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armcm_boot: No need to reset cpu state on bootup

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The bootloader is only called after a reset - it doesn't need to worry
about another bootloader launching it.  This reduces the code size by
a small amount.

Signed-off-by: Kevin O'Connor <kevin@koconnor.net>
This commit is contained in:
Kevin O'Connor 2022-05-04 20:28:06 -04:00 committed by Eric Callahan
parent 23f3c0e1e2
commit 726e6e62fa
1 changed files with 0 additions and 39 deletions
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39
src/generic/armcm_boot.c
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@ -35,39 +35,6 @@ set_bootup_code(uint64_t code)
void __noreturn __visible void __noreturn __visible
reset_handler_stage_two(void) reset_handler_stage_two(void)
{ {
int i;
// Clear all enabled user interrupts and user pending interrupts
for (i = 0; i < ARRAY_SIZE(NVIC->ICER); i++) {
NVIC->ICER[i] = 0xFFFFFFFF;
__DSB();
NVIC->ICPR[i] = 0xFFFFFFFF;
}
// Reset all user interrupt priorities
for (i = 0; i < ARRAY_SIZE(NVIC->IP); i++)
NVIC->IP[i] = 0;
// Disable SysTick interrupt
SysTick->CTRL = SysTick_CTRL_CLKSOURCE_Msk;
__DSB();
// Clear pending pendsv and systick interrupts
SCB->ICSR = SCB_ICSR_PENDSVCLR_Msk | SCB_ICSR_PENDSTCLR_Msk;
// Reset all system interrupt priorities
#if __CORTEX_M >= 7
for (i = 0; i < ARRAY_SIZE(SCB->SHPR); i++)
SCB->SHPR[i] = 0;
#else
for (i = 0; i < ARRAY_SIZE(SCB->SHP); i++)
SCB->SHP[i] = 0;
#endif
__DSB();
__ISB();
__enable_irq();
// Copy global variables from flash to ram // Copy global variables from flash to ram
uint32_t count = (&_data_end - &_data_start) * 4; uint32_t count = (&_data_end - &_data_start) * 4;
__builtin_memcpy(&_data_start, &_data_flash, count); __builtin_memcpy(&_data_start, &_data_flash, count);
@ -91,19 +58,13 @@ reset_handler_stage_two(void)
#define CANBOOT_SIGNATURE 0x21746f6f426e6143 // CanBoot! #define CANBOOT_SIGNATURE 0x21746f6f426e6143 // CanBoot!
// Initial code entry point - invoked by the processor after a reset // Initial code entry point - invoked by the processor after a reset
// Reset interrupts and stack to take control from bootloaders. Implemented
// Kevin's recommendation.
asm(".section .text.ResetHandler\n" asm(".section .text.ResetHandler\n"
".balign 8\n" ".balign 8\n"
".8byte " __stringify(CANBOOT_SIGNATURE) "\n" ".8byte " __stringify(CANBOOT_SIGNATURE) "\n"
".global ResetHandler\n" ".global ResetHandler\n"
".type ResetHandler, %function\n" ".type ResetHandler, %function\n"
"ResetHandler:\n" "ResetHandler:\n"
" cpsid i\n"
" ldr r3, =_stack_end\n"
" mov sp, r3\n"
" b reset_handler_stage_two\n" " b reset_handler_stage_two\n"
" .pool\n"
); );
extern void ResetHandler(); extern void ResetHandler();
DECL_ARMCM_IRQ(ResetHandler, -15); DECL_ARMCM_IRQ(ResetHandler, -15);