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         long node;
  16
  17         if (pcibios_last_bus <= 0 || pcibios_last_bus >= 0xff)
  18                 return;
  19         DBG("PCI: Peer bridge fixup\n");
  20
  21         for (n=0; n <= pcibios_last_bus; n++) {
  22                 u32 l;
  23                 if (pci_find_bus(0, n))
  24                         continue;
  25                 node = get_mp_bus_to_node(n);
  26                 for (devfn = 0; devfn < 256; devfn += 8) {
  27                         if (!raw_pci_read(0, n, devfn, PCI_VENDOR_ID, 2, &l) &&
  28                             l != 0x0000 && l != 0xffff) {
  29                                 DBG("Found device at %02x:%02x [%04x]\n", n, devfn, l);
  30                                 printk(KERN_INFO "PCI: Discovered peer bus %02x\n", n);
  31                                 pci_scan_bus_on_node(n, &pci_root_ops, node);
  32                                 break;
  33                         }
  34                 }
  35         }
  36 }
  37
  38 static int __init pci_legacy_init(void)
  39 {
  40         if (!raw_pci_ops) {
  41                 printk("PCI: System does not support PCI\n");
  42                 return 0;
  43         }
  44
  45         if (pcibios_scanned++)
  46                 return 0;
  47
  48         printk("PCI: Probing PCI hardware\n");
  49         pci_root_bus = pcibios_scan_root(0);
  50         if (pci_root_bus)
  51                 pci_bus_add_devices(pci_root_bus);
  52
  53         pcibios_fixup_peer_bridges();
  54
  55         return 0;
  56 }
  57
  58 subsys_initcall(pci_legacy_init);