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/jailhouse_para.h> 8 #include <asm/pci_x86.h> 9 10 /* 11 * Discover remaining PCI buses in case there are peer host bridges. 12 * We use the number of last PCI bus provided by the PCI BIOS. 13 */ 14 static void pcibios_fixup_peer_bridges(void) 15 { 16 int n; 17 18 if (pcibios_last_bus <= 0 || pcibios_last_bus > 0xff) 19 return; 20 DBG("PCI: Peer bridge fixup\n"); 21 22 for (n=0; n <= pcibios_last_bus; n++) 23 pcibios_scan_specific_bus(n); 24 } 25 26 int __init pci_legacy_init(void) 27 { 28 if (!raw_pci_ops) 29 return 1; 30 31 pr_info("PCI: Probing PCI hardware\n"); 32 pcibios_scan_root(0); 33 return 0; 34 } 35 36 void pcibios_scan_specific_bus(int busn) 37 { 38 int stride = jailhouse_paravirt() ? 1 : 8; 39 int devfn; 40 u32 l; 41 42 if (pci_find_bus(0, busn)) 43 return; 44 45 for (devfn = 0; devfn < 256; devfn += stride) { 46 if (!raw_pci_read(0, busn, devfn, PCI_VENDOR_ID, 2, &l) && 47 l != 0x0000 && l != 0xffff) { 48 DBG("Found device at %02x:%02x [%04x]\n", busn, devfn, l); 49 pr_info("PCI: Discovered peer bus %02x\n", busn); 50 pcibios_scan_root(busn); 51 return; 52 } 53 } 54 } 55 EXPORT_SYMBOL_GPL(pcibios_scan_specific_bus); 56 57 static int __init pci_subsys_init(void) 58 { 59 /* 60 * The init function returns an non zero value when 61 * pci_legacy_init should be invoked. 62 */ 63 if (x86_init.pci.init()) { 64 if (pci_legacy_init()) { 65 pr_info("PCI: System does not support PCI\n"); 66 return -ENODEV; 67 } 68 } 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); 77