kernel: POSIX: Compatibility layer for POSIX clock APIs.

This patch provides POSIX clock APIs for POSIX 1003.1 PSE52 standard.

Signed-off-by: Youvedeep Singh <youvedeep.singh@intel.com>

Author: youvedeep-singh

arch/posix/include/posix_cheats.h

@@ -31,6 +31,8 @@
 #define pthread_barrier_t      zap_pthread_barrier_t
 #define pthread_barrierattr_t  zap_pthread_barrierattr_t
 #define pthread_attr_t         zap_pthread_attr_t
+#define clockid_t              zap_clockid_t
+#define sched_param            zap_sched_param
 
 /* Condition variables */
 #define pthread_cond_init(...)        zap_pthread_cond_init(__VA_ARGS__)
@@ -99,6 +101,10 @@
 #define sleep(...)			zap_sleep(__VA_ARGS__)
 #define usleep(...)			zap_usleep(__VA_ARGS__)
 
+/* Clock */
+#define clock_gettime(...)		zap_clock_gettime(__VA_ARGS__)
+#define clock_settime(...)		zap_clock_settime(__VA_ARGS__)
+
 #endif /* CONFIG_ARCH_POSIX */
 
 #endif

include/posix/pthread.h

@@ -8,18 +8,7 @@
 #define __PTHREAD_H__
 
 #include <kernel.h>
-#ifdef CONFIG_NEWLIB_LIBC
 #include <time.h>
-#else
-/* This should probably live somewhere else but Zephyr doesn't
- * currently have a stdc layer to provide it
- */
-struct timespec {
-	s32_t tv_sec;
-	s32_t tv_nsec;
-};
-#endif	/* CONFIG_NEWLIB_LIBC */
-
 #include "sys/types.h"
 #include "posix_sched.h"
 #include "unistd.h"
@@ -63,11 +52,6 @@ struct posix_thread {
 #define PTHREAD_CANCEL_ENABLE	(0 << _PTHREAD_CANCEL_POS)
 #define PTHREAD_CANCEL_DISABLE	(1 << _PTHREAD_CANCEL_POS)
 
-static inline s32_t _ts_to_ms(const struct timespec *to)
-{
-	return (to->tv_sec * 1000) + (to->tv_nsec / 1000000);
-}
-
 /**
  * @brief Declare a pthread condition variable
  *

include/posix/sys/types.h

@@ -7,14 +7,14 @@
 #ifndef __POSIX_TYPES_H__
 #define __POSIX_TYPES_H__
 
-
 #ifdef __cplusplus
 extern "C" {
 #endif
 
 #include_next <sys/types.h>
 
 #ifdef CONFIG_PTHREAD_IPC
+#include <kernel.h>
 
 /* Thread attributes */
 typedef struct pthread_attr_t {
@@ -60,6 +60,9 @@ typedef struct pthread_barrierattr {
 } pthread_barrierattr_t;
 
 /* time related attributes */
+#ifndef CONFIG_NEWLIB_LIBC
+typedef u32_t clockid_t;
+#endif /*CONFIG_NEWLIB_LIBC */
 typedef unsigned long useconds_t;
 
 #endif /* CONFIG_PTHREAD_IPC */

include/posix/time.h

@@ -0,0 +1,49 @@
+/*
+ * Copyright (c) 2018 Intel Corporation
+ *
+ * SPDX-License-Identifier: Apache-2.0
+ */
+#ifndef __POSIX_TIME_H__
+#define __POSIX_TIME_H__
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+#ifdef CONFIG_NEWLIB_LIBC
+#include_next <time.h>
+#else
+struct timespec {
+	s32_t tv_sec;
+	s32_t tv_nsec;
+};
+#endif /* CONFIG_NEWLIB_LIBC */
+#include <kernel.h>
+#include <errno.h>
+#include "sys/types.h"
+
+#define CLOCK_MONOTONIC 1
+
+static inline s32_t _ts_to_ms(const struct timespec *to)
+{
+	return (to->tv_sec * 1000) + (to->tv_nsec / 1000000);
+}
+
+/**
+ * @brief Set clock time.
+ *
+ * See IEEE 1003.1
+ */
+static inline int clock_settime(clockid_t clock_id, const struct timespec *ts)
+{
+	errno = ENOSYS;
+	return -1;
+}
+
+int clock_gettime(clockid_t clock_id, struct timespec *ts);
+
+#ifdef __cplusplus
+}
+#endif
+
+#endif /* __POSIX_TIME_H__ */

kernel/posix/CMakeLists.txt

@@ -4,3 +4,4 @@ target_sources(kernel PRIVATE posix/pthread_mutex.c)
 target_sources(kernel PRIVATE posix/pthread_barrier.c)
 target_sources(kernel PRIVATE posix/pthread.c)
 target_sources(kernel PRIVATE posix/pthread_sched.c)
+target_sources(kernel PRIVATE posix/clock.c)

kernel/posix/clock.c

@@ -0,0 +1,36 @@
+/*
+ * Copyright (c) 2018 Intel Corporation
+ *
+ * SPDX-License-Identifier: Apache-2.0
+ */
+#include <kernel.h>
+#include <time.h>
+#include <errno.h>
+
+/**
+ * @brief Get clock time specified by clock_id.
+ *
+ * See IEEE 1003.1
+ */
+int clock_gettime(clockid_t clock_id, struct timespec *ts)
+{
+	s64_t elapsed_msecs, elapsed_secs;
+	s64_t elapsed_nsec, elapsed_cycles;
+
+	if (clock_id != CLOCK_MONOTONIC) {
+		errno = EINVAL;
+		return -1;
+	}
+
+	elapsed_msecs = k_uptime_get();
+	elapsed_secs = elapsed_msecs / MSEC_PER_SEC;
+
+	elapsed_cycles = (s64_t) (k_cycle_get_32() %
+				  sys_clock_hw_cycles_per_sec);
+	elapsed_nsec = (s64_t) ((elapsed_cycles * NSEC_PER_SEC) /
+				sys_clock_hw_cycles_per_sec);
+
+	ts->tv_sec = (s32_t) elapsed_secs;
+	ts->tv_nsec = (s32_t) elapsed_nsec;
+	return 0;
+}