On Wed, Dec 3, 2014 at 8:18 AM, Marc Zyngier <marc.zyngier@xxxxxxx> wrote:
> There is a number of cases where a kernel subsystem may want to
> introspect the state of an interrupt at the irqchip level:
>
> - When a peripheral is shared between virtual machines,
> its interrupt state becomes part of the guest's state,
> and must be switched accordingly. KVM on arm/arm64 requires
> this for its guest-visible timer
> - Some GPIO controllers seem to require peeking into the
> interrupt controller they are connected to to report
> their internal state
>
> This seem to be a pattern that is common enough for the core code
> to try and support this without too many horrible hacks. Introduce
> a pair of accessors (irq_get_irqchip_state/irq_set_irqchip_state)
> to retrieve the bits that can be of interest to another subsystem:
> pending, active, and masked.
>
> - irq_get_irqchip_state returns the state of the interrupt according
> to a parameter set to IRQCHIP_STATE_PENDING, IRQCHIP_STATE_ACTIVE,
> IRQCHIP_STATE_MASKED or IRQCHIP_STATE_LINE_LEVEL.
> - irq_set_irqchip_state similarly sets the state of the interrupt.
>
> Signed-off-by: Marc Zyngier <marc.zyngier@xxxxxxx>
With the addition of actually assigning err to something useful in the
setter below:
Reviewed-by: Bjorn Andersson <bjorn.andersson@xxxxxxxxxxxxxx>
Tested-by: Bjorn Andersson <bjorn.andersson@xxxxxxxxxxxxxx>
> diff --git a/kernel/irq/manage.c b/kernel/irq/manage.c
[..]
> +/**
> + * irq_set_irqchip_state - set the state of a forwarded interrupt.
> + * @irq: Interrupt line that is forwarded to a VM
> + * @which: State to be restored (one of IRQCHIP_STATE_*)
> + * @val: Value corresponding to @which
> + *
> + * This call sets the internal irqchip state of an interrupt,
> + * depending on the value of @which.
> + *
> + * This function should be called with preemption disabled if the
> + * interrupt controller has per-cpu registers.
> + */
> +int irq_set_irqchip_state(unsigned int irq, enum irqchip_irq_state which,
> + bool val)
> +{
> + struct irq_desc *desc;
> + struct irq_data *data;
> + struct irq_chip *chip;
> + unsigned long flags;
> + int err = -EINVAL;
> +
> + desc = irq_get_desc_buslock(irq, &flags, 0);
> + if (!desc)
> + return err;
> +
> + data = irq_desc_get_irq_data(desc);
> +
> + do {
> + chip = irq_data_get_irq_chip(data);
> + if (chip->irq_set_irqchip_state)
> + break;
> +#ifdef CONFIG_IRQ_DOMAIN_HIERARCHY
> + data = data->parent_data;
> +#else
> + data = NULL;
> +#endif
> + } while (data);
> +
> + if (data)
> + chip->irq_set_irqchip_state(data, which, val);
err =
> +
> + irq_put_desc_busunlock(desc, flags);
> + return err;
> +}
Regards,
Bjorn
--
To unsubscribe from this list: send the line "unsubscribe linux-arm-msm" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
