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
  34 #include "pci.h"
  35
  36 static int
  37 skip_isa_ioresource_align(struct pci_dev *dev) {
  38
  39         if ((pci_probe & PCI_CAN_SKIP_ISA_ALIGN) &&
  40             !(dev->bus->bridge_ctl & PCI_BRIDGE_CTL_ISA))
  41                 return 1;
  42         return 0;
  43 }
  44
  45 /*
  46  * We need to avoid collisions with `mirrored' VGA ports
  47  * and other strange ISA hardware, so we always want the
  48  * addresses to be allocated in the 0x000-0x0ff region
  49  * modulo 0x400.
  50  *
  51  * Why? Because some silly external IO cards only decode
  52  * the low 10 bits of the IO address. The 0x00-0xff region
  53  * is reserved for motherboard devices that decode all 16
  54  * bits, so it's ok to allocate at, say, 0x2800-0x28ff,
  55  * but we want to try to avoid allocating at 0x2900-0x2bff
  56  * which might have be mirrored at 0x0100-0x03ff..
  57  */
  58 void
  59 pcibios_align_resource(void *data, struct resource *res,
  60                         resource_size_t size, resource_size_t align)
  61 {
  62         struct pci_dev *dev = data;
  63
  64         if (res->flags & IORESOURCE_IO) {
  65                 resource_size_t start = res->start;
  66
  67                 if (skip_isa_ioresource_align(dev))
  68                         return;
  69                 if (start & 0x300) {
  70                         start = (start + 0x3ff) & ~0x3ff;
  71                         res->start = start;
  72                 }
  73         }
  74 }
  75
  76
  77 /*
  78  *  Handle resources of PCI devices.  If the world were perfect, we could
  79  *  just allocate all the resource regions and do nothing more.  It isn't.
  80  *  On the other hand, we cannot just re-allocate all devices, as it would
  81  *  require us to know lots of host bridge internals.  So we attempt to
  82  *  keep as much of the original configuration as possible, but tweak it
  83  *  when it's found to be wrong.
  84  *
  85  *  Known BIOS problems we have to work around:
  86  *      - I/O or memory regions not configured
  87  *      - regions configured, but not enabled in the command register
  88  *      - bogus I/O addresses above 64K used
  89  *      - expansion ROMs left enabled (this may sound harmless, but given
  90  *        the fact the PCI specs explicitly allow address decoders to be
  91  *        shared between expansion ROMs and other resource regions, it's
  92  *        at least dangerous)
  93  *
  94  *  Our solution:
  95  *      (1) Allocate resources for all buses behind PCI-to-PCI bridges.
  96  *          This gives us fixed barriers on where we can allocate.
  97  *      (2) Allocate resources for all enabled devices.  If there is
  98  *          a collision, just mark the resource as unallocated. Also
  99  *          disable expansion ROMs during this step.
 100  *      (3) Try to allocate resources for disabled devices.  If the
 101  *          resources were assigned correctly, everything goes well,
 102  *          if they weren't, they won't disturb allocation of other
 103  *          resources.
 104  *      (4) Assign new addresses to resources which were either
 105  *          not configured at all or misconfigured.  If explicitly
 106  *          requested by the user, configure expansion ROM address
 107  *          as well.
 108  */
 109
 110 static void __init pcibios_allocate_bus_resources(struct list_head *bus_list)
 111 {
 112         struct pci_bus *bus;
 113         struct pci_dev *dev;
 114         int idx;
 115         struct resource *r, *pr;
 116
 117         /* Depth-First Search on bus tree */
 118         list_for_each_entry(bus, bus_list, node) {
 119                 if ((dev = bus->self)) {
 120                         for (idx = PCI_BRIDGE_RESOURCES;
 121                             idx < PCI_NUM_RESOURCES; idx++) {
 122                                 r = &dev->resource[idx];
 123                                 if (!r->flags)
 124                                         continue;
 125                                 pr = pci_find_parent_resource(dev, r);
 126                                 if (!r->start || !pr ||
 127                                     request_resource(pr, r) < 0) {
 128                                         printk(KERN_ERR "PCI: Cannot allocate "
 129                                                 "resource region %d "
 130                                                 "of bridge %s\n",
 131                                                 idx, pci_name(dev));
 132                                         /*
 133                                          * Something is wrong with the region.
 134                                          * Invalidate the resource to prevent
 135                                          * child resource allocations in this
 136                                          * range.
 137                                          */
 138                                         r->flags = 0;
 139                                 }
 140                         }
 141                 }
 142                 pcibios_allocate_bus_resources(&bus->children);
 143         }
 144 }
 145
 146 static void __init pcibios_allocate_resources(int pass)
 147 {
 148         struct pci_dev *dev = NULL;
 149         int idx, disabled;
 150         u16 command;
 151         struct resource *r, *pr;
 152
 153         for_each_pci_dev(dev) {
 154                 pci_read_config_word(dev, PCI_COMMAND, &command);
 155                 for (idx = 0; idx < PCI_ROM_RESOURCE; idx++) {
 156                         r = &dev->resource[idx];
 157                         if (r->parent)          /* Already allocated */
 158                                 continue;
 159                         if (!r->start)          /* Address not assigned at all */
 160                                 continue;
 161                         if (r->flags & IORESOURCE_IO)
 162                                 disabled = !(command & PCI_COMMAND_IO);
 163                         else
 164                                 disabled = !(command & PCI_COMMAND_MEMORY);
 165                         if (pass == disabled) {
 166                                 DBG("PCI: Resource %08lx-%08lx "
 167                                     "(f=%lx, d=%d, p=%d)\n",
 168                                     r->start, r->end, r->flags, disabled, pass);
 169                                 pr = pci_find_parent_resource(dev, r);
 170                                 if (!pr || request_resource(pr, r) < 0) {
 171                                         printk(KERN_ERR "PCI: Cannot allocate "
 172                                                 "resource region %d "
 173                                                 "of device %s\n",
 174                                                 idx, pci_name(dev));
 175                                         /* We'll assign a new address later */
 176                                         r->end -= r->start;
 177                                         r->start = 0;
 178                                 }
 179                         }
 180                 }
 181                 if (!pass) {
 182                         r = &dev->resource[PCI_ROM_RESOURCE];
 183                         if (r->flags & IORESOURCE_ROM_ENABLE) {
 184                                 /* Turn the ROM off, leave the resource region,
 185                                  * but keep it unregistered. */
 186                                 u32 reg;
 187                                 DBG("PCI: Switching off ROM of %s\n",
 188                                         pci_name(dev));
 189                                 r->flags &= ~IORESOURCE_ROM_ENABLE;
 190                                 pci_read_config_dword(dev,
 191                                                 dev->rom_base_reg, &reg);
 192                                 pci_write_config_dword(dev, dev->rom_base_reg,
 193                                                 reg & ~PCI_ROM_ADDRESS_ENABLE);
 194                         }
 195                 }
 196         }
 197 }
 198
 199 static int __init pcibios_assign_resources(void)
 200 {
 201         struct pci_dev *dev = NULL;
 202         struct resource *r, *pr;
 203
 204         if (!(pci_probe & PCI_ASSIGN_ROMS)) {
 205                 /*
 206                  * Try to use BIOS settings for ROMs, otherwise let
 207                  * pci_assign_unassigned_resources() allocate the new
 208                  * addresses.
 209                  */
 210                 for_each_pci_dev(dev) {
 211                         r = &dev->resource[PCI_ROM_RESOURCE];
 212                         if (!r->flags || !r->start)
 213                                 continue;
 214                         pr = pci_find_parent_resource(dev, r);
 215                         if (!pr || request_resource(pr, r) < 0) {
 216                                 r->end -= r->start;
 217                                 r->start = 0;
 218                         }
 219                 }
 220         }
 221
 222         pci_assign_unassigned_resources();
 223
 224         return 0;
 225 }
 226
 227 void __init pcibios_resource_survey(void)
 228 {
 229         DBG("PCI: Allocating resources\n");
 230         pcibios_allocate_bus_resources(&pci_root_buses);
 231         pcibios_allocate_resources(0);
 232         pcibios_allocate_resources(1);
 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 int pcibios_enable_resources(struct pci_dev *dev, int mask)
 242 {
 243         u16 cmd, old_cmd;
 244         int idx;
 245         struct resource *r;
 246
 247         pci_read_config_word(dev, PCI_COMMAND, &cmd);
 248         old_cmd = cmd;
 249         for (idx = 0; idx < PCI_NUM_RESOURCES; idx++) {
 250                 /* Only set up the requested stuff */
 251                 if (!(mask & (1 << idx)))
 252                         continue;
 253
 254                 r = &dev->resource[idx];
 255                 if (!(r->flags & (IORESOURCE_IO | IORESOURCE_MEM)))
 256                         continue;
 257                 if ((idx == PCI_ROM_RESOURCE) &&
 258                                 (!(r->flags & IORESOURCE_ROM_ENABLE)))
 259                         continue;
 260                 if (!r->start && r->end) {
 261                         printk(KERN_ERR "PCI: Device %s not available "
 262                                 "because of resource %d collisions\n",
 263                                 pci_name(dev), idx);
 264                         return -EINVAL;
 265                 }
 266                 if (r->flags & IORESOURCE_IO)
 267                         cmd |= PCI_COMMAND_IO;
 268                 if (r->flags & IORESOURCE_MEM)
 269                         cmd |= PCI_COMMAND_MEMORY;
 270         }
 271         if (cmd != old_cmd) {
 272                 printk("PCI: Enabling device %s (%04x -> %04x)\n",
 273                         pci_name(dev), old_cmd, cmd);
 274                 pci_write_config_word(dev, PCI_COMMAND, cmd);
 275         }
 276         return 0;
 277 }
 278
 279 /*
 280  *  If we set up a device for bus mastering, we need to check the latency
 281  *  timer as certain crappy BIOSes forget to set it properly.
 282  */
 283 unsigned int pcibios_max_latency = 255;
 284
 285 void pcibios_set_master(struct pci_dev *dev)
 286 {
 287         u8 lat;
 288         pci_read_config_byte(dev, PCI_LATENCY_TIMER, &lat);
 289         if (lat < 16)
 290                 lat = (64 <= pcibios_max_latency) ? 64 : pcibios_max_latency;
 291         else if (lat > pcibios_max_latency)
 292                 lat = pcibios_max_latency;
 293         else
 294                 return;
 295         printk(KERN_DEBUG "PCI: Setting latency timer of device %s to %d\n",
 296                 pci_name(dev), lat);
 297         pci_write_config_byte(dev, PCI_LATENCY_TIMER, lat);
 298 }
 299
 300 int pci_mmap_page_range(struct pci_dev *dev, struct vm_area_struct *vma,
 301                         enum pci_mmap_state mmap_state, int write_combine)
 302 {
 303         unsigned long prot;
 304
 305         /* I/O space cannot be accessed via normal processor loads and
 306          * stores on this platform.
 307          */
 308         if (mmap_state == pci_mmap_io)
 309                 return -EINVAL;
 310
 311         /* Leave vm_pgoff as-is, the PCI space address is the physical
 312          * address on this platform.
 313          */
 314         prot = pgprot_val(vma->vm_page_prot);
 315         if (boot_cpu_data.x86 > 3)
 316                 prot |= _PAGE_PCD | _PAGE_PWT;
 317         vma->vm_page_prot = __pgprot(prot);
 318
 319         /* Write-combine setting is ignored, it is changed via the mtrr
 320          * interfaces on this platform.
 321          */
 322         if (io_remap_pfn_range(vma, vma->vm_start, vma->vm_pgoff,
 323                                vma->vm_end - vma->vm_start,
 324                                vma->vm_page_prot))
 325                 return -EAGAIN;
 326
 327         return 0;
 328 }