diff --git a/src/class/cdc/cdc_host.c b/src/class/cdc/cdc_host.c
index facf86d5..dbe5341e 100644
--- a/src/class/cdc/cdc_host.c
+++ b/src/class/cdc/cdc_host.c
@@ -29,6 +29,8 @@
 #if (TUSB_OPT_HOST_ENABLED && CFG_TUH_CDC)
 
 #include "host/usbh.h"
+#include "host/usbh_classdriver.h"
+
 #include "cdc_host.h"
 
 //--------------------------------------------------------------------+
diff --git a/src/class/hid/hid_host.c b/src/class/hid/hid_host.c
index 83f3f303..ec50f55f 100644
--- a/src/class/hid/hid_host.c
+++ b/src/class/hid/hid_host.c
@@ -29,6 +29,8 @@
 #if (TUSB_OPT_HOST_ENABLED && CFG_TUH_HID)
 
 #include "host/usbh.h"
+#include "host/usbh_classdriver.h"
+
 #include "hid_host.h"
 
 //--------------------------------------------------------------------+
diff --git a/src/class/msc/msc_host.c b/src/class/msc/msc_host.c
index 205f0fd2..176403e8 100644
--- a/src/class/msc/msc_host.c
+++ b/src/class/msc/msc_host.c
@@ -29,6 +29,8 @@
 #if TUSB_OPT_HOST_ENABLED & CFG_TUH_MSC
 
 #include "host/usbh.h"
+#include "host/usbh_classdriver.h"
+
 #include "msc_host.h"
 
 //--------------------------------------------------------------------+
diff --git a/src/device/usbd_pvt.h b/src/device/usbd_pvt.h
index 65fdadf5..b8d34d7b 100644
--- a/src/device/usbd_pvt.h
+++ b/src/device/usbd_pvt.h
@@ -34,7 +34,7 @@
 #endif
 
 //--------------------------------------------------------------------+
-// Class Drivers
+// Class Driver API
 //--------------------------------------------------------------------+
 
 typedef struct
diff --git a/src/host/hub.c b/src/host/hub.c
index f921027c..b2761184 100644
--- a/src/host/hub.c
+++ b/src/host/hub.c
@@ -29,6 +29,7 @@
 #if (TUSB_OPT_HOST_ENABLED && CFG_TUH_HUB)
 
 #include "usbh.h"
+#include "usbh_classdriver.h"
 #include "hub.h"
 
 //--------------------------------------------------------------------+
diff --git a/src/host/usbh.c b/src/host/usbh.c
index ca065340..ff66d5af 100644
--- a/src/host/usbh.c
+++ b/src/host/usbh.c
@@ -24,7 +24,7 @@
  * This file is part of the TinyUSB stack.
  */
 
-#include "common/tusb_common.h"
+#include "tusb_option.h"
 
 #if TUSB_OPT_HOST_ENABLED
 
@@ -32,10 +32,9 @@
 #define CFG_TUH_TASK_QUEUE_SZ   16
 #endif
 
-//--------------------------------------------------------------------+
-// INCLUDE
-//--------------------------------------------------------------------+
 #include "tusb.h"
+#include "host/usbh.h"
+#include "host/usbh_classdriver.h"
 #include "hub.h"
 #include "usbh_hcd.h"
 
diff --git a/src/host/usbh.h b/src/host/usbh.h
index a9790b48..edc9e080 100644
--- a/src/host/usbh.h
+++ b/src/host/usbh.h
@@ -40,27 +40,6 @@
 //--------------------------------------------------------------------+
 // MACRO CONSTANT TYPEDEF
 //--------------------------------------------------------------------+
-typedef enum tusb_interface_status_{
-  TUSB_INTERFACE_STATUS_READY = 0,
-  TUSB_INTERFACE_STATUS_BUSY,
-  TUSB_INTERFACE_STATUS_COMPLETE,
-  TUSB_INTERFACE_STATUS_ERROR,
-  TUSB_INTERFACE_STATUS_INVALID_PARA
-} tusb_interface_status_t;
-
-typedef struct {
-  #if CFG_TUSB_DEBUG >= 2
-  char const* name;
-  #endif
-
-  uint8_t class_code;
-
-  void (* const init       )(void);
-  bool (* const open       )(uint8_t rhport, uint8_t dev_addr, tusb_desc_interface_t const * itf_desc, uint16_t* outlen);
-  bool (* const set_config )(uint8_t dev_addr, uint8_t itf_num);
-  bool (* const xfer_cb    )(uint8_t dev_addr, uint8_t ep_addr, xfer_result_t result, uint32_t xferred_bytes);
-  void (* const close      )(uint8_t dev_addr);
-} usbh_class_driver_t;
 
 typedef bool (*tuh_control_complete_cb_t)(uint8_t dev_addr, tusb_control_request_t const * request, xfer_result_t result);
 
@@ -101,30 +80,12 @@ bool tuh_control_xfer (uint8_t dev_addr, tusb_control_request_t const* request,
 //--------------------------------------------------------------------+
 //TU_ATTR_WEAK uint8_t tuh_attach_cb (tusb_desc_device_t const *desc_device);
 
-/** Callback invoked when device is mounted (configured) */
+// Invoked when device is mounted (configured)
 TU_ATTR_WEAK void tuh_mount_cb (uint8_t dev_addr);
 
-/** Callback invoked when device is unmounted (bus reset/unplugged) */
+/// Invoked when device is unmounted (bus reset/unplugged)
 TU_ATTR_WEAK void tuh_umount_cb(uint8_t dev_addr);
 
-//--------------------------------------------------------------------+
-// CLASS-USBH & INTERNAL API
-// TODO move to usbh_pvt.h
-//--------------------------------------------------------------------+
-
-bool usbh_edpt_open(uint8_t rhport, uint8_t dev_addr, tusb_desc_endpoint_t const * ep_desc);
-bool usbh_edpt_xfer(uint8_t dev_addr, uint8_t ep_addr, uint8_t * buffer, uint16_t total_bytes);
-
-// Claim an endpoint before submitting a transfer.
-// If caller does not make any transfer, it must release endpoint for others.
-bool usbh_edpt_claim(uint8_t dev_addr, uint8_t ep_addr);
-
-void usbh_driver_set_config_complete(uint8_t dev_addr, uint8_t itf_num);
-
-uint8_t usbh_get_rhport(uint8_t dev_addr);
-
-uint8_t* usbh_get_enum_buf(void);
-
 #ifdef __cplusplus
  }
 #endif
diff --git a/src/host/usbh_classdriver.h b/src/host/usbh_classdriver.h
new file mode 100644
index 00000000..2b152385
--- /dev/null
+++ b/src/host/usbh_classdriver.h
@@ -0,0 +1,76 @@
+/*
+ * The MIT License (MIT)
+ *
+ * Copyright (c) 2021, Ha Thach (tinyusb.org)
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+ * THE SOFTWARE.
+ *
+ * This file is part of the TinyUSB stack.
+ */
+
+#ifndef _TUSB_USBH_CLASSDRIVER_H_
+#define _TUSB_USBH_CLASSDRIVER_H_
+
+#include "osal/osal.h"
+#include "common/tusb_fifo.h"
+
+#ifdef __cplusplus
+ extern "C" {
+#endif
+
+//--------------------------------------------------------------------+
+// Class Driver API
+//--------------------------------------------------------------------+
+
+typedef struct {
+  #if CFG_TUSB_DEBUG >= 2
+  char const* name;
+  #endif
+
+  uint8_t class_code;
+
+  void (* const init       )(void);
+  bool (* const open       )(uint8_t rhport, uint8_t dev_addr, tusb_desc_interface_t const * itf_desc, uint16_t* outlen);
+  bool (* const set_config )(uint8_t dev_addr, uint8_t itf_num);
+  bool (* const xfer_cb    )(uint8_t dev_addr, uint8_t ep_addr, xfer_result_t result, uint32_t xferred_bytes);
+  void (* const close      )(uint8_t dev_addr);
+} usbh_class_driver_t;
+
+//--------------------------------------------------------------------+
+// USBH Endpoint API
+//--------------------------------------------------------------------+
+
+bool usbh_edpt_open(uint8_t rhport, uint8_t dev_addr, tusb_desc_endpoint_t const * ep_desc);
+bool usbh_edpt_xfer(uint8_t dev_addr, uint8_t ep_addr, uint8_t * buffer, uint16_t total_bytes);
+
+// Claim an endpoint before submitting a transfer.
+// If caller does not make any transfer, it must release endpoint for others.
+bool usbh_edpt_claim(uint8_t dev_addr, uint8_t ep_addr);
+
+void usbh_driver_set_config_complete(uint8_t dev_addr, uint8_t itf_num);
+
+uint8_t usbh_get_rhport(uint8_t dev_addr);
+
+uint8_t* usbh_get_enum_buf(void);
+
+#ifdef __cplusplus
+ }
+#endif
+
+#endif
diff --git a/src/host/usbh_hcd.h b/src/host/usbh_hcd.h
index abc7fd25..b3856d6b 100644
--- a/src/host/usbh_hcd.h
+++ b/src/host/usbh_hcd.h
@@ -97,12 +97,6 @@ typedef struct {
 
 extern usbh_device_t _usbh_devices[CFG_TUSB_HOST_DEVICE_MAX+1]; // including zero-address
 
-//--------------------------------------------------------------------+
-// callback from HCD ISR
-//--------------------------------------------------------------------+
-
-
-
 #ifdef __cplusplus
  }
 #endif