aboutsummaryrefslogtreecommitdiff
path: root/hw/timer/i8254.c
diff options
context:
space:
mode:
Diffstat (limited to 'hw/timer/i8254.c')
-rw-r--r--hw/timer/i8254.c362
1 files changed, 362 insertions, 0 deletions
diff --git a/hw/timer/i8254.c b/hw/timer/i8254.c
new file mode 100644
index 0000000000..20c0c3601d
--- /dev/null
+++ b/hw/timer/i8254.c
@@ -0,0 +1,362 @@
+/*
+ * 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 "hw/hw.h"
+#include "hw/i386/pc.h"
+#include "hw/isa/isa.h"
+#include "qemu/timer.h"
+#include "hw/timer/i8254.h"
+#include "hw/timer/i8254_internal.h"
+
+//#define DEBUG_PIT
+
+#define RW_STATE_LSB 1
+#define RW_STATE_MSB 2
+#define RW_STATE_WORD0 3
+#define RW_STATE_WORD1 4
+
+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_ns(vm_clock) - s->count_load_time, PIT_FREQ,
+ get_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;
+}
+
+/* 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_get_clock_ns(vm_clock);
+ 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_get_clock_ns(vm_clock);
+ 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_get_clock_ns(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, 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_get_clock_ns(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 uint64_t pit_ioport_read(void *opaque, hwaddr addr,
+ unsigned size)
+{
+ PITCommonState *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 || 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) / get_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_reset(DeviceState *dev)
+{
+ PITCommonState *pit = DO_UPCAST(PITCommonState, dev.qdev, dev);
+ PITChannelState *s;
+
+ pit_reset_common(pit);
+
+ s = &pit->channels[0];
+ if (!s->irq_disabled) {
+ qemu_mod_timer(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_get_clock_ns(vm_clock));
+ } else {
+ s->irq_disabled = 1;
+ qemu_del_timer(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) {
+ qemu_mod_timer(sc->irq_timer, sc->next_transition_time);
+ } else {
+ qemu_del_timer(sc->irq_timer);
+ }
+}
+
+static int pit_initfn(PITCommonState *pit)
+{
+ PITChannelState *s;
+
+ s = &pit->channels[0];
+ /* the timer 0 is connected to an IRQ */
+ s->irq_timer = qemu_new_timer_ns(vm_clock, pit_irq_timer, s);
+ qdev_init_gpio_out(&pit->dev.qdev, &s->irq, 1);
+
+ memory_region_init_io(&pit->ioports, &pit_ioport_ops, pit, "pit", 4);
+
+ qdev_init_gpio_in(&pit->dev.qdev, pit_irq_control, 1);
+
+ return 0;
+}
+
+static Property pit_properties[] = {
+ DEFINE_PROP_HEX32("iobase", PITCommonState, iobase, -1),
+ DEFINE_PROP_END_OF_LIST(),
+};
+
+static void pit_class_initfn(ObjectClass *klass, void *data)
+{
+ PITCommonClass *k = PIT_COMMON_CLASS(klass);
+ DeviceClass *dc = DEVICE_CLASS(klass);
+
+ k->init = pit_initfn;
+ 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;
+ dc->props = pit_properties;
+}
+
+static const TypeInfo pit_info = {
+ .name = "isa-pit",
+ .parent = TYPE_PIT_COMMON,
+ .instance_size = sizeof(PITCommonState),
+ .class_init = pit_class_initfn,
+};
+
+static void pit_register_types(void)
+{
+ type_register_static(&pit_info);
+}
+
+type_init(pit_register_types)
generated by cgit v1.2.3 (git 2.26.2) at 2024-12-15 04:16:44 +0000