Add enough code to emulate i.MX2 watchdog IP block so it would be
possible to reboot the machine running Linux Guest.

Cc: Peter Maydell <peter.maydell@linaro.org>
Cc: Jason Wang <jasowang@redhat.com>
Cc: Philippe Mathieu-Daudé <f4bug@amsat.org>
Cc: qemu-devel@nongnu.org
Cc: qemu-arm@nongnu.org
Cc: yurovsky@gmail.com
Reviewed-by: Peter Maydell <peter.maydell@linaro.org>
Signed-off-by: Andrey Smirnov <andrew.smirnov@gmail.com>
---
 hw/misc/Makefile.objs      |  1 +
 hw/misc/imx2_wdt.c         | 89 ++++++++++++++++++++++++++++++++++++++++++++++
 include/hw/misc/imx2_wdt.h | 33 +++++++++++++++++
 3 files changed, 123 insertions(+)
 create mode 100644 hw/misc/imx2_wdt.c
 create mode 100644 include/hw/misc/imx2_wdt.h

diff --git a/hw/misc/Makefile.objs b/hw/misc/Makefile.objs
index a28e5e49b0..4b2b705a6c 100644
--- a/hw/misc/Makefile.objs
+++ b/hw/misc/Makefile.objs
@@ -34,6 +34,7 @@ obj-$(CONFIG_IMX) += imx25_ccm.o
 obj-$(CONFIG_IMX) += imx6_ccm.o
 obj-$(CONFIG_IMX) += imx6_src.o
 obj-$(CONFIG_IMX) += imx7_ccm.o
+obj-$(CONFIG_IMX) += imx2_wdt.o
 obj-$(CONFIG_MILKYMIST) += milkymist-hpdmc.o
 obj-$(CONFIG_MILKYMIST) += milkymist-pfpu.o
 obj-$(CONFIG_MAINSTONE) += mst_fpga.o
diff --git a/hw/misc/imx2_wdt.c b/hw/misc/imx2_wdt.c
new file mode 100644
index 0000000000..76bb98a525
--- /dev/null
+++ b/hw/misc/imx2_wdt.c
@@ -0,0 +1,89 @@
+/*
+ * Copyright (c) 2017, Impinj, Inc.
+ *
+ * i.MX2 Watchdog IP block
+ *
+ * Author: Andrey Smirnov <andrew.smirnov@gmail.com>
+ *
+ * This work is licensed under the terms of the GNU GPL, version 2 or later.
+ * See the COPYING file in the top-level directory.
+ */
+
+#include "qemu/bitops.h"
+#include "qemu/osdep.h"
+#include "sysemu/watchdog.h"
+
+#include "hw/misc/imx2_wdt.h"
+
+#define IMX2_WDT_WCR_WDA    BIT(5)      /* -> External Reset WDOG_B */
+#define IMX2_WDT_WCR_SRS    BIT(4)      /* -> Software Reset Signal */
+
+static uint64_t imx2_wdt_read(void *opaque, hwaddr addr,
+                              unsigned int size)
+{
+    return 0;
+}
+
+static void imx2_wdt_write(void *opaque, hwaddr addr,
+                           uint64_t value, unsigned int size)
+{
+    if (addr == IMX2_WDT_WCR &&
+        (value & (IMX2_WDT_WCR_WDA | IMX2_WDT_WCR_SRS))) {
+        watchdog_perform_action();
+    }
+}
+
+static const MemoryRegionOps imx2_wdt_ops = {
+    .read  = imx2_wdt_read,
+    .write = imx2_wdt_write,
+    .endianness = DEVICE_NATIVE_ENDIAN,
+    .impl = {
+        /*
+         * Our device would not work correctly if the guest was doing
+         * unaligned access. This might not be a limitation on the
+         * real device but in practice there is no reason for a guest
+         * to access this device unaligned.
+         */
+        .min_access_size = 4,
+        .max_access_size = 4,
+        .unaligned = false,
+    },
+};
+
+static void imx2_wdt_realize(DeviceState *dev, Error **errp)
+{
+    IMX2WdtState *s = IMX2_WDT(dev);
+
+    memory_region_init_io(&s->mmio, OBJECT(dev),
+                          &imx2_wdt_ops, s,
+                          TYPE_IMX2_WDT".mmio",
+                          IMX2_WDT_REG_NUM * sizeof(uint16_t));
+    sysbus_init_mmio(SYS_BUS_DEVICE(dev), &s->mmio);
+}
+
+static void imx2_wdt_class_init(ObjectClass *klass, void *data)
+{
+    DeviceClass *dc = DEVICE_CLASS(klass);
+
+    dc->realize = imx2_wdt_realize;
+    set_bit(DEVICE_CATEGORY_MISC, dc->categories);
+}
+
+static const TypeInfo imx2_wdt_info = {
+    .name          = TYPE_IMX2_WDT,
+    .parent        = TYPE_SYS_BUS_DEVICE,
+    .instance_size = sizeof(IMX2WdtState),
+    .class_init    = imx2_wdt_class_init,
+};
+
+static WatchdogTimerModel model = {
+    .wdt_name = "imx2-watchdog",
+    .wdt_description = "i.MX2 Watchdog",
+};
+
+static void imx2_wdt_register_type(void)
+{
+    watchdog_add_model(&model);
+    type_register_static(&imx2_wdt_info);
+}
+type_init(imx2_wdt_register_type)
diff --git a/include/hw/misc/imx2_wdt.h b/include/hw/misc/imx2_wdt.h
new file mode 100644
index 0000000000..8afc99a10e
--- /dev/null
+++ b/include/hw/misc/imx2_wdt.h
@@ -0,0 +1,33 @@
+/*
+ * Copyright (c) 2017, Impinj, Inc.
+ *
+ * i.MX2 Watchdog IP block
+ *
+ * Author: Andrey Smirnov <andrew.smirnov@gmail.com>
+ *
+ * This work is licensed under the terms of the GNU GPL, version 2 or later.
+ * See the COPYING file in the top-level directory.
+ */
+
+#ifndef IMX2_WDT_H
+#define IMX2_WDT_H
+
+#include "hw/sysbus.h"
+
+#define TYPE_IMX2_WDT "imx2.wdt"
+#define IMX2_WDT(obj) OBJECT_CHECK(IMX2WdtState, (obj), TYPE_IMX2_WDT)
+
+enum IMX2WdtRegisters {
+    IMX2_WDT_WCR     = 0x0000,
+    IMX2_WDT_REG_NUM = 0x0008 / sizeof(uint16_t) + 1,
+};
+
+
+typedef struct IMX2WdtState {
+    /* <private> */
+    SysBusDevice parent_obj;
+
+    MemoryRegion mmio;
+} IMX2WdtState;
+
+#endif /* IMX7_SNVS_H */
-- 
2.14.3

On 01/15/2018 10:36 PM, Andrey Smirnov wrote:
> Add enough code to emulate i.MX2 watchdog IP block so it would be
> possible to reboot the machine running Linux Guest.
> 
> Cc: Peter Maydell <peter.maydell@linaro.org>
> Cc: Jason Wang <jasowang@redhat.com>
> Cc: Philippe Mathieu-Daudé <f4bug@amsat.org>
> Cc: qemu-devel@nongnu.org
> Cc: qemu-arm@nongnu.org
> Cc: yurovsky@gmail.com
> Reviewed-by: Peter Maydell <peter.maydell@linaro.org>
> Signed-off-by: Andrey Smirnov <andrew.smirnov@gmail.com>
> ---
>  hw/misc/Makefile.objs      |  1 +
>  hw/misc/imx2_wdt.c         | 89 ++++++++++++++++++++++++++++++++++++++++++++++
>  include/hw/misc/imx2_wdt.h | 33 +++++++++++++++++
>  3 files changed, 123 insertions(+)
>  create mode 100644 hw/misc/imx2_wdt.c
>  create mode 100644 include/hw/misc/imx2_wdt.h
> 
> diff --git a/hw/misc/Makefile.objs b/hw/misc/Makefile.objs
> index a28e5e49b0..4b2b705a6c 100644
> --- a/hw/misc/Makefile.objs
> +++ b/hw/misc/Makefile.objs
> @@ -34,6 +34,7 @@ obj-$(CONFIG_IMX) += imx25_ccm.o
>  obj-$(CONFIG_IMX) += imx6_ccm.o
>  obj-$(CONFIG_IMX) += imx6_src.o
>  obj-$(CONFIG_IMX) += imx7_ccm.o
> +obj-$(CONFIG_IMX) += imx2_wdt.o
>  obj-$(CONFIG_MILKYMIST) += milkymist-hpdmc.o
>  obj-$(CONFIG_MILKYMIST) += milkymist-pfpu.o
>  obj-$(CONFIG_MAINSTONE) += mst_fpga.o
> diff --git a/hw/misc/imx2_wdt.c b/hw/misc/imx2_wdt.c
> new file mode 100644
> index 0000000000..76bb98a525
> --- /dev/null
> +++ b/hw/misc/imx2_wdt.c
> @@ -0,0 +1,89 @@
> +/*
> + * Copyright (c) 2017, Impinj, Inc.
> + *
> + * i.MX2 Watchdog IP block
> + *
> + * Author: Andrey Smirnov <andrew.smirnov@gmail.com>
> + *
> + * This work is licensed under the terms of the GNU GPL, version 2 or later.
> + * See the COPYING file in the top-level directory.
> + */
> +
> +#include "qemu/bitops.h"
> +#include "qemu/osdep.h"
> +#include "sysemu/watchdog.h"
> +
> +#include "hw/misc/imx2_wdt.h"
> +
> +#define IMX2_WDT_WCR_WDA    BIT(5)      /* -> External Reset WDOG_B */
> +#define IMX2_WDT_WCR_SRS    BIT(4)      /* -> Software Reset Signal */
> +
> +static uint64_t imx2_wdt_read(void *opaque, hwaddr addr,
> +                              unsigned int size)
> +{
> +    return 0;
> +}
> +
> +static void imx2_wdt_write(void *opaque, hwaddr addr,
> +                           uint64_t value, unsigned int size)
> +{
> +    if (addr == IMX2_WDT_WCR &&
> +        (value & (IMX2_WDT_WCR_WDA | IMX2_WDT_WCR_SRS))) {
> +        watchdog_perform_action();
> +    }
> +}
> +
> +static const MemoryRegionOps imx2_wdt_ops = {
> +    .read  = imx2_wdt_read,

Maybe you can just drop the .read entry and imx2_wdt_read().

> +    .write = imx2_wdt_write,
> +    .endianness = DEVICE_NATIVE_ENDIAN,
> +    .impl = {
> +        /*
> +         * Our device would not work correctly if the guest was doing
> +         * unaligned access. This might not be a limitation on the
> +         * real device but in practice there is no reason for a guest
> +         * to access this device unaligned.
> +         */
> +        .min_access_size = 4,
> +        .max_access_size = 4,
> +        .unaligned = false,
> +    },
> +};
> +
> +static void imx2_wdt_realize(DeviceState *dev, Error **errp)
> +{
> +    IMX2WdtState *s = IMX2_WDT(dev);
> +
> +    memory_region_init_io(&s->mmio, OBJECT(dev),
> +                          &imx2_wdt_ops, s,
> +                          TYPE_IMX2_WDT".mmio",
> +                          IMX2_WDT_REG_NUM * sizeof(uint16_t));
> +    sysbus_init_mmio(SYS_BUS_DEVICE(dev), &s->mmio);
> +}
> +
> +static void imx2_wdt_class_init(ObjectClass *klass, void *data)
> +{
> +    DeviceClass *dc = DEVICE_CLASS(klass);
> +
> +    dc->realize = imx2_wdt_realize;
> +    set_bit(DEVICE_CATEGORY_MISC, dc->categories);
> +}
> +
> +static const TypeInfo imx2_wdt_info = {
> +    .name          = TYPE_IMX2_WDT,
> +    .parent        = TYPE_SYS_BUS_DEVICE,
> +    .instance_size = sizeof(IMX2WdtState),
> +    .class_init    = imx2_wdt_class_init,
> +};
> +
> +static WatchdogTimerModel model = {
> +    .wdt_name = "imx2-watchdog",
> +    .wdt_description = "i.MX2 Watchdog",
> +};
> +
> +static void imx2_wdt_register_type(void)
> +{
> +    watchdog_add_model(&model);
> +    type_register_static(&imx2_wdt_info);
> +}
> +type_init(imx2_wdt_register_type)
> diff --git a/include/hw/misc/imx2_wdt.h b/include/hw/misc/imx2_wdt.h
> new file mode 100644
> index 0000000000..8afc99a10e
> --- /dev/null
> +++ b/include/hw/misc/imx2_wdt.h
> @@ -0,0 +1,33 @@
> +/*
> + * Copyright (c) 2017, Impinj, Inc.
> + *
> + * i.MX2 Watchdog IP block
> + *
> + * Author: Andrey Smirnov <andrew.smirnov@gmail.com>
> + *
> + * This work is licensed under the terms of the GNU GPL, version 2 or later.
> + * See the COPYING file in the top-level directory.
> + */
> +
> +#ifndef IMX2_WDT_H
> +#define IMX2_WDT_H
> +
> +#include "hw/sysbus.h"
> +
> +#define TYPE_IMX2_WDT "imx2.wdt"
> +#define IMX2_WDT(obj) OBJECT_CHECK(IMX2WdtState, (obj), TYPE_IMX2_WDT)
> +
> +enum IMX2WdtRegisters {
> +    IMX2_WDT_WCR     = 0x0000,
> +    IMX2_WDT_REG_NUM = 0x0008 / sizeof(uint16_t) + 1,
> +};
> +
> +
> +typedef struct IMX2WdtState {
> +    /* <private> */
> +    SysBusDevice parent_obj;
> +
> +    MemoryRegion mmio;
> +} IMX2WdtState;
> +
> +#endif /* IMX7_SNVS_H */
>