qmk_firmware/tmk_core/tool/chibios/ch-bootloader-jump.patch

diff --git a/os/common/ports/ARMCMx/compilers/GCC/crt0_v6m.s b/os/common/ports/ARMCMx/compilers/GCC/crt0_v6m.s
index 51a79bb..42d07bd 100644
--- a/os/common/ports/ARMCMx/compilers/GCC/crt0_v6m.s
+++ b/os/common/ports/ARMCMx/compilers/GCC/crt0_v6m.s
@@ -105,6 +105,13 @@
 #define CRT0_CALL_DESTRUCTORS               TRUE
 #endif
 
+/**
+ * @brief   Magic number for jumping to bootloader.
+ */
+#if !defined(MAGIC_BOOTLOADER_NUMBER) || defined(__DOXYGEN__)
+#define MAGIC_BOOTLOADER_NUMBER 0xDEADBEEF
+#endif
+
 /*===========================================================================*/
 /* Code section.                                                             */
 /*===========================================================================*/
@@ -124,6 +131,17 @@
                 .thumb_func
                 .global Reset_Handler
 Reset_Handler:
+
+#ifdef STM32_BOOTLOADER_ADDRESS
+                /* jump to bootloader code */
+                ldr        r0, =__ram0_end__-4
+                ldr        r1, =MAGIC_BOOTLOADER_NUMBER
+                ldr        r2, [r0, #0]
+                str        r0, [r0, #0] /* erase stored magic */
+                cmp        r2, r1
+                beq        Bootloader_Jump
+#endif /* STM32_BOOTLOADER_ADDRESS */
+
                 /* Interrupts are globally masked initially.*/
                 cpsid   i
 
@@ -242,6 +260,21 @@ endfiniloop:
                 ldr     r1, =__default_exit
                 bx      r1
 
+#ifdef STM32_BOOTLOADER_ADDRESS
+/*
+ * Jump-to-bootloader function.
+ */
+
+                .align  2
+                .thumb_func
+Bootloader_Jump:
+                ldr     r0, =STM32_BOOTLOADER_ADDRESS
+                ldr     r1, [r0, #0]
+                mov     sp, r1
+                ldr     r0, [r0, #4]
+                bx      r0
+#endif /* STM32_BOOTLOADER_ADDRESS */
+
 #endif
 
 /** @} */
diff --git a/os/common/ports/ARMCMx/compilers/GCC/crt0_v7m.s b/os/common/ports/ARMCMx/compilers/GCC/crt0_v7m.s
index 4812a29..dca9f88 100644
--- a/os/common/ports/ARMCMx/compilers/GCC/crt0_v7m.s
+++ b/os/common/ports/ARMCMx/compilers/GCC/crt0_v7m.s
@@ -140,6 +140,13 @@
 #define CRT0_CPACR_INIT                     0x00F00000
 #endif
 
+/**
+ * @brief   Magic number for jumping to bootloader.
+ */
+#if !defined(MAGIC_BOOTLOADER_NUMBER) || defined(__DOXYGEN__)
+#define MAGIC_BOOTLOADER_NUMBER 0xDEADBEEF
+#endif
+
 /*===========================================================================*/
 /* Code section.                                                             */
 /*===========================================================================*/
@@ -164,6 +171,17 @@
                 .thumb_func
                 .global Reset_Handler
 Reset_Handler:
+
+#ifdef STM32_BOOTLOADER_ADDRESS
+                /* jump to bootloader code */
+                ldr        r0, =__ram0_end__-4
+                ldr        r1, =MAGIC_BOOTLOADER_NUMBER
+                ldr        r2, [r0, #0]
+                str        r0, [r0, #0] /* erase stored magic */
+                cmp        r2, r1
+                beq        Bootloader_Jump
+#endif /* STM32_BOOTLOADER_ADDRESS */
+
                 /* Interrupts are globally masked initially.*/
                 cpsid   i
 
@@ -305,6 +323,21 @@ endfiniloop:
                 /* Branching to the defined exit handler.*/
                 b       __default_exit
 
+#ifdef STM32_BOOTLOADER_ADDRESS
+/*
+ * Jump-to-bootloader function.
+ */
+
+                .align  2
+                .thumb_func
+Bootloader_Jump:
+                ldr     r0, =STM32_BOOTLOADER_ADDRESS
+                ldr     r1, [r0, #0]
+                mov     sp, r1
+                ldr     r0, [r0, #4]
+                bx      r0
+#endif /* STM32_BOOTLOADER_ADDRESS */
+
 #endif /* !defined(__DOXYGEN__) */
 
 /** @} */