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 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 int acpi_timer_test(void);
90 static device_method_t acpi_timer_methods[] = {
91 DEVMETHOD(device_identify, acpi_timer_identify),
92 DEVMETHOD(device_probe, acpi_timer_probe),
93 DEVMETHOD(device_attach, acpi_timer_attach),
98 static driver_t acpi_timer_driver = {
104 static devclass_t acpi_timer_devclass;
105 DRIVER_MODULE(acpi_timer, acpi, acpi_timer_driver, acpi_timer_devclass, NULL, NULL);
106 MODULE_DEPEND(acpi_timer, acpi, 1, 1, 1);
109 acpi_timer_read(void)
111 return (bus_space_read_4(acpi_timer_bst, acpi_timer_bsh, 0));
115 * Locate the ACPI timer using the FADT, set up and allocate the I/O resources
119 acpi_timer_identify(driver_t *driver, device_t parent)
126 * Just try once, do nothing if the 'acpi' bus is rescanned.
128 if (device_get_state(parent) == DS_ATTACHED)
131 ACPI_FUNCTION_TRACE((char *)(uintptr_t)__func__);
133 if (acpi_disabled("timer") || acpi_timer_dev)
136 if ((dev = BUS_ADD_CHILD(parent, parent, 0, "acpi_timer", 0)) == NULL) {
137 device_printf(parent, "could not add acpi_timer0\n");
140 acpi_timer_dev = dev;
142 switch (AcpiGbl_FADT.XPmTimerBlock.SpaceId) {
143 case ACPI_ADR_SPACE_SYSTEM_MEMORY:
144 rtype = SYS_RES_MEMORY;
146 case ACPI_ADR_SPACE_SYSTEM_IO:
147 rtype = SYS_RES_IOPORT;
153 rlen = AcpiGbl_FADT.PmTimerLength;
154 rstart = AcpiGbl_FADT.XPmTimerBlock.Address;
155 if (bus_set_resource(dev, rtype, rid, rstart, rlen, -1)) {
156 device_printf(dev, "couldn't set resource (%s 0x%lx+0x%lx)\n",
157 (rtype == SYS_RES_IOPORT) ? "port" : "mem", rstart, rlen);
164 acpi_timer_probe(device_t dev)
167 int i, j, rid, rtype;
169 ACPI_FUNCTION_TRACE((char *)(uintptr_t)__func__);
171 if (dev != acpi_timer_dev)
174 switch (AcpiGbl_FADT.XPmTimerBlock.SpaceId) {
175 case ACPI_ADR_SPACE_SYSTEM_MEMORY:
176 rtype = SYS_RES_MEMORY;
178 case ACPI_ADR_SPACE_SYSTEM_IO:
179 rtype = SYS_RES_IOPORT;
185 acpi_timer_reg = bus_alloc_resource_any(dev, rtype, &rid, RF_ACTIVE);
186 if (acpi_timer_reg == NULL) {
187 device_printf(dev, "couldn't allocate resource (%s 0x%lx)\n",
188 (rtype == SYS_RES_IOPORT) ? "port" : "mem",
189 (u_long)AcpiGbl_FADT.XPmTimerBlock.Address);
192 acpi_timer_bsh = rman_get_bushandle(acpi_timer_reg);
193 acpi_timer_bst = rman_get_bustag(acpi_timer_reg);
194 if ((AcpiGbl_FADT.Flags & ACPI_FADT_32BIT_TIMER) != 0)
195 acpi_counter_mask = 0xffffffff;
197 acpi_counter_mask = 0x00ffffff;
200 * If all tests of the counter succeed, use the ACPI-fast method. If
201 * at least one failed, default to using the safe routine, which reads
202 * the timer multiple times to get a consistent value before returning.
205 for (i = 0; i < 10; i++)
206 j += acpi_timer_test();
208 if (acpi_counter_mask == 0xffffffff) {
209 acpi_cputimer.name = "ACPI-fast";
210 acpi_cputimer.count = acpi_timer_get_timecount;
212 acpi_cputimer.name = "ACPI-fast24";
213 acpi_cputimer.count = acpi_timer_get_timecount24;
216 if (acpi_counter_mask == 0xffffffff)
217 acpi_cputimer.name = "ACPI-safe";
219 acpi_cputimer.name = "ACPI-safe24";
220 acpi_cputimer.count = acpi_timer_get_timecount_safe;
223 ksprintf(desc, "%d-bit timer at 3.579545MHz",
224 (AcpiGbl_FADT.Flags & ACPI_FADT_32BIT_TIMER) ? 32 : 24);
225 device_set_desc_copy(dev, desc);
227 cputimer_register(&acpi_cputimer);
228 cputimer_select(&acpi_cputimer, 0);
229 /* Release the resource, we'll allocate it again during attach. */
230 bus_release_resource(dev, rtype, rid, acpi_timer_reg);
235 acpi_timer_attach(device_t dev)
239 ACPI_FUNCTION_TRACE((char *)(uintptr_t)__func__);
241 switch (AcpiGbl_FADT.XPmTimerBlock.SpaceId) {
242 case ACPI_ADR_SPACE_SYSTEM_MEMORY:
243 rtype = SYS_RES_MEMORY;
245 case ACPI_ADR_SPACE_SYSTEM_IO:
246 rtype = SYS_RES_IOPORT;
252 acpi_timer_reg = bus_alloc_resource_any(dev, rtype, &rid, RF_ACTIVE);
253 if (acpi_timer_reg == NULL)
255 acpi_timer_bsh = rman_get_bushandle(acpi_timer_reg);
256 acpi_timer_bst = rman_get_bustag(acpi_timer_reg);
261 * Construct the timer. Adjust the base so the system clock does not
265 acpi_timer_construct(struct cputimer *timer, sysclock_t oldclock)
268 timer->base = oldclock - acpi_timer_get_timecount_safe();
272 * Fetch current time value from reliable hardware.
274 * The cputimer interface requires a 32 bit return value. If the ACPI timer
275 * is only 24 bits then we have to keep track of the upper 8 bits on our
278 * XXX we could probably get away with using a per-cpu field for this and
279 * just use interrupt disablement instead of clock_lock.
282 acpi_timer_get_timecount24(void)
287 counter = acpi_timer_read();
288 if (counter < acpi_last_counter)
289 acpi_cputimer.base += 0x01000000;
290 acpi_last_counter = counter;
291 counter += acpi_cputimer.base;
297 acpi_timer_get_timecount(void)
299 return (acpi_timer_read() + acpi_cputimer.base);
303 * Fetch current time value from hardware that may not correctly
304 * latch the counter. We need to read until we have three monotonic
305 * samples and then use the middle one, otherwise we are not protected
306 * against the fact that the bits can be wrong in two directions. If
307 * we only cared about monosity, two reads would be enough.
310 acpi_timer_get_timecount_safe(void)
314 if (acpi_counter_mask != 0xffffffff)
317 u2 = acpi_timer_read();
318 u3 = acpi_timer_read();
322 u3 = acpi_timer_read();
323 } while (u1 > u2 || u2 > u3);
325 if (acpi_counter_mask != 0xffffffff) {
326 if (u2 < acpi_last_counter)
327 acpi_cputimer.base += 0x01000000;
328 acpi_last_counter = u2;
331 return (u2 + acpi_cputimer.base);
335 * Timecounter freqency adjustment interface.
338 acpi_timer_sysctl_freq(SYSCTL_HANDLER_ARGS)
343 if (acpi_cputimer.freq == 0)
345 freq = acpi_cputimer.freq;
346 error = sysctl_handle_int(oidp, &freq, sizeof(freq), req);
347 if (error == 0 && req->newptr != NULL)
348 cputimer_set_frequency(&acpi_cputimer, freq);
353 SYSCTL_PROC(_machdep, OID_AUTO, acpi_timer_freq, CTLTYPE_INT | CTLFLAG_RW,
354 0, sizeof(u_int), acpi_timer_sysctl_freq, "I", "ACPI timer frequency");
357 * Some ACPI timers are known or believed to suffer from implementation
358 * problems which can lead to erroneous values being read. This function
359 * tests for consistent results from the timer and returns 1 if it believes
360 * the timer is consistent, otherwise it returns 0.
362 * It appears the cause is that the counter is not latched to the PCI bus
365 * ] 20. ACPI Timer Errata
367 * ] Problem: The power management timer may return improper result when
368 * ] read. Although the timer value settles properly after incrementing,
369 * ] while incrementing there is a 3nS window every 69.8nS where the
370 * ] timer value is indeterminate (a 4.2% chance that the data will be
371 * ] incorrect when read). As a result, the ACPI free running count up
372 * ] timer specification is violated due to erroneous reads. Implication:
373 * ] System hangs due to the "inaccuracy" of the timer when used by
374 * ] software for time critical events and delays.
376 * ] Workaround: Read the register twice and compare.
377 * ] Status: This will not be fixed in the PIIX4 or PIIX4E, it is fixed
382 acpi_timer_test(void)
385 int min, max, n, delta;
391 /* Test the timer with interrupts disabled to get accurate results. */
392 #if defined(__i386__)
394 #elif defined(__x86_64__)
397 #error "no read_eflags"
400 last = acpi_timer_read();
401 for (n = 0; n < 2000; n++) {
402 this = acpi_timer_read();
403 delta = acpi_TimerDelta(this, last);
406 else if (delta < min)
410 #if defined(__i386__)
412 #elif defined(__x86_64__)
415 #error "no read_eflags"
420 else if (min < 0 || max == 0)
425 kprintf("ACPI timer looks %s min = %d, max = %d, width = %d\n",
427 min, max, max - min);