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 $
30 #include <sys/param.h>
32 #include <sys/kernel.h>
33 #include <sys/module.h>
34 #include <sys/sysctl.h>
35 #include <sys/systimer.h>
38 #include <machine/lock.h>
39 #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 ACPICA debugging infrastructure */
52 #define _COMPONENT ACPI_TIMER
53 ACPI_MODULE_NAME("TIMER")
55 static device_t acpi_timer_dev;
56 static UINT32 acpi_timer_resolution;
57 static sysclock_t acpi_last_counter;
59 static sysclock_t acpi_timer_get_timecount(void);
60 static sysclock_t acpi_timer_get_timecount24(void);
61 static sysclock_t acpi_timer_get_timecount_safe(void);
62 static void acpi_timer_construct(struct cputimer *timer, sysclock_t oldclock);
64 static struct cputimer acpi_cputimer = {
65 SLIST_ENTRY_INITIALIZER,
69 acpi_timer_get_timecount_safe,
70 cputimer_default_fromhz,
71 cputimer_default_fromus,
73 cputimer_default_destruct,
74 ACPI_PM_TIMER_FREQUENCY,
78 static int acpi_timer_identify(driver_t *driver, device_t parent);
79 static int acpi_timer_probe(device_t dev);
80 static int acpi_timer_attach(device_t dev);
81 static int acpi_timer_sysctl_freq(SYSCTL_HANDLER_ARGS);
83 static int acpi_timer_test(void);
85 static device_method_t acpi_timer_methods[] = {
86 DEVMETHOD(device_identify, acpi_timer_identify),
87 DEVMETHOD(device_probe, acpi_timer_probe),
88 DEVMETHOD(device_attach, acpi_timer_attach),
93 static driver_t acpi_timer_driver = {
99 static devclass_t acpi_timer_devclass;
100 DRIVER_MODULE(acpi_timer, acpi, acpi_timer_driver, acpi_timer_devclass, NULL, NULL);
101 MODULE_DEPEND(acpi_timer, acpi, 1, 1, 1);
104 * Locate the ACPI timer using the FADT, set up and allocate the I/O resources
108 acpi_timer_identify(driver_t *driver, device_t parent)
113 * Just try once, do nothing if the 'acpi' bus is rescanned.
115 if (device_get_state(parent) == DS_ATTACHED)
118 ACPI_FUNCTION_TRACE((char *)(uintptr_t)__func__);
120 if (acpi_disabled("timer") || (acpi_quirks & ACPI_Q_TIMER) ||
124 if ((dev = BUS_ADD_CHILD(parent, parent, 0, "acpi_timer", 0)) == NULL) {
125 device_printf(parent, "could not add acpi_timer0\n");
128 acpi_timer_dev = dev;
134 acpi_timer_probe(device_t dev)
136 ACPI_FUNCTION_TRACE((char *)(uintptr_t)__func__);
138 if (dev != acpi_timer_dev)
141 if (ACPI_FAILURE(AcpiGetTimerResolution(&acpi_timer_resolution)))
148 acpi_timer_attach(device_t dev)
153 ACPI_FUNCTION_TRACE((char *)(uintptr_t)__func__);
156 * If all tests of the counter succeed, use the ACPI-fast method. If
157 * at least one failed, default to using the safe routine, which reads
158 * the timer multiple times to get a consistent value before returning.
161 for (i = 0; i < 10; i++)
162 j += acpi_timer_test();
164 if (acpi_timer_resolution == 32) {
165 acpi_cputimer.name = "ACPI-fast";
166 acpi_cputimer.count = acpi_timer_get_timecount;
168 acpi_cputimer.name = "ACPI-fast24";
169 acpi_cputimer.count = acpi_timer_get_timecount24;
172 if (acpi_timer_resolution == 32)
173 acpi_cputimer.name = "ACPI-safe";
175 acpi_cputimer.name = "ACPI-safe24";
176 acpi_cputimer.count = acpi_timer_get_timecount_safe;
179 ksprintf(desc, "%u-bit timer at 3.579545MHz", acpi_timer_resolution);
180 device_set_desc_copy(dev, desc);
182 cputimer_register(&acpi_cputimer);
183 cputimer_select(&acpi_cputimer, 0);
189 * Construct the timer. Adjust the base so the system clock does not
193 acpi_timer_construct(struct cputimer *timer, sysclock_t oldclock)
196 timer->base = oldclock - acpi_timer_get_timecount_safe();
200 * Fetch current time value from reliable hardware.
202 * The cputimer interface requires a 32 bit return value. If the ACPI timer
203 * is only 24 bits then we have to keep track of the upper 8 bits on our
206 * XXX we could probably get away with using a per-cpu field for this and
207 * just use interrupt disablement instead of clock_lock.
210 acpi_timer_get_timecount24(void)
215 AcpiGetTimer(&counter);
216 if (counter < acpi_last_counter)
217 acpi_cputimer.base += 0x01000000;
218 acpi_last_counter = counter;
219 counter += acpi_cputimer.base;
225 acpi_timer_get_timecount(void)
229 AcpiGetTimer(&counter);
230 return (counter + acpi_cputimer.base);
234 * Fetch current time value from hardware that may not correctly
235 * latch the counter. We need to read until we have three monotonic
236 * samples and then use the middle one, otherwise we are not protected
237 * against the fact that the bits can be wrong in two directions. If
238 * we only cared about monosity, two reads would be enough.
241 acpi_timer_get_timecount_safe(void)
245 if (acpi_timer_resolution != 32)
254 } while (u1 > u2 || u2 > u3);
256 if (acpi_timer_resolution != 32) {
257 if (u2 < acpi_last_counter)
258 acpi_cputimer.base += 0x01000000;
259 acpi_last_counter = u2;
262 return (u2 + acpi_cputimer.base);
266 * Timecounter freqency adjustment interface.
269 acpi_timer_sysctl_freq(SYSCTL_HANDLER_ARGS)
274 if (acpi_cputimer.freq == 0)
276 freq = acpi_cputimer.freq;
277 error = sysctl_handle_int(oidp, &freq, 0, req);
278 if (error == 0 && req->newptr != NULL)
279 cputimer_set_frequency(&acpi_cputimer, freq);
284 SYSCTL_PROC(_machdep, OID_AUTO, acpi_timer_freq, CTLTYPE_INT | CTLFLAG_RW,
285 0, sizeof(u_int), acpi_timer_sysctl_freq, "I", "ACPI timer frequency");
288 * Some ACPI timers are known or believed to suffer from implementation
289 * problems which can lead to erroneous values being read. This function
290 * tests for consistent results from the timer and returns 1 if it believes
291 * the timer is consistent, otherwise it returns 0.
293 * It appears the cause is that the counter is not latched to the PCI bus
296 * ] 20. ACPI Timer Errata
298 * ] Problem: The power management timer may return improper result when
299 * ] read. Although the timer value settles properly after incrementing,
300 * ] while incrementing there is a 3nS window every 69.8nS where the
301 * ] timer value is indeterminate (a 4.2% chance that the data will be
302 * ] incorrect when read). As a result, the ACPI free running count up
303 * ] timer specification is violated due to erroneous reads. Implication:
304 * ] System hangs due to the "inaccuracy" of the timer when used by
305 * ] software for time critical events and delays.
307 * ] Workaround: Read the register twice and compare.
308 * ] Status: This will not be fixed in the PIIX4 or PIIX4E, it is fixed
313 acpi_timer_test(void)
316 int min, max, max2, n, delta;
322 /* Test the timer with interrupts disabled to get accurate results. */
323 #if defined(__i386__)
325 #elif defined(__x86_64__)
328 #error "no read_eflags"
332 for (n = 0; n < 2000; n++) {
334 delta = acpi_TimerDelta(this, last);
338 } else if (delta > max2) {
345 #if defined(__i386__)
347 #elif defined(__x86_64__)
350 #error "no read_eflags"
354 if ((max - min > 8 || delta > 3) && vmm_guest == VMM_GUEST_NONE)
356 else if (min < 0 || max == 0 || max2 == 0)
361 kprintf("ACPI timer looks %s min = %d, max = %d, width = %d\n",
363 min, max, max - min);