[ion] DFU reallocation: clean DCache after copying the DFU bootloader to the RAM

ion/src/device/shared/usb/Makefile

@@ -47,6 +47,7 @@ dfu_src += liba/src/memset.c
 dfu_src += liba/src/memcpy.c
 dfu_src += libaxx/src/cxxabi/pure_virtual.cpp
 dfu_src += ion/src/device/shared/usb/boot.cpp
+dfu_src += ion/src/device/$(MODEL)/drivers/cache.cpp
 dfu_src += $(addprefix ion/src/device/shared/drivers/, \
   base64.cpp \
   external_flash.cpp \

ion/src/device/shared/usb/dfu_relocated.cpp

@@ -1,6 +1,7 @@
 #include <ion/usb.h>
 #include <string.h>
 #include <assert.h>
+#include <drivers/cache.h>
 #include "../drivers/timing.h"
 
 extern char _stack_end;
@@ -47,6 +48,12 @@ void DFU() {
   /* 3- Copy the DFU bootloader from Flash to RAM. */
 
   memcpy(dfu_bootloader_ram_start, &_dfu_bootloader_flash_start, dfu_bootloader_size);
+  /* The DFU bootloader might have been copied in the DCache. However, when we
+   * run the instructions from the DFU bootloader, the CPU looks for
+   * instructions in the ICache and then in the RAM. We thus need to flush the
+   * DCache to update the RAM. */
+  // Flush data cache
+  Device::Cache::cleanDCache();
 
   /* 4- Disable all interrupts
    * The interrupt service routines live in the Flash and could be overwritten