armv7m: add generic trace support (TPIU, ITM, etc.)

This provides support for various trace-related subsystems in a
generic and expandable way.

Change-Id: I3a27fa7b8cfb111753088bb8c3d760dd12d1395f
Signed-off-by: Paul Fertser <fercerpav@gmail.com>
Reviewed-on: http://openocd.zylin.com/2538
Tested-by: jenkins

src/target/cortex_m.c

@@ -1932,6 +1932,16 @@ int cortex_m_examine(struct target *target)
 			armv7m->dap.tar_autoincr_block = (1 << 12);
 		}
 
+		/* Configure trace modules */
+		retval = target_write_u32(target, DCB_DEMCR, TRCENA | armv7m->demcr);
+		if (retval != ERROR_OK)
+			return retval;
+
+		if (armv7m->trace_config.config_type != DISABLED) {
+			armv7m_trace_tpiu_config(target);
+			armv7m_trace_itm_config(target);
+		}
+
 		/* NOTE: FPB and DWT are both optional. */
 
 		/* Setup FPB */
@@ -2324,6 +2334,9 @@ static const struct command_registration cortex_m_command_handlers[] = {
 	{
 		.chain = armv7m_command_handlers,
 	},
+	{
+		.chain = armv7m_trace_command_handlers,
+	},
 	{
 		.name = "cortex_m",
 		.mode = COMMAND_EXEC,