xv6/lapic.c

#include "types.h"
#include "mp.h"
#include "defs.h"
#include "param.h"
#include "x86.h"
#include "traps.h"
#include "mmu.h"
#include "proc.h"


/* 
 * Credit: Plan 9 sources, Intel MP spec, and Cliff Frey
 */

enum {					/* Local APIC registers */
  LAPIC_ID  = 0x0020,	/* ID */
  LAPIC_VER = 0x0030,	/* Version */
  LAPIC_TPR = 0x0080,	/* Task Priority */
  LAPIC_APR = 0x0090,	/* Arbitration Priority */
  LAPIC_PPR = 0x00A0,	/* Processor Priority */
  LAPIC_EOI = 0x00B0,	/* EOI */
  LAPIC_LDR = 0x00D0,	/* Logical Destination */
  LAPIC_DFR = 0x00E0,	/* Destination Format */
  LAPIC_SVR = 0x00F0,	/* Spurious Interrupt Vector */
  LAPIC_ISR = 0x0100,	/* Interrupt Status (8 registers) */
  LAPIC_TMR = 0x0180,	/* Trigger Mode (8 registers) */
  LAPIC_IRR = 0x0200,	/* Interrupt Request (8 registers) */
  LAPIC_ESR = 0x0280,	/* Error Status */
  LAPIC_ICRLO = 0x0300,	/* Interrupt Command */
  LAPIC_ICRHI = 0x0310,	/* Interrupt Command [63:32] */
  LAPIC_TIMER = 0x0320,	/* Local Vector Table 0 (TIMER) */
  LAPIC_PCINT = 0x0340,	/* Performance Counter LVT */
  LAPIC_LINT0 = 0x0350,	/* Local Vector Table 1 (LINT0) */
  LAPIC_LINT1 = 0x0360,	/* Local Vector Table 2 (LINT1) */
  LAPIC_ERROR = 0x0370,	/* Local Vector Table 3 (ERROR) */
  LAPIC_TICR = 0x0380,	/* Timer Initial Count */
  LAPIC_TCCR = 0x0390,	/* Timer Current Count */
  LAPIC_TDCR = 0x03E0,	/* Timer Divide Configuration */
};

enum {					/* LAPIC_SVR */
  LAPIC_ENABLE	= 0x00000100,	/* Unit Enable */
  LAPIC_FOCUS	= 0x00000200,	/* Focus Processor Checking Disable */
};

enum {					/* LAPIC_ICRLO */
					/* [14] IPI Trigger Mode Level (RW) */
  LAPIC_DEASSERT = 0x00000000,	/* Deassert level-sensitive interrupt */
  LAPIC_ASSERT	= 0x00004000,	/* Assert level-sensitive interrupt */

  /* [17:16] Remote Read Status */
  LAPIC_INVALID	= 0x00000000,	/* Invalid */
  LAPIC_WAIT	= 0x00010000,	/* In-Progress */
  LAPIC_VALID	= 0x00020000,	/* Valid */

  /* [19:18] Destination Shorthand */
  LAPIC_FIELD	= 0x00000000,	/* No shorthand */
  LAPIC_SELF	= 0x00040000,	/* Self is single destination */
  LAPIC_ALLINC	= 0x00080000,	/* All including self */
  LAPIC_ALLEXC	= 0x000C0000,	/* All Excluding self */
};

enum {					/* LAPIC_ESR */
  LAPIC_SENDCS	= 0x00000001,	/* Send CS Error */
  LAPIC_RCVCS	= 0x00000002,	/* Receive CS Error */
  LAPIC_SENDACCEPT = 0x00000004,	/* Send Accept Error */
  LAPIC_RCVACCEPT = 0x00000008,	/* Receive Accept Error */
  LAPIC_SENDVECTOR = 0x00000020,	/* Send Illegal Vector */
  LAPIC_RCVVECTOR = 0x00000040,	/* Receive Illegal Vector */
  LAPIC_REGISTER = 0x00000080,	/* Illegal Register Address */
};

enum {					/* LAPIC_TIMER */
					/* [17] Timer Mode (RW) */
  LAPIC_ONESHOT	= 0x00000000,	/* One-shot */
  LAPIC_PERIODIC = 0x00020000,	/* Periodic */

  /* [19:18] Timer Base (RW) */
  LAPIC_CLKIN	= 0x00000000,	/* use CLKIN as input */
  LAPIC_TMBASE	= 0x00040000,	/* use TMBASE */
  LAPIC_DIVIDER	= 0x00080000,	/* use output of the divider */
};

enum {					/* LAPIC_TDCR */
  LAPIC_X2 = 0x00000000,	/* divide by 2 */
  LAPIC_X4 = 0x00000001,	/* divide by 4 */
  LAPIC_X8 = 0x00000002,	/* divide by 8 */
  LAPIC_X16 = 0x00000003,	/* divide by 16 */
  LAPIC_X32 = 0x00000008,	/* divide by 32 */
  LAPIC_X64 = 0x00000009,	/* divide by 64 */
  LAPIC_X128 = 0x0000000A,	/* divide by 128 */
  LAPIC_X1 = 0x0000000B,	/* divide by 1 */
};

uint *lapicaddr;

static int
lapic_read(int r)
{
  return *(lapicaddr+(r/sizeof(*lapicaddr)));
}

static void
lapic_write(int r, int data)
{
  *(lapicaddr+(r/sizeof(*lapicaddr))) = data;
}


void
lapic_timerinit(void)
{
  cprintf("%d: init timer\n", cpu());
  lapic_write(LAPIC_TDCR, LAPIC_X1);
  lapic_write(LAPIC_TIMER, LAPIC_CLKIN | LAPIC_PERIODIC | (IRQ_OFFSET + IRQ_TIMER));
  lapic_write(LAPIC_TCCR, 10000000);
  lapic_write(LAPIC_TICR, 10000000);
}

void
lapic_timerintr(void)
{
  cprintf("%d: timer interrupt!\n", cpu());
  lapic_write (LAPIC_EOI, 0);
}

void
lapic_init(int c)
{
  uint r, lvt;

  cprintf("lapic_init %d\n", c);

  lapic_write(LAPIC_DFR, 0xFFFFFFFF); // set destination format register
  r = (lapic_read(LAPIC_ID)>>24) & 0xFF; // read APIC ID
  lapic_write(LAPIC_LDR, (1<<r)<<24);  // set logical destination register to r
  lapic_write(LAPIC_TPR, 0xFF);  // no interrupts for now
  lapic_write(LAPIC_SVR, LAPIC_ENABLE|(IRQ_OFFSET+IRQ_SPURIOUS));  // enable APIC

  // in virtual wire mode, set up the LINT0 and LINT1 as follows:
  lapic_write(LAPIC_LINT0, APIC_IMASK | APIC_EXTINT);
  lapic_write(LAPIC_LINT1, APIC_IMASK | APIC_NMI);

  lapic_write(LAPIC_EOI, 0); // acknowledge any outstanding interrupts.

  lvt = (lapic_read(LAPIC_VER)>>16) & 0xFF;
  if(lvt >= 4)
    lapic_write(LAPIC_PCINT, APIC_IMASK);
  lapic_write(LAPIC_ERROR, IRQ_OFFSET+IRQ_ERROR);
  lapic_write(LAPIC_ESR, 0);
  lapic_read(LAPIC_ESR);

  /*
   * Issue an INIT Level De-Assert to synchronise arbitration ID's.
   */
  lapic_write(LAPIC_ICRHI, 0);
  lapic_write(LAPIC_ICRLO, LAPIC_ALLINC|APIC_LEVEL|LAPIC_DEASSERT|APIC_INIT);
  while(lapic_read(LAPIC_ICRLO) & APIC_DELIVS)
    ;

  cprintf("Done init of an apic\n");
}

void
lapic_enableintr(void) 
{
  lapic_write(LAPIC_TPR, 0);
}

void
lapic_disableintr(void) 
{
  lapic_write(LAPIC_TPR, 0xFF);
}

void
lapic_eoi(void)
{
  lapic_write (LAPIC_EOI, 0);
}

int
cpu(void)
{
  return (lapic_read(LAPIC_ID)>>24) & 0xFF;
}

void
lapic_startap(uchar apicid, int v)
{
  int crhi, i;
  volatile int j = 0;

  crhi = apicid<<24;
  lapic_write(LAPIC_ICRHI, crhi);
  lapic_write(LAPIC_ICRLO, LAPIC_FIELD|APIC_LEVEL|LAPIC_ASSERT|APIC_INIT);

  while (j++ < 10000) {;}
  lapic_write(LAPIC_ICRLO, LAPIC_FIELD|APIC_LEVEL|LAPIC_DEASSERT|APIC_INIT);

  while (j++ < 1000000) {;}

  // in p9 code, this was i < 2, which is what the spec says on page B-3
  for(i = 0; i < 1; i++){
    lapic_write(LAPIC_ICRHI, crhi);
    lapic_write(LAPIC_ICRLO, LAPIC_FIELD|APIC_EDGE|APIC_STARTUP|(v/PGSIZE));
    while (j++ < 100000) {;}
  }
}