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 }