resource.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/kernel/resource.c
 *
 * Copyright (C) 1995	Linus Torvalds
 *			David Hinds
 *
 * Kernel io-region resource management
 */

#include <sys/types.h>

#define MACH_INCLUDE
#include <linux/sched.h>
#include <linux/kernel.h>
#include <linux/errno.h>
#include <linux/types.h>
#include <linux/ioport.h>

#define IOTABLE_SIZE 128

typedef struct resource_entry_t
{
  u_long from, num;
  const char *name;
  struct resource_entry_t *next;
} resource_entry_t;

static resource_entry_t iolist = { 0, 0, "", NULL };

static resource_entry_t iotable[IOTABLE_SIZE];

/*
 * This generates the report for /proc/ioports
 */
#ifndef MACH
int
get_ioport_list (char *buf)
{
  resource_entry_t *p;
  int len = 0;
  
  for (p = iolist.next; (p) && (len < 4000); p = p->next)
    len += linux_sprintf (buf+len, "%04lx-%04lx : %s\n",
			  p->from, p->from+p->num-1, p->name);
  if (p)
    len += linux_sprintf (buf+len, "4K limit reached!\n");
  return len;
}
#endif

/*
 * The workhorse function: find where to put a new entry
 */
static resource_entry_t *
find_gap (resource_entry_t *root, u_long from, u_long num)
{
  unsigned long flags;
  resource_entry_t *p;
  
  if (from > from+num-1)
    return NULL;
  save_flags (flags);
  cli ();
  for (p = root; ; p = p->next)
    {
      if ((p != root) && (p->from+p->num-1 >= from))
	{
	  p = NULL;
	  break;
	}
      if ((p->next == NULL) || (p->next->from > from+num-1))
	break;
    }
  restore_flags (flags);
  return p;
}

/*
 * Call this from the device driver to register the ioport region.
 */
void
request_region (unsigned int from, unsigned int num, const char *name)
{
  resource_entry_t *p;
  int i;
  
  for (i = 0; i < IOTABLE_SIZE; i++)
    if (iotable[i].num == 0)
      break;
  if (i == IOTABLE_SIZE)
    printk ("warning: ioport table is full\n");
  else
    {
      p = find_gap (&iolist, from, num);
      if (p == NULL)
	return;
      iotable[i].name = name;
      iotable[i].from = from;
      iotable[i].num = num;
      iotable[i].next = p->next;
      p->next = &iotable[i];
      return;
    }
}

/* 
 * Call this when the device driver is unloaded
 */
void
release_region (unsigned int from, unsigned int num)
{
  resource_entry_t *p, *q;
  
  for (p = &iolist; ; p = q)
    {
      q = p->next;
      if (q == NULL)
	break;
      if ((q->from == from) && (q->num == num))
	{
	  q->num = 0;
	  p->next = q->next;
	  return;
	}
    }
}

/*
 * Call this to check the ioport region before probing
 */
int
check_region (unsigned int from, unsigned int num)
{
  return (find_gap (&iolist, from, num) == NULL) ? -LINUX_EBUSY : 0;
}

/* Called from init/main.c to reserve IO ports. */
void
reserve_setup(char *str, int *ints)
{
  int i;
  
  for (i = 1; i < ints[0]; i += 2)
    request_region (ints[i], ints[i+1], "reserved");
}