[ion] USB::Device::Calculator::PollAndReset

Change-Id: Ib847b5f8a0fd559f98c1c130c0b0daffaf4c6468

ion/src/device/boot/dfu.ld

@@ -28,7 +28,7 @@ MEMORY {
 SECTIONS {
   .text : {
     . = ALIGN(4);
-    KEEP(*(.text._ZN3Ion3USB6Device10Calculator4PollEv))
+    KEEP(*(.text._ZN3Ion3USB6Device10Calculator12PollAndResetEv))
     *(.text)
     *(.text.*)
   } >RAM_BUFFER

ion/src/device/usb/calculator.cpp

@@ -7,7 +7,7 @@ namespace Ion {
 namespace USB {
 namespace Device {
 
-void Calculator::Poll() {
+bool Calculator::PollAndReset() {
   Calculator c;
 
   /* Leave DFU mode if the Back key is pressed, the calculator unplugged or the
@@ -24,6 +24,8 @@ void Calculator::Poll() {
   if (!c.isSoftDisconnected()) {
     c.detach();
   }
+
+  return false;
 }
 
 Descriptor * Calculator::descriptor(uint8_t type, uint8_t index) {

ion/src/device/usb/calculator.h

@@ -24,7 +24,7 @@ namespace Device {
 
 class Calculator : public Device {
 public:
-  static void Poll();
+  static bool PollAndReset(); // Return true if reset is needed
   Calculator() :
     Device(&m_dfuInterface),
     m_deviceDescriptor(

ion/src/device/usb_dfu_relocated_ram.cpp

@@ -10,7 +10,7 @@ extern char _dfu_bootloader_flash_end;
 namespace Ion {
 namespace USB {
 
-typedef void (*FunctionPointer)();
+typedef bool (*PollFunctionPointer)(void);
 
 void DFU() {
 
@@ -51,7 +51,7 @@ void DFU() {
   /* 4- Jump to DFU bootloader code. We made sure in the linker script that the
    * first function we want to call is at the beginning of the DFU code. */
 
-  FunctionPointer dfu_bootloader_entry = reinterpret_cast<FunctionPointer>(dfu_bootloader_ram_start);
+  PollFunctionPointer dfu_bootloader_entry = reinterpret_cast<PollFunctionPointer>(dfu_bootloader_ram_start);
 
   /* To have the right debug symbols for the reallocated code, break here and:
    *  - Get the address of the new .text section
@@ -62,7 +62,14 @@ void DFU() {
    *        add-symbol-file ion/src/device/usb/dfu.elf 0x20038000
    */
 
-  dfu_bootloader_entry();
+  if (dfu_bootloader_entry()) {
+    /* We don't perform a core reset because at this point in time the USB cable
+     * is most likely plugged in. Doing a full core reset would be the clean
+     * thing to do but would therefore result in the device entering the ROMed
+     * DFU bootloader, which we want to avoid. By performing a jump-reset, we
+     * will enter the newly flashed firmware. */
+    Ion::Device::jumpReset();
+  }
 
   /* 5- That's all. The DFU bootloader on the stack is now dead code that will
    * be overwritten when the stack grows. */

ion/src/device/usb_dfu_xip_flash.cpp

@@ -1,10 +1,13 @@
 #include "usb/calculator.h"
+#include <ion.h>
 
 namespace Ion {
 namespace USB {
 
 void DFU() {
-  Ion::USB::Device::Calculator::Poll();
+  if (Ion::USB::Device::Calculator::PollAndReset()) {
+    Ion::Device::jumpReset();
+  }
 }
 
 }