usb fix

zephcore/adapters/usb/ZephyrCompanionUSB.cpp

@@ -100,9 +100,16 @@ static const struct companion_link_cbs *s_link;
 K_MSGQ_DEFINE(usb_recv_queue, sizeof(struct frame), USB_RECV_QUEUE_DEPTH, 4);
 
 /* A session starts on the first traffic after open (a binary frame or a CLI
- * line) and ends when the host drops DTR. */
+ * line) and ends when the host drops DTR or goes away without one (VBUS loss,
+ * bus reset). */
 static bool usb_session_active;
 
+/* The session can carry frames: it is open and the bus is not suspended (host
+ * asleep with the port open). Main hears each edge as a connect or a
+ * disconnect, so a suspended session is not a client: nothing is queued for
+ * it, and it does not hold up the last-client cleanup. */
+static bool usb_link_up;
+
 /* CLI text line callback — fired when a complete line arrives in text mode. */
 static void (*s_cli_line_cb)(const char *line);
 static char usb_text_line[USB_TEXT_LINE_MAX];
@@ -189,6 +196,31 @@ static void usb_uart_isr(const struct device *dev, void *user_data)
 	}
 }
 
+/* Recompute usb_link_up and tell main about an edge. Arduino shows "connected"
+ * for serial transports too, so a text session raises the edges as well. */
+static void usb_link_update(void)
+{
+	bool up = usb_session_active;
+
+#if COMPANION_HAS_DTR
+	up = up && !zephcore_usbd_is_suspended();
+#endif
+	if (up == usb_link_up) {
+		return;
+	}
+	usb_link_up = up;
+	if (!s_link) {
+		return;
+	}
+	if (up) {
+		if (s_link->on_connected) {
+			s_link->on_connected();
+		}
+	} else if (s_link->on_disconnected) {
+		s_link->on_disconnected();
+	}
+}
+
 /* Start a session on its first inbound traffic — a binary frame or a complete
  * CLI line. The official client opens with CMD_DEVICE_QUERY (0x16), not
  * CMD_APP_START, so any first traffic starts it. Other transports (BLE, WiFi)
@@ -202,10 +234,7 @@ static void usb_session_begin(uint8_t log_tag, bool is_text)
 	usb_session_is_text = is_text;
 	LOG_INF("usb_rx: first traffic 0x%02x, session started (%s)", log_tag,
 		is_text ? "text" : "binary");
-	/* Arduino shows "connected" for serial transports too */
-	if (s_link && s_link->on_connected) {
-		s_link->on_connected();
-	}
+	usb_link_update();
 }
 
 /* USB RX work - parses V3 frames from ring buffer */
@@ -347,7 +376,8 @@ static void usb_rx_work_fn(struct k_work *work)
 
 #if COMPANION_HAS_DTR
 /* DTR-transition callback from the shared ZephyrUSBCDC module.
- * On drop: host closed the port → reset parser, hand control back to BLE.
+ * On drop (the host closed the port, or went away: VBUS loss, bus reset):
+ * reset the parser and end the session.
  * CDC-only — a plain-UART backend has no DTR and never registers this. */
 static void on_dtr_change(bool dtr_active)
 {
@@ -355,7 +385,6 @@ static void on_dtr_change(bool dtr_active)
 		return;
 	}
 	LOG_INF("usb_dtr: DTR dropped, USB disconnected");
-	bool was_active = usb_session_active;
 
 	usb_session_active = false;
 	ring_buf_reset(&usb_ring_buf);
@@ -375,8 +404,19 @@ static void on_dtr_change(bool dtr_active)
 
 	/* The session is over: main runs its per-session cleanup (contact dump,
 	 * sync, sign buffer) once no other transport is still connected. */
-	if (was_active && s_link && s_link->on_disconnected) {
-		s_link->on_disconnected();
+	usb_link_update();
+}
+
+/* Bus suspend, resume or reset, from the shared ZephyrUSBCDC module. */
+static void on_bus_change(void)
+{
+	bool was_up = usb_link_up;
+
+	usb_link_update();
+	if (usb_link_up && !was_up) {
+		/* Resumed. The class does not restart TX by itself: frames queued
+		 * before the suspend wait for this kick. */
+		uart_irq_tx_enable(usb_dev);
 	}
 }
 #endif /* COMPANION_HAS_DTR */
@@ -455,7 +495,7 @@ size_t zephcore_usb_companion_recv(uint8_t *dest)
 
 bool zephcore_usb_companion_is_connected(void)
 {
-	return usb_session_active && !usb_session_is_text;
+	return usb_link_up && !usb_session_is_text;
 }
 
 /* Only a connected session is ever busy: MultiSerialInterface asks every
@@ -516,6 +556,7 @@ void zephcore_usb_companion_init(const struct companion_link_cbs *link)
 		 * shared usbd_msg_callback — no polling work needed.  Plain-UART
 		 * backends have no DTR; their session reset is protocol-driven. */
 		zephcore_usbd_set_dtr_cb(on_dtr_change);
+		zephcore_usbd_set_bus_cb(on_bus_change);
 #endif
 	} else {
 		LOG_WRN("Companion UART not ready");

zephcore/adapters/usb/ZephyrCompanionUSB.h

@@ -21,8 +21,9 @@ extern "C" {
 
 /**
  * Initialize the transport: ring buffers, UART ISR, DTR tracking.
- * @param link  frame waiting / TX drained / session start / session end
- *              (DTR drop). Raised from the ISR and sysworkq: post events only.
+ * @param link  frame waiting / TX drained / session start (also a bus resume)
+ *              / session end (DTR drop, VBUS loss, bus reset; also a bus
+ *              suspend). Raised from the ISR and sysworkq: post events only.
  */
 void zephcore_usb_companion_init(const struct companion_link_cbs *link);
 
@@ -36,7 +37,8 @@ size_t zephcore_usb_companion_write_frame(const uint8_t *src, size_t len);
 /** Take the next received binary frame into dest (MAX_FRAME_SIZE). Returns its length, 0 if none. */
 size_t zephcore_usb_companion_recv(uint8_t *dest);
 
-/** A binary companion session is open (a text-CLI session is not a client). */
+/** A binary companion session is open and the bus is not suspended (a
+ *  text-CLI session is not a client). */
 bool zephcore_usb_companion_is_connected(void);
 
 /** The TX ring cannot take another full-size frame. */

zephcore/adapters/usb/ZephyrUSBCDC.cpp

@@ -8,8 +8,9 @@
  *     SET_LINE_CODING requests reach us as events (no DTR polling)
  *   - Emits a k_event when DTR transitions high — the boot path waits on it
  *     instead of a fixed sleep
- *   - Fires a user callback on every DTR transition (companion: reset RX +
- *     flip active_iface on drop)
+ *   - Fires a user callback on every DTR transition (companion: end the
+ *     session on drop), and reports VBUS loss and a bus reset as a drop
+ *   - Fires a user callback on bus suspend, resume and reset
  *   - Handles the Arduino-style 1200-baud touch → reboot-to-bootloader flow
  *     for nRF52 boards
  */
@@ -71,6 +72,7 @@ static K_EVENT_DEFINE(usb_cdc_events);
 static bool s_dtr_active;
 static bool s_initialized;
 static zephcore_usbd_cdc_dtr_cb_t s_dtr_cb;
+static zephcore_usbd_cdc_bus_cb_t s_bus_cb;
 
 /* ZephyrBoard for bootloader-magic write before reset. The class is stateless
  * (only static methods over GPREGRET + sys_reboot), so a local instance here
@@ -86,6 +88,17 @@ static void enter_bootloader(void)
 	CODE_UNREACHABLE;
 }
 
+/* The host went away without a DTR=0: report it as a DTR drop. */
+static void host_gone(void)
+{
+	if (s_dtr_active) {
+		s_dtr_active = false;
+		if (s_dtr_cb) {
+			s_dtr_cb(false);
+		}
+	}
+}
+
 /* ===== USBD message callback ===== */
 static void usbd_msg_callback(struct usbd_context *const ctx,
 			      const struct usbd_msg *msg)
@@ -142,11 +155,24 @@ static void usbd_msg_callback(struct usbd_context *const ctx,
 		 * connection until reboot).  Treat VBUS loss as a DTR drop so the
 		 * interface is handed back to BLE. */
 		LOG_INF("CDC ACM: VBUS removed (device unplug)");
-		if (s_dtr_active) {
-			s_dtr_active = false;
-			if (s_dtr_cb) {
-				s_dtr_cb(false);
-			}
+		host_gone();
+	} else if (msg->type == USBD_MSG_RESET) {
+		/* Bus reset.  At enumeration no port is open and this does nothing.
+		 * Later it means the host is enumerating us again (a hub upstream
+		 * was reset, or the host lost the device): the port it had open is
+		 * gone, and no DTR=0 says so, since the class keeps the line state
+		 * of the old session.  VBUS can stay up throughout, so treat it as
+		 * a DTR drop too.  A reset also ends a suspend, with no RESUME. */
+		LOG_INF("CDC ACM: bus reset");
+		host_gone();
+		if (s_bus_cb) {
+			s_bus_cb();
+		}
+	} else if (msg->type == USBD_MSG_SUSPEND || msg->type == USBD_MSG_RESUME) {
+		LOG_INF("CDC ACM: bus %s",
+			msg->type == USBD_MSG_SUSPEND ? "suspended" : "resumed");
+		if (s_bus_cb) {
+			s_bus_cb();
 		}
 	}
 }
@@ -268,6 +294,16 @@ extern "C" void zephcore_usbd_set_dtr_cb(zephcore_usbd_cdc_dtr_cb_t cb)
 	s_dtr_cb = cb;
 }
 
+extern "C" bool zephcore_usbd_is_suspended(void)
+{
+	return s_initialized && usbd_is_suspended(&zephcore_usbd);
+}
+
+extern "C" void zephcore_usbd_set_bus_cb(zephcore_usbd_cdc_bus_cb_t cb)
+{
+	s_bus_cb = cb;
+}
+
 extern "C" void zephcore_usbd_detach(void)
 {
 	if (!s_initialized) {

zephcore/adapters/usb/ZephyrUSBCDC.h

@@ -20,9 +20,14 @@ extern "C" {
 #endif
 
 /* Per-transition DTR callback. Fires on every host CONTROL_LINE_STATE change,
- * value = current DTR level. NULL is allowed (cb cleared). */
+ * value = current DTR level, and with false when the host goes away without
+ * one (VBUS loss, bus reset). NULL is allowed (cb cleared). */
 typedef void (*zephcore_usbd_cdc_dtr_cb_t)(bool dtr_active);
 
+/* Bus state callback: the bus was suspended, resumed or reset. Read the state
+ * with zephcore_usbd_is_suspended(). NULL is allowed (cb cleared). */
+typedef void (*zephcore_usbd_cdc_bus_cb_t)(void);
+
 /* Initialize USB device + CDC ACM class and enumerate.
  * Idempotent; subsequent calls are no-ops.
  * Returns 0 on success or a negative errno. */
@@ -37,9 +42,16 @@ int zephcore_usbd_wait_dtr(uint32_t timeout_ms);
 bool zephcore_usbd_is_dtr_active(void);
 
 /* Register a callback fired on every DTR transition.
- * Companion uses this to reset its RX state and flip active_iface on drop. */
+ * Companion uses this to end its session on a drop. */
 void zephcore_usbd_set_dtr_cb(zephcore_usbd_cdc_dtr_cb_t cb);
 
+/* The host has suspended the bus (asleep with the port open): nothing we send
+ * leaves the device until it resumes. The USB stack's own state. */
+bool zephcore_usbd_is_suspended(void);
+
+/* Register a callback fired on a bus suspend, resume or reset. */
+void zephcore_usbd_set_bus_cb(zephcore_usbd_cdc_bus_cb_t cb);
+
 /* Detach from the USB bus (drop the D+ pull-up) so the host sees an unplug.
  * Call before a reset: a soft reset leaves the PHY attached on some SoCs, and
  * the host then keeps a stale endpoint open across the reboot. No-op if the