Add support for the tracing infastructure in coreboot.

The compiler is forced to emmit special functions on every
entry/exit of the function. Add a compile time option
to support it. Function entries will be printed in
the console. The CONFIG_TRACE has more documentation.

Patch for userspace tools will follow.

Change-Id: I2cbeb3f104892b034c8756f86ed05bf71187c3f3
Signed-off-by: Rudolf Marek <r.marek@assembler.cz>
Reviewed-on: http://review.coreboot.org/178
Tested-by: build bot (Jenkins)
Reviewed-by: Stefan Reinauer <stefan.reinauer@coreboot.org>

src/lib/trace.c

@@ -0,0 +1,39 @@
+/*
+ * This file is part of the coreboot project.
+ *
+ * Copyright (C) 2011 Rudolf Marek <r.marek@assembler.cz>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; version 2 of the License.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301 USA
+ */
+
+#include <types.h>
+#include <console/console.h>
+#include <trace.h>
+
+int volatile trace_dis = 0;
+
+void __cyg_profile_func_enter( void *func, void *callsite)
+{
+
+	if (trace_dis)
+		return;
+
+	DISABLE_TRACE
+	printk(BIOS_INFO, "~0x%08x(0x%08x)\n", (uint32_t) func, (uint32_t) callsite);
+	ENABLE_TRACE
+}
+
+void __cyg_profile_func_exit( void *func, void *callsite )
+{
+}