prevent abort via polling during jtag_reset

[openocd.git] / src / jtag / core.c

diff --git a/src/jtag/core.c b/src/jtag/core.c
index f7d55b79301624e889e909d41537593c6b5e66d2..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)
 {
@@ -892,7 +918,15 @@ static bool jtag_examine_chain_check(uint8_t *idcodes, unsigned count)
        }
 
        /* if there wasn't a single non-zero bit or if all bits were one,
-        * the scan is not valid */
+        * the scan is not valid.  We wrote a mix of both values; either
+        *
+        *  - There's a hardware issue (almost certainly):
+        *     + all-zeroes can mean a target stuck in JTAG reset
+        *     + all-ones tends to mean no target
+        *  - The scan chain is WAY longer than we can handle, *AND* either
+        *     + there are several hundreds of TAPs in bypass, or
+        *     + at least a few dozen TAPs all have an all-ones IDCODE
+        */
        if (zero_check == 0x00 || one_check == 0xff)
        {
                LOG_ERROR("JTAG scan chain interrogation failed: all %s",
@@ -988,11 +1022,14 @@ static int jtag_examine_chain(void)
 {
        uint8_t idcode_buffer[JTAG_MAX_CHAIN_SIZE * 4];
        unsigned bit_count;
+       int retval;
 
        /* DR scan to collect BYPASS or IDCODE register contents.
         * Then make sure the scan data has both ones and zeroes.
         */
-       jtag_examine_chain_execute(idcode_buffer, JTAG_MAX_CHAIN_SIZE);
+       retval = jtag_examine_chain_execute(idcode_buffer, JTAG_MAX_CHAIN_SIZE);
+       if (retval != ERROR_OK)
+               return retval;
        if (!jtag_examine_chain_check(idcode_buffer, JTAG_MAX_CHAIN_SIZE))
                return ERROR_JTAG_INIT_FAILED;
 
@@ -1012,7 +1049,7 @@ static int jtag_examine_chain(void)
 
                if ((idcode & 1) == 0)
                {
-                       /* LSB must not be 0, this indicates a device in bypass */
+                       /* Zero for LSB indicates a device in bypass */
                        LOG_WARNING("TAP %s does not have IDCODE",
                                        tap->dotted_name);
                        idcode = 0;
@@ -1024,7 +1061,8 @@ static int jtag_examine_chain(void)
                {
                        /* Friendly devices support IDCODE */
                        tap->hasidcode = true;
-                       jtag_examine_chain_display(LOG_LVL_INFO, "tap/device found",
+                       jtag_examine_chain_display(LOG_LVL_INFO,
+                                       "tap/device found",
                                        tap->dotted_name, idcode);
 
                        bit_count += 32;
@@ -1033,7 +1071,7 @@ static int jtag_examine_chain(void)
 
                /* ensure the TAP ID matches what was expected */
                if (!jtag_examine_chain_match_tap(tap))
-                       return ERROR_JTAG_INIT_FAILED;
+                       retval = ERROR_JTAG_INIT_SOFT_FAIL;
        }
 
        /* Fail if too many TAPs were enabled for us to verify them all. */
@@ -1049,11 +1087,14 @@ static int jtag_examine_chain(void)
        if (jtag_examine_chain_end(idcode_buffer, bit_count,
                        8 * sizeof(idcode_buffer))) {
                LOG_ERROR("double-check your JTAG setup (interface, "
-                               "speed, TAPs, ...)");
+                               "speed, missing TAPs, ...)");
                return ERROR_JTAG_INIT_FAILED;
        }
 
-       return ERROR_OK;
+       /* Return success or, for backwards compatibility if only
+        * some IDCODE values mismatched, a soft/continuable fault.
+        */
+       return retval;
 }
 
 /*
@@ -1255,18 +1296,37 @@ int jtag_init_inner(struct command_context_s *cmd_ctx)
        if ((retval = jtag_execute_queue()) != ERROR_OK)
                return retval;
 
-       /* examine chain first, as this could discover the real chain layout */
-       if (jtag_examine_chain() != ERROR_OK)
-       {
+       /* Examine DR values first.  This discovers problems which will
+        * prevent communication ... hardware issues like TDO stuck, or
+        * configuring the wrong number of (enabled) TAPs.
+        */
+       retval = jtag_examine_chain();
+       switch (retval) {
+       case ERROR_OK:
+               /* complete success */
+               break;
+       case ERROR_JTAG_INIT_SOFT_FAIL:
+               /* For backward compatibility reasons, try coping with
+                * configuration errors involving only ID mismatches.
+                * We might be able to talk to the devices.
+                */
                LOG_ERROR("Trying to use configured scan chain anyway...");
                issue_setup = false;
+               break;
+       default:
+               /* some hard error; already issued diagnostics */
+               return retval;
        }
 
-       if (jtag_validate_ircapture() != ERROR_OK)
-       {
-               LOG_WARNING("Errors during IR capture, continuing anyway...");
-               issue_setup = false;
-       }
+       /* Now look at IR values.  Problems here will prevent real
+        * communication.  They mostly mean that the IR length is
+        * wrong ... or that the IR capture value is wrong.  (The
+        * latter is uncommon, but easily worked around:  provide
+        * ircapture/irmask values during TAP setup.)
+        */
+       retval = jtag_validate_ircapture();
+       if (retval != ERROR_OK)
+               return retval;
 
        if (issue_setup)
                jtag_notify_event(JTAG_TAP_EVENT_SETUP);