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 static unsigned long rom_align;
  36
  37 #define ARRAY_SIZE(x) (sizeof(x)/sizeof(x[0]))
  38
  39 static void sigbus(int sig)
  40 {
  41         _sigbus = 1;
  42 }
  43
  44 static int probe_address8(const __u8 *ptr, __u8 *val)
  45 {
  46         int rc = 0;
  47
  48         *val = *ptr;
  49         if (_sigbus)
  50                 rc = -1;
  51         _sigbus = 0;
  52
  53         return rc;
  54 }
  55
  56 static int probe_address16(const __u16 *ptr, __u16 *val)
  57 {
  58         int rc = 0;
  59
  60         *val = *ptr;
  61         if (_sigbus)
  62                 rc = -1;
  63         _sigbus = 0;
  64
  65         return rc;
  66 }
  67
  68 void probe_roms_exit(void)
  69 {
  70         signal(SIGBUS, SIG_DFL);
  71         if (rom_fd >= 0) {
  72                 close(rom_fd);
  73                 rom_fd = -1;
  74         }
  75         if (rom_mem != MAP_FAILED) {
  76                 munmap(rom_mem, rom_len);
  77                 rom_mem = MAP_FAILED;
  78         }
  79 }
  80
  81 int probe_roms_init(unsigned long align)
  82 {
  83         int fd;
  84         int rc = 0;
  85
  86         /* valid values are 2048 and 512.  512 is for PCI-3.0 compliant
  87          * systems, or systems that do not have dangerous/legacy ISA
  88          * devices.  2048 should always be safe
  89          */
  90         if (align == 512 || align == 2048)
  91                 rom_align = align;
  92         else
  93                 return -1;
  94
  95         if (signal(SIGBUS, sigbus) == SIG_ERR)
  96                 rc = -1;
  97         if (rc == 0) {
  98                 fd = open("/dev/mem", O_RDONLY);
  99                 if (fd < 0)
 100                         rc = -1;
 101         }
 102         if (rc == 0) {
 103                 rom_mem = mmap(NULL, rom_len, PROT_READ, MAP_PRIVATE, fd, 0xc0000);
 104                 if (rom_mem == MAP_FAILED)
 105                         rc = -1;
 106         }
 107
 108         if (rc == 0)
 109                 rom_fd = fd;
 110         else
 111                 probe_roms_exit();
 112
 113         return rc;
 114 }
 115
 116 /**
 117  * isa_bus_to_virt - convert physical address to mmap'd region
 118  * @addr - address to convert
 119  *
 120  * Only valid between a successful call to probe_roms_init and the
 121  * corresponding probe_roms_exit
 122  */
 123 static void *isa_bus_to_virt(unsigned long addr)
 124 {
 125         return rom_mem + (addr - 0xc0000);
 126 }
 127
 128 struct resource {
 129         unsigned long start;
 130         unsigned long end;
 131         const char *name;
 132 };
 133
 134 static struct resource system_rom_resource = {
 135         .name   = "System ROM",
 136         .start  = 0xf0000,
 137         .end    = 0xfffff,
 138 };
 139
 140 static struct resource extension_rom_resource = {
 141         .name   = "Extension ROM",
 142         .start  = 0xe0000,
 143         .end    = 0xeffff,
 144 };
 145
 146 static struct resource adapter_rom_resources[] = { {
 147         .name   = "Adapter ROM",
 148         .start  = 0xc8000,
 149         .end    = 0,
 150 }, {
 151         .name   = "Adapter ROM",
 152         .start  = 0,
 153         .end    = 0,
 154 }, {
 155         .name   = "Adapter ROM",
 156         .start  = 0,
 157         .end    = 0,
 158 }, {
 159         .name   = "Adapter ROM",
 160         .start  = 0,
 161         .end    = 0,
 162 }, {
 163         .name   = "Adapter ROM",
 164         .start  = 0,
 165         .end    = 0,
 166 }, {
 167         .name   = "Adapter ROM",
 168         .start  = 0,
 169         .end    = 0,
 170 } };
 171
 172 static struct resource video_rom_resource = {
 173         .name   = "Video ROM",
 174         .start  = 0xc0000,
 175         .end    = 0xc7fff,
 176 };
 177
 178 #define ROMSIGNATURE 0xaa55
 179
 180 static int romsignature(const unsigned char *rom)
 181 {
 182         const unsigned short * const ptr = (const unsigned short *)rom;
 183         unsigned short sig = 0;
 184
 185         return probe_address16(ptr, &sig) == 0 && sig == ROMSIGNATURE;
 186 }
 187
 188 static int romchecksum(const unsigned char *rom, unsigned long length)
 189 {
 190         unsigned char sum, c;
 191
 192         for (sum = 0; length && probe_address8(rom++, &c) == 0; length--)
 193                 sum += c;
 194         return !length && !sum;
 195 }
 196
 197 int scan_adapter_roms(scan_fn fn)
 198 {
 199         /* let scan_fn examing each of the adapter roms found by probe_roms */
 200         int i;
 201         int found;
 202
 203         if (rom_fd < 0)
 204                 return 0;
 205
 206         found = 0;
 207         for (i = 0; i < ARRAY_SIZE(adapter_rom_resources); i++) {
 208                 struct resource *res = &adapter_rom_resources[i];
 209
 210                 if (res->start) {
 211                         found = fn(isa_bus_to_virt(res->start),
 212                                    isa_bus_to_virt(res->end));
 213                         if (found)
 214                                 break;
 215                 } else
 216                         break;
 217         }
 218
 219         return found;
 220 }
 221
 222 static unsigned long align(unsigned long addr, unsigned long alignment)
 223 {
 224         return (addr + alignment - 1) & ~(alignment - 1);
 225 }
 226
 227 void probe_roms(void)
 228 {
 229         const void *rom;
 230         unsigned long start, length, upper;
 231         unsigned char c;
 232         int i;
 233
 234         if (rom_fd < 0)
 235                 return;
 236
 237         /* video rom */
 238         upper = adapter_rom_resources[0].start;
 239         for (start = video_rom_resource.start; start < upper; start += rom_align) {
 240                 rom = isa_bus_to_virt(start);
 241                 if (!romsignature(rom))
 242                         continue;
 243
 244                 video_rom_resource.start = start;
 245
 246                 if (probe_address8(rom + 2, &c) != 0)
 247                         continue;
 248
 249                 /* 0 < length <= 0x7f * 512, historically */
 250                 length = c * 512;
 251
 252                 /* if checksum okay, trust length byte */
 253                 if (length && romchecksum(rom, length))
 254                         video_rom_resource.end = start + length - 1;
 255                 break;
 256         }
 257
 258         start = align(video_rom_resource.end + 1, rom_align);
 259         if (start < upper)
 260                 start = upper;
 261
 262         /* system rom */
 263         upper = system_rom_resource.start;
 264
 265         /* check for extension rom (ignore length byte!) */
 266         rom = isa_bus_to_virt(extension_rom_resource.start);
 267         if (romsignature(rom)) {
 268                 length = extension_rom_resource.end - extension_rom_resource.start + 1;
 269                 if (romchecksum(rom, length))
 270                         upper = extension_rom_resource.start;
 271         }
 272
 273         /* check for adapter roms on 2k boundaries */
 274         for (i = 0; i < ARRAY_SIZE(adapter_rom_resources) && start < upper; start += rom_align) {
 275                 rom = isa_bus_to_virt(start);
 276                 if (!romsignature(rom))
 277                         continue;
 278
 279                 if (probe_address8(rom + 2, &c) != 0)
 280                         continue;
 281
 282                 /* 0 < length <= 0x7f * 512, historically */
 283                 length = c * 512;
 284
 285                 /* but accept any length that fits if checksum okay */
 286                 if (!length || start + length > upper || !romchecksum(rom, length))
 287                         continue;
 288
 289                 adapter_rom_resources[i].start = start;
 290                 adapter_rom_resources[i].end = start + length - 1;
 291
 292                 start = adapter_rom_resources[i++].end & ~(rom_align - 1);
 293         }
 294 }
 295