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677d690e2b
Fixes #1708. Currently involuntary preemption causes the current thread not only to yield for a higher prioritized thread, but all other threads of its own priority class, too. This PR adds the function `thread_yield_higher()`, which will yield the current thread in favor of higher prioritized functions, but not for threads of its own priority class. Boards now need to implement `thread_yield_higher()` instead of `thread_yield()`, but `COREIF_NG` boards are not affected in any way. `thread_yield()` retains its old meaning: yield for every thread that has the same or a higher priority. This PR does not touch the occurrences of `thread_yield()` in the periph drivers, because the author of this PR did not look into the logic of the various driver implementations.
120 lines
2.9 KiB
C
120 lines
2.9 KiB
C
/*
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* Copyright (C) 2014, Freie Universitaet Berlin (FUB) & INRIA.
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* All rights reserved.
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*
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* This file is subject to the terms and conditions of the GNU Lesser
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* General Public License v2.1. See the file LICENSE in the top level
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* directory for more details.
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*/
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#include "cpu.h"
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#include "irq.h"
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#include "kernel.h"
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#include "kernel_internal.h"
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#include "sched.h"
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#include "thread.h"
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volatile int __inISR = 0;
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char __isr_stack[MSP430_ISR_STACK_SIZE];
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/*
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* we must prevent the compiler to generate a prologue or an epilogue
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* for thread_yield_higher(), since we rely on the RETI instruction at the end
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* of its execution, in the inlined __restore_context() sub-function
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*/
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__attribute__((naked)) void thread_yield_higher(void)
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{
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/*
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* disable IRQ, remembering if they are
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* to be reactivated after context switch
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*/
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unsigned int irqen = disableIRQ();
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__save_context();
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/* have sched_active_thread point to the next thread */
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sched_run();
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__restore_context(irqen);
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UNREACHABLE();
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}
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NORETURN void cpu_switch_context_exit(void)
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{
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sched_active_thread = sched_threads[0];
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sched_run();
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__restore_context(GIE);
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UNREACHABLE();
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}
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/**
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* mspgcc handles main specially - it does not return but falls
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* through to section .fini9.
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* To "fix" this, we put a return in section .fini9 to make main
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* behave like a regular function. This enables a common
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* thread_stack_init behavior. */
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__attribute__((section (".fini9"))) void __main_epilogue(void) { __asm__("ret"); }
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//----------------------------------------------------------------------------
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// Processor specific routine - here for MSP
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//----------------------------------------------------------------------------
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char *thread_stack_init(thread_task_func_t task_func, void *arg, void *stack_start, int stack_size)
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{
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unsigned short stk = (unsigned short)((uintptr_t) stack_start + stack_size);
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/* ensure correct stack alignment (on 16-bit boundary) */
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stk &= 0xfffe;
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unsigned short *stackptr = (unsigned short *)stk;
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/* now make SP point on the first AVAILABLE slot in stack */
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--stackptr;
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*stackptr = (unsigned short) sched_task_exit;
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--stackptr;
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*stackptr = (unsigned short) task_func;
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--stackptr;
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/* initial value for SR */
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*stackptr = GIE;
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--stackptr;
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/* set argument to task_func */
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*stackptr = (unsigned short) arg;
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--stackptr;
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/* Space for registers. */
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for (unsigned int i = 14; i > 4; i--) {
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*stackptr = i;
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--stackptr;
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}
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return (char *) stackptr;
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}
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int inISR(void)
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{
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return __inISR;
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}
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/******************************************************************************/
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/* System reboot */
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int reboot_arch(int mode)
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{
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(void) mode;
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/* force an hardware reboot ("Power-Up Clear"), by writing
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an illegal value to the watchdog control register */
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while (1) {
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WDTCTL = 0x0000;
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}
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return -1;
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}
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