From b32ec6b864826d0f1bcf9b6e7b7c20f3540d78a4 Mon Sep 17 00:00:00 2001
From: Koen Zandberg <koen@bergzand.net>
Date: Wed, 23 Oct 2019 09:58:08 +0200
Subject: [PATCH 1/2] usbus: add find_endpoint function for interfaces

---
 sys/include/usb/usbus.h | 18 ++++++++++++++++++
 sys/usb/usbus/usbus.c   | 12 ++++++++++++
 2 files changed, 30 insertions(+)

diff --git a/sys/include/usb/usbus.h b/sys/include/usb/usbus.h
index 090f969d9c..9ce0563ccc 100644
--- a/sys/include/usb/usbus.h
+++ b/sys/include/usb/usbus.h
@@ -427,6 +427,24 @@ uint16_t usbus_add_string_descriptor(usbus_t *usbus, usbus_string_t *desc,
  */
 uint16_t usbus_add_interface(usbus_t *usbus, usbus_interface_t *iface);
 
+/**
+ * @brief Find an endpoint from an interface based on the endpoint properties
+ *
+ * This iterates over the endpoints in an interface and will return the first
+ * endpoint from the interface matching the @p type and @p dir. It will return
+ * NULL when no matching endpoint is found.
+ *
+ * @param[in] interface interface to look in
+ * @param[in] type      endpoint type to match
+ * @param[in] dir       endpoint direction to match
+ *
+ * @return              ptr to the first matching endpoint
+ * @return              NULL when no endpoint is found
+ */
+usbus_endpoint_t *usbus_interface_find_endpoint(usbus_interface_t *interface,
+                                                usb_ep_type_t type,
+                                                usb_ep_dir_t dir);
+
 /**
  * @brief Add an endpoint to the specified interface
  *
diff --git a/sys/usb/usbus/usbus.c b/sys/usb/usbus/usbus.c
index a39b9d2ca3..8006f81252 100644
--- a/sys/usb/usbus/usbus.c
+++ b/sys/usb/usbus/usbus.c
@@ -127,6 +127,18 @@ void usbus_register_event_handler(usbus_t *usbus, usbus_handler_t *handler)
     *last = handler;
 }
 
+usbus_endpoint_t *usbus_interface_find_endpoint(usbus_interface_t *interface,
+                                                usb_ep_type_t type,
+                                                usb_ep_dir_t dir)
+{
+    for (usbus_endpoint_t *uep = interface->ep; uep; uep = uep->next) {
+        if (uep->ep->type == type && uep->ep->dir == dir) {
+            return uep;
+        }
+    }
+    return NULL;
+}
+
 usbus_endpoint_t *usbus_add_endpoint(usbus_t *usbus, usbus_interface_t *iface,
                                      usb_ep_type_t type, usb_ep_dir_t dir,
                                      size_t len)

From 1d7032a257f5855c52c7b1aa043c3b863717caca Mon Sep 17 00:00:00 2001
From: Koen Zandberg <koen@bergzand.net>
Date: Mon, 21 Oct 2019 20:35:47 +0200
Subject: [PATCH 2/2] cdcacm: Activate data out endpoint on DTE present signal

---
 sys/usb/usbus/cdc/acm/cdc_acm.c | 7 ++++++-
 1 file changed, 6 insertions(+), 1 deletion(-)

diff --git a/sys/usb/usbus/cdc/acm/cdc_acm.c b/sys/usb/usbus/cdc/acm/cdc_acm.c
index 3f9fb3fa42..73039ea6b3 100644
--- a/sys/usb/usbus/cdc/acm/cdc_acm.c
+++ b/sys/usb/usbus/cdc/acm/cdc_acm.c
@@ -213,12 +213,13 @@ static void _init(usbus_t *usbus, usbus_handler_t *handler)
                             USBUS_CDC_ACM_BULK_EP_SIZE);
     ep->interval = 0; /* Interval is not used with bulk endpoints */
     usbus_enable_endpoint(ep);
+    /* Store the endpoint reference to activate it
+     * when DTE present is signalled by the host */
     ep = usbus_add_endpoint(usbus, &cdcacm->iface_data,
                             USB_EP_TYPE_BULK, USB_EP_DIR_OUT,
                             USBUS_CDC_ACM_BULK_EP_SIZE);
     ep->interval = 0; /* Interval is not used with bulk endpoints */
     usbus_enable_endpoint(ep);
-    usbdev_ep_ready(ep->ep, 0);
 
     /* Add interfaces to the stack */
     usbus_add_interface(usbus, &cdcacm->iface_ctrl);
@@ -271,6 +272,10 @@ static int _control_handler(usbus_t *usbus, usbus_handler_t *handler,
             if (setup->value & USB_CDC_ACM_CONTROL_LINE_DTE) {
                 DEBUG("CDC ACM: DTE enabled on interface %u\n", setup->index);
                 cdcacm->state = USBUS_CDC_ACM_LINE_STATE_DTE;
+                usbus_endpoint_t *data_out = usbus_interface_find_endpoint(
+                        &cdcacm->iface_data, USB_EP_TYPE_BULK, USB_EP_DIR_OUT);
+                assert(data_out);
+                usbdev_ep_ready(data_out->ep, 0);
                 usbus_cdc_acm_flush(cdcacm);
             }
             else {