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RIOT/cpu/fe310/irq_arch.c
Bas Stottelaar fb61443bbd cpu/*: remove unused assert.h include
2020-10-22 11:13:09 +02:00

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/*
* Copyright (C) 2017, 2019 Ken Rabold, JP Bonn
*
* This file is subject to the terms and conditions of the GNU Lesser
* General Public License v2.1. See the file LICENSE in the top level
* directory for more details.
*/
/**
* @ingroup cpu_fe310
* @{
*
* @file cpu.c
* @brief Implementation of the CPU IRQ management for SiFive FE310
*
* @author Ken Rabold
* @}
*/
#include <stdio.h>
#include <inttypes.h>
#include "macros/xtstr.h"
#include "cpu.h"
#include "context_frame.h"
#include "irq.h"
#include "irq_arch.h"
#include "panic.h"
#include "sched.h"
#include "plic.h"
#include "vendor/encoding.h"
#include "vendor/platform.h"
#include "vendor/plic_driver.h"
/* Default state of mstatus register */
#define MSTATUS_DEFAULT (MSTATUS_MPP | MSTATUS_MPIE)
volatile int fe310_in_isr = 0;
/**
* @brief ISR trap vector
*/
static void trap_entry(void);
/**
* @brief Timer ISR
*/
void timer_isr(void);
void irq_init(void)
{
/* Setup trap handler function */
write_csr(mtvec, &trap_entry);
/* Clear all interrupt enables */
write_csr(mie, 0);
/* Initial PLIC external interrupt controller */
if (IS_ACTIVE(MODULE_PERIPH_PLIC)) {
plic_init();
}
/* Enable SW and external interrupts */
set_csr(mie, MIP_MSIP);
set_csr(mie, MIP_MEIP);
/* Set default state of mstatus */
set_csr(mstatus, MSTATUS_DEFAULT);
}
/**
* @brief Global trap and interrupt handler
*/
void handle_trap(uint32_t mcause)
{
/* Tell RIOT to set sched_context_switch_request instead of
* calling thread_yield(). */
fe310_in_isr = 1;
/* Check for INT or TRAP */
if ((mcause & MCAUSE_INT) == MCAUSE_INT) {
/* Cause is an interrupt - determine type */
switch (mcause & MCAUSE_CAUSE) {
case IRQ_M_SOFT:
/* Handle software interrupt - flag for context switch */
sched_context_switch_request = 1;
CLINT_REG(0) = 0;
break;
#ifdef MODULE_PERIPH_TIMER
case IRQ_M_TIMER:
/* Handle timer interrupt */
timer_isr();
break;
#endif
case IRQ_M_EXT:
/* Handle external interrupt */
if (IS_ACTIVE(MODULE_PERIPH_PLIC)) {
plic_isr_handler();
}
break;
default:
/* Unknown interrupt */
core_panic(PANIC_GENERAL_ERROR, "Unhandled interrupt");
break;
}
}
else {
#ifdef DEVELHELP
printf("Unhandled trap:\n");
printf(" mcause: 0x%"PRIx32"\n", mcause);
printf(" mepc: 0x%"PRIx32"\n", read_csr(mepc));
printf(" mtval: 0x%"PRIx32"\n", read_csr(mtval));
#endif
/* Unknown trap */
core_panic(PANIC_GENERAL_ERROR, "Unhandled trap");
}
/* ISR done - no more changes to thread states */
fe310_in_isr = 0;
}
/* Marking this as interrupt to ensure an mret at the end, provided by the
* compiler. Aligned to 4-byte boundary as per RISC-V spec */
static void __attribute((aligned(4))) __attribute__((interrupt)) trap_entry(void) {
__asm__ volatile (
"addi sp, sp, -"XTSTR(CONTEXT_FRAME_SIZE)" \n"
/* Save caller-saved registers */
"sw ra, "XTSTR(ra_OFFSET)"(sp) \n"
"sw t0, "XTSTR(t0_OFFSET)"(sp) \n"
"sw t1, "XTSTR(t1_OFFSET)"(sp) \n"
"sw t2, "XTSTR(t2_OFFSET)"(sp) \n"
"sw t3, "XTSTR(t3_OFFSET)"(sp) \n"
"sw t4, "XTSTR(t4_OFFSET)"(sp) \n"
"sw t5, "XTSTR(t5_OFFSET)"(sp) \n"
"sw t6, "XTSTR(t6_OFFSET)"(sp) \n"
"sw a0, "XTSTR(a0_OFFSET)"(sp) \n"
"sw a1, "XTSTR(a1_OFFSET)"(sp) \n"
"sw a2, "XTSTR(a2_OFFSET)"(sp) \n"
"sw a3, "XTSTR(a3_OFFSET)"(sp) \n"
"sw a4, "XTSTR(a4_OFFSET)"(sp) \n"
"sw a5, "XTSTR(a5_OFFSET)"(sp) \n"
"sw a6, "XTSTR(a6_OFFSET)"(sp) \n"
"sw a7, "XTSTR(a7_OFFSET)"(sp) \n"
/* Save s0 and s1 extra for the active thread and the stack ptr */
"sw s0, "XTSTR(s0_OFFSET)"(sp) \n"
"sw s1, "XTSTR(s1_OFFSET)"(sp) \n"
/* Save the user stack ptr */
"mv s0, sp \n"
/* Load exception stack ptr */
"la sp, _sp \n"
/* Get the interrupt cause */
"csrr a0, mcause \n"
/* Call trap handler, a0 contains mcause before, and the return value after
* the call */
"call handle_trap \n"
/* Load the sched_context_switch_request */
"lw a0, sched_context_switch_request \n"
/* And skip the context switch if not requested */
"beqz a0, no_sched \n"
/* Get the previous active thread (could be NULL) */
"lw s1, sched_active_thread \n"
/* Run the scheduler */
"call sched_run \n"
"no_sched: \n"
/* Restore the thread stack pointer and check if a new thread must be
* scheduled */
"mv sp, s0 \n"
/* No context switch required, shortcut to restore. a0 contains the return
* value of sched_run, or the sched_context_switch_request if the sched_run
* was skipped */
"beqz a0, no_switch \n"
/* Skips the rest of the save if no active thread */
"beqz s1, null_thread \n"
/* Store s2-s11 */
"sw s2, "XTSTR(s2_OFFSET)"(sp) \n"
"sw s3, "XTSTR(s3_OFFSET)"(sp) \n"
"sw s4, "XTSTR(s4_OFFSET)"(sp) \n"
"sw s5, "XTSTR(s5_OFFSET)"(sp) \n"
"sw s6, "XTSTR(s6_OFFSET)"(sp) \n"
"sw s7, "XTSTR(s7_OFFSET)"(sp) \n"
"sw s8, "XTSTR(s8_OFFSET)"(sp) \n"
"sw s9, "XTSTR(s9_OFFSET)"(sp) \n"
"sw s10, "XTSTR(s10_OFFSET)"(sp) \n"
"sw s11, "XTSTR(s11_OFFSET)"(sp) \n"
/* Grab mepc to save it to the stack */
"csrr s2, mepc \n"
/* Save return PC in stack frame */
"sw s2, "XTSTR(pc_OFFSET)"(sp) \n"
/* Save stack pointer of current thread */
"sw sp, "XTSTR(SP_OFFSET_IN_THREAD)"(s1) \n"
/* Context saving done, from here on the new thread is scheduled */
"null_thread: \n"
/* Get the new active thread (guaranteed to be non NULL) */
"lw s1, sched_active_thread \n"
/* Load the thread SP of scheduled thread */
"lw sp, "XTSTR(SP_OFFSET_IN_THREAD)"(s1) \n"
/* Set return PC to mepc */
"lw a1, "XTSTR(pc_OFFSET)"(sp) \n"
"csrw mepc, a1 \n"
/* restore s2-s11 */
"lw s2, "XTSTR(s2_OFFSET)"(sp) \n"
"lw s3, "XTSTR(s3_OFFSET)"(sp) \n"
"lw s4, "XTSTR(s4_OFFSET)"(sp) \n"
"lw s5, "XTSTR(s5_OFFSET)"(sp) \n"
"lw s6, "XTSTR(s6_OFFSET)"(sp) \n"
"lw s7, "XTSTR(s7_OFFSET)"(sp) \n"
"lw s8, "XTSTR(s8_OFFSET)"(sp) \n"
"lw s9, "XTSTR(s9_OFFSET)"(sp) \n"
"lw s10, "XTSTR(s10_OFFSET)"(sp) \n"
"lw s11, "XTSTR(s11_OFFSET)"(sp) \n"
"no_switch: \n"
/* restore the caller-saved registers */
"lw ra, "XTSTR(ra_OFFSET)"(sp) \n"
"lw t0, "XTSTR(t0_OFFSET)"(sp) \n"
"lw t1, "XTSTR(t1_OFFSET)"(sp) \n"
"lw t2, "XTSTR(t2_OFFSET)"(sp) \n"
"lw t3, "XTSTR(t3_OFFSET)"(sp) \n"
"lw t4, "XTSTR(t4_OFFSET)"(sp) \n"
"lw t5, "XTSTR(t5_OFFSET)"(sp) \n"
"lw t6, "XTSTR(t6_OFFSET)"(sp) \n"
"lw a0, "XTSTR(a0_OFFSET)"(sp) \n"
"lw a1, "XTSTR(a1_OFFSET)"(sp) \n"
"lw a2, "XTSTR(a2_OFFSET)"(sp) \n"
"lw a3, "XTSTR(a3_OFFSET)"(sp) \n"
"lw a4, "XTSTR(a4_OFFSET)"(sp) \n"
"lw a5, "XTSTR(a5_OFFSET)"(sp) \n"
"lw a6, "XTSTR(a6_OFFSET)"(sp) \n"
"lw a7, "XTSTR(a7_OFFSET)"(sp) \n"
"lw s0, "XTSTR(s0_OFFSET)"(sp) \n"
"lw s1, "XTSTR(s1_OFFSET)"(sp) \n"
"addi sp, sp, "XTSTR(CONTEXT_FRAME_SIZE)" \n"
:
:
:
);
}
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