1 // SPDX-License-Identifier: GPL-2.0-or-later
2 /*
3 * Copyright (C) 2016 Imagination Technologies
4 * Author: Paul Burton <paul.burton@mips.com>
5 *
6 * pcibios_align_resource taken from arch/arm/kernel/bios32.c.
7 */
8
9 #include <linux/pci.h>
10
11 /*
12 * We need to avoid collisions with `mirrored' VGA ports
13 * and other strange ISA hardware, so we always want the
14 * addresses to be allocated in the 0x000-0x0ff region
15 * modulo 0x400.
16 *
17 * Why? Because some silly external IO cards only decode
18 * the low 10 bits of the IO address. The 0x00-0xff region
19 * is reserved for motherboard devices that decode all 16
20 * bits, so it's ok to allocate at, say, 0x2800-0x28ff,
21 * but we want to try to avoid allocating at 0x2900-0x2bff
22 * which might have be mirrored at 0x0100-0x03ff..
23 */
24 resource_size_t pcibios_align_resource(void *data, const struct resource *res,
25 resource_size_t size, resource_size_t align)
26 {
27 struct pci_dev *dev = data;
28 resource_size_t start = res->start;
29 struct pci_host_bridge *host_bridge;
30
31 if (res->flags & IORESOURCE_IO && start & 0x300)
32 start = (start + 0x3ff) & ~0x3ff;
33
34 start = (start + align - 1) & ~(align - 1);
35
36 host_bridge = pci_find_host_bridge(dev->bus);
37
38 if (host_bridge->align_resource)
39 return host_bridge->align_resource(dev, res,
40 start, size, align);
41
42 return start;
43 }
44
45 void pcibios_fixup_bus(struct pci_bus *bus)
46 {
47 pci_read_bridge_bases(bus);
48 }