probe_roms.c

   1 /*
   2  * probe_roms - scan for Adapter ROMS
   3  *
   4  * (based on linux-2.6:arch/x86/kernel/probe_roms_32.c)
   5  *
   6  * Copyright (C) 2008 Intel Corporation
   7  *
   8  * This program is free software; you can redistribute it and/or modify it
   9  * under the terms and conditions of the GNU General Public License,
  10  * version 2, as published by the Free Software Foundation.
  11  *
  12  * This program is distributed in the hope it will be useful, but WITHOUT
  13  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  14  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
  15  * more details.
  16  *
  17  * You should have received a copy of the GNU General Public License along with
  18  * this program; if not, write to the Free Software Foundation, Inc.,
  19  * 51 Franklin St - Fifth Floor, Boston, MA 02110-1301 USA.
  20  */
  21
  22 #include "probe_roms.h"
  23 #include <unistd.h>
  24 #include <signal.h>
  25 #include <fcntl.h>
  26 #include <sys/mman.h>
  27 #include <sys/stat.h>
  28 #include <sys/types.h>
  29 #include <asm/types.h>
  30
  31 static void *rom_mem = MAP_FAILED;
  32 static int rom_fd = -1;
  33 const static int rom_len = 0xf0000 - 0xc0000; /* option-rom memory region */
  34 static int _sigbus;
  35 #define ARRAY_SIZE(x) (sizeof(x)/sizeof(x[0]))
  36
  37 static void sigbus(int sig)
  38 {
  39         _sigbus = 1;
  40 }
  41
  42 static int probe_address8(const __u8 *ptr, __u8 *val)
  43 {
  44         int rc = 0;
  45
  46         *val = *ptr;
  47         if (_sigbus)
  48                 rc = -1;
  49         _sigbus = 0;
  50
  51         return rc;
  52 }
  53
  54 static int probe_address16(const __u16 *ptr, __u16 *val)
  55 {
  56         int rc = 0;
  57
  58         *val = *ptr;
  59         if (_sigbus)
  60                 rc = -1;
  61         _sigbus = 0;
  62
  63         return rc;
  64 }
  65
  66 void probe_roms_exit(void)
  67 {
  68         signal(SIGBUS, SIG_DFL);
  69         if (rom_fd >= 0) {
  70                 close(rom_fd);
  71                 rom_fd = -1;
  72         }
  73         if (rom_mem != MAP_FAILED) {
  74                 munmap(rom_mem, rom_len);
  75                 rom_mem = MAP_FAILED;
  76         }
  77 }
  78
  79 int probe_roms_init(void)
  80 {
  81         int fd;
  82         int rc = 0;
  83
  84         if (signal(SIGBUS, sigbus) == SIG_ERR)
  85                 rc = -1;
  86         if (rc == 0) {
  87                 fd = open("/dev/mem", O_RDONLY);
  88                 if (fd < 0)
  89                         rc = -1;
  90         }
  91         if (rc == 0) {
  92                 rom_mem = mmap(NULL, rom_len, PROT_READ, MAP_PRIVATE, fd, 0xc0000);
  93                 if (rom_mem == MAP_FAILED)
  94                         rc = -1;
  95         }
  96
  97         if (rc == 0)
  98                 rom_fd = fd;
  99         else
 100                 probe_roms_exit();
 101
 102         return rc;
 103 }
 104
 105 /**
 106  * isa_bus_to_virt - convert physical address to mmap'd region
 107  * @addr - address to convert
 108  *
 109  * Only valid between a successful call to probe_roms_init and the
 110  * corresponding probe_roms_exit
 111  */
 112 static void *isa_bus_to_virt(unsigned long addr)
 113 {
 114         return rom_mem + (addr - 0xc0000);
 115 }
 116
 117 struct resource {
 118         unsigned long start;
 119         unsigned long end;
 120         const char *name;
 121 };
 122
 123 static struct resource system_rom_resource = {
 124         .name   = "System ROM",
 125         .start  = 0xf0000,
 126         .end    = 0xfffff,
 127 };
 128
 129 static struct resource extension_rom_resource = {
 130         .name   = "Extension ROM",
 131         .start  = 0xe0000,
 132         .end    = 0xeffff,
 133 };
 134
 135 static struct resource adapter_rom_resources[] = { {
 136         .name   = "Adapter ROM",
 137         .start  = 0xc8000,
 138         .end    = 0,
 139 }, {
 140         .name   = "Adapter ROM",
 141         .start  = 0,
 142         .end    = 0,
 143 }, {
 144         .name   = "Adapter ROM",
 145         .start  = 0,
 146         .end    = 0,
 147 }, {
 148         .name   = "Adapter ROM",
 149         .start  = 0,
 150         .end    = 0,
 151 }, {
 152         .name   = "Adapter ROM",
 153         .start  = 0,
 154         .end    = 0,
 155 }, {
 156         .name   = "Adapter ROM",
 157         .start  = 0,
 158         .end    = 0,
 159 } };
 160
 161 static struct resource video_rom_resource = {
 162         .name   = "Video ROM",
 163         .start  = 0xc0000,
 164         .end    = 0xc7fff,
 165 };
 166
 167 #define ROMSIGNATURE 0xaa55
 168
 169 static int romsignature(const unsigned char *rom)
 170 {
 171         const unsigned short * const ptr = (const unsigned short *)rom;
 172         unsigned short sig = 0;
 173
 174         return probe_address16(ptr, &sig) == 0 && sig == ROMSIGNATURE;
 175 }
 176
 177 static int romchecksum(const unsigned char *rom, unsigned long length)
 178 {
 179         unsigned char sum, c;
 180
 181         for (sum = 0; length && probe_address8(rom++, &c) == 0; length--)
 182                 sum += c;
 183         return !length && !sum;
 184 }
 185
 186 int scan_adapter_roms(scan_fn fn)
 187 {
 188         /* let scan_fn examing each of the adapter roms found by probe_roms */
 189         int i;
 190         int found;
 191
 192         if (rom_fd < 0)
 193                 return 0;
 194
 195         found = 0;
 196         for (i = 0; i < ARRAY_SIZE(adapter_rom_resources); i++) {
 197                 struct resource *res = &adapter_rom_resources[i];
 198
 199                 if (res->start) {
 200                         found = fn(isa_bus_to_virt(res->start),
 201                                    isa_bus_to_virt(res->end));
 202                         if (found)
 203                                 break;
 204                 } else
 205                         break;
 206         }
 207
 208         return found;
 209 }
 210
 211 void probe_roms(void)
 212 {
 213         const void *rom;
 214         unsigned long start, length, upper;
 215         unsigned char c;
 216         int i;
 217
 218         if (rom_fd < 0)
 219                 return;
 220
 221         /* video rom */
 222         upper = adapter_rom_resources[0].start;
 223         for (start = video_rom_resource.start; start < upper; start += 2048) {
 224                 rom = isa_bus_to_virt(start);
 225                 if (!romsignature(rom))
 226                         continue;
 227
 228                 video_rom_resource.start = start;
 229
 230                 if (probe_address8(rom + 2, &c) != 0)
 231                         continue;
 232
 233                 /* 0 < length <= 0x7f * 512, historically */
 234                 length = c * 512;
 235
 236                 /* if checksum okay, trust length byte */
 237                 if (length && romchecksum(rom, length))
 238                         video_rom_resource.end = start + length - 1;
 239                 break;
 240         }
 241
 242         start = (video_rom_resource.end + 1 + 2047) & ~2047UL;
 243         if (start < upper)
 244                 start = upper;
 245
 246         /* system rom */
 247         upper = system_rom_resource.start;
 248
 249         /* check for extension rom (ignore length byte!) */
 250         rom = isa_bus_to_virt(extension_rom_resource.start);
 251         if (romsignature(rom)) {
 252                 length = extension_rom_resource.end - extension_rom_resource.start + 1;
 253                 if (romchecksum(rom, length))
 254                         upper = extension_rom_resource.start;
 255         }
 256
 257         /* check for adapter roms on 2k boundaries */
 258         for (i = 0; i < ARRAY_SIZE(adapter_rom_resources) && start < upper; start += 2048) {
 259                 rom = isa_bus_to_virt(start);
 260                 if (!romsignature(rom))
 261                         continue;
 262
 263                 if (probe_address8(rom + 2, &c) != 0)
 264                         continue;
 265
 266                 /* 0 < length <= 0x7f * 512, historically */
 267                 length = c * 512;
 268
 269                 /* but accept any length that fits if checksum okay */
 270                 if (!length || start + length > upper || !romchecksum(rom, length))
 271                         continue;
 272
 273                 adapter_rom_resources[i].start = start;
 274                 adapter_rom_resources[i].end = start + length - 1;
 275
 276                 start = adapter_rom_resources[i++].end & ~2047UL;
 277         }
 278 }
 279