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;
  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                 pcibios_scan_specific_bus(n);
  22 }
  23
  24 int __init pci_legacy_init(void)
  25 {
  26         if (!raw_pci_ops) {
  27                 printk("PCI: System does not support PCI\n");
  28                 return 0;
  29         }
  30
  31         printk("PCI: Probing PCI hardware\n");
  32         pci_root_bus = pcibios_scan_root(0);
  33         if (pci_root_bus)
  34                 pci_bus_add_devices(pci_root_bus);
  35
  36         return 0;
  37 }
  38
  39 void __devinit pcibios_scan_specific_bus(int busn)
  40 {
  41         int devfn;
  42         long node;
  43         u32 l;
  44
  45         if (pci_find_bus(0, busn))
  46                 return;
  47
  48         node = get_mp_bus_to_node(busn);
  49         for (devfn = 0; devfn < 256; devfn += 8) {
  50                 if (!raw_pci_read(0, busn, devfn, PCI_VENDOR_ID, 2, &l) &&
  51                     l != 0x0000 && l != 0xffff) {
  52                         DBG("Found device at %02x:%02x [%04x]\n", busn, devfn, l);
  53                         printk(KERN_INFO "PCI: Discovered peer bus %02x\n", busn);
  54                         pci_scan_bus_on_node(busn, &pci_root_ops, node);
  55                         return;
  56                 }
  57         }
  58 }
  59 EXPORT_SYMBOL_GPL(pcibios_scan_specific_bus);
  60
  61 int __init pci_subsys_init(void)
  62 {
  63         /*
  64          * The init function returns an non zero value when
  65          * pci_legacy_init should be invoked.
  66          */
  67         if (x86_init.pci.init())
  68                 pci_legacy_init();
  69
  70         pcibios_fixup_peer_bridges();
  71         x86_init.pci.init_irq();
  72         pcibios_init();
  73
  74         return 0;
  75 }
  76 subsys_initcall(pci_subsys_init);