120 lines
3.0 KiB
C
120 lines
3.0 KiB
C
/*
|
|
* ChromeOS platform support code. Glue layer between higher level functions
|
|
* and per-platform firmware interfaces.
|
|
*
|
|
* Copyright (C) 2010 The Chromium OS Authors
|
|
*
|
|
* 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; either version 2 of the License, or
|
|
* (at your option) any later version.
|
|
*
|
|
* 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., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
|
|
*/
|
|
|
|
#include <linux/types.h>
|
|
#include <linux/chromeos_platform.h>
|
|
#include <linux/module.h>
|
|
#include "chromeos.h"
|
|
|
|
static struct chromeos_vbc *chromeos_vbc_ptr;
|
|
|
|
static int vbc_read(u8 *buf, int buf_size);
|
|
static int vbc_write_byte(unsigned offset, u8 value);
|
|
|
|
/* the following defines are copied from
|
|
* vboot_reference:firmware/lib/vboot_nvstorage.c.
|
|
*/
|
|
#define RECOVERY_OFFSET 2
|
|
#define VBNV_RECOVERY_RW_INVALID_OS 0x43
|
|
|
|
int chromeos_set_need_recovery(void)
|
|
{
|
|
if (!chromeos_legacy_set_need_recovery())
|
|
return 0;
|
|
|
|
return vbc_write_byte(RECOVERY_OFFSET, VBNV_RECOVERY_RW_INVALID_OS);
|
|
}
|
|
|
|
/*
|
|
* Lifted from vboot_reference:firmware/lib/vboot_nvstorage.c and formatted.
|
|
*
|
|
* 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 u8 crc8(const u8 *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 (u8)(crc >> 8);
|
|
}
|
|
|
|
static int vbc_write_byte(unsigned offset, u8 value)
|
|
{
|
|
u8 buf[MAX_VBOOT_CONTEXT_BUFFER_SIZE];
|
|
ssize_t size;
|
|
|
|
if (!chromeos_vbc_ptr)
|
|
return -ENOSYS;
|
|
|
|
size = vbc_read(buf, sizeof(buf));
|
|
if (size <= 0)
|
|
return -EINVAL;
|
|
|
|
if (offset >= (size - 1))
|
|
return -EINVAL;
|
|
|
|
if (buf[offset] == value)
|
|
return 0;
|
|
|
|
buf[offset] = value;
|
|
buf[size - 1] = crc8(buf, size - 1);
|
|
|
|
return chromeos_vbc_ptr->write(buf, size);
|
|
}
|
|
|
|
/*
|
|
* Read vboot context and verify it. If everything checks out, return number
|
|
* of bytes in the vboot context buffer, -1 on any error (uninitialized
|
|
* subsystem, corrupted crc8 value, not enough room in the buffer, etc.).
|
|
*/
|
|
static int vbc_read(u8 *buf, int buf_size)
|
|
{
|
|
ssize_t size;
|
|
|
|
if (!chromeos_vbc_ptr)
|
|
return -ENOSYS;
|
|
|
|
size = chromeos_vbc_ptr->read(buf, buf_size);
|
|
if (size <= 0)
|
|
return -1;
|
|
|
|
if (buf[size - 1] != crc8(buf, size - 1)) {
|
|
pr_err("%s: vboot context contents corrupted\n", __func__);
|
|
return -1;
|
|
}
|
|
return size;
|
|
}
|
|
|
|
int chromeos_vbc_register(struct chromeos_vbc *chromeos_vbc)
|
|
{
|
|
chromeos_vbc_ptr = chromeos_vbc;
|
|
return 0;
|
|
}
|