com32/lib/pci/cfgtype.c

   1 #include "pci/pci.h"
   2 #include <com32.h>
   3 #include <string.h>
   4
   5 enum pci_config_type __pci_cfg_type;
   6
   7 static int type1_ok(void)
   8 {
   9     uint32_t oldcf8, newcf8;
  10
  11     /* Test for Configuration Method #1 */
  12
  13     /* Note: XFree86 writes ~0 and expects to read back 0x80fffffc.  Linux
  14        does this less severe test; go with Linux. */
  15
  16     cli();
  17     outb(1, 0xcfb);             /* For old Intel chipsets */
  18     oldcf8 = inl(0xcf8);
  19     outl(0x80000000, 0xcf8);
  20     newcf8 = inl(0xcf8);
  21     outl(oldcf8, 0xcf8);
  22     sti();
  23
  24     return newcf8 == 0x80000000;
  25 }
  26
  27 static int type2_ok(void)
  28 {
  29     uint8_t oldcf8, oldcfa;
  30     uint8_t cf8, cfa;
  31
  32     /* Test for Configuration Method #2 */
  33
  34     /* CM#2 is hard to probe for, but let's do our best... */
  35
  36     cli();
  37     outb(0, 0xcfb);             /* For old Intel chipsets */
  38     oldcf8 = inb(0xcf8);
  39     outb(0, 0xcf8);
  40     oldcfa = inb(0xcfa);
  41     outb(0, 0xcfa);
  42
  43     cf8 = inb(0xcf8);
  44     cfa = inb(0xcfa);
  45
  46     outb(oldcf8, 0xcf8);
  47     outb(oldcfa, 0xcfa);
  48     sti();
  49
  50     return cf8 == 0 && cfa == 0;
  51 }
  52
  53 int pci_set_config_type(enum pci_config_type type)
  54 {
  55     static const com32sys_t ireg = {
  56         .eax.l = 0xb101,
  57         .edi.l = 0,
  58         .eflags.l = EFLAGS_CF,
  59     };
  60     com32sys_t oreg;
  61
  62     if (type == PCI_CFG_AUTO) {
  63         type = PCI_CFG_NONE;
  64
  65         /* Try to detect PCI BIOS */
  66         __intcall(0x1a, &ireg, &oreg);
  67
  68         if (!(oreg.eflags.l & EFLAGS_CF) &&
  69             oreg.eax.b[1] == 0 && oreg.edx.l == 0x20494250) {
  70             /* PCI BIOS present.  Use direct access if we know how to do it. */
  71
  72             if ((oreg.eax.b[0] & 1) && type1_ok())
  73                 type = PCI_CFG_TYPE1;
  74             else if ((oreg.eax.b[0] & 2) && type2_ok())
  75                 type = PCI_CFG_TYPE2;
  76             else
  77                 type = PCI_CFG_BIOS;    /* Use BIOS calls as fallback */
  78
  79         } else if (type1_ok()) {
  80             type = PCI_CFG_TYPE1;
  81         } else if (type2_ok()) {
  82             type = PCI_CFG_TYPE2;
  83         } else {
  84             type = PCI_CFG_NONE;        /* Badness... */
  85         }
  86     }
  87
  88     return (__pci_cfg_type = type);
  89 }