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 } 49