1 /* 2 * legacy.c - traditional, old school PCI bus probing 3 */ 4 #include <linux/init.h> 5 #include <linux/export.h> 6 #include <linux/pci.h> 7 #include <asm/pci_x86.h> 8 9 /* 10 * Discover remaining PCI buses in case there are peer host bridges. 11 * We use the number of last PCI bus provided by the PCI BIOS. 12 */ 13 static void pcibios_fixup_peer_bridges(void) 14 { 15 int n; 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 pcibios_scan_specific_bus(n); 23 } 24 25 int __init pci_legacy_init(void) 26 { 27 if (!raw_pci_ops) 28 return 1; 29 30 pr_info("PCI: Probing PCI hardware\n"); 31 pcibios_scan_root(0); 32 return 0; 33 } 34 35 void pcibios_scan_specific_bus(int busn) 36 { 37 int devfn; 38 u32 l; 39 40 if (pci_find_bus(0, busn)) 41 return; 42 43 for (devfn = 0; devfn < 256; devfn += 8) { 44 if (!raw_pci_read(0, busn, devfn, PCI_VENDOR_ID, 2, &l) && 45 l != 0x0000 && l != 0xffff) { 46 DBG("Found device at %02x:%02x [%04x]\n", busn, devfn, l); 47 pr_info("PCI: Discovered peer bus %02x\n", busn); 48 pcibios_scan_root(busn); 49 return; 50 } 51 } 52 } 53 EXPORT_SYMBOL_GPL(pcibios_scan_specific_bus); 54 55 static int __init pci_subsys_init(void) 56 { 57 /* 58 * The init function returns an non zero value when 59 * pci_legacy_init should be invoked. 60 */ 61 if (x86_init.pci.init()) { 62 if (pci_legacy_init()) { 63 pr_info("PCI: System does not support PCI\n"); 64 return -ENODEV; 65 } 66 } 67 68 pcibios_fixup_peer_bridges(); 69 x86_init.pci.init_irq(); 70 pcibios_init(); 71 72 return 0; 73 } 74 subsys_initcall(pci_subsys_init); 75