Add static allocation of RTOS objects for CMSIS-RTOSv2 API port

[utsavm9]

Introduction

When creating Zephyr RTOS objects like mutex, timers or message queues via CMSIS-RTOSv2 API, there are two options for the users to choose - dynamic allocation or RTOS implementation-specific static allocation. Dynamic allocation is what's currently supported by Zephyr portability layer with static allocation left unimplemented.

• CMSIS-RTOSv2 reference: Memory Management
• CMSIS-RTOSv2 reference: Static Object Memory

Problem description

It is a hassle to keep a track of how many RTOS objects a project might be using. With dynamic allocation, we need to declare this via configs like CONFIG_CMSIS_V2_MUTEX_MAX_COUNT. Either memory is getting wasted by allocating huge pools which are not fully used, or these configs need manual update as different libraries get added/removed to a project.

Proposed change

The above will not be a problem if Zephyr's CMSIS-RTOSv2 port supports static memory allocation. I plan on

• Make types in subsys/portability/cmsis_rtos_v2/wrapper.h available to users by moving it to <zephyr/portability/cmsis_os2_types.h>.
• Support passing in struct cv2_mutex equivalent types in .cb_mem field of CMSIS-RTOSv2 osxxxAttr_t objects. If the projects passes in cv2_mutex object, when Zephyr portability layer would not need to allocate this object from a buffer.

Dependencies

This would not impact existing use of dynamic allocation for creating RTOS objects via CMSIS-RTOSv2.

Concerns and Unresolved Questions

Let me know of any concerns or ideas, otherwise I am creating a pull request implementing this proposal.

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