nios2: fatal: add _SysFatalErrorHandler and _Fault stub

ZEP-252 will handle implementation of the code here.

Change-Id: I3e9a6c7cdf2d5a3b0240317b772628fead528095
Signed-off-by: Andrew Boie <andrew.p.boie@intel.com>

arch/nios2/core/fatal.c

@@ -17,18 +17,77 @@
 #include <nanokernel.h>
 #include <arch/cpu.h>
 #include <nano_private.h>
+#include <misc/printk.h>
 
+/* TODO initialize with sentinel values */
 const NANO_ESF _default_esf;
 
+
+/**
+ *
+ * @brief Nanokernel fatal error handler
+ *
+ * This routine is called when a fatal error condition is detected by either
+ * hardware or software.
+ *
+ * The caller is expected to always provide a usable ESF.  In the event that the
+ * fatal error does not have a hardware generated ESF, the caller should either
+ * create its own or call _Fault instead.
+ *
+ * @param reason the reason that the handler was called
+ * @param pEsf pointer to the exception stack frame
+ *
+ * @return This function does not return.
+ */
 FUNC_NORETURN void _NanoFatalErrorHandler(unsigned int reason,
 					  const NANO_ESF *esf)
 {
-	ARG_UNUSED(reason);
+	/* STUB TODO: dump out reason for the error and any interesting
-	ARG_UNUSED(esf);
+	 * info in esf
+	 */
+
+	_SysFatalErrorHandler(reason, esf);
+}
+
+
+
+FUNC_NORETURN void _Fault(void)
+{
+	/* STUB TODO dump out reason for this exception */
+
+	_NanoFatalErrorHandler(_NANO_ERR_HW_EXCEPTION, &_default_esf);
+}
+
+/**
+ *
+ * @brief Fatal error handler
+ *
+ * This routine implements the corrective action to be taken when the system
+ * detects a fatal error.
+ *
+ * This sample implementation attempts to abort the current thread and allow
+ * the system to continue executing, which may permit the system to continue
+ * functioning with degraded capabilities.
+ *
+ * System designers may wish to enhance or substitute this sample
+ * implementation to take other actions, such as logging error (or debug)
+ * information to a persistent repository and/or rebooting the system.
+ *
+ * @param reason the fatal error reason
+ * @param pEsf the pointer to the exception stack frame
+ *
+ * @return This function does not return.
+ */
+FUNC_NORETURN void _SysFatalErrorHandler(unsigned int reason,
+					 const NANO_ESF *esf)
+{
+	/* STUB TODO try to abort task/fibers like in the x86 implementation */
+	printk("Fatal error!\n");
 
-	/* STUB */
 	while (1) {
 		/* whee! */
 	}
 }
 
+
+

include/arch/nios2/arch.h

@@ -70,6 +70,9 @@ struct __esf {
 typedef struct __esf NANO_ESF;
 extern const NANO_ESF _default_esf;
 
+FUNC_NORETURN void _SysFatalErrorHandler(unsigned int reason,
+					 const NANO_ESF *esf);
+
 #endif /* _ASMLANGUAGE */
 
 #ifdef __cplusplus