arch/x86/pci/legacy.c

   1 /*
   2  * legacy.c - traditional, old school PCI bus probing
   3  */
   4 #include <linux/init.h>
   5 #include <linux/pci.h>
   6 #include "pci.h"
   7
   8 /*
   9  * Discover remaining PCI buses in case there are peer host bridges.
  10  * We use the number of last PCI bus provided by the PCI BIOS.
  11  */
  12 static void __devinit pcibios_fixup_peer_bridges(void)
  13 {
  14         int n, devfn;
  15
  16         if (pcibios_last_bus <= 0 || pcibios_last_bus >= 0xff)
  17                 return;
  18         DBG("PCI: Peer bridge fixup\n");
  19
  20         for (n=0; n <= pcibios_last_bus; n++) {
  21                 u32 l;
  22                 if (pci_find_bus(0, n))
  23                         continue;
  24                 for (devfn = 0; devfn < 256; devfn += 8) {
  25                         if (!raw_pci_read(0, n, devfn, PCI_VENDOR_ID, 2, &l) &&
  26                             l != 0x0000 && l != 0xffff) {
  27                                 DBG("Found device at %02x:%02x [%04x]\n", n, devfn, l);
  28                                 printk(KERN_INFO "PCI: Discovered peer bus %02x\n", n);
  29                                 pci_scan_bus_with_sysdata(n);
  30                                 break;
  31                         }
  32                 }
  33         }
  34 }
  35
  36 static int __init pci_legacy_init(void)
  37 {
  38         if (!raw_pci_ops) {
  39                 printk("PCI: System does not support PCI\n");
  40                 return 0;
  41         }
  42
  43         if (pcibios_scanned++)
  44                 return 0;
  45
  46         printk("PCI: Probing PCI hardware\n");
  47         pci_root_bus = pcibios_scan_root(0);
  48         if (pci_root_bus)
  49                 pci_bus_add_devices(pci_root_bus);
  50
  51         pcibios_fixup_peer_bridges();
  52
  53         return 0;
  54 }
  55
  56 subsys_initcall(pci_legacy_init);