2 * Copyright (c) 2011 NetApp, Inc.
5 * Redistribution and use in source and binary forms, with or without
6 * modification, are permitted provided that the following conditions
8 * 1. Redistributions of source code must retain the above copyright
9 * notice, this list of conditions and the following disclaimer.
10 * 2. Redistributions in binary form must reproduce the above copyright
11 * notice, this list of conditions and the following disclaimer in the
12 * documentation and/or other materials provided with the distribution.
14 * THIS SOFTWARE IS PROVIDED BY NETAPP, INC ``AS IS'' AND
15 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
16 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
17 * ARE DISCLAIMED. IN NO EVENT SHALL NETAPP, INC OR CONTRIBUTORS BE LIABLE
18 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
19 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
20 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
21 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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23 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
29 #include <sys/cdefs.h>
30 __FBSDID("$FreeBSD$");
34 #include <machine/clock.h>
43 #define TIMER_SEL_MASK 0xc0
44 #define TIMER_RW_MASK 0x30
45 #define TIMER_MODE_MASK 0x0f
46 #define TIMER_SEL_READBACK 0xc0
48 #define TIMER_DIV(freq, hz) (((freq) + (hz) / 2) / (hz))
50 #define PIT_8254_FREQ 1193182
51 static const int nsecs_per_tick = 1000000000 / PIT_8254_FREQ;
54 struct timeval tv; /* uptime when counter was loaded */
55 uint16_t initial; /* initial counter value */
63 timevalfix(struct timeval *t1)
66 if (t1->tv_usec < 0) {
68 t1->tv_usec += 1000000;
70 if (t1->tv_usec >= 1000000) {
72 t1->tv_usec -= 1000000;
77 timevalsub(struct timeval *t1, const struct timeval *t2)
80 t1->tv_sec -= t2->tv_sec;
81 t1->tv_usec -= t2->tv_usec;
86 latch(struct counter *c)
90 uint64_t delta_nsecs, delta_ticks;
92 /* cannot latch a new value until the old one has been consumed */
96 if (c->initial == 0 || c->initial == 1) {
98 * XXX the program that runs the VM can be stopped and
99 * restarted at any time. This means that state that was
100 * created by the guest is destroyed between invocations
103 * If the counter's initial value is not programmed we
104 * assume a value that would be set to generate 'guest_hz'
105 * interrupts per second.
107 c->initial = TIMER_DIV(PIT_8254_FREQ, guest_hz);
108 gettimeofday(&c->tv, NULL);
111 (void)gettimeofday(&tv2, NULL);
112 timevalsub(&tv2, &c->tv);
113 delta_nsecs = tv2.tv_sec * 1000000000 + tv2.tv_usec * 1000;
114 delta_ticks = delta_nsecs / nsecs_per_tick;
116 lval = c->initial - delta_ticks % c->initial;
118 c->ol[1] = lval; /* LSB */
119 c->ol[0] = lval >> 8; /* MSB */
123 pit_8254_handler(struct vmctx *ctx, int vcpu, int in, int port, int bytes,
124 uint32_t *eax, void *arg)
130 static struct counter counter[3];
137 if (port == TIMER_MODE) {
139 sel = val & TIMER_SEL_MASK;
140 rw = val & TIMER_RW_MASK;
141 mode = val & TIMER_MODE_MASK;
143 if (sel == TIMER_SEL_READBACK)
145 if (rw != TIMER_LATCH && rw != TIMER_16BIT)
148 if (rw != TIMER_LATCH) {
150 * Counter mode is not affected when issuing a
153 if (mode != TIMER_RATEGEN && mode != TIMER_SQWAVE)
157 c = &counter[sel >> 6];
158 if (rw == TIMER_LATCH)
161 c->olbyte = 0; /* reset latch after reprogramming */
167 assert(port >= TIMER_CNTR0 && port <= TIMER_CNTR2);
168 c = &counter[port - TIMER_CNTR0];
173 * The spec says that once the output latch is completely
174 * read it should revert to "following" the counter. We don't
175 * do this because it is hard and any reasonable OS should
176 * always latch the counter before trying to read it.
180 *eax = c->ol[--c->olbyte];
182 c->cr[c->crbyte++] = *eax;
183 if (c->crbyte == 2) {
185 c->initial = c->cr[0] | (uint16_t)c->cr[1] << 8;
188 gettimeofday(&c->tv, NULL);
195 INOUT_PORT(8254, TIMER_MODE, IOPORT_F_OUT, pit_8254_handler);
196 INOUT_PORT(8254, TIMER_CNTR0, IOPORT_F_INOUT, pit_8254_handler);
197 INOUT_PORT(8254, TIMER_CNTR1, IOPORT_F_INOUT, pit_8254_handler);
198 INOUT_PORT(8254, TIMER_CNTR2, IOPORT_F_INOUT, pit_8254_handler);