Make ASSERT() report assertion failures

Rather than just reset the board, report assertion failures to aid
debugging. To enable this, use CONFIG_ASSERT_HELP.

BUG=chrome-os-partner:10149
TEST=manual
Enable the option for snow, add a failing ASSERT() to the rw command
and see the a nice message is printed now.

ASSERTION FAILURE 'address' in command_read_word() at common/memory_commands.c:00000037

Change-Id: Ice59434c5daf610832dd0e1fcfa5630dc847bb67
Signed-off-by: Simon Glass <sjg@chromium.org>
Reviewed-on: https://gerrit.chromium.org/gerrit/25411

README

@@ -54,3 +54,9 @@ Build Options
 	Precise data bus error, Forced hard fault, Vector catch, bfar = 60000000
 	mmfs = 00008200, shcsr = 00000000, hfsr = 40000000, dfsr = 00000008
 
+- CONFIG_ASSERT_HELP
+
+	Report assertion failures in a vebose manner to aid debugging. When
+	enabled an ASSERT() which fails will produce message in the form:
+
+		ASSERTION FAILURE '<expr>' in function() at file:line

core/cortex-m/panic.c

@@ -360,3 +360,15 @@ void exception_panic(void)
 			[save_area] "r" (save_area.saved_regs)
 		);
 }
+
+
+#ifdef CONFIG_ASSERT_HELP
+void panic_assert_fail(const char *msg, const char *func, const char *fname,
+		       int linenum)
+{
+	panic_printf("\nASSERTION FAILURE '%s' in %s() at %s:%d\n", msg, func,
+		     fname, linenum);
+
+	panic_reboot();
+}
+#endif

include/panic.h

@@ -56,6 +56,18 @@ void panic_vprintf(const char *format, va_list args);
  */
 void panic_printf(const char *format, ...);
 
+
+/**
+ * Report an assertion failure and reset
+ *
+ * @param msg		Assertion expression or other message
+ * @param func		Function name where assertion happened
+ * @param fname		File name where assertion happened
+ * @param linenum	Line number where assertion happened
+ */
+void panic_assert_fail(const char *msg, const char *func, const char *fname,
+		       int linenum);
+
 /**
  * Report a panic to the panic reporting device
  *

include/util.h

@@ -10,6 +10,7 @@
 
 #include "common.h"
 #include "config.h"
+#include "panic.h"
 
 /**
  * Trigger a compilation failure if the condition
@@ -22,10 +23,18 @@
  * is not verified at runtime.
  */
 #ifdef CONFIG_DEBUG
-#define ASSERT(cond) do {			\
+# ifdef CONFIG_ASSERT_HELP
+#  define ASSERT(cond) do {			\
+		if (!(cond))			\
+			panic_assert_fail(#cond, __func__, __FILE__, \
+				__LINE__);	\
+	} while (0);
+# else
+#  define ASSERT(cond) do {			\
 		if (!(cond))			\
 			__asm("bkpt");		\
 	} while (0);
+# endif
 #else
 #define ASSERT(cond)
 #endif