xref: /freebsd/sys/dev/acpica/acpi_cpu.c (revision 122abe0385259048f1dbfcf673fdd173cf26ea09)
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 ACPI_SERIAL_DECL(cpu, "ACPI CPU");
141 
142 static struct sysctl_ctx_list	acpi_cpu_sysctl_ctx;
143 static struct sysctl_oid	*acpi_cpu_sysctl_tree;
144 
145 static int	acpi_cpu_probe(device_t dev);
146 static int	acpi_cpu_attach(device_t dev);
147 static int	acpi_pcpu_get_id(uint32_t idx, uint32_t *acpi_id,
148 				 uint32_t *cpu_id);
149 static int	acpi_cpu_shutdown(device_t dev);
150 static int	acpi_cpu_throttle_probe(struct acpi_cpu_softc *sc);
151 static int	acpi_cpu_cx_probe(struct acpi_cpu_softc *sc);
152 static int	acpi_cpu_cx_cst(struct acpi_cpu_softc *sc);
153 static void	acpi_cpu_startup(void *arg);
154 static void	acpi_cpu_startup_throttling(void);
155 static void	acpi_cpu_startup_cx(void);
156 static void	acpi_cpu_throttle_set(uint32_t speed);
157 static void	acpi_cpu_idle(void);
158 static void	acpi_cpu_c1(void);
159 static void	acpi_cpu_notify(ACPI_HANDLE h, UINT32 notify, void *context);
160 static int	acpi_cpu_quirks(struct acpi_cpu_softc *sc);
161 static int	acpi_cpu_throttle_sysctl(SYSCTL_HANDLER_ARGS);
162 static int	acpi_cpu_usage_sysctl(SYSCTL_HANDLER_ARGS);
163 static int	acpi_cpu_cx_lowest_sysctl(SYSCTL_HANDLER_ARGS);
164 
165 static device_method_t acpi_cpu_methods[] = {
166     /* Device interface */
167     DEVMETHOD(device_probe,	acpi_cpu_probe),
168     DEVMETHOD(device_attach,	acpi_cpu_attach),
169     DEVMETHOD(device_shutdown,	acpi_cpu_shutdown),
170 
171     {0, 0}
172 };
173 
174 static driver_t acpi_cpu_driver = {
175     "cpu",
176     acpi_cpu_methods,
177     sizeof(struct acpi_cpu_softc),
178 };
179 
180 static devclass_t acpi_cpu_devclass;
181 DRIVER_MODULE(cpu, acpi, acpi_cpu_driver, acpi_cpu_devclass, 0, 0);
182 MODULE_DEPEND(cpu, acpi, 1, 1, 1);
183 
184 static int
185 acpi_cpu_probe(device_t dev)
186 {
187     int			   acpi_id, cpu_id, cx_count;
188     ACPI_BUFFER		   buf;
189     ACPI_HANDLE		   handle;
190     char		   msg[32];
191     ACPI_OBJECT		   *obj;
192     ACPI_STATUS		   status;
193 
194     if (acpi_disabled("cpu") || acpi_get_type(dev) != ACPI_TYPE_PROCESSOR)
195 	return (ENXIO);
196 
197     handle = acpi_get_handle(dev);
198     if (cpu_softc == NULL)
199 	cpu_softc = malloc(sizeof(struct acpi_cpu_softc *) *
200 	    (mp_maxid + 1), M_TEMP /* XXX */, M_WAITOK | M_ZERO);
201 
202     /* Get our Processor object. */
203     buf.Pointer = NULL;
204     buf.Length = ACPI_ALLOCATE_BUFFER;
205     status = AcpiEvaluateObject(handle, NULL, NULL, &buf);
206     if (ACPI_FAILURE(status)) {
207 	device_printf(dev, "probe failed to get Processor obj - %s\n",
208 		      AcpiFormatException(status));
209 	return (ENXIO);
210     }
211     obj = (ACPI_OBJECT *)buf.Pointer;
212     if (obj->Type != ACPI_TYPE_PROCESSOR) {
213 	device_printf(dev, "Processor object has bad type %d\n", obj->Type);
214 	AcpiOsFree(obj);
215 	return (ENXIO);
216     }
217 
218     /*
219      * Find the processor associated with our unit.  We could use the
220      * ProcId as a key, however, some boxes do not have the same values
221      * in their Processor object as the ProcId values in the MADT.
222      */
223     acpi_id = obj->Processor.ProcId;
224     AcpiOsFree(obj);
225     if (acpi_pcpu_get_id(device_get_unit(dev), &acpi_id, &cpu_id) != 0)
226 	return (ENXIO);
227 
228     /*
229      * Check if we already probed this processor.  We scan the bus twice
230      * so it's possible we've already seen this one.
231      */
232     if (cpu_softc[cpu_id] != NULL)
233 	return (ENXIO);
234 
235     /* Get a count of Cx states for our device string. */
236     cx_count = 0;
237     buf.Pointer = NULL;
238     buf.Length = ACPI_ALLOCATE_BUFFER;
239     status = AcpiEvaluateObject(handle, "_CST", NULL, &buf);
240     if (ACPI_SUCCESS(status)) {
241 	obj = (ACPI_OBJECT *)buf.Pointer;
242 	if (ACPI_PKG_VALID(obj, 2))
243 	    acpi_PkgInt32(obj, 0, &cx_count);
244 	AcpiOsFree(obj);
245     } else {
246 	if (AcpiGbl_FADT->Plvl2Lat <= 100)
247 	    cx_count++;
248 	if (AcpiGbl_FADT->Plvl3Lat <= 1000)
249 	    cx_count++;
250 	if (cx_count > 0)
251 	    cx_count++;
252     }
253     if (cx_count > 0)
254 	snprintf(msg, sizeof(msg), "ACPI CPU (%d Cx states)", cx_count);
255     else
256 	strlcpy(msg, "ACPI CPU", sizeof(msg));
257     device_set_desc_copy(dev, msg);
258 
259     /* Mark this processor as in-use and save our derived id for attach. */
260     cpu_softc[cpu_id] = (void *)1;
261     acpi_set_magic(dev, cpu_id);
262 
263     return (0);
264 }
265 
266 static int
267 acpi_cpu_attach(device_t dev)
268 {
269     ACPI_BUFFER		   buf;
270     ACPI_OBJECT		   *obj;
271     struct acpi_cpu_softc *sc;
272     struct acpi_softc	  *acpi_sc;
273     ACPI_STATUS		   status;
274     int			   thr_ret, cx_ret;
275 
276     ACPI_FUNCTION_TRACE((char *)(uintptr_t)__func__);
277 
278     sc = device_get_softc(dev);
279     sc->cpu_dev = dev;
280     sc->cpu_handle = acpi_get_handle(dev);
281     cpu_softc[acpi_get_magic(dev)] = sc;
282 
283     buf.Pointer = NULL;
284     buf.Length = ACPI_ALLOCATE_BUFFER;
285     status = AcpiEvaluateObject(sc->cpu_handle, NULL, NULL, &buf);
286     if (ACPI_FAILURE(status)) {
287 	device_printf(dev, "attach failed to get Processor obj - %s\n",
288 		      AcpiFormatException(status));
289 	return (ENXIO);
290     }
291     obj = (ACPI_OBJECT *)buf.Pointer;
292     sc->cpu_p_blk = obj->Processor.PblkAddress;
293     sc->cpu_p_blk_len = obj->Processor.PblkLength;
294     sc->acpi_id = obj->Processor.ProcId;
295     AcpiOsFree(obj);
296     ACPI_DEBUG_PRINT((ACPI_DB_INFO, "acpi_cpu%d: P_BLK at %#x/%d\n",
297 		     device_get_unit(dev), sc->cpu_p_blk, sc->cpu_p_blk_len));
298 
299     acpi_sc = acpi_device_get_parent_softc(dev);
300     sysctl_ctx_init(&acpi_cpu_sysctl_ctx);
301     acpi_cpu_sysctl_tree = SYSCTL_ADD_NODE(&acpi_cpu_sysctl_ctx,
302 				SYSCTL_CHILDREN(acpi_sc->acpi_sysctl_tree),
303 				OID_AUTO, "cpu", CTLFLAG_RD, 0, "");
304 
305     /* If this is the first device probed, check for quirks. */
306     if (device_get_unit(dev) == 0)
307 	acpi_cpu_quirks(sc);
308 
309     /*
310      * Probe for throttling and Cx state support.
311      * If none of these is present, free up unused resources.
312      */
313     thr_ret = acpi_cpu_throttle_probe(sc);
314     cx_ret = acpi_cpu_cx_probe(sc);
315     if (thr_ret == 0 || cx_ret == 0) {
316 	status = AcpiInstallNotifyHandler(sc->cpu_handle, ACPI_DEVICE_NOTIFY,
317 					  acpi_cpu_notify, sc);
318 	if (device_get_unit(dev) == 0)
319 	    AcpiOsQueueForExecution(OSD_PRIORITY_LO, acpi_cpu_startup, NULL);
320     } else {
321 	sysctl_ctx_free(&acpi_cpu_sysctl_ctx);
322     }
323 
324     return_VALUE (0);
325 }
326 
327 /*
328  * Find the nth present CPU and return its pc_cpuid as well as set the
329  * pc_acpi_id from the most reliable source.
330  */
331 static int
332 acpi_pcpu_get_id(uint32_t idx, uint32_t *acpi_id, uint32_t *cpu_id)
333 {
334     struct pcpu	*pcpu_data;
335     uint32_t	 i;
336 
337     KASSERT(acpi_id != NULL, ("Null acpi_id"));
338     KASSERT(cpu_id != NULL, ("Null cpu_id"));
339     for (i = 0; i <= mp_maxid; i++) {
340 	if (CPU_ABSENT(i))
341 	    continue;
342 	pcpu_data = pcpu_find(i);
343 	KASSERT(pcpu_data != NULL, ("no pcpu data for %d", i));
344 	if (idx-- == 0) {
345 	    /*
346 	     * If pc_acpi_id was not initialized (e.g., a non-APIC UP box)
347 	     * override it with the value from the ASL.  Otherwise, if the
348 	     * two don't match, prefer the MADT-derived value.  Finally,
349 	     * return the pc_cpuid to reference this processor.
350 	     */
351 	    if (pcpu_data->pc_acpi_id == 0xffffffff)
352 		 pcpu_data->pc_acpi_id = *acpi_id;
353 	    else if (pcpu_data->pc_acpi_id != *acpi_id)
354 		*acpi_id = pcpu_data->pc_acpi_id;
355 	    *cpu_id = pcpu_data->pc_cpuid;
356 	    return (0);
357 	}
358     }
359 
360     return (ESRCH);
361 }
362 
363 static int
364 acpi_cpu_shutdown(device_t dev)
365 {
366     ACPI_FUNCTION_TRACE((char *)(uintptr_t)__func__);
367 
368     /* Disable any entry to the idle function. */
369     cpu_cx_count = 0;
370 
371     /* Signal and wait for all processors to exit acpi_cpu_idle(). */
372     smp_rendezvous(NULL, NULL, NULL, NULL);
373 
374     return_VALUE (0);
375 }
376 
377 static int
378 acpi_cpu_throttle_probe(struct acpi_cpu_softc *sc)
379 {
380     uint32_t		 duty_end;
381     ACPI_BUFFER		 buf;
382     ACPI_OBJECT		 obj;
383     ACPI_GENERIC_ADDRESS gas;
384     ACPI_STATUS		 status;
385 
386     ACPI_FUNCTION_TRACE((char *)(uintptr_t)__func__);
387 
388     /* Get throttling parameters from the FADT.  0 means not supported. */
389     if (device_get_unit(sc->cpu_dev) == 0) {
390 	cpu_smi_cmd = AcpiGbl_FADT->SmiCmd;
391 	cpu_pstate_cnt = AcpiGbl_FADT->PstateCnt;
392 	cpu_cst_cnt = AcpiGbl_FADT->CstCnt;
393 	cpu_duty_offset = AcpiGbl_FADT->DutyOffset;
394 	cpu_duty_width = AcpiGbl_FADT->DutyWidth;
395     }
396     if (cpu_duty_width == 0 || (cpu_quirks & CPU_QUIRK_NO_THROTTLE) != 0)
397 	return (ENXIO);
398 
399     /* Validate the duty offset/width. */
400     duty_end = cpu_duty_offset + cpu_duty_width - 1;
401     if (duty_end > 31) {
402 	device_printf(sc->cpu_dev, "CLK_VAL field overflows P_CNT register\n");
403 	return (ENXIO);
404     }
405     if (cpu_duty_offset <= 4 && duty_end >= 4) {
406 	device_printf(sc->cpu_dev, "CLK_VAL field overlaps THT_EN bit\n");
407 	return (ENXIO);
408     }
409 
410     /*
411      * If not present, fall back to using the processor's P_BLK to find
412      * the P_CNT register.
413      *
414      * Note that some systems seem to duplicate the P_BLK pointer
415      * across multiple CPUs, so not getting the resource is not fatal.
416      */
417     buf.Pointer = &obj;
418     buf.Length = sizeof(obj);
419     status = AcpiEvaluateObject(sc->cpu_handle, "_PTC", NULL, &buf);
420     if (ACPI_SUCCESS(status)) {
421 	if (obj.Buffer.Length < sizeof(ACPI_GENERIC_ADDRESS) + 3) {
422 	    device_printf(sc->cpu_dev, "_PTC buffer too small\n");
423 	    return (ENXIO);
424 	}
425 	memcpy(&gas, obj.Buffer.Pointer + 3, sizeof(gas));
426 	sc->cpu_p_cnt = acpi_bus_alloc_gas(sc->cpu_dev, &cpu_rid, &gas);
427 	if (sc->cpu_p_cnt != NULL) {
428 	    ACPI_DEBUG_PRINT((ACPI_DB_INFO, "acpi_cpu%d: P_CNT from _PTC\n",
429 			     device_get_unit(sc->cpu_dev)));
430 	}
431     }
432 
433     /* If _PTC not present or other failure, try the P_BLK. */
434     if (sc->cpu_p_cnt == NULL) {
435 	/*
436 	 * The spec says P_BLK must be 6 bytes long.  However, some
437 	 * systems use it to indicate a fractional set of features
438 	 * present so we take anything >= 4.
439 	 */
440 	if (sc->cpu_p_blk_len < 4)
441 	    return (ENXIO);
442 	gas.Address = sc->cpu_p_blk;
443 	gas.AddressSpaceId = ACPI_ADR_SPACE_SYSTEM_IO;
444 	gas.RegisterBitWidth = 32;
445 	sc->cpu_p_cnt = acpi_bus_alloc_gas(sc->cpu_dev, &cpu_rid, &gas);
446 	if (sc->cpu_p_cnt != NULL) {
447 	    ACPI_DEBUG_PRINT((ACPI_DB_INFO, "acpi_cpu%d: P_CNT from P_BLK\n",
448 			     device_get_unit(sc->cpu_dev)));
449 	} else {
450 	    device_printf(sc->cpu_dev, "Failed to attach throttling P_CNT\n");
451 	    return (ENXIO);
452 	}
453     }
454     cpu_rid++;
455 
456     return (0);
457 }
458 
459 static int
460 acpi_cpu_cx_probe(struct acpi_cpu_softc *sc)
461 {
462     ACPI_GENERIC_ADDRESS gas;
463     struct acpi_cx	*cx_ptr;
464     int			 error;
465 
466     ACPI_FUNCTION_TRACE((char *)(uintptr_t)__func__);
467 
468     /* Bus mastering arbitration control is needed for C3. */
469     if (AcpiGbl_FADT->V1_Pm2CntBlk == 0 || AcpiGbl_FADT->Pm2CntLen == 0) {
470 	cpu_quirks |= CPU_QUIRK_NO_C3;
471 	ACPI_DEBUG_PRINT((ACPI_DB_INFO,
472 			 "acpi_cpu%d: No BM control, C3 disabled\n",
473 			 device_get_unit(sc->cpu_dev)));
474     }
475 
476     /*
477      * First, check for the ACPI 2.0 _CST sleep states object.
478      * If not usable, fall back to the P_BLK's P_LVL2 and P_LVL3.
479      */
480     sc->cpu_cx_count = 0;
481     error = acpi_cpu_cx_cst(sc);
482     if (error != 0) {
483 	cx_ptr = sc->cpu_cx_states;
484 
485 	/* C1 has been required since just after ACPI 1.0 */
486 	cx_ptr->type = ACPI_STATE_C1;
487 	cx_ptr->trans_lat = 0;
488 	cpu_non_c3 = 0;
489 	cx_ptr++;
490 	sc->cpu_cx_count++;
491 
492 	/*
493 	 * The spec says P_BLK must be 6 bytes long.  However, some systems
494 	 * use it to indicate a fractional set of features present so we
495 	 * take 5 as C2.  Some may also have a value of 7 to indicate
496 	 * another C3 but most use _CST for this (as required) and having
497 	 * "only" C1-C3 is not a hardship.
498 	 */
499 	if (sc->cpu_p_blk_len < 5)
500 	    goto done;
501 
502 	/* Validate and allocate resources for C2 (P_LVL2). */
503 	gas.AddressSpaceId = ACPI_ADR_SPACE_SYSTEM_IO;
504 	gas.RegisterBitWidth = 8;
505 	if (AcpiGbl_FADT->Plvl2Lat <= 100) {
506 	    gas.Address = sc->cpu_p_blk + 4;
507 	    cx_ptr->p_lvlx = acpi_bus_alloc_gas(sc->cpu_dev, &cpu_rid, &gas);
508 	    if (cx_ptr->p_lvlx != NULL) {
509 		cpu_rid++;
510 		cx_ptr->type = ACPI_STATE_C2;
511 		cx_ptr->trans_lat = AcpiGbl_FADT->Plvl2Lat;
512 		cpu_non_c3 = 1;
513 		cx_ptr++;
514 		sc->cpu_cx_count++;
515 	    }
516 	}
517 	if (sc->cpu_p_blk_len < 6)
518 	    goto done;
519 
520 	/* Validate and allocate resources for C3 (P_LVL3). */
521 	if (AcpiGbl_FADT->Plvl3Lat <= 1000 &&
522 	    (cpu_quirks & CPU_QUIRK_NO_C3) == 0) {
523 
524 	    gas.Address = sc->cpu_p_blk + 5;
525 	    cx_ptr->p_lvlx = acpi_bus_alloc_gas(sc->cpu_dev, &cpu_rid, &gas);
526 	    if (cx_ptr->p_lvlx != NULL) {
527 		cpu_rid++;
528 		cx_ptr->type = ACPI_STATE_C3;
529 		cx_ptr->trans_lat = AcpiGbl_FADT->Plvl3Lat;
530 		cx_ptr++;
531 		sc->cpu_cx_count++;
532 	    }
533 	}
534     }
535 
536 done:
537     /* If no valid registers were found, don't attach. */
538     if (sc->cpu_cx_count == 0)
539 	return (ENXIO);
540 
541     /* Use initial sleep value of 1 sec. to start with lowest idle state. */
542     sc->cpu_prev_sleep = 1000000;
543 
544     return (0);
545 }
546 
547 /*
548  * Parse a _CST package and set up its Cx states.  Since the _CST object
549  * can change dynamically, our notify handler may call this function
550  * to clean up and probe the new _CST package.
551  */
552 static int
553 acpi_cpu_cx_cst(struct acpi_cpu_softc *sc)
554 {
555     struct	 acpi_cx *cx_ptr;
556     ACPI_STATUS	 status;
557     ACPI_BUFFER	 buf;
558     ACPI_OBJECT	*top;
559     ACPI_OBJECT	*pkg;
560     uint32_t	 count;
561     int		 i;
562 
563     ACPI_FUNCTION_TRACE((char *)(uintptr_t)__func__);
564 
565     buf.Pointer = NULL;
566     buf.Length = ACPI_ALLOCATE_BUFFER;
567     status = AcpiEvaluateObject(sc->cpu_handle, "_CST", NULL, &buf);
568     if (ACPI_FAILURE(status))
569 	return (ENXIO);
570 
571     /* _CST is a package with a count and at least one Cx package. */
572     top = (ACPI_OBJECT *)buf.Pointer;
573     if (!ACPI_PKG_VALID(top, 2) || acpi_PkgInt32(top, 0, &count) != 0) {
574 	device_printf(sc->cpu_dev, "Invalid _CST package\n");
575 	AcpiOsFree(buf.Pointer);
576 	return (ENXIO);
577     }
578     if (count != top->Package.Count - 1) {
579 	device_printf(sc->cpu_dev, "Invalid _CST state count (%d != %d)\n",
580 	       count, top->Package.Count - 1);
581 	count = top->Package.Count - 1;
582     }
583     if (count > MAX_CX_STATES) {
584 	device_printf(sc->cpu_dev, "_CST has too many states (%d)\n", count);
585 	count = MAX_CX_STATES;
586     }
587 
588     /* Set up all valid states. */
589     sc->cpu_cx_count = 0;
590     cx_ptr = sc->cpu_cx_states;
591     for (i = 0; i < count; i++) {
592 	pkg = &top->Package.Elements[i + 1];
593 	if (!ACPI_PKG_VALID(pkg, 4) ||
594 	    acpi_PkgInt32(pkg, 1, &cx_ptr->type) != 0 ||
595 	    acpi_PkgInt32(pkg, 2, &cx_ptr->trans_lat) != 0 ||
596 	    acpi_PkgInt32(pkg, 3, &cx_ptr->power) != 0) {
597 
598 	    device_printf(sc->cpu_dev, "Skipping invalid Cx state package\n");
599 	    continue;
600 	}
601 
602 	/* Validate the state to see if we should use it. */
603 	switch (cx_ptr->type) {
604 	case ACPI_STATE_C1:
605 	    cpu_non_c3 = i;
606 	    cx_ptr++;
607 	    sc->cpu_cx_count++;
608 	    continue;
609 	case ACPI_STATE_C2:
610 	    if (cx_ptr->trans_lat > 100) {
611 		ACPI_DEBUG_PRINT((ACPI_DB_INFO,
612 				 "acpi_cpu%d: C2[%d] not available.\n",
613 				 device_get_unit(sc->cpu_dev), i));
614 		continue;
615 	    }
616 	    cpu_non_c3 = i;
617 	    break;
618 	case ACPI_STATE_C3:
619 	default:
620 	    if (cx_ptr->trans_lat > 1000 ||
621 		(cpu_quirks & CPU_QUIRK_NO_C3) != 0) {
622 
623 		ACPI_DEBUG_PRINT((ACPI_DB_INFO,
624 				 "acpi_cpu%d: C3[%d] not available.\n",
625 				 device_get_unit(sc->cpu_dev), i));
626 		continue;
627 	    }
628 	    break;
629 	}
630 
631 #ifdef notyet
632 	/* Free up any previous register. */
633 	if (cx_ptr->p_lvlx != NULL) {
634 	    bus_release_resource(sc->cpu_dev, 0, 0, cx_ptr->p_lvlx);
635 	    cx_ptr->p_lvlx = NULL;
636 	}
637 #endif
638 
639 	/* Allocate the control register for C2 or C3. */
640 	acpi_PkgGas(sc->cpu_dev, pkg, 0, &cpu_rid, &cx_ptr->p_lvlx);
641 	if (cx_ptr->p_lvlx != NULL) {
642 	    cpu_rid++;
643 	    ACPI_DEBUG_PRINT((ACPI_DB_INFO,
644 			     "acpi_cpu%d: Got C%d - %d latency\n",
645 			     device_get_unit(sc->cpu_dev), cx_ptr->type,
646 			     cx_ptr->trans_lat));
647 	    cx_ptr++;
648 	    sc->cpu_cx_count++;
649 	}
650     }
651     AcpiOsFree(buf.Pointer);
652 
653     return (0);
654 }
655 
656 /*
657  * Call this *after* all CPUs have been attached.
658  */
659 static void
660 acpi_cpu_startup(void *arg)
661 {
662     struct acpi_cpu_softc *sc;
663     int count, i;
664 
665     /* Get set of CPU devices */
666     devclass_get_devices(acpi_cpu_devclass, &cpu_devices, &cpu_ndevices);
667 
668     /*
669      * Make sure all the processors' Cx counts match.  We should probably
670      * also check the contents of each.  However, no known systems have
671      * non-matching Cx counts so we'll deal with this later.
672      */
673     count = MAX_CX_STATES;
674     for (i = 0; i < cpu_ndevices; i++) {
675 	sc = device_get_softc(cpu_devices[i]);
676 	count = min(sc->cpu_cx_count, count);
677     }
678     cpu_cx_count = count;
679 
680     /* Perform throttling and Cx final initialization. */
681     sc = device_get_softc(cpu_devices[0]);
682     if (sc->cpu_p_cnt != NULL)
683 	acpi_cpu_startup_throttling();
684     if (cpu_cx_count > 0)
685 	acpi_cpu_startup_cx();
686 }
687 
688 /*
689  * Takes the ACPI lock to avoid fighting anyone over the SMI command
690  * port.
691  */
692 static void
693 acpi_cpu_startup_throttling()
694 {
695 
696     /* Initialise throttling states */
697     cpu_throttle_max = CPU_MAX_SPEED;
698     cpu_throttle_state = CPU_MAX_SPEED;
699 
700     SYSCTL_ADD_INT(&acpi_cpu_sysctl_ctx,
701 		   SYSCTL_CHILDREN(acpi_cpu_sysctl_tree),
702 		   OID_AUTO, "throttle_max", CTLFLAG_RD,
703 		   &cpu_throttle_max, 0, "maximum CPU speed");
704     SYSCTL_ADD_PROC(&acpi_cpu_sysctl_ctx,
705 		    SYSCTL_CHILDREN(acpi_cpu_sysctl_tree),
706 		    OID_AUTO, "throttle_state",
707 		    CTLTYPE_INT | CTLFLAG_RW, &cpu_throttle_state,
708 		    0, acpi_cpu_throttle_sysctl, "I", "current CPU speed");
709 
710     /* If ACPI 2.0+, signal platform that we are taking over throttling. */
711     if (cpu_pstate_cnt != 0) {
712 	ACPI_LOCK(acpi);
713 	AcpiOsWritePort(cpu_smi_cmd, cpu_pstate_cnt, 8);
714 	ACPI_UNLOCK(acpi);
715     }
716 
717     /* Set initial speed to maximum. */
718     ACPI_SERIAL_BEGIN(cpu);
719     acpi_cpu_throttle_set(cpu_throttle_max);
720     ACPI_SERIAL_END(cpu);
721 
722     printf("acpi_cpu: throttling enabled, %d steps (100%% to %d.%d%%), "
723 	   "currently %d.%d%%\n", CPU_MAX_SPEED, CPU_SPEED_PRINTABLE(1),
724 	   CPU_SPEED_PRINTABLE(cpu_throttle_state));
725 }
726 
727 static void
728 acpi_cpu_startup_cx()
729 {
730     struct acpi_cpu_softc *sc;
731     struct sbuf		 sb;
732     int i;
733 
734     sc = device_get_softc(cpu_devices[0]);
735     sbuf_new(&sb, cpu_cx_supported, sizeof(cpu_cx_supported), SBUF_FIXEDLEN);
736     for (i = 0; i < cpu_cx_count; i++)
737 	sbuf_printf(&sb, "C%d/%d ", i + 1, sc->cpu_cx_states[i].trans_lat);
738     sbuf_trim(&sb);
739     sbuf_finish(&sb);
740     SYSCTL_ADD_STRING(&acpi_cpu_sysctl_ctx,
741 		      SYSCTL_CHILDREN(acpi_cpu_sysctl_tree),
742 		      OID_AUTO, "cx_supported", CTLFLAG_RD, cpu_cx_supported,
743 		      0, "Cx/microsecond values for supported Cx states");
744     SYSCTL_ADD_PROC(&acpi_cpu_sysctl_ctx,
745 		    SYSCTL_CHILDREN(acpi_cpu_sysctl_tree),
746 		    OID_AUTO, "cx_lowest", CTLTYPE_STRING | CTLFLAG_RW,
747 		    NULL, 0, acpi_cpu_cx_lowest_sysctl, "A",
748 		    "lowest Cx sleep state to use");
749     SYSCTL_ADD_PROC(&acpi_cpu_sysctl_ctx,
750 		    SYSCTL_CHILDREN(acpi_cpu_sysctl_tree),
751 		    OID_AUTO, "cx_usage", CTLTYPE_STRING | CTLFLAG_RD,
752 		    NULL, 0, acpi_cpu_usage_sysctl, "A",
753 		    "percent usage for each Cx state");
754 
755 #ifdef notyet
756     /* Signal platform that we can handle _CST notification. */
757     if (cpu_cst_cnt != 0) {
758 	ACPI_LOCK(acpi);
759 	AcpiOsWritePort(cpu_smi_cmd, cpu_cst_cnt, 8);
760 	ACPI_UNLOCK(acpi);
761     }
762 #endif
763 
764     /* Take over idling from cpu_idle_default(). */
765     cpu_idle_hook = acpi_cpu_idle;
766 }
767 
768 /*
769  * Set CPUs to the new state.
770  *
771  * Must be called with the ACPI lock held.
772  */
773 static void
774 acpi_cpu_throttle_set(uint32_t speed)
775 {
776     struct acpi_cpu_softc	*sc;
777     int				i;
778     uint32_t			p_cnt, clk_val;
779 
780     ACPI_SERIAL_ASSERT(cpu);
781 
782     /* Iterate over processors */
783     for (i = 0; i < cpu_ndevices; i++) {
784 	sc = device_get_softc(cpu_devices[i]);
785 	if (sc->cpu_p_cnt == NULL)
786 	    continue;
787 
788 	/* Get the current P_CNT value and disable throttling */
789 	p_cnt = CPU_GET_REG(sc->cpu_p_cnt, 4);
790 	p_cnt &= ~CPU_P_CNT_THT_EN;
791 	CPU_SET_REG(sc->cpu_p_cnt, 4, p_cnt);
792 
793 	/* If we're at maximum speed, that's all */
794 	if (speed < CPU_MAX_SPEED) {
795 	    /* Mask the old CLK_VAL off and or-in the new value */
796 	    clk_val = (CPU_MAX_SPEED - 1) << cpu_duty_offset;
797 	    p_cnt &= ~clk_val;
798 	    p_cnt |= (speed << cpu_duty_offset);
799 
800 	    /* Write the new P_CNT value and then enable throttling */
801 	    CPU_SET_REG(sc->cpu_p_cnt, 4, p_cnt);
802 	    p_cnt |= CPU_P_CNT_THT_EN;
803 	    CPU_SET_REG(sc->cpu_p_cnt, 4, p_cnt);
804 	}
805 	ACPI_VPRINT(sc->cpu_dev, acpi_device_get_parent_softc(sc->cpu_dev),
806 		    "set speed to %d.%d%%\n", CPU_SPEED_PRINTABLE(speed));
807     }
808     cpu_throttle_state = speed;
809 }
810 
811 /*
812  * Idle the CPU in the lowest state possible.  This function is called with
813  * interrupts disabled.  Note that once it re-enables interrupts, a task
814  * switch can occur so do not access shared data (i.e. the softc) after
815  * interrupts are re-enabled.
816  */
817 static void
818 acpi_cpu_idle()
819 {
820     struct	acpi_cpu_softc *sc;
821     struct	acpi_cx *cx_next;
822     uint32_t	start_time, end_time;
823     int		bm_active, cx_next_idx, i;
824 
825     /* If disabled, return immediately. */
826     if (cpu_cx_count == 0) {
827 	ACPI_ENABLE_IRQS();
828 	return;
829     }
830 
831     /*
832      * Look up our CPU id to get our softc.  If it's NULL, we'll use C1
833      * since there is no ACPI processor object for this CPU.  This occurs
834      * for logical CPUs in the HTT case.
835      */
836     sc = cpu_softc[PCPU_GET(cpuid)];
837     if (sc == NULL) {
838 	acpi_cpu_c1();
839 	return;
840     }
841 
842     /*
843      * If we slept 100 us or more, use the lowest Cx state.  Otherwise,
844      * find the lowest state that has a latency less than or equal to
845      * the length of our last sleep.
846      */
847     cx_next_idx = cpu_cx_lowest;
848     if (sc->cpu_prev_sleep < 100)
849 	for (i = cpu_cx_lowest; i >= 0; i--)
850 	    if (sc->cpu_cx_states[i].trans_lat <= sc->cpu_prev_sleep) {
851 		cx_next_idx = i;
852 		break;
853 	    }
854 
855     /*
856      * Check for bus master activity.  If there was activity, clear
857      * the bit and use the lowest non-C3 state.  Note that the USB
858      * driver polling for new devices keeps this bit set all the
859      * time if USB is loaded.
860      */
861     AcpiGetRegister(ACPI_BITREG_BUS_MASTER_STATUS, &bm_active,
862 		    ACPI_MTX_DO_NOT_LOCK);
863     if (bm_active != 0) {
864 	AcpiSetRegister(ACPI_BITREG_BUS_MASTER_STATUS, 1,
865 			ACPI_MTX_DO_NOT_LOCK);
866 	cx_next_idx = min(cx_next_idx, cpu_non_c3);
867     }
868 
869     /* Select the next state and update statistics. */
870     cx_next = &sc->cpu_cx_states[cx_next_idx];
871     cpu_cx_stats[cx_next_idx]++;
872     KASSERT(cx_next->type != ACPI_STATE_C0, ("acpi_cpu_idle: C0 sleep"));
873 
874     /*
875      * Execute HLT (or equivalent) and wait for an interrupt.  We can't
876      * calculate the time spent in C1 since the place we wake up is an
877      * ISR.  Assume we slept one quantum and return.
878      */
879     if (cx_next->type == ACPI_STATE_C1) {
880 	sc->cpu_prev_sleep = 1000000 / hz;
881 	acpi_cpu_c1();
882 	return;
883     }
884 
885     /* For C3, disable bus master arbitration and enable bus master wake. */
886     if (cx_next->type == ACPI_STATE_C3) {
887 	AcpiSetRegister(ACPI_BITREG_ARB_DISABLE, 1, ACPI_MTX_DO_NOT_LOCK);
888 	AcpiSetRegister(ACPI_BITREG_BUS_MASTER_RLD, 1, ACPI_MTX_DO_NOT_LOCK);
889     }
890 
891     /*
892      * Read from P_LVLx to enter C2(+), checking time spent asleep.
893      * Use the ACPI timer for measuring sleep time.  Since we need to
894      * get the time very close to the CPU start/stop clock logic, this
895      * is the only reliable time source.
896      */
897     AcpiHwLowLevelRead(32, &start_time, &AcpiGbl_FADT->XPmTmrBlk);
898     CPU_GET_REG(cx_next->p_lvlx, 1);
899 
900     /*
901      * Read the end time twice.  Since it may take an arbitrary time
902      * to enter the idle state, the first read may be executed before
903      * the processor has stopped.  Doing it again provides enough
904      * margin that we are certain to have a correct value.
905      */
906     AcpiHwLowLevelRead(32, &end_time, &AcpiGbl_FADT->XPmTmrBlk);
907     AcpiHwLowLevelRead(32, &end_time, &AcpiGbl_FADT->XPmTmrBlk);
908 
909     /* Enable bus master arbitration and disable bus master wakeup. */
910     if (cx_next->type == ACPI_STATE_C3) {
911 	AcpiSetRegister(ACPI_BITREG_ARB_DISABLE, 0, ACPI_MTX_DO_NOT_LOCK);
912 	AcpiSetRegister(ACPI_BITREG_BUS_MASTER_RLD, 0, ACPI_MTX_DO_NOT_LOCK);
913     }
914 
915     /* Find the actual time asleep in microseconds, minus overhead. */
916     end_time = acpi_TimerDelta(end_time, start_time);
917     sc->cpu_prev_sleep = PM_USEC(end_time) - cx_next->trans_lat;
918     ACPI_ENABLE_IRQS();
919 }
920 
921 /* Put the CPU in C1 in a machine-dependant way. */
922 static void
923 acpi_cpu_c1()
924 {
925 #ifdef __ia64__
926     ia64_call_pal_static(PAL_HALT_LIGHT, 0, 0, 0);
927 #else
928     __asm __volatile("sti; hlt");
929 #endif
930 }
931 
932 /*
933  * Re-evaluate the _PSS and _CST objects when we are notified that they
934  * have changed.
935  *
936  * XXX Re-evaluation disabled until locking is done.
937  */
938 static void
939 acpi_cpu_notify(ACPI_HANDLE h, UINT32 notify, void *context)
940 {
941     struct acpi_cpu_softc *sc = (struct acpi_cpu_softc *)context;
942 
943     switch (notify) {
944     case ACPI_CPU_NOTIFY_PERF_STATES:
945 	device_printf(sc->cpu_dev, "Performance states changed\n");
946 	/* acpi_cpu_px_available(sc); */
947 	break;
948     case ACPI_CPU_NOTIFY_CX_STATES:
949 	device_printf(sc->cpu_dev, "Cx states changed\n");
950 	/* acpi_cpu_cx_cst(sc); */
951 	break;
952     default:
953 	device_printf(sc->cpu_dev, "Unknown notify %#x\n", notify);
954 	break;
955     }
956 }
957 
958 static int
959 acpi_cpu_quirks(struct acpi_cpu_softc *sc)
960 {
961 
962     /*
963      * C3 is not supported on multiple CPUs since this would require
964      * flushing all caches which is currently too expensive.
965      */
966     if (mp_ncpus > 1)
967 	cpu_quirks |= CPU_QUIRK_NO_C3;
968 
969 #ifdef notyet
970     /* Look for various quirks of the PIIX4 part. */
971     acpi_dev = pci_find_device(PCI_VENDOR_INTEL, PCI_DEVICE_82371AB_3);
972     if (acpi_dev != NULL) {
973 	switch (pci_get_revid(acpi_dev)) {
974 	/*
975 	 * Disable throttling control on PIIX4 A and B-step.
976 	 * See specification changes #13 ("Manual Throttle Duty Cycle")
977 	 * and #14 ("Enabling and Disabling Manual Throttle"), plus
978 	 * erratum #5 ("STPCLK# Deassertion Time") from the January
979 	 * 2002 PIIX4 specification update.  Note that few (if any)
980 	 * mobile systems ever used this part.
981 	 */
982 	case PCI_REVISION_A_STEP:
983 	case PCI_REVISION_B_STEP:
984 	    cpu_quirks |= CPU_QUIRK_NO_THROTTLE;
985 	    /* FALLTHROUGH */
986 	/*
987 	 * Disable C3 support for all PIIX4 chipsets.  Some of these parts
988 	 * do not report the BMIDE status to the BM status register and
989 	 * others have a livelock bug if Type-F DMA is enabled.  Linux
990 	 * works around the BMIDE bug by reading the BM status directly
991 	 * but we take the simpler approach of disabling C3 for these
992 	 * parts.
993 	 *
994 	 * See erratum #18 ("C3 Power State/BMIDE and Type-F DMA
995 	 * Livelock") from the January 2002 PIIX4 specification update.
996 	 * Applies to all PIIX4 models.
997 	 */
998 	case PCI_REVISION_4E:
999 	case PCI_REVISION_4M:
1000 	    cpu_quirks |= CPU_QUIRK_NO_C3;
1001 	    break;
1002 	default:
1003 	    break;
1004 	}
1005     }
1006 #endif
1007 
1008     return (0);
1009 }
1010 
1011 /* Handle changes in the CPU throttling setting. */
1012 static int
1013 acpi_cpu_throttle_sysctl(SYSCTL_HANDLER_ARGS)
1014 {
1015     uint32_t	*argp;
1016     uint32_t	 arg;
1017     int		 error;
1018 
1019     argp = (uint32_t *)oidp->oid_arg1;
1020     arg = *argp;
1021     error = sysctl_handle_int(oidp, &arg, 0, req);
1022 
1023     /* Error or no new value */
1024     if (error != 0 || req->newptr == NULL)
1025 	return (error);
1026     if (arg < 1 || arg > cpu_throttle_max)
1027 	return (EINVAL);
1028 
1029     /* If throttling changed, notify the BIOS of the new rate. */
1030     ACPI_SERIAL_BEGIN(cpu);
1031     if (*argp != arg) {
1032 	*argp = arg;
1033 	acpi_cpu_throttle_set(arg);
1034     }
1035     ACPI_SERIAL_END(cpu);
1036 
1037     return (0);
1038 }
1039 
1040 static int
1041 acpi_cpu_usage_sysctl(SYSCTL_HANDLER_ARGS)
1042 {
1043     struct sbuf	 sb;
1044     char	 buf[128];
1045     int		 i;
1046     uintmax_t	 fract, sum, whole;
1047 
1048     sum = 0;
1049     for (i = 0; i < cpu_cx_count; i++)
1050 	sum += cpu_cx_stats[i];
1051     sbuf_new(&sb, buf, sizeof(buf), SBUF_FIXEDLEN);
1052     for (i = 0; i < cpu_cx_count; i++) {
1053 	if (sum > 0) {
1054 	    whole = (uintmax_t)cpu_cx_stats[i] * 100;
1055 	    fract = (whole % sum) * 100;
1056 	    sbuf_printf(&sb, "%u.%02u%% ", (u_int)(whole / sum),
1057 		(u_int)(fract / sum));
1058 	} else
1059 	    sbuf_printf(&sb, "0%% ");
1060     }
1061     sbuf_trim(&sb);
1062     sbuf_finish(&sb);
1063     sysctl_handle_string(oidp, sbuf_data(&sb), sbuf_len(&sb), req);
1064     sbuf_delete(&sb);
1065 
1066     return (0);
1067 }
1068 
1069 static int
1070 acpi_cpu_cx_lowest_sysctl(SYSCTL_HANDLER_ARGS)
1071 {
1072     struct	 acpi_cpu_softc *sc;
1073     char	 state[8];
1074     int		 val, error, i;
1075 
1076     sc = device_get_softc(cpu_devices[0]);
1077     snprintf(state, sizeof(state), "C%d", cpu_cx_lowest + 1);
1078     error = sysctl_handle_string(oidp, state, sizeof(state), req);
1079     if (error != 0 || req->newptr == NULL)
1080 	return (error);
1081     if (strlen(state) < 2 || toupper(state[0]) != 'C')
1082 	return (EINVAL);
1083     val = (int) strtol(state + 1, NULL, 10) - 1;
1084     if (val < 0 || val > cpu_cx_count - 1)
1085 	return (EINVAL);
1086 
1087     ACPI_SERIAL_BEGIN(cpu);
1088     cpu_cx_lowest = val;
1089 
1090     /* If not disabling, cache the new lowest non-C3 state. */
1091     cpu_non_c3 = 0;
1092     for (i = cpu_cx_lowest; i >= 0; i--) {
1093 	if (sc->cpu_cx_states[i].type < ACPI_STATE_C3) {
1094 	    cpu_non_c3 = i;
1095 	    break;
1096 	}
1097     }
1098 
1099     /* Reset the statistics counters. */
1100     bzero(cpu_cx_stats, sizeof(cpu_cx_stats));
1101     ACPI_SERIAL_END(cpu);
1102 
1103     return (0);
1104 }
1105