util/nvramtool/cmos_ops.c

   1 /*****************************************************************************\
   2  * cmos_ops.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 #include "common.h"
  32 #include "cmos_ops.h"
  33 #include "cmos_lowlevel.h"
  34
  35 static int prepare_cmos_op_common(const cmos_entry_t * e);
  36
  37 /****************************************************************************
  38  * prepare_cmos_op_common
  39  *
  40  * Perform a few checks common to both reads and writes.
  41  ****************************************************************************/
  42 static int prepare_cmos_op_common(const cmos_entry_t * e)
  43 {
  44         int result;
  45
  46         if (e->config == CMOS_ENTRY_RESERVED)
  47                 /* Access to reserved parameters is not permitted. */
  48                 return CMOS_OP_RESERVED;
  49
  50         if ((result = verify_cmos_op(e->bit, e->length, e->config)) != OK)
  51                 return result;
  52
  53         assert(e->length > 0);
  54         return OK;
  55 }
  56
  57 /****************************************************************************
  58  * prepare_cmos_read
  59  *
  60  * The caller wishes to read a CMOS parameter represented by 'e'.  Perform
  61  * sanity checking on 'e'.  If a problem was found with e, return an error
  62  * code.  Else return OK.
  63  ****************************************************************************/
  64 int prepare_cmos_read(const cmos_entry_t * e)
  65 {
  66         int result;
  67
  68         if ((result = prepare_cmos_op_common(e)) != OK)
  69                 return result;
  70
  71         switch (e->config) {
  72         case CMOS_ENTRY_ENUM:
  73         case CMOS_ENTRY_HEX:
  74         case CMOS_ENTRY_STRING:
  75                 break;
  76
  77         default:
  78                 BUG();
  79         }
  80
  81         return OK;
  82 }
  83
  84 /****************************************************************************
  85  * prepare_cmos_write
  86  *
  87  * The caller wishes to set a CMOS parameter represented by 'e' to a value
  88  * whose string representation is stored in 'value_str'.  Perform sanity
  89  * checking on 'value_str'.  On error, return an error code.  Else store the
  90  * numeric equivalent of 'value_str' in '*value' and return OK.
  91  ****************************************************************************/
  92 int prepare_cmos_write(const cmos_entry_t * e, const char value_str[],
  93                        unsigned long long *value)
  94 {
  95         const cmos_enum_t *q;
  96         unsigned long long out;
  97         const char *p;
  98         char *memory;
  99         int negative, result, found_one;
 100
 101         if ((result = prepare_cmos_op_common(e)) != OK)
 102                 return result;
 103
 104         switch (e->config) {
 105         case CMOS_ENTRY_ENUM:
 106                 /* Make sure the user's input corresponds to a valid option. */
 107                 for (q = first_cmos_enum_id(e->config_id), found_one = 0;
 108                      q != NULL; q = next_cmos_enum_id(q)) {
 109                         found_one = 1;
 110
 111                         if (!strncmp(q->text, value_str, CMOS_MAX_TEXT_LENGTH))
 112                                 break;
 113                 }
 114
 115                 if (!found_one)
 116                         return CMOS_OP_NO_MATCHING_ENUM;
 117
 118                 if (q == NULL)
 119                         return CMOS_OP_BAD_ENUM_VALUE;
 120
 121                 out = q->value;
 122                 break;
 123
 124         case CMOS_ENTRY_HEX:
 125                 /* See if the first character of 'value_str' (excluding
 126                  * any initial whitespace) is a minus sign.
 127                  */
 128                 for (p = value_str; isspace((int)(unsigned char)*p); p++) ;
 129                 negative = (*p == '-');
 130
 131                 out = strtoull(value_str, (char **)&p, 0);
 132
 133                 if (*p)
 134                         return CMOS_OP_INVALID_INT;
 135
 136                 /* If we get this far, the user specified a valid integer.
 137                  * However we do not currently support the use of negative
 138                  * numbers as CMOS parameter values.
 139                  */
 140                 if (negative)
 141                         return CMOS_OP_NEGATIVE_INT;
 142
 143                 break;
 144
 145         case CMOS_ENTRY_STRING:
 146                 if (e->length < (8 * strlen(value_str)))
 147                         return CMOS_OP_VALUE_TOO_WIDE;
 148                 memory = malloc(e->length / 8);
 149                 memset(memory, 0, e->length / 8);
 150                 strcpy(memory, value_str);
 151                 out = (unsigned long)memory;
 152                 break;
 153
 154         default:
 155                 BUG();
 156         }
 157
 158         if ((e->length < (8 * sizeof(*value))) && (out >= (1ull << e->length)))
 159                 return CMOS_OP_VALUE_TOO_WIDE;
 160
 161         *value = out;
 162         return OK;
 163 }
 164
 165 /****************************************************************************
 166  * cmos_checksum_read
 167  *
 168  * Read the checksum for the coreboot parameters stored in CMOS and return
 169  * this value.
 170  ****************************************************************************/
 171 uint16_t cmos_checksum_read(void)
 172 {
 173         uint16_t lo, hi;
 174
 175         /* The checksum is stored in a big-endian format. */
 176         hi = cmos_read_byte(cmos_checksum_index);
 177         lo = cmos_read_byte(cmos_checksum_index + 1);
 178         return (hi << 8) + lo;
 179 }
 180
 181 /****************************************************************************
 182  * cmos_checksum_write
 183  *
 184  * Set the checksum for the coreboot parameters stored in CMOS to
 185  * 'checksum'.
 186  ****************************************************************************/
 187 void cmos_checksum_write(uint16_t checksum)
 188 {
 189         unsigned char lo, hi;
 190
 191         /* The checksum is stored in a big-endian format. */
 192         hi = (unsigned char)(checksum >> 8);
 193         lo = (unsigned char)(checksum & 0x00ff);
 194         cmos_write_byte(cmos_checksum_index, hi);
 195         cmos_write_byte(cmos_checksum_index + 1, lo);
 196 }
 197
 198 /****************************************************************************
 199  * cmos_checksum_compute
 200  *
 201  * Compute a checksum for the coreboot parameter values currently stored in
 202  * CMOS and return this checksum.
 203  ****************************************************************************/
 204 uint16_t cmos_checksum_compute(void)
 205 {
 206         unsigned i, sum;
 207
 208         sum = 0;
 209
 210         for (i = cmos_checksum_start; i <= cmos_checksum_end; i++)
 211                 sum += cmos_read_byte(i);
 212
 213         return (uint16_t)(sum & 0xffff);
 214 }
 215
 216 /****************************************************************************
 217  * cmos_checksum_verify
 218  *
 219  * Verify that the coreboot CMOS checksum is valid.  If checksum is not
 220  * valid then print warning message and exit.
 221  ****************************************************************************/
 222 void cmos_checksum_verify(void)
 223 {
 224         uint16_t computed, actual;
 225
 226         set_iopl(3);
 227         computed = cmos_checksum_compute();
 228         actual = cmos_checksum_read();
 229         set_iopl(0);
 230
 231         if (computed != actual) {
 232                 fprintf(stderr, "%s: Warning: Coreboot CMOS checksum is bad.\n",
 233                         prog_name);
 234                 exit(1);
 235         }
 236 }