Patchwork [1/4] i8254: Factor out base class for KVM reuse

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Submitter Jan Kiszka
Date Feb. 5, 2012, 10:46 a.m.
Message ID <5cf520a6908f505fdd84fb03ff227a7959ad484f.1328438750.git.jan.kiszka@web.de>
Download mbox | patch
Permalink /patch/139620/
State New
Headers show

Comments

Jan Kiszka - Feb. 5, 2012, 10:46 a.m.
From: Jan Kiszka <jan.kiszka@siemens.com>

Applying the concept used for the *PICs once again: establish a base
class for the i8254 that can be used both by the current user space
emulation and the upcoming KVM in-kernel version. We share most of the
public interface of the i8254, specifically to the pcspk, vmstate, reset
and certain init parts.

Signed-off-by: Jan Kiszka <jan.kiszka@siemens.com>
---
 Makefile.objs       |    2 +-
 hw/i8254.c          |  269 +++++---------------------------------------
 hw/i8254_common.c   |  307 +++++++++++++++++++++++++++++++++++++++++++++++++++
 hw/i8254_internal.h |   85 ++++++++++++++
 4 files changed, 424 insertions(+), 239 deletions(-)
 create mode 100644 hw/i8254_common.c
 create mode 100644 hw/i8254_internal.h

Patch

diff --git a/Makefile.objs b/Makefile.objs
index ec35320..15c3915 100644
--- a/Makefile.objs
+++ b/Makefile.objs
@@ -210,7 +210,7 @@  hw-obj-$(CONFIG_EMPTY_SLOT) += empty_slot.o
 
 hw-obj-$(CONFIG_SERIAL) += serial.o
 hw-obj-$(CONFIG_PARALLEL) += parallel.o
-hw-obj-$(CONFIG_I8254) += i8254.o
+hw-obj-$(CONFIG_I8254) += i8254_common.o i8254.o
 hw-obj-$(CONFIG_PCSPK) += pcspk.o
 hw-obj-$(CONFIG_PCKBD) += pckbd.o
 hw-obj-$(CONFIG_USB_UHCI) += usb-uhci.o
diff --git a/hw/i8254.c b/hw/i8254.c
index be39c55..f9f58e0 100644
--- a/hw/i8254.c
+++ b/hw/i8254.c
@@ -26,6 +26,7 @@ 
 #include "isa.h"
 #include "qemu-timer.h"
 #include "i8254.h"
+#include "i8254_internal.h"
 
 //#define DEBUG_PIT
 
@@ -34,34 +35,6 @@ 
 #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;
-    qemu_irq irq;
-    uint32_t irq_disabled;
-} PITChannelState;
-
-typedef struct PITState {
-    ISADevice dev;
-    MemoryRegion ioports;
-    uint32_t iobase;
-    PITChannelState channels[3];
-} PITState;
-
 static void pit_irq_timer_update(PITChannelState *s, int64_t current_time);
 
 static int pit_get_count(PITChannelState *s)
@@ -89,99 +62,11 @@  static int pit_get_count(PITChannelState *s)
     return counter;
 }
 
-/* get pit output bit */
-static int pit_get_out(PITChannelState *s, int64_t current_time)
-{
-    uint64_t d;
-    int out;
-
-    d = muldiv64(current_time - s->count_load_time, PIT_FREQ,
-                 get_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;
-}
-
-/* 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,
-                 get_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, get_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(ISADevice *dev, int channel, int val)
+static void pit_set_channel_gate(PITCommonState *s, PITChannelState *sc,
+                                 int val)
 {
-    PITState *pit = DO_UPCAST(PITState, dev, dev);
-    PITChannelState *s = &pit->channels[channel];
-
-    switch(s->mode) {
+    switch (sc->mode) {
     default:
     case 0:
     case 4:
@@ -189,34 +74,23 @@  void pit_set_gate(ISADevice *dev, int channel, int val)
         break;
     case 1:
     case 5:
-        if (s->gate < val) {
+        if (sc->gate < val) {
             /* restart counting on rising edge */
-            s->count_load_time = qemu_get_clock_ns(vm_clock);
-            pit_irq_timer_update(s, s->count_load_time);
+            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 (s->gate < val) {
+        if (sc->gate < val) {
             /* restart counting on rising edge */
-            s->count_load_time = qemu_get_clock_ns(vm_clock);
-            pit_irq_timer_update(s, s->count_load_time);
+            sc->count_load_time = qemu_get_clock_ns(vm_clock);
+            pit_irq_timer_update(sc, sc->count_load_time);
         }
         /* XXX: disable/enable counting */
         break;
     }
-    s->gate = val;
-}
-
-void pit_get_channel_info(ISADevice *dev, int channel, PITChannelInfo *info)
-{
-    PITState *pit = DO_UPCAST(PITState, dev, dev);
-    PITChannelState *s = &pit->channels[channel];
-
-    info->gate = s->gate;
-    info->mode = s->mode;
-    info->initial_count = s->count;
-    info->out = pit_get_out(s, qemu_get_clock_ns(vm_clock));
+    sc->gate = val;
 }
 
 static inline void pit_load_count(PITChannelState *s, int val)
@@ -239,7 +113,7 @@  static void pit_latch_count(PITChannelState *s)
 
 static void pit_ioport_write(void *opaque, uint32_t addr, uint32_t val)
 {
-    PITState *pit = opaque;
+    PITCommonState *pit = opaque;
     int channel, access;
     PITChannelState *s;
 
@@ -306,7 +180,7 @@  static void pit_ioport_write(void *opaque, uint32_t addr, uint32_t val)
 
 static uint32_t pit_ioport_read(void *opaque, uint32_t addr)
 {
-    PITState *pit = opaque;
+    PITCommonState *pit = opaque;
     int ret, count;
     PITChannelState *s;
 
@@ -387,94 +261,16 @@  static void pit_irq_timer(void *opaque)
     pit_irq_timer_update(s, s->next_transition_time);
 }
 
-static const VMStateDescription vmstate_pit_channel = {
-    .name = "pit channel",
-    .version_id = 2,
-    .minimum_version_id = 2,
-    .minimum_version_id_old = 2,
-    .fields      = (VMStateField []) {
-        VMSTATE_INT32(count, PITChannelState),
-        VMSTATE_UINT16(latched_count, PITChannelState),
-        VMSTATE_UINT8(count_latched, PITChannelState),
-        VMSTATE_UINT8(status_latched, PITChannelState),
-        VMSTATE_UINT8(status, PITChannelState),
-        VMSTATE_UINT8(read_state, PITChannelState),
-        VMSTATE_UINT8(write_state, PITChannelState),
-        VMSTATE_UINT8(write_latch, PITChannelState),
-        VMSTATE_UINT8(rw_mode, PITChannelState),
-        VMSTATE_UINT8(mode, PITChannelState),
-        VMSTATE_UINT8(bcd, PITChannelState),
-        VMSTATE_UINT8(gate, PITChannelState),
-        VMSTATE_INT64(count_load_time, PITChannelState),
-        VMSTATE_INT64(next_transition_time, PITChannelState),
-        VMSTATE_END_OF_LIST()
-    }
-};
-
-static int pit_load_old(QEMUFile *f, void *opaque, int version_id)
+static void pit_reset(DeviceState *dev)
 {
-    PITState *pit = opaque;
+    PITCommonState *pit = DO_UPCAST(PITCommonState, dev.qdev, dev);
     PITChannelState *s;
-    int i;
-
-    if (version_id != 1)
-        return -EINVAL;
-
-    for(i = 0; i < 3; i++) {
-        s = &pit->channels[i];
-        s->count=qemu_get_be32(f);
-        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);
-        s->count_load_time=qemu_get_be64(f);
-        s->irq_disabled = 0;
-        if (s->irq_timer) {
-            s->next_transition_time=qemu_get_be64(f);
-            qemu_get_timer(f, s->irq_timer);
-        }
-    }
-    return 0;
-}
 
-static const VMStateDescription vmstate_pit = {
-    .name = "i8254",
-    .version_id = 3,
-    .minimum_version_id = 2,
-    .minimum_version_id_old = 1,
-    .load_state_old = pit_load_old,
-    .fields      = (VMStateField []) {
-        VMSTATE_UINT32_V(channels[0].irq_disabled, PITState, 3),
-        VMSTATE_STRUCT_ARRAY(channels, PITState, 3, 2, vmstate_pit_channel, PITChannelState),
-        VMSTATE_TIMER(channels[0].irq_timer, PITState),
-        VMSTATE_END_OF_LIST()
-    }
-};
+    pit_reset_common(pit);
 
-static void pit_reset(DeviceState *dev)
-{
-    PITState *pit = container_of(dev, PITState, dev.qdev);
-    PITChannelState *s;
-    int i;
-
-    for(i = 0;i < 3; i++) {
-        s = &pit->channels[i];
-        s->mode = 3;
-        s->gate = (i != 2);
-        s->count_load_time = qemu_get_clock_ns(vm_clock);
-        s->count = 0x10000;
-        if (i == 0 && !s->irq_disabled) {
-            s->next_transition_time =
-                pit_get_next_transition_time(s, s->count_load_time);
-            qemu_mod_timer(s->irq_timer, s->next_transition_time);
-        }
+    s = &pit->channels[0];
+    if (!s->irq_disabled) {
+        qemu_mod_timer(s->irq_timer, s->next_transition_time);
     }
 }
 
@@ -482,7 +278,7 @@  static void pit_reset(DeviceState *dev)
  * reenable it when legacy mode is left again. */
 static void pit_irq_control(void *opaque, int n, int enable)
 {
-    PITState *pit = opaque;
+    PITCommonState *pit = opaque;
     PITChannelState *s = &pit->channels[0];
 
     if (enable) {
@@ -504,46 +300,43 @@  static const MemoryRegionOps pit_ioport_ops = {
     .old_portio = pit_portio
 };
 
-static int pit_initfn(ISADevice *dev)
+static int pit_initfn(PITCommonState *pit)
 {
-    PITState *pit = DO_UPCAST(PITState, dev, dev);
     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(&dev->qdev, &s->irq, 1);
+    qdev_init_gpio_out(&pit->dev.qdev, &s->irq, 1);
 
     memory_region_init_io(&pit->ioports, &pit_ioport_ops, pit, "pit", 4);
-    isa_register_ioport(dev, &pit->ioports, pit->iobase);
-
-    qdev_init_gpio_in(&dev->qdev, pit_irq_control, 1);
 
-    qdev_set_legacy_instance_id(&dev->qdev, pit->iobase, 2);
+    qdev_init_gpio_in(&pit->dev.qdev, pit_irq_control, 1);
 
     return 0;
 }
 
 static Property pit_properties[] = {
-    DEFINE_PROP_HEX32("iobase", PITState, iobase,  -1),
+    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);
-    ISADeviceClass *ic = ISA_DEVICE_CLASS(klass);
-    ic->init = pit_initfn;
-    dc->no_user = 1;
+
+    k->init = pit_initfn;
+    k->set_channel_gate = pit_set_channel_gate;
+    k->get_channel_info = pit_get_channel_info_common;
     dc->reset = pit_reset;
-    dc->vmsd = &vmstate_pit;
     dc->props = pit_properties;
 }
 
 static TypeInfo pit_info = {
     .name          = "isa-pit",
-    .parent        = TYPE_ISA_DEVICE,
-    .instance_size = sizeof(PITState),
+    .parent        = TYPE_PIT_COMMON,
+    .instance_size = sizeof(PITCommonState),
     .class_init    = pit_class_initfn,
 };
 
diff --git a/hw/i8254_common.c b/hw/i8254_common.c
new file mode 100644
index 0000000..0601d88
--- /dev/null
+++ b/hw/i8254_common.c
@@ -0,0 +1,307 @@ 
+/*
+ * QEMU 8253/8254 - common bits of emulated and KVM kernel model
+ *
+ * Copyright (c) 2003-2004 Fabrice Bellard
+ * Copyright (c) 2012      Jan Kiszka, Siemens AG
+ *
+ * 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.h"
+#include "pc.h"
+#include "isa.h"
+#include "qemu-timer.h"
+#include "i8254.h"
+#include "i8254_internal.h"
+
+/* val must be 0 or 1 */
+void pit_set_gate(ISADevice *dev, int channel, int val)
+{
+    PITCommonState *pit = PIT_COMMON(dev);
+    PITChannelState *s = &pit->channels[channel];
+    PITCommonClass *c = PIT_COMMON_GET_CLASS(pit);
+
+    c->set_channel_gate(pit, s, val);
+}
+
+/* get pit output bit */
+int pit_get_out(PITChannelState *s, int64_t current_time)
+{
+    uint64_t d;
+    int out;
+
+    d = muldiv64(current_time - s->count_load_time, PIT_FREQ,
+                 get_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;
+}
+
+/* return -1 if no transition will occur.  */
+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,
+                 get_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, get_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;
+}
+
+void pit_get_channel_info_common(PITCommonState *s, PITChannelState *sc,
+                                 PITChannelInfo *info)
+{
+    info->gate = sc->gate;
+    info->mode = sc->mode;
+    info->initial_count = sc->count;
+    info->out = pit_get_out(sc, qemu_get_clock_ns(vm_clock));
+}
+
+void pit_get_channel_info(ISADevice *dev, int channel, PITChannelInfo *info)
+{
+    PITCommonState *pit = PIT_COMMON(dev);
+    PITChannelState *s = &pit->channels[channel];
+    PITCommonClass *c = PIT_COMMON_GET_CLASS(pit);
+
+    c->get_channel_info(pit, s, info);
+}
+
+void pit_reset_common(PITCommonState *pit)
+{
+    PITChannelState *s;
+    int i;
+
+    for (i = 0; i < 3; i++) {
+        s = &pit->channels[i];
+        s->mode = 3;
+        s->gate = (i != 2);
+        s->count_load_time = qemu_get_clock_ns(vm_clock);
+        s->count = 0x10000;
+        if (i == 0 && !s->irq_disabled) {
+            s->next_transition_time =
+                pit_get_next_transition_time(s, s->count_load_time);
+        }
+    }
+}
+
+static int pit_init_common(ISADevice *dev)
+{
+    PITCommonState *pit = PIT_COMMON(dev);
+    PITCommonClass *c = PIT_COMMON_GET_CLASS(pit);
+    int ret;
+
+    ret = c->init(pit);
+    if (ret < 0) {
+        return ret;
+    }
+
+    isa_register_ioport(dev, &pit->ioports, pit->iobase);
+
+    qdev_set_legacy_instance_id(&dev->qdev, pit->iobase, 2);
+
+    return 0;
+}
+
+static const VMStateDescription vmstate_pit_channel = {
+    .name = "pit channel",
+    .version_id = 2,
+    .minimum_version_id = 2,
+    .minimum_version_id_old = 2,
+    .fields = (VMStateField[]) {
+        VMSTATE_INT32(count, PITChannelState),
+        VMSTATE_UINT16(latched_count, PITChannelState),
+        VMSTATE_UINT8(count_latched, PITChannelState),
+        VMSTATE_UINT8(status_latched, PITChannelState),
+        VMSTATE_UINT8(status, PITChannelState),
+        VMSTATE_UINT8(read_state, PITChannelState),
+        VMSTATE_UINT8(write_state, PITChannelState),
+        VMSTATE_UINT8(write_latch, PITChannelState),
+        VMSTATE_UINT8(rw_mode, PITChannelState),
+        VMSTATE_UINT8(mode, PITChannelState),
+        VMSTATE_UINT8(bcd, PITChannelState),
+        VMSTATE_UINT8(gate, PITChannelState),
+        VMSTATE_INT64(count_load_time, PITChannelState),
+        VMSTATE_INT64(next_transition_time, PITChannelState),
+        VMSTATE_END_OF_LIST()
+    }
+};
+
+static int pit_load_old(QEMUFile *f, void *opaque, int version_id)
+{
+    PITCommonState *pit = opaque;
+    PITChannelState *s;
+    int i;
+
+    if (version_id != 1) {
+        return -EINVAL;
+    }
+
+    for (i = 0; i < 3; i++) {
+        s = &pit->channels[i];
+        s->count = qemu_get_be32(f);
+        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);
+        s->count_load_time = qemu_get_be64(f);
+        s->irq_disabled = 0;
+        if (s->irq_timer) {
+            s->next_transition_time = qemu_get_be64(f);
+            qemu_get_timer(f, s->irq_timer);
+        }
+    }
+    return 0;
+}
+
+static void pit_dispatch_pre_save(void *opaque)
+{
+    PITCommonState *s = opaque;
+    PITCommonClass *c = PIT_COMMON_GET_CLASS(s);
+
+    if (c->pre_save) {
+        c->pre_save(s);
+    }
+}
+
+static int pit_dispatch_post_load(void *opaque, int version_id)
+{
+    PITCommonState *s = opaque;
+    PITCommonClass *c = PIT_COMMON_GET_CLASS(s);
+
+    if (c->post_load) {
+        c->post_load(s);
+    }
+    return 0;
+}
+
+static const VMStateDescription vmstate_pit_common = {
+    .name = "i8254",
+    .version_id = 3,
+    .minimum_version_id = 2,
+    .minimum_version_id_old = 1,
+    .load_state_old = pit_load_old,
+    .pre_save = pit_dispatch_pre_save,
+    .post_load = pit_dispatch_post_load,
+    .fields = (VMStateField[]) {
+        VMSTATE_UINT32_V(channels[0].irq_disabled, PITCommonState, 3),
+        VMSTATE_STRUCT_ARRAY(channels, PITCommonState, 3, 2,
+                             vmstate_pit_channel, PITChannelState),
+        VMSTATE_TIMER(channels[0].irq_timer, PITCommonState),
+        VMSTATE_END_OF_LIST()
+    }
+};
+
+static void pit_common_class_init(ObjectClass *klass, void *data)
+{
+    ISADeviceClass *ic = ISA_DEVICE_CLASS(klass);
+    DeviceClass *dc = DEVICE_CLASS(klass);
+
+    ic->init = pit_init_common;
+    dc->vmsd = &vmstate_pit_common;
+    dc->no_user = 1;
+}
+
+static TypeInfo pit_common_type = {
+    .name          = TYPE_PIT_COMMON,
+    .parent        = TYPE_ISA_DEVICE,
+    .instance_size = sizeof(PITCommonState),
+    .class_size    = sizeof(PITCommonClass),
+    .class_init    = pit_common_class_init,
+    .abstract      = true,
+};
+
+static void register_devices(void)
+{
+    type_register_static(&pit_common_type);
+}
+
+device_init(register_devices);
diff --git a/hw/i8254_internal.h b/hw/i8254_internal.h
new file mode 100644
index 0000000..686f0c2
--- /dev/null
+++ b/hw/i8254_internal.h
@@ -0,0 +1,85 @@ 
+/*
+ * QEMU 8253/8254 - internal interfaces
+ *
+ * Copyright (c) 2011 Jan Kiszka, Siemens AG
+ *
+ * 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.
+ */
+
+#ifndef QEMU_I8254_INTERNAL_H
+#define QEMU_I8254_INTERNAL_H
+
+#include "hw.h"
+#include "pc.h"
+#include "isa.h"
+
+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;
+    qemu_irq irq;
+    uint32_t irq_disabled;
+} PITChannelState;
+
+typedef struct PITCommonState {
+    ISADevice dev;
+    MemoryRegion ioports;
+    uint32_t iobase;
+    PITChannelState channels[3];
+} PITCommonState;
+
+#define TYPE_PIT_COMMON "pit-common"
+#define PIT_COMMON(obj) \
+     OBJECT_CHECK(PITCommonState, (obj), TYPE_PIT_COMMON)
+#define PIT_COMMON_CLASS(klass) \
+     OBJECT_CLASS_CHECK(PITCommonClass, (klass), TYPE_PIT_COMMON)
+#define PIT_COMMON_GET_CLASS(obj) \
+     OBJECT_GET_CLASS(PITCommonClass, (obj), TYPE_PIT_COMMON)
+
+typedef struct PITCommonClass {
+    ISADeviceClass parent_class;
+
+    int (*init)(PITCommonState *s);
+    void (*set_channel_gate)(PITCommonState *s, PITChannelState *sc, int val);
+    void (*get_channel_info)(PITCommonState *s, PITChannelState *sc,
+                             PITChannelInfo *info);
+    void (*pre_save)(PITCommonState *s);
+    void (*post_load)(PITCommonState *s);
+} PITCommonClass;
+
+int pit_get_out(PITChannelState *s, int64_t current_time);
+int64_t pit_get_next_transition_time(PITChannelState *s, int64_t current_time);
+void pit_get_channel_info_common(PITCommonState *s, PITChannelState *sc,
+                                 PITChannelInfo *info);
+void pit_reset_common(PITCommonState *s);
+
+#endif /* !QEMU_I8254_INTERNAL_H */