arch/m68k/kernel/pcibios.c

   1 // SPDX-License-Identifier: GPL-2.0-or-later
   2 /*
   3  * pci.c -- basic PCI support code
   4  *
   5  * (C) Copyright 2011, Greg Ungerer <gerg@uclinux.org>
   6  */
   7
   8 #include <linux/kernel.h>
   9 #include <linux/types.h>
  10 #include <linux/mm.h>
  11 #include <linux/init.h>
  12 #include <linux/pci.h>
  13
  14 /*
  15  * From arch/i386/kernel/pci-i386.c:
  16  *
  17  * We need to avoid collisions with `mirrored' VGA ports
  18  * and other strange ISA hardware, so we always want the
  19  * addresses to be allocated in the 0x000-0x0ff region
  20  * modulo 0x400.
  21  *
  22  * Why? Because some silly external IO cards only decode
  23  * the low 10 bits of the IO address. The 0x00-0xff region
  24  * is reserved for motherboard devices that decode all 16
  25  * bits, so it's ok to allocate at, say, 0x2800-0x28ff,
  26  * but we want to try to avoid allocating at 0x2900-0x2bff
  27  * which might be mirrored at 0x0100-0x03ff..
  28  */
  29 resource_size_t pcibios_align_resource(void *data, const struct resource *res,
  30         resource_size_t size, resource_size_t align)
  31 {
  32         resource_size_t start = res->start;
  33
  34         if ((res->flags & IORESOURCE_IO) && (start & 0x300))
  35                 start = (start + 0x3ff) & ~0x3ff;
  36
  37         start = (start + align - 1) & ~(align - 1);
  38
  39         return start;
  40 }
  41
  42 /*
  43  * This is taken from the ARM code for this.
  44  */
  45 int pcibios_enable_device(struct pci_dev *dev, int mask)
  46 {
  47         struct resource *r;
  48         u16 cmd, newcmd;
  49         int idx;
  50
  51         pci_read_config_word(dev, PCI_COMMAND, &cmd);
  52         newcmd = cmd;
  53
  54         for (idx = 0; idx < 6; idx++) {
  55                 /* Only set up the requested stuff */
  56                 if (!(mask & (1 << idx)))
  57                         continue;
  58
  59                 r = dev->resource + idx;
  60                 if (!r->start && r->end) {
  61                         pr_err("PCI: Device %s not available because of resource collisions\n",
  62                                 pci_name(dev));
  63                         return -EINVAL;
  64                 }
  65                 if (r->flags & IORESOURCE_IO)
  66                         newcmd |= PCI_COMMAND_IO;
  67                 if (r->flags & IORESOURCE_MEM)
  68                         newcmd |= PCI_COMMAND_MEMORY;
  69         }
  70
  71         /*
  72          * Bridges (eg, cardbus bridges) need to be fully enabled
  73          */
  74         if ((dev->class >> 16) == PCI_BASE_CLASS_BRIDGE)
  75                 newcmd |= PCI_COMMAND_IO | PCI_COMMAND_MEMORY;
  76
  77
  78         if (newcmd != cmd) {
  79                 pr_info("PCI: enabling device %s (0x%04x -> 0x%04x)\n",
  80                         pci_name(dev), cmd, newcmd);
  81                 pci_write_config_word(dev, PCI_COMMAND, newcmd);
  82         }
  83         return 0;
  84 }
  85
  86 void pcibios_fixup_bus(struct pci_bus *bus)
  87 {
  88         struct pci_dev *dev;
  89
  90         list_for_each_entry(dev, &bus->devices, bus_list) {
  91                 pci_write_config_byte(dev, PCI_CACHE_LINE_SIZE, 8);
  92                 pci_write_config_byte(dev, PCI_LATENCY_TIMER, 32);
  93         }
  94 }
  95
  96 char *pcibios_setup(char *str)
  97 {
  98         return str;
  99 }
 100