main.c

GNU Mach 微内核源代码, 基于美国卡内基美隆大学的 Mach 研究项目

/*
 * Linux initialization.
 *
 * Copyright (C) 1996 The University of Utah and the Computer Systems
 * Laboratory at the University of Utah (CSL)
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2, or (at your option)
 * any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, 675 Mass Ave, Cambridge, MA 02139, USA.
 *
 *      Author: Shantanu Goel, University of Utah CSL
 */

/*
 *  linux/init/main.c
 *
 *  Copyright (C) 1991, 1992  Linus Torvalds
 */

#include <sys/types.h>

#include <mach/vm_param.h>
#include <mach/vm_prot.h>
#include <mach/machine.h>

#include <vm/vm_page.h>
#include <kern/kalloc.h>

#include <machine/spl.h>
#include <machine/pmap.h>
#include <machine/vm_param.h>

#define MACH_INCLUDE
#include <linux/sched.h>
#include <linux/mm.h>
#include <linux/interrupt.h>
#include <linux/delay.h>
#include <linux/ioport.h>
#include <linux/string.h>

#include <asm/system.h>
#include <asm/io.h>

#include <device-drivers.h>

/*
 * Timing loop count.
 */
unsigned long loops_per_sec = 1;

/*
 * End of physical memory.
 */
unsigned long high_memory;

/*
 * Flag to indicate auto-configuration is in progress.
 */
int linux_auto_config = 1;

/*
 * Hard drive parameters obtained from the BIOS.
 */
struct drive_info_struct
{
  char dummy[32];
} drive_info;

/*
 * Forward declarations.
 */
static void calibrate_delay (void);

extern int hz;
extern vm_offset_t phys_last_addr;

extern void *alloc_contig_mem (unsigned, unsigned, unsigned, vm_page_t *);
extern void free_contig_mem (vm_page_t);
extern void init_IRQ (void);
extern void restore_IRQ (void);
extern void startrtclock (void);
extern void linux_version_init (void);
extern void linux_kmem_init (void);
extern unsigned long pci_init (unsigned long, unsigned long);
extern void linux_net_emulation_init (void);
extern void device_setup (void);
extern void linux_printk (char *,...);
extern int linux_timer_intr (void);
extern spl_t spl0 (void);
extern spl_t splhigh (void);
extern void form_pic_mask (void);
extern int linux_bad_intr (int);
extern int prtnull ();
extern int intnull ();
extern void linux_sched_init (void);


/*
 * Amount of contiguous memory to allocate for initialization.
 */
#define CONTIG_ALLOC (512 * 1024)

/*
 * Initialize Linux drivers.
 */
void
linux_init (void)
{
  int addr;
  unsigned memory_start, memory_end;
  vm_page_t pages;

  /*
   * Initialize memory size.
   */
  high_memory = phys_last_addr;
  init_IRQ ();
  linux_sched_init ();

  /*
   * Set loop count.
   */
  calibrate_delay ();

  /*
   * Initialize drive info.
   */
  addr = *((unsigned *) phystokv (0x104));
  memcpy (&drive_info,
	  (void *) ((addr & 0xffff) + ((addr >> 12) & 0xffff0)), 16);
  addr = *((unsigned *) phystokv (0x118));
  memcpy ((char *) &drive_info + 16,
	  (void *) ((addr & 0xffff) + ((addr >> 12) & 0xffff0)), 16);

  /*
   * Initialize Linux memory allocator.
   */
  linux_kmem_init ();

  /*
   * Allocate contiguous memory below 16 MB.
   */
  memory_start = (unsigned long) alloc_contig_mem (CONTIG_ALLOC,
						   16 * 1024 * 1024,
						   0, &pages);
  if (memory_start == 0)
    panic ("linux_init: alloc_contig_mem failed");
  memory_end = memory_start + CONTIG_ALLOC;

  /*
   * Initialize PCI bus.
   */
  memory_start = pci_init (memory_start, memory_end);

  if (memory_start > memory_end)
    panic ("linux_init: ran out memory");

  /*
   * Free unused memory.
   */
  while (pages && pages->phys_addr < round_page (memory_start))
    pages = (vm_page_t) pages->pageq.next;
  if (pages)
    free_contig_mem (pages);

  /*
   * Initialize devices.
   */
#ifdef CONFIG_INET
  linux_net_emulation_init ();
#endif
  cli ();
  device_setup ();

  restore_IRQ ();
  linux_auto_config = 0;
}

#ifndef NBPW
#define NBPW 32
#endif

/*
 * Allocate contiguous memory with the given constraints.
 * This routine is horribly inefficient but it is presently
 * only used during initialization so it's not that bad.
 */
void *
alloc_contig_mem (unsigned size, unsigned limit,
		  unsigned mask, vm_page_t * pages)
{
  int i, j, bits_len;
  unsigned *bits, len;
  void *m;
  vm_page_t p, page_list, tail, prev;
  vm_offset_t addr, max_addr;

  if (size == 0)
    return (NULL);
  size = round_page (size);
  if ((size >> PAGE_SHIFT) > vm_page_free_count)
    return (NULL);

  /* Allocate bit array.  */
  max_addr = phys_last_addr;
  if (max_addr > limit)
    max_addr = limit;
  bits_len = ((((max_addr >> PAGE_SHIFT) + NBPW - 1) / NBPW)
	      * sizeof (unsigned));
  bits = (unsigned *) kalloc (bits_len);
  if (!bits)
    return (NULL);
  memset (bits, 0, bits_len);

  /*
   * Walk the page free list and set a bit for every usable page.
   */
  simple_lock (&vm_page_queue_free_lock);
  p = vm_page_queue_free;
  while (p)
    {
      if (p->phys_addr < limit)
	(bits[(p->phys_addr >> PAGE_SHIFT) / NBPW]
	 |= 1 << ((p->phys_addr >> PAGE_SHIFT) % NBPW));
      p = (vm_page_t) p->pageq.next;
    }

  /*
   * Scan bit array for contiguous pages.
   */
  len = 0;
  m = NULL;
  for (i = 0; len < size && i < bits_len / sizeof (unsigned); i++)
    for (j = 0; len < size && j < NBPW; j++)
      if (!(bits[i] & (1 << j)))
	{
	  len = 0;
	  m = NULL;
	}
      else
	{
	  if (len == 0)
	    {
	      addr = ((vm_offset_t) (i * NBPW + j)
		      << PAGE_SHIFT);
	      if ((addr & mask) == 0)
		{
		  len += PAGE_SIZE;
		  m = (void *) addr;
		}
	    }
	  else
	    len += PAGE_SIZE;
	}

  if (len != size)
    {
      simple_unlock (&vm_page_queue_free_lock);
      kfree ((vm_offset_t) bits, bits_len);
      return (NULL);
    }

  /*
   * Remove pages from free list
   * and construct list to return to caller.
   */
  page_list = NULL;
  for (len = 0; len < size; len += PAGE_SIZE, addr += PAGE_SIZE)
    {
      prev = NULL;
      for (p = vm_page_queue_free; p; p = (vm_page_t) p->pageq.next)
	{
	  if (p->phys_addr == addr)
	    break;
	  prev = p;
	}
      if (!p)
	panic ("alloc_contig_mem: page not on free list");
      if (prev)
	prev->pageq.next = p->pageq.next;
      else
	vm_page_queue_free = (vm_page_t) p->pageq.next;
      p->free = FALSE;
      p->pageq.next = NULL;
      if (!page_list)
	page_list = tail = p;
      else
	{
	  tail->pageq.next = (queue_entry_t) p;
	  tail = p;
	}
      vm_page_free_count--;
    }

  simple_unlock (&vm_page_queue_free_lock);
  kfree ((vm_offset_t) bits, bits_len);
  if (pages)
    *pages = page_list;
  return (m);
}

/*
 * Free memory allocated by alloc_contig_mem.
 */
void
free_contig_mem (vm_page_t pages)
{
  int i;
  vm_page_t p;

  for (p = pages, i = 0; p->pageq.next; p = (vm_page_t) p->pageq.next, i++)
    p->free = TRUE;
  p->free = TRUE;
  simple_lock (&vm_page_queue_free_lock);
  vm_page_free_count += i + 1;
  p->pageq.next = (queue_entry_t) vm_page_queue_free;
  vm_page_queue_free = pages;
  simple_unlock (&vm_page_queue_free_lock);
}

/* This is the number of bits of precision for the loops_per_second.  Each
 * bit takes on average 1.5/HZ seconds.  This (like the original) is a little
 * better than 1%
 */
#define LPS_PREC 8

static void
calibrate_delay (void)
{
  int ticks;
  int loopbit;
  int lps_precision = LPS_PREC;

  loops_per_sec = (1 << 12);

#ifndef MACH
  printk ("Calibrating delay loop.. ");
#endif
  while (loops_per_sec <<= 1)
    {
      /* wait for "start of" clock tick */
      ticks = jiffies;
      while (ticks == jiffies)
	/* nothing */ ;
      /* Go .. */
      ticks = jiffies;
      __delay (loops_per_sec);
      ticks = jiffies - ticks;
      if (ticks)
	break;
    }

  /* Do a binary approximation to get loops_per_second set to equal one clock
   * (up to lps_precision bits)
   */
  loops_per_sec >>= 1;
  loopbit = loops_per_sec;
  while (lps_precision-- && (loopbit >>= 1))
    {
      loops_per_sec |= loopbit;
      ticks = jiffies;
      while (ticks == jiffies);
      ticks = jiffies;
      __delay (loops_per_sec);
      if (jiffies != ticks)	/* longer than 1 tick */
	loops_per_sec &= ~loopbit;
    }

  /* finally, adjust loops per second in terms of seconds instead of clocks */
  loops_per_sec *= HZ;
  /* Round the value and print it */
#ifndef MACH
  printk ("ok - %lu.%02lu BogoMIPS\n",
	  (loops_per_sec + 2500) / 500000,
	  ((loops_per_sec + 2500) / 5000) % 100);
#endif

#if defined(__SMP__) && defined(__i386__)
  smp_loops_per_tick = loops_per_sec / 400;
#endif
}