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 <asm/pci_x86.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 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         printk("PCI: Probing PCI hardware\n");
  46         pci_root_bus = pcibios_scan_root(0);
  47         if (pci_root_bus)
  48                 pci_bus_add_devices(pci_root_bus);
  49
  50         return 0;
  51 }
  52
  53 int __init pci_subsys_init(void)
  54 {
  55         /*
  56          * The init function returns an non zero value when
  57          * pci_legacy_init should be invoked.
  58          */
  59         if (x86_init.pci.init())
  60                 pci_legacy_init();
  61
  62         pcibios_fixup_peer_bridges();
  63         x86_init.pci.init_irq();
  64         pcibios_init();
  65
  66         return 0;
  67 }
  68 subsys_initcall(pci_subsys_init);