summaryrefslogtreecommitdiff
path: root/src/vendorcode/google/chromeos/vbnv_cmos.c
blob: fe5a04fae8d5c50f039496f6e7b3e6c79350474f (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
/*
 * This file is part of the coreboot project.
 *
 * Copyright (C) 2011 The ChromiumOS Authors.  All rights reserved.
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; version 2 of the License.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc.
 */

#include <types.h>
#include <string.h>
#include <cbmem.h>
#include <console/console.h>
#include <pc80/mc146818rtc.h>
#include <arch/early_variables.h>
#include "chromeos.h"
#if IS_ENABLED(CONFIG_VBOOT_VERIFY_FIRMWARE)
#include "vboot_handoff.h"
#endif
#include "vbnv_layout.h"

static int vbnv_initialized CAR_GLOBAL;
static uint8_t vbnv[CONFIG_VBNV_SIZE] CAR_GLOBAL;

/* Wrappers for accessing the variables marked as CAR_GLOBAL. */
static inline int is_vbnv_initialized(void)
{
	return car_get_var(vbnv_initialized);
}

static inline uint8_t *vbnv_data_addr(int index)
{
	uint8_t *vbnv_arr = car_get_var_ptr(vbnv);

	return &vbnv_arr[index];
}

static inline uint8_t vbnv_data(int index)
{
	return *vbnv_data_addr(index);
}

/* Return CRC-8 of the data, using x^8 + x^2 + x + 1 polynomial.  A
 * table-based algorithm would be faster, but for only 15 bytes isn't
 * worth the code size.
 */

static uint8_t crc8(const uint8_t * data, int len)
{
	unsigned crc = 0;
	int i, j;

	for (j = len; j; j--, data++) {
		crc ^= (*data << 8);
		for (i = 8; i; i--) {
			if (crc & 0x8000)
				crc ^= (0x1070 << 3);
			crc <<= 1;
		}
	}

	return (uint8_t) (crc >> 8);
}

void read_vbnv(uint8_t *vbnv_copy)
{
	int i;

	for (i = 0; i < CONFIG_VBNV_SIZE; i++)
		vbnv_copy[i] = cmos_read(CONFIG_VBNV_OFFSET + 14 + i);

	/* Check data for consistency */
	if ((HEADER_SIGNATURE != (vbnv_copy[HEADER_OFFSET] & HEADER_MASK))
	    || (crc8(vbnv_copy, CRC_OFFSET) != vbnv_copy[CRC_OFFSET])) {

		/* Data is inconsistent (bad CRC or header),
		 * so reset to defaults
		 */
		memset(vbnv_copy, 0, VBNV_BLOCK_SIZE);
		vbnv_copy[HEADER_OFFSET] =
		    (HEADER_SIGNATURE | HEADER_FIRMWARE_SETTINGS_RESET |
		     HEADER_KERNEL_SETTINGS_RESET);
	}
}

void save_vbnv(const uint8_t *vbnv_copy)
{
	int i;

	for (i = 0; i < CONFIG_VBNV_SIZE; i++)
		cmos_write(vbnv_copy[i], CONFIG_VBNV_OFFSET + 14 + i);
}


static void vbnv_setup(void)
{
	read_vbnv(vbnv_data_addr(0));
	car_set_var(vbnv_initialized, 1);
}

int get_recovery_mode_from_vbnv(void)
{
	if (!is_vbnv_initialized())
		vbnv_setup();
	return vbnv_data(RECOVERY_OFFSET);
}

int vboot_wants_oprom(void)
{
#if IS_ENABLED(CONFIG_VBOOT_VERIFY_FIRMWARE)
	struct vboot_handoff *vbho;

	/* First check if handoff structure flag exists and is set. */
	vbho = cbmem_find(CBMEM_ID_VBOOT_HANDOFF);
	if (vbho && vbho->init_params.flags & VB_INIT_FLAG_OPROM_LOADED)
		return 1;
#endif

	if (!is_vbnv_initialized())
		vbnv_setup();

	return (vbnv_data(BOOT_OFFSET) & BOOT_OPROM_NEEDED) ? 1 : 0;
}