util/nvramtool/cmos_lowlevel.c

   1 /*****************************************************************************\
   2  * cmos_lowlevel.c
   3  *****************************************************************************
   4  *  Copyright (C) 2002-2005 The Regents of the University of California.
   5  *  Produced at the Lawrence Livermore National Laboratory.
   6  *  Written by David S. Peterson <dsp@llnl.gov> <dave_peterson@pobox.com>.
   7  *  UCRL-CODE-2003-012
   8  *  All rights reserved.
   9  *
  10  *  This file is part of nvramtool, a utility for reading/writing coreboot
  11  *  parameters and displaying information from the coreboot table.
  12  *  For details, see http://coreboot.org/nvramtool.
  13  *
  14  *  Please also read the file DISCLAIMER which is included in this software
  15  *  distribution.
  16  *
  17  *  This program is free software; you can redistribute it and/or modify it
  18  *  under the terms of the GNU General Public License (as published by the
  19  *  Free Software Foundation) version 2, dated June 1991.
  20  *
  21  *  This program is distributed in the hope that it will be useful, but
  22  *  WITHOUT ANY WARRANTY; without even the IMPLIED WARRANTY OF
  23  *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the terms and
  24  *  conditions of the GNU General Public License for more details.
  25  *
  26  *  You should have received a copy of the GNU General Public License along
  27  *  with this program; if not, write to the Free Software Foundation, Inc.,
  28  *  51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
  29 \*****************************************************************************/
  30
  31 #if defined(__FreeBSD__)
  32 #include <fcntl.h>
  33 #include <unistd.h>
  34 #endif
  35
  36 #include "common.h"
  37 #include "cmos_lowlevel.h"
  38
  39 typedef struct {
  40         unsigned byte_index;
  41         unsigned bit_offset;
  42 } cmos_bit_op_location_t;
  43
  44 static unsigned cmos_bit_op_strategy(unsigned bit, unsigned bits_left,
  45                                      cmos_bit_op_location_t * where);
  46 static unsigned char cmos_read_bits(const cmos_bit_op_location_t * where,
  47                                     unsigned nr_bits);
  48 static void cmos_write_bits(const cmos_bit_op_location_t * where,
  49                             unsigned nr_bits, unsigned char value);
  50 static unsigned char get_bits(unsigned long long value, unsigned bit,
  51                               unsigned nr_bits);
  52 static void put_bits(unsigned char value, unsigned bit, unsigned nr_bits,
  53                      unsigned long long *result);
  54
  55 /****************************************************************************
  56  * get_bits
  57  *
  58  * Extract a value 'nr_bits' bits wide starting at bit position 'bit' from
  59  * 'value' and return the result.  It is assumed that 'nr_bits' is at most 8.
  60  ****************************************************************************/
  61 static inline unsigned char get_bits(unsigned long long value, unsigned bit,
  62                                      unsigned nr_bits)
  63 {
  64         return (value >> bit) & ((unsigned char)((1 << nr_bits) - 1));
  65 }
  66
  67 /****************************************************************************
  68  * put_bits
  69  *
  70  * Extract the low order 'nr_bits' bits from 'value' and store them in the
  71  * value pointed to by 'result' starting at bit position 'bit'.  The bit
  72  * positions in 'result' where the result is stored are assumed to be
  73  * initially zero.
  74  ****************************************************************************/
  75 static inline void put_bits(unsigned char value, unsigned bit,
  76                             unsigned nr_bits, unsigned long long *result)
  77 {
  78         *result += ((unsigned long long)(value &
  79                                 ((unsigned char)((1 << nr_bits) - 1)))) << bit;
  80 }
  81
  82 /****************************************************************************
  83  * cmos_read
  84  *
  85  * Read value from nonvolatile RAM at position given by 'bit' and 'length'
  86  * and return this value.  The I/O privilege level of the currently executing
  87  * process must be set appropriately.
  88  ****************************************************************************/
  89 unsigned long long cmos_read(const cmos_entry_t * e)
  90 {
  91         cmos_bit_op_location_t where;
  92         unsigned bit = e->bit, length = e->length;
  93         unsigned next_bit, bits_left, nr_bits;
  94         unsigned long long result = 0;
  95         unsigned char value;
  96
  97         assert(!verify_cmos_op(bit, length, e->config));
  98         result = 0;
  99
 100         if (e->config == CMOS_ENTRY_STRING) {
 101                 char *newstring = calloc(1, (length + 7) / 8);
 102                 unsigned usize = (8 * sizeof(unsigned long long));
 103
 104                 if (!newstring) {
 105                         out_of_memory();
 106                 }
 107
 108                 for (next_bit = 0, bits_left = length;
 109                      bits_left; next_bit += nr_bits, bits_left -= nr_bits) {
 110                         nr_bits = cmos_bit_op_strategy(bit + next_bit,
 111                                    bits_left > usize ? usize : bits_left, &where);
 112                         value = cmos_read_bits(&where, nr_bits);
 113                         put_bits(value, next_bit % usize, nr_bits,
 114                                  &((unsigned long long *)newstring)[next_bit /
 115                                                                     usize]);
 116                         result = (unsigned long)newstring;
 117                 }
 118         } else {
 119                 for (next_bit = 0, bits_left = length;
 120                      bits_left; next_bit += nr_bits, bits_left -= nr_bits) {
 121                         nr_bits =
 122                             cmos_bit_op_strategy(bit + next_bit, bits_left,
 123                                                  &where);
 124                         value = cmos_read_bits(&where, nr_bits);
 125                         put_bits(value, next_bit, nr_bits, &result);
 126                 }
 127         }
 128
 129         return result;
 130 }
 131
 132 /****************************************************************************
 133  * cmos_write
 134  *
 135  * Write 'data' to nonvolatile RAM at position given by 'bit' and 'length'.
 136  * The I/O privilege level of the currently executing process must be set
 137  * appropriately.
 138  ****************************************************************************/
 139 void cmos_write(const cmos_entry_t * e, unsigned long long value)
 140 {
 141         cmos_bit_op_location_t where;
 142         unsigned bit = e->bit, length = e->length;
 143         unsigned next_bit, bits_left, nr_bits;
 144
 145         assert(!verify_cmos_op(bit, length, e->config));
 146
 147         if (e->config == CMOS_ENTRY_STRING) {
 148                 unsigned long long *data =
 149                     (unsigned long long *)(unsigned long)value;
 150                 unsigned usize = (8 * sizeof(unsigned long long));
 151
 152                 for (next_bit = 0, bits_left = length;
 153                      bits_left; next_bit += nr_bits, bits_left -= nr_bits) {
 154                         nr_bits = cmos_bit_op_strategy(bit + next_bit,
 155                                         bits_left > usize ? usize : bits_left,
 156                                         &where);
 157                         value = data[next_bit / usize];
 158                         cmos_write_bits(&where, nr_bits,
 159                                 get_bits(value, next_bit % usize, nr_bits));
 160                 }
 161         } else {
 162                 for (next_bit = 0, bits_left = length;
 163                      bits_left; next_bit += nr_bits, bits_left -= nr_bits) {
 164                         nr_bits = cmos_bit_op_strategy(bit + next_bit,
 165                                         bits_left, &where);
 166                         cmos_write_bits(&where, nr_bits,
 167                                         get_bits(value, next_bit, nr_bits));
 168                 }
 169         }
 170 }
 171
 172 /****************************************************************************
 173  * cmos_read_byte
 174  *
 175  * Read a byte from nonvolatile RAM at a position given by 'index' and return
 176  * the result.  An 'index' value of 0 represents the first byte of
 177  * nonvolatile RAM.
 178  *
 179  * Note: the first 14 bytes of nonvolatile RAM provide an interface to the
 180  *       real time clock.
 181  ****************************************************************************/
 182 unsigned char cmos_read_byte(unsigned index)
 183 {
 184         unsigned short port_0, port_1;
 185
 186         assert(!verify_cmos_byte_index(index));
 187
 188         if (index < 128) {
 189                 port_0 = 0x70;
 190                 port_1 = 0x71;
 191         } else {
 192                 port_0 = 0x72;
 193                 port_1 = 0x73;
 194         }
 195
 196         OUTB(index, port_0);
 197         return INB(port_1);
 198 }
 199
 200 /****************************************************************************
 201  * cmos_write_byte
 202  *
 203  * Write 'value' to nonvolatile RAM at a position given by 'index'.  An
 204  * 'index' of 0 represents the first byte of nonvolatile RAM.
 205  *
 206  * Note: the first 14 bytes of nonvolatile RAM provide an interface to the
 207  *       real time clock.  Writing to any of these bytes will therefore
 208  *       affect its functioning.
 209  ****************************************************************************/
 210 void cmos_write_byte(unsigned index, unsigned char value)
 211 {
 212         unsigned short port_0, port_1;
 213
 214         assert(!verify_cmos_byte_index(index));
 215
 216         if (index < 128) {
 217                 port_0 = 0x70;
 218                 port_1 = 0x71;
 219         } else {
 220                 port_0 = 0x72;
 221                 port_1 = 0x73;
 222         }
 223
 224         OUTB(index, port_0);
 225         OUTB(value, port_1);
 226 }
 227
 228 /****************************************************************************
 229  * cmos_read_all
 230  *
 231  * Read all contents of CMOS memory into array 'data'.  The first 14 bytes of
 232  * 'data' are set to zero since this corresponds to the real time clock area.
 233  ****************************************************************************/
 234 void cmos_read_all(unsigned char data[])
 235 {
 236         unsigned i;
 237
 238         for (i = 0; i < CMOS_RTC_AREA_SIZE; i++)
 239                 data[i] = 0;
 240
 241         for (; i < CMOS_SIZE; i++)
 242                 data[i] = cmos_read_byte(i);
 243 }
 244
 245 /****************************************************************************
 246  * cmos_write_all
 247  *
 248  * Update all of CMOS memory with the contents of array 'data'.  The first 14
 249  * bytes of 'data' are ignored since this corresponds to the real time clock
 250  * area.
 251  ****************************************************************************/
 252 void cmos_write_all(unsigned char data[])
 253 {
 254         unsigned i;
 255
 256         for (i = CMOS_RTC_AREA_SIZE; i < CMOS_SIZE; i++)
 257                 cmos_write_byte(i, data[i]);
 258 }
 259
 260 /****************************************************************************
 261  * set_iopl
 262  *
 263  * Set the I/O privilege level of the executing process.  Root privileges are
 264  * required for performing this action.  A sufficient I/O privilege level
 265  * allows the process to access x86 I/O address space and to disable/reenable
 266  * interrupts while executing in user space.  Messing with the I/O privilege
 267  * level is therefore somewhat dangerous.
 268  ****************************************************************************/
 269 void set_iopl(int level)
 270 {
 271 #if defined(__FreeBSD__)
 272         static int io_fd = -1;
 273 #endif
 274
 275         assert((level >= 0) && (level <= 3));
 276
 277 #if defined(__FreeBSD__)
 278         if (level == 0) {
 279                 if (io_fd != -1) {
 280                         close(io_fd);
 281                         io_fd = -1;
 282                 }
 283         } else {
 284                 if (io_fd == -1) {
 285                         io_fd = open("/dev/io", O_RDWR);
 286                         if (io_fd < 0) {
 287                                 perror("/dev/io");
 288                                 exit(1);
 289                         }
 290                 }
 291         }
 292 #else
 293         if (iopl(level)) {
 294                 fprintf(stderr, "%s: iopl() system call failed.  "
 295                         "You must be root to do this.\n", prog_name);
 296                 exit(1);
 297         }
 298 #endif
 299 }
 300
 301 /****************************************************************************
 302  * verify_cmos_op
 303  *
 304  * 'bit' represents a bit position in the nonvolatile RAM.  The first bit
 305  * (i.e. the lowest order bit of the first byte) of nonvolatile RAM is
 306  * labeled as bit 0.  'length' represents the width in bits of a value we
 307  * wish to read or write.  Perform sanity checking on 'bit' and 'length'.  If
 308  * no problems were encountered, return OK.  Else return an error code.
 309  ****************************************************************************/
 310 int verify_cmos_op(unsigned bit, unsigned length, cmos_entry_config_t config)
 311 {
 312         if ((bit >= (8 * CMOS_SIZE)) || ((bit + length) > (8 * CMOS_SIZE)))
 313                 return CMOS_AREA_OUT_OF_RANGE;
 314
 315         if (bit < (8 * CMOS_RTC_AREA_SIZE))
 316                 return CMOS_AREA_OVERLAPS_RTC;
 317
 318         if (config == CMOS_ENTRY_STRING)
 319                 return OK;
 320
 321         if (length > (8 * sizeof(unsigned long long)))
 322                 return CMOS_AREA_TOO_WIDE;
 323
 324         return OK;
 325 }
 326
 327 /****************************************************************************
 328  * cmos_bit_op_strategy
 329  *
 330  * Helper function used by cmos_read() and cmos_write() to determine which
 331  * bits to read or write next.
 332  ****************************************************************************/
 333 static unsigned cmos_bit_op_strategy(unsigned bit, unsigned bits_left,
 334                                      cmos_bit_op_location_t * where)
 335 {
 336         unsigned max_bits;
 337
 338         where->byte_index = bit >> 3;
 339         where->bit_offset = bit & 0x07;
 340         max_bits = 8 - where->bit_offset;
 341         return (bits_left > max_bits) ? max_bits : bits_left;
 342 }
 343
 344 /****************************************************************************
 345  * cmos_read_bits
 346  *
 347  * Read a chunk of bits from a byte location within CMOS memory.  Return the
 348  * value represented by the chunk of bits.
 349  ****************************************************************************/
 350 static unsigned char cmos_read_bits(const cmos_bit_op_location_t * where,
 351                                     unsigned nr_bits)
 352 {
 353         return (cmos_read_byte(where->byte_index) >> where->bit_offset) &
 354             ((unsigned char)((1 << nr_bits) - 1));
 355 }
 356
 357 /****************************************************************************
 358  * cmos_write_bits
 359  *
 360  * Write a chunk of bits (the low order 'nr_bits' bits of 'value') to an area
 361  * within a particular byte of CMOS memory.
 362  ****************************************************************************/
 363 static void cmos_write_bits(const cmos_bit_op_location_t * where,
 364                             unsigned nr_bits, unsigned char value)
 365 {
 366         unsigned char n, mask;
 367
 368         if (nr_bits == 8) {
 369                 cmos_write_byte(where->byte_index, value);
 370                 return;
 371         }
 372
 373         n = cmos_read_byte(where->byte_index);
 374         mask = ((unsigned char)((1 << nr_bits) - 1)) << where->bit_offset;
 375         n = (n & ~mask) + ((value << where->bit_offset) & mask);
 376         cmos_write_byte(where->byte_index, n);
 377 }