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-rw-r--r--scripts/stubs/stm32_optprog.S52
1 files changed, 52 insertions, 0 deletions
diff --git a/scripts/stubs/stm32_optprog.S b/scripts/stubs/stm32_optprog.S
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+++ b/scripts/stubs/stm32_optprog.S
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+@; Assembler sequence to program option bytes on STM32
+@; Takes option address in r0 and value in r1.
+@; Ends with BKPT instruction
+.global _start
+
+.equ FLASHBASE, 0x40022000
+
+.equ KEY1, 0x45670123
+.equ KEY2, 0xCDEF89AB
+
+.equ FLASH_KEY, 0x04
+.equ FLASH_OPTKEY, 0x08
+.equ FLASH_CR, 0x10
+.equ FLASH_SR, 0x0C
+
+.equ OPTPG, 0x10
+
+.equ BSY, 0x01
+
+.syntax unified
+
+_start:
+ @; Load FLASH controller base address
+ ldr r2, =FLASHBASE
+
+ @; Do unlocking sequence
+ ldr r3, =KEY1
+ str r3, [r2, #FLASH_KEY]
+ ldr r3, =KEY2
+ str r3, [r2, #FLASH_KEY]
+
+ @; Same for option bytes
+ ldr r3, =KEY1
+ str r3, [r2, #FLASH_OPTKEY]
+ ldr r3, =KEY2
+ str r3, [r2, #FLASH_OPTKEY]
+
+ @; Set OPTPG bit in FLASH_CR
+ ldr r3, [r2, #FLASH_CR]
+ orr r3, r3, #OPTPG
+ str r3, [r2, #FLASH_CR]
+ @; Write data at address
+ strh r1, [r0]
+
+_wait: @; Wait for BSY bit to clear
+ ldr r4, [r2, #FLASH_SR]
+ mov r6, #BSY
+ tst r4, r6
+ bne _wait
+
+ bkpt
+