arch/mips/pci/pci-generic.c

   1 /*
   2  * Copyright (C) 2016 Imagination Technologies
   3  * Author: Paul Burton <paul.burton@mips.com>
   4  *
   5  * pcibios_align_resource taken from arch/arm/kernel/bios32.c.
   6  *
   7  * This program is free software; you can redistribute it and/or modify it
   8  * under the terms of the GNU General Public License as published by the
   9  * Free Software Foundation;  either version 2 of the  License, or (at your
  10  * option) any later version.
  11  */
  12
  13 #include <linux/pci.h>
  14
  15 /*
  16  * We need to avoid collisions with `mirrored' VGA ports
  17  * and other strange ISA hardware, so we always want the
  18  * addresses to be allocated in the 0x000-0x0ff region
  19  * modulo 0x400.
  20  *
  21  * Why? Because some silly external IO cards only decode
  22  * the low 10 bits of the IO address. The 0x00-0xff region
  23  * is reserved for motherboard devices that decode all 16
  24  * bits, so it's ok to allocate at, say, 0x2800-0x28ff,
  25  * but we want to try to avoid allocating at 0x2900-0x2bff
  26  * which might have be mirrored at 0x0100-0x03ff..
  27  */
  28 resource_size_t pcibios_align_resource(void *data, const struct resource *res,
  29                                 resource_size_t size, resource_size_t align)
  30 {
  31         struct pci_dev *dev = data;
  32         resource_size_t start = res->start;
  33         struct pci_host_bridge *host_bridge;
  34
  35         if (res->flags & IORESOURCE_IO && start & 0x300)
  36                 start = (start + 0x3ff) & ~0x3ff;
  37
  38         start = (start + align - 1) & ~(align - 1);
  39
  40         host_bridge = pci_find_host_bridge(dev->bus);
  41
  42         if (host_bridge->align_resource)
  43                 return host_bridge->align_resource(dev, res,
  44                                 start, size, align);
  45
  46         return start;
  47 }
  48
  49 void pcibios_fixup_bus(struct pci_bus *bus)
  50 {
  51         pci_read_bridge_bases(bus);
  52 }