Re: [PATCH v3 4/4] wdt_z069: Add support for MEN 16z069 Watchdog

[Alistair Francis]

On Tue, Apr 11, 2023 at 3:50 AM Johannes Thumshirn <jth@kernel.org> wrote:
>
> Add 16z069 Watchdog over MEN Chameleon BUS emulation.
>
> Signed-off-by: Johannes Thumshirn <jth@kernel.org>
> ---
>  hw/watchdog/Kconfig     |   5 +
>  hw/watchdog/meson.build |   1 +
>  hw/watchdog/wdt_z069.c  | 218 ++++++++++++++++++++++++++++++++++++++++
>  3 files changed, 224 insertions(+)
>  create mode 100644 hw/watchdog/wdt_z069.c
>
> diff --git a/hw/watchdog/Kconfig b/hw/watchdog/Kconfig
> index 66e1d029e3..a3f1196f66 100644
> --- a/hw/watchdog/Kconfig
> +++ b/hw/watchdog/Kconfig
> @@ -20,3 +20,8 @@ config WDT_IMX2
>
>  config WDT_SBSA
>      bool
> +
> +config WDT_Z069
> +    bool
> +    default y if MCB
> +    depends on MCB
> diff --git a/hw/watchdog/meson.build b/hw/watchdog/meson.build
> index 8974b5cf4c..7bc353774e 100644
> --- a/hw/watchdog/meson.build
> +++ b/hw/watchdog/meson.build
> @@ -6,4 +6,5 @@ softmmu_ss.add(when: 'CONFIG_WDT_DIAG288', if_true: 
> files('wdt_diag288.c'))
>  softmmu_ss.add(when: 'CONFIG_ASPEED_SOC', if_true: files('wdt_aspeed.c'))
>  softmmu_ss.add(when: 'CONFIG_WDT_IMX2', if_true: files('wdt_imx2.c'))
>  softmmu_ss.add(when: 'CONFIG_WDT_SBSA', if_true: files('sbsa_gwdt.c'))
> +softmmu_ss.add(when: 'CONFIG_WDT_Z069', if_true: files('wdt_z069.c'))
>  specific_ss.add(when: 'CONFIG_PSERIES', if_true: files('spapr_watchdog.c'))
> diff --git a/hw/watchdog/wdt_z069.c b/hw/watchdog/wdt_z069.c
> new file mode 100644
> index 0000000000..b20ceab532
> --- /dev/null
> +++ b/hw/watchdog/wdt_z069.c
> @@ -0,0 +1,218 @@
> +/*
> + * QEMU MEN 16z069 Watchdog over MCB emulation
> + *
> + * Copyright (C) 2023 Johannes Thumshirn <jth@kernel.org>
> + *
> + * This code is licensed under the GPL version 2 or later. See the
> + * COPYING file in the top-level directory.
> + */
> +#include "qemu/osdep.h"
> +#include "qemu/module.h"
> +#include "qemu/timer.h"
> +#include "sysemu/watchdog.h"
> +#include "hw/mcb/mcb.h"
> +#include "migration/vmstate.h"
> +#include "hw/qdev-properties.h"
> +
> +/* #define Z069_DEBUG 1 */
> +
> +#ifdef Z069_DEBUG
> +#define z069_debug(fmt, ...)                                        \
> +    fprintf(stderr, "wdt_z069: %s: "fmt, __func__, ##__VA_ARGS__)
> +#else
> +#define z069_debug(fmt, ...)
> +#endif

Same comment from the previous versions about using traces instead of
macro prints

Alistair

> +
> +#define MEN_Z069_WTR 0x10
> +#define MEN_Z069_WTR_WDEN BIT(15)
> +#define MEN_Z069_WTR_WDET_MASK  0x7fff
> +#define MEN_Z069_WVR 0x14
> +
> +#define CLK_500(x) ((x) * 2) /* 500Hz in ms */
> +
> +typedef struct {
> +    /*< private >*/
> +    MCBDevice dev;
> +
> +    /*< public >*/
> +    QEMUTimer *timer;
> +
> +    bool enabled;
> +    unsigned int timeout;
> +
> +    MemoryRegion mmio;
> +
> +    /* Registers */
> +    uint16_t wtr;
> +    uint16_t wvr;
> +} MENZ069State;
> +
> +static void men_z069_wdt_enable(MENZ069State *s)
> +{
> +    z069_debug("next timeout will fire in +%dms\n", s->timeout);
> +    timer_mod(s->timer, qemu_clock_get_ms(QEMU_CLOCK_VIRTUAL) + s->timeout);
> +}
> +
> +static void men_z069_wdt_disable(MENZ069State *s)
> +{
> +    timer_del(s->timer);
> +}
> +
> +static uint64_t men_z069_wdt_read(void *opaque, hwaddr addr, unsigned size)
> +{
> +    MENZ069State *s = opaque;
> +    uint64_t ret;
> +
> +    switch (addr) {
> +    case MEN_Z069_WTR:
> +        ret = s->wtr;
> +        break;
> +    case MEN_Z069_WVR:
> +        ret = s->wvr;
> +        break;
> +    default:
> +        ret = 0UL;
> +        break;
> +    }
> +
> +    z069_debug("returning: 0x%"PRIx64" @ 0x%lx\n", ret, addr);
> +    return ret;
> +}
> +
> +static void men_z069_wdt_write(void *opaque, hwaddr addr, uint64_t v,
> +                               unsigned size)
> +{
> +    MENZ069State *s = opaque;
> +    bool old_ena = s->enabled;
> +    uint16_t val = v & 0xffff;
> +    uint16_t tout;
> +
> +    z069_debug("got: 0x%"PRIx64" @ 0x%lx\n", v, addr);
> +
> +    switch (addr) {
> +    case MEN_Z069_WTR:
> +        s->wtr = val;
> +        tout = val & MEN_Z069_WTR_WDET_MASK;
> +        s->timeout = CLK_500(tout);
> +        s->enabled = val & MEN_Z069_WTR_WDEN;
> +        z069_debug("new timeout: %u (0x%x) %u\n", tout, tout, s->timeout);
> +
> +        if (old_ena && !s->enabled) {
> +            men_z069_wdt_disable(s);
> +        } else if (!old_ena && s->enabled) {
> +            men_z069_wdt_enable(s);
> +        }
> +
> +        break;
> +    case MEN_Z069_WVR:
> +        /* The watchdog trigger value toggles between 0x5555 and 0xaaaa */
> +        if (val == (s->wvr ^ 0xffff)) {
> +            s->wvr = val;
> +            z069_debug("watchdog triggered, next timeout will fire in 
> +%dms\n",
> +                       s->timeout);
> +            timer_mod(s->timer,
> +                      qemu_clock_get_ms(QEMU_CLOCK_VIRTUAL) + s->timeout);
> +        }
> +        break;
> +    default:
> +        break;
> +    }
> +    return;
> +}
> +
> +static const MemoryRegionOps men_z069_io_ops = {
> +    .read = men_z069_wdt_read,
> +    .write = men_z069_wdt_write,
> +    .endianness = DEVICE_LITTLE_ENDIAN,
> +    .valid = {
> +        .min_access_size = 4,
> +        .max_access_size = 4
> +    },
> +    .impl = {
> +        .min_access_size = 4,
> +        .max_access_size = 4
> +    },
> +};
> +
> +static void men_z069_timer_expired(void *opaque)
> +{
> +    MENZ069State *s = opaque;
> +
> +    watchdog_perform_action();
> +    timer_del(s->timer);
> +}
> +
> +static void men_z069_wdt_realize(DeviceState *dev, Error **errp)
> +{
> +    MCBDevice *mdev = MCB_DEVICE(dev);
> +    MENZ069State *s = DO_UPCAST(MENZ069State, dev, mdev);
> +    MCBus *bus = MCB_BUS(qdev_get_parent_bus(DEVICE(dev)));
> +
> +    mdev->gdd = mcb_new_chameleon_descriptor(bus, 69, mdev->rev,
> +                                             mdev->var, 0x18);
> +    if (!mdev->gdd) {
> +        return;
> +    }
> +
> +    s->wvr = 0x5555;
> +    s->wtr = 0x7fff;
> +    s->timeout = CLK_500(s->wtr & MEN_Z069_WTR_WDET_MASK);
> +    s->timer = timer_new_ms(QEMU_CLOCK_VIRTUAL,
> +                            men_z069_timer_expired, s);
> +
> +    memory_region_init_io(&s->mmio, OBJECT(s),
> +                          &men_z069_io_ops, s, "z069.wdt", 0x16);
> +    memory_region_add_subregion(&bus->mmio_region, mdev->gdd->offset,
> +                                &s->mmio);
> +}
> +
> +static void men_z069_wdt_unrealize(DeviceState *dev)
> +{
> +    MCBDevice *mdev = MCB_DEVICE(dev);
> +
> +    g_free(&mdev->gdd);
> +}
> +
> +static const VMStateDescription vmstate_z069_wdt = {
> +    .name = "z069-wdt",
> +    .version_id = 1,
> +    .minimum_version_id = 1,
> +    .fields = (VMStateField[]) {
> +        VMSTATE_MCB_DEVICE(dev, MENZ069State),
> +        VMSTATE_TIMER_PTR(timer, MENZ069State),
> +        VMSTATE_END_OF_LIST()
> +    }
> +};
> +
> +static Property men_z069_wdt_properties[] = {
> +    DEFINE_PROP_UINT8("rev", MENZ069State, dev.rev, 0),
> +    DEFINE_PROP_UINT8("var", MENZ069State, dev.var, 0),
> +    DEFINE_PROP_END_OF_LIST(),
> +};
> +
> +static void men_z069_wdt_class_intifn(ObjectClass *klass, void *data)
> +{
> +    DeviceClass *dc = DEVICE_CLASS(klass);
> +    MCBDeviceClass *mc = MCB_DEVICE_CLASS(klass);
> +
> +    mc->realize = men_z069_wdt_realize;
> +    mc->unrealize = men_z069_wdt_unrealize;
> +
> +    dc->desc = "MEN 16z069 Watchdog Timer";
> +    dc->vmsd = &vmstate_z069_wdt;
> +    device_class_set_props(dc, men_z069_wdt_properties);
> +}
> +
> +static const TypeInfo men_z069_wdt_info = {
> +    .name = "z069-wdt",
> +    .parent = TYPE_MCB_DEVICE,
> +    .instance_size = sizeof(MENZ069State),
> +    .class_init = men_z069_wdt_class_intifn,
> +};
> +
> +static void men_z069_wdt_register_types(void)
> +{
> +    type_register_static(&men_z069_wdt_info);
> +}
> +
> +type_init(men_z069_wdt_register_types);
> --
> 2.39.2
>
>