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cpu_subr.c revision 1.1
      1 /*	$NetBSD: cpu_subr.c,v 1.1 2003/02/03 17:10:09 matt Exp $	*/
      2 
      3 /*-
      4  * Copyright (c) 2001 Matt Thomas.
      5  * Copyright (c) 2001 Tsubai Masanari.
      6  * Copyright (c) 1998, 1999, 2001 Internet Research Institute, Inc.
      7  * All rights reserved.
      8  *
      9  * Redistribution and use in source and binary forms, with or without
     10  * modification, are permitted provided that the following conditions
     11  * are met:
     12  * 1. Redistributions of source code must retain the above copyright
     13  *    notice, this list of conditions and the following disclaimer.
     14  * 2. Redistributions in binary form must reproduce the above copyright
     15  *    notice, this list of conditions and the following disclaimer in the
     16  *    documentation and/or other materials provided with the distribution.
     17  * 3. All advertising materials mentioning features or use of this software
     18  *    must display the following acknowledgement:
     19  *	This product includes software developed by
     20  *	Internet Research Institute, Inc.
     21  * 4. The name of the author may not be used to endorse or promote products
     22  *    derived from this software without specific prior written permission.
     23  *
     24  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
     25  * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
     26  * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
     27  * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
     28  * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
     29  * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
     30  * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
     31  * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
     32  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
     33  * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
     34  */
     35 
     36 #include "opt_ppcparam.h"
     37 #include "opt_multiprocessor.h"
     38 #include "opt_altivec.h"
     39 #include "sysmon_envsys.h"
     40 
     41 #include <sys/param.h>
     42 #include <sys/systm.h>
     43 #include <sys/device.h>
     44 
     45 #include <uvm/uvm_extern.h>
     46 
     47 #include <powerpc/oea/hid.h>
     48 #include <powerpc/oea/hid_601.h>
     49 #include <powerpc/spr.h>
     50 
     51 #include <dev/sysmon/sysmonvar.h>
     52 
     53 static void cpu_config_l2cr(int);
     54 static void cpu_print_speed(void);
     55 #if NSYSMON_ENVSYS > 0
     56 static void cpu_tau_setup(struct cpu_info *);
     57 static int cpu_tau_gtredata __P((struct sysmon_envsys *,
     58     struct envsys_tre_data *));
     59 static int cpu_tau_streinfo __P((struct sysmon_envsys *,
     60     struct envsys_basic_info *));
     61 #endif
     62 
     63 int cpu;
     64 int ncpus;
     65 
     66 #ifdef MULTIPROCESSOR
     67 struct cpu_info cpu_info[CPU_MAXNUM];
     68 #else
     69 struct cpu_info cpu_info[1];
     70 #endif
     71 
     72 int cpu_altivec;
     73 char cpu_model[80];
     74 
     75 void
     76 cpu_probe_cache(void)
     77 {
     78 	u_int assoc, pvr, vers;
     79 
     80 	pvr = mfpvr();
     81 	vers = pvr >> 16;
     82 
     83 	switch (vers) {
     84 #define	K	*1024
     85 	case IBM750FX:
     86 	case MPC601:
     87 	case MPC750:
     88 	case MPC7450:
     89 	case MPC7455:
     90 		curcpu()->ci_ci.dcache_size = 32 K;
     91 		curcpu()->ci_ci.icache_size = 32 K;
     92 		assoc = 8;
     93 		break;
     94 	case MPC603:
     95 		curcpu()->ci_ci.dcache_size = 8 K;
     96 		curcpu()->ci_ci.icache_size = 8 K;
     97 		assoc = 2;
     98 		break;
     99 	case MPC603e:
    100 	case MPC603ev:
    101 	case MPC604:
    102 	case MPC8240:
    103 	case MPC8245:
    104 		curcpu()->ci_ci.dcache_size = 16 K;
    105 		curcpu()->ci_ci.icache_size = 16 K;
    106 		assoc = 4;
    107 		break;
    108 	case MPC604ev:
    109 		curcpu()->ci_ci.dcache_size = 32 K;
    110 		curcpu()->ci_ci.icache_size = 32 K;
    111 		assoc = 4;
    112 		break;
    113 	default:
    114 		curcpu()->ci_ci.dcache_size = NBPG;
    115 		curcpu()->ci_ci.icache_size = NBPG;
    116 		assoc = 1;
    117 #undef	K
    118 	}
    119 
    120 	/* Presently common across all implementations. */
    121 	curcpu()->ci_ci.dcache_line_size = CACHELINESIZE;
    122 	curcpu()->ci_ci.icache_line_size = CACHELINESIZE;
    123 
    124 	/*
    125 	 * Possibly recolor.
    126 	 */
    127 	uvm_page_recolor(atop(curcpu()->ci_ci.dcache_size / assoc));
    128 }
    129 
    130 struct cpu_info *
    131 cpu_attach_common(struct device *self, int id)
    132 {
    133 	struct cpu_info *ci;
    134 	u_int pvr, vers;
    135 
    136 	ncpus++;
    137 	ci = &cpu_info[id];
    138 #ifndef MULTIPROCESSOR
    139 	/*
    140 	 * If this isn't the primary CPU, print an error message
    141 	 * and just bail out.
    142 	 */
    143 	if (id != 0) {
    144 		printf(": ID %d\n", id);
    145 		printf("%s: processor off-line; multiprocessor support "
    146 		    "not present in kernel\n", self->dv_xname);
    147 		return (NULL);
    148 	}
    149 #endif
    150 
    151 	ci->ci_cpuid = id;
    152 	ci->ci_intrdepth = -1;
    153 	ci->ci_dev = self;
    154 
    155 	pvr = mfpvr();
    156 	vers = (pvr >> 16) & 0xffff;
    157 
    158 	switch (id) {
    159 	case 0:
    160 		/* load my cpu_number to PIR */
    161 		switch (vers) {
    162 		case MPC601:
    163 		case MPC604:
    164 		case MPC604ev:
    165 		case MPC7400:
    166 		case MPC7410:
    167 		case MPC7450:
    168 		case MPC7455:
    169 			mtspr(SPR_PIR, id);
    170 		}
    171 		cpu_setup(self, ci);
    172 		break;
    173 	default:
    174 		if (id >= CPU_MAXNUM) {
    175 			printf(": more than %d cpus?\n", CPU_MAXNUM);
    176 			panic("cpuattach");
    177 		}
    178 #ifndef MULTIPROCESSOR
    179 		printf(" not configured\n");
    180 		return NULL;
    181 #endif
    182 	}
    183 	return (ci);
    184 }
    185 
    186 void
    187 cpu_setup(self, ci)
    188 	struct device *self;
    189 	struct cpu_info *ci;
    190 {
    191 	u_int hid0, pvr, vers;
    192 	char *bitmask, hidbuf[128];
    193 	char model[80];
    194 
    195 	pvr = mfpvr();
    196 	vers = (pvr >> 16) & 0xffff;
    197 
    198 	cpu_identify(model, sizeof(model));
    199 	printf(": %s, ID %d%s\n", model,  cpu_number(),
    200 	    cpu_number() == 0 ? " (primary)" : "");
    201 
    202 	hid0 = mfspr(SPR_HID0);
    203 	cpu_probe_cache();
    204 
    205 	/*
    206 	 * Configure power-saving mode.
    207 	 */
    208 	switch (vers) {
    209 	case MPC603:
    210 	case MPC603e:
    211 	case MPC603ev:
    212 	case MPC604ev:
    213 	case MPC750:
    214 	case IBM750FX:
    215 	case MPC7400:
    216 	case MPC7410:
    217 	case MPC8240:
    218 	case MPC8245:
    219 		/* Select DOZE mode. */
    220 		hid0 &= ~(HID0_DOZE | HID0_NAP | HID0_SLEEP);
    221 		hid0 |= HID0_DOZE | HID0_DPM;
    222 		powersave = 1;
    223 		break;
    224 
    225 	case MPC7455:
    226 	case MPC7450:
    227 		/* Disable BTIC on 7450 Rev 2.0 or earlier */
    228 		if ((pvr >> 16) == MPC7450 && (pvr & 0xFFFF) <= 0x0200)
    229 			hid0 &= ~HID0_BTIC;
    230 		/* Select NAP mode. */
    231 		hid0 &= ~(HID0_DOZE | HID0_NAP | HID0_SLEEP);
    232 		hid0 |= HID0_NAP | HID0_DPM;
    233 		powersave = 0;		/* but don't use it */
    234 		break;
    235 
    236 	default:
    237 		/* No power-saving mode is available. */ ;
    238 	}
    239 
    240 #ifdef NAPMODE
    241 	switch (vers) {
    242 	case IBM750FX:
    243 	case MPC750:
    244 	case MPC7400:
    245 		/* Select NAP mode. */
    246 		hid0 &= ~(HID0_DOZE | HID0_NAP | HID0_SLEEP);
    247 		hid0 |= HID0_NAP;
    248 		break;
    249 	}
    250 #endif
    251 
    252 	switch (vers) {
    253 	case IBM750FX:
    254 	case MPC750:
    255 		hid0 &= ~HID0_DBP;		/* XXX correct? */
    256 		hid0 |= HID0_EMCP | HID0_BTIC | HID0_SGE | HID0_BHT;
    257 		break;
    258 
    259 	case MPC7400:
    260 	case MPC7410:
    261 		hid0 &= ~HID0_SPD;
    262 		hid0 |= HID0_EMCP | HID0_BTIC | HID0_SGE | HID0_BHT;
    263 		hid0 |= HID0_EIEC;
    264 		break;
    265 	}
    266 
    267 	mtspr(SPR_HID0, hid0);
    268 
    269 	switch (vers) {
    270 	case MPC601:
    271 		bitmask = HID0_601_BITMASK;
    272 		break;
    273 	case MPC7450:
    274 	case MPC7455:
    275 		bitmask = HID0_7450_BITMASK;
    276 		break;
    277 	default:
    278 		bitmask = HID0_BITMASK;
    279 		break;
    280 	}
    281 	bitmask_snprintf(hid0, bitmask, hidbuf, sizeof hidbuf);
    282 	printf("%s: HID0 %s\n", self->dv_xname, hidbuf);
    283 
    284 	/*
    285 	 * Display speed and cache configuration.
    286 	 */
    287 	if (vers == MPC750 || vers == MPC7400 || vers == IBM750FX ||
    288 	    vers == MPC7410 || vers == MPC7450 || vers == MPC7455) {
    289 		printf("%s", self->dv_xname);
    290 		cpu_print_speed();
    291 		printf("%s", self->dv_xname);
    292 		cpu_config_l2cr(vers);
    293 	}
    294 
    295 #if NSYSMON_ENVSYS > 0
    296 	/*
    297 	 * Attach MPC750 temperature sensor to the envsys subsystem.
    298 	 * XXX the 74xx series also has this sensor, but it is not
    299 	 * XXX supported by Motorola and may return values that are off by
    300 	 * XXX 35-55 degrees C.
    301 	 */
    302 	if (vers == MPC750 || vers == IBM750FX)
    303 		cpu_tau_setup(ci);
    304 #endif
    305 
    306 	evcnt_attach_dynamic(&ci->ci_ev_clock, EVCNT_TYPE_INTR,
    307 		NULL, self->dv_xname, "clock");
    308 	evcnt_attach_dynamic(&ci->ci_ev_softclock, EVCNT_TYPE_INTR,
    309 		NULL, self->dv_xname, "soft clock");
    310 	evcnt_attach_dynamic(&ci->ci_ev_softnet, EVCNT_TYPE_INTR,
    311 		NULL, self->dv_xname, "soft net");
    312 	evcnt_attach_dynamic(&ci->ci_ev_softserial, EVCNT_TYPE_INTR,
    313 		NULL, self->dv_xname, "soft serial");
    314 	evcnt_attach_dynamic(&ci->ci_ev_traps, EVCNT_TYPE_TRAP,
    315 		NULL, self->dv_xname, "traps");
    316 	evcnt_attach_dynamic(&ci->ci_ev_kdsi, EVCNT_TYPE_TRAP,
    317 		&ci->ci_ev_traps, self->dv_xname, "kernel DSI traps");
    318 	evcnt_attach_dynamic(&ci->ci_ev_udsi, EVCNT_TYPE_TRAP,
    319 		&ci->ci_ev_traps, self->dv_xname, "user DSI traps");
    320 	evcnt_attach_dynamic(&ci->ci_ev_udsi_fatal, EVCNT_TYPE_TRAP,
    321 		&ci->ci_ev_udsi, self->dv_xname, "user DSI failures");
    322 	evcnt_attach_dynamic(&ci->ci_ev_isi, EVCNT_TYPE_TRAP,
    323 		&ci->ci_ev_traps, self->dv_xname, "user ISI traps");
    324 	evcnt_attach_dynamic(&ci->ci_ev_isi_fatal, EVCNT_TYPE_TRAP,
    325 		&ci->ci_ev_isi, self->dv_xname, "user ISI failures");
    326 	evcnt_attach_dynamic(&ci->ci_ev_scalls, EVCNT_TYPE_TRAP,
    327 		&ci->ci_ev_traps, self->dv_xname, "system call traps");
    328 	evcnt_attach_dynamic(&ci->ci_ev_pgm, EVCNT_TYPE_TRAP,
    329 		&ci->ci_ev_traps, self->dv_xname, "PGM traps");
    330 	evcnt_attach_dynamic(&ci->ci_ev_fpu, EVCNT_TYPE_TRAP,
    331 		&ci->ci_ev_traps, self->dv_xname, "FPU unavailable traps");
    332 	evcnt_attach_dynamic(&ci->ci_ev_fpusw, EVCNT_TYPE_TRAP,
    333 		&ci->ci_ev_fpu, self->dv_xname, "FPU context switches");
    334 	evcnt_attach_dynamic(&ci->ci_ev_ali, EVCNT_TYPE_TRAP,
    335 		&ci->ci_ev_traps, self->dv_xname, "user alignment traps");
    336 	evcnt_attach_dynamic(&ci->ci_ev_ali_fatal, EVCNT_TYPE_TRAP,
    337 		&ci->ci_ev_ali, self->dv_xname, "user alignment traps");
    338 	evcnt_attach_dynamic(&ci->ci_ev_umchk, EVCNT_TYPE_TRAP,
    339 		&ci->ci_ev_umchk, self->dv_xname, "user MCHK failures");
    340 	evcnt_attach_dynamic(&ci->ci_ev_vec, EVCNT_TYPE_TRAP,
    341 		&ci->ci_ev_traps, self->dv_xname, "AltiVec unavailable");
    342 #ifdef ALTIVEC
    343 	if (cpu_altivec) {
    344 		evcnt_attach_dynamic(&ci->ci_ev_vecsw, EVCNT_TYPE_TRAP,
    345 		    &ci->ci_ev_vec, self->dv_xname, "AltiVec context switches");
    346 	}
    347 #endif
    348 }
    349 
    350 struct cputab {
    351 	const char name[8];
    352 	uint16_t version;
    353 	uint16_t revfmt;
    354 };
    355 #define	REVFMT_MAJMIN	1		/* %u.%u */
    356 #define	REVFMT_HEX	2		/* 0x%04x */
    357 #define	REVFMT_DEC	3		/* %u */
    358 static const struct cputab models[] = {
    359 	{ "601",	MPC601,		REVFMT_DEC },
    360 	{ "602",	MPC602,		REVFMT_DEC },
    361 	{ "603",	MPC603,		REVFMT_MAJMIN },
    362 	{ "603e",	MPC603e,	REVFMT_MAJMIN },
    363 	{ "603ev",	MPC603ev,	REVFMT_MAJMIN },
    364 	{ "604",	MPC604,		REVFMT_MAJMIN },
    365 	{ "604ev",	MPC604ev,	REVFMT_MAJMIN },
    366 	{ "620",	MPC620,  	REVFMT_HEX },
    367 	{ "750",	MPC750,		REVFMT_MAJMIN },
    368 	{ "750FX",	IBM750FX,	REVFMT_MAJMIN },
    369 	{ "7400",	MPC7400,	REVFMT_MAJMIN },
    370 	{ "7410",	MPC7410,	REVFMT_MAJMIN },
    371 	{ "7450",	MPC7450,	REVFMT_MAJMIN },
    372 	{ "7455",	MPC7455,	REVFMT_MAJMIN },
    373 	{ "8240",	MPC8240,	REVFMT_MAJMIN },
    374 	{ "",		0,		REVFMT_HEX }
    375 };
    376 
    377 void
    378 cpu_identify(char *str, size_t len)
    379 {
    380 	u_int pvr, maj, min;
    381 	uint16_t vers, rev, revfmt;
    382 	const struct cputab *cp;
    383 	const char *name;
    384 	size_t n;
    385 
    386 	pvr = mfpvr();
    387 	vers = pvr >> 16;
    388 	rev = pvr;
    389 	switch (vers) {
    390 	case MPC7410:
    391 		min = (pvr >> 0) & 0xff;
    392 		maj = min <= 4 ? 1 : 2;
    393 		break;
    394 	default:
    395 		maj = (pvr >>  8) & 0xf;
    396 		min = (pvr >>  0) & 0xf;
    397 	}
    398 
    399 	for (cp = models; cp->name[0] != '\0'; cp++) {
    400 		if (cp->version == vers)
    401 			break;
    402 	}
    403 
    404 	if (str == NULL) {
    405 		str = cpu_model;
    406 		len = sizeof(cpu_model);
    407 		cpu = vers;
    408 	}
    409 
    410 	revfmt = cp->revfmt;
    411 	name = cp->name;
    412 	if (rev == MPC750 && pvr == 15) {
    413 		name = "755";
    414 		revfmt = REVFMT_HEX;
    415 	}
    416 
    417 	if (cp->name[0] != '\0') {
    418 		n = snprintf(str, len, "%s (Revision ", cp->name);
    419 	} else {
    420 		n = snprintf(str, len, "Version %#x (Revision ", vers);
    421 	}
    422 	if (len > n) {
    423 		switch (revfmt) {
    424 		case REVFMT_MAJMIN:
    425 			snprintf(str + n, len - n, "%u.%u)", maj, min);
    426 			break;
    427 		case REVFMT_HEX:
    428 			snprintf(str + n, len - n, "0x%04x)", rev);
    429 			break;
    430 		case REVFMT_DEC:
    431 			snprintf(str + n, len - n, "%u)", rev);
    432 			break;
    433 		}
    434 	}
    435 }
    436 
    437 #ifdef L2CR_CONFIG
    438 u_int l2cr_config = L2CR_CONFIG;
    439 #else
    440 u_int l2cr_config = 0;
    441 #endif
    442 
    443 void
    444 cpu_config_l2cr(int vers)
    445 {
    446 	u_int l2cr, x, msr;
    447 
    448 	l2cr = mfspr(SPR_L2CR);
    449 
    450 	/*
    451 	 * For MP systems, the firmware may only configure the L2 cache
    452 	 * on the first CPU.  In this case, assume that the other CPUs
    453 	 * should use the same value for L2CR.
    454 	 */
    455 	if ((l2cr & L2CR_L2E) != 0 && l2cr_config == 0) {
    456 		l2cr_config = l2cr;
    457 	}
    458 
    459 	/*
    460 	 * Configure L2 cache if not enabled.
    461 	 */
    462 	if ((l2cr & L2CR_L2E) == 0 && l2cr_config != 0) {
    463 		l2cr = l2cr_config;
    464 
    465 		/* Disable interrupts and set the cache config bits. */
    466 		msr = mfmsr();
    467 		mtmsr(msr & ~PSL_EE);
    468 #ifdef ALTIVEC
    469 		if (cpu_altivec)
    470 			__asm __volatile("dssall");
    471 #endif
    472 		__asm __volatile("sync");
    473 		mtspr(SPR_L2CR, l2cr & ~L2CR_L2E);
    474 		__asm __volatile("sync");
    475 
    476 		/* Wait for L2 clock to be stable (640 L2 clocks). */
    477 		delay(100);
    478 
    479 		/* Invalidate all L2 contents. */
    480 		mtspr(SPR_L2CR, l2cr | L2CR_L2I);
    481 		do {
    482 			x = mfspr(SPR_L2CR);
    483 		} while (x & L2CR_L2IP);
    484 
    485 		/* Enable L2 cache. */
    486 		l2cr |= L2CR_L2E;
    487 		mtspr(SPR_L2CR, l2cr);
    488 		mtmsr(msr);
    489 	}
    490 
    491 	if (l2cr & L2CR_L2E) {
    492 		if (vers == MPC7450 || vers == MPC7455) {
    493 			u_int l3cr;
    494 
    495 			printf(": 256KB L2 cache");
    496 
    497 			l3cr = mfspr(SPR_L3CR);
    498 			if (l3cr & L3CR_L3E)
    499 				printf(", %cMB L3 backside cache",
    500 				   l3cr & L3CR_L3SIZ ? '2' : '1');
    501 			printf("\n");
    502 			return;
    503 		}
    504 		if (vers == IBM750FX) {
    505 			printf(": 512KB L2 cache\n");
    506 			return;
    507 		}
    508 		switch (l2cr & L2CR_L2SIZ) {
    509 		case L2SIZ_256K:
    510 			printf(": 256KB");
    511 			break;
    512 		case L2SIZ_512K:
    513 			printf(": 512KB");
    514 			break;
    515 		case L2SIZ_1M:
    516 			printf(": 1MB");
    517 			break;
    518 		default:
    519 			printf(": unknown size");
    520 		}
    521 		if (l2cr & L2CR_L2WT) {
    522 			printf(" write-through");
    523 		} else {
    524 			printf(" write-back");
    525 		}
    526 		switch (l2cr & L2CR_L2RAM) {
    527 		case L2RAM_FLOWTHRU_BURST:
    528 			printf(" Flow-through synchronous burst SRAM");
    529 			break;
    530 		case L2RAM_PIPELINE_BURST:
    531 			printf(" Pipelined synchronous burst SRAM");
    532 			break;
    533 		case L2RAM_PIPELINE_LATE:
    534 			printf(" Pipelined synchronous late-write SRAM");
    535 			break;
    536 		default:
    537 			printf(" unknown type");
    538 		}
    539 
    540 		if (l2cr & L2CR_L2PE)
    541 			printf(" with parity");
    542 		printf(" backside cache");
    543 	} else
    544 		printf(": L2 cache not enabled");
    545 
    546 	printf("\n");
    547 }
    548 
    549 void
    550 cpu_print_speed(void)
    551 {
    552 	uint64_t cps;
    553 
    554 	mtspr(SPR_MMCR0, SPR_MMCR0_FC);
    555 	mtspr(SPR_PMC1, 0);
    556 	mtspr(SPR_MMCR0, SPR_MMCR0_PMC1SEL(PMCN_CYCLES));
    557 	delay(100000);
    558 	cps = (mfspr(SPR_PMC1) * 10) + 4999;
    559 
    560 	printf(": %lld.%02lld MHz\n", cps / 1000000, (cps / 10000) % 100);
    561 }
    562 
    563 #if NSYSMON_ENVSYS > 0
    564 const struct envsys_range cpu_tau_ranges[] = {
    565 	{ 0, 0, ENVSYS_STEMP}
    566 };
    567 
    568 struct envsys_basic_info cpu_tau_info[] = {
    569 	{ 0, ENVSYS_STEMP, "CPU temp", 0, 0, ENVSYS_FVALID}
    570 };
    571 
    572 void
    573 cpu_tau_setup(struct cpu_info *ci)
    574 {
    575 	struct sysmon_envsys *sme;
    576 	int error;
    577 
    578 	sme = &ci->ci_sysmon;
    579 	sme->sme_nsensors = 1;
    580 	sme->sme_envsys_version = 1000;
    581 	sme->sme_ranges = cpu_tau_ranges;
    582 	sme->sme_sensor_info = cpu_tau_info;
    583 	sme->sme_sensor_data = &ci->ci_tau_info;
    584 
    585 	sme->sme_sensor_data->sensor = 0;
    586 	sme->sme_sensor_data->warnflags = ENVSYS_WARN_OK;
    587 	sme->sme_sensor_data->validflags = ENVSYS_FVALID|ENVSYS_FCURVALID;
    588 	sme->sme_cookie = ci;
    589 	sme->sme_gtredata = cpu_tau_gtredata;
    590 	sme->sme_streinfo = cpu_tau_streinfo;
    591 
    592 	if ((error = sysmon_envsys_register(sme)) != 0)
    593 		printf("%s: unable to register with sysmon (%d)\n",
    594 		    ci->ci_dev->dv_xname, error);
    595 }
    596 
    597 
    598 /* Find the temperature of the CPU. */
    599 int
    600 cpu_tau_gtredata(sme, tred)
    601 	 struct sysmon_envsys *sme;
    602 	 struct envsys_tre_data *tred;
    603 {
    604 	struct cpu_info *ci;
    605 	int i, threshold, count;
    606 
    607 	if (tred->sensor != 0) {
    608 		tred->validflags = 0;
    609 		return 0;
    610 	}
    611 
    612 	threshold = 64; /* Half of the 7-bit sensor range */
    613 	mtspr(SPR_THRM1, 0);
    614 	mtspr(SPR_THRM2, 0);
    615 	/* XXX This counter is supposed to be "at least 20 microseonds, in
    616 	 * XXX units of clock cycles". Since we don't have convenient
    617 	 * XXX access to the CPU speed, set it to a conservative value,
    618 	 * XXX that is, assuming a fast (1GHz) G3 CPU (As of February 2002,
    619 	 * XXX the fastest G3 processor is 700MHz) . The cost is that
    620 	 * XXX measuring the temperature takes a bit longer.
    621 	 */
    622         mtspr(SPR_THRM3, SPR_THRM_TIMER(20000) | SPR_THRM_ENABLE);
    623 
    624 	/* Successive-approximation code adapted from Motorola
    625 	 * application note AN1800/D, "Programming the Thermal Assist
    626 	 * Unit in the MPC750 Microprocessor".
    627 	 */
    628 	for (i = 4; i >= 0 ; i--) {
    629 		mtspr(SPR_THRM1,
    630 		    SPR_THRM_THRESHOLD(threshold) | SPR_THRM_VALID);
    631 		count = 0;
    632 		while ((count < 100) &&
    633 		    ((mfspr(SPR_THRM1) & SPR_THRM_TIV) == 0)) {
    634 			count++;
    635 			delay(1);
    636 		}
    637 		if (mfspr(SPR_THRM1) & SPR_THRM_TIN) {
    638 			/* The interrupt bit was set, meaning the
    639 			 * temperature was above the threshold
    640 			 */
    641 			threshold += 2 << i;
    642 		} else {
    643 			/* Temperature was below the threshold */
    644 			threshold -= 2 << i;
    645 		}
    646 	}
    647 	threshold += 2;
    648 
    649 	ci = (struct cpu_info *)sme->sme_cookie;
    650 	/* Convert the temperature in degrees C to microkelvin */
    651 	ci->ci_tau_info.cur.data_us = (threshold * 1000000) + 273150000;
    652 
    653 	*tred = ci->ci_tau_info;
    654 
    655 	return 0;
    656 }
    657 
    658 int
    659 cpu_tau_streinfo(sme, binfo)
    660 	 struct sysmon_envsys *sme;
    661 	 struct envsys_basic_info *binfo;
    662 {
    663 
    664 	/* There is nothing to set here. */
    665 	return (EINVAL);
    666 }
    667 #endif /* NSYSMON_ENVSYS > 0 */
    668