shared/runtime/tinyusb_helpers: Add TinyUSB helper functions.

Currently this file only includes a CDC jump-to-bootloader helper function.

shared/runtime/tinyusb_helpers.c

@@ -0,0 +1,54 @@
+/*
+ * This file is part of the MicroPython project, http://micropython.org/
+ *
+ * The MIT License (MIT)
+ *
+ * Copyright (c) 2022 Ibrahim Abdelkader <iabdalkader@openmv.io>
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+ * THE SOFTWARE.
+ */
+
+#include "py/runtime.h"
+#include "py/mphal.h"
+#include "modmachine.h"
+
+#if MICROPY_HW_USB_CDC_1200BPS_TOUCH
+
+#include "tusb.h"
+
+static mp_sched_node_t mp_bootloader_sched_node;
+
+STATIC void usbd_cdc_run_bootloader_task(mp_sched_node_t *node) {
+    mp_hal_delay_ms(250);
+    machine_bootloader(0, NULL);
+}
+
+void tud_cdc_line_state_cb(uint8_t itf, bool dtr, bool rts) {
+    if (dtr == false && rts == false) {
+        // Device is disconnected.
+        cdc_line_coding_t line_coding;
+        tud_cdc_n_get_line_coding(itf, &line_coding);
+        if (line_coding.bit_rate == 1200) {
+            // Delay bootloader jump to allow the USB stack to service endpoints.
+            mp_sched_schedule_node(&mp_bootloader_sched_node, usbd_cdc_run_bootloader_task);
+        }
+    }
+}
+
+#endif