2 * Copyright (c) 2000, 2001 Michael Smith
3 * Copyright (c) 2000 BSDi
6 * Redistribution and use in source and binary forms, with or without
7 * modification, are permitted provided that the following conditions
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.
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
27 * $FreeBSD: src/sys/dev/acpica/acpi_timer.c,v 1.35 2004/07/22 05:42:14 njl Exp $
28 * $DragonFly: src/sys/dev/acpica5/acpi_timer.c,v 1.13 2007/10/09 09:46:56 y0netan1 Exp $
31 #include <sys/param.h>
33 #include <sys/kernel.h>
34 #include <sys/module.h>
35 #include <sys/sysctl.h>
36 #include <sys/systimer.h>
39 #include <machine/lock.h>
40 #include <bus/pci/pcivar.h>
46 * A timecounter based on the free-running ACPI timer.
48 * Based on the i386-only mp_clock.c by <phk@FreeBSD.ORG>.
51 /* Hooks for the ACPI CA debugging infrastructure */
52 #define _COMPONENT ACPI_TIMER
53 ACPI_MODULE_NAME("TIMER")
55 static device_t acpi_timer_dev
;
56 static struct resource
*acpi_timer_reg
;
57 static bus_space_handle_t acpi_timer_bsh
;
58 static bus_space_tag_t acpi_timer_bst
;
59 static sysclock_t acpi_counter_mask
;
60 static sysclock_t acpi_last_counter
;
62 #define ACPI_TIMER_FREQ (14318182 / 4)
64 static sysclock_t
acpi_timer_get_timecount(void);
65 static sysclock_t
acpi_timer_get_timecount24(void);
66 static sysclock_t
acpi_timer_get_timecount_safe(void);
67 static void acpi_timer_construct(struct cputimer
*timer
, sysclock_t oldclock
);
69 static struct cputimer acpi_cputimer
= {
70 SLIST_ENTRY_INITIALIZER
,
74 acpi_timer_get_timecount_safe
,
75 cputimer_default_fromhz
,
76 cputimer_default_fromus
,
78 cputimer_default_destruct
,
83 static int acpi_timer_identify(driver_t
*driver
, device_t parent
);
84 static int acpi_timer_probe(device_t dev
);
85 static int acpi_timer_attach(device_t dev
);
86 static int acpi_timer_sysctl_freq(SYSCTL_HANDLER_ARGS
);
88 static u_int
acpi_timer_read(void);
89 static int acpi_timer_test(void);
91 static device_method_t acpi_timer_methods
[] = {
92 DEVMETHOD(device_identify
, acpi_timer_identify
),
93 DEVMETHOD(device_probe
, acpi_timer_probe
),
94 DEVMETHOD(device_attach
, acpi_timer_attach
),
99 static driver_t acpi_timer_driver
= {
105 static devclass_t acpi_timer_devclass
;
106 DRIVER_MODULE(acpi_timer
, acpi
, acpi_timer_driver
, acpi_timer_devclass
, 0, 0);
107 MODULE_DEPEND(acpi_timer
, acpi
, 1, 1, 1);
110 acpi_timer_read(void)
112 return (bus_space_read_4(acpi_timer_bst
, acpi_timer_bsh
, 0));
116 * Locate the ACPI timer using the FADT, set up and allocate the I/O resources
120 acpi_timer_identify(driver_t
*driver
, device_t parent
)
127 * Just try once, do nothing if the 'acpi' bus is rescanned.
129 if (device_get_state(parent
) == DS_ATTACHED
)
132 ACPI_FUNCTION_TRACE((char *)(uintptr_t)__func__
);
134 if (acpi_disabled("timer") || acpi_timer_dev
)
137 if ((dev
= BUS_ADD_CHILD(parent
, parent
, 0, "acpi_timer", 0)) == NULL
) {
138 device_printf(parent
, "could not add acpi_timer0\n");
141 acpi_timer_dev
= dev
;
144 rtype
= AcpiGbl_FADT
.XPmTimerBlock
.SpaceId
?
145 SYS_RES_IOPORT
: SYS_RES_MEMORY
;
146 rlen
= AcpiGbl_FADT
.PmTimerLength
;
147 rstart
= AcpiGbl_FADT
.XPmTimerBlock
.Address
;
148 if (bus_set_resource(dev
, rtype
, rid
, rstart
, rlen
)) {
149 device_printf(dev
, "couldn't set resource (%s 0x%lx+0x%lx)\n",
150 (rtype
== SYS_RES_IOPORT
) ? "port" : "mem", rstart
, rlen
);
157 acpi_timer_probe(device_t dev
)
160 int i
, j
, rid
, rtype
;
162 ACPI_FUNCTION_TRACE((char *)(uintptr_t)__func__
);
164 if (dev
!= acpi_timer_dev
)
168 rtype
= AcpiGbl_FADT
.XPmTimerBlock
.SpaceId
?
169 SYS_RES_IOPORT
: SYS_RES_MEMORY
;
170 acpi_timer_reg
= bus_alloc_resource_any(dev
, rtype
, &rid
, RF_ACTIVE
);
171 if (acpi_timer_reg
== NULL
) {
172 device_printf(dev
, "couldn't allocate resource (%s 0x%lx)\n",
173 (rtype
== SYS_RES_IOPORT
) ? "port" : "mem",
174 (u_long
)AcpiGbl_FADT
.XPmTimerBlock
.Address
);
177 acpi_timer_bsh
= rman_get_bushandle(acpi_timer_reg
);
178 acpi_timer_bst
= rman_get_bustag(acpi_timer_reg
);
179 if ((AcpiGbl_FADT
.Flags
& ACPI_FADT_32BIT_TIMER
) != 0)
180 acpi_counter_mask
= 0xffffffff;
182 acpi_counter_mask
= 0x00ffffff;
185 * If all tests of the counter succeed, use the ACPI-fast method. If
186 * at least one failed, default to using the safe routine, which reads
187 * the timer multiple times to get a consistent value before returning.
190 for (i
= 0; i
< 10; i
++)
191 j
+= acpi_timer_test();
193 if (acpi_counter_mask
== 0xffffffff) {
194 acpi_cputimer
.name
= "ACPI-fast";
195 acpi_cputimer
.count
= acpi_timer_get_timecount
;
197 acpi_cputimer
.name
= "ACPI-fast24";
198 acpi_cputimer
.count
= acpi_timer_get_timecount24
;
201 acpi_cputimer
.name
= "ACPI-safe";
202 acpi_cputimer
.count
= acpi_timer_get_timecount_safe
;
205 ksprintf(desc
, "%d-bit timer at 3.579545MHz",
206 (AcpiGbl_FADT
.Flags
& ACPI_FADT_32BIT_TIMER
) ? 32 : 24);
207 device_set_desc_copy(dev
, desc
);
209 cputimer_register(&acpi_cputimer
);
210 cputimer_select(&acpi_cputimer
, 0);
211 /* Release the resource, we'll allocate it again during attach. */
212 bus_release_resource(dev
, rtype
, rid
, acpi_timer_reg
);
217 acpi_timer_attach(device_t dev
)
221 ACPI_FUNCTION_TRACE((char *)(uintptr_t)__func__
);
224 rtype
= AcpiGbl_FADT
.XPmTimerBlock
.SpaceId
?
225 SYS_RES_IOPORT
: SYS_RES_MEMORY
;
226 acpi_timer_reg
= bus_alloc_resource_any(dev
, rtype
, &rid
, RF_ACTIVE
);
227 if (acpi_timer_reg
== NULL
)
229 acpi_timer_bsh
= rman_get_bushandle(acpi_timer_reg
);
230 acpi_timer_bst
= rman_get_bustag(acpi_timer_reg
);
235 * Construct the timer. Adjust the base so the system clock does not
239 acpi_timer_construct(struct cputimer
*timer
, sysclock_t oldclock
)
242 timer
->base
= oldclock
- acpi_timer_get_timecount_safe();
246 * Fetch current time value from reliable hardware.
248 * The cputimer interface requires a 32 bit return value. If the ACPI timer
249 * is only 24 bits then we have to keep track of the upper 8 bits on our
252 * XXX we could probably get away with using a per-cpu field for this and
253 * just use interrupt disablement instead of clock_lock.
256 acpi_timer_get_timecount24(void)
261 counter
= acpi_timer_read();
262 if (counter
< acpi_last_counter
)
263 acpi_cputimer
.base
+= 0x01000000;
264 acpi_last_counter
= counter
;
265 counter
+= acpi_cputimer
.base
;
271 acpi_timer_get_timecount(void)
273 return (acpi_timer_read() + acpi_cputimer
.base
);
277 * Fetch current time value from hardware that may not correctly
278 * latch the counter. We need to read until we have three monotonic
279 * samples and then use the middle one, otherwise we are not protected
280 * against the fact that the bits can be wrong in two directions. If
281 * we only cared about monosity, two reads would be enough.
284 acpi_timer_get_timecount_safe(void)
288 if (acpi_counter_mask
!= 0xffffffff)
291 u2
= acpi_timer_read();
292 u3
= acpi_timer_read();
296 u3
= acpi_timer_read();
297 } while (u1
> u2
|| u2
> u3
);
299 if (acpi_counter_mask
!= 0xffffffff) {
300 if (u2
< acpi_last_counter
)
301 acpi_cputimer
.base
+= 0x01000000;
302 acpi_last_counter
= u2
;
305 return (u2
+ acpi_cputimer
.base
);
309 * Timecounter freqency adjustment interface.
312 acpi_timer_sysctl_freq(SYSCTL_HANDLER_ARGS
)
317 if (acpi_cputimer
.freq
== 0)
319 freq
= acpi_cputimer
.freq
;
320 error
= sysctl_handle_int(oidp
, &freq
, sizeof(freq
), req
);
321 if (error
== 0 && req
->newptr
!= NULL
)
322 cputimer_set_frequency(&acpi_cputimer
, freq
);
327 SYSCTL_PROC(_machdep
, OID_AUTO
, acpi_timer_freq
, CTLTYPE_INT
| CTLFLAG_RW
,
328 0, sizeof(u_int
), acpi_timer_sysctl_freq
, "I", "");
331 * Some ACPI timers are known or believed to suffer from implementation
332 * problems which can lead to erroneous values being read. This function
333 * tests for consistent results from the timer and returns 1 if it believes
334 * the timer is consistent, otherwise it returns 0.
336 * It appears the cause is that the counter is not latched to the PCI bus
339 * ] 20. ACPI Timer Errata
341 * ] Problem: The power management timer may return improper result when
342 * ] read. Although the timer value settles properly after incrementing,
343 * ] while incrementing there is a 3nS window every 69.8nS where the
344 * ] timer value is indeterminate (a 4.2% chance that the data will be
345 * ] incorrect when read). As a result, the ACPI free running count up
346 * ] timer specification is violated due to erroneous reads. Implication:
347 * ] System hangs due to the "inaccuracy" of the timer when used by
348 * ] software for time critical events and delays.
350 * ] Workaround: Read the register twice and compare.
351 * ] Status: This will not be fixed in the PIIX4 or PIIX4E, it is fixed
356 acpi_timer_test(void)
359 int min
, max
, n
, delta
;
365 /* Test the timer with interrupts disabled to get accurate results. */
368 last
= acpi_timer_read();
369 for (n
= 0; n
< 2000; n
++) {
370 this = acpi_timer_read();
371 delta
= acpi_TimerDelta(this, last
);
374 else if (delta
< min
)
382 else if (min
< 0 || max
== 0)
387 kprintf("ACPI timer looks %s min = %d, max = %d, width = %d\n",
389 min
, max
, max
- min
);