Software of the Month Club 2000 October/Software of the Month - Ultimate Collection Shareware 277.iso/pc/PROGRAMS/UTILITY/WINLINUX/DATA1.CAB/programs_-_kernel_source/KERNEL/RESOURCE.C

C/C++ Source or Header | 1999-09-17 | 4.0 KB | 190 lines

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

#include <linux/sched.h>
#include <linux/errno.h>
#include <linux/ioport.h>
#include <linux/init.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
 */
int get_ioport_list(char *buf)
{
    resource_entry_t *p;
    int len = 0;

    for (p = iolist.next; (p) && (len < 4000); p = p->next)
        len += sprintf(buf+len, "%04lx-%04lx : %s\n",
               p->from, p->from+p->num-1, p->name);
    if (p)
        len += sprintf(buf+len, "4K limit reached!\n");
    return len;
}

/*
 * 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 long from, unsigned long 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 long from, unsigned long 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 long from, unsigned long num)
{
    return (find_gap(&iolist, from, num) == NULL) ? -EBUSY : 0;
}

#ifdef __sparc__   /* Why to carry unused code on other architectures? */
/*
 * This is for architectures with MMU-managed ports (sparc).
 */
unsigned long occupy_region(unsigned long base, unsigned long end,
                unsigned long num, unsigned int align, const char *name)
{
    unsigned long from = 0, till;
    unsigned long flags;
    int i;
    resource_entry_t *p;        /* Scanning ptr */
    resource_entry_t *p1;        /* === p->next */
    resource_entry_t *s;        /* Found slot */

    if (base > end-1)
        return 0;
    if (num > end - base)
        return 0;

    for (i = 0; i < IOTABLE_SIZE; i++)
        if (iotable[i].num == 0)
            break;
    if (i == IOTABLE_SIZE) {
        /* Driver prints a warning typically. */
        return 0;
    }

    save_flags(flags);
    cli();
    /* printk("occupy: search in %08lx[%08lx] ", base, end - base); */
    s = NULL;
    for (p = &iolist; p != NULL; p = p1) {
        p1 = p->next;
        /* Find window in list */
        from = (p->from+p->num + align-1) & ~((unsigned long)align-1);
        till = (p1 == NULL)? (unsigned long) (0 - (unsigned long)align): p1->from;
        /* printk(" %08lx:%08lx", from, till); */
        /* Clip window with base and end */
        if (from < base) from = base;
        if (till > end) till = end;
        /* See if result is large enougth */
        if (from < till && from + num < till) {
            s = p;
            break;
        }
    }
    /* printk("\r\n"); */
    restore_flags(flags);

    if (s == NULL)
        return 0;

    iotable[i].name = name;
    iotable[i].from = from;
    iotable[i].num = num;
    iotable[i].next = s->next;
    s->next = &iotable[i];
    return from;
}
#endif

/* Called from init/main.c to reserve IO ports. */
void __init reserve_setup(char *str, int *ints)
{
    int i;

    for (i = 1; i < ints[0]; i += 2)
        request_region(ints[i], ints[i+1], "reserved");
}