target/cortex_m: supress historical reset detection

[fw/openocd] / src / target / cortex_m.c

diff --git a/src/target/cortex_m.c b/src/target/cortex_m.c
index 9497aa0373a0e8aee94b15a8ab3ba66e47065845..aeaeb182945dd6992be42552b153c08baf884f45 100644 (file)
--- a/src/target/cortex_m.c
+++ b/src/target/cortex_m.c
@@ -652,6 +652,11 @@ static int cortex_m_endreset_event(struct target *target)
 
        register_cache_invalidate(armv7m->arm.core_cache);
 
+       /* TODO: invalidate also working areas (needed in the case of detected reset).
+        * Doing so will require flash drivers to test if working area
+        * is still valid in all target algo calling loops.
+        */
+
        /* make sure we have latest dhcsr flags */
        retval = cortex_m_read_dhcsr_atomic_sticky(target);
        if (retval != ERROR_OK)
@@ -2396,6 +2401,20 @@ int cortex_m_examine(struct target *target)
                retval = target_read_u32(target, DCB_DHCSR, &cortex_m->dcb_dhcsr);
                if (retval != ERROR_OK)
                        return retval;
+
+               /*  Don't cumulate sticky S_RESET_ST at the very first read of DHCSR
+                *  as S_RESET_ST may indicate a reset that happened long time ago
+                *  (most probably the power-on reset before OpenOCD was started).
+                *  As we are just initializing the debug system we do not need
+                *  to call cortex_m_endreset_event() in the following poll.
+                */
+               if (!cortex_m->dcb_dhcsr_sticky_is_recent) {
+                       cortex_m->dcb_dhcsr_sticky_is_recent = true;
+                       if (cortex_m->dcb_dhcsr & S_RESET_ST) {
+                               LOG_TARGET_DEBUG(target, "reset happened some time ago, ignore");
+                               cortex_m->dcb_dhcsr &= ~S_RESET_ST;
+                       }
+               }
                cortex_m_cumulate_dhcsr_sticky(cortex_m, cortex_m->dcb_dhcsr);
 
                if (!(cortex_m->dcb_dhcsr & C_DEBUGEN)) {