prevent abort via polling during jtag_reset

Observed:

  openocd: core.c:318: jtag_checks: Assertion `jtag_trst == 0' failed.

The issue was that nothing disabled background polling during calls
from the TCL shell to "jtag_reset 1 1".  Fix by moving the existing
poll-disable mechanism to the JTAG layer where it belongs, and then
augmenting it to always pay attention to TRST and SRST.

Signed-off-by: David Brownell <dbrownell@users.sourceforge.net>

diff --git a/src/jtag/core.c b/src/jtag/core.c
index b8235eb1e969358f4992368a4e7fd2cbc5df9e98..bdfd6e5b259b90af1505c7a62442ea6bedd92b17 100644 (file)
--- a/src/jtag/core.c
+++ b/src/jtag/core.c
@@ -137,6 +137,32 @@ int jtag_error_clear(void)
        return temp;
 }
 
+/************/
+
+static bool jtag_poll = 1;
+
+bool is_jtag_poll_safe(void)
+{
+       /* Polling can be disabled explicitly with set_enabled(false).
+        * It is also implicitly disabled while TRST is active and
+        * while SRST is gating the JTAG clock.
+        */
+       if (!jtag_poll || jtag_trst != 0)
+               return false;
+       return jtag_srst == 0 || (jtag_reset_config & RESET_SRST_NO_GATING);
+}
+
+bool jtag_poll_get_enabled(void)
+{
+       return jtag_poll;
+}
+
+void jtag_poll_set_enabled(bool value)
+{
+       jtag_poll = value;
+}
+
+/************/
 
 jtag_tap_t *jtag_all_taps(void)
 {

diff --git a/src/jtag/jtag.h b/src/jtag/jtag.h
index 0126b3310294d1d0c1280af1f8e122828e5da94a..5085445f3474755bb2688b7cfeac21b4de3d45ae 100644 (file)
--- a/src/jtag/jtag.h
+++ b/src/jtag/jtag.h
@@ -737,4 +737,21 @@ int jtag_get_error(void);
  */
 int jtag_error_clear(void);
 
+/**
+ * Return true if it's safe for a background polling task to access the
+ * JTAG scan chain.  Polling may be explicitly disallowed, and is also
+ * unsafe while nTRST is active or the JTAG clock is gated off.,
+ */
+bool is_jtag_poll_safe(void);
+
+/**
+ * Return flag reporting whether JTAG polling is disallowed.
+ */
+bool jtag_poll_get_enabled(void);
+
+/**
+ * Assign flag reporting whether JTAG polling is disallowed.
+ */
+void jtag_poll_set_enabled(bool value);
+
 #endif /* JTAG_H */

diff --git a/src/target/target.c b/src/target/target.c
index 253a7e464efa8970a2263384a8c8268e20e2aaa2..ced09e900966f36d2042868cdafcc47fd4e30b00 100644 (file)
--- a/src/target/target.c
+++ b/src/target/target.c
@@ -269,8 +269,6 @@ static int new_target_number(void)
        return x + 1;
 }
 
-static int target_continuous_poll = 1;
-
 /* read a uint32_t from a buffer in target memory endianness */
 uint32_t target_buffer_get_u32(target_t *target, const uint8_t *buffer)
 {
@@ -436,13 +434,14 @@ int target_process_reset(struct command_context_s *cmd_ctx, enum target_reset_mo
         * more predictable, i.e. dr/irscan & pathmove in events will
         * not have JTAG operations injected into the middle of a sequence.
         */
-       int save_poll = target_continuous_poll;
-       target_continuous_poll = 0;
+       bool save_poll = jtag_poll_get_enabled();
+
+       jtag_poll_set_enabled(false);
 
        sprintf(buf, "ocd_process_reset %s", n->name);
        retval = Jim_Eval(interp, buf);
 
-       target_continuous_poll = save_poll;
+       jtag_poll_set_enabled(save_poll);
 
        if (retval != JIM_OK) {
                Jim_PrintErrorMessage(interp);
@@ -1726,7 +1725,7 @@ int handle_target(void *priv)
         * Skip targets that are currently disabled.
         */
        for (target_t *target = all_targets;
-                       target_continuous_poll && target;
+                       is_jtag_poll_safe() && target;
                        target = target->next)
        {
                if (!target->tap->enabled)
@@ -1886,7 +1885,7 @@ static int handle_poll_command(struct command_context_s *cmd_ctx, char *cmd, cha
        if (argc == 0)
        {
                command_print(cmd_ctx, "background polling: %s",
-                               target_continuous_poll ?  "on" : "off");
+                               jtag_poll_get_enabled() ? "on" : "off");
                command_print(cmd_ctx, "TAP: %s (%s)",
                                target->tap->dotted_name,
                                target->tap->enabled ? "enabled" : "disabled");
@@ -1902,11 +1901,11 @@ static int handle_poll_command(struct command_context_s *cmd_ctx, char *cmd, cha
        {
                if (strcmp(args[0], "on") == 0)
                {
-                       target_continuous_poll = 1;
+                       jtag_poll_set_enabled(true);
                }
                else if (strcmp(args[0], "off") == 0)
                {
-                       target_continuous_poll = 0;
+                       jtag_poll_set_enabled(false);
                }
                else
                {