xref: /openbmc/linux/arch/x86/pci/legacy.c (revision e23feb16)
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 		printk("PCI: System does not support PCI\n");
29 		return 0;
30 	}
31 
32 	printk("PCI: Probing PCI hardware\n");
33 	pcibios_scan_root(0);
34 	return 0;
35 }
36 
37 void pcibios_scan_specific_bus(int busn)
38 {
39 	int devfn;
40 	long node;
41 	u32 l;
42 
43 	if (pci_find_bus(0, busn))
44 		return;
45 
46 	node = get_mp_bus_to_node(busn);
47 	for (devfn = 0; devfn < 256; devfn += 8) {
48 		if (!raw_pci_read(0, busn, devfn, PCI_VENDOR_ID, 2, &l) &&
49 		    l != 0x0000 && l != 0xffff) {
50 			DBG("Found device at %02x:%02x [%04x]\n", busn, devfn, l);
51 			printk(KERN_INFO "PCI: Discovered peer bus %02x\n", busn);
52 			pci_scan_bus_on_node(busn, &pci_root_ops, node);
53 			return;
54 		}
55 	}
56 }
57 EXPORT_SYMBOL_GPL(pcibios_scan_specific_bus);
58 
59 int __init pci_subsys_init(void)
60 {
61 	/*
62 	 * The init function returns an non zero value when
63 	 * pci_legacy_init should be invoked.
64 	 */
65 	if (x86_init.pci.init())
66 		pci_legacy_init();
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