300 lines
11 KiB
C
300 lines
11 KiB
C
/*****************************************************************************\
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* cmos_lowlevel.c
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* $Id: cmos_lowlevel.c,v 1.3 2006/01/24 00:25:39 dsp_llnl Exp $
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*****************************************************************************
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* Copyright (C) 2002-2005 The Regents of the University of California.
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* Produced at the Lawrence Livermore National Laboratory.
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* Written by David S. Peterson <dsp@llnl.gov> <dave_peterson@pobox.com>.
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* UCRL-CODE-2003-012
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* All rights reserved.
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*
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* This file is part of lxbios, a utility for reading/writing coreboot
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* parameters and displaying information from the coreboot table.
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* For details, see <http://www.llnl.gov/linux/lxbios/>.
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*
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* Please also read the file DISCLAIMER which is included in this software
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* distribution.
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*
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* This program is free software; you can redistribute it and/or modify it
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* under the terms of the GNU General Public License (as published by the
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* Free Software Foundation) version 2, dated June 1991.
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*
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* This program is distributed in the hope that it will be useful, but
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* WITHOUT ANY WARRANTY; without even the IMPLIED WARRANTY OF
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the terms and
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* conditions of the GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License along
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* with this program; if not, write to the Free Software Foundation, Inc.,
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* 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA.
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\*****************************************************************************/
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#include <sys/io.h>
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#include "common.h"
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#include "cmos_lowlevel.h"
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typedef struct
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{ unsigned byte_index;
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unsigned bit_offset;
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}
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cmos_bit_op_location_t;
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static unsigned cmos_bit_op_strategy (unsigned bit, unsigned bits_left,
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cmos_bit_op_location_t *where);
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static unsigned char cmos_read_bits (const cmos_bit_op_location_t *where,
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unsigned nr_bits);
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static void cmos_write_bits (const cmos_bit_op_location_t *where,
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unsigned nr_bits, unsigned char value);
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static unsigned char get_bits (unsigned long long value, unsigned bit,
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unsigned nr_bits);
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static void put_bits (unsigned char value, unsigned bit, unsigned nr_bits,
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unsigned long long *result);
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/****************************************************************************
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* get_bits
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*
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* Extract a value 'nr_bits' bits wide starting at bit position 'bit' from
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* 'value' and return the result. It is assumed that 'nr_bits' is at most 8.
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****************************************************************************/
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static inline unsigned char get_bits (unsigned long long value, unsigned bit,
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unsigned nr_bits)
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{ return (value >> bit) & ((unsigned char) ((1 << nr_bits) - 1)); }
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/****************************************************************************
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* put_bits
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*
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* Extract the low order 'nr_bits' bits from 'value' and store them in the
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* value pointed to by 'result' starting at bit position 'bit'. The bit
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* positions in 'result' where the result is stored are assumed to be
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* initially zero.
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****************************************************************************/
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static inline void put_bits (unsigned char value, unsigned bit,
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unsigned nr_bits, unsigned long long *result)
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{ *result += (value & ((unsigned char) ((1 << nr_bits) - 1))) << bit; }
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/****************************************************************************
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* cmos_read
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*
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* Read value from nonvolatile RAM at position given by 'bit' and 'length'
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* and return this value. The I/O privilege level of the currently executing
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* process must be set appropriately.
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****************************************************************************/
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unsigned long long cmos_read (unsigned bit, unsigned length)
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{ cmos_bit_op_location_t where;
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unsigned next_bit, bits_left, nr_bits;
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unsigned long long result;
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unsigned char value;
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assert(!verify_cmos_op(bit, length));
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result = 0;
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for (next_bit = 0, bits_left = length;
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bits_left;
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next_bit += nr_bits, bits_left -= nr_bits)
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{ nr_bits = cmos_bit_op_strategy(bit + next_bit, bits_left, &where);
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value = cmos_read_bits(&where, nr_bits);
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put_bits(value, next_bit, nr_bits, &result);
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}
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return result;
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}
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/****************************************************************************
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* cmos_write
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*
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* Write 'data' to nonvolatile RAM at position given by 'bit' and 'length'.
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* The I/O privilege level of the currently executing process must be set
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* appropriately.
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****************************************************************************/
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void cmos_write (unsigned bit, unsigned length, unsigned long long value)
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{ cmos_bit_op_location_t where;
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unsigned next_bit, bits_left, nr_bits;
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assert(!verify_cmos_op(bit, length));
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for (next_bit = 0, bits_left = length;
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bits_left;
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next_bit += nr_bits, bits_left -= nr_bits)
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{ nr_bits = cmos_bit_op_strategy(bit + next_bit, bits_left, &where);
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cmos_write_bits(&where, nr_bits, get_bits(value, next_bit, nr_bits));
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}
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}
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/****************************************************************************
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* cmos_read_byte
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*
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* Read a byte from nonvolatile RAM at a position given by 'index' and return
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* the result. An 'index' value of 0 represents the first byte of
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* nonvolatile RAM.
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*
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* Note: the first 14 bytes of nonvolatile RAM provide an interface to the
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* real time clock.
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****************************************************************************/
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unsigned char cmos_read_byte (unsigned index)
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{ unsigned short port_0, port_1;
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assert(!verify_cmos_byte_index(index));
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if (index < 128)
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{ port_0 = 0x70;
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port_1 = 0x71;
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}
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else
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{ port_0 = 0x72;
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port_1 = 0x73;
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}
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outb(index, port_0);
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return inb(port_1);
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}
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/****************************************************************************
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* cmos_write_byte
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*
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* Write 'value' to nonvolatile RAM at a position given by 'index'. An
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* 'index' of 0 represents the first byte of nonvolatile RAM.
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*
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* Note: the first 14 bytes of nonvolatile RAM provide an interface to the
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* real time clock. Writing to any of these bytes will therefore
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* affect its functioning.
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****************************************************************************/
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void cmos_write_byte (unsigned index, unsigned char value)
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{ unsigned short port_0, port_1;
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assert(!verify_cmos_byte_index(index));
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if (index < 128)
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{ port_0 = 0x70;
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port_1 = 0x71;
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}
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else
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{ port_0 = 0x72;
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port_1 = 0x73;
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}
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outb(index, port_0);
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outb(value, port_1);
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}
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/****************************************************************************
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* cmos_read_all
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*
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* Read all contents of CMOS memory into array 'data'. The first 14 bytes of
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* 'data' are set to zero since this corresponds to the real time clock area.
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****************************************************************************/
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void cmos_read_all (unsigned char data[])
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{ unsigned i;
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for (i = 0; i < CMOS_RTC_AREA_SIZE; i++)
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data[i] = 0;
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for (; i < CMOS_SIZE; i++)
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data[i] = cmos_read_byte(i);
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}
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/****************************************************************************
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* cmos_write_all
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*
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* Update all of CMOS memory with the contents of array 'data'. The first 14
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* bytes of 'data' are ignored since this corresponds to the real time clock
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* area.
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****************************************************************************/
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void cmos_write_all (unsigned char data[])
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{ unsigned i;
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for (i = CMOS_RTC_AREA_SIZE; i < CMOS_SIZE; i++)
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cmos_write_byte(i, data[i]);
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}
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/****************************************************************************
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* set_iopl
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*
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* Set the I/O privilege level of the executing process. Root privileges are
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* required for performing this action. A sufficient I/O privilege level
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* allows the process to access x86 I/O address space and to disable/reenable
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* interrupts while executing in user space. Messing with the I/O privilege
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* level is therefore somewhat dangerous.
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****************************************************************************/
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void set_iopl (int level)
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{ assert((level >= 0) && (level <= 3));
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if (iopl(level))
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{ fprintf(stderr,
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"%s: iopl() system call failed. You must be root to do "
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"this.\n",
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prog_name);
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exit(1);
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}
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}
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/****************************************************************************
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* verify_cmos_op
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*
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* 'bit' represents a bit position in the nonvolatile RAM. The first bit
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* (i.e. the lowest order bit of the first byte) of nonvolatile RAM is
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* labeled as bit 0. 'length' represents the width in bits of a value we
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* wish to read or write. Perform sanity checking on 'bit' and 'length'. If
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* no problems were encountered, return OK. Else return an error code.
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****************************************************************************/
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int verify_cmos_op (unsigned bit, unsigned length)
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{ if ((bit >= (8 * CMOS_SIZE)) || ((bit + length) > (8 * CMOS_SIZE)))
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return CMOS_AREA_OUT_OF_RANGE;
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if (bit < (8 * CMOS_RTC_AREA_SIZE))
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return CMOS_AREA_OVERLAPS_RTC;
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if (length > (8 * sizeof(unsigned long long)))
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return CMOS_AREA_TOO_WIDE;
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return OK;
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}
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/****************************************************************************
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* cmos_bit_op_strategy
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*
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* Helper function used by cmos_read() and cmos_write() to determine which
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* bits to read or write next.
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****************************************************************************/
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static unsigned cmos_bit_op_strategy (unsigned bit, unsigned bits_left,
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cmos_bit_op_location_t *where)
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{ unsigned max_bits;
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where->byte_index = bit >> 3;
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where->bit_offset = bit & 0x07;
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max_bits = 8 - where->bit_offset;
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return (bits_left > max_bits) ? max_bits : bits_left;
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}
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/****************************************************************************
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* cmos_read_bits
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*
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* Read a chunk of bits from a byte location within CMOS memory. Return the
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* value represented by the chunk of bits.
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****************************************************************************/
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static unsigned char cmos_read_bits (const cmos_bit_op_location_t *where,
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unsigned nr_bits)
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{ return (cmos_read_byte(where->byte_index) >> where->bit_offset) &
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((unsigned char) ((1 << nr_bits) - 1));
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}
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/****************************************************************************
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* cmos_write_bits
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*
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* Write a chunk of bits (the low order 'nr_bits' bits of 'value') to an area
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* within a particular byte of CMOS memory.
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****************************************************************************/
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static void cmos_write_bits (const cmos_bit_op_location_t *where,
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unsigned nr_bits, unsigned char value)
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{ unsigned char n, mask;
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if (nr_bits == 8)
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{ cmos_write_byte(where->byte_index, value);
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return;
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}
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n = cmos_read_byte(where->byte_index);
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mask = ((unsigned char) ((1 << nr_bits) - 1)) << where->bit_offset;
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n = (n & ~mask) + ((value << where->bit_offset) & mask);
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cmos_write_byte(where->byte_index, n);
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}
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