1 | // SPDX-License-Identifier: GPL-2.0-only |
2 | /* |
3 | * legacy.c - traditional, old school PCI bus probing |
4 | */ |
5 | #include <linux/init.h> |
6 | #include <linux/export.h> |
7 | #include <linux/pci.h> |
8 | #include <asm/jailhouse_para.h> |
9 | #include <asm/pci_x86.h> |
10 | |
11 | /* |
12 | * Discover remaining PCI buses in case there are peer host bridges. |
13 | * We use the number of last PCI bus provided by the PCI BIOS. |
14 | */ |
15 | static void pcibios_fixup_peer_bridges(void) |
16 | { |
17 | int n; |
18 | |
19 | if (pcibios_last_bus <= 0 || pcibios_last_bus > 0xff) |
20 | return; |
21 | DBG("PCI: Peer bridge fixup\n" ); |
22 | |
23 | for (n=0; n <= pcibios_last_bus; n++) |
24 | pcibios_scan_specific_bus(busn: n); |
25 | } |
26 | |
27 | int __init pci_legacy_init(void) |
28 | { |
29 | if (!raw_pci_ops) |
30 | return 1; |
31 | |
32 | pr_info("PCI: Probing PCI hardware\n" ); |
33 | pcibios_scan_root(bus: 0); |
34 | return 0; |
35 | } |
36 | |
37 | void pcibios_scan_specific_bus(int busn) |
38 | { |
39 | int stride = jailhouse_paravirt() ? 1 : 8; |
40 | int devfn; |
41 | u32 l; |
42 | |
43 | if (pci_find_bus(domain: 0, busnr: busn)) |
44 | return; |
45 | |
46 | for (devfn = 0; devfn < 256; devfn += stride) { |
47 | if (!raw_pci_read(domain: 0, bus: busn, devfn, PCI_VENDOR_ID, len: 2, val: &l) && |
48 | l != 0x0000 && l != 0xffff) { |
49 | DBG("Found device at %02x:%02x [%04x]\n" , busn, devfn, l); |
50 | pr_info("PCI: Discovered peer bus %02x\n" , busn); |
51 | pcibios_scan_root(bus: busn); |
52 | return; |
53 | } |
54 | } |
55 | } |
56 | EXPORT_SYMBOL_GPL(pcibios_scan_specific_bus); |
57 | |
58 | static int __init pci_subsys_init(void) |
59 | { |
60 | /* |
61 | * The init function returns an non zero value when |
62 | * pci_legacy_init should be invoked. |
63 | */ |
64 | if (x86_init.pci.init()) { |
65 | if (pci_legacy_init()) { |
66 | pr_info("PCI: System does not support PCI\n" ); |
67 | return -ENODEV; |
68 | } |
69 | } |
70 | |
71 | pcibios_fixup_peer_bridges(); |
72 | x86_init.pci.init_irq(); |
73 | pcibios_init(); |
74 | |
75 | return 0; |
76 | } |
77 | subsys_initcall(pci_subsys_init); |
78 | |