105 lines
2.8 KiB
C
105 lines
2.8 KiB
C
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/*
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* Copyright (c) 2010-2015 Wind River Systems, Inc.
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* Copyright (c) 2017 Oticon A/S
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*
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* SPDX-License-Identifier: Apache-2.0
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*/
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/**
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* @file
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* @brief Kernel swapper code for POSIX
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*
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* This module implements the __swap() routine for the POSIX architecture.
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*
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*/
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#include "kernel.h"
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#include <kernel_structs.h>
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#include "posix_core.h"
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#include "irq.h"
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/**
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*
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* @brief Initiate a cooperative context switch
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*
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* The __swap() routine is invoked by various kernel services to effect
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* a cooperative context switch. Prior to invoking __swap(), the
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* caller disables interrupts (via irq_lock) and the return 'key'
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* is passed as a parameter to __swap().
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*
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*
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* @return -EAGAIN, or a return value set by a call to
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* _set_thread_return_value()
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*
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*/
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unsigned int __swap(unsigned int key)
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{
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/*
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* struct k_thread * _kernel.current is the currently runnig thread
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* struct k_thread * _kernel.ready_q.cache contains the next thread to run
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* (cannot be NULL)
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*
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* Here a "real" arch would save all processor registers, stack pointer and so
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* forth.
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* But we do not need to do so because we use posix threads => those are all
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* nicely kept by the native OS kernel
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*/
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_kernel.current->callee_saved.key = key;
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_kernel.current->callee_saved.retval = -EAGAIN;
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/* retval may be modified with a call to _set_thread_return_value() */
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#if CONFIG_KERNEL_EVENT_LOGGER_CONTEXT_SWITCH
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_sys_k_event_logger_context_switch();
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#endif
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posix_thread_status_t *ready_thread_ptr =
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(posix_thread_status_t *)
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_kernel.ready_q.cache->callee_saved.thread_status;
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posix_thread_status_t *this_thread_ptr =
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(posix_thread_status_t *)
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_kernel.current->callee_saved.thread_status;
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_kernel.current = _kernel.ready_q.cache;
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/*
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* Here a "real" arch would load all processor registers for the thread
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* to run. In this arch case, we just block this thread until allowed to
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* run later, and signal to whomever is allowed to run to continue.
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*/
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posix_swap(ready_thread_ptr->thread_idx,
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this_thread_ptr->thread_idx);
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/* When we continue, _kernel->current points back to this thread */
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irq_unlock(_kernel.current->callee_saved.key);
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return _kernel.current->callee_saved.retval;
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}
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#ifdef CONFIG_ARCH_HAS_CUSTOM_SWAP_TO_MAIN
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/**
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* This is just a version of __swap() in which we do not save anything about the
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* current thread.
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*
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* Note that we will never come back to this thread:
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* posix_core_main_thread_start() does never return
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*/
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void _arch_switch_to_main_thread(struct k_thread *main_thread,
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k_thread_stack_t *main_stack,
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size_t main_stack_size, k_thread_entry_t _main)
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{
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posix_thread_status_t *ready_thread_ptr =
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(posix_thread_status_t *)
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_kernel.ready_q.cache->callee_saved.thread_status;
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_kernel.current = _kernel.ready_q.cache;
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posix_main_thread_start(ready_thread_ptr->thread_idx);
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}
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#endif
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