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SubjectRe: [RFC PATCH] genirq: implement read_irq_line for interrupt lines
On 04/15/2011 11:42 AM, Abhijeet Dharmapurikar wrote:
[...]
>
> +/**
> + * irq_read_line - read the value on an irq line
> + * @irq: Interrupt number representing a hardware line
> + *
> + * This function may be called from IRQ context only when
> + * desc->chip->bus_lock and desc->chip->bus_sync_unlock are NULL !

What does it return? I can see that -EINVAL is returned if it isn't
applicable to this irq. But what if chip->irq_read_line is implemented?




> + */
> +int irq_read_line(unsigned int irq)
> +{
> + struct irq_desc *desc = irq_to_desc(irq);
> + unsigned long flags;
> + int val;
> +
> + if (!desc || !desc->irq_data.chip->irq_read_line)
> + return -EINVAL;
> +
> + chip_bus_lock(desc);
> + raw_spin_lock_irqsave(&desc->lock, flags);
> + val = desc->irq_data.chip->irq_read_line(&desc->irq_data);
> + raw_spin_unlock_irqrestore(&desc->lock, flags);
> + chip_bus_sync_unlock(desc);
> + return val;
> +}
> +EXPORT_SYMBOL(irq_read_line);
> +
> /*
> * Internal function that tells the architecture code whether a
> * particular irq has been exclusively allocated or is available



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