/*
* 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 "vl.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 PITChannelState {
int count; /* can be 65536 */
uint16_t latched_count;
uint8_t count_latched;
uint8_t status_latched;
uint8_t status;
uint8_t read_state;
uint8_t write_state;
uint8_t write_latch;
uint8_t rw_mode;
uint8_t mode;
uint8_t bcd; /* not supported */
uint8_t gate; /* timer start */
int64_t count_load_time;
/* irq handling */
int64_t next_transition_time;
QEMUTimer *irq_timer;
int irq;
} PITChannelState;
struct PITState {
PITChannelState channels[3];
};
static PITState pit_state;
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_get_clock(vm_clock) - s->count_load_time, PIT_FREQ, ticks_per_sec);
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;
}
/* get pit output bit */
static int pit_get_out1(PITChannelState *s, int64_t current_time)
{
uint64_t d;
int out;
d = muldiv64(current_time - s->count_load_time, PIT_FREQ, ticks_per_sec);
switch(s->mode) {
default:
case 0:
out = (d >= s->count);
break;
case 1:
out = (d < s->count);
break;
case 2:
if ((d % s->count) == 0 && d != 0)
out = 1;
else
out = 0;
break;
case 3:
out = (d % s->count) < ((s->count + 1) >> 1);
break;
case 4:
case 5:
out = (d == s->count);
break;
}
return out;
}
int pit_get_out(PITState *pit, int channel, int64_t current_time)
{
PITChannelState *s = &pit->channels[channel];
return pit_get_out1(s, current_time);
}
/* return -1 if no transition will occur. */
static int64_t pit_get_next_transition_time(PITChannelState *s,
int64_t current_time)
{
uint64_t d, next_time, base;
int period2;
d = muldiv64(current_time - s->count_load_time, PIT_FREQ, ticks_per_sec);
switch(s->mode) {
default:
case 0:
case 1:
if (d < s->count)
next_time = s->count;
else
return -1;
break;
case 2:
base = (d / s->count) * s->count;
if ((d - base) == 0 && d != 0)
next_time = base + s->count;
else
next_time = base + s->count + 1;
break;
case 3:
base = (d / s->count) * s->count;
period2 = ((s->count + 1) >> 1);
if ((d - base) < period2)
next_time = base + period2;
else
next_time = base + s->count;
break;
case 4:
case 5:
if (d < s->count)
next_time = s->count;
else if (d == s->count)
next_time = s->count + 1;
else
return -1;
break;
}
/* convert to timer units */
next_time = s->count_load_time + muldiv64(next_time, ticks_per_sec, PIT_FREQ);
/* fix potential rounding problems */
/* XXX: better solution: use a clock at PIT_FREQ Hz */
if (next_time <= current_time)
next_time = current_time + 1;
return next_time;
}
/* val must be 0 or 1 */
void pit_set_gate(PITState *pit, int channel, int val)
{
PITChannelState *s = &pit->channels[channel];
switch(s->mode) {
default:
case 0:
case 4:
/* XXX: just disable/enable counting */
break;
case 1:
case 5:
if (s->gate < val) {
/* restart counting on rising edge */
s->count_load_time = qemu_get_clock(vm_clock);
pit_irq_timer_update(s, s->count_load_time);
}
break;
case 2:
case 3:
if (s->gate < val) {
/* restart counting on rising edge */
s->count_load_time = qemu_get_clock(vm_clock);
pit_irq_timer_update(s, s->count_load_time);
}
/* XXX: disable/enable counting */
break;
}
s->gate = val;
}
int pit_get_gate(PITState *pit, int channel)
{
PITChannelState *s = &pit->channels[channel];
return s->gate;
}
int pit_get_initial_count(PITState *pit, int channel)
{
PITChannelState *s = &pit->channels[channel];
return s->count;
}
int pit_get_mode(PITState *pit, int channel)
{
PITChannelState *s = &pit->channels[channel];
return s->mode;
}
static inline void pit_load_count(PITChannelState *s, int val)
{
if (val == 0)
val = 0x10000;
s->count_load_time = qemu_get_clock(vm_clock);
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, uint32_t addr, uint32_t val)
{
PITState *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_out1(s, qemu_get_clock(vm_clock)) << 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 uint32_t pit_ioport_read(void *opaque, uint32_t addr)
{
PITState *pit = opaque;
int ret, count;
PITChannelState *s;
addr &= 3;
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)
return;
expire_time = pit_get_next_transition_time(s, current_time);
irq_level = pit_get_out1(s, current_time);
pic_set_irq(s->irq, irq_level);
#ifdef DEBUG_PIT
printf("irq_level=%d next_delay=%f\n",
irq_level,
(double)(expire_time - current_time) / ticks_per_sec);
#endif
s->next_transition_time = expire_time;
if (expire_time != -1)
qemu_mod_timer(s->irq_timer, expire_time);
else
qemu_del_timer(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_save(QEMUFile *f, void *opaque)
{
PITState *pit = opaque;
PITChannelState *s;
int i;
for(i = 0; i < 3; i++) {
s = &pit->channels[i];
qemu_put_be32s(f, &s->count);
qemu_put_be16s(f, &s->latched_count);
qemu_put_8s(f, &s->count_latched);
qemu_put_8s(f, &s->status_latched);
qemu_put_8s(f, &s->status);
qemu_put_8s(f, &s->read_state);
qemu_put_8s(f, &s->write_state);
qemu_put_8s(f, &s->write_latch);
qemu_put_8s(f, &s->rw_mode);
qemu_put_8s(f, &s->mode);
qemu_put_8s(f, &s->bcd);
qemu_put_8s(f, &s->gate);
qemu_put_be64s(f, &s->count_load_time);
if (s->irq_timer) {
qemu_put_be64s(f, &s->next_transition_time);
qemu_put_timer(f, s->irq_timer);
}
}
}
static int pit_load(QEMUFile *f, void *opaque, int version_id)
{
PITState *pit = opaque;
PITChannelState *s;
int i;
if (version_id != 1)
return -EINVAL;
for(i = 0; i < 3; i++) {
s = &pit->channels[i];
qemu_get_be32s(f, &s->count);
qemu_get_be16s(f, &s->latched_count);
qemu_get_8s(f, &s->count_latched);
qemu_get_8s(f, &s->status_latched);
qemu_get_8s(f, &s->status);
qemu_get_8s(f, &s->read_state);
qemu_get_8s(f, &s->write_state);
qemu_get_8s(f, &s->write_latch);
qemu_get_8s(f, &s->rw_mode);
qemu_get_8s(f, &s->mode);
qemu_get_8s(f, &s->bcd);
qemu_get_8s(f, &s->gate);
qemu_get_be64s(f, &s->count_load_time);
if (s->irq_timer) {
qemu_get_be64s(f, &s->next_transition_time);
qemu_get_timer(f, s->irq_timer);
}
}
return 0;
}
static void pit_reset(void *opaque)
{
PITState *pit = opaque;
PITChannelState *s;
int i;
for(i = 0;i < 3; i++) {
s = &pit->channels[i];
s->mode = 3;
s->gate = (i != 2);
pit_load_count(s, 0);
}
}
PITState *pit_init(int base, int irq)
{
PITState *pit = &pit_state;
PITChannelState *s;
s = &pit->channels[0];
/* the timer 0 is connected to an IRQ */
s->irq_timer = qemu_new_timer(vm_clock, pit_irq_timer, s);
s->irq = irq;
register_savevm("i8254", base, 1, pit_save, pit_load, pit);
qemu_register_reset(pit_reset, pit);
register_ioport_write(base, 4, 1, pit_ioport_write, pit);
register_ioport_read(base, 3, 1, pit_ioport_read, pit);
pit_reset(pit);
return pit;
}
