Currently the ptimer design uses a QEMU bottom-half as its mechanism for calling back into the device model using the ptimer when the timer has expired. Unfortunately this design is fatally flawed, because it means that there is a lag between the ptimer updating its own state and the device callback function updating device state, and guest accesses to device registers between the two can return inconsistent device state. We want to replace the bottom-half design with one where the guest device's callback is called either immediately (when the ptimer triggers by timeout) or when the device model code closes a transaction-begin/end section (when the ptimer triggers because the device model changed the ptimer's count value or other state). As the first step, rename ptimer_init() to ptimer_init_with_bh(), to free up the ptimer_init() name for the new API. We can then convert all the ptimer users away from ptimer_init_with_bh() before removing it entirely. (Commit created with git grep -l ptimer_init | xargs sed -i -e 's/ptimer_init/ptimer_init_with_bh/' and three overlong lines folded by hand.) Signed-off-by: Peter Maydell <peter.maydell@linaro.org> Reviewed-by: Richard Henderson <richard.henderson@linaro.org> Message-id: 20191008171740.9679-2-peter.maydell@linaro.org
245 lines
5.8 KiB
C
245 lines
5.8 KiB
C
/*
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* QEMU model of the LatticeMico32 timer block.
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*
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* Copyright (c) 2010 Michael Walle <michael@walle.cc>
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*
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* This library is free software; you can redistribute it and/or
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* modify it under the terms of the GNU Lesser General Public
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* License as published by the Free Software Foundation; either
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* version 2 of the License, or (at your option) any later version.
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*
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* This library is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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* Lesser General Public License for more details.
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*
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* You should have received a copy of the GNU Lesser General Public
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* License along with this library; if not, see <http://www.gnu.org/licenses/>.
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*
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*
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* Specification available at:
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* http://www.latticesemi.com/documents/mico32timer.pdf
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*/
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#include "qemu/osdep.h"
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#include "hw/irq.h"
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#include "hw/sysbus.h"
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#include "migration/vmstate.h"
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#include "trace.h"
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#include "qemu/timer.h"
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#include "hw/ptimer.h"
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#include "hw/qdev-properties.h"
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#include "qemu/error-report.h"
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#include "qemu/main-loop.h"
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#include "qemu/module.h"
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#define DEFAULT_FREQUENCY (50*1000000)
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enum {
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R_SR = 0,
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R_CR,
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R_PERIOD,
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R_SNAPSHOT,
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R_MAX
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};
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enum {
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SR_TO = (1 << 0),
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SR_RUN = (1 << 1),
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};
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enum {
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CR_ITO = (1 << 0),
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CR_CONT = (1 << 1),
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CR_START = (1 << 2),
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CR_STOP = (1 << 3),
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};
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#define TYPE_LM32_TIMER "lm32-timer"
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#define LM32_TIMER(obj) OBJECT_CHECK(LM32TimerState, (obj), TYPE_LM32_TIMER)
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struct LM32TimerState {
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SysBusDevice parent_obj;
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MemoryRegion iomem;
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QEMUBH *bh;
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ptimer_state *ptimer;
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qemu_irq irq;
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uint32_t freq_hz;
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uint32_t regs[R_MAX];
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};
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typedef struct LM32TimerState LM32TimerState;
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static void timer_update_irq(LM32TimerState *s)
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{
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int state = (s->regs[R_SR] & SR_TO) && (s->regs[R_CR] & CR_ITO);
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trace_lm32_timer_irq_state(state);
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qemu_set_irq(s->irq, state);
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}
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static uint64_t timer_read(void *opaque, hwaddr addr, unsigned size)
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{
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LM32TimerState *s = opaque;
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uint32_t r = 0;
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addr >>= 2;
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switch (addr) {
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case R_SR:
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case R_CR:
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case R_PERIOD:
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r = s->regs[addr];
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break;
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case R_SNAPSHOT:
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r = (uint32_t)ptimer_get_count(s->ptimer);
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break;
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default:
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error_report("lm32_timer: read access to unknown register 0x"
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TARGET_FMT_plx, addr << 2);
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break;
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}
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trace_lm32_timer_memory_read(addr << 2, r);
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return r;
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}
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static void timer_write(void *opaque, hwaddr addr,
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uint64_t value, unsigned size)
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{
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LM32TimerState *s = opaque;
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trace_lm32_timer_memory_write(addr, value);
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addr >>= 2;
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switch (addr) {
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case R_SR:
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s->regs[R_SR] &= ~SR_TO;
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break;
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case R_CR:
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s->regs[R_CR] = value;
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if (s->regs[R_CR] & CR_START) {
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ptimer_run(s->ptimer, 1);
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}
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if (s->regs[R_CR] & CR_STOP) {
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ptimer_stop(s->ptimer);
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}
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break;
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case R_PERIOD:
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s->regs[R_PERIOD] = value;
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ptimer_set_count(s->ptimer, value);
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break;
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case R_SNAPSHOT:
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error_report("lm32_timer: write access to read only register 0x"
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TARGET_FMT_plx, addr << 2);
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break;
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default:
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error_report("lm32_timer: write access to unknown register 0x"
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TARGET_FMT_plx, addr << 2);
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break;
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}
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timer_update_irq(s);
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}
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static const MemoryRegionOps timer_ops = {
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.read = timer_read,
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.write = timer_write,
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.endianness = DEVICE_NATIVE_ENDIAN,
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.valid = {
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.min_access_size = 4,
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.max_access_size = 4,
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},
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};
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static void timer_hit(void *opaque)
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{
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LM32TimerState *s = opaque;
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trace_lm32_timer_hit();
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s->regs[R_SR] |= SR_TO;
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if (s->regs[R_CR] & CR_CONT) {
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ptimer_set_count(s->ptimer, s->regs[R_PERIOD]);
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ptimer_run(s->ptimer, 1);
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}
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timer_update_irq(s);
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}
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static void timer_reset(DeviceState *d)
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{
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LM32TimerState *s = LM32_TIMER(d);
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int i;
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for (i = 0; i < R_MAX; i++) {
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s->regs[i] = 0;
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}
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ptimer_stop(s->ptimer);
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}
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static void lm32_timer_init(Object *obj)
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{
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LM32TimerState *s = LM32_TIMER(obj);
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SysBusDevice *dev = SYS_BUS_DEVICE(obj);
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sysbus_init_irq(dev, &s->irq);
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memory_region_init_io(&s->iomem, obj, &timer_ops, s,
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"timer", R_MAX * 4);
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sysbus_init_mmio(dev, &s->iomem);
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}
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static void lm32_timer_realize(DeviceState *dev, Error **errp)
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{
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LM32TimerState *s = LM32_TIMER(dev);
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s->bh = qemu_bh_new(timer_hit, s);
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s->ptimer = ptimer_init_with_bh(s->bh, PTIMER_POLICY_DEFAULT);
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ptimer_set_freq(s->ptimer, s->freq_hz);
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}
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static const VMStateDescription vmstate_lm32_timer = {
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.name = "lm32-timer",
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.version_id = 1,
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.minimum_version_id = 1,
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.fields = (VMStateField[]) {
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VMSTATE_PTIMER(ptimer, LM32TimerState),
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VMSTATE_UINT32(freq_hz, LM32TimerState),
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VMSTATE_UINT32_ARRAY(regs, LM32TimerState, R_MAX),
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VMSTATE_END_OF_LIST()
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}
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};
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static Property lm32_timer_properties[] = {
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DEFINE_PROP_UINT32("frequency", LM32TimerState, freq_hz, DEFAULT_FREQUENCY),
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DEFINE_PROP_END_OF_LIST(),
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};
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static void lm32_timer_class_init(ObjectClass *klass, void *data)
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{
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DeviceClass *dc = DEVICE_CLASS(klass);
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dc->realize = lm32_timer_realize;
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dc->reset = timer_reset;
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dc->vmsd = &vmstate_lm32_timer;
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dc->props = lm32_timer_properties;
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}
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static const TypeInfo lm32_timer_info = {
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.name = TYPE_LM32_TIMER,
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.parent = TYPE_SYS_BUS_DEVICE,
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.instance_size = sizeof(LM32TimerState),
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.instance_init = lm32_timer_init,
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.class_init = lm32_timer_class_init,
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};
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static void lm32_timer_register_types(void)
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{
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type_register_static(&lm32_timer_info);
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}
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type_init(lm32_timer_register_types)
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