Re: [PATCH v2 5/5] hw/intc: ibex_timer: Convert the timer to use RISC-V CPU GPIO lines

[Bin Meng]

On Wed, Jul 14, 2021 at 3:25 PM Alistair Francis
<alistair.francis@wdc.com> wrote:
>
> Instead of using riscv_cpu_update_mip() let's instead use the new RISC-V
> CPU GPIO lines to set the timer MIP bits.
>
> Signed-off-by: Alistair Francis <alistair.francis@wdc.com>
> Reviewed-by: Philippe Mathieu-Daudé <f4bug@amsat.org>
> Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
> ---
>  include/hw/timer/ibex_timer.h |  2 ++
>  hw/riscv/opentitan.c          |  3 +++
>  hw/timer/ibex_timer.c         | 17 ++++++++++++-----
>  3 files changed, 17 insertions(+), 5 deletions(-)
>
> diff --git a/include/hw/timer/ibex_timer.h b/include/hw/timer/ibex_timer.h
> index 6a43537003..b6f69b38ee 100644
> --- a/include/hw/timer/ibex_timer.h
> +++ b/include/hw/timer/ibex_timer.h
> @@ -48,5 +48,7 @@ struct IbexTimerState {
>      uint32_t timebase_freq;
>
>      qemu_irq irq;
> +
> +    qemu_irq m_timer_irq;
>  };
>  #endif /* HW_IBEX_TIMER_H */
> diff --git a/hw/riscv/opentitan.c b/hw/riscv/opentitan.c
> index 88a0200972..fb0750c16f 100644
> --- a/hw/riscv/opentitan.c
> +++ b/hw/riscv/opentitan.c
> @@ -176,6 +176,9 @@ static void lowrisc_ibex_soc_realize(DeviceState 
> *dev_soc, Error **errp)
>      sysbus_connect_irq(SYS_BUS_DEVICE(&s->timer),
>                         0, qdev_get_gpio_in(DEVICE(&s->plic),
>                         IBEX_TIMER_TIMEREXPIRED0_0));
> +    qdev_connect_gpio_out_named(DEVICE(&s->timer), NULL, 0,

nits: use qdev_connect_gpio_out

> +                                qdev_get_gpio_in(DEVICE(qemu_get_cpu(0)),

Does this timer device only support one CPU?

> +                                                 IRQ_M_TIMER));
>
>      create_unimplemented_device("riscv.lowrisc.ibex.gpio",
>          memmap[IBEX_DEV_GPIO].base, memmap[IBEX_DEV_GPIO].size);
> diff --git a/hw/timer/ibex_timer.c b/hw/timer/ibex_timer.c
> index 5befb53506..66e1f8e48c 100644
> --- a/hw/timer/ibex_timer.c
> +++ b/hw/timer/ibex_timer.c
> @@ -77,7 +77,7 @@ static void ibex_timer_update_irqs(IbexTimerState *s)
>          /*
>           * If the mtimecmp was in the past raise the interrupt now.
>           */
> -        riscv_cpu_update_mip(cpu, MIP_MTIP, BOOL_TO_MASK(1));
> +        qemu_irq_raise(s->m_timer_irq);
>          if (s->timer_intr_enable & R_INTR_ENABLE_IE_0_MASK) {
>              s->timer_intr_state |= R_INTR_STATE_IS_0_MASK;
>              qemu_set_irq(s->irq, true);
> @@ -86,7 +86,7 @@ static void ibex_timer_update_irqs(IbexTimerState *s)
>      }
>
>      /* Setup a timer to trigger the interrupt in the future */
> -    riscv_cpu_update_mip(cpu, MIP_MTIP, BOOL_TO_MASK(0));
> +    qemu_irq_lower(s->m_timer_irq);
>      qemu_set_irq(s->irq, false);
>
>      diff = cpu->env.timecmp - now;
> @@ -106,10 +106,8 @@ static void ibex_timer_update_irqs(IbexTimerState *s)
>  static void ibex_timer_cb(void *opaque)
>  {
>      IbexTimerState *s = opaque;
> -    CPUState *cs = qemu_get_cpu(0);
> -    RISCVCPU *cpu = RISCV_CPU(cs);
>
> -    riscv_cpu_update_mip(cpu, MIP_MTIP, BOOL_TO_MASK(1));
> +    qemu_irq_raise(s->m_timer_irq);
>      if (s->timer_intr_enable & R_INTR_ENABLE_IE_0_MASK) {
>          s->timer_intr_state |= R_INTR_STATE_IS_0_MASK;
>          qemu_set_irq(s->irq, true);
> @@ -280,12 +278,21 @@ static void ibex_timer_init(Object *obj)
>      sysbus_init_mmio(SYS_BUS_DEVICE(obj), &s->mmio);
>  }
>
> +static void ibex_timer_realize(DeviceState *dev, Error **errp)
> +{
> +    IbexTimerState *s = IBEX_TIMER(dev);
> +
> +    qdev_init_gpio_out(dev, &s->m_timer_irq, 1);
> +}
> +
> +
>  static void ibex_timer_class_init(ObjectClass *klass, void *data)
>  {
>      DeviceClass *dc = DEVICE_CLASS(klass);
>
>      dc->reset = ibex_timer_reset;
>      dc->vmsd = &vmstate_ibex_timer;
> +    dc->realize = ibex_timer_realize;
>      device_class_set_props(dc, ibex_timer_properties);
>  }
>

Regards,
Bin