make vendor driver more flexible

- skip additional custom descriptor between interface and endpoints
- can have up to 2 bulk endpoint ( 1 in & 1 out)

src/class/vendor/vendor_device.c

@@ -175,12 +175,12 @@ void vendord_reset(uint8_t rhport)
   }
 }
 
-uint16_t vendord_open(uint8_t rhport, tusb_desc_interface_t const * itf_desc, uint16_t max_len)
+uint16_t vendord_open(uint8_t rhport, tusb_desc_interface_t const * desc_itf, uint16_t max_len)
 {
-  TU_VERIFY(TUSB_CLASS_VENDOR_SPECIFIC == itf_desc->bInterfaceClass, 0);
+  TU_VERIFY(TUSB_CLASS_VENDOR_SPECIFIC == desc_itf->bInterfaceClass, 0);
 
-  uint16_t const drv_len = sizeof(tusb_desc_interface_t) + itf_desc->bNumEndpoints*sizeof(tusb_desc_endpoint_t);
-  TU_VERIFY(max_len >= drv_len, 0);
+  uint16_t drv_len = tu_desc_len(desc_itf);
+  uint8_t const * p_desc = tu_desc_next(desc_itf);
 
   // Find available interface
   vendord_interface_t* p_vendor = NULL;
@@ -194,21 +194,29 @@ uint16_t vendord_open(uint8_t rhport, tusb_desc_interface_t const * itf_desc, ui
   }
   TU_VERIFY(p_vendor, 0);
 
-  // Open endpoint pair with usbd helper
-  TU_ASSERT(usbd_open_edpt_pair(rhport, tu_desc_next(itf_desc), 2, TUSB_XFER_BULK, &p_vendor->ep_out, &p_vendor->ep_in), 0);
+  p_vendor->itf_num = desc_itf->bInterfaceNumber;
+  if (desc_itf->bNumEndpoints)
+  {
+    // skip non-endpoint descriptors
+    while ( (TUSB_DESC_ENDPOINT != tu_desc_type(p_desc)) && (drv_len <= max_len) )
+    {
+      drv_len += tu_desc_len(p_desc);
+      p_desc   = tu_desc_next(p_desc);
+    }
 
-  p_vendor->itf_num = itf_desc->bInterfaceNumber;
+    // Open endpoint pair with usbd helper
+    TU_ASSERT(usbd_open_edpt_pair(rhport, p_desc, desc_itf->bNumEndpoints, TUSB_XFER_BULK, &p_vendor->ep_out, &p_vendor->ep_in), 0);
 
-  // Prepare for incoming data
-  if ( !usbd_edpt_xfer(rhport, p_vendor->ep_out, p_vendor->epout_buf, sizeof(p_vendor->epout_buf)) )
-  {
-    TU_LOG_FAILED();
-    TU_BREAKPOINT();
-  }
+    // Prepare for incoming data
+    if ( p_vendor->ep_out )
+    {
+      TU_ASSERT(usbd_edpt_xfer(rhport, p_vendor->ep_out, p_vendor->epout_buf, sizeof(p_vendor->epout_buf)), 0);
+    }
 
-  maybe_transmit(p_vendor);
+    if ( p_vendor->ep_in ) maybe_transmit(p_vendor);
+  }
 
-  return drv_len;
+  return (uint16_t) true;
 }
 
 bool vendord_xfer_cb(uint8_t rhport, uint8_t ep_addr, xfer_result_t result, uint32_t xferred_bytes)

src/device/usbd.c

@@ -922,7 +922,7 @@ static bool process_set_config(uint8_t rhport, uint8_t cfg_num)
 #endif
 
     uint16_t const drv_len = tu_desc_get_interface_total_len(desc_itf, assoc_itf_count, desc_end-p_desc);
-    TU_ASSERT(drv_len);
+    TU_ASSERT(drv_len >= sizeof(tusb_desc_interface_t));
 
     // Find driver for this interface
     uint8_t drv_id;

src/host/usbh.c

@@ -1016,7 +1016,7 @@ static bool parse_configuration_descriptor(uint8_t dev_addr, tusb_desc_configura
 #endif
 
     uint16_t const drv_len = tu_desc_get_interface_total_len(desc_itf, assoc_itf_count, desc_end-p_desc);
-    TU_ASSERT(drv_len);
+    TU_ASSERT(drv_len >= sizeof(tusb_desc_interface_t));
 
     if (desc_itf->bInterfaceClass == TUSB_CLASS_HUB && dev->hub_addr != 0)
     {