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qemu-e2k/hw/timer/i8254.c

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/*
* QEMU 8253/8254 interval timer emulation
*
* Copyright (c) 2003-2004 Fabrice Bellard
*
* Permission is hereby granted, free of charge, to any person obtaining a copy
* of this software and associated documentation files (the "Software"), to deal
* in the Software without restriction, including without limitation the rights
* to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
* copies of the Software, and to permit persons to whom the Software is
* furnished to do so, subject to the following conditions:
*
* The above copyright notice and this permission notice shall be included in
* all copies or substantial portions of the Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
* THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
* OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
* THE SOFTWARE.
*/
#include "qemu/osdep.h"
#include "hw/irq.h"
#include "qemu/module.h"
#include "qemu/timer.h"
#include "hw/timer/i8254.h"
#include "hw/timer/i8254_internal.h"
#include "qom/object.h"
//#define DEBUG_PIT
#define RW_STATE_LSB 1
#define RW_STATE_MSB 2
#define RW_STATE_WORD0 3
#define RW_STATE_WORD1 4
typedef struct PITClass PITClass;
DECLARE_CLASS_CHECKERS(PITClass, PIT,
TYPE_I8254)
struct PITClass {
PITCommonClass parent_class;
DeviceRealize parent_realize;
};
static void pit_irq_timer_update(PITChannelState *s, int64_t current_time);
static int pit_get_count(PITChannelState *s)
{
uint64_t d;
int counter;
d = muldiv64(qemu_clock_get_ns(QEMU_CLOCK_VIRTUAL) - s->count_load_time, PIT_FREQ,
NANOSECONDS_PER_SECOND);
switch(s->mode) {
case 0:
case 1:
case 4:
case 5:
counter = (s->count - d) & 0xffff;
break;
case 3:
/* XXX: may be incorrect for odd counts */
counter = s->count - ((2 * d) % s->count);
break;
default:
counter = s->count - (d % s->count);
break;
}
return counter;
}
/* val must be 0 or 1 */
static void pit_set_channel_gate(PITCommonState *s, PITChannelState *sc,
int val)
{
switch (sc->mode) {
default:
case 0:
case 4:
/* XXX: just disable/enable counting */
break;
case 1:
case 5:
if (sc->gate < val) {
/* restart counting on rising edge */
sc->count_load_time = qemu_clock_get_ns(QEMU_CLOCK_VIRTUAL);
pit_irq_timer_update(sc, sc->count_load_time);
}
break;
case 2:
case 3:
if (sc->gate < val) {
/* restart counting on rising edge */
sc->count_load_time = qemu_clock_get_ns(QEMU_CLOCK_VIRTUAL);
pit_irq_timer_update(sc, sc->count_load_time);
}
/* XXX: disable/enable counting */
break;
}
sc->gate = val;
}
static inline void pit_load_count(PITChannelState *s, int val)
{
if (val == 0)
val = 0x10000;
s->count_load_time = qemu_clock_get_ns(QEMU_CLOCK_VIRTUAL);
s->count = val;
pit_irq_timer_update(s, s->count_load_time);
}
/* if already latched, do not latch again */
static void pit_latch_count(PITChannelState *s)
{
if (!s->count_latched) {
s->latched_count = pit_get_count(s);
s->count_latched = s->rw_mode;
}
}
static void pit_ioport_write(void *opaque, hwaddr addr,
uint64_t val, unsigned size)
{
PITCommonState *pit = opaque;
int channel, access;
PITChannelState *s;
addr &= 3;
if (addr == 3) {
channel = val >> 6;
if (channel == 3) {
/* read back command */
for(channel = 0; channel < 3; channel++) {
s = &pit->channels[channel];
if (val & (2 << channel)) {
if (!(val & 0x20)) {
pit_latch_count(s);
}
if (!(val & 0x10) && !s->status_latched) {
/* status latch */
/* XXX: add BCD and null count */
s->status =
(pit_get_out(s,
qemu_clock_get_ns(QEMU_CLOCK_VIRTUAL)) << 7) |
(s->rw_mode << 4) |
(s->mode << 1) |
s->bcd;
s->status_latched = 1;
}
}
}
} else {
s = &pit->channels[channel];
access = (val >> 4) & 3;
if (access == 0) {
pit_latch_count(s);
} else {
s->rw_mode = access;
s->read_state = access;
s->write_state = access;
s->mode = (val >> 1) & 7;
s->bcd = val & 1;
/* XXX: update irq timer ? */
}
}
} else {
s = &pit->channels[addr];
switch(s->write_state) {
default:
case RW_STATE_LSB:
pit_load_count(s, val);
break;
case RW_STATE_MSB:
pit_load_count(s, val << 8);
break;
case RW_STATE_WORD0:
s->write_latch = val;
s->write_state = RW_STATE_WORD1;
break;
case RW_STATE_WORD1:
pit_load_count(s, s->write_latch | (val << 8));
s->write_state = RW_STATE_WORD0;
break;
}
}
}
static uint64_t pit_ioport_read(void *opaque, hwaddr addr,
unsigned size)
{
PITCommonState *pit = opaque;
int ret, count;
PITChannelState *s;
addr &= 3;
if (addr == 3) {
/* Mode/Command register is write only, read is ignored */
return 0;
}
s = &pit->channels[addr];
if (s->status_latched) {
s->status_latched = 0;
ret = s->status;
} else if (s->count_latched) {
switch(s->count_latched) {
default:
case RW_STATE_LSB:
ret = s->latched_count & 0xff;
s->count_latched = 0;
break;
case RW_STATE_MSB:
ret = s->latched_count >> 8;
s->count_latched = 0;
break;
case RW_STATE_WORD0:
ret = s->latched_count & 0xff;
s->count_latched = RW_STATE_MSB;
break;
}
} else {
switch(s->read_state) {
default:
case RW_STATE_LSB:
count = pit_get_count(s);
ret = count & 0xff;
break;
case RW_STATE_MSB:
count = pit_get_count(s);
ret = (count >> 8) & 0xff;
break;
case RW_STATE_WORD0:
count = pit_get_count(s);
ret = count & 0xff;
s->read_state = RW_STATE_WORD1;
break;
case RW_STATE_WORD1:
count = pit_get_count(s);
ret = (count >> 8) & 0xff;
s->read_state = RW_STATE_WORD0;
break;
}
}
return ret;
}
static void pit_irq_timer_update(PITChannelState *s, int64_t current_time)
{
int64_t expire_time;
int irq_level;
if (!s->irq_timer || s->irq_disabled) {
return;
}
expire_time = pit_get_next_transition_time(s, current_time);
irq_level = pit_get_out(s, current_time);
qemu_set_irq(s->irq, irq_level);
#ifdef DEBUG_PIT
printf("irq_level=%d next_delay=%f\n",
irq_level,
(double)(expire_time - current_time) / NANOSECONDS_PER_SECOND);
#endif
s->next_transition_time = expire_time;
if (expire_time != -1)
timer_mod(s->irq_timer, expire_time);
else
timer_del(s->irq_timer);
}
static void pit_irq_timer(void *opaque)
{
PITChannelState *s = opaque;
pit_irq_timer_update(s, s->next_transition_time);
}
static void pit_reset(DeviceState *dev)
{
PITCommonState *pit = PIT_COMMON(dev);
PITChannelState *s;
pit_reset_common(pit);
s = &pit->channels[0];
if (!s->irq_disabled) {
timer_mod(s->irq_timer, s->next_transition_time);
}
}
/* When HPET is operating in legacy mode, suppress the ignored timer IRQ,
* reenable it when legacy mode is left again. */
static void pit_irq_control(void *opaque, int n, int enable)
{
PITCommonState *pit = opaque;
PITChannelState *s = &pit->channels[0];
if (enable) {
s->irq_disabled = 0;
pit_irq_timer_update(s, qemu_clock_get_ns(QEMU_CLOCK_VIRTUAL));
} else {
s->irq_disabled = 1;
timer_del(s->irq_timer);
}
}
static const MemoryRegionOps pit_ioport_ops = {
.read = pit_ioport_read,
.write = pit_ioport_write,
.impl = {
.min_access_size = 1,
.max_access_size = 1,
},
.endianness = DEVICE_LITTLE_ENDIAN,
};
static void pit_post_load(PITCommonState *s)
{
PITChannelState *sc = &s->channels[0];
if (sc->next_transition_time != -1 && !sc->irq_disabled) {
timer_mod(sc->irq_timer, sc->next_transition_time);
} else {
timer_del(sc->irq_timer);
}
}
static void pit_realizefn(DeviceState *dev, Error **errp)
{
PITCommonState *pit = PIT_COMMON(dev);
PITClass *pc = PIT_GET_CLASS(dev);
PITChannelState *s;
s = &pit->channels[0];
/* the timer 0 is connected to an IRQ */
s->irq_timer = timer_new_ns(QEMU_CLOCK_VIRTUAL, pit_irq_timer, s);
qdev_init_gpio_out(dev, &s->irq, 1);
memory_region_init_io(&pit->ioports, OBJECT(pit), &pit_ioport_ops,
pit, "pit", 4);
qdev_init_gpio_in(dev, pit_irq_control, 1);
pc->parent_realize(dev, errp);
}
static Property pit_properties[] = {
DEFINE_PROP_UINT32("iobase", PITCommonState, iobase, -1),
DEFINE_PROP_END_OF_LIST(),
};
static void pit_class_initfn(ObjectClass *klass, void *data)
{
PITClass *pc = PIT_CLASS(klass);
PITCommonClass *k = PIT_COMMON_CLASS(klass);
DeviceClass *dc = DEVICE_CLASS(klass);
device_class_set_parent_realize(dc, pit_realizefn, &pc->parent_realize);
k->set_channel_gate = pit_set_channel_gate;
k->get_channel_info = pit_get_channel_info_common;
k->post_load = pit_post_load;
dc->reset = pit_reset;
device_class_set_props(dc, pit_properties);
}
static const TypeInfo pit_info = {
.name = TYPE_I8254,
.parent = TYPE_PIT_COMMON,
.instance_size = sizeof(PITCommonState),
.class_init = pit_class_initfn,
.class_size = sizeof(PITClass),
};
static void pit_register_types(void)
{
type_register_static(&pit_info);
}
type_init(pit_register_types)
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