[OpenOCD-commit] Main OpenOCD repository branch, master, updated. v0.11.0-803-g3adbec9aa

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- Log -----------------------------------------------------------------
commit 3adbec9aab95808222071eb09014f28fbb6ad1be
Author: Tomas Vanek <va...@fb...>
Date:   Tue Aug 2 11:44:43 2022 +0200

    target/cortex_m: supress historical reset detection
    
    The S_RESET_ST sticky bit is reset after DHCSR read.
    It is set at power-on reset and keeps active until the debuger reads DHCSR.
    
    Ignore S_RESET_ST at the very first read after OpenOCD start
    and suppress possibly misleading message "external reset detected"
    if we cannot guarantee the reset happened recently.
    
    While on it add a TODO comment.
    
    Change-Id: I15217c2ca6f69ac97aff8be86bce67cba94a42cd
    Signed-off-by: Tomas Vanek <va...@fb...>
    Reviewed-on: https://review.openocd.org/c/openocd/+/7109
    Tested-by: jenkins
    Reviewed-by: Antonio Borneo <bor...@gm...>

diff --git a/src/target/cortex_m.c b/src/target/cortex_m.c
index 9497aa037..aeaeb1829 100644
--- 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)) {
diff --git a/src/target/cortex_m.h b/src/target/cortex_m.h
index 168613590..69368a919 100644
--- a/src/target/cortex_m.h
+++ b/src/target/cortex_m.h
@@ -206,6 +206,8 @@ struct cortex_m_common {
 	/* Context information */
 	uint32_t dcb_dhcsr;
 	uint32_t dcb_dhcsr_cumulated_sticky;
+	/* DCB DHCSR has been at least once read, so the sticky bits have been reset */
+	bool dcb_dhcsr_sticky_is_recent;
 	uint32_t nvic_dfsr;  /* Debug Fault Status Register - shows reason for debug halt */
 	uint32_t nvic_icsr;  /* Interrupt Control State Register - shows active and pending IRQ */
 

-----------------------------------------------------------------------

Summary of changes:
 src/target/cortex_m.c | 19 +++++++++++++++++++
 src/target/cortex_m.h |  2 ++
 2 files changed, 21 insertions(+)


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