diff options
Diffstat (limited to 'usr.sbin/bhyve/pit_8254.c')
| -rw-r--r-- | usr.sbin/bhyve/pit_8254.c | 198 |
1 files changed, 198 insertions, 0 deletions
diff --git a/usr.sbin/bhyve/pit_8254.c b/usr.sbin/bhyve/pit_8254.c new file mode 100644 index 0000000..c96596a --- /dev/null +++ b/usr.sbin/bhyve/pit_8254.c @@ -0,0 +1,198 @@ +/*- + * Copyright (c) 2011 NetApp, Inc. + * All rights reserved. + * + * Redistribution and use in source and binary forms, with or without + * modification, are permitted provided that the following conditions + * are met: + * 1. Redistributions of source code must retain the above copyright + * notice, this list of conditions and the following disclaimer. + * 2. Redistributions in binary form must reproduce the above copyright + * notice, this list of conditions and the following disclaimer in the + * documentation and/or other materials provided with the distribution. + * + * THIS SOFTWARE IS PROVIDED BY NETAPP, INC ``AS IS'' AND + * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE + * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE + * ARE DISCLAIMED. IN NO EVENT SHALL NETAPP, INC OR CONTRIBUTORS BE LIABLE + * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL + * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS + * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) + * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT + * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY + * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF + * SUCH DAMAGE. + * + * $FreeBSD$ + */ + +#include <sys/cdefs.h> +__FBSDID("$FreeBSD$"); + +#include <sys/time.h> + +#include <machine/clock.h> + +#include <stdio.h> +#include <assert.h> + +#include "bhyverun.h" +#include "inout.h" +#include "pit_8254.h" + +#define TIMER_SEL_MASK 0xc0 +#define TIMER_RW_MASK 0x30 +#define TIMER_MODE_MASK 0x0f +#define TIMER_SEL_READBACK 0xc0 + +#define TIMER_DIV(freq, hz) (((freq) + (hz) / 2) / (hz)) + +#define PIT_8254_FREQ 1193182 +static const int nsecs_per_tick = 1000000000 / PIT_8254_FREQ; + +struct counter { + struct timeval tv; /* uptime when counter was loaded */ + uint16_t initial; /* initial counter value */ + uint8_t cr[2]; + uint8_t ol[2]; + int crbyte; + int olbyte; +}; + +static void +timevalfix(struct timeval *t1) +{ + + if (t1->tv_usec < 0) { + t1->tv_sec--; + t1->tv_usec += 1000000; + } + if (t1->tv_usec >= 1000000) { + t1->tv_sec++; + t1->tv_usec -= 1000000; + } +} + +static void +timevalsub(struct timeval *t1, const struct timeval *t2) +{ + + t1->tv_sec -= t2->tv_sec; + t1->tv_usec -= t2->tv_usec; + timevalfix(t1); +} + +static void +latch(struct counter *c) +{ + struct timeval tv2; + uint16_t lval; + uint64_t delta_nsecs, delta_ticks; + + /* cannot latch a new value until the old one has been consumed */ + if (c->olbyte != 0) + return; + + if (c->initial == 0 || c->initial == 1) { + /* + * XXX the program that runs the VM can be stopped and + * restarted at any time. This means that state that was + * created by the guest is destroyed between invocations + * of the program. + * + * If the counter's initial value is not programmed we + * assume a value that would be set to generate 'guest_hz' + * interrupts per second. + */ + c->initial = TIMER_DIV(PIT_8254_FREQ, guest_hz); + gettimeofday(&c->tv, NULL); + } + + (void)gettimeofday(&tv2, NULL); + timevalsub(&tv2, &c->tv); + delta_nsecs = tv2.tv_sec * 1000000000 + tv2.tv_usec * 1000; + delta_ticks = delta_nsecs / nsecs_per_tick; + + lval = c->initial - delta_ticks % c->initial; + c->olbyte = 2; + c->ol[1] = lval; /* LSB */ + c->ol[0] = lval >> 8; /* MSB */ +} + +static int +pit_8254_handler(struct vmctx *ctx, int vcpu, int in, int port, int bytes, + uint32_t *eax, void *arg) +{ + int sel, rw, mode; + uint8_t val; + struct counter *c; + + static struct counter counter[3]; + + if (bytes != 1) + return (-1); + + val = *eax; + + if (port == TIMER_MODE) { + assert(in == 0); + sel = val & TIMER_SEL_MASK; + rw = val & TIMER_RW_MASK; + mode = val & TIMER_MODE_MASK; + + if (sel == TIMER_SEL_READBACK) + return (-1); + if (rw != TIMER_LATCH && rw != TIMER_16BIT) + return (-1); + + if (rw != TIMER_LATCH) { + /* + * Counter mode is not affected when issuing a + * latch command. + */ + if (mode != TIMER_RATEGEN && mode != TIMER_SQWAVE) + return (-1); + } + + c = &counter[sel >> 6]; + if (rw == TIMER_LATCH) + latch(c); + else + c->olbyte = 0; /* reset latch after reprogramming */ + + return (0); + } + + /* counter ports */ + assert(port >= TIMER_CNTR0 && port <= TIMER_CNTR2); + c = &counter[port - TIMER_CNTR0]; + + if (in) { + /* + * XXX + * The spec says that once the output latch is completely + * read it should revert to "following" the counter. We don't + * do this because it is hard and any reasonable OS should + * always latch the counter before trying to read it. + */ + if (c->olbyte == 0) + c->olbyte = 2; + *eax = c->ol[--c->olbyte]; + } else { + c->cr[c->crbyte++] = *eax; + if (c->crbyte == 2) { + c->crbyte = 0; + c->initial = c->cr[0] | (uint16_t)c->cr[1] << 8; + if (c->initial == 0) + c->initial = 0xffff; + gettimeofday(&c->tv, NULL); + } + } + + return (0); +} + +INOUT_PORT(8254, TIMER_MODE, IOPORT_F_OUT, pit_8254_handler); +INOUT_PORT(8254, TIMER_CNTR0, IOPORT_F_INOUT, pit_8254_handler); +INOUT_PORT(8254, TIMER_CNTR1, IOPORT_F_INOUT, pit_8254_handler); +INOUT_PORT(8254, TIMER_CNTR2, IOPORT_F_INOUT, pit_8254_handler); |
