ardix/arch/at91sam3x8e/sched.c

121 lines
3 KiB
C

/* See the end of this file for copyright, license, and warranty information. */
#include <arch-generic/sched.h>
#include <arch/hardware.h>
#include <arch/interrupt.h>
#include <ardix/atomic.h>
#include <ardix/malloc.h>
#include <ardix/sched.h>
#include <errno.h>
#include <string.h>
volatile unsigned long int tick = 0;
unsigned int systick_reload;
unsigned int tick_freq;
void handle_sys_tick(void)
{
tick++;
/*
* fire a PendSV exception and do the actual context switching there
* because the docs say you're supposed to do it that way
*/
if (!is_atomic())
arch_irq_invoke(IRQNO_PEND_SV);
}
/**
* Set the NVIC priority grouping field in `AIRCR`.
* Only values from 0..7 are allowed, see the SAM3X documentation.
*
* @param prio_group: The new priority grouping value.
*/
static inline void sched_nvic_set_prio_group(uint32_t prio_group)
{
uint32_t reg_val = REG_SCB_AIRCR;
reg_val &= ~(REG_SCB_AIRCR_VECTKEY_MASK | REG_SCB_AIRCR_PRIGROUP_MASK);
reg_val = reg_val
| REG_SCB_AIRCR_VECTKEY_VAL(REG_SCB_AIRCR_VECTKEY_MAGIC)
| REG_SCB_AIRCR_PRIGROUP_VAL(prio_group);
REG_SCB_AIRCR = reg_val;
}
int arch_sched_hwtimer_init(unsigned int freq)
{
tick_freq = freq;
systick_reload = sys_core_clock / freq;
if (systick_reload > REG_SYSTICK_LOAD_RELOAD_MASK)
return 1;
/* Ensure SysTick and PendSV are preemptive */
sched_nvic_set_prio_group(0b011);
REG_SYSTICK_LOAD = (systick_reload & REG_SYSTICK_LOAD_RELOAD_MASK) - 1;
REG_SYSTICK_VAL = 0U;
REG_SYSTICK_CTRL = REG_SYSTICK_CTRL_CLKSOURCE_BIT /* MCK */
| REG_SYSTICK_CTRL_TICKINT_BIT /* trigger exception */
| REG_SYSTICK_CTRL_ENABLE_BIT; /* enable SysTick */
return 0;
}
void arch_task_init(struct task *task, void (*entry)(void))
{
struct reg_snapshot *regs = task->stack_bottom - sizeof(*regs);
task->sp = regs;
memset(regs, 0, sizeof(*regs));
regs->hw.pc = entry;
regs->hw.psr = 0x01000000;
regs->sw.lr = (void *)0xfffffff9;
}
void yield(enum task_state state)
{
current->state = state;
arch_irq_invoke(IRQNO_PEND_SV);
}
__naked __noreturn static void idle_task_entry(void)
{
while (1);
}
int arch_idle_task_init(struct task *task)
{
void *stack = malloc(CONFIG_STACK_SIZE);
if (stack == NULL)
return -ENOMEM;
task->stack_bottom = stack + CONFIG_STACK_SIZE - 4;
task->sp = task->stack_bottom - sizeof(struct reg_snapshot);
arch_task_init(task, idle_task_entry);
task->sleep = 0;
task->last_tick = 0;
task->state = TASK_READY;
task->pid = -1;
return 0;
}
unsigned long int ms_to_ticks(unsigned long int ms)
{
return ( ms * (unsigned long int)tick_freq ) / 1000lu /* 1 s = 1000 ms */;
}
/*
* This file is part of Ardix.
* Copyright (c) 2020, 2021 Felix Kopp <owo@fef.moe>.
*
* Ardix is non-violent software: you may only use, redistribute,
* and/or modify it under the terms of the CNPLv6+ as found in
* the LICENSE file in the source code root directory or at
* <https://git.pixie.town/thufie/CNPL>.
*
* Ardix comes with ABSOLUTELY NO WARRANTY, to the extent
* permitted by applicable law. See the CNPLv6+ for details.
*/