arch/x86/pci/i386.c

   1 /*
   2  *      Low-Level PCI Access for i386 machines
   3  *
   4  * Copyright 1993, 1994 Drew Eckhardt
   5  *      Visionary Computing
   6  *      (Unix and Linux consulting and custom programming)
   7  *      Drew@Colorado.EDU
   8  *      +1 (303) 786-7975
   9  *
  10  * Drew's work was sponsored by:
  11  *      iX Multiuser Multitasking Magazine
  12  *      Hannover, Germany
  13  *      hm@ix.de
  14  *
  15  * Copyright 1997--2000 Martin Mares <mj@ucw.cz>
  16  *
  17  * For more information, please consult the following manuals (look at
  18  * http://www.pcisig.com/ for how to get them):
  19  *
  20  * PCI BIOS Specification
  21  * PCI Local Bus Specification
  22  * PCI to PCI Bridge Specification
  23  * PCI System Design Guide
  24  *
  25  */
  26
  27 #include <linux/types.h>
  28 #include <linux/kernel.h>
  29 #include <linux/pci.h>
  30 #include <linux/init.h>
  31 #include <linux/ioport.h>
  32 #include <linux/errno.h>
  33 #include <linux/bootmem.h>
  34
  35 #include <asm/pat.h>
  36 #include <asm/e820.h>
  37 #include <asm/pci_x86.h>
  38
  39
  40 static int
  41 skip_isa_ioresource_align(struct pci_dev *dev) {
  42
  43         if ((pci_probe & PCI_CAN_SKIP_ISA_ALIGN) &&
  44             !(dev->bus->bridge_ctl & PCI_BRIDGE_CTL_ISA))
  45                 return 1;
  46         return 0;
  47 }
  48
  49 /*
  50  * We need to avoid collisions with `mirrored' VGA ports
  51  * and other strange ISA hardware, so we always want the
  52  * addresses to be allocated in the 0x000-0x0ff region
  53  * modulo 0x400.
  54  *
  55  * Why? Because some silly external IO cards only decode
  56  * the low 10 bits of the IO address. The 0x00-0xff region
  57  * is reserved for motherboard devices that decode all 16
  58  * bits, so it's ok to allocate at, say, 0x2800-0x28ff,
  59  * but we want to try to avoid allocating at 0x2900-0x2bff
  60  * which might have be mirrored at 0x0100-0x03ff..
  61  */
  62 void
  63 pcibios_align_resource(void *data, struct resource *res,
  64                         resource_size_t size, resource_size_t align)
  65 {
  66         struct pci_dev *dev = data;
  67
  68         if (res->flags & IORESOURCE_IO) {
  69                 resource_size_t start = res->start;
  70
  71                 if (skip_isa_ioresource_align(dev))
  72                         return;
  73                 if (start & 0x300) {
  74                         start = (start + 0x3ff) & ~0x3ff;
  75                         res->start = start;
  76                 }
  77         }
  78 }
  79 EXPORT_SYMBOL(pcibios_align_resource);
  80
  81 /*
  82  *  Handle resources of PCI devices.  If the world were perfect, we could
  83  *  just allocate all the resource regions and do nothing more.  It isn't.
  84  *  On the other hand, we cannot just re-allocate all devices, as it would
  85  *  require us to know lots of host bridge internals.  So we attempt to
  86  *  keep as much of the original configuration as possible, but tweak it
  87  *  when it's found to be wrong.
  88  *
  89  *  Known BIOS problems we have to work around:
  90  *      - I/O or memory regions not configured
  91  *      - regions configured, but not enabled in the command register
  92  *      - bogus I/O addresses above 64K used
  93  *      - expansion ROMs left enabled (this may sound harmless, but given
  94  *        the fact the PCI specs explicitly allow address decoders to be
  95  *        shared between expansion ROMs and other resource regions, it's
  96  *        at least dangerous)
  97  *
  98  *  Our solution:
  99  *      (1) Allocate resources for all buses behind PCI-to-PCI bridges.
 100  *          This gives us fixed barriers on where we can allocate.
 101  *      (2) Allocate resources for all enabled devices.  If there is
 102  *          a collision, just mark the resource as unallocated. Also
 103  *          disable expansion ROMs during this step.
 104  *      (3) Try to allocate resources for disabled devices.  If the
 105  *          resources were assigned correctly, everything goes well,
 106  *          if they weren't, they won't disturb allocation of other
 107  *          resources.
 108  *      (4) Assign new addresses to resources which were either
 109  *          not configured at all or misconfigured.  If explicitly
 110  *          requested by the user, configure expansion ROM address
 111  *          as well.
 112  */
 113
 114 static void __init pcibios_allocate_bus_resources(struct list_head *bus_list)
 115 {
 116         struct pci_bus *bus;
 117         struct pci_dev *dev;
 118         int idx;
 119         struct resource *r, *pr;
 120
 121         /* Depth-First Search on bus tree */
 122         list_for_each_entry(bus, bus_list, node) {
 123                 if ((dev = bus->self)) {
 124                         for (idx = PCI_BRIDGE_RESOURCES;
 125                             idx < PCI_NUM_RESOURCES; idx++) {
 126                                 r = &dev->resource[idx];
 127                                 if (!r->flags)
 128                                         continue;
 129                                 pr = pci_find_parent_resource(dev, r);
 130                                 if (!r->start || !pr ||
 131                                     request_resource(pr, r) < 0) {
 132                                         dev_info(&dev->dev, "BAR %d: can't allocate resource\n", idx);
 133                                         /*
 134                                          * Something is wrong with the region.
 135                                          * Invalidate the resource to prevent
 136                                          * child resource allocations in this
 137                                          * range.
 138                                          */
 139                                         r->flags = 0;
 140                                 }
 141                         }
 142                 }
 143                 pcibios_allocate_bus_resources(&bus->children);
 144         }
 145 }
 146
 147 static void __init pcibios_allocate_resources(int pass)
 148 {
 149         struct pci_dev *dev = NULL;
 150         int idx, disabled;
 151         u16 command;
 152         struct resource *r, *pr;
 153
 154         for_each_pci_dev(dev) {
 155                 pci_read_config_word(dev, PCI_COMMAND, &command);
 156                 for (idx = 0; idx < PCI_ROM_RESOURCE; idx++) {
 157                         r = &dev->resource[idx];
 158                         if (r->parent)          /* Already allocated */
 159                                 continue;
 160                         if (!r->start)          /* Address not assigned at all */
 161                                 continue;
 162                         if (r->flags & IORESOURCE_IO)
 163                                 disabled = !(command & PCI_COMMAND_IO);
 164                         else
 165                                 disabled = !(command & PCI_COMMAND_MEMORY);
 166                         if (pass == disabled) {
 167                                 dev_dbg(&dev->dev, "resource %#08llx-%#08llx (f=%lx, d=%d, p=%d)\n",
 168                                         (unsigned long long) r->start,
 169                                         (unsigned long long) r->end,
 170                                         r->flags, disabled, pass);
 171                                 pr = pci_find_parent_resource(dev, r);
 172                                 if (!pr || request_resource(pr, r) < 0) {
 173                                         dev_info(&dev->dev, "BAR %d: can't allocate resource\n", idx);
 174                                         /* We'll assign a new address later */
 175                                         r->end -= r->start;
 176                                         r->start = 0;
 177                                 }
 178                         }
 179                 }
 180                 if (!pass) {
 181                         r = &dev->resource[PCI_ROM_RESOURCE];
 182                         if (r->flags & IORESOURCE_ROM_ENABLE) {
 183                                 /* Turn the ROM off, leave the resource region,
 184                                  * but keep it unregistered. */
 185                                 u32 reg;
 186                                 dev_dbg(&dev->dev, "disabling ROM\n");
 187                                 r->flags &= ~IORESOURCE_ROM_ENABLE;
 188                                 pci_read_config_dword(dev,
 189                                                 dev->rom_base_reg, &reg);
 190                                 pci_write_config_dword(dev, dev->rom_base_reg,
 191                                                 reg & ~PCI_ROM_ADDRESS_ENABLE);
 192                         }
 193                 }
 194         }
 195 }
 196
 197 static int __init pcibios_assign_resources(void)
 198 {
 199         struct pci_dev *dev = NULL;
 200         struct resource *r, *pr;
 201
 202         if (!(pci_probe & PCI_ASSIGN_ROMS)) {
 203                 /*
 204                  * Try to use BIOS settings for ROMs, otherwise let
 205                  * pci_assign_unassigned_resources() allocate the new
 206                  * addresses.
 207                  */
 208                 for_each_pci_dev(dev) {
 209                         r = &dev->resource[PCI_ROM_RESOURCE];
 210                         if (!r->flags || !r->start)
 211                                 continue;
 212                         pr = pci_find_parent_resource(dev, r);
 213                         if (!pr || request_resource(pr, r) < 0) {
 214                                 r->end -= r->start;
 215                                 r->start = 0;
 216                         }
 217                 }
 218         }
 219
 220         pci_assign_unassigned_resources();
 221
 222         return 0;
 223 }
 224
 225 void __init pcibios_resource_survey(void)
 226 {
 227         DBG("PCI: Allocating resources\n");
 228         pcibios_allocate_bus_resources(&pci_root_buses);
 229         pcibios_allocate_resources(0);
 230         pcibios_allocate_resources(1);
 231
 232         e820_reserve_resources_late();
 233 }
 234
 235 /**
 236  * called in fs_initcall (one below subsys_initcall),
 237  * give a chance for motherboard reserve resources
 238  */
 239 fs_initcall(pcibios_assign_resources);
 240
 241 /*
 242  *  If we set up a device for bus mastering, we need to check the latency
 243  *  timer as certain crappy BIOSes forget to set it properly.
 244  */
 245 unsigned int pcibios_max_latency = 255;
 246
 247 void pcibios_set_master(struct pci_dev *dev)
 248 {
 249         u8 lat;
 250         pci_read_config_byte(dev, PCI_LATENCY_TIMER, &lat);
 251         if (lat < 16)
 252                 lat = (64 <= pcibios_max_latency) ? 64 : pcibios_max_latency;
 253         else if (lat > pcibios_max_latency)
 254                 lat = pcibios_max_latency;
 255         else
 256                 return;
 257         dev_printk(KERN_DEBUG, &dev->dev, "setting latency timer to %d\n", lat);
 258         pci_write_config_byte(dev, PCI_LATENCY_TIMER, lat);
 259 }
 260
 261 static struct vm_operations_struct pci_mmap_ops = {
 262         .access = generic_access_phys,
 263 };
 264
 265 int pci_mmap_page_range(struct pci_dev *dev, struct vm_area_struct *vma,
 266                         enum pci_mmap_state mmap_state, int write_combine)
 267 {
 268         unsigned long prot;
 269
 270         /* I/O space cannot be accessed via normal processor loads and
 271          * stores on this platform.
 272          */
 273         if (mmap_state == pci_mmap_io)
 274                 return -EINVAL;
 275
 276         prot = pgprot_val(vma->vm_page_prot);
 277         if (pat_enabled && write_combine)
 278                 prot |= _PAGE_CACHE_WC;
 279         else if (pat_enabled || boot_cpu_data.x86 > 3)
 280                 /*
 281                  * ioremap() and ioremap_nocache() defaults to UC MINUS for now.
 282                  * To avoid attribute conflicts, request UC MINUS here
 283                  * aswell.
 284                  */
 285                 prot |= _PAGE_CACHE_UC_MINUS;
 286
 287         vma->vm_page_prot = __pgprot(prot);
 288
 289         if (io_remap_pfn_range(vma, vma->vm_start, vma->vm_pgoff,
 290                                vma->vm_end - vma->vm_start,
 291                                vma->vm_page_prot))
 292                 return -EAGAIN;
 293
 294         vma->vm_ops = &pci_mmap_ops;
 295
 296         return 0;
 297 }