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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