xref: /freebsd/sys/amd64/vmm/io/vatpit.c (revision 0957b409) 
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/kernel.h>
35 #include <sys/lock.h>
36 #include <sys/malloc.h>
37 #include <sys/mutex.h>
38 #include <sys/systm.h>
39 
40 #include <machine/vmm.h>
41 
42 #include "vmm_ktr.h"
43 #include "vatpic.h"
44 #include "vioapic.h"
45 #include "vatpit.h"
46 
47 static MALLOC_DEFINE(M_VATPIT, "atpit", "bhyve virtual atpit (8254)");
48 
49 #define	VATPIT_LOCK(vatpit)		mtx_lock_spin(&((vatpit)->mtx))
50 #define	VATPIT_UNLOCK(vatpit)		mtx_unlock_spin(&((vatpit)->mtx))
51 #define	VATPIT_LOCKED(vatpit)		mtx_owned(&((vatpit)->mtx))
52 
53 #define	TIMER_SEL_MASK		0xc0
54 #define	TIMER_RW_MASK		0x30
55 #define	TIMER_MODE_MASK		0x0f
56 #define	TIMER_SEL_READBACK	0xc0
57 
58 #define	TIMER_STS_OUT		0x80
59 #define	TIMER_STS_NULLCNT	0x40
60 
61 #define	TIMER_RB_LCTR		0x20
62 #define	TIMER_RB_LSTATUS	0x10
63 #define	TIMER_RB_CTR_2		0x08
64 #define	TIMER_RB_CTR_1		0x04
65 #define	TIMER_RB_CTR_0		0x02
66 
67 #define	TMR2_OUT_STS		0x20
68 
69 #define	PIT_8254_FREQ		1193182
70 #define	TIMER_DIV(freq, hz)	(((freq) + (hz) / 2) / (hz))
71 
72 struct vatpit_callout_arg {
73 	struct vatpit	*vatpit;
74 	int		channel_num;
75 };
76 
77 
78 struct channel {
79 	int		mode;
80 	uint16_t	initial;	/* initial counter value */
81 	sbintime_t	now_sbt;	/* uptime when counter was loaded */
82 	uint8_t		cr[2];
83 	uint8_t		ol[2];
84 	bool		slatched;	/* status latched */
85 	uint8_t		status;
86 	int		crbyte;
87 	int		olbyte;
88 	int		frbyte;
89 	struct callout	callout;
90 	sbintime_t	callout_sbt;	/* target time */
91 	struct vatpit_callout_arg callout_arg;
92 };
93 
94 struct vatpit {
95 	struct vm	*vm;
96 	struct mtx	mtx;
97 
98 	sbintime_t	freq_sbt;
99 
100 	struct channel	channel[3];
101 };
102 
103 static void pit_timer_start_cntr0(struct vatpit *vatpit);
104 
105 static int
106 vatpit_get_out(struct vatpit *vatpit, int channel)
107 {
108 	struct channel *c;
109 	sbintime_t delta_ticks;
110 	int out;
111 
112 	c = &vatpit->channel[channel];
113 
114 	switch (c->mode) {
115 	case TIMER_INTTC:
116 		delta_ticks = (sbinuptime() - c->now_sbt) / vatpit->freq_sbt;
117 		out = ((c->initial - delta_ticks) <= 0);
118 		break;
119 	default:
120 		out = 0;
121 		break;
122 	}
123 
124 	return (out);
125 }
126 
127 static void
128 vatpit_callout_handler(void *a)
129 {
130 	struct vatpit_callout_arg *arg = a;
131 	struct vatpit *vatpit;
132 	struct callout *callout;
133 	struct channel *c;
134 
135 	vatpit = arg->vatpit;
136 	c = &vatpit->channel[arg->channel_num];
137 	callout = &c->callout;
138 
139 	VM_CTR1(vatpit->vm, "atpit t%d fired", arg->channel_num);
140 
141 	VATPIT_LOCK(vatpit);
142 
143 	if (callout_pending(callout))		/* callout was reset */
144 		goto done;
145 
146 	if (!callout_active(callout))		/* callout was stopped */
147 		goto done;
148 
149 	callout_deactivate(callout);
150 
151 	if (c->mode == TIMER_RATEGEN) {
152 		pit_timer_start_cntr0(vatpit);
153 	}
154 
155 	vatpic_pulse_irq(vatpit->vm, 0);
156 	vioapic_pulse_irq(vatpit->vm, 2);
157 
158 done:
159 	VATPIT_UNLOCK(vatpit);
160 	return;
161 }
162 
163 static void
164 pit_timer_start_cntr0(struct vatpit *vatpit)
165 {
166 	struct channel *c;
167 	sbintime_t now, delta, precision;
168 
169 	c = &vatpit->channel[0];
170 	if (c->initial != 0) {
171 		delta = c->initial * vatpit->freq_sbt;
172 		precision = delta >> tc_precexp;
173 		c->callout_sbt = c->callout_sbt + delta;
174 
175 		/*
176 		 * Reset 'callout_sbt' if the time that the callout
177 		 * was supposed to fire is more than 'c->initial'
178 		 * ticks in the past.
179 		 */
180 		now = sbinuptime();
181 		if (c->callout_sbt < now)
182 			c->callout_sbt = now + delta;
183 
184 		callout_reset_sbt(&c->callout, c->callout_sbt,
185 		    precision, vatpit_callout_handler, &c->callout_arg,
186 		    C_ABSOLUTE);
187 	}
188 }
189 
190 static uint16_t
191 pit_update_counter(struct vatpit *vatpit, struct channel *c, bool latch)
192 {
193 	uint16_t lval;
194 	sbintime_t delta_ticks;
195 
196 	/* cannot latch a new value until the old one has been consumed */
197 	if (latch && c->olbyte != 0)
198 		return (0);
199 
200 	if (c->initial == 0) {
201 		/*
202 		 * This is possibly an o/s bug - reading the value of
203 		 * the timer without having set up the initial value.
204 		 *
205 		 * The original user-space version of this code set
206 		 * the timer to 100hz in this condition; do the same
207 		 * here.
208 		 */
209 		c->initial = TIMER_DIV(PIT_8254_FREQ, 100);
210 		c->now_sbt = sbinuptime();
211 		c->status &= ~TIMER_STS_NULLCNT;
212 	}
213 
214 	delta_ticks = (sbinuptime() - c->now_sbt) / vatpit->freq_sbt;
215 
216 	lval = c->initial - delta_ticks % c->initial;
217 
218 	if (latch) {
219 		c->olbyte = 2;
220 		c->ol[1] = lval;		/* LSB */
221 		c->ol[0] = lval >> 8;		/* MSB */
222 	}
223 
224 	return (lval);
225 }
226 
227 static int
228 pit_readback1(struct vatpit *vatpit, int channel, uint8_t cmd)
229 {
230 	struct channel *c;
231 
232 	c = &vatpit->channel[channel];
233 
234 	/*
235 	 * Latch the count/status of the timer if not already latched.
236 	 * N.B. that the count/status latch-select bits are active-low.
237 	 */
238 	if (!(cmd & TIMER_RB_LCTR) && !c->olbyte) {
239 		(void) pit_update_counter(vatpit, c, true);
240 	}
241 
242 	if (!(cmd & TIMER_RB_LSTATUS) && !c->slatched) {
243 		c->slatched = true;
244 		/*
245 		 * For mode 0, see if the elapsed time is greater
246 		 * than the initial value - this results in the
247 		 * output pin being set to 1 in the status byte.
248 		 */
249 		if (c->mode == TIMER_INTTC && vatpit_get_out(vatpit, channel))
250 			c->status |= TIMER_STS_OUT;
251 		else
252 			c->status &= ~TIMER_STS_OUT;
253 	}
254 
255 	return (0);
256 }
257 
258 static int
259 pit_readback(struct vatpit *vatpit, uint8_t cmd)
260 {
261 	int error;
262 
263 	/*
264 	 * The readback command can apply to all timers.
265 	 */
266 	error = 0;
267 	if (cmd & TIMER_RB_CTR_0)
268 		error = pit_readback1(vatpit, 0, cmd);
269 	if (!error && cmd & TIMER_RB_CTR_1)
270 		error = pit_readback1(vatpit, 1, cmd);
271 	if (!error && cmd & TIMER_RB_CTR_2)
272 		error = pit_readback1(vatpit, 2, cmd);
273 
274 	return (error);
275 }
276 
277 
278 static int
279 vatpit_update_mode(struct vatpit *vatpit, uint8_t val)
280 {
281 	struct channel *c;
282 	int sel, rw, mode;
283 
284 	sel = val & TIMER_SEL_MASK;
285 	rw = val & TIMER_RW_MASK;
286 	mode = val & TIMER_MODE_MASK;
287 
288 	if (sel == TIMER_SEL_READBACK)
289 		return (pit_readback(vatpit, val));
290 
291 	if (rw != TIMER_LATCH && rw != TIMER_16BIT)
292 		return (-1);
293 
294 	if (rw != TIMER_LATCH) {
295 		/*
296 		 * Counter mode is not affected when issuing a
297 		 * latch command.
298 		 */
299 		if (mode != TIMER_INTTC &&
300 		    mode != TIMER_RATEGEN &&
301 		    mode != TIMER_SQWAVE &&
302 		    mode != TIMER_SWSTROBE)
303 			return (-1);
304 	}
305 
306 	c = &vatpit->channel[sel >> 6];
307 	if (rw == TIMER_LATCH)
308 		pit_update_counter(vatpit, c, true);
309 	else {
310 		c->mode = mode;
311 		c->olbyte = 0;	/* reset latch after reprogramming */
312 		c->status |= TIMER_STS_NULLCNT;
313 	}
314 
315 	return (0);
316 }
317 
318 int
319 vatpit_handler(struct vm *vm, int vcpuid, bool in, int port, int bytes,
320     uint32_t *eax)
321 {
322 	struct vatpit *vatpit;
323 	struct channel *c;
324 	uint8_t val;
325 	int error;
326 
327 	vatpit = vm_atpit(vm);
328 
329 	if (bytes != 1)
330 		return (-1);
331 
332 	val = *eax;
333 
334 	if (port == TIMER_MODE) {
335 		if (in) {
336 			VM_CTR0(vatpit->vm, "vatpit attempt to read mode");
337 			return (-1);
338 		}
339 
340 		VATPIT_LOCK(vatpit);
341 		error = vatpit_update_mode(vatpit, val);
342 		VATPIT_UNLOCK(vatpit);
343 
344 		return (error);
345 	}
346 
347 	/* counter ports */
348 	KASSERT(port >= TIMER_CNTR0 && port <= TIMER_CNTR2,
349 	    ("invalid port 0x%x", port));
350 	c = &vatpit->channel[port - TIMER_CNTR0];
351 
352 	VATPIT_LOCK(vatpit);
353 	if (in && c->slatched) {
354 		/*
355 		 * Return the status byte if latched
356 		 */
357 		*eax = c->status;
358 		c->slatched = false;
359 		c->status = 0;
360 	} else if (in) {
361 		/*
362 		 * The spec says that once the output latch is completely
363 		 * read it should revert to "following" the counter. Use
364 		 * the free running counter for this case (i.e. Linux
365 		 * TSC calibration). Assuming the access mode is 16-bit,
366 		 * toggle the MSB/LSB bit on each read.
367 		 */
368 		if (c->olbyte == 0) {
369 			uint16_t tmp;
370 
371 			tmp = pit_update_counter(vatpit, c, false);
372 			if (c->frbyte)
373 				tmp >>= 8;
374 			tmp &= 0xff;
375 			*eax = tmp;
376 			c->frbyte ^= 1;
377 		}  else
378 			*eax = c->ol[--c->olbyte];
379 	} else {
380 		c->cr[c->crbyte++] = *eax;
381 		if (c->crbyte == 2) {
382 			c->status &= ~TIMER_STS_NULLCNT;
383 			c->frbyte = 0;
384 			c->crbyte = 0;
385 			c->initial = c->cr[0] | (uint16_t)c->cr[1] << 8;
386 			c->now_sbt = sbinuptime();
387 			/* Start an interval timer for channel 0 */
388 			if (port == TIMER_CNTR0) {
389 				c->callout_sbt = c->now_sbt;
390 				pit_timer_start_cntr0(vatpit);
391 			}
392 			if (c->initial == 0)
393 				c->initial = 0xffff;
394 		}
395 	}
396 	VATPIT_UNLOCK(vatpit);
397 
398 	return (0);
399 }
400 
401 int
402 vatpit_nmisc_handler(struct vm *vm, int vcpuid, bool in, int port, int bytes,
403     uint32_t *eax)
404 {
405 	struct vatpit *vatpit;
406 
407 	vatpit = vm_atpit(vm);
408 
409 	if (in) {
410 			VATPIT_LOCK(vatpit);
411 			if (vatpit_get_out(vatpit, 2))
412 				*eax = TMR2_OUT_STS;
413 			else
414 				*eax = 0;
415 
416 			VATPIT_UNLOCK(vatpit);
417 	}
418 
419 	return (0);
420 }
421 
422 struct vatpit *
423 vatpit_init(struct vm *vm)
424 {
425 	struct vatpit *vatpit;
426 	struct bintime bt;
427 	struct vatpit_callout_arg *arg;
428 	int i;
429 
430 	vatpit = malloc(sizeof(struct vatpit), M_VATPIT, M_WAITOK | M_ZERO);
431 	vatpit->vm = vm;
432 
433 	mtx_init(&vatpit->mtx, "vatpit lock", NULL, MTX_SPIN);
434 
435 	FREQ2BT(PIT_8254_FREQ, &bt);
436 	vatpit->freq_sbt = bttosbt(bt);
437 
438 	for (i = 0; i < 3; i++) {
439 		callout_init(&vatpit->channel[i].callout, 1);
440 		arg = &vatpit->channel[i].callout_arg;
441 		arg->vatpit = vatpit;
442 		arg->channel_num = i;
443 	}
444 
445 	return (vatpit);
446 }
447 
448 void
449 vatpit_cleanup(struct vatpit *vatpit)
450 {
451 	int i;
452 
453 	for (i = 0; i < 3; i++)
454 		callout_drain(&vatpit->channel[i].callout);
455 
456 	free(vatpit, M_VATPIT);
457 }
458