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// SPDX-License-Identifier: GPL-2.0-only
/*
* legacy.c - traditional, old school PCI bus probing
*/
#include <linux/init.h>
#include <linux/export.h>
#include <linux/pci.h>
#include <asm/jailhouse_para.h>
#include <asm/pci_x86.h>
/*
* Discover remaining PCI buses in case there are peer host bridges.
* We use the number of last PCI bus provided by the PCI BIOS.
*/
static void pcibios_fixup_peer_bridges(void)
{
int n;
if (pcibios_last_bus <= 0 || pcibios_last_bus > 0xff)
return;
DBG("PCI: Peer bridge fixup\n");
for (n=0; n <= pcibios_last_bus; n++)
pcibios_scan_specific_bus(n);
}
int __init pci_legacy_init(void)
{
if (!raw_pci_ops)
return 1;
pr_info("PCI: Probing PCI hardware\n");
pcibios_scan_root(0);
return 0;
}
void pcibios_scan_specific_bus(int busn)
{
int stride = jailhouse_paravirt() ? 1 : 8;
int devfn;
u32 l;
if (pci_find_bus(0, busn))
return;
for (devfn = 0; devfn < 256; devfn += stride) {
if (!raw_pci_read(0, busn, devfn, PCI_VENDOR_ID, 2, &l) &&
l != 0x0000 && l != 0xffff) {
DBG("Found device at %02x:%02x [%04x]\n", busn, devfn, l);
pr_info("PCI: Discovered peer bus %02x\n", busn);
pcibios_scan_root(busn);
return;
}
}
}
EXPORT_SYMBOL_GPL(pcibios_scan_specific_bus);
static int __init pci_subsys_init(void)
{
/*
* The init function returns an non zero value when
* pci_legacy_init should be invoked.
*/
if (x86_init.pci.init()) {
if (pci_legacy_init()) {
pr_info("PCI: System does not support PCI\n");
return -ENODEV;
}
}
pcibios_fixup_peer_bridges();
x86_init.pci.init_irq();
pcibios_init();
return 0;
}
subsys_initcall(pci_subsys_init);
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