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samples: boards: stm32: backup_sram: add magic value

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Stores a magic value togetter with the counter value, and resets the
counter in case that magic does not match.
A small magic value is not ideal, but should be good enough for the
sample and avoids pulling in a additional dependency e.g. on crc.

Signed-off-by: Thomas Stranger <thomas.stranger@outlook.com>
This commit is contained in:
Thomas Stranger 2024-08-22 21:39:48 +02:00 • committed by Alberto Escolar
commit d09e1d6e8f
1 changed files with 18 additions and 5 deletions
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23
samples/boards/stm32/backup_sram/src/main.c
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@ -12,8 +12,15 @@
#define BACKUP_DEV_COMPAT st_stm32_backup_sram #define BACKUP_DEV_COMPAT st_stm32_backup_sram
#endif #endif
#define BACKUP_MAGIC 0x600DCE11
struct backup_store {
uint32_t value;
uint32_t magic;
};
/** Value stored in backup SRAM. */ /** Value stored in backup SRAM. */
__stm32_backup_sram_section uint32_t backup_value; __stm32_backup_sram_section struct backup_store backup;
int main(void) int main(void)
{ {
@ -24,14 +31,20 @@ int main(void)
return 0; return 0;
} }
printk("Current value in backup SRAM (%p): %d\n", &backup_value, backup_value); if (backup.magic != BACKUP_MAGIC) {
backup.magic = BACKUP_MAGIC;
backup.value = 0;
printk("Invalid magic in backup SRAM structure - resetting value.\n");
}
backup_value++; printk("Current value in backup SRAM (%p): %d\n", &backup.value, backup.value);
backup.value++;
#if __DCACHE_PRESENT #if __DCACHE_PRESENT
SCB_CleanDCache_by_Addr(&backup_value, sizeof(backup_value)); SCB_CleanDCache_by_Addr(&backup, sizeof(backup));
#endif #endif
printk("Next reported value should be: %d\n", backup_value); printk("Next reported value should be: %d\n", backup.value);
printk("Keep VBAT power source and reset the board now!\n"); printk("Keep VBAT power source and reset the board now!\n");
return 0; return 0;
} }