nios2: implement kernel_event_logger

Interrupts and context switches are logged. Since this CPU does not
have a power-saving instruction, it never enters a sleep state so
we do not call _sys_k_event_logger_enter_sleep() from anywhere.

Change-Id: Idcef388e93ffea373446997a0f87e93a4db44331
Signed-off-by: Andrew Boie <andrew.p.boie@intel.com>

arch/nios2/include/kernel_event_logger_arch.h

@@ -0,0 +1,51 @@
+/*
+ * Copyright (c) 2016 Intel Corporation
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+/**
+ * @file
+ * @brief Kernel event logger support for Nios II
+ */
+
+#ifndef __KERNEL_EVENT_LOGGER_ARCH_H__
+#define __KERNEL_EVENT_LOGGER_ARCH_H__
+
+#include <arch/cpu.h>
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+/**
+ * @brief Get the identification of the current interrupt.
+ *
+ * This routine obtain the key of the interrupt that is currently processed
+ * if it is called from a ISR context.
+ *
+ * @return The key of the interrupt that is currently being processed.
+ */
+static inline int _sys_current_irq_key_get(void)
+{
+	uint32_t ipending;
+
+	ipending = _nios2_creg_read(NIOS2_CR_IPENDING);
+	return find_lsb_set(ipending) - 1;
+}
+
+#ifdef __cplusplus
+}
+#endif
+
+#endif /* __KERNEL_EVENT_LOGGER_ARCH_H__ */