *   This function is probably called on the same thread that called the driver
- *   enumerate() method.  However, this function may also be called from an
- *   interrupt handler.
+ *   This function will *not* be called from an interrupt handler.
  *
  ****************************************************************************/
 
@@ -1485,151 +1651,31 @@ static int usbhost_connect(FAR struct usbhost_class_s *class,
                            uint8_t funcaddr)
 {
   FAR struct usbhost_state_s *priv = (FAR struct usbhost_state_s *)class;
-  FAR struct usb_cfgdesc_s *cfgdesc;
-  FAR struct usb_desc_s *desc;
-  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)
+  /* Parse the configuration descriptor to get the bulk I/O endpoints */
+
+  ret = usbhost_cfgdesc(priv, configdesc, desclen, funcaddr);
+  if (ret != OK)
     {
-      return -EINVAL;
+      udbg("usbhost_cfgdesc() failed: %d\n", ret);
     }
-
-  /* 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))
+  else
     {
-      /* What is the next descriptor? */
+      /* Now configure the LUNs and register the block driver(s) */
 
-      desc = (FAR struct usb_desc_s *)configdesc;
-      switch (desc->type)
+      ret = usbhost_initvolume(priv);
+      if (ret != OK)
         {
-        /* Interface descriptor. We really should get the number of endpoints
-         * from this descriptor too.
-         */
-
-        case USB_DESC_TYPE_INTERFACE:
-          {
-            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;
-
-        /* Endpoint descriptor.  We expect two bulk endpoints, an IN and an OUT */
-        case USB_DESC_TYPE_ENDPOINT:
-          {
-            FAR struct usb_epdesc_s *epdesc = (FAR struct usb_epdesc_s *)configdesc;
-            DEBUGASSERT(remaining >= USB_SIZEOF_EPDESC);
-
-            /* Check for a bulk endpoint.  We only support the bulk-only
-             * protocol so I suppose anything else should really be an error.
-             */
-
-            if ((epdesc->attr & USB_EP_ATTR_XFERTYPE_MASK) == USB_EP_ATTR_XFER_BULK)
-              {
-                /* Yes.. it is a bulk endpoint.  IN or OUT? */
-
-                if (USB_ISEPOUT(epdesc->addr))
-                  {
-                    /* It is an OUT bulk endpoint.  There should be only one bulk OUT endpoint. */
-
-                    if ((found & USBHOST_BOUTFOUND) != 0)
-                      {
-                        /* Oops.. more than one interface.  We don't know what to do with this. */
-
-                        return -EINVAL;
-                      }
-                    found |= USBHOST_BOUTFOUND;
-
-                    /* Save the bulk OUT endpoint information */
-
-                    priv->bulkout.addr         = epdesc->addr & USB_EP_ADDR_NUMBER_MASK;
-                    priv->bulkout.in           = 0;
-                    priv->bulkout.funcaddr     = funcaddr;
-                    priv->bulkout.mxpacketsize = usbhost_getle16(epdesc->mxpacketsize);
-                    uvdbg("Bulk OUT EP addr:%d mxpacketsize:%d\n",
-                          priv->bulkout.addr, priv->bulkout.mxpacketsize);
-                  }
-                else
-                  {
-                    /* It is an IN bulk endpoint.  There should be only one bulk IN endpoint. */
-
-                    if ((found & USBHOST_BINFOUND) != 0)
-                      {
-                        /* Oops.. more than one interface.  We don't know what to do with this. */
-
-                        return -EINVAL;
-                      }
-                    found |= USBHOST_BINFOUND;
-
-                    /* Save the bulk IN endpoint information */
-                    
-                    priv->bulkin.addr          = epdesc->addr & USB_EP_ADDR_NUMBER_MASK;
-                    priv->bulkin.in            = 1;
-                    priv->bulkin.funcaddr      = funcaddr;
-                    priv->bulkin.mxpacketsize  = usbhost_getle16(epdesc->mxpacketsize);
-                    uvdbg("Bulk IN EP addr:%d mxpacketsize:%d\n",
-                          priv->bulkin.addr, priv->bulkin.mxpacketsize);
-                  }
-              }
-          }
-          break;
-
-        /* Other descriptors are just ignored for now */
-
-        default:
-          break;
+          udbg("usbhost_initvolume() failed: %d\n", ret);
         }
-
-      /* Increment the address of the next descriptor */
- 
-      configdesc += desc->len;
-      remaining  -= desc->len;
-    }
-
-  /* Sanity checking... did we find all of things that we need? Hmmm..  I wonder..
-   * can we work read-only or write-only if only one bulk endpoint found?
-   */
-    
-  if (found != USBHOST_ALLFOUND)
-    {
-      ulldbg("ERROR: Found IF:%s BIN:%s BOUT:%s\n",
-             (found & USBHOST_IFFOUND) != 0  ? "YES" : "NO",
-             (found & USBHOST_BINFOUND) != 0 ? "YES" : "NO",
-             (found & USBHOST_BOUTFOUND) != 0 ? "YES" : "NO");
-      return -EINVAL;
     }
-
-  ullvdbg("Mass Storage device connected\n");
-
-  /* Now configure the LUNs and register the block driver(s) */
-
-  usbhost_work(priv, usbhost_initvolume);
-  return OK;
+ 
+  return ret;
 }
 
 /****************************************************************************
@@ -1677,10 +1723,27 @@ static int usbhost_disconnected(struct usbhost_class_s *class)
   ullvdbg("crefs: %d\n", priv->crefs);
   if (priv->crefs == 1)
     {
-      /* Destroy the class instance */
+      /* Destroy the class instance.  If we are executing from an interrupt
+       * handler, then defer the destruction to the worker thread.
+       * Otherwise, destroy the instance now.
+       */
+
+      if (up_interrupt_context())
+        {
+          /* Destroy the instance on the worker thread. */
 
-      usbhost_work(priv, usbhost_destroy);
+          uvdbg("Queuing destruction: worker %p->%p\n", priv->work.worker, usbhost_destroy);
+          DEBUGASSERT(priv->work.worker == NULL);
+          (void)work_queue(&priv->work, usbhost_destroy, priv, 0);
+       }
+      else
+        {
+          /* Do the work now */
+
+          usbhost_destroy(priv);
+        }
     }
+
   irqrestore(flags);  
   return OK;
 }
@@ -1845,19 +1908,19 @@ static ssize_t usbhost_read(FAR struct inode *inode, unsigned char *buffer,
           /* Construct and send the CBW */
  
           usbhost_readcbw(startsector, priv->blocksize, nsectors, cbw);
-          result = DRVR_TRANSFER(priv->drvr, &priv->bulkout,
+          result = DRVR_TRANSFER(priv->drvr, priv->bulkout,
                                  (uint8_t*)cbw, USBSTRG_CBW_SIZEOF);
           if (result == OK)
             {
               /* Receive the user data */
 
-              result = DRVR_TRANSFER(priv->drvr, &priv->bulkin,
+              result = DRVR_TRANSFER(priv->drvr, priv->bulkin,
                                      buffer, priv->blocksize * nsectors);
               if (result == OK)
                 {
                   /* Receive the CSW */
 
-                  result = DRVR_TRANSFER(priv->drvr, &priv->bulkin,
+                  result = DRVR_TRANSFER(priv->drvr, priv->bulkin,
                                          priv->tdbuffer, USBSTRG_CSW_SIZEOF);
                   if (result == OK)
                     {
@@ -1937,19 +2000,19 @@ static ssize_t usbhost_write(FAR struct inode *inode, const unsigned char *buffe
           /* Construct and send the CBW */
  
           usbhost_writecbw(startsector, priv->blocksize, nsectors, cbw);
-          result = DRVR_TRANSFER(priv->drvr, &priv->bulkout,
+          result = DRVR_TRANSFER(priv->drvr, priv->bulkout,
                                  (uint8_t*)cbw, USBSTRG_CBW_SIZEOF);
           if (result == OK)
             {
               /* Send the user data */
 
-              result = DRVR_TRANSFER(priv->drvr, &priv->bulkout,
+              result = DRVR_TRANSFER(priv->drvr, priv->bulkout,
                                      (uint8_t*)buffer, priv->blocksize * nsectors);
               if (result == OK)
                 {
                   /* Receive the CSW */
 
-                  result = DRVR_TRANSFER(priv->drvr, &priv->bulkin,
+                  result = DRVR_TRANSFER(priv->drvr, priv->bulkin,
                                          priv->tdbuffer, USBSTRG_CSW_SIZEOF);
                   if (result == OK)
                     {
diff --git a/nuttx/include/nuttx/usb/usbhost.h b/nuttx/include/nuttx/usb/usbhost.h
index a83048f68..e69f1814a 100644
--- a/nuttx/include/nuttx/usb/usbhost.h
+++ b/nuttx/include/nuttx/usb/usbhost.h
@@ -139,7 +139,7 @@
  *   returned indicating the nature of the failure
  *
  * Assumptions:
- *   This function may be called from an interrupt handler.
+ *   This function will *not* be called from an interrupt handler.
  *
  ************************************************************************************/
 
@@ -225,6 +225,52 @@
 
 #define DRVR_EP0CONFIGURE(drvr,funcaddr,mps) ((drvr)->ep0configure(drvr,funcaddr,mps))
 
+/************************************************************************************
+ * Name: DRVR_EPALLOC
+ *
+ * Description:
+ *   Allocate and configure one endpoint.
+ *
+ * Input Parameters:
+ *   drvr - The USB host driver instance obtained as a parameter from the call to
+ *      the class create() method.
+ *   epdesc - Describes the endpoint to be allocated.
+ *   ep - A memory location provided by the caller in which to receive the
+ *      allocated endpoint desciptor.
+ *
+ * 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_EPALLOC(drvr,epdesc,ep) ((drvr)->epalloc(drvr,epdesc,ep))
+
+/************************************************************************************
+ * Name: DRVR_EPFREE
+ *
+ * Description:
+ *   Free and endpoint previously allocated by DRVR_EPALLOC.
+ *
+ * Input Parameters:
+ *   drvr - The USB host driver instance obtained as a parameter from the call to
+ *      the class create() method.
+ *   ep - The endpint to be freed.
+ *
+ * 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_EPFREE(drvr,ep) ((drvr)->epfree(drvr,ep))
+
 /************************************************************************************
  * Name: DRVR_ALLOC
  *
@@ -441,11 +487,30 @@ struct usbhost_class_s
   int (*disconnected)(FAR struct usbhost_class_s *class);
 };
 
+/* This structure describes one endpoint.  It is used as an input to the
+ * allocep() method.
+ */
+
+struct usbhost_epdesc_s
+{
+  uint8_t  addr;         /* Endpoint address */
+  bool     in;           /* Direction: true->IN */
+  uint8_t  funcaddr;     /* USB address of function containing endpoint */
+  uint16_t mxpacketsize; /* Max packetsize */
+};
+
+/* This type represents one endpoint configured by the allocep() method.
+ * The actual form is know only internally to the USB host controller
+ * (for example, for an OHCI driver, this would probably be a pointer
+ * to an endpoint descriptor).
+ */
+
+typedef FAR void *usbhost_ep_t;
+
 /* struct usbhost_driver_s provides access to the USB host driver from the
  * USB host class implementation.
  */
 
-struct usbhost_epdesc_s;
 struct usbhost_driver_s
 {
   /* Wait for a device to connect or disconnect. */
@@ -472,6 +537,12 @@ struct usbhost_driver_s
   int (*ep0configure)(FAR struct usbhost_driver_s *drvr, uint8_t funcaddr,
                       uint16_t maxpacketsize);
 
+  /* Allocate and configure an endpoint. */
+
+  int (*epalloc)(FAR struct usbhost_driver_s *drvr,
+                const FAR struct usbhost_epdesc_s *epdesc, usbhost_ep_t *ep);
+  int (*epfree)(FAR struct usbhost_driver_s *drvr, usbhost_ep_t ep);
+
   /* 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
@@ -508,8 +579,7 @@ struct usbhost_driver_s
    * transfer has completed.
    */
 
-  int (*transfer)(FAR struct usbhost_driver_s *drvr,
-                  FAR struct usbhost_epdesc_s *ep,
+  int (*transfer)(FAR struct usbhost_driver_s *drvr, usbhost_ep_t ep,
                   FAR uint8_t *buffer, size_t buflen);
 
   /* Called by the class when an error occurs and driver has been disconnected.
@@ -521,18 +591,6 @@ struct usbhost_driver_s
   void (*disconnect)(FAR struct usbhost_driver_s *drvr);
 };
 
-/* This structure describes one endpoint */
-
-struct usbhost_epdesc_s
-{
-  uint8_t  addr     : 4; /* Endpoint address */
-  uint8_t  pad      : 3;
-  uint8_t  in       : 1; /* Direction: 1->IN */
-  uint8_t  funcaddr : 7; /* USB address of function containing endpoint */
-  uint8_t  toggle   : 1; /* Last toggle (modified by the driver) */
-  uint16_t mxpacketsize; /* Max packetsize */
-};
-
 /************************************************************************************
  * Public Data
  ************************************************************************************/
-- 
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