x1000: fix hang that may occur in USB mode

Upon getting a USB reset, the USB core will update charging
current by calling usb_charging_maxcurrent_change(). On all
current X1000 targets this may cause a hang, since changing
the charge current involves a blocking I2C transaction.

Eg. if the host issues a reset when we're already configured
as part of error recovery, the change from 500 mA -> 100 mA
will cause a hang.

Change-Id: I5b45272c01fa16b179ae3d16bbc50c7fab9a416b

firmware/export/config/erosqnative.h

@@ -114,6 +114,7 @@
 #define USB_DEVBSS_ATTR __attribute__((aligned(32)))
 #define HAVE_USB_POWER
 #define HAVE_USB_CHARGING_ENABLE
+#define HAVE_USB_CHARGING_IN_THREAD
 #define TARGET_USB_CHARGING_DEFAULT USB_CHARGING_FORCE
 #define HAVE_BOOTLOADER_USB_MODE
 #endif

firmware/export/config/fiiom3k.h

@@ -114,6 +114,7 @@
 #define USB_DEVBSS_ATTR __attribute__((aligned(32)))
 #define HAVE_USB_POWER
 #define HAVE_USB_CHARGING_ENABLE
+#define HAVE_USB_CHARGING_IN_THREAD
 #define TARGET_USB_CHARGING_DEFAULT USB_CHARGING_FORCE
 #define HAVE_BOOTLOADER_USB_MODE
 #endif

firmware/export/config/shanlingq1.h

@@ -104,6 +104,7 @@
 #define USB_DEVBSS_ATTR __attribute__((aligned(32)))
 #define HAVE_USB_POWER
 #define HAVE_USB_CHARGING_ENABLE
+#define HAVE_USB_CHARGING_IN_THREAD
 #define HAVE_BOOTLOADER_USB_MODE
 #endif
 

firmware/usbstack/usb_core.c

@@ -928,8 +928,14 @@ void usb_core_bus_reset(void)
     usb_address = 0;
     usb_state = DEFAULT;
 #ifdef HAVE_USB_CHARGING_ENABLE
+#ifdef HAVE_USB_CHARGING_IN_THREAD
+    /* On some targets usb_charging_maxcurrent_change() cannot be called
+     * from an interrupt handler; get the USB thread to do it instead. */
+    usb_charger_update();
+#else
     usb_charging_maxcurrent_change(usb_charging_maxcurrent());
 #endif
+#endif
 }
 
 /* called by usb_drv_transfer_completed() */