kernel/resource.c

   1 /*
   2  *      linux/kernel/resource.c
   3  *
   4  * Copyright (C) 1995   Linus Torvalds
   5  *                      David Hinds
   6  *
   7  * Kernel io-region resource management
   8  */
   9
  10 #include <linux/sched.h>
  11 #include <linux/errno.h>
  12 #include <linux/ioport.h>
  13 #include <linux/init.h>
  14
  15 #define IOTABLE_SIZE 128
  16
  17 typedef struct resource_entry_t {
  18         u_long from, num;
  19         const char *name;
  20         struct resource_entry_t *next;
  21 } resource_entry_t;
  22
  23 static resource_entry_t iolist = { 0, 0, "", NULL };
  24
  25 static resource_entry_t iotable[IOTABLE_SIZE];
  26
  27 /*
  28  * This generates the report for /proc/ioports
  29  */
  30 int get_ioport_list(char *buf)
  31 {
  32         resource_entry_t *p;
  33         int len = 0;
  34
  35         for (p = iolist.next; (p) && (len < 4000); p = p->next)
  36                 len += sprintf(buf+len, "%04lx-%04lx : %s\n",
  37                            p->from, p->from+p->num-1, p->name);
  38         if (p)
  39                 len += sprintf(buf+len, "4K limit reached!\n");
  40         return len;
  41 }
  42
  43 /*
  44  * The workhorse function: find where to put a new entry
  45  */
  46 static resource_entry_t *find_gap(resource_entry_t *root,
  47                                   u_long from, u_long num)
  48 {
  49         unsigned long flags;
  50         resource_entry_t *p;
  51
  52         if (from > from+num-1)
  53                 return NULL;
  54         save_flags(flags);
  55         cli();
  56         for (p = root; ; p = p->next) {
  57                 if ((p != root) && (p->from+p->num-1 >= from)) {
  58                         p = NULL;
  59                         break;
  60                 }
  61                 if ((p->next == NULL) || (p->next->from > from+num-1))
  62                         break;
  63         }
  64         restore_flags(flags);
  65         return p;
  66 }
  67
  68 /*
  69  * Call this from the device driver to register the ioport region.
  70  */
  71 void request_region(unsigned long from, unsigned long num, const char *name)
  72 {
  73         resource_entry_t *p;
  74         int i;
  75
  76         for (i = 0; i < IOTABLE_SIZE; i++)
  77                 if (iotable[i].num == 0)
  78                         break;
  79         if (i == IOTABLE_SIZE)
  80                 printk("warning: ioport table is full\n");
  81         else {
  82                 p = find_gap(&iolist, from, num);
  83                 if (p == NULL)
  84                         return;
  85                 iotable[i].name = name;
  86                 iotable[i].from = from;
  87                 iotable[i].num = num;
  88                 iotable[i].next = p->next;
  89                 p->next = &iotable[i];
  90                 return;
  91         }
  92 }
  93
  94 /*
  95  * Call this when the device driver is unloaded
  96  */
  97 void release_region(unsigned long from, unsigned long num)
  98 {
  99         resource_entry_t *p, *q;
 100
 101         for (p = &iolist; ; p = q) {
 102                 q = p->next;
 103                 if (q == NULL)
 104                         break;
 105                 if ((q->from == from) && (q->num == num)) {
 106                         q->num = 0;
 107                         p->next = q->next;
 108                         return;
 109                 }
 110         }
 111 }
 112
 113 /*
 114  * Call this to check the ioport region before probing
 115  */
 116 int check_region(unsigned long from, unsigned long num)
 117 {
 118         return (find_gap(&iolist, from, num) == NULL) ? -EBUSY : 0;
 119 }
 120
 121 #ifdef __sparc__   /* Why to carry unused code on other architectures? */
 122 /*
 123  * This is for architectures with MMU-managed ports (sparc).
 124  */
 125 unsigned long occupy_region(unsigned long base, unsigned long end,
 126                             unsigned long num, unsigned int align, const char *name)
 127 {
 128         unsigned long from = 0, till;
 129         unsigned long flags;
 130         int i;
 131         resource_entry_t *p;            /* Scanning ptr */
 132         resource_entry_t *p1;           /* === p->next */
 133         resource_entry_t *s;            /* Found slot */
 134
 135         if (base > end-1)
 136                 return 0;
 137         if (num > end - base)
 138                 return 0;
 139
 140         for (i = 0; i < IOTABLE_SIZE; i++)
 141                 if (iotable[i].num == 0)
 142                         break;
 143         if (i == IOTABLE_SIZE) {
 144                 /* Driver prints a warning typically. */
 145                 return 0;
 146         }
 147
 148         save_flags(flags);
 149         cli();
 150         /* printk("occupy: search in %08lx[%08lx] ", base, end - base); */
 151         s = NULL;
 152         for (p = &iolist; p != NULL; p = p1) {
 153                 p1 = p->next;
 154                 /* Find window in list */
 155                 from = (p->from+p->num + align-1) & ~((unsigned long)align-1);
 156                 till = (p1 == NULL)? (unsigned long) (0 - (unsigned long)align): p1->from;
 157                 /* printk(" %08lx:%08lx", from, till); */
 158                 /* Clip window with base and end */
 159                 if (from < base) from = base;
 160                 if (till > end) till = end;
 161                 /* See if result is large enougth */
 162                 if (from < till && from + num < till) {
 163                         s = p;
 164                         break;
 165                 }
 166         }
 167         /* printk("\r\n"); */
 168         restore_flags(flags);
 169
 170         if (s == NULL)
 171                 return 0;
 172
 173         iotable[i].name = name;
 174         iotable[i].from = from;
 175         iotable[i].num = num;
 176         iotable[i].next = s->next;
 177         s->next = &iotable[i];
 178         return from;
 179 }
 180 #endif
 181
 182 /* Called from init/main.c to reserve IO ports. */
 183 void __init reserve_setup(char *str, int *ints)
 184 {
 185         int i;
 186
 187         for (i = 1; i < ints[0]; i += 2)
 188                 request_region(ints[i], ints[i+1], "reserved");
 189 }