fix enter debug mode for locking

added an alternative way to enter debug mode, which does not require restarting the chip.
this will not always work, but in general it will (failure 0.3%), and failure is not a dramatic issue, simply have to use the full sequence.
the user can only access "halt", which uses the full sequence, so the user should not have any problems.
restarting the chip requires reconfiguring the flash module. the doc is very poor, so i'd rather have the two methods, and live with the 0.3%.

src/target/dsp5680xx.c

@@ -524,9 +524,9 @@ static int eonce_enter_debug_mode(struct target * target, uint16_t * eonce_statu
     err_check(retval,"Failed to get master tap.");
   }
 
-  tap_chp->enabled = false;
+  // Enable master tap
-  retval = switch_tap(target,tap_chp,tap_cpu);
+  tap_chp->enabled = true;
-  err_check_propagate(retval);
+  tap_cpu->enabled = false;
 
   instr = MASTER_TAP_CMD_IDCODE;
   retval =  dsp5680xx_irscan(target, & instr, & ir_out,DSP5680XX_JTAG_MASTER_TAP_IRLEN);
@@ -542,6 +542,7 @@ static int eonce_enter_debug_mode(struct target * target, uint16_t * eonce_statu
   // ir_out now hold tap idcode
 
   // Enable core tap
+  tap_chp->enabled = true;
   retval = switch_tap(target,tap_chp,tap_cpu);
   err_check_propagate(retval);
 
@@ -591,6 +592,52 @@ static int eonce_enter_debug_mode(struct target * target, uint16_t * eonce_statu
   return retval;
 }
 
+/** 
+ * Puts the core into debug mode, enabling the EOnCE module.
+ * This will not always work, eonce_enter_debug_mode executes much
+ * more complicated routine, which is guaranteed to work, but requires
+ * a reset. This will complicate comm with the flash module, since
+ * after a reset clock divisors must be set again.
+ * This implementation works most of the time, and is not accesible to the
+ * user.
+ * 
+ * @param target 
+ * @param eonce_status Data read from the EOnCE status register.
+ * 
+ * @return 
+ */
+static int eonce_enter_debug_mode_without_reset(struct target * target, uint16_t * eonce_status){
+  int retval;
+  uint32_t instr = JTAG_INSTR_DEBUG_REQUEST;
+  uint32_t ir_out;//not used, just to make jtag happy.
+  // Debug request #1
+  retval = dsp5680xx_irscan(target,& instr,& ir_out,DSP5680XX_JTAG_CORE_TAP_IRLEN);
+  err_check_propagate(retval);
+
+  // Enable EOnCE module
+  instr = JTAG_INSTR_ENABLE_ONCE;
+  //Two rounds of jtag 0x6  (enable eonce) to enable EOnCE.
+  retval =  dsp5680xx_irscan(target, & instr, & ir_out,DSP5680XX_JTAG_CORE_TAP_IRLEN);
+  err_check_propagate(retval);
+  retval =  dsp5680xx_irscan(target, & instr, & ir_out,DSP5680XX_JTAG_CORE_TAP_IRLEN);
+  err_check_propagate(retval);
+  // Verify that debug mode is enabled
+  uint16_t data_read_from_dr;
+  retval = eonce_read_status_reg(target,&data_read_from_dr);
+  err_check_propagate(retval);
+  if((data_read_from_dr&0x30) == 0x30){
+    LOG_DEBUG("EOnCE successfully entered debug mode.");
+    target->state = TARGET_HALTED;
+    retval = ERROR_OK;
+  }else{
+    retval = ERROR_TARGET_FAILURE;
+    err_check(retval,"Failed to set EOnCE module to debug mode. Try with halt");
+  }
+  if(eonce_status!=NULL)
+    *eonce_status = data_read_from_dr;
+  return ERROR_OK;
+}
+
 /** 
  * Reads the current value of the program counter and stores it.
  * 
@@ -1316,12 +1363,7 @@ static int dsp5680xx_f_signature(struct target * target, uint32_t address, uint3
   int retval;
   uint16_t hfm_ustat;
   if (dsp5680xx_target_status(target,NULL,NULL) != TARGET_HALTED){
-    retval = eonce_enter_debug_mode(target,NULL);
+    retval = eonce_enter_debug_mode_without_reset(target,NULL);
-    err_check_propagate(retval);
-    // -- -- -- -- -- -- -- -- -- -- -- -- -- -- --
-    // Set hfmdiv
-    // -- -- -- -- -- -- -- -- -- -- -- -- -- -- --
-    retval = set_fm_ck_div(target);
     err_check_propagate(retval);
   }
   retval = dsp5680xx_f_execute_command(target,HFM_CALCULATE_DATA_SIGNATURE,address,words,&hfm_ustat,1);
@@ -1590,7 +1632,6 @@ int dsp5680xx_f_unlock(struct target * target){
   retval = eonce_enter_debug_mode(target,&eonce_status);
   if(retval == ERROR_OK){
     LOG_WARNING("Memory was not locked.");
-    return retval;
   }
   
   jtag_add_reset(0,1);
@@ -1613,6 +1654,7 @@ int dsp5680xx_f_unlock(struct target * target){
   usleep(TIME_DIV_FREESCALE*300*1000);
 
   // Enable master tap
+  tap_chp->enabled = false;
   retval = switch_tap(target,tap_chp,tap_cpu);
   err_check_propagate(retval);
 
@@ -1667,10 +1709,10 @@ int dsp5680xx_f_unlock(struct target * target){
 
 int dsp5680xx_f_lock(struct target * target){
   int retval;
-  uint16_t lock_word[] = {HFM_LOCK_FLASH,HFM_LOCK_FLASH};
+  uint16_t lock_word[] = {HFM_LOCK_FLASH};
-  retval = dsp5680xx_f_wr(target,(uint8_t *)(lock_word),HFM_LOCK_ADDR_L,4,1);
+  retval = dsp5680xx_f_wr(target,(uint8_t *)(lock_word),HFM_LOCK_ADDR_L,2,1);
   err_check_propagate(retval);
-  return retval;
+
   jtag_add_reset(0,1);
   usleep(TIME_DIV_FREESCALE*200*1000);