diff mbox series

[v6,1/3] hw: rtc: Add Goldfish RTC device

Message ID 20191103075353.86497-2-anup.patel@wdc.com (mailing list archive)
State New, archived
Headers show
Series RTC support for QEMU RISC-V virt machine | expand

Commit Message

Anup Patel Nov. 3, 2019, 7:55 a.m. UTC
This patch adds model for Google Goldfish virtual platform RTC device.

We will be adding Goldfish RTC device to the QEMU RISC-V virt machine
for providing real date-time to Guest Linux. The corresponding Linux
driver for Goldfish RTC device is already available in upstream Linux.

For now, VM migration support is available but untested for Goldfish RTC
device. It will be hardened in-future when we implement VM migration for
KVM RISC-V.

Signed-off-by: Anup Patel <anup.patel@wdc.com>
Reviewed-by: Alistair Francis <alistair.francis@wdc.com>
---
 hw/rtc/Kconfig                |   3 +
 hw/rtc/Makefile.objs          |   1 +
 hw/rtc/goldfish_rtc.c         | 288 ++++++++++++++++++++++++++++++++++
 hw/rtc/trace-events           |   4 +
 include/hw/rtc/goldfish_rtc.h |  46 ++++++
 5 files changed, 342 insertions(+)
 create mode 100644 hw/rtc/goldfish_rtc.c
 create mode 100644 include/hw/rtc/goldfish_rtc.h

Comments

Philippe Mathieu-Daudé Nov. 5, 2019, 11:24 p.m. UTC | #1
Hi Anup,

On 11/3/19 8:55 AM, Anup Patel wrote:
> This patch adds model for Google Goldfish virtual platform RTC device.
> 
> We will be adding Goldfish RTC device to the QEMU RISC-V virt machine
> for providing real date-time to Guest Linux. The corresponding Linux
> driver for Goldfish RTC device is already available in upstream Linux.
> 
> For now, VM migration support is available but untested for Goldfish RTC
> device. It will be hardened in-future when we implement VM migration for
> KVM RISC-V.
> 
> Signed-off-by: Anup Patel <anup.patel@wdc.com>
> Reviewed-by: Alistair Francis <alistair.francis@wdc.com>
> ---
>   hw/rtc/Kconfig                |   3 +
>   hw/rtc/Makefile.objs          |   1 +
>   hw/rtc/goldfish_rtc.c         | 288 ++++++++++++++++++++++++++++++++++
>   hw/rtc/trace-events           |   4 +
>   include/hw/rtc/goldfish_rtc.h |  46 ++++++

Correct path, thanks :)

>   5 files changed, 342 insertions(+)
>   create mode 100644 hw/rtc/goldfish_rtc.c
>   create mode 100644 include/hw/rtc/goldfish_rtc.h
> 
> diff --git a/hw/rtc/Kconfig b/hw/rtc/Kconfig
> index 45daa8d655..bafe6ac2c9 100644
> --- a/hw/rtc/Kconfig
> +++ b/hw/rtc/Kconfig
> @@ -21,3 +21,6 @@ config MC146818RTC
>   
>   config SUN4V_RTC
>       bool
> +
> +config GOLDFISH_RTC
> +    bool
> diff --git a/hw/rtc/Makefile.objs b/hw/rtc/Makefile.objs
> index 8dc9fcd3a9..aa208d0d10 100644
> --- a/hw/rtc/Makefile.objs
> +++ b/hw/rtc/Makefile.objs
> @@ -11,3 +11,4 @@ common-obj-$(CONFIG_EXYNOS4) += exynos4210_rtc.o
>   obj-$(CONFIG_MC146818RTC) += mc146818rtc.o
>   common-obj-$(CONFIG_SUN4V_RTC) += sun4v-rtc.o
>   common-obj-$(CONFIG_ASPEED_SOC) += aspeed_rtc.o
> +common-obj-$(CONFIG_GOLDFISH_RTC) += goldfish_rtc.o
> diff --git a/hw/rtc/goldfish_rtc.c b/hw/rtc/goldfish_rtc.c
> new file mode 100644
> index 0000000000..f71f6eaab0
> --- /dev/null
> +++ b/hw/rtc/goldfish_rtc.c
> @@ -0,0 +1,288 @@
> +/*
> + * Goldfish virtual platform RTC
> + *
> + * Copyright (C) 2019 Western Digital Corporation or its affiliates.
> + *
> + * For more details on Google Goldfish virtual platform refer:
> + * https://android.googlesource.com/platform/external/qemu/+/master/docs/GOLDFISH-VIRTUAL-HARDWARE.TXT

I'd use a (fixed) release tag, and not the (unstable) master branch:

https://android.googlesource.com/platform/external/qemu/+/refs/heads/emu-2.0-release/docs/GOLDFISH-VIRTUAL-HARDWARE.TXT

> + *
> + * This program is free software; you can redistribute it and/or modify it
> + * under the terms and conditions of the GNU General Public License,
> + * version 2 or later, as published by the Free Software Foundation.
> + *
> + * This program is distributed in the hope it will be useful, but WITHOUT
> + * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
> + * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
> + * more details.
> + *
> + * You should have received a copy of the GNU General Public License along with
> + * this program.  If not, see <http://www.gnu.org/licenses/>.
> + */
> +
> +#include "qemu/osdep.h"
> +#include "qemu-common.h"
> +#include "hw/rtc/goldfish_rtc.h"
> +#include "migration/vmstate.h"
> +#include "hw/irq.h"
> +#include "hw/qdev-properties.h"
> +#include "hw/sysbus.h"
> +#include "qemu/timer.h"
> +#include "sysemu/sysemu.h"
> +#include "qemu/cutils.h"
> +#include "qemu/log.h"
> +
> +#include "trace.h"
> +
> +#define RTC_TIME_LOW            0x00
> +#define RTC_TIME_HIGH           0x04
> +#define RTC_ALARM_LOW           0x08
> +#define RTC_ALARM_HIGH          0x0c
> +#define RTC_IRQ_ENABLED         0x10
> +#define RTC_CLEAR_ALARM         0x14
> +#define RTC_ALARM_STATUS        0x18
> +#define RTC_CLEAR_INTERRUPT     0x1c
> +
> +static void goldfish_rtc_update(GoldfishRTCState *s)
> +{
> +    qemu_set_irq(s->irq, (s->irq_pending & s->irq_enabled) ? 1 : 0);
> +}
> +
> +static void goldfish_rtc_interrupt(void *opaque)
> +{
> +    GoldfishRTCState *s = (GoldfishRTCState *)opaque;
> +
> +    s->alarm_running = 0;
> +    s->irq_pending = 1;
> +    goldfish_rtc_update(s);
> +}
> +
> +static uint64_t goldfish_rtc_get_count(GoldfishRTCState *s)
> +{
> +    return s->tick_offset + (uint64_t)qemu_clock_get_ns(rtc_clock);
> +}
> +
> +static void goldfish_rtc_clear_alarm(GoldfishRTCState *s)
> +{
> +    timer_del(s->timer);
> +    s->alarm_running = 0;
> +}
> +
> +static void goldfish_rtc_set_alarm(GoldfishRTCState *s)
> +{
> +    uint64_t ticks = goldfish_rtc_get_count(s);
> +    uint64_t event = s->alarm_next;
> +
> +    if (event <= ticks) {
> +        goldfish_rtc_clear_alarm(s);
> +        goldfish_rtc_interrupt(s);
> +    } else {
> +        /*
> +         * We should be setting timer expiry to:
> +         *     qemu_clock_get_ns(rtc_clock) + (event - ticks)
> +         * but this is equivalent to:
> +         *     event - s->tick_offset
> +         */
> +        timer_mod(s->timer, event - s->tick_offset);
> +        s->alarm_running = 1;
> +    }
> +}
> +
> +static uint64_t goldfish_rtc_read(void *opaque, hwaddr offset,
> +                                  unsigned size)
> +{
> +    GoldfishRTCState *s = opaque;
> +    uint64_t r = 0;
> +
> +    switch (offset) {
> +    case RTC_TIME_LOW:
> +        r = goldfish_rtc_get_count(s) & 0xffffffff;
> +        break;
> +    case RTC_TIME_HIGH:
> +        r = goldfish_rtc_get_count(s) >> 32;
> +        break;
> +    case RTC_ALARM_LOW:
> +        r = s->alarm_next & 0xffffffff;
> +        break;
> +    case RTC_ALARM_HIGH:
> +        r = s->alarm_next >> 32;
> +        break;
> +    case RTC_IRQ_ENABLED:
> +        r = s->irq_enabled;
> +        break;
> +    case RTC_ALARM_STATUS:
> +        r = s->alarm_running;
> +        break;
> +    default:
> +        qemu_log_mask(LOG_GUEST_ERROR,
> +                      "%s: Bad offset 0x%x\n", __func__, (uint32_t)offset);

Hmm 0x20 is UNIMP.

> +        break;
> +    }
> +
> +    trace_goldfish_rtc_read(offset, r);
> +
> +    return r;
> +}
> +
> +static void goldfish_rtc_write(void *opaque, hwaddr offset,
> +                               uint64_t value, unsigned size)
> +{
> +    GoldfishRTCState *s = opaque;
> +    uint64_t current_tick, new_tick;
> +
> +    switch (offset) {
> +    case RTC_TIME_LOW:
> +        current_tick = goldfish_rtc_get_count(s);

FYI, this 2 lines ...:

> +        new_tick = current_tick & (0xffffffffULL << 32);
> +        new_tick |= value;

... can also be written as:

            new_tick = deposit64(current_tick, 0, 32, value);

(I find this notation easier to review).

> +        s->tick_offset += new_tick - current_tick;
> +        break;
> +    case RTC_TIME_HIGH:
> +        current_tick = goldfish_rtc_get_count(s);
> +        new_tick = current_tick & 0xffffffffULL;
> +        new_tick |= (value << 32);
> +        s->tick_offset += new_tick - current_tick;
> +        break;
> +    case RTC_ALARM_LOW:
> +        s->alarm_next &= (0xffffffffULL << 32);
> +        s->alarm_next |= value;
> +        goldfish_rtc_set_alarm(s);
> +        break;
> +    case RTC_ALARM_HIGH:

Ditto these ...

> +        s->alarm_next &= 0xffffffffULL;
> +        s->alarm_next |= (value << 32);

... as:

            s->alarm_next = deposit64(s->alarm_next, 32, 32, value);

> +        break;
> +    case RTC_IRQ_ENABLED:
> +        s->irq_enabled = (uint32_t)(value & 0x1);
> +        goldfish_rtc_update(s);
> +        break;
> +    case RTC_CLEAR_ALARM:
> +        goldfish_rtc_clear_alarm(s);
> +        break;
> +    case RTC_CLEAR_INTERRUPT:
> +        s->irq_pending = 0;
> +        goldfish_rtc_update(s);
> +        break;
> +    default:
> +        qemu_log_mask(LOG_GUEST_ERROR,
> +                      "%s: Bad offset 0x%x\n", __func__, (uint32_t)offset);

0x20 is UNIMP.

> +        break;
> +    }
> +
> +    trace_goldfish_rtc_write(offset, value);
> +}
> +
> +static int goldfish_rtc_pre_save(void *opaque)
> +{
> +    uint64_t delta;
> +    GoldfishRTCState *s = opaque;
> +
> +    /*
> +     * We want to migrate this offset, which sounds straightforward.
> +     * Unfortunately, we cannot directly pass tick_offset because
> +     * rtc_clock on destination Host might not be same source Host.
> +     *
> +     * To tackle, this we pass tick_offset relative to vm_clock from
> +     * source Host and make it relative to rtc_clock at destination Host.

Hmm this is the fix from commit 032cfe6a79c.

> +     */
> +    delta = qemu_clock_get_ns(rtc_clock) -
> +            qemu_clock_get_ns(QEMU_CLOCK_VIRTUAL);
> +    s->tick_offset_vmstate = s->tick_offset + delta;
> +
> +    return 0;
> +}
> +
> +static int goldfish_rtc_post_load(void *opaque, int version_id)
> +{
> +    uint64_t delta;
> +    GoldfishRTCState *s = opaque;
> +
> +    /*
> +     * We extract tick_offset from tick_offset_vmstate by doing
> +     * reverse math compared to pre_save() function.
> +     */
> +    delta = qemu_clock_get_ns(rtc_clock) -
> +            qemu_clock_get_ns(QEMU_CLOCK_VIRTUAL);
> +    s->tick_offset = s->tick_offset_vmstate - delta;
> +
> +    return 0;
> +}
> +
> +static const MemoryRegionOps goldfish_rtc_ops = {
> +    .read = goldfish_rtc_read,
> +    .write = goldfish_rtc_write,
> +    .endianness = DEVICE_LITTLE_ENDIAN,
> +    .valid = {
> +        .min_access_size = 4,
> +        .max_access_size = 4

OK.

> +    }
> +};
> +
> +static const VMStateDescription goldfish_rtc_vmstate = {
> +    .name = TYPE_GOLDFISH_RTC,
> +    .version_id = 1,
> +    .pre_save = goldfish_rtc_pre_save,
> +    .post_load = goldfish_rtc_post_load,
> +    .fields = (VMStateField[]) {
> +        VMSTATE_UINT64(tick_offset_vmstate, GoldfishRTCState),
> +        VMSTATE_UINT64(alarm_next, GoldfishRTCState),
> +        VMSTATE_UINT32(alarm_running, GoldfishRTCState),
> +        VMSTATE_UINT32(irq_pending, GoldfishRTCState),
> +        VMSTATE_UINT32(irq_enabled, GoldfishRTCState),
> +        VMSTATE_END_OF_LIST()
> +    }
> +};
> +
> +static void goldfish_rtc_reset(DeviceState *dev)
> +{
> +    GoldfishRTCState *s = GOLDFISH_RTC(dev);
> +    struct tm tm;
> +
> +    timer_del(s->timer);
> +
> +    qemu_get_timedate(&tm, 0);
> +    s->tick_offset = mktimegm(&tm);
> +    s->tick_offset *= NANOSECONDS_PER_SECOND;
> +    s->tick_offset -= qemu_clock_get_ns(rtc_clock);
> +    s->tick_offset_vmstate = 0;
> +    s->alarm_next = 0;
> +    s->alarm_running = 0;
> +    s->irq_pending = 0;
> +    s->irq_enabled = 0;
> +}
> +
> +static void goldfish_rtc_realize(DeviceState *d, Error **errp)
> +{
> +    SysBusDevice *dev = SYS_BUS_DEVICE(d);
> +    GoldfishRTCState *s = GOLDFISH_RTC(d);
> +
> +    memory_region_init_io(&s->iomem, OBJECT(s), &goldfish_rtc_ops, s,
> +                          "goldfish_rtc", 0x1000);

The spec says this device's io region is 0x24 bytes. 0x1000 might be 
your SoC mapping. Restricting it to the spec allow other targets to use 
this device.

> +    sysbus_init_mmio(dev, &s->iomem);
> +
> +    sysbus_init_irq(dev, &s->irq);
> +
> +    s->timer = timer_new_ns(rtc_clock, goldfish_rtc_interrupt, s);
> +}
> +
> +static void goldfish_rtc_class_init(ObjectClass *klass, void *data)
> +{
> +    DeviceClass *dc = DEVICE_CLASS(klass);
> +
> +    dc->realize = goldfish_rtc_realize;
> +    dc->reset = goldfish_rtc_reset;
> +    dc->vmsd = &goldfish_rtc_vmstate;
> +}
> +
> +static const TypeInfo goldfish_rtc_info = {
> +    .name          = TYPE_GOLDFISH_RTC,
> +    .parent        = TYPE_SYS_BUS_DEVICE,
> +    .instance_size = sizeof(GoldfishRTCState),
> +    .class_init    = goldfish_rtc_class_init,
> +};
> +
> +static void goldfish_rtc_register_types(void)
> +{
> +    type_register_static(&goldfish_rtc_info);
> +}
> +
> +type_init(goldfish_rtc_register_types)
> diff --git a/hw/rtc/trace-events b/hw/rtc/trace-events
> index d6749f4616..0bfaa26cb8 100644
> --- a/hw/rtc/trace-events
> +++ b/hw/rtc/trace-events
> @@ -17,3 +17,7 @@ pl031_set_alarm(uint32_t ticks) "alarm set for %u ticks"
>   # aspeed-rtc.c
>   aspeed_rtc_read(uint64_t addr, uint64_t value) "addr 0x%02" PRIx64 " value 0x%08" PRIx64
>   aspeed_rtc_write(uint64_t addr, uint64_t value) "addr 0x%02" PRIx64 " value 0x%08" PRIx64
> +
> +# goldfish_rtc.c
> +goldfish_rtc_read(uint64_t addr, uint64_t value) "addr 0x%02" PRIx64 " value 0x%08" PRIx64
> +goldfish_rtc_write(uint64_t addr, uint64_t value) "addr 0x%02" PRIx64 " value 0x%08" PRIx64

You declared a region of 0x1000 bytes, shouldn't the address format be 
0x%03? I'd rather use the correct region size and keep 0x02 which is enough.

> diff --git a/include/hw/rtc/goldfish_rtc.h b/include/hw/rtc/goldfish_rtc.h
> new file mode 100644
> index 0000000000..3be586bdcb
> --- /dev/null
> +++ b/include/hw/rtc/goldfish_rtc.h
> @@ -0,0 +1,46 @@
> +/*
> + * Goldfish virtual platform RTC
> + *
> + * Copyright (C) 2019 Western Digital Corporation or its affiliates.
> + *
> + * For more details on Google Goldfish virtual platform refer:
> + * https://android.googlesource.com/platform/external/qemu/+/master/docs/GOLDFISH-VIRTUAL-HARDWARE.TXT
> + *
> + * This program is free software; you can redistribute it and/or modify it
> + * under the terms and conditions of the GNU General Public License,
> + * version 2 or later, as published by the Free Software Foundation.
> + *
> + * This program is distributed in the hope it will be useful, but WITHOUT
> + * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
> + * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
> + * more details.
> + *
> + * You should have received a copy of the GNU General Public License along with
> + * this program.  If not, see <http://www.gnu.org/licenses/>.
> + */
> +
> +#ifndef HW_RTC_GOLDFISH_RTC_H
> +#define HW_RTC_GOLDFISH_RTC_H
> +
> +#include "hw/sysbus.h"
> +
> +#define TYPE_GOLDFISH_RTC "goldfish_rtc"
> +#define GOLDFISH_RTC(obj) \
> +OBJECT_CHECK(GoldfishRTCState, (obj), TYPE_GOLDFISH_RTC)

Maybe insert some spaces before the macro to improve readability.

> +
> +typedef struct GoldfishRTCState {
> +    SysBusDevice parent_obj;
> +
> +    MemoryRegion iomem;
> +    QEMUTimer *timer;
> +    qemu_irq irq;
> +
> +    uint64_t tick_offset;
> +    uint64_t tick_offset_vmstate;
> +    uint64_t alarm_next;
> +    uint32_t alarm_running;
> +    uint32_t irq_pending;
> +    uint32_t irq_enabled;
> +} GoldfishRTCState;
> +
> +#endif
> 

Rest of the patch looks good.

Regards,

Phil.
Anup Patel Nov. 6, 2019, 6:39 a.m. UTC | #2
On Wed, Nov 6, 2019 at 4:54 AM Philippe Mathieu-Daudé <philmd@redhat.com> wrote:
>
> Hi Anup,
>
> On 11/3/19 8:55 AM, Anup Patel wrote:
> > This patch adds model for Google Goldfish virtual platform RTC device.
> >
> > We will be adding Goldfish RTC device to the QEMU RISC-V virt machine
> > for providing real date-time to Guest Linux. The corresponding Linux
> > driver for Goldfish RTC device is already available in upstream Linux.
> >
> > For now, VM migration support is available but untested for Goldfish RTC
> > device. It will be hardened in-future when we implement VM migration for
> > KVM RISC-V.
> >
> > Signed-off-by: Anup Patel <anup.patel@wdc.com>
> > Reviewed-by: Alistair Francis <alistair.francis@wdc.com>
> > ---
> >   hw/rtc/Kconfig                |   3 +
> >   hw/rtc/Makefile.objs          |   1 +
> >   hw/rtc/goldfish_rtc.c         | 288 ++++++++++++++++++++++++++++++++++
> >   hw/rtc/trace-events           |   4 +
> >   include/hw/rtc/goldfish_rtc.h |  46 ++++++
>
> Correct path, thanks :)
>
> >   5 files changed, 342 insertions(+)
> >   create mode 100644 hw/rtc/goldfish_rtc.c
> >   create mode 100644 include/hw/rtc/goldfish_rtc.h
> >
> > diff --git a/hw/rtc/Kconfig b/hw/rtc/Kconfig
> > index 45daa8d655..bafe6ac2c9 100644
> > --- a/hw/rtc/Kconfig
> > +++ b/hw/rtc/Kconfig
> > @@ -21,3 +21,6 @@ config MC146818RTC
> >
> >   config SUN4V_RTC
> >       bool
> > +
> > +config GOLDFISH_RTC
> > +    bool
> > diff --git a/hw/rtc/Makefile.objs b/hw/rtc/Makefile.objs
> > index 8dc9fcd3a9..aa208d0d10 100644
> > --- a/hw/rtc/Makefile.objs
> > +++ b/hw/rtc/Makefile.objs
> > @@ -11,3 +11,4 @@ common-obj-$(CONFIG_EXYNOS4) += exynos4210_rtc.o
> >   obj-$(CONFIG_MC146818RTC) += mc146818rtc.o
> >   common-obj-$(CONFIG_SUN4V_RTC) += sun4v-rtc.o
> >   common-obj-$(CONFIG_ASPEED_SOC) += aspeed_rtc.o
> > +common-obj-$(CONFIG_GOLDFISH_RTC) += goldfish_rtc.o
> > diff --git a/hw/rtc/goldfish_rtc.c b/hw/rtc/goldfish_rtc.c
> > new file mode 100644
> > index 0000000000..f71f6eaab0
> > --- /dev/null
> > +++ b/hw/rtc/goldfish_rtc.c
> > @@ -0,0 +1,288 @@
> > +/*
> > + * Goldfish virtual platform RTC
> > + *
> > + * Copyright (C) 2019 Western Digital Corporation or its affiliates.
> > + *
> > + * For more details on Google Goldfish virtual platform refer:
> > + * https://android.googlesource.com/platform/external/qemu/+/master/docs/GOLDFISH-VIRTUAL-HARDWARE.TXT
>
> I'd use a (fixed) release tag, and not the (unstable) master branch:
>
> https://android.googlesource.com/platform/external/qemu/+/refs/heads/emu-2.0-release/docs/GOLDFISH-VIRTUAL-HARDWARE.TXT

Sure, I will update the URL.

>
> > + *
> > + * This program is free software; you can redistribute it and/or modify it
> > + * under the terms and conditions of the GNU General Public License,
> > + * version 2 or later, as published by the Free Software Foundation.
> > + *
> > + * This program is distributed in the hope it will be useful, but WITHOUT
> > + * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
> > + * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
> > + * more details.
> > + *
> > + * You should have received a copy of the GNU General Public License along with
> > + * this program.  If not, see <http://www.gnu.org/licenses/>.
> > + */
> > +
> > +#include "qemu/osdep.h"
> > +#include "qemu-common.h"
> > +#include "hw/rtc/goldfish_rtc.h"
> > +#include "migration/vmstate.h"
> > +#include "hw/irq.h"
> > +#include "hw/qdev-properties.h"
> > +#include "hw/sysbus.h"
> > +#include "qemu/timer.h"
> > +#include "sysemu/sysemu.h"
> > +#include "qemu/cutils.h"
> > +#include "qemu/log.h"
> > +
> > +#include "trace.h"
> > +
> > +#define RTC_TIME_LOW            0x00
> > +#define RTC_TIME_HIGH           0x04
> > +#define RTC_ALARM_LOW           0x08
> > +#define RTC_ALARM_HIGH          0x0c
> > +#define RTC_IRQ_ENABLED         0x10
> > +#define RTC_CLEAR_ALARM         0x14
> > +#define RTC_ALARM_STATUS        0x18
> > +#define RTC_CLEAR_INTERRUPT     0x1c
> > +
> > +static void goldfish_rtc_update(GoldfishRTCState *s)
> > +{
> > +    qemu_set_irq(s->irq, (s->irq_pending & s->irq_enabled) ? 1 : 0);
> > +}
> > +
> > +static void goldfish_rtc_interrupt(void *opaque)
> > +{
> > +    GoldfishRTCState *s = (GoldfishRTCState *)opaque;
> > +
> > +    s->alarm_running = 0;
> > +    s->irq_pending = 1;
> > +    goldfish_rtc_update(s);
> > +}
> > +
> > +static uint64_t goldfish_rtc_get_count(GoldfishRTCState *s)
> > +{
> > +    return s->tick_offset + (uint64_t)qemu_clock_get_ns(rtc_clock);
> > +}
> > +
> > +static void goldfish_rtc_clear_alarm(GoldfishRTCState *s)
> > +{
> > +    timer_del(s->timer);
> > +    s->alarm_running = 0;
> > +}
> > +
> > +static void goldfish_rtc_set_alarm(GoldfishRTCState *s)
> > +{
> > +    uint64_t ticks = goldfish_rtc_get_count(s);
> > +    uint64_t event = s->alarm_next;
> > +
> > +    if (event <= ticks) {
> > +        goldfish_rtc_clear_alarm(s);
> > +        goldfish_rtc_interrupt(s);
> > +    } else {
> > +        /*
> > +         * We should be setting timer expiry to:
> > +         *     qemu_clock_get_ns(rtc_clock) + (event - ticks)
> > +         * but this is equivalent to:
> > +         *     event - s->tick_offset
> > +         */
> > +        timer_mod(s->timer, event - s->tick_offset);
> > +        s->alarm_running = 1;
> > +    }
> > +}
> > +
> > +static uint64_t goldfish_rtc_read(void *opaque, hwaddr offset,
> > +                                  unsigned size)
> > +{
> > +    GoldfishRTCState *s = opaque;
> > +    uint64_t r = 0;
> > +
> > +    switch (offset) {
> > +    case RTC_TIME_LOW:
> > +        r = goldfish_rtc_get_count(s) & 0xffffffff;
> > +        break;
> > +    case RTC_TIME_HIGH:
> > +        r = goldfish_rtc_get_count(s) >> 32;
> > +        break;
> > +    case RTC_ALARM_LOW:
> > +        r = s->alarm_next & 0xffffffff;
> > +        break;
> > +    case RTC_ALARM_HIGH:
> > +        r = s->alarm_next >> 32;
> > +        break;
> > +    case RTC_IRQ_ENABLED:
> > +        r = s->irq_enabled;
> > +        break;
> > +    case RTC_ALARM_STATUS:
> > +        r = s->alarm_running;
> > +        break;
> > +    default:
> > +        qemu_log_mask(LOG_GUEST_ERROR,
> > +                      "%s: Bad offset 0x%x\n", __func__, (uint32_t)offset);
>
> Hmm 0x20 is UNIMP.

Sure, I will update.

>
> > +        break;
> > +    }
> > +
> > +    trace_goldfish_rtc_read(offset, r);
> > +
> > +    return r;
> > +}
> > +
> > +static void goldfish_rtc_write(void *opaque, hwaddr offset,
> > +                               uint64_t value, unsigned size)
> > +{
> > +    GoldfishRTCState *s = opaque;
> > +    uint64_t current_tick, new_tick;
> > +
> > +    switch (offset) {
> > +    case RTC_TIME_LOW:
> > +        current_tick = goldfish_rtc_get_count(s);
>
> FYI, this 2 lines ...:
>
> > +        new_tick = current_tick & (0xffffffffULL << 32);
> > +        new_tick |= value;
>
> ... can also be written as:
>
>             new_tick = deposit64(current_tick, 0, 32, value);
>
> (I find this notation easier to review).

Sure, I will use deposite64() here and everywhere below.

Thanks for this suggestion.

>
> > +        s->tick_offset += new_tick - current_tick;
> > +        break;
> > +    case RTC_TIME_HIGH:
> > +        current_tick = goldfish_rtc_get_count(s);
> > +        new_tick = current_tick & 0xffffffffULL;
> > +        new_tick |= (value << 32);
> > +        s->tick_offset += new_tick - current_tick;
> > +        break;
> > +    case RTC_ALARM_LOW:
> > +        s->alarm_next &= (0xffffffffULL << 32);
> > +        s->alarm_next |= value;
> > +        goldfish_rtc_set_alarm(s);
> > +        break;
> > +    case RTC_ALARM_HIGH:
>
> Ditto these ...
>
> > +        s->alarm_next &= 0xffffffffULL;
> > +        s->alarm_next |= (value << 32);
>
> ... as:
>
>             s->alarm_next = deposit64(s->alarm_next, 32, 32, value);
>
> > +        break;
> > +    case RTC_IRQ_ENABLED:
> > +        s->irq_enabled = (uint32_t)(value & 0x1);
> > +        goldfish_rtc_update(s);
> > +        break;
> > +    case RTC_CLEAR_ALARM:
> > +        goldfish_rtc_clear_alarm(s);
> > +        break;
> > +    case RTC_CLEAR_INTERRUPT:
> > +        s->irq_pending = 0;
> > +        goldfish_rtc_update(s);
> > +        break;
> > +    default:
> > +        qemu_log_mask(LOG_GUEST_ERROR,
> > +                      "%s: Bad offset 0x%x\n", __func__, (uint32_t)offset);
>
> 0x20 is UNIMP.
>
> > +        break;
> > +    }
> > +
> > +    trace_goldfish_rtc_write(offset, value);
> > +}
> > +
> > +static int goldfish_rtc_pre_save(void *opaque)
> > +{
> > +    uint64_t delta;
> > +    GoldfishRTCState *s = opaque;
> > +
> > +    /*
> > +     * We want to migrate this offset, which sounds straightforward.
> > +     * Unfortunately, we cannot directly pass tick_offset because
> > +     * rtc_clock on destination Host might not be same source Host.
> > +     *
> > +     * To tackle, this we pass tick_offset relative to vm_clock from
> > +     * source Host and make it relative to rtc_clock at destination Host.
>
> Hmm this is the fix from commit 032cfe6a79c.
>
> > +     */
> > +    delta = qemu_clock_get_ns(rtc_clock) -
> > +            qemu_clock_get_ns(QEMU_CLOCK_VIRTUAL);
> > +    s->tick_offset_vmstate = s->tick_offset + delta;
> > +
> > +    return 0;
> > +}
> > +
> > +static int goldfish_rtc_post_load(void *opaque, int version_id)
> > +{
> > +    uint64_t delta;
> > +    GoldfishRTCState *s = opaque;
> > +
> > +    /*
> > +     * We extract tick_offset from tick_offset_vmstate by doing
> > +     * reverse math compared to pre_save() function.
> > +     */
> > +    delta = qemu_clock_get_ns(rtc_clock) -
> > +            qemu_clock_get_ns(QEMU_CLOCK_VIRTUAL);
> > +    s->tick_offset = s->tick_offset_vmstate - delta;
> > +
> > +    return 0;
> > +}
> > +
> > +static const MemoryRegionOps goldfish_rtc_ops = {
> > +    .read = goldfish_rtc_read,
> > +    .write = goldfish_rtc_write,
> > +    .endianness = DEVICE_LITTLE_ENDIAN,
> > +    .valid = {
> > +        .min_access_size = 4,
> > +        .max_access_size = 4
>
> OK.
>
> > +    }
> > +};
> > +
> > +static const VMStateDescription goldfish_rtc_vmstate = {
> > +    .name = TYPE_GOLDFISH_RTC,
> > +    .version_id = 1,
> > +    .pre_save = goldfish_rtc_pre_save,
> > +    .post_load = goldfish_rtc_post_load,
> > +    .fields = (VMStateField[]) {
> > +        VMSTATE_UINT64(tick_offset_vmstate, GoldfishRTCState),
> > +        VMSTATE_UINT64(alarm_next, GoldfishRTCState),
> > +        VMSTATE_UINT32(alarm_running, GoldfishRTCState),
> > +        VMSTATE_UINT32(irq_pending, GoldfishRTCState),
> > +        VMSTATE_UINT32(irq_enabled, GoldfishRTCState),
> > +        VMSTATE_END_OF_LIST()
> > +    }
> > +};
> > +
> > +static void goldfish_rtc_reset(DeviceState *dev)
> > +{
> > +    GoldfishRTCState *s = GOLDFISH_RTC(dev);
> > +    struct tm tm;
> > +
> > +    timer_del(s->timer);
> > +
> > +    qemu_get_timedate(&tm, 0);
> > +    s->tick_offset = mktimegm(&tm);
> > +    s->tick_offset *= NANOSECONDS_PER_SECOND;
> > +    s->tick_offset -= qemu_clock_get_ns(rtc_clock);
> > +    s->tick_offset_vmstate = 0;
> > +    s->alarm_next = 0;
> > +    s->alarm_running = 0;
> > +    s->irq_pending = 0;
> > +    s->irq_enabled = 0;
> > +}
> > +
> > +static void goldfish_rtc_realize(DeviceState *d, Error **errp)
> > +{
> > +    SysBusDevice *dev = SYS_BUS_DEVICE(d);
> > +    GoldfishRTCState *s = GOLDFISH_RTC(d);
> > +
> > +    memory_region_init_io(&s->iomem, OBJECT(s), &goldfish_rtc_ops, s,
> > +                          "goldfish_rtc", 0x1000);
>
> The spec says this device's io region is 0x24 bytes. 0x1000 might be
> your SoC mapping. Restricting it to the spec allow other targets to use
> this device.

Sure, I will update this.

>
> > +    sysbus_init_mmio(dev, &s->iomem);
> > +
> > +    sysbus_init_irq(dev, &s->irq);
> > +
> > +    s->timer = timer_new_ns(rtc_clock, goldfish_rtc_interrupt, s);
> > +}
> > +
> > +static void goldfish_rtc_class_init(ObjectClass *klass, void *data)
> > +{
> > +    DeviceClass *dc = DEVICE_CLASS(klass);
> > +
> > +    dc->realize = goldfish_rtc_realize;
> > +    dc->reset = goldfish_rtc_reset;
> > +    dc->vmsd = &goldfish_rtc_vmstate;
> > +}
> > +
> > +static const TypeInfo goldfish_rtc_info = {
> > +    .name          = TYPE_GOLDFISH_RTC,
> > +    .parent        = TYPE_SYS_BUS_DEVICE,
> > +    .instance_size = sizeof(GoldfishRTCState),
> > +    .class_init    = goldfish_rtc_class_init,
> > +};
> > +
> > +static void goldfish_rtc_register_types(void)
> > +{
> > +    type_register_static(&goldfish_rtc_info);
> > +}
> > +
> > +type_init(goldfish_rtc_register_types)
> > diff --git a/hw/rtc/trace-events b/hw/rtc/trace-events
> > index d6749f4616..0bfaa26cb8 100644
> > --- a/hw/rtc/trace-events
> > +++ b/hw/rtc/trace-events
> > @@ -17,3 +17,7 @@ pl031_set_alarm(uint32_t ticks) "alarm set for %u ticks"
> >   # aspeed-rtc.c
> >   aspeed_rtc_read(uint64_t addr, uint64_t value) "addr 0x%02" PRIx64 " value 0x%08" PRIx64
> >   aspeed_rtc_write(uint64_t addr, uint64_t value) "addr 0x%02" PRIx64 " value 0x%08" PRIx64
> > +
> > +# goldfish_rtc.c
> > +goldfish_rtc_read(uint64_t addr, uint64_t value) "addr 0x%02" PRIx64 " value 0x%08" PRIx64
> > +goldfish_rtc_write(uint64_t addr, uint64_t value) "addr 0x%02" PRIx64 " value 0x%08" PRIx64
>
> You declared a region of 0x1000 bytes, shouldn't the address format be
> 0x%03? I'd rather use the correct region size and keep 0x02 which is enough.

I will update the region size so we don't need to change here.

>
> > diff --git a/include/hw/rtc/goldfish_rtc.h b/include/hw/rtc/goldfish_rtc.h
> > new file mode 100644
> > index 0000000000..3be586bdcb
> > --- /dev/null
> > +++ b/include/hw/rtc/goldfish_rtc.h
> > @@ -0,0 +1,46 @@
> > +/*
> > + * Goldfish virtual platform RTC
> > + *
> > + * Copyright (C) 2019 Western Digital Corporation or its affiliates.
> > + *
> > + * For more details on Google Goldfish virtual platform refer:
> > + * https://android.googlesource.com/platform/external/qemu/+/master/docs/GOLDFISH-VIRTUAL-HARDWARE.TXT
> > + *
> > + * This program is free software; you can redistribute it and/or modify it
> > + * under the terms and conditions of the GNU General Public License,
> > + * version 2 or later, as published by the Free Software Foundation.
> > + *
> > + * This program is distributed in the hope it will be useful, but WITHOUT
> > + * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
> > + * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
> > + * more details.
> > + *
> > + * You should have received a copy of the GNU General Public License along with
> > + * this program.  If not, see <http://www.gnu.org/licenses/>.
> > + */
> > +
> > +#ifndef HW_RTC_GOLDFISH_RTC_H
> > +#define HW_RTC_GOLDFISH_RTC_H
> > +
> > +#include "hw/sysbus.h"
> > +
> > +#define TYPE_GOLDFISH_RTC "goldfish_rtc"
> > +#define GOLDFISH_RTC(obj) \
> > +OBJECT_CHECK(GoldfishRTCState, (obj), TYPE_GOLDFISH_RTC)
>
> Maybe insert some spaces before the macro to improve readability.

Okay.

>
> > +
> > +typedef struct GoldfishRTCState {
> > +    SysBusDevice parent_obj;
> > +
> > +    MemoryRegion iomem;
> > +    QEMUTimer *timer;
> > +    qemu_irq irq;
> > +
> > +    uint64_t tick_offset;
> > +    uint64_t tick_offset_vmstate;
> > +    uint64_t alarm_next;
> > +    uint32_t alarm_running;
> > +    uint32_t irq_pending;
> > +    uint32_t irq_enabled;
> > +} GoldfishRTCState;
> > +
> > +#endif
> >
>
> Rest of the patch looks good.

Thanks,
Anup
diff mbox series

Patch

diff --git a/hw/rtc/Kconfig b/hw/rtc/Kconfig
index 45daa8d655..bafe6ac2c9 100644
--- a/hw/rtc/Kconfig
+++ b/hw/rtc/Kconfig
@@ -21,3 +21,6 @@  config MC146818RTC
 
 config SUN4V_RTC
     bool
+
+config GOLDFISH_RTC
+    bool
diff --git a/hw/rtc/Makefile.objs b/hw/rtc/Makefile.objs
index 8dc9fcd3a9..aa208d0d10 100644
--- a/hw/rtc/Makefile.objs
+++ b/hw/rtc/Makefile.objs
@@ -11,3 +11,4 @@  common-obj-$(CONFIG_EXYNOS4) += exynos4210_rtc.o
 obj-$(CONFIG_MC146818RTC) += mc146818rtc.o
 common-obj-$(CONFIG_SUN4V_RTC) += sun4v-rtc.o
 common-obj-$(CONFIG_ASPEED_SOC) += aspeed_rtc.o
+common-obj-$(CONFIG_GOLDFISH_RTC) += goldfish_rtc.o
diff --git a/hw/rtc/goldfish_rtc.c b/hw/rtc/goldfish_rtc.c
new file mode 100644
index 0000000000..f71f6eaab0
--- /dev/null
+++ b/hw/rtc/goldfish_rtc.c
@@ -0,0 +1,288 @@ 
+/*
+ * Goldfish virtual platform RTC
+ *
+ * Copyright (C) 2019 Western Digital Corporation or its affiliates.
+ *
+ * For more details on Google Goldfish virtual platform refer:
+ * https://android.googlesource.com/platform/external/qemu/+/master/docs/GOLDFISH-VIRTUAL-HARDWARE.TXT
+ *
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms and conditions of the GNU General Public License,
+ * version 2 or later, as published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
+ * more details.
+ *
+ * You should have received a copy of the GNU General Public License along with
+ * this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+#include "qemu/osdep.h"
+#include "qemu-common.h"
+#include "hw/rtc/goldfish_rtc.h"
+#include "migration/vmstate.h"
+#include "hw/irq.h"
+#include "hw/qdev-properties.h"
+#include "hw/sysbus.h"
+#include "qemu/timer.h"
+#include "sysemu/sysemu.h"
+#include "qemu/cutils.h"
+#include "qemu/log.h"
+
+#include "trace.h"
+
+#define RTC_TIME_LOW            0x00
+#define RTC_TIME_HIGH           0x04
+#define RTC_ALARM_LOW           0x08
+#define RTC_ALARM_HIGH          0x0c
+#define RTC_IRQ_ENABLED         0x10
+#define RTC_CLEAR_ALARM         0x14
+#define RTC_ALARM_STATUS        0x18
+#define RTC_CLEAR_INTERRUPT     0x1c
+
+static void goldfish_rtc_update(GoldfishRTCState *s)
+{
+    qemu_set_irq(s->irq, (s->irq_pending & s->irq_enabled) ? 1 : 0);
+}
+
+static void goldfish_rtc_interrupt(void *opaque)
+{
+    GoldfishRTCState *s = (GoldfishRTCState *)opaque;
+
+    s->alarm_running = 0;
+    s->irq_pending = 1;
+    goldfish_rtc_update(s);
+}
+
+static uint64_t goldfish_rtc_get_count(GoldfishRTCState *s)
+{
+    return s->tick_offset + (uint64_t)qemu_clock_get_ns(rtc_clock);
+}
+
+static void goldfish_rtc_clear_alarm(GoldfishRTCState *s)
+{
+    timer_del(s->timer);
+    s->alarm_running = 0;
+}
+
+static void goldfish_rtc_set_alarm(GoldfishRTCState *s)
+{
+    uint64_t ticks = goldfish_rtc_get_count(s);
+    uint64_t event = s->alarm_next;
+
+    if (event <= ticks) {
+        goldfish_rtc_clear_alarm(s);
+        goldfish_rtc_interrupt(s);
+    } else {
+        /*
+         * We should be setting timer expiry to:
+         *     qemu_clock_get_ns(rtc_clock) + (event - ticks)
+         * but this is equivalent to:
+         *     event - s->tick_offset
+         */
+        timer_mod(s->timer, event - s->tick_offset);
+        s->alarm_running = 1;
+    }
+}
+
+static uint64_t goldfish_rtc_read(void *opaque, hwaddr offset,
+                                  unsigned size)
+{
+    GoldfishRTCState *s = opaque;
+    uint64_t r = 0;
+
+    switch (offset) {
+    case RTC_TIME_LOW:
+        r = goldfish_rtc_get_count(s) & 0xffffffff;
+        break;
+    case RTC_TIME_HIGH:
+        r = goldfish_rtc_get_count(s) >> 32;
+        break;
+    case RTC_ALARM_LOW:
+        r = s->alarm_next & 0xffffffff;
+        break;
+    case RTC_ALARM_HIGH:
+        r = s->alarm_next >> 32;
+        break;
+    case RTC_IRQ_ENABLED:
+        r = s->irq_enabled;
+        break;
+    case RTC_ALARM_STATUS:
+        r = s->alarm_running;
+        break;
+    default:
+        qemu_log_mask(LOG_GUEST_ERROR,
+                      "%s: Bad offset 0x%x\n", __func__, (uint32_t)offset);
+        break;
+    }
+
+    trace_goldfish_rtc_read(offset, r);
+
+    return r;
+}
+
+static void goldfish_rtc_write(void *opaque, hwaddr offset,
+                               uint64_t value, unsigned size)
+{
+    GoldfishRTCState *s = opaque;
+    uint64_t current_tick, new_tick;
+
+    switch (offset) {
+    case RTC_TIME_LOW:
+        current_tick = goldfish_rtc_get_count(s);
+        new_tick = current_tick & (0xffffffffULL << 32);
+        new_tick |= value;
+        s->tick_offset += new_tick - current_tick;
+        break;
+    case RTC_TIME_HIGH:
+        current_tick = goldfish_rtc_get_count(s);
+        new_tick = current_tick & 0xffffffffULL;
+        new_tick |= (value << 32);
+        s->tick_offset += new_tick - current_tick;
+        break;
+    case RTC_ALARM_LOW:
+        s->alarm_next &= (0xffffffffULL << 32);
+        s->alarm_next |= value;
+        goldfish_rtc_set_alarm(s);
+        break;
+    case RTC_ALARM_HIGH:
+        s->alarm_next &= 0xffffffffULL;
+        s->alarm_next |= (value << 32);
+        break;
+    case RTC_IRQ_ENABLED:
+        s->irq_enabled = (uint32_t)(value & 0x1);
+        goldfish_rtc_update(s);
+        break;
+    case RTC_CLEAR_ALARM:
+        goldfish_rtc_clear_alarm(s);
+        break;
+    case RTC_CLEAR_INTERRUPT:
+        s->irq_pending = 0;
+        goldfish_rtc_update(s);
+        break;
+    default:
+        qemu_log_mask(LOG_GUEST_ERROR,
+                      "%s: Bad offset 0x%x\n", __func__, (uint32_t)offset);
+        break;
+    }
+
+    trace_goldfish_rtc_write(offset, value);
+}
+
+static int goldfish_rtc_pre_save(void *opaque)
+{
+    uint64_t delta;
+    GoldfishRTCState *s = opaque;
+
+    /*
+     * We want to migrate this offset, which sounds straightforward.
+     * Unfortunately, we cannot directly pass tick_offset because
+     * rtc_clock on destination Host might not be same source Host.
+     *
+     * To tackle, this we pass tick_offset relative to vm_clock from
+     * source Host and make it relative to rtc_clock at destination Host.
+     */
+    delta = qemu_clock_get_ns(rtc_clock) -
+            qemu_clock_get_ns(QEMU_CLOCK_VIRTUAL);
+    s->tick_offset_vmstate = s->tick_offset + delta;
+
+    return 0;
+}
+
+static int goldfish_rtc_post_load(void *opaque, int version_id)
+{
+    uint64_t delta;
+    GoldfishRTCState *s = opaque;
+
+    /*
+     * We extract tick_offset from tick_offset_vmstate by doing
+     * reverse math compared to pre_save() function.
+     */
+    delta = qemu_clock_get_ns(rtc_clock) -
+            qemu_clock_get_ns(QEMU_CLOCK_VIRTUAL);
+    s->tick_offset = s->tick_offset_vmstate - delta;
+
+    return 0;
+}
+
+static const MemoryRegionOps goldfish_rtc_ops = {
+    .read = goldfish_rtc_read,
+    .write = goldfish_rtc_write,
+    .endianness = DEVICE_LITTLE_ENDIAN,
+    .valid = {
+        .min_access_size = 4,
+        .max_access_size = 4
+    }
+};
+
+static const VMStateDescription goldfish_rtc_vmstate = {
+    .name = TYPE_GOLDFISH_RTC,
+    .version_id = 1,
+    .pre_save = goldfish_rtc_pre_save,
+    .post_load = goldfish_rtc_post_load,
+    .fields = (VMStateField[]) {
+        VMSTATE_UINT64(tick_offset_vmstate, GoldfishRTCState),
+        VMSTATE_UINT64(alarm_next, GoldfishRTCState),
+        VMSTATE_UINT32(alarm_running, GoldfishRTCState),
+        VMSTATE_UINT32(irq_pending, GoldfishRTCState),
+        VMSTATE_UINT32(irq_enabled, GoldfishRTCState),
+        VMSTATE_END_OF_LIST()
+    }
+};
+
+static void goldfish_rtc_reset(DeviceState *dev)
+{
+    GoldfishRTCState *s = GOLDFISH_RTC(dev);
+    struct tm tm;
+
+    timer_del(s->timer);
+
+    qemu_get_timedate(&tm, 0);
+    s->tick_offset = mktimegm(&tm);
+    s->tick_offset *= NANOSECONDS_PER_SECOND;
+    s->tick_offset -= qemu_clock_get_ns(rtc_clock);
+    s->tick_offset_vmstate = 0;
+    s->alarm_next = 0;
+    s->alarm_running = 0;
+    s->irq_pending = 0;
+    s->irq_enabled = 0;
+}
+
+static void goldfish_rtc_realize(DeviceState *d, Error **errp)
+{
+    SysBusDevice *dev = SYS_BUS_DEVICE(d);
+    GoldfishRTCState *s = GOLDFISH_RTC(d);
+
+    memory_region_init_io(&s->iomem, OBJECT(s), &goldfish_rtc_ops, s,
+                          "goldfish_rtc", 0x1000);
+    sysbus_init_mmio(dev, &s->iomem);
+
+    sysbus_init_irq(dev, &s->irq);
+
+    s->timer = timer_new_ns(rtc_clock, goldfish_rtc_interrupt, s);
+}
+
+static void goldfish_rtc_class_init(ObjectClass *klass, void *data)
+{
+    DeviceClass *dc = DEVICE_CLASS(klass);
+
+    dc->realize = goldfish_rtc_realize;
+    dc->reset = goldfish_rtc_reset;
+    dc->vmsd = &goldfish_rtc_vmstate;
+}
+
+static const TypeInfo goldfish_rtc_info = {
+    .name          = TYPE_GOLDFISH_RTC,
+    .parent        = TYPE_SYS_BUS_DEVICE,
+    .instance_size = sizeof(GoldfishRTCState),
+    .class_init    = goldfish_rtc_class_init,
+};
+
+static void goldfish_rtc_register_types(void)
+{
+    type_register_static(&goldfish_rtc_info);
+}
+
+type_init(goldfish_rtc_register_types)
diff --git a/hw/rtc/trace-events b/hw/rtc/trace-events
index d6749f4616..0bfaa26cb8 100644
--- a/hw/rtc/trace-events
+++ b/hw/rtc/trace-events
@@ -17,3 +17,7 @@  pl031_set_alarm(uint32_t ticks) "alarm set for %u ticks"
 # aspeed-rtc.c
 aspeed_rtc_read(uint64_t addr, uint64_t value) "addr 0x%02" PRIx64 " value 0x%08" PRIx64
 aspeed_rtc_write(uint64_t addr, uint64_t value) "addr 0x%02" PRIx64 " value 0x%08" PRIx64
+
+# goldfish_rtc.c
+goldfish_rtc_read(uint64_t addr, uint64_t value) "addr 0x%02" PRIx64 " value 0x%08" PRIx64
+goldfish_rtc_write(uint64_t addr, uint64_t value) "addr 0x%02" PRIx64 " value 0x%08" PRIx64
diff --git a/include/hw/rtc/goldfish_rtc.h b/include/hw/rtc/goldfish_rtc.h
new file mode 100644
index 0000000000..3be586bdcb
--- /dev/null
+++ b/include/hw/rtc/goldfish_rtc.h
@@ -0,0 +1,46 @@ 
+/*
+ * Goldfish virtual platform RTC
+ *
+ * Copyright (C) 2019 Western Digital Corporation or its affiliates.
+ *
+ * For more details on Google Goldfish virtual platform refer:
+ * https://android.googlesource.com/platform/external/qemu/+/master/docs/GOLDFISH-VIRTUAL-HARDWARE.TXT
+ *
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms and conditions of the GNU General Public License,
+ * version 2 or later, as published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
+ * more details.
+ *
+ * You should have received a copy of the GNU General Public License along with
+ * this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+#ifndef HW_RTC_GOLDFISH_RTC_H
+#define HW_RTC_GOLDFISH_RTC_H
+
+#include "hw/sysbus.h"
+
+#define TYPE_GOLDFISH_RTC "goldfish_rtc"
+#define GOLDFISH_RTC(obj) \
+OBJECT_CHECK(GoldfishRTCState, (obj), TYPE_GOLDFISH_RTC)
+
+typedef struct GoldfishRTCState {
+    SysBusDevice parent_obj;
+
+    MemoryRegion iomem;
+    QEMUTimer *timer;
+    qemu_irq irq;
+
+    uint64_t tick_offset;
+    uint64_t tick_offset_vmstate;
+    uint64_t alarm_next;
+    uint32_t alarm_running;
+    uint32_t irq_pending;
+    uint32_t irq_enabled;
+} GoldfishRTCState;
+
+#endif