+/**
+ * handle_uic_irq - irq flow handler for UIC
+ * @irq: the interrupt number
+ * @desc: the interrupt description structure for this irq
+ *
+ * This is modified version of the generic handle_level_irq() suitable
+ * for the UIC. On the UIC, acking (i.e. clearing the SR bit) a level
+ * irq will have no effect if the interrupt is still asserted by the
+ * device, even if the interrupt is already masked. Therefore, unlike
+ * the standard handle_level_irq(), we must ack the interrupt *after*
+ * invoking the ISR (which should have de-asserted the interrupt in
+ * the external source). For edge interrupts we ack at the beginning
+ * instead of the end, to keep the window in which we can miss an
+ * interrupt as small as possible.
+ */
+void fastcall handle_uic_irq(unsigned int irq, struct irq_desc *desc)
+{
+ unsigned int cpu = smp_processor_id();
+ struct irqaction *action;
+ irqreturn_t action_ret;
+
+ spin_lock(&desc->lock);
+ if (desc->status & IRQ_LEVEL)
+ desc->chip->mask(irq);
+ else
+ desc->chip->mask_ack(irq);
+
+ if (unlikely(desc->status & IRQ_INPROGRESS))
+ goto out_unlock;
+ desc->status &= ~(IRQ_REPLAY | IRQ_WAITING);
+ kstat_cpu(cpu).irqs[irq]++;
+
+ /*
+ * If its disabled or no action available
+ * keep it masked and get out of here
+ */
+ action = desc->action;
+ if (unlikely(!action || (desc->status & IRQ_DISABLED))) {
+ desc->status |= IRQ_PENDING;
+ goto out_unlock;
+ }
+
+ desc->status |= IRQ_INPROGRESS;
+ desc->status &= ~IRQ_PENDING;
+ spin_unlock(&desc->lock);
+
+ action_ret = handle_IRQ_event(irq, action);
+
+ spin_lock(&desc->lock);
+ desc->status &= ~IRQ_INPROGRESS;
+ if (desc->status & IRQ_LEVEL)
+ desc->chip->ack(irq);
+ if (!(desc->status & IRQ_DISABLED) && desc->chip->unmask)
+ desc->chip->unmask(irq);
+out_unlock:
+ spin_unlock(&desc->lock);
+}
+