The Design and Implementation of the FreeBSD Operating System, Second Edition
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FreeBSD/Linux Kernel Cross Reference
sys/i386/i386/bios.c

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    1 /*-
    2  * Copyright (c) 1997 Michael Smith
    3  * Copyright (c) 1998 Jonathan Lemon
    4  * All rights reserved.
    5  *
    6  * Redistribution and use in source and binary forms, with or without
    7  * modification, are permitted provided that the following conditions
    8  * are met:
    9  * 1. Redistributions of source code must retain the above copyright
   10  *    notice, this list of conditions and the following disclaimer.
   11  * 2. Redistributions in binary form must reproduce the above copyright
   12  *    notice, this list of conditions and the following disclaimer in the
   13  *    documentation and/or other materials provided with the distribution.
   14  *
   15  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
   16  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
   17  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
   18  * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
   19  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
   20  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
   21  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
   22  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
   23  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
   24  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
   25  * SUCH DAMAGE.
   26  */
   27 
   28 #include <sys/cdefs.h>
   29 __FBSDID("$FreeBSD$");
   30 
   31 /*
   32  * Code for dealing with the BIOS in x86 PC systems.
   33  */
   34 
   35 #include "opt_isa.h"
   36 
   37 #include <sys/param.h>
   38 #include <sys/systm.h>
   39 #include <sys/kernel.h>
   40 #include <sys/malloc.h>
   41 #include <sys/module.h>
   42 #include <sys/bus.h>
   43 #include <sys/pcpu.h>
   44 #include <vm/vm.h>
   45 #include <vm/pmap.h>
   46 #include <machine/md_var.h>
   47 #include <machine/segments.h>
   48 #include <machine/stdarg.h>
   49 #include <machine/vmparam.h>
   50 #include <machine/pc/bios.h>
   51 #ifdef DEV_ISA
   52 #include <isa/isavar.h>
   53 #include <isa/pnpreg.h>
   54 #include <isa/pnpvar.h>
   55 #endif
   56 
   57 #define BIOS_START      0xe0000
   58 #define BIOS_SIZE       0x20000
   59 
   60 /* exported lookup results */
   61 struct bios32_SDentry           PCIbios;
   62 
   63 static struct PnPBIOS_table     *PnPBIOStable;
   64 
   65 static u_int                    bios32_SDCI;
   66 
   67 /* start fairly early */
   68 static void                     bios32_init(void *junk);
   69 SYSINIT(bios32, SI_SUB_CPU, SI_ORDER_ANY, bios32_init, NULL);
   70 
   71 /*
   72  * bios32_init
   73  *
   74  * Locate various bios32 entities.
   75  */
   76 static void
   77 bios32_init(void *junk)
   78 {
   79     u_long                      sigaddr;
   80     struct bios32_SDheader      *sdh;
   81     struct PnPBIOS_table        *pt;
   82     u_int8_t                    ck, *cv;
   83     int                         i;
   84     char                        *p;
   85     
   86     /*
   87      * BIOS32 Service Directory, PCI BIOS
   88      */
   89     
   90     /* look for the signature */
   91     if ((sigaddr = bios_sigsearch(0, "_32_", 4, 16, 0)) != 0) {
   92 
   93         /* get a virtual pointer to the structure */
   94         sdh = (struct bios32_SDheader *)(uintptr_t)BIOS_PADDRTOVADDR(sigaddr);
   95         for (cv = (u_int8_t *)sdh, ck = 0, i = 0; i < (sdh->len * 16); i++) {
   96             ck += cv[i];
   97         }
   98         /* If checksum is OK, enable use of the entrypoint */
   99         if ((ck == 0) && (BIOS_START <= sdh->entry ) &&
  100             (sdh->entry < (BIOS_START + BIOS_SIZE))) {
  101             bios32_SDCI = BIOS_PADDRTOVADDR(sdh->entry);
  102             if (bootverbose) {
  103                 printf("bios32: Found BIOS32 Service Directory header at %p\n", sdh);
  104                 printf("bios32: Entry = 0x%x (%x)  Rev = %d  Len = %d\n", 
  105                        sdh->entry, bios32_SDCI, sdh->revision, sdh->len);
  106             }
  107 
  108             /* Allow user override of PCI BIOS search */
  109             if (((p = getenv("machdep.bios.pci")) == NULL) || strcmp(p, "disable")) {
  110 
  111                 /* See if there's a PCI BIOS entrypoint here */
  112                 PCIbios.ident.id = 0x49435024;  /* PCI systems should have this */
  113                 if (!bios32_SDlookup(&PCIbios) && bootverbose)
  114                     printf("pcibios: PCI BIOS entry at 0x%x+0x%x\n", PCIbios.base, PCIbios.entry);
  115             }
  116             if (p != NULL)
  117                     freeenv(p);
  118         } else {
  119             printf("bios32: Bad BIOS32 Service Directory\n");
  120         }
  121     }
  122 
  123     /*
  124      * PnP BIOS
  125      *
  126      * Allow user override of PnP BIOS search
  127      */
  128     if ((((p = getenv("machdep.bios.pnp")) == NULL) || strcmp(p, "disable")) &&
  129         ((sigaddr = bios_sigsearch(0, "$PnP", 4, 16, 0)) != 0)) {
  130 
  131         /* get a virtual pointer to the structure */
  132         pt = (struct PnPBIOS_table *)(uintptr_t)BIOS_PADDRTOVADDR(sigaddr);
  133         for (cv = (u_int8_t *)pt, ck = 0, i = 0; i < pt->len; i++) {
  134             ck += cv[i];
  135         }
  136         /* If checksum is OK, enable use of the entrypoint */
  137         if (ck == 0) {
  138             PnPBIOStable = pt;
  139             if (bootverbose) {
  140                 printf("pnpbios: Found PnP BIOS data at %p\n", pt);
  141                 printf("pnpbios: Entry = %x:%x  Rev = %d.%d\n", 
  142                        pt->pmentrybase, pt->pmentryoffset, pt->version >> 4, pt->version & 0xf);
  143                 if ((pt->control & 0x3) == 0x01)
  144                     printf("pnpbios: Event flag at %x\n", pt->evflagaddr);
  145                 if (pt->oemdevid != 0)
  146                     printf("pnpbios: OEM ID %x\n", pt->oemdevid);
  147                 
  148             }
  149         } else {
  150             printf("pnpbios: Bad PnP BIOS data checksum\n");
  151         }
  152     }
  153     if (p != NULL)
  154             freeenv(p);
  155     if (bootverbose) {
  156             /* look for other know signatures */
  157             printf("Other BIOS signatures found:\n");
  158     }
  159 }
  160 
  161 /*
  162  * bios32_SDlookup
  163  *
  164  * Query the BIOS32 Service Directory for the service named in (ent),
  165  * returns nonzero if the lookup fails.  The caller must fill in
  166  * (ent->ident), the remainder are populated on a successful lookup.
  167  */
  168 int
  169 bios32_SDlookup(struct bios32_SDentry *ent)
  170 {
  171     struct bios_regs args;
  172 
  173     if (bios32_SDCI == 0)
  174         return (1);
  175 
  176     args.eax = ent->ident.id;           /* set up arguments */
  177     args.ebx = args.ecx = args.edx = 0;
  178     bios32(&args, bios32_SDCI, GSEL(GCODE_SEL, SEL_KPL));
  179     if ((args.eax & 0xff) == 0) {       /* success? */
  180         ent->base = args.ebx;
  181         ent->len = args.ecx;
  182         ent->entry = args.edx;
  183         ent->ventry = BIOS_PADDRTOVADDR(ent->base + ent->entry);
  184         return (0);                     /* all OK */
  185     }
  186     return (1);                         /* failed */
  187 }
  188 
  189 
  190 /*
  191  * bios_sigsearch
  192  *
  193  * Search some or all of the BIOS region for a signature string.
  194  *
  195  * (start)      Optional offset returned from this function 
  196  *              (for searching for multiple matches), or NULL
  197  *              to start the search from the base of the BIOS.
  198  *              Note that this will be a _physical_ address in
  199  *              the range 0xe0000 - 0xfffff.
  200  * (sig)        is a pointer to the byte(s) of the signature.
  201  * (siglen)     number of bytes in the signature.
  202  * (paralen)    signature paragraph (alignment) size.
  203  * (sigofs)     offset of the signature within the paragraph.
  204  *
  205  * Returns the _physical_ address of the found signature, 0 if the
  206  * signature was not found.
  207  */
  208 
  209 u_int32_t
  210 bios_sigsearch(u_int32_t start, u_char *sig, int siglen, int paralen, int sigofs)
  211 {
  212     u_char      *sp, *end;
  213     
  214     /* compute the starting address */
  215     if ((start >= BIOS_START) && (start <= (BIOS_START + BIOS_SIZE))) {
  216         sp = (char *)BIOS_PADDRTOVADDR(start);
  217     } else if (start == 0) {
  218         sp = (char *)BIOS_PADDRTOVADDR(BIOS_START);
  219     } else {
  220         return 0;                               /* bogus start address */
  221     }
  222 
  223     /* compute the end address */
  224     end = (u_char *)BIOS_PADDRTOVADDR(BIOS_START + BIOS_SIZE);
  225 
  226     /* loop searching */
  227     while ((sp + sigofs + siglen) < end) {
  228         
  229         /* compare here */
  230         if (!bcmp(sp + sigofs, sig, siglen)) {
  231             /* convert back to physical address */
  232             return((u_int32_t)BIOS_VADDRTOPADDR(sp));
  233         }
  234         sp += paralen;
  235     }
  236     return(0);
  237 }
  238 
  239 /*
  240  * do not staticize, used by bioscall.s
  241  */
  242 union {
  243     struct {
  244         u_short offset;
  245         u_short segment;
  246     } vec16;
  247     struct {
  248         u_int   offset;
  249         u_short segment;
  250     } vec32;
  251 } bioscall_vector;                      /* bios jump vector */
  252 
  253 void
  254 set_bios_selectors(struct bios_segments *seg, int flags)
  255 {
  256     struct soft_segment_descriptor ssd = {
  257         0,                      /* segment base address (overwritten) */
  258         0,                      /* length (overwritten) */
  259         SDT_MEMERA,             /* segment type (overwritten) */
  260         0,                      /* priority level */
  261         1,                      /* descriptor present */
  262         0, 0,
  263         1,                      /* descriptor size (overwritten) */
  264         0                       /* granularity == byte units */
  265     };
  266     union descriptor *p_gdt;
  267 
  268 #ifdef SMP
  269     p_gdt = &gdt[PCPU_GET(cpuid) * NGDT];
  270 #else
  271     p_gdt = gdt;
  272 #endif
  273         
  274     ssd.ssd_base = seg->code32.base;
  275     ssd.ssd_limit = seg->code32.limit;
  276     ssdtosd(&ssd, &p_gdt[GBIOSCODE32_SEL].sd);
  277 
  278     ssd.ssd_def32 = 0;
  279     if (flags & BIOSCODE_FLAG) {
  280         ssd.ssd_base = seg->code16.base;
  281         ssd.ssd_limit = seg->code16.limit;
  282         ssdtosd(&ssd, &p_gdt[GBIOSCODE16_SEL].sd);
  283     }
  284 
  285     ssd.ssd_type = SDT_MEMRWA;
  286     if (flags & BIOSDATA_FLAG) {
  287         ssd.ssd_base = seg->data.base;
  288         ssd.ssd_limit = seg->data.limit;
  289         ssdtosd(&ssd, &p_gdt[GBIOSDATA_SEL].sd);
  290     }
  291 
  292     if (flags & BIOSUTIL_FLAG) {
  293         ssd.ssd_base = seg->util.base;
  294         ssd.ssd_limit = seg->util.limit;
  295         ssdtosd(&ssd, &p_gdt[GBIOSUTIL_SEL].sd);
  296     }
  297 
  298     if (flags & BIOSARGS_FLAG) {
  299         ssd.ssd_base = seg->args.base;
  300         ssd.ssd_limit = seg->args.limit;
  301         ssdtosd(&ssd, &p_gdt[GBIOSARGS_SEL].sd);
  302     }
  303 }
  304 
  305 extern int vm86pa;
  306 extern void bios16_jmp(void);
  307 
  308 /*
  309  * this routine is really greedy with selectors, and uses 5:
  310  *
  311  * 32-bit code selector:        to return to kernel
  312  * 16-bit code selector:        for running code
  313  *        data selector:        for 16-bit data
  314  *        util selector:        extra utility selector
  315  *        args selector:        to handle pointers
  316  *
  317  * the util selector is set from the util16 entry in bios16_args, if a
  318  * "U" specifier is seen.
  319  *
  320  * See <machine/pc/bios.h> for description of format specifiers
  321  */
  322 int
  323 bios16(struct bios_args *args, char *fmt, ...)
  324 {
  325     char        *p, *stack, *stack_top;
  326     va_list     ap;
  327     int         flags = BIOSCODE_FLAG | BIOSDATA_FLAG;
  328     u_int       i, arg_start, arg_end;
  329     pt_entry_t  *pte;
  330     pd_entry_t  *ptd;
  331 
  332     arg_start = 0xffffffff;
  333     arg_end = 0;
  334 
  335     /*
  336      * Some BIOS entrypoints attempt to copy the largest-case
  337      * argument frame (in order to generalise handling for 
  338      * different entry types).  If our argument frame is 
  339      * smaller than this, the BIOS will reach off the top of
  340      * our constructed stack segment.  Pad the top of the stack
  341      * with some garbage to avoid this.
  342      */
  343     stack = (caddr_t)PAGE_SIZE - 32;
  344 
  345     va_start(ap, fmt);
  346     for (p = fmt; p && *p; p++) {
  347         switch (*p) {
  348         case 'p':                       /* 32-bit pointer */
  349             i = va_arg(ap, u_int);
  350             arg_start = min(arg_start, i);
  351             arg_end = max(arg_end, i);
  352             flags |= BIOSARGS_FLAG;
  353             stack -= 4;
  354             break;
  355 
  356         case 'i':                       /* 32-bit integer */
  357             i = va_arg(ap, u_int);
  358             stack -= 4;
  359             break;
  360 
  361         case 'U':                       /* 16-bit selector */
  362             flags |= BIOSUTIL_FLAG;
  363             /* FALLTHROUGH */
  364         case 'D':                       /* 16-bit selector */
  365         case 'C':                       /* 16-bit selector */
  366             stack -= 2;
  367             break;
  368             
  369         case 's':                       /* 16-bit integer passed as an int */
  370             i = va_arg(ap, int);
  371             stack -= 2;
  372             break;
  373 
  374         default:
  375             return (EINVAL);
  376         }
  377     }
  378 
  379     if (flags & BIOSARGS_FLAG) {
  380         if (arg_end - arg_start > ctob(16))
  381             return (EACCES);
  382         args->seg.args.base = arg_start;
  383         args->seg.args.limit = 0xffff;
  384     }
  385 
  386     args->seg.code32.base = (u_int)&bios16_jmp & PG_FRAME;
  387     args->seg.code32.limit = 0xffff;    
  388 
  389     ptd = (pd_entry_t *)rcr3();
  390 #ifdef PAE
  391     if (ptd == IdlePDPT)
  392 #else
  393     if (ptd == IdlePTD)
  394 #endif
  395     {
  396         /*
  397          * no page table, so create one and install it.
  398          */
  399         pte = (pt_entry_t *)malloc(PAGE_SIZE, M_TEMP, M_WAITOK);
  400         ptd = (pd_entry_t *)((u_int)IdlePTD + KERNBASE);
  401         *pte = (vm86pa - PAGE_SIZE) | PG_RW | PG_V;
  402         *ptd = vtophys(pte) | PG_RW | PG_V;
  403     } else {
  404         /*
  405          * this is a user-level page table 
  406          */
  407         pte = PTmap;
  408         *pte = (vm86pa - PAGE_SIZE) | PG_RW | PG_V;
  409     }
  410     pmap_invalidate_all(kernel_pmap);   /* XXX insurance for now */
  411 
  412     stack_top = stack;
  413     va_start(ap, fmt);
  414     for (p = fmt; p && *p; p++) {
  415         switch (*p) {
  416         case 'p':                       /* 32-bit pointer */
  417             i = va_arg(ap, u_int);
  418             *(u_int *)stack = (i - arg_start) |
  419                 (GSEL(GBIOSARGS_SEL, SEL_KPL) << 16);
  420             stack += 4;
  421             break;
  422 
  423         case 'i':                       /* 32-bit integer */
  424             i = va_arg(ap, u_int);
  425             *(u_int *)stack = i;
  426             stack += 4;
  427             break;
  428 
  429         case 'U':                       /* 16-bit selector */
  430             *(u_short *)stack = GSEL(GBIOSUTIL_SEL, SEL_KPL);
  431             stack += 2;
  432             break;
  433 
  434         case 'D':                       /* 16-bit selector */
  435             *(u_short *)stack = GSEL(GBIOSDATA_SEL, SEL_KPL);
  436             stack += 2;
  437             break;
  438 
  439         case 'C':                       /* 16-bit selector */
  440             *(u_short *)stack = GSEL(GBIOSCODE16_SEL, SEL_KPL);
  441             stack += 2;
  442             break;
  443 
  444         case 's':                       /* 16-bit integer passed as an int */
  445             i = va_arg(ap, int);
  446             *(u_short *)stack = i;
  447             stack += 2;
  448             break;
  449 
  450         default:
  451             return (EINVAL);
  452         }
  453     }
  454 
  455     set_bios_selectors(&args->seg, flags);
  456     bioscall_vector.vec16.offset = (u_short)args->entry;
  457     bioscall_vector.vec16.segment = GSEL(GBIOSCODE16_SEL, SEL_KPL);
  458 
  459     i = bios16_call(&args->r, stack_top);
  460 
  461     if (pte == PTmap) {
  462         *pte = 0;                       /* remove entry */
  463         /*
  464          * XXX only needs to be invlpg(0) but that doesn't work on the 386 
  465          */
  466         pmap_invalidate_all(kernel_pmap);
  467     } else {
  468         *ptd = 0;                       /* remove page table */
  469         /*
  470          * XXX only needs to be invlpg(0) but that doesn't work on the 386 
  471          */
  472         pmap_invalidate_all(kernel_pmap);
  473         free(pte, M_TEMP);              /* ... and free it */
  474     }
  475     return (i);
  476 }
  477 
  478 int bios_oem_strings(struct bios_oem *oem, u_char *buffer, size_t maxlen)
  479 {
  480         size_t idx = 0;
  481         struct bios_oem_signature *sig;
  482         u_int from, to;
  483         u_char c, *s, *se, *str, *bios_str;
  484         size_t i, off, len, tot;
  485 
  486         if ( !oem || !buffer || maxlen<2 )
  487                 return(-1);
  488 
  489         sig = oem->signature;
  490         if (!sig)
  491                 return(-2);
  492 
  493         from = oem->range.from;
  494         to = oem->range.to;
  495         if ( (to<=from) || (from<BIOS_START) || (to>(BIOS_START+BIOS_SIZE)) )
  496                 return(-3);
  497 
  498         while (sig->anchor != NULL) {
  499                 str = sig->anchor;
  500                 len = strlen(str);
  501                 off = sig->offset;
  502                 tot = sig->totlen;
  503                 /* make sure offset doesn't go beyond bios area */
  504                 if ( (to+off)>(BIOS_START+BIOS_SIZE) ||
  505                                         ((from+off)<BIOS_START) ) {
  506                         printf("sys/i386/i386/bios.c: sig '%s' "
  507                                 "from 0x%0x to 0x%0x offset %d "
  508                                 "out of BIOS bounds 0x%0x - 0x%0x\n",
  509                                 str, from, to, off,
  510                                 BIOS_START, BIOS_START+BIOS_SIZE);
  511                         return(-4);
  512                 }
  513                 /* make sure we don't overrun return buffer */
  514                 if (idx + tot > maxlen - 1) {
  515                         printf("sys/i386/i386/bios.c: sig '%s' "
  516                                 "idx %d + tot %d = %d > maxlen-1 %d\n",
  517                                 str, idx, tot, idx+tot, maxlen-1);
  518                         return(-5);
  519                 }
  520                 bios_str = NULL;
  521                 s = (u_char *)BIOS_PADDRTOVADDR(from);
  522                 se = (u_char *)BIOS_PADDRTOVADDR(to-len);
  523                 for (; s<se; s++) {
  524                         if (!memcmp(str, s, len)) {
  525                                 bios_str = s;
  526                                 break;
  527                         }
  528                 }
  529                 /*
  530                 *  store pretty version of totlen bytes of bios string with
  531                 *  given offset; 0x20 - 0x7E are printable; uniquify spaces
  532                 */
  533                 if (bios_str) {
  534                         for (i=0; i<tot; i++) {
  535                                 c = bios_str[i+off];
  536                                 if ( (c < 0x20) || (c > 0x7E) )
  537                                         c = ' ';
  538                                 if (idx == 0) {
  539                                         if (c != ' ')
  540                                                 buffer[idx++] = c;
  541                                 } else if ( (c != ' ') ||
  542                                         ((c == ' ') && (buffer[idx-1] != ' ')) )
  543                                                 buffer[idx++] = c;
  544                         }
  545                 }
  546                 sig++;
  547         }
  548         /* remove a final trailing space */
  549         if ( (idx > 1) && (buffer[idx-1] == ' ') )
  550                 idx--;
  551         buffer[idx] = '\0';
  552         return (idx);
  553 }
  554 
  555 #ifdef DEV_ISA
  556 /*
  557  * PnP BIOS interface; enumerate devices only known to the system
  558  * BIOS and save information about them for later use.
  559  */
  560 
  561 struct pnp_sysdev 
  562 {
  563     u_int16_t   size;
  564     u_int8_t    handle;
  565     u_int32_t   devid;
  566     u_int8_t    type[3];
  567     u_int16_t   attrib;
  568 #define PNPATTR_NODISABLE       (1<<0)  /* can't be disabled */
  569 #define PNPATTR_NOCONFIG        (1<<1)  /* can't be configured */
  570 #define PNPATTR_OUTPUT          (1<<2)  /* can be primary output */
  571 #define PNPATTR_INPUT           (1<<3)  /* can be primary input */
  572 #define PNPATTR_BOOTABLE        (1<<4)  /* can be booted from */
  573 #define PNPATTR_DOCK            (1<<5)  /* is a docking station */
  574 #define PNPATTR_REMOVEABLE      (1<<6)  /* device is removeable */
  575 #define PNPATTR_CONFIG_STATIC   (0)
  576 #define PNPATTR_CONFIG_DYNAMIC  (1)
  577 #define PNPATTR_CONFIG_DYNONLY  (3)
  578 #define PNPATTR_CONFIG(a)       (((a) >> 7) & 0x3)
  579     /* device-specific data comes here */
  580     u_int8_t    devdata[0];
  581 } __packed;
  582 
  583 /* We have to cluster arguments within a 64k range for the bios16 call */
  584 struct pnp_sysdevargs
  585 {
  586     u_int16_t   next;
  587     struct pnp_sysdev node;
  588 };
  589 
  590 /*
  591  * This function is called after the bus has assigned resource
  592  * locations for a logical device.
  593  */
  594 static void
  595 pnpbios_set_config(void *arg, struct isa_config *config, int enable)
  596 {
  597 }
  598 
  599 /*
  600  * Quiz the PnP BIOS, build a list of PNP IDs and resource data.
  601  */
  602 static void
  603 pnpbios_identify(driver_t *driver, device_t parent)
  604 {
  605     struct PnPBIOS_table        *pt = PnPBIOStable;
  606     struct bios_args            args;
  607     struct pnp_sysdev           *pd;
  608     struct pnp_sysdevargs       *pda;
  609     u_int16_t                   ndevs, bigdev;
  610     int                         error, currdev;
  611     u_int8_t                    *devnodebuf, tag;
  612     u_int32_t                   *devid, *compid;
  613     int                         idx, left;
  614     device_t                    dev;
  615         
  616     /* no PnP BIOS information */
  617     if (pt == NULL)
  618         return;
  619 
  620     /* Check to see if ACPI is already active. */
  621     dev = devclass_get_device(devclass_find("acpi"), 0);
  622     if (dev != NULL && device_is_attached(dev)) 
  623         return;
  624 
  625     /* get count of PnP devices */
  626     bzero(&args, sizeof(args));
  627     args.seg.code16.base = BIOS_PADDRTOVADDR(pt->pmentrybase);
  628     args.seg.code16.limit = 0xffff;             /* XXX ? */
  629     args.seg.data.base = BIOS_PADDRTOVADDR(pt->pmdataseg);
  630     args.seg.data.limit = 0xffff;
  631     args.entry = pt->pmentryoffset;
  632     
  633     if ((error = bios16(&args, PNP_COUNT_DEVNODES, &ndevs, &bigdev)) || (args.r.eax & 0xff)) {
  634         printf("pnpbios: error %d/%x getting device count/size limit\n", error, args.r.eax);
  635         return;
  636     }
  637     ndevs &= 0xff;                              /* clear high byte garbage */
  638     if (bootverbose)
  639         printf("pnpbios: %d devices, largest %d bytes\n", ndevs, bigdev);
  640 
  641     devnodebuf = malloc(bigdev + (sizeof(struct pnp_sysdevargs) - sizeof(struct pnp_sysdev)),
  642                         M_DEVBUF, M_NOWAIT);
  643     if (devnodebuf == NULL) {
  644         printf("pnpbios: cannot allocate memory, bailing\n");
  645         return;
  646     }
  647     pda = (struct pnp_sysdevargs *)devnodebuf;
  648     pd = &pda->node;
  649 
  650     for (currdev = 0, left = ndevs; (currdev != 0xff) && (left > 0); left--) {
  651 
  652         bzero(pd, bigdev);
  653         pda->next = currdev;
  654         /* get current configuration */
  655         if ((error = bios16(&args, PNP_GET_DEVNODE, &pda->next, &pda->node, 1))) {
  656             printf("pnpbios: error %d making BIOS16 call\n", error);
  657             break;
  658         }
  659         if ((error = (args.r.eax & 0xff))) {
  660             if (bootverbose)
  661                 printf("pnpbios: %s 0x%x fetching node %d\n", error & 0x80 ? "error" : "warning", error, currdev);
  662             if (error & 0x80) 
  663                 break;
  664         }
  665         currdev = pda->next;
  666         if (pd->size < sizeof(struct pnp_sysdev)) {
  667             printf("pnpbios: bogus system node data, aborting scan\n");
  668             break;
  669         }
  670 
  671         /*
  672          * Ignore PICs so that we don't have to worry about the PICs
  673          * claiming IRQs to prevent their use.  The PIC drivers
  674          * already ensure that invalid IRQs are not used.
  675          */
  676         if (!strcmp(pnp_eisaformat(pd->devid), "PNP0000"))      /* ISA PIC */
  677             continue;
  678         if (!strcmp(pnp_eisaformat(pd->devid), "PNP0003"))      /* APIC */
  679             continue;
  680         
  681         /* Add the device and parse its resources */
  682         dev = BUS_ADD_CHILD(parent, ISA_ORDER_PNPBIOS, NULL, -1);
  683         isa_set_vendorid(dev, pd->devid);
  684         isa_set_logicalid(dev, pd->devid);
  685         /*
  686          * It appears that some PnP BIOS doesn't allow us to re-enable
  687          * the embedded system device once it is disabled.  We shall
  688          * mark all system device nodes as "cannot be disabled", regardless
  689          * of actual settings in the device attribute byte.
  690          * XXX
  691         isa_set_configattr(dev, 
  692             ((pd->attrib & PNPATTR_NODISABLE) ?  0 : ISACFGATTR_CANDISABLE) |
  693             ((!(pd->attrib & PNPATTR_NOCONFIG) && 
  694                 PNPATTR_CONFIG(pd->attrib) != PNPATTR_CONFIG_STATIC)
  695                 ? ISACFGATTR_DYNAMIC : 0));
  696          */
  697         isa_set_configattr(dev, 
  698             (!(pd->attrib & PNPATTR_NOCONFIG) && 
  699                 PNPATTR_CONFIG(pd->attrib) != PNPATTR_CONFIG_STATIC)
  700                 ? ISACFGATTR_DYNAMIC : 0);
  701         ISA_SET_CONFIG_CALLBACK(parent, dev, pnpbios_set_config, 0);
  702         pnp_parse_resources(dev, &pd->devdata[0],
  703                             pd->size - sizeof(struct pnp_sysdev), 0);
  704         if (!device_get_desc(dev))
  705             device_set_desc_copy(dev, pnp_eisaformat(pd->devid));
  706 
  707         /* Find device IDs */
  708         devid = &pd->devid;
  709         compid = NULL;
  710 
  711         /* look for a compatible device ID too */
  712         left = pd->size - sizeof(struct pnp_sysdev);
  713         idx = 0;
  714         while (idx < left) {
  715             tag = pd->devdata[idx++];
  716             if (PNP_RES_TYPE(tag) == 0) {
  717                 /* Small resource */
  718                 switch (PNP_SRES_NUM(tag)) {
  719                 case PNP_TAG_COMPAT_DEVICE:
  720                     compid = (u_int32_t *)(pd->devdata + idx);
  721                     if (bootverbose)
  722                         printf("pnpbios: node %d compat ID 0x%08x\n", pd->handle, *compid);
  723                     /* FALLTHROUGH */
  724                 case PNP_TAG_END:
  725                     idx = left;
  726                     break;
  727                 default:
  728                     idx += PNP_SRES_LEN(tag);
  729                     break;
  730                 }
  731             } else
  732                 /* Large resource, skip it */
  733                 idx += *(u_int16_t *)(pd->devdata + idx) + 2;
  734         }
  735         if (bootverbose) {
  736             printf("pnpbios: handle %d device ID %s (%08x)", 
  737                    pd->handle, pnp_eisaformat(*devid), *devid);
  738             if (compid != NULL)
  739                 printf(" compat ID %s (%08x)",
  740                        pnp_eisaformat(*compid), *compid);
  741             printf("\n");
  742         }
  743     }
  744 }
  745 
  746 static device_method_t pnpbios_methods[] = {
  747         /* Device interface */
  748         DEVMETHOD(device_identify,      pnpbios_identify),
  749 
  750         { 0, 0 }
  751 };
  752 
  753 static driver_t pnpbios_driver = {
  754         "pnpbios",
  755         pnpbios_methods,
  756         1,                      /* no softc */
  757 };
  758 
  759 static devclass_t pnpbios_devclass;
  760 
  761 DRIVER_MODULE(pnpbios, isa, pnpbios_driver, pnpbios_devclass, 0, 0);
  762 #endif /* DEV_ISA */

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