From 13b4f8de2cb2354e6a3a5cddf4c88885c272d5a1 Mon Sep 17 00:00:00 2001
From: Koen Zandberg <koen@bergzand.net>
Date: Sun, 31 Oct 2021 21:16:52 +0100
Subject: [PATCH] usbus: Implement endpoint halt condition.

Instead of directly stalling an endpoint, handlers should enable the
halt condition on an usbus endpoint to signal error condition.
This can then be cleared via a CLEAR FEATURE request from the host.
---
 sys/include/usb/usbus.h | 17 +++++++++++++++++
 sys/usb/usbus/usbus.c   | 29 +++++++++++++++++++++++++++++
 2 files changed, 46 insertions(+)

diff --git a/sys/include/usb/usbus.h b/sys/include/usb/usbus.h
index 3a46575012..ad0bb06b81 100644
--- a/sys/include/usb/usbus.h
+++ b/sys/include/usb/usbus.h
@@ -327,6 +327,7 @@ typedef struct usbus_endpoint {
     uint8_t interval;               /**< Poll interval for interrupt endpoints */
     bool active;                    /**< If the endpoint should be activated after
                                          reset */
+    bool halted;                    /**< Endpoint is halted */
 } usbus_endpoint_t;
 
 /**
@@ -676,6 +677,22 @@ void usbus_urb_submit(usbus_t *usbus, usbus_endpoint_t *endpoint, usbus_urb_t *u
  */
 int usbus_urb_cancel(usbus_t *usbus, usbus_endpoint_t *endpoint, usbus_urb_t *urb);
 
+/**
+ * @brief Set the halt condition on an endpoint.
+ *
+ * The endpoint will respond with stall to all packets and must explicitly be
+ * cleared by the host by clearing the halt condition or switching interfaces
+ */
+void usbus_endpoint_halt(usbus_endpoint_t *ep);
+
+/**
+ * @brief Clear the halt condition on an endpoint
+ *
+ * @note Must only be used when the endpoint is halted and when the host issues
+ * a SetInterface request on the interface containing the endpoint
+ */
+void usbus_endpoint_clear_halt(usbus_endpoint_t *ep);
+
 /**
  * @brief Enable an endpoint
  *
diff --git a/sys/usb/usbus/usbus.c b/sys/usb/usbus/usbus.c
index abba08e809..77bdf906c3 100644
--- a/sys/usb/usbus/usbus.c
+++ b/sys/usb/usbus/usbus.c
@@ -470,6 +470,34 @@ static void *_usbus_thread(void *args)
     return NULL;
 }
 
+void usbus_endpoint_halt(usbus_endpoint_t *ep)
+{
+    assert(ep->ep->num != 0); /* Not valid for endpoint 0 */
+    DEBUG("Endpoint %u halted\n", ep->ep->num);
+    ep->halted = 1;
+    usbdev_ep_stall(ep->ep, true);
+}
+
+void usbus_endpoint_clear_halt(usbus_endpoint_t *ep)
+{
+    assert(ep->ep->num != 0); /* Not valid for endpoint 0 */
+    DEBUG("Endpoint %u unhalted\n", ep->ep->num);
+    ep->halted = 0;
+    usbdev_ep_stall(ep->ep, false);
+}
+
+/**
+ * @brief Reset the halted status on USB reset condition
+ */
+static void _usbus_endpoint_reset_halt(usbus_t *usbus)
+{
+    /* Clear halted state. No need to notify usbdev, USB reset already resets those */
+    for (size_t i = 0; i < USBDEV_NUM_ENDPOINTS; i++) {
+        usbus->ep_out[i].halted = 0;
+        usbus->ep_in[i].halted = 0;
+    }
+}
+
 /* USB event callback */
 static void _event_cb(usbdev_t *usbdev, usbdev_event_t event)
 {
@@ -487,6 +515,7 @@ static void _event_cb(usbdev_t *usbdev, usbdev_event_t event)
                 usbus->addr = 0;
                 usbdev_set(usbus->dev, USBOPT_ADDRESS, &usbus->addr,
                            sizeof(uint8_t));
+                _usbus_endpoint_reset_halt(usbus);
                 flag = USBUS_HANDLER_FLAG_RESET;
                 msg = USBUS_EVENT_USB_RESET;
                 DEBUG("usbus: USB reset detected\n");