xv6-65oo2/kernel/plic.c

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#include "types.h"
#include "param.h"
#include "memlayout.h"
#include "riscv.h"
#include "defs.h"
//
// the riscv Platform Level Interrupt Controller (PLIC).
//
void
plicinit(void)
{
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// set desired IRQ priorities non-zero (otherwise disabled).
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*(uint32*)(PLIC + UART0_IRQ*4) = 1;
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*(uint32*)(PLIC + VIRTIO0_IRQ*4) = 1;
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}
void
plicinithart(void)
{
int hart = cpuid();
// set uart's enable bit for this hart's S-mode.
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*(uint32*)PLIC_SENABLE(hart)= (1 << UART0_IRQ) | (1 << VIRTIO0_IRQ);
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// set this hart's S-mode priority threshold to 0.
*(uint32*)PLIC_SPRIORITY(hart) = 0;
}
// ask the PLIC what interrupt we should serve.
int
plic_claim(void)
{
int hart = cpuid();
//int irq = *(uint32*)(PLIC + 0x201004);
int irq = *(uint32*)PLIC_SCLAIM(hart);
return irq;
}
// tell the PLIC we've served this IRQ.
void
plic_complete(int irq)
{
int hart = cpuid();
//*(uint32*)(PLIC + 0x201004) = irq;
*(uint32*)PLIC_SCLAIM(hart) = irq;
}