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 #include <asm/io_apic.h>
  39
  40
  41 static int
  42 skip_isa_ioresource_align(struct pci_dev *dev) {
  43
  44         if ((pci_probe & PCI_CAN_SKIP_ISA_ALIGN) &&
  45             !(dev->bus->bridge_ctl & PCI_BRIDGE_CTL_ISA))
  46                 return 1;
  47         return 0;
  48 }
  49
  50 /*
  51  * We need to avoid collisions with `mirrored' VGA ports
  52  * and other strange ISA hardware, so we always want the
  53  * addresses to be allocated in the 0x000-0x0ff region
  54  * modulo 0x400.
  55  *
  56  * Why? Because some silly external IO cards only decode
  57  * the low 10 bits of the IO address. The 0x00-0xff region
  58  * is reserved for motherboard devices that decode all 16
  59  * bits, so it's ok to allocate at, say, 0x2800-0x28ff,
  60  * but we want to try to avoid allocating at 0x2900-0x2bff
  61  * which might have be mirrored at 0x0100-0x03ff..
  62  */
  63 resource_size_t
  64 pcibios_align_resource(void *data, const struct resource *res,
  65                         resource_size_t size, resource_size_t align)
  66 {
  67         struct pci_dev *dev = data;
  68         resource_size_t start = res->start;
  69
  70         if (res->flags & IORESOURCE_IO) {
  71                 if (skip_isa_ioresource_align(dev))
  72                         return start;
  73                 if (start & 0x300)
  74                         start = (start + 0x3ff) & ~0x3ff;
  75         } else if (res->flags & IORESOURCE_MEM) {
  76                 if (start < BIOS_END)
  77                         start = BIOS_END;
  78         }
  79         return start;
  80 }
  81 EXPORT_SYMBOL(pcibios_align_resource);
  82
  83 /*
  84  *  Handle resources of PCI devices.  If the world were perfect, we could
  85  *  just allocate all the resource regions and do nothing more.  It isn't.
  86  *  On the other hand, we cannot just re-allocate all devices, as it would
  87  *  require us to know lots of host bridge internals.  So we attempt to
  88  *  keep as much of the original configuration as possible, but tweak it
  89  *  when it's found to be wrong.
  90  *
  91  *  Known BIOS problems we have to work around:
  92  *      - I/O or memory regions not configured
  93  *      - regions configured, but not enabled in the command register
  94  *      - bogus I/O addresses above 64K used
  95  *      - expansion ROMs left enabled (this may sound harmless, but given
  96  *        the fact the PCI specs explicitly allow address decoders to be
  97  *        shared between expansion ROMs and other resource regions, it's
  98  *        at least dangerous)
  99  *
 100  *  Our solution:
 101  *      (1) Allocate resources for all buses behind PCI-to-PCI bridges.
 102  *          This gives us fixed barriers on where we can allocate.
 103  *      (2) Allocate resources for all enabled devices.  If there is
 104  *          a collision, just mark the resource as unallocated. Also
 105  *          disable expansion ROMs during this step.
 106  *      (3) Try to allocate resources for disabled devices.  If the
 107  *          resources were assigned correctly, everything goes well,
 108  *          if they weren't, they won't disturb allocation of other
 109  *          resources.
 110  *      (4) Assign new addresses to resources which were either
 111  *          not configured at all or misconfigured.  If explicitly
 112  *          requested by the user, configure expansion ROM address
 113  *          as well.
 114  */
 115
 116 static void __init pcibios_allocate_bus_resources(struct list_head *bus_list)
 117 {
 118         struct pci_bus *bus;
 119         struct pci_dev *dev;
 120         int idx;
 121         struct resource *r;
 122
 123         /* Depth-First Search on bus tree */
 124         list_for_each_entry(bus, bus_list, node) {
 125                 if ((dev = bus->self)) {
 126                         for (idx = PCI_BRIDGE_RESOURCES;
 127                             idx < PCI_NUM_RESOURCES; idx++) {
 128                                 r = &dev->resource[idx];
 129                                 if (!r->flags)
 130                                         continue;
 131                                 if (!r->start ||
 132                                     pci_claim_resource(dev, idx) < 0) {
 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 struct pci_check_idx_range {
 148         int start;
 149         int end;
 150 };
 151
 152 static void __init pcibios_allocate_resources(int pass)
 153 {
 154         struct pci_dev *dev = NULL;
 155         int idx, disabled, i;
 156         u16 command;
 157         struct resource *r;
 158
 159         struct pci_check_idx_range idx_range[] = {
 160                 { PCI_STD_RESOURCES, PCI_STD_RESOURCE_END },
 161 #ifdef CONFIG_PCI_IOV
 162                 { PCI_IOV_RESOURCES, PCI_IOV_RESOURCE_END },
 163 #endif
 164         };
 165
 166         for_each_pci_dev(dev) {
 167                 pci_read_config_word(dev, PCI_COMMAND, &command);
 168                 for (i = 0; i < ARRAY_SIZE(idx_range); i++)
 169                 for (idx = idx_range[i].start; idx <= idx_range[i].end; idx++) {
 170                         r = &dev->resource[idx];
 171                         if (r->parent)          /* Already allocated */
 172                                 continue;
 173                         if (!r->start)          /* Address not assigned at all */
 174                                 continue;
 175                         if (r->flags & IORESOURCE_IO)
 176                                 disabled = !(command & PCI_COMMAND_IO);
 177                         else
 178                                 disabled = !(command & PCI_COMMAND_MEMORY);
 179                         if (pass == disabled) {
 180                                 dev_dbg(&dev->dev,
 181                                         "BAR %d: reserving %pr (d=%d, p=%d)\n",
 182                                         idx, r, disabled, pass);
 183                                 if (pci_claim_resource(dev, idx) < 0) {
 184                                         /* We'll assign a new address later */
 185                                         r->end -= r->start;
 186                                         r->start = 0;
 187                                 }
 188                         }
 189                 }
 190                 if (!pass) {
 191                         r = &dev->resource[PCI_ROM_RESOURCE];
 192                         if (r->flags & IORESOURCE_ROM_ENABLE) {
 193                                 /* Turn the ROM off, leave the resource region,
 194                                  * but keep it unregistered. */
 195                                 u32 reg;
 196                                 dev_dbg(&dev->dev, "disabling ROM %pR\n", r);
 197                                 r->flags &= ~IORESOURCE_ROM_ENABLE;
 198                                 pci_read_config_dword(dev,
 199                                                 dev->rom_base_reg, &reg);
 200                                 pci_write_config_dword(dev, dev->rom_base_reg,
 201                                                 reg & ~PCI_ROM_ADDRESS_ENABLE);
 202                         }
 203                 }
 204         }
 205 }
 206
 207 static int __init pcibios_assign_resources(void)
 208 {
 209         struct pci_dev *dev = NULL;
 210         struct resource *r;
 211
 212         if (!(pci_probe & PCI_ASSIGN_ROMS)) {
 213                 /*
 214                  * Try to use BIOS settings for ROMs, otherwise let
 215                  * pci_assign_unassigned_resources() allocate the new
 216                  * addresses.
 217                  */
 218                 for_each_pci_dev(dev) {
 219                         r = &dev->resource[PCI_ROM_RESOURCE];
 220                         if (!r->flags || !r->start)
 221                                 continue;
 222                         if (pci_claim_resource(dev, PCI_ROM_RESOURCE) < 0) {
 223                                 r->end -= r->start;
 224                                 r->start = 0;
 225                         }
 226                 }
 227         }
 228
 229         pci_assign_unassigned_resources();
 230
 231         return 0;
 232 }
 233
 234 void __init pcibios_resource_survey(void)
 235 {
 236         DBG("PCI: Allocating resources\n");
 237         pcibios_allocate_bus_resources(&pci_root_buses);
 238         pcibios_allocate_resources(0);
 239         pcibios_allocate_resources(1);
 240
 241         e820_reserve_resources_late();
 242         /*
 243          * Insert the IO APIC resources after PCI initialization has
 244          * occured to handle IO APICS that are mapped in on a BAR in
 245          * PCI space, but before trying to assign unassigned pci res.
 246          */
 247         ioapic_insert_resources();
 248 }
 249
 250 /**
 251  * called in fs_initcall (one below subsys_initcall),
 252  * give a chance for motherboard reserve resources
 253  */
 254 fs_initcall(pcibios_assign_resources);
 255
 256 /*
 257  *  If we set up a device for bus mastering, we need to check the latency
 258  *  timer as certain crappy BIOSes forget to set it properly.
 259  */
 260 unsigned int pcibios_max_latency = 255;
 261
 262 void pcibios_set_master(struct pci_dev *dev)
 263 {
 264         u8 lat;
 265         pci_read_config_byte(dev, PCI_LATENCY_TIMER, &lat);
 266         if (lat < 16)
 267                 lat = (64 <= pcibios_max_latency) ? 64 : pcibios_max_latency;
 268         else if (lat > pcibios_max_latency)
 269                 lat = pcibios_max_latency;
 270         else
 271                 return;
 272         dev_printk(KERN_DEBUG, &dev->dev, "setting latency timer to %d\n", lat);
 273         pci_write_config_byte(dev, PCI_LATENCY_TIMER, lat);
 274 }
 275
 276 static const struct vm_operations_struct pci_mmap_ops = {
 277         .access = generic_access_phys,
 278 };
 279
 280 int pci_mmap_page_range(struct pci_dev *dev, struct vm_area_struct *vma,
 281                         enum pci_mmap_state mmap_state, int write_combine)
 282 {
 283         unsigned long prot;
 284
 285         /* I/O space cannot be accessed via normal processor loads and
 286          * stores on this platform.
 287          */
 288         if (mmap_state == pci_mmap_io)
 289                 return -EINVAL;
 290
 291         prot = pgprot_val(vma->vm_page_prot);
 292
 293         /*
 294          * Return error if pat is not enabled and write_combine is requested.
 295          * Caller can followup with UC MINUS request and add a WC mtrr if there
 296          * is a free mtrr slot.
 297          */
 298         if (!pat_enabled && write_combine)
 299                 return -EINVAL;
 300
 301         if (pat_enabled && write_combine)
 302                 prot |= _PAGE_CACHE_WC;
 303         else if (pat_enabled || boot_cpu_data.x86 > 3)
 304                 /*
 305                  * ioremap() and ioremap_nocache() defaults to UC MINUS for now.
 306                  * To avoid attribute conflicts, request UC MINUS here
 307                  * aswell.
 308                  */
 309                 prot |= _PAGE_CACHE_UC_MINUS;
 310
 311         vma->vm_page_prot = __pgprot(prot);
 312
 313         if (io_remap_pfn_range(vma, vma->vm_start, vma->vm_pgoff,
 314                                vma->vm_end - vma->vm_start,
 315                                vma->vm_page_prot))
 316                 return -EAGAIN;
 317
 318         vma->vm_ops = &pci_mmap_ops;
 319
 320         return 0;
 321 }