pbio/drv/usb_stm32: Simplify event loop and use pbio/os.

BCD and data handling happen separately, so we can have them chronologically in the process thread.

Also fix a revisit note for not needing a timer to resend the status. Since we recently introduced status scheduling by the host module, we can just re-schedule the latest on subscribing.

Also introduce shutting down via pbdrv_deinit rather than polling statuses from pbsys.

Author: laurensvalk

lib/pbio/drv/core.c

@@ -90,6 +90,7 @@ void pbdrv_deinit(void) {
     pbdrv_imu_deinit();
     pbdrv_bluetooth_deinit();
     pbdrv_button_deinit();
+    pbdrv_usb_deinit();
 
     while (pbio_busy_count_busy()) {
         pbio_os_run_processes_and_wait_for_event();

lib/pbio/drv/usb/usb.h

@@ -11,13 +11,19 @@
 #if PBDRV_CONFIG_USB
 
 /**
- * Initializes the USB driver.
+ * Initializes the USB driver on boot.
  */
 void pbdrv_usb_init(void);
 
+/**
+ * De-initializes the USB driver for data transfers on soft-poweroff. Keeps charging if supported.
+ */
+void pbdrv_usb_deinit(void);
+
 #else // PBDRV_CONFIG_USB
 
 #define pbdrv_usb_init()
+#define pbdrv_usb_deinit()
 
 #endif // PBDRV_CONFIG_USB