xv6-65oo2/kernel/plic.c
2022-08-12 10:57:16 -04:00

48 lines
908 B
C

#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)
{
// set desired IRQ priorities non-zero (otherwise disabled).
*(uint32*)(PLIC + UART0_IRQ*4) = 1;
*(uint32*)(PLIC + VIRTIO0_IRQ*4) = 1;
}
void
plicinithart(void)
{
int hart = cpuid();
// set enable bits for this hart's S-mode
// for the uart and virtio disk.
*(uint32*)PLIC_SENABLE(hart) = (1 << UART0_IRQ) | (1 << VIRTIO0_IRQ);
// 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_SCLAIM(hart);
return irq;
}
// tell the PLIC we've served this IRQ.
void
plic_complete(int irq)
{
int hart = cpuid();
*(uint32*)PLIC_SCLAIM(hart) = irq;
}