lib/cmsis_rtos_v1: Implement support for semaphore APIs

These APIs allow creating, acquiring, releasing and deleting
of semaphores.

Signed-off-by: Rajavardhan Gundi <rajavardhan.gundi@intel.com>

lib/cmsis_rtos_v1/CMakeLists.txt

@@ -11,6 +11,7 @@ zephyr_library_sources_ifdef(
   cmsis_kernel.c
   cmsis_timer.c
   cmsis_mutex.c
+  cmsis_semaphore.c
 )
 
 zephyr_library_link_libraries(CMSIS)

lib/cmsis_rtos_v1/Kconfig

@@ -46,6 +46,14 @@ config CMSIS_MUTEX_MAX_COUNT
 	help
 	  Mention maximum number of mutexes in CMSIS compliant application.
 
+config CMSIS_SEMAPHORE_MAX_COUNT
+	int
+	prompt "Maximum semaphore count in CMSIS application"
+	default 5
+	range 0 255
+	help
+	  Mention maximum number of semaphores in CMSIS compliant application.
+
 config NUM_PREEMPT_PRIORITIES
 	int
 	default 7

lib/cmsis_rtos_v1/cmsis_semaphore.c

@@ -0,0 +1,121 @@
+/*
+ * Copyright (c) 2018 Intel Corporation
+ *
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+#include <kernel_structs.h>
+#include <cmsis_os.h>
+
+K_MEM_SLAB_DEFINE(cmsis_semaphore_slab, sizeof(struct k_sem),
+		CONFIG_CMSIS_SEMAPHORE_MAX_COUNT, 4);
+
+/**
+ * @brief Create and Initialize a semaphore object.
+ */
+osSemaphoreId osSemaphoreCreate(const osSemaphoreDef_t *semaphore_def,
+				int32_t count)
+{
+	struct k_sem *semaphore;
+
+	if (semaphore_def == NULL) {
+		return NULL;
+	}
+
+	if (_is_in_isr()) {
+		return NULL;
+	}
+
+	if (k_mem_slab_alloc(&cmsis_semaphore_slab,
+				(void **)&semaphore, 100) == 0) {
+		memset(semaphore, 0, sizeof(struct k_sem));
+	} else {
+		return NULL;
+	}
+
+	k_sem_init(semaphore, count, count);
+
+	return (osSemaphoreId)semaphore;
+}
+
+/**
+ * @brief Wait until a semaphore becomes available.
+ */
+int32_t osSemaphoreWait(osSemaphoreId semaphore_id, uint32_t timeout)
+{
+	struct k_sem *semaphore = (struct k_sem *) semaphore_id;
+	int status;
+
+	if (semaphore_id == NULL) {
+		return -1;
+	}
+
+	if (_is_in_isr()) {
+		return -1;
+	}
+
+	if (timeout == osWaitForever) {
+		status = k_sem_take(semaphore, K_FOREVER);
+	} else if (timeout == 0) {
+		status = k_sem_take(semaphore, K_NO_WAIT);
+	} else {
+		status = k_sem_take(semaphore, timeout);
+	}
+
+	/* If k_sem_take is successful, return the number of available
+	 * tokens + 1. +1 is for accounting the currently acquired token.
+	 * If it has timed out, return 0 (no tokens available).
+	 */
+	if (status == 0) {
+		return k_sem_count_get(semaphore) + 1;
+	} else if (status == -EAGAIN) {
+		return 0;
+	}
+
+	return -1;
+}
+
+/**
+ * @brief Release a semaphore that was obtained by osSemaphoreWait.
+ */
+osStatus osSemaphoreRelease(osSemaphoreId semaphore_id)
+{
+	struct k_sem *semaphore = (struct k_sem *) semaphore_id;
+
+	if (semaphore_id == NULL) {
+		return osErrorParameter;
+	}
+
+	/* All tokens have already been released */
+	if (k_sem_count_get(semaphore) == semaphore->limit) {
+		return osErrorResource;
+	}
+
+	k_sem_give(semaphore);
+
+	return osOK;
+}
+
+/**
+ * @brief Delete a semaphore that was created by osSemaphoreCreate.
+ */
+osStatus osSemaphoreDelete(osSemaphoreId semaphore_id)
+{
+	struct k_sem *semaphore = (struct k_sem *) semaphore_id;
+
+	if (semaphore_id == NULL) {
+		return osErrorParameter;
+	}
+
+	if (_is_in_isr()) {
+		return osErrorISR;
+	}
+
+	/* The status code "osErrorResource" (the semaphore object
+	 * could not be deleted) is not supported in Zephyr.
+	 */
+
+	k_mem_slab_free(&cmsis_semaphore_slab, (void *) &semaphore);
+
+	return osOK;
+}