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Annotation of sys/arch/amd64/amd64/nvram.c, Revision 1.1.1.1

1.1       nbrk        1: /*     $OpenBSD: nvram.c,v 1.1 2007/08/02 16:40:27 deraadt Exp $ */
                      2:
                      3: /*
                      4:  * Copyright (c) 2004 Joshua Stein <jcs@openbsd.org>
                      5:  * All rights reserved.
                      6:  *
                      7:  * Redistribution and use in source and binary forms, with or without
                      8:  * modification, are permitted provided that the following conditions
                      9:  * are met:
                     10:  * 1. Redistributions of source code must retain the above copyright
                     11:  *    notice, this list of conditions and the following disclaimer.
                     12:  * 2. Redistributions in binary form must reproduce the above copyright
                     13:  *    notice, this list of conditions and the following disclaimer in the
                     14:  *    documentation and/or other materials provided with the distribution.
                     15:  *
                     16:  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
                     17:  * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
                     18:  * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
                     19:  * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
                     20:  * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
                     21:  * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
                     22:  * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
                     23:  * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
                     24:  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
                     25:  * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
                     26:  */
                     27:
                     28: #include <sys/param.h>
                     29: #include <sys/systm.h>
                     30: #include <sys/uio.h>
                     31: #include <sys/fcntl.h>
                     32: #include <sys/conf.h>
                     33:
                     34: #include <dev/ic/mc146818reg.h>
                     35: #include <amd64/isa/nvram.h>
                     36:
                     37: /* checksum is calculated over bytes 2 to 31 and stored in byte 32 */
                     38: #define NVRAM_CSUM_START       (MC_NVRAM_START + 2)
                     39: #define NVRAM_CSUM_END         (MC_NVRAM_START + 31)
                     40: #define NVRAM_CSUM_LOC         (MC_NVRAM_START + 32)
                     41:
                     42: #define NVRAM_SIZE             (128 - MC_NVRAM_START)
                     43:
                     44: /* #define NVRAM_DEBUG 1 */
                     45:
                     46: void nvramattach(int);
                     47:
                     48: int nvramopen(dev_t dev, int flag, int mode, struct proc *p);
                     49: int nvramclose(dev_t dev, int flag, int mode, struct proc *p);
                     50: int nvramread(dev_t dev, struct uio *uio, int flags);
                     51:
                     52: int nvram_csum_valid(void);
                     53: int nvram_get_byte(int byteno);
                     54:
                     55: static int nvram_initialized;
                     56:
                     57: void
                     58: nvramattach(int num)
                     59: {
                     60:        if (num > 1)
                     61:                return;
                     62:
                     63:        if (nvram_initialized || nvram_csum_valid()) {
                     64: #ifdef NVRAM_DEBUG
                     65:                printf("nvram: initialized\n");
                     66: #endif
                     67:                nvram_initialized = 1;
                     68:        } else
                     69:                printf("nvram: invalid checksum\n");
                     70: }
                     71:
                     72: int
                     73: nvramopen(dev_t dev, int flag, int mode, struct proc *p)
                     74: {
                     75:        /* TODO: re-calc checksum on every open? */
                     76:
                     77:        if ((minor(dev) != 0) || (!nvram_initialized))
                     78:                return (ENXIO);
                     79:
                     80:        if ((flag & FWRITE))
                     81:                return (EPERM);
                     82:
                     83:        return (0);
                     84: }
                     85:
                     86: int
                     87: nvramclose(dev_t dev, int flag, int mode, struct proc *p)
                     88: {
                     89:        return (0);
                     90: }
                     91:
                     92: int
                     93: nvramread(dev_t dev, struct uio *uio, int flags)
                     94: {
                     95:        u_char buf[NVRAM_SIZE];
                     96:        u_int pos = uio->uio_offset;
                     97:        u_char *tmp;
                     98:        int count = min(sizeof(buf), uio->uio_resid);
                     99:        int ret;
                    100:
                    101:        if (!nvram_initialized)
                    102:                return (ENXIO);
                    103:
                    104:        if (uio->uio_resid == 0)
                    105:                return (0);
                    106:
                    107: #ifdef NVRAM_DEBUG
                    108:        printf("attempting to read %d bytes at offset %d\n", count, pos);
                    109: #endif
                    110:
                    111:        for (tmp = buf; count-- > 0 && pos < NVRAM_SIZE; ++pos, ++tmp)
                    112:                *tmp = nvram_get_byte(pos);
                    113:
                    114: #ifdef NVRAM_DEBUG
                    115:        printf("nvramread read %d bytes (%s)\n", (tmp - buf), tmp);
                    116: #endif
                    117:
                    118:        ret = uiomove((caddr_t)buf, (tmp - buf), uio);
                    119:
                    120:        uio->uio_offset += uio->uio_resid;
                    121:
                    122:        return (ret);
                    123: }
                    124:
                    125: int
                    126: nvram_get_byte(int byteno)
                    127: {
                    128:        if (!nvram_initialized)
                    129:                return (ENXIO);
                    130:
                    131:        return (mc146818_read(NULL, byteno + MC_NVRAM_START) & 0xff);
                    132: }
                    133:
                    134: int
                    135: nvram_csum_valid()
                    136: {
                    137:        u_short csum = 0;
                    138:        u_short csumexpect;
                    139:        int nreg;
                    140:
                    141:        for (nreg = NVRAM_CSUM_START; nreg <= NVRAM_CSUM_END; nreg++)
                    142:                csum += mc146818_read(NULL, nreg);
                    143:
                    144:        csumexpect = mc146818_read(NULL, NVRAM_CSUM_LOC) << 8 |
                    145:            mc146818_read(NULL, NVRAM_CSUM_LOC + 1);
                    146:
                    147: #ifdef NVRAM_DEBUG
                    148:        printf("nvram: checksum is %x, expecting %x\n", (csum & 0xffff),
                    149:                csumexpect);
                    150: #endif
                    151:
                    152:        return ((csum & 0xffff) == csumexpect);
                    153: }