xref: /freebsd/sys/dev/acpica/acpi_cpu.c (revision 2546665afcaf0d53dc2c7058fee96354b3680f5a)
1 /*-
2  * Copyright (c) 2003 Nate Lawson (SDG)
3  * Copyright (c) 2001 Michael Smith
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 #include "opt_acpi.h"
32 #include <sys/param.h>
33 #include <sys/bus.h>
34 #include <sys/kernel.h>
35 #include <sys/malloc.h>
36 #include <sys/module.h>
37 #include <sys/pcpu.h>
38 #include <sys/power.h>
39 #include <sys/proc.h>
40 #include <sys/sbuf.h>
41 #include <sys/smp.h>
42 
43 #include <dev/pci/pcivar.h>
44 #include <machine/atomic.h>
45 #include <machine/bus.h>
46 #ifdef __ia64__
47 #include <machine/pal.h>
48 #endif
49 #include <sys/rman.h>
50 
51 #include "acpi.h"
52 #include <dev/acpica/acpivar.h>
53 
54 /*
55  * Support for ACPI Processor devices, including ACPI 2.0 throttling
56  * and C[1-3] sleep states.
57  *
58  * TODO: implement scans of all CPUs to be sure all Cx states are
59  * equivalent.
60  */
61 
62 /* Hooks for the ACPI CA debugging infrastructure */
63 #define _COMPONENT	ACPI_PROCESSOR
64 ACPI_MODULE_NAME("PROCESSOR")
65 
66 struct acpi_cx {
67     struct resource	*p_lvlx;	/* Register to read to enter state. */
68     uint32_t		 type;		/* C1-3 (C4 and up treated as C3). */
69     uint32_t		 trans_lat;	/* Transition latency (usec). */
70     uint32_t		 power;		/* Power consumed (mW). */
71 };
72 #define MAX_CX_STATES	 8
73 
74 struct acpi_cpu_softc {
75     device_t		 cpu_dev;
76     ACPI_HANDLE		 cpu_handle;
77     uint32_t		 acpi_id;	/* ACPI processor id */
78     uint32_t		 cpu_p_blk;	/* ACPI P_BLK location */
79     uint32_t		 cpu_p_blk_len;	/* P_BLK length (must be 6). */
80     struct resource	*cpu_p_cnt;	/* Throttling control register */
81     struct acpi_cx	 cpu_cx_states[MAX_CX_STATES];
82     int			 cpu_cx_count;	/* Number of valid Cx states. */
83     int			 cpu_prev_sleep;/* Last idle sleep duration. */
84 };
85 
86 #define CPU_GET_REG(reg, width) 					\
87     (bus_space_read_ ## width(rman_get_bustag((reg)), 			\
88 		      rman_get_bushandle((reg)), 0))
89 #define CPU_SET_REG(reg, width, val)					\
90     (bus_space_write_ ## width(rman_get_bustag((reg)), 			\
91 		       rman_get_bushandle((reg)), 0, (val)))
92 
93 /*
94  * Speeds are stored in counts, from 1 to CPU_MAX_SPEED, and
95  * reported to the user in tenths of a percent.
96  */
97 static uint32_t		 cpu_duty_offset;
98 static uint32_t		 cpu_duty_width;
99 #define CPU_MAX_SPEED		(1 << cpu_duty_width)
100 #define CPU_SPEED_PERCENT(x)	((1000 * (x)) / CPU_MAX_SPEED)
101 #define CPU_SPEED_PRINTABLE(x)	(CPU_SPEED_PERCENT(x) / 10),	\
102 				(CPU_SPEED_PERCENT(x) % 10)
103 #define CPU_P_CNT_THT_EN (1<<4)
104 #define PM_USEC(x)	 ((x) >> 2)	/* ~4 clocks per usec (3.57955 Mhz) */
105 
106 #define ACPI_CPU_NOTIFY_PERF_STATES	0x80	/* _PSS changed. */
107 #define ACPI_CPU_NOTIFY_CX_STATES	0x81	/* _CST changed. */
108 
109 #define CPU_QUIRK_NO_C3		0x0001	/* C3-type states are not usable. */
110 #define CPU_QUIRK_NO_THROTTLE	0x0002	/* Throttling is not usable. */
111 
112 #define PCI_VENDOR_INTEL	0x8086
113 #define PCI_DEVICE_82371AB_3	0x7113	/* PIIX4 chipset for quirks. */
114 #define PCI_REVISION_A_STEP	0
115 #define PCI_REVISION_B_STEP	1
116 #define PCI_REVISION_4E		2
117 #define PCI_REVISION_4M		3
118 
119 /* Platform hardware resource information. */
120 static uint32_t		 cpu_smi_cmd;	/* Value to write to SMI_CMD. */
121 static uint8_t		 cpu_pstate_cnt;/* Register to take over throttling. */
122 static uint8_t		 cpu_cst_cnt;	/* Indicate we are _CST aware. */
123 static int		 cpu_rid;	/* Driver-wide resource id. */
124 static int		 cpu_quirks;	/* Indicate any hardware bugs. */
125 
126 /* Runtime state. */
127 static int		 cpu_cx_count;	/* Number of valid states */
128 static int		 cpu_non_c3;	/* Index of lowest non-C3 state. */
129 static u_int		 cpu_cx_stats[MAX_CX_STATES];/* Cx usage history. */
130 
131 /* Values for sysctl. */
132 static uint32_t		 cpu_throttle_state;
133 static uint32_t		 cpu_throttle_max;
134 static int		 cpu_cx_lowest;
135 static char 		 cpu_cx_supported[64];
136 
137 static device_t		*cpu_devices;
138 static int		 cpu_ndevices;
139 static struct acpi_cpu_softc **cpu_softc;
140 
141 static struct sysctl_ctx_list	acpi_cpu_sysctl_ctx;
142 static struct sysctl_oid	*acpi_cpu_sysctl_tree;
143 
144 static int	acpi_cpu_probe(device_t dev);
145 static int	acpi_cpu_attach(device_t dev);
146 static int	acpi_pcpu_get_id(uint32_t idx, uint32_t *acpi_id,
147 				 uint32_t *cpu_id);
148 static int	acpi_cpu_shutdown(device_t dev);
149 static int	acpi_cpu_throttle_probe(struct acpi_cpu_softc *sc);
150 static int	acpi_cpu_cx_probe(struct acpi_cpu_softc *sc);
151 static int	acpi_cpu_cx_cst(struct acpi_cpu_softc *sc);
152 static void	acpi_cpu_startup(void *arg);
153 static void	acpi_cpu_startup_throttling(void);
154 static void	acpi_cpu_startup_cx(void);
155 static void	acpi_cpu_throttle_set(uint32_t speed);
156 static void	acpi_cpu_idle(void);
157 static void	acpi_cpu_c1(void);
158 static void	acpi_cpu_notify(ACPI_HANDLE h, UINT32 notify, void *context);
159 static int	acpi_cpu_quirks(struct acpi_cpu_softc *sc);
160 static int	acpi_cpu_throttle_sysctl(SYSCTL_HANDLER_ARGS);
161 static int	acpi_cpu_usage_sysctl(SYSCTL_HANDLER_ARGS);
162 static int	acpi_cpu_cx_lowest_sysctl(SYSCTL_HANDLER_ARGS);
163 
164 static device_method_t acpi_cpu_methods[] = {
165     /* Device interface */
166     DEVMETHOD(device_probe,	acpi_cpu_probe),
167     DEVMETHOD(device_attach,	acpi_cpu_attach),
168     DEVMETHOD(device_shutdown,	acpi_cpu_shutdown),
169 
170     {0, 0}
171 };
172 
173 static driver_t acpi_cpu_driver = {
174     "cpu",
175     acpi_cpu_methods,
176     sizeof(struct acpi_cpu_softc),
177 };
178 
179 static devclass_t acpi_cpu_devclass;
180 DRIVER_MODULE(cpu, acpi, acpi_cpu_driver, acpi_cpu_devclass, 0, 0);
181 MODULE_DEPEND(cpu, acpi, 1, 1, 1);
182 
183 static int
184 acpi_cpu_probe(device_t dev)
185 {
186     int			   acpi_id, cpu_id, cx_count;
187     ACPI_BUFFER		   buf;
188     ACPI_HANDLE		   handle;
189     char		   msg[32];
190     ACPI_OBJECT		   *obj;
191     ACPI_STATUS		   status;
192 
193     if (acpi_disabled("cpu") || acpi_get_type(dev) != ACPI_TYPE_PROCESSOR)
194 	return (ENXIO);
195 
196     handle = acpi_get_handle(dev);
197     if (cpu_softc == NULL)
198 	cpu_softc = malloc(sizeof(struct acpi_cpu_softc *) *
199 	    (mp_maxid + 1), M_TEMP /* XXX */, M_WAITOK | M_ZERO);
200 
201     /* Get our Processor object. */
202     buf.Pointer = NULL;
203     buf.Length = ACPI_ALLOCATE_BUFFER;
204     status = AcpiEvaluateObject(handle, NULL, NULL, &buf);
205     if (ACPI_FAILURE(status)) {
206 	device_printf(dev, "probe failed to get Processor obj - %s\n",
207 		      AcpiFormatException(status));
208 	return (ENXIO);
209     }
210     obj = (ACPI_OBJECT *)buf.Pointer;
211     if (obj->Type != ACPI_TYPE_PROCESSOR) {
212 	device_printf(dev, "Processor object has bad type %d\n", obj->Type);
213 	AcpiOsFree(obj);
214 	return (ENXIO);
215     }
216 
217     /*
218      * Find the processor associated with our unit.  We could use the
219      * ProcId as a key, however, some boxes do not have the same values
220      * in their Processor object as the ProcId values in the MADT.
221      */
222     acpi_id = obj->Processor.ProcId;
223     AcpiOsFree(obj);
224     if (acpi_pcpu_get_id(device_get_unit(dev), &acpi_id, &cpu_id) != 0)
225 	return (ENXIO);
226 
227     /*
228      * Check if we already probed this processor.  We scan the bus twice
229      * so it's possible we've already seen this one.
230      */
231     if (cpu_softc[cpu_id] != NULL)
232 	return (ENXIO);
233 
234     /* Get a count of Cx states for our device string. */
235     cx_count = 0;
236     buf.Pointer = NULL;
237     buf.Length = ACPI_ALLOCATE_BUFFER;
238     status = AcpiEvaluateObject(handle, "_CST", NULL, &buf);
239     if (ACPI_SUCCESS(status)) {
240 	obj = (ACPI_OBJECT *)buf.Pointer;
241 	if (ACPI_PKG_VALID(obj, 2))
242 	    acpi_PkgInt32(obj, 0, &cx_count);
243 	AcpiOsFree(obj);
244     } else {
245 	if (AcpiGbl_FADT->Plvl2Lat <= 100)
246 	    cx_count++;
247 	if (AcpiGbl_FADT->Plvl3Lat <= 1000)
248 	    cx_count++;
249 	if (cx_count > 0)
250 	    cx_count++;
251     }
252     if (cx_count > 0)
253 	snprintf(msg, sizeof(msg), "ACPI CPU (%d Cx states)", cx_count);
254     else
255 	strlcpy(msg, "ACPI CPU", sizeof(msg));
256     device_set_desc_copy(dev, msg);
257 
258     /* Mark this processor as in-use and save our derived id for attach. */
259     cpu_softc[cpu_id] = (void *)1;
260     acpi_set_magic(dev, cpu_id);
261 
262     return (0);
263 }
264 
265 static int
266 acpi_cpu_attach(device_t dev)
267 {
268     ACPI_BUFFER		   buf;
269     ACPI_OBJECT		   *obj;
270     struct acpi_cpu_softc *sc;
271     struct acpi_softc	  *acpi_sc;
272     ACPI_STATUS		   status;
273     int			   thr_ret, cx_ret;
274 
275     ACPI_FUNCTION_TRACE((char *)(uintptr_t)__func__);
276 
277     ACPI_ASSERTLOCK;
278 
279     sc = device_get_softc(dev);
280     sc->cpu_dev = dev;
281     sc->cpu_handle = acpi_get_handle(dev);
282     cpu_softc[acpi_get_magic(dev)] = sc;
283 
284     buf.Pointer = NULL;
285     buf.Length = ACPI_ALLOCATE_BUFFER;
286     status = AcpiEvaluateObject(sc->cpu_handle, NULL, NULL, &buf);
287     if (ACPI_FAILURE(status)) {
288 	device_printf(dev, "attach failed to get Processor obj - %s\n",
289 		      AcpiFormatException(status));
290 	return (ENXIO);
291     }
292     obj = (ACPI_OBJECT *)buf.Pointer;
293     sc->cpu_p_blk = obj->Processor.PblkAddress;
294     sc->cpu_p_blk_len = obj->Processor.PblkLength;
295     sc->acpi_id = obj->Processor.ProcId;
296     AcpiOsFree(obj);
297     ACPI_DEBUG_PRINT((ACPI_DB_INFO, "acpi_cpu%d: P_BLK at %#x/%d\n",
298 		     device_get_unit(dev), sc->cpu_p_blk, sc->cpu_p_blk_len));
299 
300     acpi_sc = acpi_device_get_parent_softc(dev);
301     sysctl_ctx_init(&acpi_cpu_sysctl_ctx);
302     acpi_cpu_sysctl_tree = SYSCTL_ADD_NODE(&acpi_cpu_sysctl_ctx,
303 				SYSCTL_CHILDREN(acpi_sc->acpi_sysctl_tree),
304 				OID_AUTO, "cpu", CTLFLAG_RD, 0, "");
305 
306     /* If this is the first device probed, check for quirks. */
307     if (device_get_unit(dev) == 0)
308 	acpi_cpu_quirks(sc);
309 
310     /*
311      * Probe for throttling and Cx state support.
312      * If none of these is present, free up unused resources.
313      */
314     thr_ret = acpi_cpu_throttle_probe(sc);
315     cx_ret = acpi_cpu_cx_probe(sc);
316     if (thr_ret == 0 || cx_ret == 0) {
317 	status = AcpiInstallNotifyHandler(sc->cpu_handle, ACPI_DEVICE_NOTIFY,
318 					  acpi_cpu_notify, sc);
319 	if (device_get_unit(dev) == 0)
320 	    AcpiOsQueueForExecution(OSD_PRIORITY_LO, acpi_cpu_startup, NULL);
321     } else {
322 	sysctl_ctx_free(&acpi_cpu_sysctl_ctx);
323     }
324 
325     return_VALUE (0);
326 }
327 
328 /*
329  * Find the nth present CPU and return its pc_cpuid as well as set the
330  * pc_acpi_id from the most reliable source.
331  */
332 static int
333 acpi_pcpu_get_id(uint32_t idx, uint32_t *acpi_id, uint32_t *cpu_id)
334 {
335     struct pcpu	*pcpu_data;
336     uint32_t	 i;
337 
338     KASSERT(acpi_id != NULL, ("Null acpi_id"));
339     KASSERT(cpu_id != NULL, ("Null cpu_id"));
340     for (i = 0; i <= mp_maxid; i++) {
341 	if (CPU_ABSENT(i))
342 	    continue;
343 	pcpu_data = pcpu_find(i);
344 	KASSERT(pcpu_data != NULL, ("no pcpu data for %d", i));
345 	if (idx-- == 0) {
346 	    /*
347 	     * If pc_acpi_id was not initialized (e.g., a non-APIC UP box)
348 	     * override it with the value from the ASL.  Otherwise, if the
349 	     * two don't match, prefer the MADT-derived value.  Finally,
350 	     * return the pc_cpuid to reference this processor.
351 	     */
352 	    if (pcpu_data->pc_acpi_id == 0xffffffff)
353 		 pcpu_data->pc_acpi_id = *acpi_id;
354 	    else if (pcpu_data->pc_acpi_id != *acpi_id)
355 		*acpi_id = pcpu_data->pc_acpi_id;
356 	    *cpu_id = pcpu_data->pc_cpuid;
357 	    return (0);
358 	}
359     }
360 
361     return (ESRCH);
362 }
363 
364 static int
365 acpi_cpu_shutdown(device_t dev)
366 {
367     ACPI_FUNCTION_TRACE((char *)(uintptr_t)__func__);
368 
369     /* Disable any entry to the idle function. */
370     cpu_cx_count = 0;
371 
372     /* Signal and wait for all processors to exit acpi_cpu_idle(). */
373     smp_rendezvous(NULL, NULL, NULL, NULL);
374 
375     return_VALUE (0);
376 }
377 
378 static int
379 acpi_cpu_throttle_probe(struct acpi_cpu_softc *sc)
380 {
381     uint32_t		 duty_end;
382     ACPI_BUFFER		 buf;
383     ACPI_OBJECT		 obj;
384     ACPI_GENERIC_ADDRESS gas;
385     ACPI_STATUS		 status;
386 
387     ACPI_FUNCTION_TRACE((char *)(uintptr_t)__func__);
388 
389     ACPI_ASSERTLOCK;
390 
391     /* Get throttling parameters from the FADT.  0 means not supported. */
392     if (device_get_unit(sc->cpu_dev) == 0) {
393 	cpu_smi_cmd = AcpiGbl_FADT->SmiCmd;
394 	cpu_pstate_cnt = AcpiGbl_FADT->PstateCnt;
395 	cpu_cst_cnt = AcpiGbl_FADT->CstCnt;
396 	cpu_duty_offset = AcpiGbl_FADT->DutyOffset;
397 	cpu_duty_width = AcpiGbl_FADT->DutyWidth;
398     }
399     if (cpu_duty_width == 0 || (cpu_quirks & CPU_QUIRK_NO_THROTTLE) != 0)
400 	return (ENXIO);
401 
402     /* Validate the duty offset/width. */
403     duty_end = cpu_duty_offset + cpu_duty_width - 1;
404     if (duty_end > 31) {
405 	device_printf(sc->cpu_dev, "CLK_VAL field overflows P_CNT register\n");
406 	return (ENXIO);
407     }
408     if (cpu_duty_offset <= 4 && duty_end >= 4) {
409 	device_printf(sc->cpu_dev, "CLK_VAL field overlaps THT_EN bit\n");
410 	return (ENXIO);
411     }
412 
413     /*
414      * If not present, fall back to using the processor's P_BLK to find
415      * the P_CNT register.
416      *
417      * Note that some systems seem to duplicate the P_BLK pointer
418      * across multiple CPUs, so not getting the resource is not fatal.
419      */
420     buf.Pointer = &obj;
421     buf.Length = sizeof(obj);
422     status = AcpiEvaluateObject(sc->cpu_handle, "_PTC", NULL, &buf);
423     if (ACPI_SUCCESS(status)) {
424 	if (obj.Buffer.Length < sizeof(ACPI_GENERIC_ADDRESS) + 3) {
425 	    device_printf(sc->cpu_dev, "_PTC buffer too small\n");
426 	    return (ENXIO);
427 	}
428 	memcpy(&gas, obj.Buffer.Pointer + 3, sizeof(gas));
429 	sc->cpu_p_cnt = acpi_bus_alloc_gas(sc->cpu_dev, &cpu_rid, &gas);
430 	if (sc->cpu_p_cnt != NULL) {
431 	    ACPI_DEBUG_PRINT((ACPI_DB_INFO, "acpi_cpu%d: P_CNT from _PTC\n",
432 			     device_get_unit(sc->cpu_dev)));
433 	}
434     }
435 
436     /* If _PTC not present or other failure, try the P_BLK. */
437     if (sc->cpu_p_cnt == NULL) {
438 	/*
439 	 * The spec says P_BLK must be 6 bytes long.  However, some
440 	 * systems use it to indicate a fractional set of features
441 	 * present so we take anything >= 4.
442 	 */
443 	if (sc->cpu_p_blk_len < 4)
444 	    return (ENXIO);
445 	gas.Address = sc->cpu_p_blk;
446 	gas.AddressSpaceId = ACPI_ADR_SPACE_SYSTEM_IO;
447 	gas.RegisterBitWidth = 32;
448 	sc->cpu_p_cnt = acpi_bus_alloc_gas(sc->cpu_dev, &cpu_rid, &gas);
449 	if (sc->cpu_p_cnt != NULL) {
450 	    ACPI_DEBUG_PRINT((ACPI_DB_INFO, "acpi_cpu%d: P_CNT from P_BLK\n",
451 			     device_get_unit(sc->cpu_dev)));
452 	} else {
453 	    device_printf(sc->cpu_dev, "Failed to attach throttling P_CNT\n");
454 	    return (ENXIO);
455 	}
456     }
457     cpu_rid++;
458 
459     return (0);
460 }
461 
462 static int
463 acpi_cpu_cx_probe(struct acpi_cpu_softc *sc)
464 {
465     ACPI_GENERIC_ADDRESS gas;
466     struct acpi_cx	*cx_ptr;
467     int			 error;
468 
469     ACPI_FUNCTION_TRACE((char *)(uintptr_t)__func__);
470 
471     /* Bus mastering arbitration control is needed for C3. */
472     if (AcpiGbl_FADT->V1_Pm2CntBlk == 0 || AcpiGbl_FADT->Pm2CntLen == 0) {
473 	cpu_quirks |= CPU_QUIRK_NO_C3;
474 	ACPI_DEBUG_PRINT((ACPI_DB_INFO,
475 			 "acpi_cpu%d: No BM control, C3 disabled\n",
476 			 device_get_unit(sc->cpu_dev)));
477     }
478 
479     /*
480      * First, check for the ACPI 2.0 _CST sleep states object.
481      * If not usable, fall back to the P_BLK's P_LVL2 and P_LVL3.
482      */
483     sc->cpu_cx_count = 0;
484     error = acpi_cpu_cx_cst(sc);
485     if (error != 0) {
486 	cx_ptr = sc->cpu_cx_states;
487 
488 	/* C1 has been required since just after ACPI 1.0 */
489 	cx_ptr->type = ACPI_STATE_C1;
490 	cx_ptr->trans_lat = 0;
491 	cpu_non_c3 = 0;
492 	cx_ptr++;
493 	sc->cpu_cx_count++;
494 
495 	/*
496 	 * The spec says P_BLK must be 6 bytes long.  However, some systems
497 	 * use it to indicate a fractional set of features present so we
498 	 * take 5 as C2.  Some may also have a value of 7 to indicate
499 	 * another C3 but most use _CST for this (as required) and having
500 	 * "only" C1-C3 is not a hardship.
501 	 */
502 	if (sc->cpu_p_blk_len < 5)
503 	    goto done;
504 
505 	/* Validate and allocate resources for C2 (P_LVL2). */
506 	gas.AddressSpaceId = ACPI_ADR_SPACE_SYSTEM_IO;
507 	gas.RegisterBitWidth = 8;
508 	if (AcpiGbl_FADT->Plvl2Lat <= 100) {
509 	    gas.Address = sc->cpu_p_blk + 4;
510 	    cx_ptr->p_lvlx = acpi_bus_alloc_gas(sc->cpu_dev, &cpu_rid, &gas);
511 	    if (cx_ptr->p_lvlx != NULL) {
512 		cpu_rid++;
513 		cx_ptr->type = ACPI_STATE_C2;
514 		cx_ptr->trans_lat = AcpiGbl_FADT->Plvl2Lat;
515 		cpu_non_c3 = 1;
516 		cx_ptr++;
517 		sc->cpu_cx_count++;
518 	    }
519 	}
520 	if (sc->cpu_p_blk_len < 6)
521 	    goto done;
522 
523 	/* Validate and allocate resources for C3 (P_LVL3). */
524 	if (AcpiGbl_FADT->Plvl3Lat <= 1000 &&
525 	    (cpu_quirks & CPU_QUIRK_NO_C3) == 0) {
526 
527 	    gas.Address = sc->cpu_p_blk + 5;
528 	    cx_ptr->p_lvlx = acpi_bus_alloc_gas(sc->cpu_dev, &cpu_rid, &gas);
529 	    if (cx_ptr->p_lvlx != NULL) {
530 		cpu_rid++;
531 		cx_ptr->type = ACPI_STATE_C3;
532 		cx_ptr->trans_lat = AcpiGbl_FADT->Plvl3Lat;
533 		cx_ptr++;
534 		sc->cpu_cx_count++;
535 	    }
536 	}
537     }
538 
539 done:
540     /* If no valid registers were found, don't attach. */
541     if (sc->cpu_cx_count == 0)
542 	return (ENXIO);
543 
544     /* Use initial sleep value of 1 sec. to start with lowest idle state. */
545     sc->cpu_prev_sleep = 1000000;
546 
547     return (0);
548 }
549 
550 /*
551  * Parse a _CST package and set up its Cx states.  Since the _CST object
552  * can change dynamically, our notify handler may call this function
553  * to clean up and probe the new _CST package.
554  */
555 static int
556 acpi_cpu_cx_cst(struct acpi_cpu_softc *sc)
557 {
558     struct	 acpi_cx *cx_ptr;
559     ACPI_STATUS	 status;
560     ACPI_BUFFER	 buf;
561     ACPI_OBJECT	*top;
562     ACPI_OBJECT	*pkg;
563     uint32_t	 count;
564     int		 i;
565 
566     ACPI_FUNCTION_TRACE((char *)(uintptr_t)__func__);
567 
568     buf.Pointer = NULL;
569     buf.Length = ACPI_ALLOCATE_BUFFER;
570     status = AcpiEvaluateObject(sc->cpu_handle, "_CST", NULL, &buf);
571     if (ACPI_FAILURE(status))
572 	return (ENXIO);
573 
574     /* _CST is a package with a count and at least one Cx package. */
575     top = (ACPI_OBJECT *)buf.Pointer;
576     if (!ACPI_PKG_VALID(top, 2) || acpi_PkgInt32(top, 0, &count) != 0) {
577 	device_printf(sc->cpu_dev, "Invalid _CST package\n");
578 	AcpiOsFree(buf.Pointer);
579 	return (ENXIO);
580     }
581     if (count != top->Package.Count - 1) {
582 	device_printf(sc->cpu_dev, "Invalid _CST state count (%d != %d)\n",
583 	       count, top->Package.Count - 1);
584 	count = top->Package.Count - 1;
585     }
586     if (count > MAX_CX_STATES) {
587 	device_printf(sc->cpu_dev, "_CST has too many states (%d)\n", count);
588 	count = MAX_CX_STATES;
589     }
590 
591     /* Set up all valid states. */
592     sc->cpu_cx_count = 0;
593     cx_ptr = sc->cpu_cx_states;
594     for (i = 0; i < count; i++) {
595 	pkg = &top->Package.Elements[i + 1];
596 	if (!ACPI_PKG_VALID(pkg, 4) ||
597 	    acpi_PkgInt32(pkg, 1, &cx_ptr->type) != 0 ||
598 	    acpi_PkgInt32(pkg, 2, &cx_ptr->trans_lat) != 0 ||
599 	    acpi_PkgInt32(pkg, 3, &cx_ptr->power) != 0) {
600 
601 	    device_printf(sc->cpu_dev, "Skipping invalid Cx state package\n");
602 	    continue;
603 	}
604 
605 	/* Validate the state to see if we should use it. */
606 	switch (cx_ptr->type) {
607 	case ACPI_STATE_C1:
608 	    cpu_non_c3 = i;
609 	    cx_ptr++;
610 	    sc->cpu_cx_count++;
611 	    continue;
612 	case ACPI_STATE_C2:
613 	    if (cx_ptr->trans_lat > 100) {
614 		ACPI_DEBUG_PRINT((ACPI_DB_INFO,
615 				 "acpi_cpu%d: C2[%d] not available.\n",
616 				 device_get_unit(sc->cpu_dev), i));
617 		continue;
618 	    }
619 	    cpu_non_c3 = i;
620 	    break;
621 	case ACPI_STATE_C3:
622 	default:
623 	    if (cx_ptr->trans_lat > 1000 ||
624 		(cpu_quirks & CPU_QUIRK_NO_C3) != 0) {
625 
626 		ACPI_DEBUG_PRINT((ACPI_DB_INFO,
627 				 "acpi_cpu%d: C3[%d] not available.\n",
628 				 device_get_unit(sc->cpu_dev), i));
629 		continue;
630 	    }
631 	    break;
632 	}
633 
634 #ifdef notyet
635 	/* Free up any previous register. */
636 	if (cx_ptr->p_lvlx != NULL) {
637 	    bus_release_resource(sc->cpu_dev, 0, 0, cx_ptr->p_lvlx);
638 	    cx_ptr->p_lvlx = NULL;
639 	}
640 #endif
641 
642 	/* Allocate the control register for C2 or C3. */
643 	acpi_PkgGas(sc->cpu_dev, pkg, 0, &cpu_rid, &cx_ptr->p_lvlx);
644 	if (cx_ptr->p_lvlx != NULL) {
645 	    cpu_rid++;
646 	    ACPI_DEBUG_PRINT((ACPI_DB_INFO,
647 			     "acpi_cpu%d: Got C%d - %d latency\n",
648 			     device_get_unit(sc->cpu_dev), cx_ptr->type,
649 			     cx_ptr->trans_lat));
650 	    cx_ptr++;
651 	    sc->cpu_cx_count++;
652 	}
653     }
654     AcpiOsFree(buf.Pointer);
655 
656     return (0);
657 }
658 
659 /*
660  * Call this *after* all CPUs have been attached.
661  */
662 static void
663 acpi_cpu_startup(void *arg)
664 {
665     struct acpi_cpu_softc *sc;
666     int count, i;
667 
668     /* Get set of CPU devices */
669     devclass_get_devices(acpi_cpu_devclass, &cpu_devices, &cpu_ndevices);
670 
671     /*
672      * Make sure all the processors' Cx counts match.  We should probably
673      * also check the contents of each.  However, no known systems have
674      * non-matching Cx counts so we'll deal with this later.
675      */
676     count = MAX_CX_STATES;
677     for (i = 0; i < cpu_ndevices; i++) {
678 	sc = device_get_softc(cpu_devices[i]);
679 	count = min(sc->cpu_cx_count, count);
680     }
681     cpu_cx_count = count;
682 
683     /* Perform throttling and Cx final initialization. */
684     sc = device_get_softc(cpu_devices[0]);
685     if (sc->cpu_p_cnt != NULL)
686 	acpi_cpu_startup_throttling();
687     if (cpu_cx_count > 0)
688 	acpi_cpu_startup_cx();
689 }
690 
691 /*
692  * Takes the ACPI lock to avoid fighting anyone over the SMI command
693  * port.
694  */
695 static void
696 acpi_cpu_startup_throttling()
697 {
698     ACPI_LOCK_DECL;
699 
700     /* Initialise throttling states */
701     cpu_throttle_max = CPU_MAX_SPEED;
702     cpu_throttle_state = CPU_MAX_SPEED;
703 
704     SYSCTL_ADD_INT(&acpi_cpu_sysctl_ctx,
705 		   SYSCTL_CHILDREN(acpi_cpu_sysctl_tree),
706 		   OID_AUTO, "throttle_max", CTLFLAG_RD,
707 		   &cpu_throttle_max, 0, "maximum CPU speed");
708     SYSCTL_ADD_PROC(&acpi_cpu_sysctl_ctx,
709 		    SYSCTL_CHILDREN(acpi_cpu_sysctl_tree),
710 		    OID_AUTO, "throttle_state",
711 		    CTLTYPE_INT | CTLFLAG_RW, &cpu_throttle_state,
712 		    0, acpi_cpu_throttle_sysctl, "I", "current CPU speed");
713 
714     /* If ACPI 2.0+, signal platform that we are taking over throttling. */
715     ACPI_LOCK;
716     if (cpu_pstate_cnt != 0)
717 	AcpiOsWritePort(cpu_smi_cmd, cpu_pstate_cnt, 8);
718 
719     /* Set initial speed to maximum. */
720     acpi_cpu_throttle_set(cpu_throttle_max);
721     ACPI_UNLOCK;
722 
723     printf("acpi_cpu: throttling enabled, %d steps (100%% to %d.%d%%), "
724 	   "currently %d.%d%%\n", CPU_MAX_SPEED, CPU_SPEED_PRINTABLE(1),
725 	   CPU_SPEED_PRINTABLE(cpu_throttle_state));
726 }
727 
728 static void
729 acpi_cpu_startup_cx()
730 {
731     struct acpi_cpu_softc *sc;
732     struct sbuf		 sb;
733     int i;
734     ACPI_LOCK_DECL;
735 
736     sc = device_get_softc(cpu_devices[0]);
737     sbuf_new(&sb, cpu_cx_supported, sizeof(cpu_cx_supported), SBUF_FIXEDLEN);
738     for (i = 0; i < cpu_cx_count; i++)
739 	sbuf_printf(&sb, "C%d/%d ", i + 1, sc->cpu_cx_states[i].trans_lat);
740     sbuf_trim(&sb);
741     sbuf_finish(&sb);
742     SYSCTL_ADD_STRING(&acpi_cpu_sysctl_ctx,
743 		      SYSCTL_CHILDREN(acpi_cpu_sysctl_tree),
744 		      OID_AUTO, "cx_supported", CTLFLAG_RD, cpu_cx_supported,
745 		      0, "Cx/microsecond values for supported Cx states");
746     SYSCTL_ADD_PROC(&acpi_cpu_sysctl_ctx,
747 		    SYSCTL_CHILDREN(acpi_cpu_sysctl_tree),
748 		    OID_AUTO, "cx_lowest", CTLTYPE_STRING | CTLFLAG_RW,
749 		    NULL, 0, acpi_cpu_cx_lowest_sysctl, "A",
750 		    "lowest Cx sleep state to use");
751     SYSCTL_ADD_PROC(&acpi_cpu_sysctl_ctx,
752 		    SYSCTL_CHILDREN(acpi_cpu_sysctl_tree),
753 		    OID_AUTO, "cx_usage", CTLTYPE_STRING | CTLFLAG_RD,
754 		    NULL, 0, acpi_cpu_usage_sysctl, "A",
755 		    "percent usage for each Cx state");
756 
757 #ifdef notyet
758     /* Signal platform that we can handle _CST notification. */
759     if (cpu_cst_cnt != 0) {
760 	ACPI_LOCK;
761 	AcpiOsWritePort(cpu_smi_cmd, cpu_cst_cnt, 8);
762 	ACPI_UNLOCK;
763     }
764 #endif
765 
766     /* Take over idling from cpu_idle_default(). */
767     cpu_idle_hook = acpi_cpu_idle;
768 }
769 
770 /*
771  * Set CPUs to the new state.
772  *
773  * Must be called with the ACPI lock held.
774  */
775 static void
776 acpi_cpu_throttle_set(uint32_t speed)
777 {
778     struct acpi_cpu_softc	*sc;
779     int				i;
780     uint32_t			p_cnt, clk_val;
781 
782     ACPI_ASSERTLOCK;
783 
784     /* Iterate over processors */
785     for (i = 0; i < cpu_ndevices; i++) {
786 	sc = device_get_softc(cpu_devices[i]);
787 	if (sc->cpu_p_cnt == NULL)
788 	    continue;
789 
790 	/* Get the current P_CNT value and disable throttling */
791 	p_cnt = CPU_GET_REG(sc->cpu_p_cnt, 4);
792 	p_cnt &= ~CPU_P_CNT_THT_EN;
793 	CPU_SET_REG(sc->cpu_p_cnt, 4, p_cnt);
794 
795 	/* If we're at maximum speed, that's all */
796 	if (speed < CPU_MAX_SPEED) {
797 	    /* Mask the old CLK_VAL off and or-in the new value */
798 	    clk_val = (CPU_MAX_SPEED - 1) << cpu_duty_offset;
799 	    p_cnt &= ~clk_val;
800 	    p_cnt |= (speed << cpu_duty_offset);
801 
802 	    /* Write the new P_CNT value and then enable throttling */
803 	    CPU_SET_REG(sc->cpu_p_cnt, 4, p_cnt);
804 	    p_cnt |= CPU_P_CNT_THT_EN;
805 	    CPU_SET_REG(sc->cpu_p_cnt, 4, p_cnt);
806 	}
807 	ACPI_VPRINT(sc->cpu_dev, acpi_device_get_parent_softc(sc->cpu_dev),
808 		    "set speed to %d.%d%%\n", CPU_SPEED_PRINTABLE(speed));
809     }
810     cpu_throttle_state = speed;
811 }
812 
813 /*
814  * Idle the CPU in the lowest state possible.  This function is called with
815  * interrupts disabled.  Note that once it re-enables interrupts, a task
816  * switch can occur so do not access shared data (i.e. the softc) after
817  * interrupts are re-enabled.
818  */
819 static void
820 acpi_cpu_idle()
821 {
822     struct	acpi_cpu_softc *sc;
823     struct	acpi_cx *cx_next;
824     uint32_t	start_time, end_time;
825     int		bm_active, cx_next_idx, i;
826 
827     /* If disabled, return immediately. */
828     if (cpu_cx_count == 0) {
829 	ACPI_ENABLE_IRQS();
830 	return;
831     }
832 
833     /*
834      * Look up our CPU id to get our softc.  If it's NULL, we'll use C1
835      * since there is no ACPI processor object for this CPU.  This occurs
836      * for logical CPUs in the HTT case.
837      */
838     sc = cpu_softc[PCPU_GET(cpuid)];
839     if (sc == NULL) {
840 	acpi_cpu_c1();
841 	return;
842     }
843 
844     /*
845      * If we slept 100 us or more, use the lowest Cx state.  Otherwise,
846      * find the lowest state that has a latency less than or equal to
847      * the length of our last sleep.
848      */
849     cx_next_idx = cpu_cx_lowest;
850     if (sc->cpu_prev_sleep < 100)
851 	for (i = cpu_cx_lowest; i >= 0; i--)
852 	    if (sc->cpu_cx_states[i].trans_lat <= sc->cpu_prev_sleep) {
853 		cx_next_idx = i;
854 		break;
855 	    }
856 
857     /*
858      * Check for bus master activity.  If there was activity, clear
859      * the bit and use the lowest non-C3 state.  Note that the USB
860      * driver polling for new devices keeps this bit set all the
861      * time if USB is loaded.
862      */
863     AcpiGetRegister(ACPI_BITREG_BUS_MASTER_STATUS, &bm_active,
864 		    ACPI_MTX_DO_NOT_LOCK);
865     if (bm_active != 0) {
866 	AcpiSetRegister(ACPI_BITREG_BUS_MASTER_STATUS, 1,
867 			ACPI_MTX_DO_NOT_LOCK);
868 	cx_next_idx = min(cx_next_idx, cpu_non_c3);
869     }
870 
871     /* Select the next state and update statistics. */
872     cx_next = &sc->cpu_cx_states[cx_next_idx];
873     cpu_cx_stats[cx_next_idx]++;
874     KASSERT(cx_next->type != ACPI_STATE_C0, ("acpi_cpu_idle: C0 sleep"));
875 
876     /*
877      * Execute HLT (or equivalent) and wait for an interrupt.  We can't
878      * calculate the time spent in C1 since the place we wake up is an
879      * ISR.  Assume we slept one quantum and return.
880      */
881     if (cx_next->type == ACPI_STATE_C1) {
882 	sc->cpu_prev_sleep = 1000000 / hz;
883 	acpi_cpu_c1();
884 	return;
885     }
886 
887     /* For C3, disable bus master arbitration and enable bus master wake. */
888     if (cx_next->type == ACPI_STATE_C3) {
889 	AcpiSetRegister(ACPI_BITREG_ARB_DISABLE, 1, ACPI_MTX_DO_NOT_LOCK);
890 	AcpiSetRegister(ACPI_BITREG_BUS_MASTER_RLD, 1, ACPI_MTX_DO_NOT_LOCK);
891     }
892 
893     /*
894      * Read from P_LVLx to enter C2(+), checking time spent asleep.
895      * Use the ACPI timer for measuring sleep time.  Since we need to
896      * get the time very close to the CPU start/stop clock logic, this
897      * is the only reliable time source.
898      */
899     AcpiHwLowLevelRead(32, &start_time, &AcpiGbl_FADT->XPmTmrBlk);
900     CPU_GET_REG(cx_next->p_lvlx, 1);
901 
902     /*
903      * Read the end time twice.  Since it may take an arbitrary time
904      * to enter the idle state, the first read may be executed before
905      * the processor has stopped.  Doing it again provides enough
906      * margin that we are certain to have a correct value.
907      */
908     AcpiHwLowLevelRead(32, &end_time, &AcpiGbl_FADT->XPmTmrBlk);
909     AcpiHwLowLevelRead(32, &end_time, &AcpiGbl_FADT->XPmTmrBlk);
910 
911     /* Enable bus master arbitration and disable bus master wakeup. */
912     if (cx_next->type == ACPI_STATE_C3) {
913 	AcpiSetRegister(ACPI_BITREG_ARB_DISABLE, 0, ACPI_MTX_DO_NOT_LOCK);
914 	AcpiSetRegister(ACPI_BITREG_BUS_MASTER_RLD, 0, ACPI_MTX_DO_NOT_LOCK);
915     }
916 
917     /* Find the actual time asleep in microseconds, minus overhead. */
918     end_time = acpi_TimerDelta(end_time, start_time);
919     sc->cpu_prev_sleep = PM_USEC(end_time) - cx_next->trans_lat;
920     ACPI_ENABLE_IRQS();
921 }
922 
923 /* Put the CPU in C1 in a machine-dependant way. */
924 static void
925 acpi_cpu_c1()
926 {
927 #ifdef __ia64__
928     ia64_call_pal_static(PAL_HALT_LIGHT, 0, 0, 0);
929 #else
930     __asm __volatile("sti; hlt");
931 #endif
932 }
933 
934 /*
935  * Re-evaluate the _PSS and _CST objects when we are notified that they
936  * have changed.
937  *
938  * XXX Re-evaluation disabled until locking is done.
939  */
940 static void
941 acpi_cpu_notify(ACPI_HANDLE h, UINT32 notify, void *context)
942 {
943     struct acpi_cpu_softc *sc = (struct acpi_cpu_softc *)context;
944 
945     switch (notify) {
946     case ACPI_CPU_NOTIFY_PERF_STATES:
947 	device_printf(sc->cpu_dev, "Performance states changed\n");
948 	/* acpi_cpu_px_available(sc); */
949 	break;
950     case ACPI_CPU_NOTIFY_CX_STATES:
951 	device_printf(sc->cpu_dev, "Cx states changed\n");
952 	/* acpi_cpu_cx_cst(sc); */
953 	break;
954     default:
955 	device_printf(sc->cpu_dev, "Unknown notify %#x\n", notify);
956 	break;
957     }
958 }
959 
960 static int
961 acpi_cpu_quirks(struct acpi_cpu_softc *sc)
962 {
963 
964     /*
965      * C3 is not supported on multiple CPUs since this would require
966      * flushing all caches which is currently too expensive.
967      */
968     if (mp_ncpus > 1)
969 	cpu_quirks |= CPU_QUIRK_NO_C3;
970 
971 #ifdef notyet
972     /* Look for various quirks of the PIIX4 part. */
973     acpi_dev = pci_find_device(PCI_VENDOR_INTEL, PCI_DEVICE_82371AB_3);
974     if (acpi_dev != NULL) {
975 	switch (pci_get_revid(acpi_dev)) {
976 	/*
977 	 * Disable throttling control on PIIX4 A and B-step.
978 	 * See specification changes #13 ("Manual Throttle Duty Cycle")
979 	 * and #14 ("Enabling and Disabling Manual Throttle"), plus
980 	 * erratum #5 ("STPCLK# Deassertion Time") from the January
981 	 * 2002 PIIX4 specification update.  Note that few (if any)
982 	 * mobile systems ever used this part.
983 	 */
984 	case PCI_REVISION_A_STEP:
985 	case PCI_REVISION_B_STEP:
986 	    cpu_quirks |= CPU_QUIRK_NO_THROTTLE;
987 	    /* FALLTHROUGH */
988 	/*
989 	 * Disable C3 support for all PIIX4 chipsets.  Some of these parts
990 	 * do not report the BMIDE status to the BM status register and
991 	 * others have a livelock bug if Type-F DMA is enabled.  Linux
992 	 * works around the BMIDE bug by reading the BM status directly
993 	 * but we take the simpler approach of disabling C3 for these
994 	 * parts.
995 	 *
996 	 * See erratum #18 ("C3 Power State/BMIDE and Type-F DMA
997 	 * Livelock") from the January 2002 PIIX4 specification update.
998 	 * Applies to all PIIX4 models.
999 	 */
1000 	case PCI_REVISION_4E:
1001 	case PCI_REVISION_4M:
1002 	    cpu_quirks |= CPU_QUIRK_NO_C3;
1003 	    break;
1004 	default:
1005 	    break;
1006 	}
1007     }
1008 #endif
1009 
1010     return (0);
1011 }
1012 
1013 /* Handle changes in the CPU throttling setting. */
1014 static int
1015 acpi_cpu_throttle_sysctl(SYSCTL_HANDLER_ARGS)
1016 {
1017     uint32_t	*argp;
1018     uint32_t	 arg;
1019     int		 error;
1020     ACPI_LOCK_DECL;
1021 
1022     argp = (uint32_t *)oidp->oid_arg1;
1023     arg = *argp;
1024     error = sysctl_handle_int(oidp, &arg, 0, req);
1025 
1026     /* Error or no new value */
1027     if (error != 0 || req->newptr == NULL)
1028 	return (error);
1029     if (arg < 1 || arg > cpu_throttle_max)
1030 	return (EINVAL);
1031 
1032     /* If throttling changed, notify the BIOS of the new rate. */
1033     ACPI_LOCK;
1034     if (*argp != arg) {
1035 	*argp = arg;
1036 	acpi_cpu_throttle_set(arg);
1037     }
1038     ACPI_UNLOCK;
1039 
1040     return (0);
1041 }
1042 
1043 static int
1044 acpi_cpu_usage_sysctl(SYSCTL_HANDLER_ARGS)
1045 {
1046     struct sbuf	 sb;
1047     char	 buf[128];
1048     int		 i;
1049     uintmax_t	 fract, sum, whole;
1050 
1051     sum = 0;
1052     for (i = 0; i < cpu_cx_count; i++)
1053 	sum += cpu_cx_stats[i];
1054     sbuf_new(&sb, buf, sizeof(buf), SBUF_FIXEDLEN);
1055     for (i = 0; i < cpu_cx_count; i++) {
1056 	if (sum > 0) {
1057 	    whole = (uintmax_t)cpu_cx_stats[i] * 100;
1058 	    fract = (whole % sum) * 100;
1059 	    sbuf_printf(&sb, "%u.%02u%% ", (u_int)(whole / sum),
1060 		(u_int)(fract / sum));
1061 	} else
1062 	    sbuf_printf(&sb, "0%% ");
1063     }
1064     sbuf_trim(&sb);
1065     sbuf_finish(&sb);
1066     sysctl_handle_string(oidp, sbuf_data(&sb), sbuf_len(&sb), req);
1067     sbuf_delete(&sb);
1068 
1069     return (0);
1070 }
1071 
1072 static int
1073 acpi_cpu_cx_lowest_sysctl(SYSCTL_HANDLER_ARGS)
1074 {
1075     struct	 acpi_cpu_softc *sc;
1076     char	 state[8];
1077     int		 val, error, i;
1078 
1079     sc = device_get_softc(cpu_devices[0]);
1080     snprintf(state, sizeof(state), "C%d", cpu_cx_lowest + 1);
1081     error = sysctl_handle_string(oidp, state, sizeof(state), req);
1082     if (error != 0 || req->newptr == NULL)
1083 	return (error);
1084     if (strlen(state) < 2 || toupper(state[0]) != 'C')
1085 	return (EINVAL);
1086     val = (int) strtol(state + 1, NULL, 10) - 1;
1087     if (val < 0 || val > cpu_cx_count - 1)
1088 	return (EINVAL);
1089 
1090     cpu_cx_lowest = val;
1091 
1092     /* If not disabling, cache the new lowest non-C3 state. */
1093     cpu_non_c3 = 0;
1094     for (i = cpu_cx_lowest; i >= 0; i--) {
1095 	if (sc->cpu_cx_states[i].type < ACPI_STATE_C3) {
1096 	    cpu_non_c3 = i;
1097 	    break;
1098 	}
1099     }
1100 
1101     /* Reset the statistics counters. */
1102     bzero(cpu_cx_stats, sizeof(cpu_cx_stats));
1103 
1104     return (0);
1105 }
1106