1 // SPDX-License-Identifier: GPL-2.0
2 #include <linux/kernel.h>
4 #include <asm/pci-direct.h>
6 #include <asm/pci_x86.h>
8 /* Direct PCI access. This is used for PCI accesses in early boot before
9 the PCI subsystem works. */
11 u32 read_pci_config(u8 bus, u8 slot, u8 func, u8 offset)
14 outl(0x80000000 | (bus<<16) | (slot<<11) | (func<<8) | offset, 0xcf8);
19 u8 read_pci_config_byte(u8 bus, u8 slot, u8 func, u8 offset)
22 outl(0x80000000 | (bus<<16) | (slot<<11) | (func<<8) | offset, 0xcf8);
23 v = inb(0xcfc + (offset&3));
27 u16 read_pci_config_16(u8 bus, u8 slot, u8 func, u8 offset)
30 outl(0x80000000 | (bus<<16) | (slot<<11) | (func<<8) | offset, 0xcf8);
31 v = inw(0xcfc + (offset&2));
35 void write_pci_config(u8 bus, u8 slot, u8 func, u8 offset,
38 outl(0x80000000 | (bus<<16) | (slot<<11) | (func<<8) | offset, 0xcf8);
42 void write_pci_config_byte(u8 bus, u8 slot, u8 func, u8 offset, u8 val)
44 outl(0x80000000 | (bus<<16) | (slot<<11) | (func<<8) | offset, 0xcf8);
45 outb(val, 0xcfc + (offset&3));
48 void write_pci_config_16(u8 bus, u8 slot, u8 func, u8 offset, u16 val)
50 outl(0x80000000 | (bus<<16) | (slot<<11) | (func<<8) | offset, 0xcf8);
51 outw(val, 0xcfc + (offset&2));
54 int early_pci_allowed(void)
56 return (pci_probe & (PCI_PROBE_CONF1|PCI_PROBE_NOEARLY)) ==