aboutsummaryrefslogtreecommitdiffstats
path: root/tools/firmware/hvmloader/util.c
blob: 80d822f75c4354cf9e7ebc4c0d999005f0e5d38e (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
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
665
666
667
668
669
670
671
672
673
674
675
676
677
678
679
680
681
682
683
684
685
686
687
688
689
690
691
692
693
694
695
696
697
698
699
700
701
702
703
704
705
706
707
708
709
710
711
712
713
714
715
716
717
718
719
720
721
722
723
724
725
726
727
728
729
730
731
732
733
734
735
736
737
738
739
740
741
742
743
744
745
746
747
748
749
750
751
752
753
754
755
756
757
758
759
760
761
762
763
764
765
766
767
768
769
770
771
772
773
774
775
776
777
778
779
780
781
782
783
784
785
786
787
788
789
790
791
792
793
794
795
796
797
798
799
800
801
802
803
804
805
806
807
808
809
810
811
812
813
814
815
816
817
818
819
820
821
822
823
824
825
826
827
828
829
830
831
832
833
834
835
836
837
838
839
/*
 * util.c: Helper library functions for HVMLoader.
 *
 * Leendert van Doorn, leendert@watson.ibm.com
 * Copyright (c) 2005, International Business Machines Corporation.
 *
 * This program is free software; you can redistribute it and/or modify it
 * under the terms and conditions of the GNU General Public License,
 * version 2, as published by the Free Software Foundation.
 *
 * This program is distributed in the hope 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 "util.h"
#include "config.h"
#include "hypercall.h"
#include "ctype.h"
#include <stdint.h>
#include <xen/xen.h>
#include <xen/memory.h>
#include <xen/sched.h>

void wrmsr(uint32_t idx, uint64_t v)
{
    asm volatile (
        "wrmsr"
        : : "c" (idx), "a" ((uint32_t)v), "d" ((uint32_t)(v>>32)) );
}

uint64_t rdmsr(uint32_t idx)
{
    uint32_t lo, hi;

    asm volatile (
        "rdmsr"
        : "=a" (lo), "=d" (hi) : "c" (idx) );

    return (lo | ((uint64_t)hi << 32));
}

void outb(uint16_t addr, uint8_t val)
{
    asm volatile ( "outb %%al, %%dx" : : "d" (addr), "a" (val) );
}

void outw(uint16_t addr, uint16_t val)
{
    asm volatile ( "outw %%ax, %%dx" : : "d" (addr), "a" (val) );
}

void outl(uint16_t addr, uint32_t val)
{
    asm volatile ( "outl %%eax, %%dx" : : "d" (addr), "a" (val) );
}

uint8_t inb(uint16_t addr)
{
    uint8_t val;
    asm volatile ( "inb %%dx,%%al" : "=a" (val) : "d" (addr) );
    return val;
}

uint16_t inw(uint16_t addr)
{
    uint16_t val;
    asm volatile ( "inw %%dx,%%ax" : "=a" (val) : "d" (addr) );
    return val;
}

uint32_t inl(uint16_t addr)
{
    uint32_t val;
    asm volatile ( "inl %%dx,%%eax" : "=a" (val) : "d" (addr) );
    return val;
}

uint8_t cmos_inb(uint8_t idx)
{
    outb(0x70, idx);
    return inb(0x71);
}

void cmos_outb(uint8_t idx, uint8_t val)
{
    outb(0x70, idx);
    outb(0x71, val);
}

char *itoa(char *a, unsigned int i)
{
    unsigned int _i = i, x = 0;

    do {
        x++;
        _i /= 10;
    } while ( _i != 0 );

    a += x;
    *a-- = '\0';

    do {
        *a-- = (i % 10) + '0';
        i /= 10;
    } while ( i != 0 );

    return a + 1;
}

int strcmp(const char *cs, const char *ct)
{
    signed char res;

    while ( ((res = *cs - *ct++) == 0) && (*cs++ != '\0') )
        continue;

    return res;
}

int strncmp(const char *s1, const char *s2, uint32_t n)
{
    uint32_t ctr;
    for (ctr = 0; ctr < n; ctr++)
        if (s1[ctr] != s2[ctr])
            return (int)(s1[ctr] - s2[ctr]);
    return 0;
}

void *memcpy(void *dest, const void *src, unsigned n)
{
    int t0, t1, t2;

    asm volatile (
        "cld\n"
        "rep; movsl\n"
        "testb $2,%b4\n"
        "je 1f\n"
        "movsw\n"
        "1: testb $1,%b4\n"
        "je 2f\n"
        "movsb\n"
        "2:"
        : "=&c" (t0), "=&D" (t1), "=&S" (t2)
        : "0" (n/4), "q" (n), "1" ((long) dest), "2" ((long) src)
        : "memory" );
    return dest;
}

void *memmove(void *dest, const void *src, unsigned n)
{
    if ( (unsigned long)dest > (unsigned long)src )
        while ( n-- != 0 )
            ((char *)dest)[n] = ((char *)src)[n];
    else
        memcpy(dest, src, n);
    return dest;
}

char *
strcpy(char *dest, const char *src)
{
    char *p = dest;
    while ( *src )
        *p++ = *src++;
    *p = 0;
    return dest;
}

char *
strncpy(char *dest, const char *src, unsigned n)
{
    int i = 0;
    char *p = dest;

    /* write non-NUL characters from src into dest until we run
       out of room in dest or encounter a NUL in src */
    while ( (i < n) && *src )
    {
        *p++ = *src++;
        i++;
    }

    /* pad remaining bytes of dest with NUL bytes */
    while ( i < n )
    {
        *p++ = 0;
        i++;
    }

    return dest;
}

unsigned
strlen(const char *s)
{
    int i = 0;
    while ( *s++ )
        i++;
    return i;
}

static inline int __digit(char c, int base)
{
    int d = -1;

    if ( (c >= '0') && (c <= '9') )
        d = c - '0';

    if ( (c >= 'A') && (c <= 'Z') )
        d = c - 'A' + 10;

    if ( (c >= 'a') && (c <= 'z') )
        d = c - 'a' + 10;

    if (d >= base)
        d = -1;

    return d;
}

long long
strtoll(const char *s, char **end, int base)
{
    long long v = 0;
    int sign = 1;

    while ( (*s != '\0') && isspace(*s) )
        s++;

    if ( *s == '\0' ) goto out;

    if ( *s == '-' ) {
        sign = -1;
        s++;
    } else {
        if ( *s == '+' )
            s++;
    }

    if ( *s == '\0' ) goto out;

    if ( *s == '0' ) {
        s++;
        if ( *s == '\0' ) goto out;

        if ( *s == 'x' ) {
            if ( base != 0 && base != 16) goto out;
            base = 16;
            s++;
        } else {
            if ( base != 0 && base != 8) goto out;
            base = 8;
        }
    } else {
        if (base != 0 && base != 10) goto out;
        base = 10;
    }

    while ( *s != '\0' ) {
        int d = __digit(*s, base);

        if ( d < 0 ) goto out;

        v = (v * base) + d;
        s++;
    }

out:
    if (end) *end = (char *)s;

    return sign * v;
}

void *
memset(void *s, int c, unsigned n)
{
    uint8_t b = (uint8_t) c;
    uint8_t *p = (uint8_t *)s;
    int i;
    for ( i = 0; i < n; i++ )
        *p++ = b;
    return s;
}

int
memcmp(const void *s1, const void *s2, unsigned n)
{
    unsigned i;
    uint8_t *p1 = (uint8_t *) s1;
    uint8_t *p2 = (uint8_t *) s2;

    for ( i = 0; i < n; i++ )
    {
        if ( p1[i] < p2[i] )
            return -1;
        else if ( p1[i] > p2[i] )
            return 1;
    }

    return 0;
}

void
cpuid(uint32_t idx, uint32_t *eax, uint32_t *ebx, uint32_t *ecx, uint32_t *edx)
{
    asm volatile (
        "cpuid"
        : "=a" (*eax), "=b" (*ebx), "=c" (*ecx), "=d" (*edx)
        : "0" (idx) );
}

static const char hex_digits[] = "0123456789abcdef";

/* Write a two-character hex representation of 'byte' to digits[].
   Pre-condition: sizeof(digits) >= 2 */
void
byte_to_hex(char *digits, uint8_t byte)
{
    digits[0] = hex_digits[byte >> 4];
    digits[1] = hex_digits[byte & 0x0f];
}

/* Convert an array of 16 unsigned bytes to a DCE/OSF formatted UUID
   string.

   Pre-condition: sizeof(dest) >= 37 */
void
uuid_to_string(char *dest, uint8_t *uuid)
{
    int i = 0;
    char *p = dest;

    for ( i = 0; i < 4; i++ )
    {
        byte_to_hex(p, uuid[i]);
        p += 2;
    }
    *p++ = '-';
    for ( i = 4; i < 6; i++ )
    {
        byte_to_hex(p, uuid[i]);
        p += 2;
    }
    *p++ = '-';
    for ( i = 6; i < 8; i++ )
    {
        byte_to_hex(p, uuid[i]);
        p += 2;
    }
    *p++ = '-';
    for ( i = 8; i < 10; i++ )
    {
        byte_to_hex(p, uuid[i]);
        p += 2;
    }
    *p++ = '-';
    for ( i = 10; i < 16; i++ )
    {
        byte_to_hex(p, uuid[i]);
        p += 2;
    }
    *p = '\0';
}

void mem_hole_populate_ram(xen_pfn_t mfn, uint32_t nr_mfns)
{
    static int over_allocated;
    struct xen_add_to_physmap xatp;
    struct xen_memory_reservation xmr;

    for ( ; nr_mfns-- != 0; mfn++ )
    {
        /* Try to allocate a brand new page in the reserved area. */
        if ( !over_allocated )
        {
            xmr.domid = DOMID_SELF;
            xmr.mem_flags = 0;
            xmr.extent_order = 0;
            xmr.nr_extents = 1;
            set_xen_guest_handle(xmr.extent_start, &mfn);
            if ( hypercall_memory_op(XENMEM_populate_physmap, &xmr) == 1 )
                continue;
            over_allocated = 1;
        }

        /* Otherwise, relocate a page from the ordinary RAM map. */
        if ( hvm_info->high_mem_pgend )
        {
            xatp.idx = --hvm_info->high_mem_pgend;
            if ( xatp.idx == (1ull << (32 - PAGE_SHIFT)) )
                hvm_info->high_mem_pgend = 0;
        }
        else
        {
            xatp.idx = --hvm_info->low_mem_pgend;
        }
        xatp.domid = DOMID_SELF;
        xatp.space = XENMAPSPACE_gmfn;
        xatp.gpfn  = mfn;
        if ( hypercall_memory_op(XENMEM_add_to_physmap, &xatp) != 0 )
            BUG();
    }
}

static uint32_t alloc_up = RESERVED_MEMORY_DYNAMIC_START - 1;
static uint32_t alloc_down = RESERVED_MEMORY_DYNAMIC_END;

xen_pfn_t mem_hole_alloc(uint32_t nr_mfns)
{
    alloc_down -= nr_mfns << PAGE_SHIFT;
    BUG_ON(alloc_up >= alloc_down);
    return alloc_down >> PAGE_SHIFT;
}

void *mem_alloc(uint32_t size, uint32_t align)
{
    uint32_t s, e;

    /* Align to at least 16 bytes. */
    if ( align < 16 )
        align = 16;

    s = (alloc_up + align) & ~(align - 1);
    e = s + size - 1;

    BUG_ON((e < s) || (e >= alloc_down));

    while ( (alloc_up >> PAGE_SHIFT) != (e >> PAGE_SHIFT) )
    {
        alloc_up += PAGE_SIZE;
        mem_hole_populate_ram(alloc_up >> PAGE_SHIFT, 1);
    }

    alloc_up = e;

    return (void *)(unsigned long)s;
}

void *scratch_alloc(uint32_t size, uint32_t align)
{
    uint32_t s, e;

    /* Align to at least 16 bytes. */
    if ( align < 16 )
        align = 16;

    s = (scratch_start + align - 1) & ~(align - 1);
    e = s + size - 1;

    BUG_ON(e < s);

    scratch_start = e;

    return (void *)(unsigned long)s;
}

uint32_t ioapic_read(uint32_t reg)
{
    *(volatile uint32_t *)(IOAPIC_BASE_ADDRESS + 0x00) = reg;
    return *(volatile uint32_t *)(IOAPIC_BASE_ADDRESS + 0x10);
}

void ioapic_write(uint32_t reg, uint32_t val)
{
    *(volatile uint32_t *)(IOAPIC_BASE_ADDRESS + 0x00) = reg;
    *(volatile uint32_t *)(IOAPIC_BASE_ADDRESS + 0x10) = val;
}

uint32_t lapic_read(uint32_t reg)
{
    return *(volatile uint32_t *)(LAPIC_BASE_ADDRESS + reg);
}

void lapic_write(uint32_t reg, uint32_t val)
{
    *(volatile uint32_t *)(LAPIC_BASE_ADDRESS + reg) = val;
}

#define PCI_CONF1_ADDRESS(bus, devfn, reg) \
    (0x80000000 | (bus << 16) | (devfn << 8) | (reg & ~3))

uint32_t pci_read(uint32_t devfn, uint32_t reg, uint32_t len)
{
    outl(0xcf8, PCI_CONF1_ADDRESS(0, devfn, reg));

    switch ( len )
    {
    case 1: return inb(0xcfc + (reg & 3));
    case 2: return inw(0xcfc + (reg & 2));
    }

    return inl(0xcfc);
}

void pci_write(uint32_t devfn, uint32_t reg, uint32_t len, uint32_t val)
{
    outl(0xcf8, PCI_CONF1_ADDRESS(0, devfn, reg));

    switch ( len )
    {
    case 1: outb(0xcfc + (reg & 3), val); break;
    case 2: outw(0xcfc + (reg & 2), val); break;
    case 4: outl(0xcfc,             val); break;
    }
}

static char *printnum(char *p, unsigned long num, unsigned base)
{
    unsigned long n;

    if ( (n = num/base) > 0 )
        p = printnum(p, n, base);
    *p++ = hex_digits[num % base];
    *p = '\0';
    return p;
}

static void _doprint(void (*emit)(void *, char), void *arg, const char *fmt, va_list ap)
{
    char *str, c;
    int lflag, zflag, nflag;
    char buffer[17];
    unsigned long value;
    int i, slen, pad;

    for ( ; *fmt != '\0'; fmt++ )
    {
        if ( *fmt != '%' )
        {
            emit(arg, *fmt);
            continue;
        }

        pad = zflag = nflag = lflag = 0;
        c = *++fmt;
        if ( (c == '-') || isdigit(c) )
        {
            if ( c == '-' )
            {
                nflag = 1;
                c = *++fmt;
            }
            zflag = c == '0';
            for ( pad = 0; isdigit(c); c = *++fmt )
                pad = (pad * 10) + c - '0';
        }
        if ( c == 'l' ) /* long extension */
        {
            lflag = 1;
            c = *++fmt;
        }
        if ( (c == 'd') || (c == 'u') || (c == 'o') ||
             (c == 'x') || (c == 'X') )
        {
            if ( lflag )
            {
                value = va_arg(ap, unsigned long);
                if ( (c == 'd') && ((long)value < 0) )
                {
                    value = -value;
                    emit(arg, '-');
                }
            }
            else
            {
                value = va_arg(ap, unsigned int);
                if ( (c == 'd') && ((int)value < 0) )
                {
                    value = -(int)value;
                    emit(arg, '-');
                }
            }
            str = buffer;
            printnum(str, value,
                     c == 'o' ? 8 : ((c == 'x') || (c == 'X') ? 16 : 10));
            slen = strlen(str);
            for ( i = pad - slen; i > 0; i-- )
                emit(arg, zflag ? '0' : ' ');
            while ( *str )
            {
                char ch = *str++;
                if ( (ch >= 'a') && (c == 'X') )
                    ch += 'A'-'a';
                emit(arg, ch);
            }
        }
        else if ( c == 's' )
        {
            str = va_arg(ap, char *);
            slen = strlen(str);
            if ( nflag == 0 )
                for ( i = pad - slen; i > 0; i-- )
                    emit(arg, ' ');
            while ( *str )
                emit(arg, *str++);
            if ( nflag )
                for ( i = pad - slen; i > 0; i-- )
                    emit(arg, ' ');
        }
        else if ( c == 'c' )
        {
            emit(arg, va_arg(ap, int));
        }
        else
        {
            emit(arg, *fmt);
        }
    }
}

static void putchar(char c)
{
    outb(0xe9, c);
}

static void __put(void *arg, char c)
{
    putchar(c);
}

int printf(const char *fmt, ...)
{
    va_list ap;

    va_start(ap, fmt);
    _doprint(__put, NULL, fmt, ap);
    va_end(ap);

    return 0;
}

int vprintf(const char *fmt, va_list ap)
{
    _doprint(__put, NULL, fmt, ap);
    return 0;
}

struct __copy_context {
    char *ptr;
    size_t emitted;
    size_t remaining;
};

static void __copy(void *arg, char c)
{
    struct __copy_context *ctxt = arg;

    ctxt->emitted++;

    if (ctxt->remaining == 0)
        return;
    
    *(ctxt->ptr++) = c;
    --ctxt->remaining;
}

int snprintf(char *buf, size_t size, const char *fmt, ...)
{
    va_list ap;
    struct __copy_context ctxt;

    ctxt.ptr = buf;
    ctxt.emitted = 0;
    ctxt.remaining = size;

    va_start(ap, fmt);
    _doprint(__copy, &ctxt, fmt, ap);
    va_end(ap);

    if (ctxt.remaining != 0)
        *ctxt.ptr = '\0';

    return ctxt.emitted;
}

static void __attribute__((noreturn)) crash(void)
{
    struct sched_shutdown shutdown = { .reason = SHUTDOWN_crash };
    printf("*** HVMLoader crashed.\n");
    hypercall_sched_op(SCHEDOP_shutdown, &shutdown);
    printf("*** Failed to crash. Halting.\n");
    for ( ; ; )
        asm volatile ( "hlt" );
}

void __assert_failed(char *assertion, char *file, int line)
{
    printf("*** HVMLoader assertion '%s' failed at %s:%d\n",
           assertion, file, line);
    crash();
}

void __bug(char *file, int line)
{
    printf("*** HVMLoader bug at %s:%d\n", file, line);
    crash();
}

static void validate_hvm_info(struct hvm_info_table *t)
{
    uint8_t *ptr = (uint8_t *)t;
    uint8_t sum = 0;
    int i;

    if ( strncmp(t->signature, "HVM INFO", 8) )
    {
        printf("Bad hvm info signature\n");
        BUG();
    }

    if ( t->length < sizeof(struct hvm_info_table) )
    {
        printf("Bad hvm info length\n");
        BUG();
    }

    for ( i = 0; i < t->length; i++ )
        sum += ptr[i];

    if ( sum != 0 )
    {
        printf("Bad hvm info checksum\n");
        BUG();
    }
}

struct hvm_info_table *get_hvm_info_table(void)
{
    static struct hvm_info_table *table;
    struct hvm_info_table *t;

    if ( table != NULL )
        return table;

    t = (struct hvm_info_table *)HVM_INFO_PADDR;

    validate_hvm_info(t);

    table = t;

    return table;
}

struct shared_info *get_shared_info(void) 
{
    static struct shared_info *shared_info = NULL;
    struct xen_add_to_physmap xatp;

    if ( shared_info != NULL )
        return shared_info;

    xatp.domid = DOMID_SELF;
    xatp.space = XENMAPSPACE_shared_info;
    xatp.idx   = 0;
    xatp.gpfn  = mem_hole_alloc(1);
    shared_info = (struct shared_info *)(xatp.gpfn << PAGE_SHIFT);
    if ( hypercall_memory_op(XENMEM_add_to_physmap, &xatp) != 0 )
        BUG();

    return shared_info;
}

uint16_t get_cpu_mhz(void)
{
    struct shared_info *shared_info = get_shared_info();
    struct vcpu_time_info *info = &shared_info->vcpu_info[0].time;
    uint64_t cpu_khz;
    uint32_t tsc_to_nsec_mul, version;
    int8_t tsc_shift;

    static uint16_t cpu_mhz;
    if ( cpu_mhz != 0 )
        return cpu_mhz;

    /* Get a consistent snapshot of scale factor (multiplier and shift). */
    do {
        version = info->version;
        rmb();
        tsc_to_nsec_mul = info->tsc_to_system_mul;
        tsc_shift       = info->tsc_shift;
        rmb();
    } while ((version & 1) | (version ^ info->version));

    /* Compute CPU speed in kHz. */
    cpu_khz = 1000000ull << 32;
    do_div(cpu_khz, tsc_to_nsec_mul);
    if ( tsc_shift < 0 )
        cpu_khz = cpu_khz << -tsc_shift;
    else
        cpu_khz = cpu_khz >> tsc_shift;

    cpu_mhz = (uint16_t)(((uint32_t)cpu_khz + 500) / 1000);
    return cpu_mhz;
}

int uart_exists(uint16_t uart_base)
{
    uint16_t ier = uart_base + 1;
    uint8_t a, b, c;

    a = inb(ier);
    outb(ier, 0);
    b = inb(ier);
    outb(ier, 0xf);
    c = inb(ier);
    outb(ier, a);

    return ((b == 0) && (c == 0xf));
}

int lpt_exists(uint16_t lpt_base)
{
    /* Idea taken from linux-2.6.31.5:parport_pc.c */
    uint16_t control = lpt_base + 2;
    outb(control, 0xc);
    return ((inb(control) & 0xf) == 0xc);
}

int hpet_exists(unsigned long hpet_base)
{
    uint32_t hpet_id = *(uint32_t *)hpet_base;
    return ((hpet_id >> 16) == 0x8086);
}

/*
 * Local variables:
 * mode: C
 * c-file-style: "BSD"
 * c-basic-offset: 4
 * tab-width: 4
 * indent-tabs-mode: nil
 * End:
 */