NetBSD/sys/arch/mac68k/nubus/nubus.c

789 lines
19 KiB
C

/* $NetBSD: nubus.c,v 1.41 1997/08/11 22:53:37 scottr Exp $ */
/*
* Copyright (c) 1995, 1996 Allen Briggs. All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
* 3. All advertising materials mentioning features or use of this software
* must display the following acknowledgement:
* This product includes software developed by Allen Briggs.
* 4. The name of the author may not be used to endorse or promote products
* derived from this software without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
* IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
* OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
* IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
* NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
* DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
* THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
* THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*/
#include <sys/param.h>
#include <sys/systm.h>
#include <sys/device.h>
#include <sys/buf.h>
#include <sys/conf.h>
#include <sys/dmap.h>
#include <vm/vm.h>
#include <vm/vm_kern.h>
#include <vm/vm_map.h>
#include <machine/autoconf.h>
#include <machine/bus.h>
#include <machine/vmparam.h>
#include <machine/param.h>
#include <machine/cpu.h>
#include <machine/pte.h>
#include <machine/viareg.h>
#include <vm/vm.h>
#include <mac68k/dev/nubus.h>
#ifdef DEBUG
#define NDB_PROBE 0x1
#define NDB_FOLLOW 0x2
#define NDB_ARITH 0x4
static int nubus_debug = 0 /* | NDB_PROBE */;
#endif
static int nubus_print __P((void *, const char *));
static int nubus_match __P((struct device *, struct cfdata *, void *));
static void nubus_attach __P((struct device *, struct device *, void *));
static int nubus_video_resource __P((int));
static int nubus_probe_slot __P((bus_space_tag_t, bus_space_handle_t,
int, nubus_slot *));
static u_int32_t nubus_calc_CRC __P((bus_space_tag_t, bus_space_handle_t,
nubus_slot *));
static u_long nubus_adjust_ptr __P((u_int8_t, u_long, long));
static u_int8_t nubus_read_1 __P((bus_space_tag_t, bus_space_handle_t,
u_int8_t, u_long));
#ifdef notyet
static u_int16_t nubus_read_2 __P((bus_space_tag_t, bus_space_handle_t,
u_int8_t, u_long));
#endif
static u_int32_t nubus_read_4 __P((bus_space_tag_t, bus_space_handle_t,
u_int8_t, u_long));
struct cfattach nubus_ca = {
sizeof(struct nubus_softc), nubus_match, nubus_attach
};
struct cfdriver nubus_cd = {
NULL, "nubus", DV_DULL,
};
static int
nubus_match(parent, cf, aux)
struct device *parent;
struct cfdata *cf;
void *aux;
{
static int nubus_matched = 0;
/* Allow only one instance. */
if (nubus_matched)
return (0);
nubus_matched = 1;
return (1);
}
static void
nubus_attach(parent, self, aux)
struct device *parent, *self;
void *aux;
{
struct nubus_attach_args na_args;
bus_space_tag_t bst;
bus_space_handle_t bsh;
nubus_slot fmtblock;
nubus_dir dir;
nubus_dirent dirent;
nubus_type slottype;
u_long entry;
int i, rsrcid;
u_int8_t lanes;
printf("\n");
for (i = NUBUS_MIN_SLOT; i <= NUBUS_MAX_SLOT; i++) {
na_args.slot = i;
na_args.na_tag = bst = MAC68K_BUS_SPACE_MEM;
if (bus_space_map(bst,
NUBUS_SLOT2PA(na_args.slot), NBMEMSIZE, 0, &bsh)) {
#ifdef DIAGNOSTIC
printf("%s: failed to map slot %x, address %p\n",
self->dv_xname, i, (void *)NUBUS_SLOT2PA(i));
#endif
continue;
}
if (nubus_probe_slot(bst, bsh, i, &fmtblock) <= 0) {
notfound:
bus_space_unmap(bst, bsh, NBMEMSIZE);
continue;
}
rsrcid = 0x80;
lanes = fmtblock.bytelanes;
nubus_get_main_dir(&fmtblock, &dir);
/*
* Get the resource for the first function on the card.
* This is assumed to be at resource ID 0x80. If we can
* not find this entry (as we can not on some video cards),
* check to see if we can get a different ID from the list
* of video resources given to us by the booter. If that
* doesn't work either, take the first resource following
* the board resource.
*/
if (nubus_find_rsrc(bst, bsh,
&fmtblock, &dir, rsrcid, &dirent) <= 0) {
if ((rsrcid = nubus_video_resource(i)) == -1) {
/*
* Since nubus_find_rsrc failed, the directory
* is back at its base.
*/
entry = dir.curr_ent;
/*
* All nubus cards should have a board
* resource, but be sure that's what it
* is before we skip it.
*/
rsrcid = nubus_read_1(bst, bsh,
lanes, entry);
if (rsrcid == 0x1)
entry = nubus_adjust_ptr(lanes,
dir.curr_ent, 4);
rsrcid = nubus_read_1(bst, bsh, lanes, entry);
#ifdef DEBUG
if (nubus_debug & NDB_FOLLOW)
printf("\tUsing rsrc 0x%x.\n", rsrcid);
#endif
if (rsrcid == 0xff) /* end of chain */
goto notfound;
}
/*
* Try to find the resource passed by the booter
* or the one we just tracked down.
*/
if (nubus_find_rsrc(bst, bsh,
&fmtblock, &dir, rsrcid, &dirent) <= 0)
goto notfound;
}
nubus_get_dir_from_rsrc(&fmtblock, &dirent, &dir);
if (nubus_find_rsrc(bst, bsh,
&fmtblock, &dir, NUBUS_RSRC_TYPE, &dirent) <= 0)
goto notfound;
if (nubus_get_ind_data(bst, bsh, &fmtblock, &dirent,
(caddr_t)&slottype, sizeof(nubus_type)) <= 0)
goto notfound;
/*
* If this is a display card, try to pull out the correct
* display mode as passed by the booter.
*/
if (slottype.category == NUBUS_CATEGORY_DISPLAY) {
int r;
if ((r = nubus_video_resource(i)) != -1) {
nubus_get_main_dir(&fmtblock, &dir);
if (nubus_find_rsrc(bst, bsh,
&fmtblock, &dir, r, &dirent) <= 0)
goto notfound;
nubus_get_dir_from_rsrc(&fmtblock,
&dirent, &dir);
if (nubus_find_rsrc(bst, bsh, &fmtblock, &dir,
NUBUS_RSRC_TYPE, &dirent) <= 0)
goto notfound;
if (nubus_get_ind_data(bst, bsh,
&fmtblock, &dirent, (caddr_t)&slottype,
sizeof(nubus_type)) <= 0)
goto notfound;
rsrcid = r;
}
}
na_args.slot = i;
na_args.rsrcid = rsrcid;
na_args.category = slottype.category;
na_args.type = slottype.type;
na_args.drsw = slottype.drsw;
na_args.drhw = slottype.drhw;
na_args.fmt = &fmtblock;
bus_space_unmap(bst, bsh, NBMEMSIZE);
config_found(self, &na_args, nubus_print);
}
enable_nubus_intr();
}
static int
nubus_print(aux, pnp)
void *aux;
const char *pnp;
{
struct nubus_attach_args *na = (struct nubus_attach_args *)aux;
bus_space_tag_t bst = na->na_tag;
bus_space_handle_t bsh;
if (pnp) {
printf("%s slot %x", pnp, na->slot);
if (bus_space_map(bst,
NUBUS_SLOT2PA(na->slot), NBMEMSIZE, 0, &bsh) == 0) {
printf(": %s", nubus_get_card_name(bst, bsh, na->fmt));
printf(" (Vendor: %s,", nubus_get_vendor(bst, bsh,
na->fmt, NUBUS_RSRC_VEND_ID));
printf(" Part: %s)", nubus_get_vendor(bst, bsh,
na->fmt, NUBUS_RSRC_VEND_PART));
bus_space_unmap(bst, bsh, NBMEMSIZE);
}
#ifdef DIAGNOSTIC
else
printf(":");
printf(" Type: %04x %04x %04x %04x",
na->category, na->type, na->drsw, na->drhw);
#endif
} else {
printf(" slot %x", na->slot);
}
return (UNCONF);
}
static int
nubus_video_resource(slot)
int slot;
{
extern u_int16_t mac68k_vrsrc_vec[];
int i;
for (i = 0 ; i < 6 ; i++)
if ((mac68k_vrsrc_vec[i] & 0xff) == slot)
return ((mac68k_vrsrc_vec[i] >> 8) & 0xff);
return (-1);
}
/*
* Probe a given nubus slot. If a card is there and we can get the
* format block from it's clutching decl. ROMs, fill the format block
* and return non-zero. If we can't find a card there with a valid
* decl. ROM, return 0.
*
* First, we check to see if we can access the memory at the tail
* end of the slot. If so, then we check for a bytelanes byte. We
* could probably just return a failure status if we bus error on
* the first try, but there really is little reason not to go ahead
* and check the other three locations in case there's a wierd card
* out there.
*
* Checking for a card involves locating the "bytelanes" byte which
* tells us how to interpret the declaration ROM's data. The format
* block is at the top of the card's standard memory space and the
* bytelanes byte is at the end of that block.
*
* After some inspection of the bytelanes byte, it appears that it
* takes the form 0xXY where Y is a bitmask of the bytelanes in use
* and X is a bitmask of the lanes to ignore. Hence, (X ^ Y) == 0
* and (less obviously), Y will have the upper N bits clear if it is
* found N bytes from the last possible location. Both that and
* the exclusive-or check are made.
*
* If a valid
*/
static u_int8_t nbits[] = {0,1,1,2,1,2,2,3,1,2,2,3,2,3,3,4};
static int
nubus_probe_slot(bst, bsh, slot, fmt)
bus_space_tag_t bst;
bus_space_handle_t bsh;
int slot;
nubus_slot *fmt;
{
u_long ofs, hdr;
int i, j, found, hdr_size;
u_int8_t lanes;
#ifdef DEBUG
if (nubus_debug & NDB_PROBE)
printf("probing slot %x\n", slot);
#endif
/*
* The idea behind this glorious work of art is to probe for only
* valid bytelanes values at appropriate locations (see DC&D p. 159
* for a list). Note the pattern: the first 8 values are at offset
* 0xffffff in the slot's space; the next 4 values at 0xfffffe; the
* next 2 values at 0xfffffd; and the last one at 0xfffffc.
*
* The nested loops implement an efficient search of this space,
* probing first for a valid address, then checking for each of the
* valid bytelanes values at that address.
*/
ofs = NBMEMSIZE;
lanes = 0xf;
for (j = 8, found = 0; j > 0 && !found; j >>= 1) {
ofs--;
for (i = j; i > 0; i--, lanes--) {
if (!bus_probe(bst, bsh, ofs, 1)) {
lanes -= i;
break;
}
if (bus_space_read_1(bst, bsh, ofs) ==
(((~lanes & 0xf) << 4) | lanes)) {
found = 1;
break;
}
}
}
if (!found) {
#ifdef DEBUG
if (nubus_debug & NDB_PROBE)
printf("bytelanes not found for slot %x\n", slot);
#endif
return 0;
}
fmt->bytelanes = lanes;
fmt->step = nbits[(lanes & 0x0f)];
fmt->slot = slot; /* XXX redundant; get rid of this someday */
#ifdef DEBUG
if (nubus_debug & NDB_PROBE)
printf("bytelanes of 0x%x found for slot 0x%x.\n",
fmt->bytelanes, slot);
#endif
/*
* Go ahead and attempt to load format header.
* First, we need to find the first byte beyond memory that
* would be valid. This is necessary for NUBUS_ROM_offset()
* to work.
*/
hdr = NBMEMSIZE;
hdr_size = 20;
i = 0x10 | (lanes & 0x0f);
while ((i & 1) == 0) {
hdr++;
i >>= 1;
}
fmt->top = hdr;
hdr = nubus_adjust_ptr(lanes, hdr, -hdr_size);
#ifdef DEBUG
if (nubus_debug & NDB_PROBE)
printf("fmt->top is 0x%lx, that minus 0x%x puts us at 0x%lx.\n",
fmt->top, hdr_size, hdr);
if (nubus_debug & NDB_ARITH)
for (i = 1 ; i < 8 ; i++)
printf("0x%lx - 0x%x = 0x%lx, + 0x%x = 0x%lx.\n",
hdr, i, nubus_adjust_ptr(lanes, hdr, -i),
i, nubus_adjust_ptr(lanes, hdr, i));
#endif
fmt->directory_offset =
0xff000000 | nubus_read_4(bst, bsh, lanes, hdr);
hdr = nubus_adjust_ptr(lanes, hdr, 4);
fmt->length = nubus_read_4(bst, bsh, lanes, hdr);
hdr = nubus_adjust_ptr(lanes, hdr, 4);
fmt->crc = nubus_read_4(bst, bsh, lanes, hdr);
hdr = nubus_adjust_ptr(lanes, hdr, 4);
fmt->revision_level = nubus_read_1(bst, bsh, lanes, hdr);
hdr = nubus_adjust_ptr(lanes, hdr, 1);
fmt->format = nubus_read_1(bst, bsh, lanes, hdr);
hdr = nubus_adjust_ptr(lanes, hdr, 1);
fmt->test_pattern = nubus_read_4(bst, bsh, lanes, hdr);
#ifdef DEBUG
if (nubus_debug & NDB_PROBE) {
printf("Directory offset 0x%x\t", fmt->directory_offset);
printf("Length 0x%x\t", fmt->length);
printf("CRC 0x%x\n", fmt->crc);
printf("Revision level 0x%x\t", fmt->revision_level);
printf("Format 0x%x\t", fmt->format);
printf("Test Pattern 0x%x\n", fmt->test_pattern);
}
#endif
if ((fmt->directory_offset & 0x00ff0000) == 0) {
printf("Invalid looking directory offset (0x%x)!\n",
fmt->directory_offset);
return 0;
}
if (fmt->test_pattern != NUBUS_ROM_TEST_PATTERN) {
printf("Nubus--test pattern invalid:\n");
printf(" slot 0x%x, bytelanes 0x%x?\n", fmt->slot, lanes);
printf(" read test 0x%x, compare with 0x%x.\n",
fmt->test_pattern, NUBUS_ROM_TEST_PATTERN);
return 0;
}
/* Perform CRC */
if (fmt->crc != nubus_calc_CRC(bst, bsh, fmt)) {
printf("Nubus--crc check failed, slot 0x%x.\n", fmt->slot);
return 0;
}
return 1;
}
static u_int32_t
nubus_calc_CRC(bst, bsh, fmt)
bus_space_tag_t bst;
bus_space_handle_t bsh;
nubus_slot *fmt;
{
#if 0
u_long base, ptr, crc_loc;
u_int32_t sum;
u_int8_t lanes = fmt->bytelanes;
base = fmt->top;
crc_loc = NUBUS_ROM_offset(fmt, base, -12);
ptr = NUBUS_ROM_offset(fmt, base, -fmt->length);
sum = 0;
while (ptr < base)
roll #1, sum
if (ptr == crc_loc) {
roll #3, sum
ptr = nubus_adjust_ptr(lanes, ptr, 3);
} else {
sum += nubus_read_1(bst, bsh, lanes, ptr);
}
ptr = nubus_adjust_ptr(lanes, ptr, 1);
}
return sum;
#endif
return fmt->crc;
}
/*
* Compute byte offset on card, taking into account bytelanes.
* Base must be on a valid bytelane for this function to work.
* Return the new address.
*
* XXX -- There has GOT to be a better way to do this.
*/
static u_long
nubus_adjust_ptr(lanes, base, amt)
u_int8_t lanes;
u_long base;
long amt;
{
u_int8_t b, t;
if (!amt)
return base;
if (amt < 0) {
amt = -amt;
b = lanes;
t = (b << 4);
b <<= (3 - (base & 0x3));
while (amt) {
b <<= 1;
if (b == t)
b = lanes;
if (b & 0x08)
amt--;
base--;
}
return base;
}
t = (lanes & 0xf) | 0x10;
b = t >> (base & 0x3);
while (amt) {
b >>= 1;
if (b == 1)
b = t;
if (b & 1)
amt--;
base++;
}
return base;
}
static u_int8_t
nubus_read_1(bst, bsh, lanes, ofs)
bus_space_tag_t bst;
bus_space_handle_t bsh;
u_int8_t lanes;
u_long ofs;
{
return bus_space_read_1(bst, bsh, ofs);
}
#ifdef notyet
/* Nothing uses this, yet */
static u_int16_t
nubus_read_2(bst, bsh, lanes, ofs)
bus_space_tag_t bst;
bus_space_handle_t bsh;
u_int8_t lanes;
u_long ofs;
{
u_int16_t s;
s = (nubus_read_1(bst, bsh, lanes, ofs) << 8);
ofs = nubus_adjust_ptr(lanes, ofs, 1);
s |= nubus_read_1(bst, bsh, lanes, ofs);
return s;
}
#endif
static u_int32_t
nubus_read_4(bst, bsh, lanes, ofs)
bus_space_tag_t bst;
bus_space_handle_t bsh;
u_int8_t lanes;
u_long ofs;
{
u_int32_t l;
int i;
l = 0;
for (i = 0; i < 4; i++) {
l = (l << 8) | nubus_read_1(bst, bsh, lanes, ofs);
ofs = nubus_adjust_ptr(lanes, ofs, 1);
}
return l;
}
void
nubus_get_main_dir(fmt, dir_return)
nubus_slot *fmt;
nubus_dir *dir_return;
{
#ifdef DEBUG
if (nubus_debug & NDB_FOLLOW)
printf("nubus_get_main_dir(%p, %p)\n",
fmt, dir_return);
#endif
dir_return->dirbase = nubus_adjust_ptr(fmt->bytelanes, fmt->top,
fmt->directory_offset - 20);
dir_return->curr_ent = dir_return->dirbase;
}
void
nubus_get_dir_from_rsrc(fmt, dirent, dir_return)
nubus_slot *fmt;
nubus_dirent *dirent;
nubus_dir *dir_return;
{
u_long loc;
#ifdef DEBUG
if (nubus_debug & NDB_FOLLOW)
printf("nubus_get_dir_from_rsrc(%p, %p, %p).\n",
fmt, dirent, dir_return);
#endif
if ((loc = dirent->offset) & 0x800000) {
loc |= 0xff000000;
}
dir_return->dirbase =
nubus_adjust_ptr(fmt->bytelanes, dirent->myloc, loc);
dir_return->curr_ent = dir_return->dirbase;
}
int
nubus_find_rsrc(bst, bsh, fmt, dir, rsrcid, dirent_return)
bus_space_tag_t bst;
bus_space_handle_t bsh;
nubus_slot *fmt;
nubus_dir *dir;
u_int8_t rsrcid;
nubus_dirent *dirent_return;
{
u_long entry;
u_int8_t byte, lanes = fmt->bytelanes;
#ifdef DEBUG
if (nubus_debug & NDB_FOLLOW)
printf("nubus_find_rsrc(%p, %p, 0x%x, %p)\n",
fmt, dir, rsrcid, dirent_return);
#endif
if (fmt->test_pattern != NUBUS_ROM_TEST_PATTERN)
return -1;
entry = dir->curr_ent;
do {
byte = nubus_read_1(bst, bsh, lanes, entry);
#ifdef DEBUG
if (nubus_debug & NDB_FOLLOW)
printf("\tFound rsrc 0x%x.\n", byte);
#endif
if (byte == rsrcid) {
dirent_return->myloc = entry;
dirent_return->rsrc_id = rsrcid;
entry = nubus_read_4(bst, bsh, lanes, entry);
dirent_return->offset = (entry & 0x00ffffff);
return 1;
}
if (byte == 0xff) {
entry = dir->dirbase;
} else {
entry = nubus_adjust_ptr(lanes, entry, 4);
}
} while (entry != (u_long)dir->curr_ent);
return 0;
}
int
nubus_get_ind_data(bst, bsh, fmt, dirent, data_return, nbytes)
bus_space_tag_t bst;
bus_space_handle_t bsh;
nubus_slot *fmt;
nubus_dirent *dirent;
caddr_t data_return;
int nbytes;
{
u_long loc;
u_int8_t lanes = fmt->bytelanes;
#ifdef DEBUG
if (nubus_debug & NDB_FOLLOW)
printf("nubus_get_ind_data(%p, %p, %p, %d).\n",
fmt, dirent, data_return, nbytes);
#endif
if ((loc = dirent->offset) & 0x800000) {
loc |= 0xff000000;
}
loc = nubus_adjust_ptr(lanes, dirent->myloc, loc);
while (nbytes--) {
*data_return++ = nubus_read_1(bst, bsh, lanes, loc);
loc = nubus_adjust_ptr(lanes, loc, 1);
}
return 1;
}
int
nubus_get_c_string(bst, bsh, fmt, dirent, data_return, max_bytes)
bus_space_tag_t bst;
bus_space_handle_t bsh;
nubus_slot *fmt;
nubus_dirent *dirent;
caddr_t data_return;
int max_bytes;
{
u_long loc;
u_int8_t lanes = fmt->bytelanes;
#ifdef DEBUG
if (nubus_debug & NDB_FOLLOW)
printf("nubus_get_c_string(%p, %p, %p, %d).\n",
fmt, dirent, data_return, max_bytes);
#endif
if ((loc = dirent->offset) & 0x800000)
loc |= 0xff000000;
loc = nubus_adjust_ptr(lanes, dirent->myloc, loc);
*data_return = '\0';
while (max_bytes--) {
if ((*data_return++ =
nubus_read_1(bst, bsh, lanes, loc)) == 0)
return 1;
loc = nubus_adjust_ptr(lanes, loc, 1);
}
return 0;
}
static char *huh = "???";
char *
nubus_get_vendor(bst, bsh, fmt, rsrc)
bus_space_tag_t bst;
bus_space_handle_t bsh;
nubus_slot *fmt;
int rsrc;
{
static char str_ret[64];
nubus_dir dir;
nubus_dirent ent;
#ifdef DEBUG
if (nubus_debug & NDB_FOLLOW)
printf("nubus_get_vendor(%p, 0x%x).\n", fmt, rsrc);
#endif
nubus_get_main_dir(fmt, &dir);
if (nubus_find_rsrc(bst, bsh, fmt, &dir, 1, &ent) <= 0)
return huh;
nubus_get_dir_from_rsrc(fmt, &ent, &dir);
if (nubus_find_rsrc(bst, bsh, fmt, &dir, NUBUS_RSRC_VENDORINFO, &ent)
<= 0)
return huh;
nubus_get_dir_from_rsrc(fmt, &ent, &dir);
if (nubus_find_rsrc(bst, bsh, fmt, &dir, rsrc, &ent) <= 0)
return huh;
nubus_get_c_string(bst, bsh, fmt, &ent, str_ret, 64);
return str_ret;
}
char *
nubus_get_card_name(bst, bsh, fmt)
bus_space_tag_t bst;
bus_space_handle_t bsh;
nubus_slot *fmt;
{
static char name_ret[64];
nubus_dir dir;
nubus_dirent ent;
#ifdef DEBUG
if (nubus_debug & NDB_FOLLOW)
printf("nubus_get_card_name(%p).\n", fmt);
#endif
nubus_get_main_dir(fmt, &dir);
if (nubus_find_rsrc(bst, bsh, fmt, &dir, 1, &ent) <= 0)
return huh;
nubus_get_dir_from_rsrc(fmt, &ent, &dir);
if (nubus_find_rsrc(bst, bsh, fmt, &dir, NUBUS_RSRC_NAME, &ent) <= 0)
return huh;
nubus_get_c_string(bst, bsh, fmt, &ent, name_ret, 64);
return name_ret;
}