1 /*****************************************************************************\
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>.
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.
14 * Please also read the file DISCLAIMER which is included in this software
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.
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.
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 \*****************************************************************************/
33 #include "cmos_lowlevel.h"
35 static int prepare_cmos_op_common(const cmos_entry_t * e);
37 /****************************************************************************
38 * prepare_cmos_op_common
40 * Perform a few checks common to both reads and writes.
41 ****************************************************************************/
42 static int prepare_cmos_op_common(const cmos_entry_t * e)
46 if (e->config == CMOS_ENTRY_RESERVED)
47 /* Access to reserved parameters is not permitted. */
48 return CMOS_OP_RESERVED;
50 if ((result = verify_cmos_op(e->bit, e->length, e->config)) != OK)
53 assert(e->length > 0);
57 /****************************************************************************
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)
68 if ((result = prepare_cmos_op_common(e)) != OK)
74 case CMOS_ENTRY_STRING:
84 /****************************************************************************
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)
96 unsigned long long out;
99 int negative, result, found_one;
101 if ((result = prepare_cmos_op_common(e)) != OK)
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)) {
111 if (!strncmp(q->text, value_str, CMOS_MAX_TEXT_LENGTH))
116 return CMOS_OP_NO_MATCHING_ENUM;
119 return CMOS_OP_BAD_ENUM_VALUE;
125 /* See if the first character of 'value_str' (excluding
126 * any initial whitespace) is a minus sign.
128 for (p = value_str; isspace(*p); p++) ;
129 negative = (*p == '-');
131 out = strtoull(value_str, (char **)&p, 0);
134 return CMOS_OP_INVALID_INT;
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.
141 return CMOS_OP_NEGATIVE_INT;
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;
158 if ((e->length < (8 * sizeof(*value))) && (out >= (1ull << e->length)))
159 return CMOS_OP_VALUE_TOO_WIDE;
165 /****************************************************************************
168 * Read the checksum for the coreboot parameters stored in CMOS and return
170 ****************************************************************************/
171 uint16_t cmos_checksum_read(void)
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;
181 /****************************************************************************
182 * cmos_checksum_write
184 * Set the checksum for the coreboot parameters stored in CMOS to
186 ****************************************************************************/
187 void cmos_checksum_write(uint16_t checksum)
189 unsigned char lo, hi;
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);
198 /****************************************************************************
199 * cmos_checksum_compute
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)
210 for (i = cmos_checksum_start; i <= cmos_checksum_end; i++)
211 sum += cmos_read_byte(i);
213 return ~((uint16_t) (sum & 0xffff));
216 /****************************************************************************
217 * cmos_checksum_verify
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)
224 uint16_t computed, actual;
227 computed = cmos_checksum_compute();
228 actual = cmos_checksum_read();
231 if (computed != actual) {
232 fprintf(stderr, "%s: Warning: Coreboot CMOS checksum is bad.\n",