xref: /freebsd/sys/amd64/vmm/io/vatpit.c (revision bc96366c864c07ef352edb92017357917c75b36c) 
1 /*-
2  * Copyright (c) 2014 Tycho Nightingale <tycho.nightingale@pluribusnetworks.com>
3  * Copyright (c) 2011 NetApp, Inc.
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 NETAPP, INC ``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 NETAPP, INC 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 <sys/param.h>
32 #include <sys/types.h>
33 #include <sys/queue.h>
34 #include <sys/cpuset.h>
35 #include <sys/kernel.h>
36 #include <sys/lock.h>
37 #include <sys/malloc.h>
38 #include <sys/mutex.h>
39 #include <sys/systm.h>
40 
41 #include <machine/vmm.h>
42 
43 #include "vmm_ktr.h"
44 #include "vatpic.h"
45 #include "vioapic.h"
46 #include "vatpit.h"
47 
48 static MALLOC_DEFINE(M_VATPIT, "atpit", "bhyve virtual atpit (8254)");
49 
50 #define	VATPIT_LOCK(vatpit)		mtx_lock_spin(&((vatpit)->mtx))
51 #define	VATPIT_UNLOCK(vatpit)		mtx_unlock_spin(&((vatpit)->mtx))
52 #define	VATPIT_LOCKED(vatpit)		mtx_owned(&((vatpit)->mtx))
53 
54 #define	TIMER_SEL_MASK		0xc0
55 #define	TIMER_RW_MASK		0x30
56 #define	TIMER_MODE_MASK		0x0f
57 #define	TIMER_SEL_READBACK	0xc0
58 
59 #define	TIMER_STS_OUT		0x80
60 #define	TIMER_STS_NULLCNT	0x40
61 
62 #define	TIMER_RB_LCTR		0x20
63 #define	TIMER_RB_LSTATUS	0x10
64 #define	TIMER_RB_CTR_2		0x08
65 #define	TIMER_RB_CTR_1		0x04
66 #define	TIMER_RB_CTR_0		0x02
67 
68 #define	TMR2_OUT_STS		0x20
69 
70 #define	PIT_8254_FREQ		1193182
71 #define	TIMER_DIV(freq, hz)	(((freq) + (hz) / 2) / (hz))
72 
73 struct vatpit_callout_arg {
74 	struct vatpit	*vatpit;
75 	int		channel_num;
76 };
77 
78 
79 struct channel {
80 	int		mode;
81 	uint16_t	initial;	/* initial counter value */
82 	sbintime_t	now_sbt;	/* uptime when counter was loaded */
83 	uint8_t		cr[2];
84 	uint8_t		ol[2];
85 	bool		slatched;	/* status latched */
86 	uint8_t		status;
87 	int		crbyte;
88 	int		olbyte;
89 	int		frbyte;
90 	struct callout	callout;
91 	sbintime_t	callout_sbt;	/* target time */
92 	struct vatpit_callout_arg callout_arg;
93 };
94 
95 struct vatpit {
96 	struct vm	*vm;
97 	struct mtx	mtx;
98 
99 	sbintime_t	freq_sbt;
100 
101 	struct channel	channel[3];
102 };
103 
104 static void pit_timer_start_cntr0(struct vatpit *vatpit);
105 
106 static int
107 vatpit_get_out(struct vatpit *vatpit, int channel)
108 {
109 	struct channel *c;
110 	sbintime_t delta_ticks;
111 	int out;
112 
113 	c = &vatpit->channel[channel];
114 
115 	switch (c->mode) {
116 	case TIMER_INTTC:
117 		delta_ticks = (sbinuptime() - c->now_sbt) / vatpit->freq_sbt;
118 		out = ((c->initial - delta_ticks) <= 0);
119 		break;
120 	default:
121 		out = 0;
122 		break;
123 	}
124 
125 	return (out);
126 }
127 
128 static void
129 vatpit_callout_handler(void *a)
130 {
131 	struct vatpit_callout_arg *arg = a;
132 	struct vatpit *vatpit;
133 	struct callout *callout;
134 	struct channel *c;
135 
136 	vatpit = arg->vatpit;
137 	c = &vatpit->channel[arg->channel_num];
138 	callout = &c->callout;
139 
140 	VM_CTR1(vatpit->vm, "atpit t%d fired", arg->channel_num);
141 
142 	VATPIT_LOCK(vatpit);
143 
144 	if (callout_pending(callout))		/* callout was reset */
145 		goto done;
146 
147 	if (!callout_active(callout))		/* callout was stopped */
148 		goto done;
149 
150 	callout_deactivate(callout);
151 
152 	if (c->mode == TIMER_RATEGEN) {
153 		pit_timer_start_cntr0(vatpit);
154 	}
155 
156 	vatpic_pulse_irq(vatpit->vm, 0);
157 	vioapic_pulse_irq(vatpit->vm, 2);
158 
159 done:
160 	VATPIT_UNLOCK(vatpit);
161 	return;
162 }
163 
164 static void
165 pit_timer_start_cntr0(struct vatpit *vatpit)
166 {
167 	struct channel *c;
168 	sbintime_t now, delta, precision;
169 
170 	c = &vatpit->channel[0];
171 	if (c->initial != 0) {
172 		delta = c->initial * vatpit->freq_sbt;
173 		precision = delta >> tc_precexp;
174 		c->callout_sbt = c->callout_sbt + delta;
175 
176 		/*
177 		 * Reset 'callout_sbt' if the time that the callout
178 		 * was supposed to fire is more than 'c->initial'
179 		 * ticks in the past.
180 		 */
181 		now = sbinuptime();
182 		if (c->callout_sbt < now)
183 			c->callout_sbt = now + delta;
184 
185 		callout_reset_sbt(&c->callout, c->callout_sbt,
186 		    precision, vatpit_callout_handler, &c->callout_arg,
187 		    C_ABSOLUTE);
188 	}
189 }
190 
191 static uint16_t
192 pit_update_counter(struct vatpit *vatpit, struct channel *c, bool latch)
193 {
194 	uint16_t lval;
195 	sbintime_t delta_ticks;
196 
197 	/* cannot latch a new value until the old one has been consumed */
198 	if (latch && c->olbyte != 0)
199 		return (0);
200 
201 	if (c->initial == 0) {
202 		/*
203 		 * This is possibly an o/s bug - reading the value of
204 		 * the timer without having set up the initial value.
205 		 *
206 		 * The original user-space version of this code set
207 		 * the timer to 100hz in this condition; do the same
208 		 * here.
209 		 */
210 		c->initial = TIMER_DIV(PIT_8254_FREQ, 100);
211 		c->now_sbt = sbinuptime();
212 		c->status &= ~TIMER_STS_NULLCNT;
213 	}
214 
215 	delta_ticks = (sbinuptime() - c->now_sbt) / vatpit->freq_sbt;
216 
217 	lval = c->initial - delta_ticks % c->initial;
218 
219 	if (latch) {
220 		c->olbyte = 2;
221 		c->ol[1] = lval;		/* LSB */
222 		c->ol[0] = lval >> 8;		/* MSB */
223 	}
224 
225 	return (lval);
226 }
227 
228 static int
229 pit_readback1(struct vatpit *vatpit, int channel, uint8_t cmd)
230 {
231 	struct channel *c;
232 
233 	c = &vatpit->channel[channel];
234 
235 	/*
236 	 * Latch the count/status of the timer if not already latched.
237 	 * N.B. that the count/status latch-select bits are active-low.
238 	 */
239 	if (!(cmd & TIMER_RB_LCTR) && !c->olbyte) {
240 		(void) pit_update_counter(vatpit, c, true);
241 	}
242 
243 	if (!(cmd & TIMER_RB_LSTATUS) && !c->slatched) {
244 		c->slatched = true;
245 		/*
246 		 * For mode 0, see if the elapsed time is greater
247 		 * than the initial value - this results in the
248 		 * output pin being set to 1 in the status byte.
249 		 */
250 		if (c->mode == TIMER_INTTC && vatpit_get_out(vatpit, channel))
251 			c->status |= TIMER_STS_OUT;
252 		else
253 			c->status &= ~TIMER_STS_OUT;
254 	}
255 
256 	return (0);
257 }
258 
259 static int
260 pit_readback(struct vatpit *vatpit, uint8_t cmd)
261 {
262 	int error;
263 
264 	/*
265 	 * The readback command can apply to all timers.
266 	 */
267 	error = 0;
268 	if (cmd & TIMER_RB_CTR_0)
269 		error = pit_readback1(vatpit, 0, cmd);
270 	if (!error && cmd & TIMER_RB_CTR_1)
271 		error = pit_readback1(vatpit, 1, cmd);
272 	if (!error && cmd & TIMER_RB_CTR_2)
273 		error = pit_readback1(vatpit, 2, cmd);
274 
275 	return (error);
276 }
277 
278 
279 static int
280 vatpit_update_mode(struct vatpit *vatpit, uint8_t val)
281 {
282 	struct channel *c;
283 	int sel, rw, mode;
284 
285 	sel = val & TIMER_SEL_MASK;
286 	rw = val & TIMER_RW_MASK;
287 	mode = val & TIMER_MODE_MASK;
288 
289 	if (sel == TIMER_SEL_READBACK)
290 		return (pit_readback(vatpit, val));
291 
292 	if (rw != TIMER_LATCH && rw != TIMER_16BIT)
293 		return (-1);
294 
295 	if (rw != TIMER_LATCH) {
296 		/*
297 		 * Counter mode is not affected when issuing a
298 		 * latch command.
299 		 */
300 		if (mode != TIMER_INTTC &&
301 		    mode != TIMER_RATEGEN &&
302 		    mode != TIMER_SQWAVE &&
303 		    mode != TIMER_SWSTROBE)
304 			return (-1);
305 	}
306 
307 	c = &vatpit->channel[sel >> 6];
308 	if (rw == TIMER_LATCH)
309 		pit_update_counter(vatpit, c, true);
310 	else {
311 		c->mode = mode;
312 		c->olbyte = 0;	/* reset latch after reprogramming */
313 		c->status |= TIMER_STS_NULLCNT;
314 	}
315 
316 	return (0);
317 }
318 
319 int
320 vatpit_handler(struct vm *vm, int vcpuid, bool in, int port, int bytes,
321     uint32_t *eax)
322 {
323 	struct vatpit *vatpit;
324 	struct channel *c;
325 	uint8_t val;
326 	int error;
327 
328 	vatpit = vm_atpit(vm);
329 
330 	if (bytes != 1)
331 		return (-1);
332 
333 	val = *eax;
334 
335 	if (port == TIMER_MODE) {
336 		if (in) {
337 			VM_CTR0(vatpit->vm, "vatpit attempt to read mode");
338 			return (-1);
339 		}
340 
341 		VATPIT_LOCK(vatpit);
342 		error = vatpit_update_mode(vatpit, val);
343 		VATPIT_UNLOCK(vatpit);
344 
345 		return (error);
346 	}
347 
348 	/* counter ports */
349 	KASSERT(port >= TIMER_CNTR0 && port <= TIMER_CNTR2,
350 	    ("invalid port 0x%x", port));
351 	c = &vatpit->channel[port - TIMER_CNTR0];
352 
353 	VATPIT_LOCK(vatpit);
354 	if (in && c->slatched) {
355 		/*
356 		 * Return the status byte if latched
357 		 */
358 		*eax = c->status;
359 		c->slatched = false;
360 		c->status = 0;
361 	} else if (in) {
362 		/*
363 		 * The spec says that once the output latch is completely
364 		 * read it should revert to "following" the counter. Use
365 		 * the free running counter for this case (i.e. Linux
366 		 * TSC calibration). Assuming the access mode is 16-bit,
367 		 * toggle the MSB/LSB bit on each read.
368 		 */
369 		if (c->olbyte == 0) {
370 			uint16_t tmp;
371 
372 			tmp = pit_update_counter(vatpit, c, false);
373 			if (c->frbyte)
374 				tmp >>= 8;
375 			tmp &= 0xff;
376 			*eax = tmp;
377 			c->frbyte ^= 1;
378 		}  else
379 			*eax = c->ol[--c->olbyte];
380 	} else {
381 		c->cr[c->crbyte++] = *eax;
382 		if (c->crbyte == 2) {
383 			c->status &= ~TIMER_STS_NULLCNT;
384 			c->frbyte = 0;
385 			c->crbyte = 0;
386 			c->initial = c->cr[0] | (uint16_t)c->cr[1] << 8;
387 			c->now_sbt = sbinuptime();
388 			/* Start an interval timer for channel 0 */
389 			if (port == TIMER_CNTR0) {
390 				c->callout_sbt = c->now_sbt;
391 				pit_timer_start_cntr0(vatpit);
392 			}
393 			if (c->initial == 0)
394 				c->initial = 0xffff;
395 		}
396 	}
397 	VATPIT_UNLOCK(vatpit);
398 
399 	return (0);
400 }
401 
402 int
403 vatpit_nmisc_handler(struct vm *vm, int vcpuid, bool in, int port, int bytes,
404     uint32_t *eax)
405 {
406 	struct vatpit *vatpit;
407 
408 	vatpit = vm_atpit(vm);
409 
410 	if (in) {
411 			VATPIT_LOCK(vatpit);
412 			if (vatpit_get_out(vatpit, 2))
413 				*eax = TMR2_OUT_STS;
414 			else
415 				*eax = 0;
416 
417 			VATPIT_UNLOCK(vatpit);
418 	}
419 
420 	return (0);
421 }
422 
423 struct vatpit *
424 vatpit_init(struct vm *vm)
425 {
426 	struct vatpit *vatpit;
427 	struct bintime bt;
428 	struct vatpit_callout_arg *arg;
429 	int i;
430 
431 	vatpit = malloc(sizeof(struct vatpit), M_VATPIT, M_WAITOK | M_ZERO);
432 	vatpit->vm = vm;
433 
434 	mtx_init(&vatpit->mtx, "vatpit lock", NULL, MTX_SPIN);
435 
436 	FREQ2BT(PIT_8254_FREQ, &bt);
437 	vatpit->freq_sbt = bttosbt(bt);
438 
439 	for (i = 0; i < 3; i++) {
440 		callout_init(&vatpit->channel[i].callout, true);
441 		arg = &vatpit->channel[i].callout_arg;
442 		arg->vatpit = vatpit;
443 		arg->channel_num = i;
444 	}
445 
446 	return (vatpit);
447 }
448 
449 void
450 vatpit_cleanup(struct vatpit *vatpit)
451 {
452 	int i;
453 
454 	for (i = 0; i < 3; i++)
455 		callout_drain(&vatpit->channel[i].callout);
456 
457 	free(vatpit, M_VATPIT);
458 }
459