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 */
15static 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(n);
25}
26
27int __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(0);
34	return 0;
35}
36
37void 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(0, busn))
44		return;
45
46	for (devfn = 0; devfn < 256; devfn += stride) {
47		if (!raw_pci_read(0, busn, devfn, PCI_VENDOR_ID, 2, &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(busn);
52			return;
53		}
54	}
55}
56EXPORT_SYMBOL_GPL(pcibios_scan_specific_bus);
57
58static 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}
77subsys_initcall(pci_subsys_init);

 
 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 */
14static 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
26int __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
36void 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}
55EXPORT_SYMBOL_GPL(pcibios_scan_specific_bus);
56
57static 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}
76subsys_initcall(pci_subsys_init);