powerpc/powernv: Support OPAL requested heartbeat

[Michael Ellerman]

On Wed, 2014-12-11 at 06:03:14 UTC, Benjamin Herrenschmidt wrote:
> If OPAL requests it, call it back via opal_poll_events() at a
> regular interval. Some versions of OPAL on some machines require
> this to operate some internal timeouts properly.
> 
> diff --git a/arch/powerpc/platforms/powernv/opal.c b/arch/powerpc/platforms/powernv/opal.c
> index f1e0d8c..0153064 100644
> --- a/arch/powerpc/platforms/powernv/opal.c
> +++ b/arch/powerpc/platforms/powernv/opal.c
> @@ -678,6 +680,49 @@ static int __init opal_init(void)
>  				   " (0x%x)\n", rc, irq, hwirq);
>  		opal_irqs[i] = irq;
>  	}
> +}
> +
> +static int kopald(void *unused)
> +{
> +	set_freezable();
> +	do {
> +		try_to_freeze();
> +		opal_poll_events(NULL);
> +		msleep_interruptible(opal_heartbeat);
> +	} while (!kthread_should_stop());
> +
> +	return 0;
> +}
> +
> +static void opal_init_heartbeat(void)
> +{
> +	/* Old firwmware, we assume the HVC heartbeat is sufficient */
> +	if (of_property_read_u32(opal_node, "ibm,heartbeat-freq",
> +				 &opal_heartbeat) != 0)

I'd assume "freq" with no units is in HZ, but looks like it's milliseconds. I
guess it's too late to rename it.

cheers