xref: /freebsd/sys/x86/isa/atrtc.c (revision f0cfa1b168014f56c02b83e5f28412cc5f78d117)
1 /*-
2  * SPDX-License-Identifier: BSD-2-Clause-FreeBSD
3  *
4  * Copyright (c) 2008 Poul-Henning Kamp
5  * Copyright (c) 2010 Alexander Motin <mav@FreeBSD.org>
6  * All rights reserved.
7  *
8  * Redistribution and use in source and binary forms, with or without
9  * modification, are permitted provided that the following conditions
10  * are met:
11  * 1. Redistributions of source code must retain the above copyright
12  *    notice, this list of conditions and the following disclaimer.
13  * 2. Redistributions in binary form must reproduce the above copyright
14  *    notice, this list of conditions and the following disclaimer in the
15  *    documentation and/or other materials provided with the distribution.
16  *
17  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
18  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
19  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
20  * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
21  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
22  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
23  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
24  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
25  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
26  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
27  * SUCH DAMAGE.
28  *
29  * $FreeBSD$
30  */
31 
32 #include <sys/cdefs.h>
33 __FBSDID("$FreeBSD$");
34 
35 #include "opt_isa.h"
36 
37 #include <sys/param.h>
38 #include <sys/systm.h>
39 #include <sys/bus.h>
40 #include <sys/clock.h>
41 #include <sys/lock.h>
42 #include <sys/mutex.h>
43 #include <sys/kdb.h>
44 #include <sys/kernel.h>
45 #include <sys/module.h>
46 #include <sys/proc.h>
47 #include <sys/rman.h>
48 #include <sys/timeet.h>
49 
50 #include <isa/rtc.h>
51 #ifdef DEV_ISA
52 #include <isa/isareg.h>
53 #include <isa/isavar.h>
54 #endif
55 #include <machine/intr_machdep.h>
56 #include "clock_if.h"
57 
58 /*
59  * clock_lock protects low-level access to individual hardware registers.
60  * atrtc_time_lock protects the entire sequence of accessing multiple registers
61  * to read or write the date and time.
62  */
63 #define	RTC_LOCK	do { if (!kdb_active) mtx_lock_spin(&clock_lock); } while (0)
64 #define	RTC_UNLOCK	do { if (!kdb_active) mtx_unlock_spin(&clock_lock); } while (0)
65 
66 struct mtx atrtc_time_lock;
67 MTX_SYSINIT(atrtc_lock_init, &atrtc_time_lock, "atrtc", MTX_DEF);
68 
69 int	atrtcclock_disable = 0;
70 
71 static	int	rtc_reg = -1;
72 static	u_char	rtc_statusa = RTCSA_DIVIDER | RTCSA_NOPROF;
73 static	u_char	rtc_statusb = RTCSB_24HR;
74 
75 /*
76  * RTC support routines
77  */
78 
79 int
80 rtcin(int reg)
81 {
82 	u_char val;
83 
84 	RTC_LOCK;
85 	if (rtc_reg != reg) {
86 		inb(0x84);
87 		outb(IO_RTC, reg);
88 		rtc_reg = reg;
89 		inb(0x84);
90 	}
91 	val = inb(IO_RTC + 1);
92 	RTC_UNLOCK;
93 	return (val);
94 }
95 
96 void
97 writertc(int reg, u_char val)
98 {
99 
100 	RTC_LOCK;
101 	if (rtc_reg != reg) {
102 		inb(0x84);
103 		outb(IO_RTC, reg);
104 		rtc_reg = reg;
105 		inb(0x84);
106 	}
107 	outb(IO_RTC + 1, val);
108 	inb(0x84);
109 	RTC_UNLOCK;
110 }
111 
112 static __inline int
113 readrtc(int port)
114 {
115 	int readval;
116 
117 	readval = rtcin(port);
118 	if (readval >= 0 && (readval & 0xf) < 0xa && (readval & 0xf0) < 0xa0)
119 		return (bcd2bin(readval));
120 	return (0);
121 }
122 
123 static void
124 atrtc_start(void)
125 {
126 
127 	writertc(RTC_STATUSA, rtc_statusa);
128 	writertc(RTC_STATUSB, RTCSB_24HR);
129 }
130 
131 static void
132 atrtc_rate(unsigned rate)
133 {
134 
135 	rtc_statusa = RTCSA_DIVIDER | rate;
136 	writertc(RTC_STATUSA, rtc_statusa);
137 }
138 
139 static void
140 atrtc_enable_intr(void)
141 {
142 
143 	rtc_statusb |= RTCSB_PINTR;
144 	writertc(RTC_STATUSB, rtc_statusb);
145 	rtcin(RTC_INTR);
146 }
147 
148 static void
149 atrtc_disable_intr(void)
150 {
151 
152 	rtc_statusb &= ~RTCSB_PINTR;
153 	writertc(RTC_STATUSB, rtc_statusb);
154 	rtcin(RTC_INTR);
155 }
156 
157 void
158 atrtc_restore(void)
159 {
160 
161 	/* Restore all of the RTC's "status" (actually, control) registers. */
162 	rtcin(RTC_STATUSA);	/* dummy to get rtc_reg set */
163 	writertc(RTC_STATUSB, RTCSB_24HR);
164 	writertc(RTC_STATUSA, rtc_statusa);
165 	writertc(RTC_STATUSB, rtc_statusb);
166 	rtcin(RTC_INTR);
167 }
168 
169 static void
170 atrtc_set(struct timespec *ts)
171 {
172 	struct clocktime ct;
173 
174 	clock_ts_to_ct(ts, &ct);
175 
176 	mtx_lock(&atrtc_time_lock);
177 
178 	/* Disable RTC updates and interrupts. */
179 	writertc(RTC_STATUSB, RTCSB_HALT | RTCSB_24HR);
180 
181 	writertc(RTC_SEC, bin2bcd(ct.sec)); 		/* Write back Seconds */
182 	writertc(RTC_MIN, bin2bcd(ct.min)); 		/* Write back Minutes */
183 	writertc(RTC_HRS, bin2bcd(ct.hour));		/* Write back Hours   */
184 
185 	writertc(RTC_WDAY, ct.dow + 1);			/* Write back Weekday */
186 	writertc(RTC_DAY, bin2bcd(ct.day));		/* Write back Day */
187 	writertc(RTC_MONTH, bin2bcd(ct.mon));           /* Write back Month   */
188 	writertc(RTC_YEAR, bin2bcd(ct.year % 100));	/* Write back Year    */
189 #ifdef USE_RTC_CENTURY
190 	writertc(RTC_CENTURY, bin2bcd(ct.year / 100));	/* ... and Century    */
191 #endif
192 
193 	/* Re-enable RTC updates and interrupts. */
194 	writertc(RTC_STATUSB, rtc_statusb);
195 	rtcin(RTC_INTR);
196 
197 	mtx_unlock(&atrtc_time_lock);
198 }
199 
200 /**********************************************************************
201  * RTC driver for subr_rtc
202  */
203 
204 struct atrtc_softc {
205 	int port_rid, intr_rid;
206 	struct resource *port_res;
207 	struct resource *intr_res;
208 	void *intr_handler;
209 	struct eventtimer et;
210 };
211 
212 static int
213 rtc_start(struct eventtimer *et, sbintime_t first, sbintime_t period)
214 {
215 
216 	atrtc_rate(max(fls(period + (period >> 1)) - 17, 1));
217 	atrtc_enable_intr();
218 	return (0);
219 }
220 
221 static int
222 rtc_stop(struct eventtimer *et)
223 {
224 
225 	atrtc_disable_intr();
226 	return (0);
227 }
228 
229 /*
230  * This routine receives statistical clock interrupts from the RTC.
231  * As explained above, these occur at 128 interrupts per second.
232  * When profiling, we receive interrupts at a rate of 1024 Hz.
233  *
234  * This does not actually add as much overhead as it sounds, because
235  * when the statistical clock is active, the hardclock driver no longer
236  * needs to keep (inaccurate) statistics on its own.  This decouples
237  * statistics gathering from scheduling interrupts.
238  *
239  * The RTC chip requires that we read status register C (RTC_INTR)
240  * to acknowledge an interrupt, before it will generate the next one.
241  * Under high interrupt load, rtcintr() can be indefinitely delayed and
242  * the clock can tick immediately after the read from RTC_INTR.  In this
243  * case, the mc146818A interrupt signal will not drop for long enough
244  * to register with the 8259 PIC.  If an interrupt is missed, the stat
245  * clock will halt, considerably degrading system performance.  This is
246  * why we use 'while' rather than a more straightforward 'if' below.
247  * Stat clock ticks can still be lost, causing minor loss of accuracy
248  * in the statistics, but the stat clock will no longer stop.
249  */
250 static int
251 rtc_intr(void *arg)
252 {
253 	struct atrtc_softc *sc = (struct atrtc_softc *)arg;
254 	int flag = 0;
255 
256 	while (rtcin(RTC_INTR) & RTCIR_PERIOD) {
257 		flag = 1;
258 		if (sc->et.et_active)
259 			sc->et.et_event_cb(&sc->et, sc->et.et_arg);
260 	}
261 	return(flag ? FILTER_HANDLED : FILTER_STRAY);
262 }
263 
264 /*
265  * Attach to the ISA PnP descriptors for the timer and realtime clock.
266  */
267 static struct isa_pnp_id atrtc_ids[] = {
268 	{ 0x000bd041 /* PNP0B00 */, "AT realtime clock" },
269 	{ 0 }
270 };
271 
272 static int
273 atrtc_probe(device_t dev)
274 {
275 	int result;
276 
277 	result = ISA_PNP_PROBE(device_get_parent(dev), dev, atrtc_ids);
278 	/* ENOENT means no PnP-ID, device is hinted. */
279 	if (result == ENOENT) {
280 		device_set_desc(dev, "AT realtime clock");
281 		return (BUS_PROBE_LOW_PRIORITY);
282 	}
283 	return (result);
284 }
285 
286 static int
287 atrtc_attach(device_t dev)
288 {
289 	struct atrtc_softc *sc;
290 	rman_res_t s;
291 	int i;
292 
293 	sc = device_get_softc(dev);
294 	sc->port_res = bus_alloc_resource(dev, SYS_RES_IOPORT, &sc->port_rid,
295 	    IO_RTC, IO_RTC + 1, 2, RF_ACTIVE);
296 	if (sc->port_res == NULL)
297 		device_printf(dev, "Warning: Couldn't map I/O.\n");
298 	atrtc_start();
299 	clock_register(dev, 1000000);
300 	bzero(&sc->et, sizeof(struct eventtimer));
301 	if (!atrtcclock_disable &&
302 	    (resource_int_value(device_get_name(dev), device_get_unit(dev),
303 	     "clock", &i) != 0 || i != 0)) {
304 		sc->intr_rid = 0;
305 		while (bus_get_resource(dev, SYS_RES_IRQ, sc->intr_rid,
306 		    &s, NULL) == 0 && s != 8)
307 			sc->intr_rid++;
308 		sc->intr_res = bus_alloc_resource(dev, SYS_RES_IRQ,
309 		    &sc->intr_rid, 8, 8, 1, RF_ACTIVE);
310 		if (sc->intr_res == NULL) {
311 			device_printf(dev, "Can't map interrupt.\n");
312 			return (0);
313 		} else if ((bus_setup_intr(dev, sc->intr_res, INTR_TYPE_CLK,
314 		    rtc_intr, NULL, sc, &sc->intr_handler))) {
315 			device_printf(dev, "Can't setup interrupt.\n");
316 			return (0);
317 		} else {
318 			/* Bind IRQ to BSP to avoid live migration. */
319 			bus_bind_intr(dev, sc->intr_res, 0);
320 		}
321 		sc->et.et_name = "RTC";
322 		sc->et.et_flags = ET_FLAGS_PERIODIC | ET_FLAGS_POW2DIV;
323 		sc->et.et_quality = 0;
324 		sc->et.et_frequency = 32768;
325 		sc->et.et_min_period = 0x00080000;
326 		sc->et.et_max_period = 0x80000000;
327 		sc->et.et_start = rtc_start;
328 		sc->et.et_stop = rtc_stop;
329 		sc->et.et_priv = dev;
330 		et_register(&sc->et);
331 	}
332 	return(0);
333 }
334 
335 static int
336 atrtc_resume(device_t dev)
337 {
338 
339 	atrtc_restore();
340 	return(0);
341 }
342 
343 static int
344 atrtc_settime(device_t dev __unused, struct timespec *ts)
345 {
346 
347 	atrtc_set(ts);
348 	return (0);
349 }
350 
351 static int
352 atrtc_gettime(device_t dev, struct timespec *ts)
353 {
354 	struct clocktime ct;
355 
356 	/* Look if we have a RTC present and the time is valid */
357 	if (!(rtcin(RTC_STATUSD) & RTCSD_PWR)) {
358 		device_printf(dev, "WARNING: Battery failure indication\n");
359 		return (EINVAL);
360 	}
361 
362 	/*
363 	 * wait for time update to complete
364 	 * If RTCSA_TUP is zero, we have at least 244us before next update.
365 	 * This is fast enough on most hardware, but a refinement would be
366 	 * to make sure that no more than 240us pass after we start reading,
367 	 * and try again if so.
368 	 */
369 	mtx_lock(&atrtc_time_lock);
370 	while (rtcin(RTC_STATUSA) & RTCSA_TUP)
371 		continue;
372 	critical_enter();
373 	ct.nsec = 0;
374 	ct.sec = readrtc(RTC_SEC);
375 	ct.min = readrtc(RTC_MIN);
376 	ct.hour = readrtc(RTC_HRS);
377 	ct.day = readrtc(RTC_DAY);
378 	ct.dow = readrtc(RTC_WDAY) - 1;
379 	ct.mon = readrtc(RTC_MONTH);
380 	ct.year = readrtc(RTC_YEAR);
381 #ifdef USE_RTC_CENTURY
382 	ct.year += readrtc(RTC_CENTURY) * 100;
383 #else
384 	ct.year += (ct.year < 80 ? 2000 : 1900);
385 #endif
386 	critical_exit();
387 	mtx_unlock(&atrtc_time_lock);
388 	/* Set dow = -1 because some clocks don't set it correctly. */
389 	ct.dow = -1;
390 	return (clock_ct_to_ts(&ct, ts));
391 }
392 
393 static device_method_t atrtc_methods[] = {
394 	/* Device interface */
395 	DEVMETHOD(device_probe,		atrtc_probe),
396 	DEVMETHOD(device_attach,	atrtc_attach),
397 	DEVMETHOD(device_detach,	bus_generic_detach),
398 	DEVMETHOD(device_shutdown,	bus_generic_shutdown),
399 	DEVMETHOD(device_suspend,	bus_generic_suspend),
400 		/* XXX stop statclock? */
401 	DEVMETHOD(device_resume,	atrtc_resume),
402 
403 	/* clock interface */
404 	DEVMETHOD(clock_gettime,	atrtc_gettime),
405 	DEVMETHOD(clock_settime,	atrtc_settime),
406 
407 	{ 0, 0 }
408 };
409 
410 static driver_t atrtc_driver = {
411 	"atrtc",
412 	atrtc_methods,
413 	sizeof(struct atrtc_softc),
414 };
415 
416 static devclass_t atrtc_devclass;
417 
418 DRIVER_MODULE(atrtc, isa, atrtc_driver, atrtc_devclass, 0, 0);
419 DRIVER_MODULE(atrtc, acpi, atrtc_driver, atrtc_devclass, 0, 0);
420 
421 #include "opt_ddb.h"
422 #ifdef DDB
423 #include <ddb/ddb.h>
424 
425 DB_SHOW_COMMAND(rtc, rtc)
426 {
427 	printf("%02x/%02x/%02x %02x:%02x:%02x, A = %02x, B = %02x, C = %02x\n",
428 		rtcin(RTC_YEAR), rtcin(RTC_MONTH), rtcin(RTC_DAY),
429 		rtcin(RTC_HRS), rtcin(RTC_MIN), rtcin(RTC_SEC),
430 		rtcin(RTC_STATUSA), rtcin(RTC_STATUSB), rtcin(RTC_INTR));
431 }
432 #endif /* DDB */
433