120 lines
3.7 KiB
C
120 lines
3.7 KiB
C
/*
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* SPDX-License-Identifier: BSD-3-Clause
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*
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* Copyright (c) 2020 Felix Kopp <sandtler@sandtler.club>
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*
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* Redistribution and use in source and binary forms, with or without modification, are permitted
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* provided that the following conditions are met:
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*
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* 1. Redistributions of source code must retain the above copyright notice, this list of
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* conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright notice, this list of
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* conditions and the following disclaimer in the documentation and/or other materials
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* provided with the distribution.
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* 3. Neither the name of the copyright holder nor the names of its contributors may be
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* used to endorse or promote products derived from this software without specific prior
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* written permission.
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*
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* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND ANY EXPRESS OR
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* IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND
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* FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR
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* CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
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* DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY,
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* WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY
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* WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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*/
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#include <arch/sched.h>
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#include <arch/at91sam3x8e/hardware.h>
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#include <ardix/string.h>
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#include <ardix/sched.h>
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#include <stdbool.h>
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#include <toolchain.h>
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#ifdef __cplusplus
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extern "C"
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{
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#endif /* __cplusplus */
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/**
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* Set the PENDSV bit in the system control block.
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*/
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static __always_inline void sched_pendsv_req(void)
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{
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REG_SCB_ICSR |= REG_SCB_ICSR_PENDSVSET_BIT;
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}
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void irq_sys_tick(void)
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{
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/*
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* fire a PendSV interrupt and do the actual context switching there
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* because it is faster that way (according to the docs, at least)
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*/
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sched_pendsv_req();
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}
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void sched_init_process_regs(struct reg_snapshot *reg_snap, void (*entry)(void))
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{
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memset(reg_snap, 0, sizeof(*reg_snap));
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reg_snap->hw.lr = (void *)0xFFFFFFF9U;
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reg_snap->hw.pc = entry;
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reg_snap->hw.psr = 0x01000000U;
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}
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/**
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* Set the NVIC priority grouping field in `AIRCR`.
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* Only values from 0..7 are allowed, see the SAM3X documentation.
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*
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* @param prio_group: The new priority grouping value.
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*/
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static inline void sched_nvic_set_prio_group(uint32_t prio_group)
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{
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uint32_t reg_val = REG_SCB_AIRCR;
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reg_val &= ~(REG_SCB_AIRCR_VECTKEY_MASK | REG_SCB_AIRCR_PRIGROUP_MASK);
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reg_val = reg_val
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| REG_SCB_AIRCR_VECTKEY_VAL(REG_SCB_AIRCR_VECTKEY_MAGIC)
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| REG_SCB_AIRCR_PRIGROUP_VAL(prio_group);
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REG_SCB_AIRCR = reg_val;
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}
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int sched_hwtimer_init(unsigned int freq)
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{
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uint32_t ticks = sys_core_clock / freq;
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if (ticks > REG_SYSTICK_LOAD_RELOAD_MASK)
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return 1;
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/* Ensure SysTick and PendSV are preemptive */
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sched_nvic_set_prio_group(0b011);
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REG_SYSTICK_LOAD = (ticks & REG_SYSTICK_LOAD_RELOAD_MASK) - 1;
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REG_SYSTICK_VAL = 0U;
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REG_SYSTICK_CTRL = REG_SYSTICK_CTRL_CLKSOURCE_BIT /* MCK */
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| REG_SYSTICK_CTRL_TICKINT_BIT /* trigger exception */
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| REG_SYSTICK_CTRL_ENABLE_BIT; /* enable SysTick */
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return 0;
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}
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inline void sched_atomic_enter(void)
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{
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REG_SYSTICK_CTRL &= ~REG_SYSTICK_CTRL_ENABLE_BIT;
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}
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inline void sched_atomic_leave(bool resched)
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{
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REG_SYSTICK_CTRL |= REG_SYSTICK_CTRL_ENABLE_BIT;
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}
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void sched_exec_early(void)
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{
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REG_SYSTICK_VAL = 0U; /* Reset timer */
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sched_pendsv_req();
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}
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#ifdef __cplusplus
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} /* extern "C" */
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#endif /* __cplusplus */
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