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/* $OpenBSD: i8253.c,v 1.3 2016/10/03 06:00:17 mlarkin Exp $ */
/*
* Copyright (c) 2016 Mike Larkin <mlarkin@openbsd.org>
*
* Permission to use, copy, modify, and distribute this software for any
* purpose with or without fee is hereby granted, provided that the above
* copyright notice and this permission notice appear in all copies.
*
* THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
* WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
* MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
* ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
* WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
* ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
* OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
*/
#include <sys/time.h>
#include <sys/types.h>
#include <dev/ic/i8253reg.h>
#include <machine/vmmvar.h>
#include <event.h>
#include <string.h>
#include <stddef.h>
#include "i8253.h"
#include "proc.h"
#include "vmm.h"
extern char *__progname;
/*
* Counter 0 is used to generate the legacy hardclock interrupt (HZ).
* Counters 1 and 2 are not connected to any output (although someone
* could hook counter 2 up to an emulated pcppi(4) at some point).
*/
struct i8253_counter i8253_counter[3];
/*
* i8253_init
*
* Initialize the emulated i8253 PIT.
*
* Parameters:
* vm_id: vmm(4)-assigned ID of the VM
*/
void
i8253_init(uint32_t vm_id)
{
memset(&i8253_counter, 0, sizeof(struct i8253_counter));
gettimeofday(&i8253_counter[0].tv, NULL);
i8253_counter[0].start = 0xFFFF;
i8253_counter[0].mode = TIMER_RATEGEN;
evtimer_set(&i8253_counter[0].timer, i8253_fire,
(void *)(uint64_t)vm_id);
i8253_reset(0);
}
/*
* vcpu_exit_i8253
*
* Handles emulated i8253 PIT access (in/out instruction to PIT ports).
* We don't emulate all the modes of the i8253, just the basic squarewave
* "rategen" clock.
*
* Parameters:
* vrp: vm run parameters containing exit information for the I/O
* instruction being performed
*
* Return value:
* Interrupt to inject to the guest VM, or 0xFF if no interrupt should
* be injected.
*/
uint8_t
vcpu_exit_i8253(struct vm_run_params *vrp)
{
uint32_t out_data;
uint8_t sel, rw, data, mode;
uint64_t ns, ticks;
struct timeval now, delta;
union vm_exit *vei = vrp->vrp_exit;
if (vei->vei.vei_port == TIMER_CTRL) {
if (vei->vei.vei_dir == VEI_DIR_OUT) { /* OUT instruction */
out_data = vei->vei.vei_data;
sel = out_data &
(TIMER_SEL0 | TIMER_SEL1 | TIMER_SEL2);
sel = sel >> 6;
if (sel > 2) {
log_warnx("%s: i8253 PIT: unuspported "
"counter selected (%d)",
__progname, sel);
goto ret;
}
rw = vei->vei.vei_data & (TIMER_LATCH | TIMER_16BIT);
/*
* Since we don't truly emulate each tick of the PIT
* counter, when the guest asks for the timer to be
* latched, simulate what the counter would have been
* had we performed full emulation. We do this by
* calculating when the counter was reset vs how much
* time has elapsed, then bias by the counter tick
* rate.
*/
if (rw == TIMER_LATCH) {
gettimeofday(&now, NULL);
delta.tv_sec = now.tv_sec -
i8253_counter[sel].tv.tv_sec;
delta.tv_usec = now.tv_usec -
i8253_counter[sel].tv.tv_usec;
if (delta.tv_usec < 0) {
delta.tv_sec--;
delta.tv_usec += 1000000;
}
if (delta.tv_usec > 1000000) {
delta.tv_sec++;
delta.tv_usec -= 1000000;
}
ns = delta.tv_usec * 1000 +
delta.tv_sec * 1000000000;
ticks = ns / NS_PER_TICK;
i8253_counter[sel].olatch =
i8253_counter[sel].start -
ticks % i8253_counter[sel].start;
goto ret;
} else if (rw != TIMER_16BIT) {
log_warnx("%s: i8253 PIT: unsupported counter "
"%d rw mode 0x%x selected", __func__,
sel, (rw & TIMER_16BIT));
}
goto ret;
} else {
log_warnx("%s: i8253 PIT: read from control port "
"unsupported", __progname);
vei->vei.vei_data = 0;
}
} else {
sel = vei->vei.vei_port - (TIMER_CNTR0 + TIMER_BASE);
if (sel != 0) {
log_warnx("%s: i8253 PIT: nonzero channel %d "
"selected", __func__, sel);
}
if (vei->vei.vei_dir == VEI_DIR_OUT) { /* OUT instruction */
if (i8253_counter[sel].last_w == 0) {
out_data = vei->vei.vei_data;
i8253_counter[sel].ilatch |= (out_data & 0xff);
i8253_counter[sel].last_w = 1;
} else {
out_data = vei->vei.vei_data;
i8253_counter[sel].ilatch |= ((out_data & 0xff) << 8);
i8253_counter[sel].start =
i8253_counter[sel].ilatch;
i8253_counter[sel].last_w = 0;
mode = out_data & 0xe;
i8253_counter[sel].mode = mode;
i8253_reset(sel);
}
} else {
if (i8253_counter[sel].last_r == 0) {
data = i8253_counter[sel].olatch >> 8;
vei->vei.vei_data = data;
i8253_counter[sel].last_w = 1;
} else {
data = i8253_counter[sel].olatch & 0xFF;
vei->vei.vei_data = data;
i8253_counter[sel].last_w = 0;
}
}
}
ret:
return (0xFF);
}
/*
* i8253_reset
*
* Resets the i8253's counter timer
*
* Parameters:
* chn: counter ID. Only channel ID 0 is presently emulated.
*/
void
i8253_reset(uint8_t chn)
{
struct timeval tv;
if (chn != 0) {
/*
* Channels other than 0 are not likely to be programmed
* by the guest. Long ago, channel 1 was used to refresh
* RAM, and channel 2 is sometimes routed to the PC
* speaker.
*/
log_debug("%s: unsupported channel %d start request",
__func__, chn);
return;
}
if (i8253_counter[chn].mode != TIMER_RATEGEN &&
i8253_counter[chn].mode != (TIMER_RATEGEN | 0x8)) {
log_warnx("%s: unsupported counter mode 0x%x",
__func__, i8253_counter[chn].mode);
return;
}
evtimer_del(&i8253_counter[chn].timer);
timerclear(&tv);
tv.tv_usec = (i8253_counter[chn].start * NS_PER_TICK) / 1000;
evtimer_add(&i8253_counter[chn].timer, &tv);
}
/*
* i8253_fire
*
* Callback invoked when the 8253 PIT timer fires. This will assert
* IRQ0 on the legacy PIC attached to VCPU0.
*
* Parameters:
* fd: unused
* type: unused
* arg: VM ID
*/
void
i8253_fire(int fd, short type, void *arg)
{
struct timeval tv;
timerclear(&tv);
tv.tv_usec = (i8253_counter[0].start * NS_PER_TICK) / 1000;
vcpu_assert_pic_irq((ptrdiff_t)arg, 0, 0);
evtimer_add(&i8253_counter[0].timer, &tv);
}
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