src/drivers/elog/boot_count.c

   1 /*
   2  * This file is part of the coreboot project.
   3  *
   4  * Copyright (C) 2012 The ChromiumOS Authors.  All rights reserved.
   5  *
   6  * This program is free software; you can redistribute it and/or modify
   7  * it under the terms of the GNU General Public License as published by
   8  * the Free Software Foundation; version 2 of the License.
   9  *
  10  * This program is distributed in the hope that it will be useful,
  11  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  12  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  13  * GNU General Public License for more details.
  14  */
  15
  16 #include <console/console.h>
  17 #include <ip_checksum.h>
  18 #include <pc80/mc146818rtc.h>
  19 #include <stddef.h>
  20 #include <stdint.h>
  21 #include <elog.h>
  22
  23 /*
  24  * We need a region in CMOS to store the boot counter.
  25  *
  26  * This can either be declared as part of the option
  27  * table or statically defined in the board config.
  28  */
  29 #if CONFIG_USE_OPTION_TABLE
  30 # include "option_table.h"
  31 # define BOOT_COUNT_CMOS_OFFSET (CMOS_VSTART_boot_count_offset >> 3)
  32 #else
  33 # if defined(CONFIG_ELOG_BOOT_COUNT_CMOS_OFFSET) && CONFIG_ELOG_BOOT_COUNT_CMOS_OFFSET
  34 #  define BOOT_COUNT_CMOS_OFFSET CONFIG_ELOG_BOOT_COUNT_CMOS_OFFSET
  35 # else
  36 #  error "Must configure CONFIG_ELOG_BOOT_COUNT_CMOS_OFFSET"
  37 # endif
  38 #endif
  39
  40 #define BOOT_COUNT_SIGNATURE 0x4342 /* 'BC' */
  41
  42 struct boot_count {
  43         u16 signature;
  44         u32 count;
  45         u16 checksum;
  46 } __attribute__ ((packed));
  47
  48 /* Read and validate boot count structure from CMOS */
  49 static int boot_count_cmos_read(struct boot_count *bc)
  50 {
  51         u8 i, *p;
  52         u16 csum;
  53
  54         for (p = (u8*)bc, i = 0; i < sizeof(*bc); i++, p++)
  55                 *p = cmos_read(BOOT_COUNT_CMOS_OFFSET + i);
  56
  57         /* Verify signature */
  58         if (bc->signature != BOOT_COUNT_SIGNATURE) {
  59                 printk(BIOS_DEBUG, "Boot Count invalid signature\n");
  60                 return -1;
  61         }
  62
  63         /* Verify checksum over signature and counter only */
  64         csum = compute_ip_checksum(bc, offsetof(struct boot_count, checksum));
  65
  66         if (csum != bc->checksum) {
  67                 printk(BIOS_DEBUG, "Boot Count checksum mismatch\n");
  68                 return -1;
  69         }
  70
  71         return 0;
  72 }
  73
  74 /* Write boot count structure to CMOS */
  75 static void boot_count_cmos_write(struct boot_count *bc)
  76 {
  77         u8 i, *p;
  78
  79         /* Checksum over signature and counter only */
  80         bc->checksum = compute_ip_checksum(
  81                 bc, offsetof(struct boot_count, checksum));
  82
  83         for (p = (u8*)bc, i = 0; i < sizeof(*bc); i++, p++)
  84                 cmos_write(*p, BOOT_COUNT_CMOS_OFFSET + i);
  85 }
  86
  87 /* Increment boot count and return the new value */
  88 u32 boot_count_increment(void)
  89 {
  90         struct boot_count bc;
  91
  92         /* Read and increment boot count */
  93         if (boot_count_cmos_read(&bc) < 0) {
  94                 /* Structure invalid, re-initialize */
  95                 bc.signature = BOOT_COUNT_SIGNATURE;
  96                 bc.count = 0;
  97         }
  98
  99         /* Increment boot counter */
 100         bc.count++;
 101
 102         /* Write the new count to CMOS */
 103         boot_count_cmos_write(&bc);
 104
 105         printk(BIOS_DEBUG, "Boot Count incremented to %u\n", bc.count);
 106         return bc.count;
 107 }
 108
 109 /* Return the current boot count */
 110 u32 boot_count_read(void)
 111 {
 112         struct boot_count bc;
 113
 114         if (boot_count_cmos_read(&bc) < 0)
 115                 return 0;
 116
 117         return bc.count;
 118 }