建立工程，成功创建两个虚拟串口

source/OpenAMP/libmetal/lib/system/linux/mutex.h

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+/*
+ * Copyright (c) 2015, Xilinx Inc. and Contributors. All rights reserved.
+ *
+ * SPDX-License-Identifier: BSD-3-Clause
+ */
+
+/*
+ * @file	linux/mutex.h
+ * @brief	Linux mutex primitives for libmetal.
+ */
+
+#ifndef __METAL_MUTEX__H__
+#error "Include metal/mutex.h instead of metal/linux/mutex.h"
+#endif
+
+#ifndef __METAL_LINUX_MUTEX__H__
+#define __METAL_LINUX_MUTEX__H__
+
+#include <unistd.h>
+#include <sys/syscall.h>
+#include <linux/futex.h>
+
+#include <metal/atomic.h>
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+typedef struct {
+	atomic_int v;
+} metal_mutex_t;
+
+/*
+ * METAL_MUTEX_INIT - used for initializing an mutex elmenet in a static struct
+ * or global
+ */
+#define METAL_MUTEX_INIT(m) { ATOMIC_VAR_INIT(0) }
+/*
+ * METAL_MUTEX_DEFINE - used for defining and initializing a global or
+ * static singleton mutex
+ */
+#define METAL_MUTEX_DEFINE(m) metal_mutex_t m = METAL_MUTEX_INIT(m)
+
+static inline int __metal_mutex_cmpxchg(metal_mutex_t *mutex,
+					int exp, int val)
+{
+	atomic_compare_exchange_strong(&mutex->v, (int *)&exp, val);
+	return exp;
+}
+
+static inline void __metal_mutex_init(metal_mutex_t *mutex)
+{
+	atomic_store(&mutex->v, 0);
+}
+
+static inline void __metal_mutex_deinit(metal_mutex_t *mutex)
+{
+	(void)mutex;
+}
+
+static inline int __metal_mutex_try_acquire(metal_mutex_t *mutex)
+{
+	int val = 0;
+	return atomic_compare_exchange_strong(&mutex->v, &val, 1);
+}
+
+static inline void __metal_mutex_acquire(metal_mutex_t *mutex)
+{
+	int c = 0;
+
+	if (atomic_compare_exchange_strong(&mutex->v, &c, 1))
+		return;
+	if (c != 2)
+		c = atomic_exchange(&mutex->v, 2);
+	while (c != 0) {
+		syscall(SYS_futex, &mutex->v, FUTEX_WAIT, 2, NULL, NULL, 0);
+		c = atomic_exchange(&mutex->v, 2);
+	}
+}
+
+static inline void __metal_mutex_release(metal_mutex_t *mutex)
+{
+	if (atomic_fetch_sub(&mutex->v, 1) != 1) {
+		atomic_store(&mutex->v, 0);
+		syscall(SYS_futex, &mutex->v, FUTEX_WAKE, 1, NULL, NULL, 0);
+	}
+}
+
+static inline int __metal_mutex_is_acquired(metal_mutex_t *mutex)
+{
+	return atomic_load(&mutex->v);
+}
+
+#ifdef __cplusplus
+}
+#endif
+
+#endif /* __METAL_LINUX_MUTEX__H__ */