adi_v5_swd: add jtag-to-swd through dormant

ARM IHI 0031A does not support SWJ-DP, so no switch between JTAG
and SWD is considered.
ARM IHI 0031B is not publicly available and it's reported as
"Confidential Beta" in the history list in following doc versions.
From ARM IHI 0031C the direct switch between JTAG and SWD is
already deprecated in favor of passing through dormant mode. With
no access to IHI 0031B we haven't info if any device strictly
requires the direct switch.

OpenOCD implements only the deprecated direct switch, so changing
it could cause regression on devices that do not implement dormant
mode.
Plus, not all the adapters support dormant mode.

Nevertheless there are already target devices that only allow
entering in SWD by passing through dormant.

Let the code try both method, alternating one tentative with the
deprecated legacy direct switch, then another tentative passing
through dormant, and repeat till timeout.
This would work on any device that don't support dormant, on new
devices that require switch through dormant and will work with
adapters that don't support dormant.

Change-Id: Ib8619635277d497872079a33fa4e38be9beb84a0
Signed-off-by: Antonio Borneo <borneo.antonio@gmail.com>
Reviewed-on: https://review.openocd.org/c/openocd/+/6695
Tested-by: jenkins

diff --git a/src/target/adi_v5_swd.c b/src/target/adi_v5_swd.c
index c23cee157d53751e0a24f59879f078b76ac83617..68350424372bf6905fa38f456b47e7d23bb308c2 100644 (file)
--- a/src/target/adi_v5_swd.c
+++ b/src/target/adi_v5_swd.c
@@ -315,7 +315,12 @@ static int swd_connect_single(struct adiv5_dap *dap)
        int64_t timeout = timeval_ms() + 500;
 
        do {
-               swd_send_sequence(dap, JTAG_TO_SWD);
+               if (dap->switch_through_dormant) {
+                       swd_send_sequence(dap, JTAG_TO_DORMANT);
+                       swd_send_sequence(dap, DORMANT_TO_SWD);
+               } else {
+                       swd_send_sequence(dap, JTAG_TO_SWD);
+               }
 
                /* Clear link state, including the SELECT cache. */
                dap->do_reconnect = false;
@@ -330,6 +335,7 @@ static int swd_connect_single(struct adiv5_dap *dap)
 
                alive_sleep(1);
 
+               dap->switch_through_dormant = !dap->switch_through_dormant;
        } while (timeval_ms() < timeout);
 
        if (retval != ERROR_OK) {
@@ -568,7 +574,12 @@ static void swd_quit(struct adiv5_dap *dap)
                 * swd->switch_seq(DORMANT_TO_JTAG);
                 */
        } else {
-               swd->switch_seq(SWD_TO_JTAG);
+               if (dap->switch_through_dormant) {
+                       swd->switch_seq(SWD_TO_DORMANT);
+                       swd->switch_seq(DORMANT_TO_JTAG);
+               } else {
+                       swd->switch_seq(SWD_TO_JTAG);
+               }
        }
 
        /* flush the queue to shift out the sequence before exit */

diff --git a/src/target/arm_adi_v5.h b/src/target/arm_adi_v5.h
index 758cfa096d1984e896adac25011286eaca3b6442..5c598f16e34a47ae41a1be6a22a74eb86968ab13 100644 (file)
--- a/src/target/arm_adi_v5.h
+++ b/src/target/arm_adi_v5.h
@@ -342,6 +342,11 @@ struct adiv5_dap {
        bool multidrop_dp_id_valid;
        /** TINSTANCE field of multidrop_targetsel has been configured */
        bool multidrop_instance_id_valid;
+
+       /**
+        * Record if enter in SWD required passing through DORMANT
+        */
+       bool switch_through_dormant;
 };
 
 /**