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