src/drivers/elog/boot_count.c

   1 /* SPDX-License-Identifier: GPL-2.0-only */
   2
   3 #include <console/console.h>
   4 #include <ip_checksum.h>
   5 #include <pc80/mc146818rtc.h>
   6 #include <stdint.h>
   7 #include <elog.h>
   8
   9 /*
  10  * We need a region in CMOS to store the boot counter.
  11  *
  12  * This can either be declared as part of the option
  13  * table or statically defined in the board config.
  14  */
  15 #if CONFIG(USE_OPTION_TABLE)
  16 # include "option_table.h"
  17 # define BOOT_COUNT_CMOS_OFFSET (CMOS_VSTART_boot_count_offset >> 3)
  18 #else
  19 # if (CONFIG_ELOG_BOOT_COUNT_CMOS_OFFSET != 0)
  20 #  define BOOT_COUNT_CMOS_OFFSET CONFIG_ELOG_BOOT_COUNT_CMOS_OFFSET
  21 # else
  22 #  error "Must configure CONFIG_ELOG_BOOT_COUNT_CMOS_OFFSET"
  23 # endif
  24 #endif
  25
  26 #define BOOT_COUNT_SIGNATURE 0x4342 /* 'BC' */
  27
  28 struct boot_count {
  29         u16 signature;
  30         u32 count;
  31         u16 checksum;
  32 } __packed;
  33
  34 /* Read and validate boot count structure from CMOS */
  35 static int boot_count_cmos_read(struct boot_count *bc)
  36 {
  37         u8 i, *p;
  38         u16 csum;
  39
  40         for (p = (u8 *)bc, i = 0; i < sizeof(*bc); i++, p++)
  41                 *p = cmos_read(BOOT_COUNT_CMOS_OFFSET + i);
  42
  43         /* Verify signature */
  44         if (bc->signature != BOOT_COUNT_SIGNATURE) {
  45                 printk(BIOS_DEBUG, "Boot Count invalid signature\n");
  46                 return -1;
  47         }
  48
  49         /* Verify checksum over signature and counter only */
  50         csum = compute_ip_checksum(bc, offsetof(struct boot_count, checksum));
  51
  52         if (csum != bc->checksum) {
  53                 printk(BIOS_DEBUG, "Boot Count checksum mismatch\n");
  54                 return -1;
  55         }
  56
  57         return 0;
  58 }
  59
  60 /* Write boot count structure to CMOS */
  61 static void boot_count_cmos_write(struct boot_count *bc)
  62 {
  63         u8 i, *p;
  64
  65         /* Checksum over signature and counter only */
  66         bc->checksum = compute_ip_checksum(
  67                 bc, offsetof(struct boot_count, checksum));
  68
  69         for (p = (u8 *)bc, i = 0; i < sizeof(*bc); i++, p++)
  70                 cmos_write(*p, BOOT_COUNT_CMOS_OFFSET + i);
  71 }
  72
  73 /* Increment boot count and return the new value */
  74 u32 boot_count_increment(void)
  75 {
  76         struct boot_count bc;
  77
  78         /* Read and increment boot count */
  79         if (boot_count_cmos_read(&bc) < 0) {
  80                 /* Structure invalid, re-initialize */
  81                 bc.signature = BOOT_COUNT_SIGNATURE;
  82                 bc.count = 0;
  83         }
  84
  85         /* Increment boot counter */
  86         bc.count++;
  87
  88         /* Write the new count to CMOS */
  89         boot_count_cmos_write(&bc);
  90
  91         printk(BIOS_DEBUG, "Boot Count incremented to %u\n", bc.count);
  92         return bc.count;
  93 }
  94
  95 /* Return the current boot count */
  96 u32 boot_count_read(void)
  97 {
  98         struct boot_count bc;
  99
 100         if (boot_count_cmos_read(&bc) < 0)
 101                 return 0;
 102
 103         return bc.count;
 104 }