usb: Support for class specific endpoint descriptors.

Extends struct usb_endpoint_descriptor to make it possible to provide
the USB host with class-specific extensions to endpoint descriptors.

The approach taken, based on extra and extralen and removing the sizeof()
from USB_DT_ENDPOINT_SIZE, is identical to the approach used to add
class-specific extensions to interface descriptors. All libopencm3-examples
use the USB_DT_ENDPOINT_SIZE (rather than directly using sizeof) so there
should be no compatibility problems resulting from this change.

1 files changed, 9 insertions, 0 deletions

diff --git a/lib/usb/usb_standard.c b/lib/usb/usb_standard.c
index 42458722..bc4710ff 100644
--- a/lib/usb/usb_standard.c
+++ b/lib/usb/usb_standard.c
@@ -110,6 +110,15 @@ static uint16_t build_config_descriptor(usbd_device *usbd_dev,
 				len -= count;
 				total += count;
 				totallen += ep->bLength;
+				/* Copy extra bytes (class specific). */
+				if (ep->extra) {
+					memcpy(buf, ep->extra,
+					       count = MIN(len, ep->extralen));
+					buf += count;
+					len -= count;
+					total += count;
+					totallen += ep->extralen;
+				}
 			}
 		}
 	}