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-rw-r--r--flashstub/stm32.s42
1 files changed, 42 insertions, 0 deletions
diff --git a/flashstub/stm32.s b/flashstub/stm32.s
new file mode 100644
index 0000000..b27d8b2
--- /dev/null
+++ b/flashstub/stm32.s
@@ -0,0 +1,42 @@
+.global _start
+
+_start:
+ ldr r0, _flashbase
+ ldr r1, _addr
+ mov r2, pc
+ add r2, #(_data - . - 2)
+ ldr r3, _size
+ mov r5, #1
+_next:
+ cbz r3, _done
+ @ Write PG command to FLASH_CR
+ str r5, [r0, #0x10]
+ @ Write data to flash (half-word)
+ ldrh r4, [r2]
+ strh r4, [r1]
+
+_wait: @ Wait for BSY bit to clear
+ ldr r4, [r0, #0x0C]
+ mov r6, #1
+ tst r4, r6
+ bne _wait
+
+ sub r3, #2
+ add r1, #2
+ add r2, #2
+ b _next
+_done:
+ bkpt
+
+@.align 4
+.org 0x28
+_flashbase:
+ .word 0x40022000
+_addr:
+ .word 0
+_size:
+ .word 12
+_data:
+ .word 0xAAAAAAAA
+ .word 0xBBBBBBBB
+ .word 0xCCCCCCCC