nds32: support multi-target debugging

Change-Id: If767f646b234dbcdb01946e5d13a3a6a29df2d78
Signed-off-by: Hsiangkai Wang <hsiangkai@gmail.com>
Reviewed-on: http://openocd.zylin.com/1581
Tested-by: jenkins
Reviewed-by: Spencer Oliver <spen@spen-soft.co.uk>

src/target/nds32.h

@@ -296,6 +296,8 @@ struct nds32 {
 	/** Record syscall ID for other operations to do special processing for target */
 	int active_syscall_id;
 
+	struct breakpoint syscall_break;
+
 	/** Flag reporting whether global stop is active. */
 	bool global_stop;
 
@@ -309,6 +311,9 @@ struct nds32 {
 	 * handler, it should be true. */
 	bool keep_target_edm_ctl;
 
+	/* Value of $EDM_CTL before target enters debug mode */
+	uint32_t backup_edm_ctl;
+
 	/** always use word-aligned address to access memory */
 	bool word_access_mem;
 
@@ -346,6 +351,9 @@ struct nds32 {
 	 *  hardware breakpoints or not in ROM */
 	bool auto_convert_hw_bp;
 
+	/* Flag to indicate the target is attached by debugger or not */
+	bool attached;
+
 	/** Backpointer to the target. */
 	struct target *target;