CTRL keyboard bootloader_jump support

Adds support for CTRL keyboards to enter bootloader via bootloader_jump()

tmk_core/protocol/arm_atsam/md_bootloader.h

@@ -7,6 +7,13 @@ extern uint32_t _erom;
 
 #define BOOTLOADER_SERIAL_MAX_SIZE 20   //DO NOT MODIFY!
 
+#ifdef KEYBOARD_massdrop_ctrl
+//WARNING: These are only for CTRL bootloader release "v2.18Jun 22 2018 17:28:08" for bootloader_jump support
+extern uint32_t _eram;
+#define BOOTLOADER_MAGIC 0x3B9ACA00
+#define MAGIC_ADDR (uint32_t *)(&_eram - 4)
+#endif
+
 #ifdef MD_BOOTLOADER
 
 #define MCU_HZ 48000000

tmk_core/protocol/arm_atsam/startup.c

@@ -28,6 +28,7 @@
  */
 
 #include "samd51.h"
+#include "md_bootloader.h"
 
 /* Initialize segments */
 extern uint32_t _sfixed;
@@ -500,6 +501,16 @@ const DeviceVectors exception_table = {
  */
 void Reset_Handler(void)
 {
+#ifdef KEYBOARD_massdrop_ctrl
+        /* WARNING: This is only for CTRL bootloader release "v2.18Jun 22 2018 17:28:08" for bootloader_jump support */
+        if (*MAGIC_ADDR == BOOTLOADER_MAGIC) {
+                /* At this point, the bootloader's memory is initialized properly, so undo the jump to here, then jump back */
+                *MAGIC_ADDR = 0x00000000;           /* Change value to prevent potential bootloader entrance loop */
+                __set_MSP(0x20008818);              /* MSP according to bootloader */
+                SCB->VTOR = 0x00000000;             /* Vector table back to bootloader's */
+                asm("bx %0"::"r"(0x00001267));      /* Jump past bootloader RCAUSE check using THUMB */
+        }
+#endif
         uint32_t *pSrc, *pDest;
 
         /* Initialize the relocate segment */