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 */
pcibios_fixup_peer_bridges(void)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
pci_legacy_init(void)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
pcibios_scan_specific_bus(int busn)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
pci_subsys_init(void)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