coreboot-kgpe-d16/util/nvramtool/cmos_lowlevel.c

300 lines
11 KiB
C

/*****************************************************************************\
* cmos_lowlevel.c
* $Id$
*****************************************************************************
* Copyright (C) 2002-2005 The Regents of the University of California.
* Produced at the Lawrence Livermore National Laboratory.
* Written by David S. Peterson <dsp@llnl.gov> <dave_peterson@pobox.com>.
* UCRL-CODE-2003-012
* All rights reserved.
*
* This file is part of nvramtool, a utility for reading/writing coreboot
* parameters and displaying information from the coreboot table.
* For details, see http://coreboot.org/nvramtool.
*
* Please also read the file DISCLAIMER which is included in this software
* distribution.
*
* 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, dated June 1991.
*
* 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 terms and
* conditions of 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 <sys/io.h>
#include "common.h"
#include "cmos_lowlevel.h"
typedef struct
{ unsigned byte_index;
unsigned bit_offset;
}
cmos_bit_op_location_t;
static unsigned cmos_bit_op_strategy (unsigned bit, unsigned bits_left,
cmos_bit_op_location_t *where);
static unsigned char cmos_read_bits (const cmos_bit_op_location_t *where,
unsigned nr_bits);
static void cmos_write_bits (const cmos_bit_op_location_t *where,
unsigned nr_bits, unsigned char value);
static unsigned char get_bits (unsigned long long value, unsigned bit,
unsigned nr_bits);
static void put_bits (unsigned char value, unsigned bit, unsigned nr_bits,
unsigned long long *result);
/****************************************************************************
* get_bits
*
* Extract a value 'nr_bits' bits wide starting at bit position 'bit' from
* 'value' and return the result. It is assumed that 'nr_bits' is at most 8.
****************************************************************************/
static inline unsigned char get_bits (unsigned long long value, unsigned bit,
unsigned nr_bits)
{ return (value >> bit) & ((unsigned char) ((1 << nr_bits) - 1)); }
/****************************************************************************
* put_bits
*
* Extract the low order 'nr_bits' bits from 'value' and store them in the
* value pointed to by 'result' starting at bit position 'bit'. The bit
* positions in 'result' where the result is stored are assumed to be
* initially zero.
****************************************************************************/
static inline void put_bits (unsigned char value, unsigned bit,
unsigned nr_bits, unsigned long long *result)
{ *result += (value & ((unsigned char) ((1 << nr_bits) - 1))) << bit; }
/****************************************************************************
* cmos_read
*
* Read value from nonvolatile RAM at position given by 'bit' and 'length'
* and return this value. The I/O privilege level of the currently executing
* process must be set appropriately.
****************************************************************************/
unsigned long long cmos_read (unsigned bit, unsigned length)
{ cmos_bit_op_location_t where;
unsigned next_bit, bits_left, nr_bits;
unsigned long long result;
unsigned char value;
assert(!verify_cmos_op(bit, length));
result = 0;
for (next_bit = 0, bits_left = length;
bits_left;
next_bit += nr_bits, bits_left -= nr_bits)
{ nr_bits = cmos_bit_op_strategy(bit + next_bit, bits_left, &where);
value = cmos_read_bits(&where, nr_bits);
put_bits(value, next_bit, nr_bits, &result);
}
return result;
}
/****************************************************************************
* cmos_write
*
* Write 'data' to nonvolatile RAM at position given by 'bit' and 'length'.
* The I/O privilege level of the currently executing process must be set
* appropriately.
****************************************************************************/
void cmos_write (unsigned bit, unsigned length, unsigned long long value)
{ cmos_bit_op_location_t where;
unsigned next_bit, bits_left, nr_bits;
assert(!verify_cmos_op(bit, length));
for (next_bit = 0, bits_left = length;
bits_left;
next_bit += nr_bits, bits_left -= nr_bits)
{ nr_bits = cmos_bit_op_strategy(bit + next_bit, bits_left, &where);
cmos_write_bits(&where, nr_bits, get_bits(value, next_bit, nr_bits));
}
}
/****************************************************************************
* cmos_read_byte
*
* Read a byte from nonvolatile RAM at a position given by 'index' and return
* the result. An 'index' value of 0 represents the first byte of
* nonvolatile RAM.
*
* Note: the first 14 bytes of nonvolatile RAM provide an interface to the
* real time clock.
****************************************************************************/
unsigned char cmos_read_byte (unsigned index)
{ unsigned short port_0, port_1;
assert(!verify_cmos_byte_index(index));
if (index < 128)
{ port_0 = 0x70;
port_1 = 0x71;
}
else
{ port_0 = 0x72;
port_1 = 0x73;
}
outb(index, port_0);
return inb(port_1);
}
/****************************************************************************
* cmos_write_byte
*
* Write 'value' to nonvolatile RAM at a position given by 'index'. An
* 'index' of 0 represents the first byte of nonvolatile RAM.
*
* Note: the first 14 bytes of nonvolatile RAM provide an interface to the
* real time clock. Writing to any of these bytes will therefore
* affect its functioning.
****************************************************************************/
void cmos_write_byte (unsigned index, unsigned char value)
{ unsigned short port_0, port_1;
assert(!verify_cmos_byte_index(index));
if (index < 128)
{ port_0 = 0x70;
port_1 = 0x71;
}
else
{ port_0 = 0x72;
port_1 = 0x73;
}
outb(index, port_0);
outb(value, port_1);
}
/****************************************************************************
* cmos_read_all
*
* Read all contents of CMOS memory into array 'data'. The first 14 bytes of
* 'data' are set to zero since this corresponds to the real time clock area.
****************************************************************************/
void cmos_read_all (unsigned char data[])
{ unsigned i;
for (i = 0; i < CMOS_RTC_AREA_SIZE; i++)
data[i] = 0;
for (; i < CMOS_SIZE; i++)
data[i] = cmos_read_byte(i);
}
/****************************************************************************
* cmos_write_all
*
* Update all of CMOS memory with the contents of array 'data'. The first 14
* bytes of 'data' are ignored since this corresponds to the real time clock
* area.
****************************************************************************/
void cmos_write_all (unsigned char data[])
{ unsigned i;
for (i = CMOS_RTC_AREA_SIZE; i < CMOS_SIZE; i++)
cmos_write_byte(i, data[i]);
}
/****************************************************************************
* set_iopl
*
* Set the I/O privilege level of the executing process. Root privileges are
* required for performing this action. A sufficient I/O privilege level
* allows the process to access x86 I/O address space and to disable/reenable
* interrupts while executing in user space. Messing with the I/O privilege
* level is therefore somewhat dangerous.
****************************************************************************/
void set_iopl (int level)
{ assert((level >= 0) && (level <= 3));
if (iopl(level))
{ fprintf(stderr,
"%s: iopl() system call failed. You must be root to do "
"this.\n",
prog_name);
exit(1);
}
}
/****************************************************************************
* verify_cmos_op
*
* 'bit' represents a bit position in the nonvolatile RAM. The first bit
* (i.e. the lowest order bit of the first byte) of nonvolatile RAM is
* labeled as bit 0. 'length' represents the width in bits of a value we
* wish to read or write. Perform sanity checking on 'bit' and 'length'. If
* no problems were encountered, return OK. Else return an error code.
****************************************************************************/
int verify_cmos_op (unsigned bit, unsigned length)
{ if ((bit >= (8 * CMOS_SIZE)) || ((bit + length) > (8 * CMOS_SIZE)))
return CMOS_AREA_OUT_OF_RANGE;
if (bit < (8 * CMOS_RTC_AREA_SIZE))
return CMOS_AREA_OVERLAPS_RTC;
if (length > (8 * sizeof(unsigned long long)))
return CMOS_AREA_TOO_WIDE;
return OK;
}
/****************************************************************************
* cmos_bit_op_strategy
*
* Helper function used by cmos_read() and cmos_write() to determine which
* bits to read or write next.
****************************************************************************/
static unsigned cmos_bit_op_strategy (unsigned bit, unsigned bits_left,
cmos_bit_op_location_t *where)
{ unsigned max_bits;
where->byte_index = bit >> 3;
where->bit_offset = bit & 0x07;
max_bits = 8 - where->bit_offset;
return (bits_left > max_bits) ? max_bits : bits_left;
}
/****************************************************************************
* cmos_read_bits
*
* Read a chunk of bits from a byte location within CMOS memory. Return the
* value represented by the chunk of bits.
****************************************************************************/
static unsigned char cmos_read_bits (const cmos_bit_op_location_t *where,
unsigned nr_bits)
{ return (cmos_read_byte(where->byte_index) >> where->bit_offset) &
((unsigned char) ((1 << nr_bits) - 1));
}
/****************************************************************************
* cmos_write_bits
*
* Write a chunk of bits (the low order 'nr_bits' bits of 'value') to an area
* within a particular byte of CMOS memory.
****************************************************************************/
static void cmos_write_bits (const cmos_bit_op_location_t *where,
unsigned nr_bits, unsigned char value)
{ unsigned char n, mask;
if (nr_bits == 8)
{ cmos_write_byte(where->byte_index, value);
return;
}
n = cmos_read_byte(where->byte_index);
mask = ((unsigned char) ((1 << nr_bits) - 1)) << where->bit_offset;
n = (n & ~mask) + ((value << where->bit_offset) & mask);
cmos_write_byte(where->byte_index, n);
}