xref: /openbmc/linux/arch/x86/pci/early.c (revision b830f94f)
1 // SPDX-License-Identifier: GPL-2.0
2 #include <linux/kernel.h>
3 #include <linux/pci.h>
4 #include <asm/pci-direct.h>
5 #include <asm/io.h>
6 #include <asm/pci_x86.h>
7 
8 /* Direct PCI access. This is used for PCI accesses in early boot before
9    the PCI subsystem works. */
10 
11 u32 read_pci_config(u8 bus, u8 slot, u8 func, u8 offset)
12 {
13 	u32 v;
14 	outl(0x80000000 | (bus<<16) | (slot<<11) | (func<<8) | offset, 0xcf8);
15 	v = inl(0xcfc);
16 	return v;
17 }
18 
19 u8 read_pci_config_byte(u8 bus, u8 slot, u8 func, u8 offset)
20 {
21 	u8 v;
22 	outl(0x80000000 | (bus<<16) | (slot<<11) | (func<<8) | offset, 0xcf8);
23 	v = inb(0xcfc + (offset&3));
24 	return v;
25 }
26 
27 u16 read_pci_config_16(u8 bus, u8 slot, u8 func, u8 offset)
28 {
29 	u16 v;
30 	outl(0x80000000 | (bus<<16) | (slot<<11) | (func<<8) | offset, 0xcf8);
31 	v = inw(0xcfc + (offset&2));
32 	return v;
33 }
34 
35 void write_pci_config(u8 bus, u8 slot, u8 func, u8 offset,
36 				    u32 val)
37 {
38 	outl(0x80000000 | (bus<<16) | (slot<<11) | (func<<8) | offset, 0xcf8);
39 	outl(val, 0xcfc);
40 }
41 
42 void write_pci_config_byte(u8 bus, u8 slot, u8 func, u8 offset, u8 val)
43 {
44 	outl(0x80000000 | (bus<<16) | (slot<<11) | (func<<8) | offset, 0xcf8);
45 	outb(val, 0xcfc + (offset&3));
46 }
47 
48 void write_pci_config_16(u8 bus, u8 slot, u8 func, u8 offset, u16 val)
49 {
50 	outl(0x80000000 | (bus<<16) | (slot<<11) | (func<<8) | offset, 0xcf8);
51 	outw(val, 0xcfc + (offset&2));
52 }
53 
54 int early_pci_allowed(void)
55 {
56 	return (pci_probe & (PCI_PROBE_CONF1|PCI_PROBE_NOEARLY)) ==
57 			PCI_PROBE_CONF1;
58 }
59 
60