[PATCH 3/3] irq/irq_sim: implement irq_sim_irq2offset()

[Bartosz Golaszewski <brgl@bgdev.pl>]

Add a routine allowing to retrieve the offset corresponding with an
allocated interrupt number from an irq_sim object.

Signed-off-by: Bartosz Golaszewski <brgl@bgdev.pl>
---
 include/linux/irq_sim.h |  1 +
 kernel/irq/irq_sim.c    | 15 +++++++++++++++
 2 files changed, 16 insertions(+)

diff --git a/include/linux/irq_sim.h b/include/linux/irq_sim.h
index 246f593face8..e9768ca81e3e 100644
--- a/include/linux/irq_sim.h
+++ b/include/linux/irq_sim.h
@@ -41,5 +41,6 @@ void irq_sim_fini(struct irq_sim *sim);
 void irq_sim_fire(struct irq_sim *sim, unsigned int offset);
 int irq_sim_irqnum(struct irq_sim *sim, unsigned int offset);
 int irq_sim_baseirq(struct irq_sim *sim);
+unsigned int irq_sim_irq2offset(struct irq_sim *sim, int irq);
 
 #endif /* _LINUX_IRQ_SIM_H */
diff --git a/kernel/irq/irq_sim.c b/kernel/irq/irq_sim.c
index 1be10d0e295f..9a9a1bc8853c 100644
--- a/kernel/irq/irq_sim.c
+++ b/kernel/irq/irq_sim.c
@@ -174,3 +174,18 @@ int irq_sim_baseirq(struct irq_sim *sim)
 	return irq_sim_irqnum(sim, 0);
 }
 EXPORT_SYMBOL_GPL(irq_sim_baseirq);
+
+/**
+ * irq_sim_irq2offset - Get the offset of an allocated interrupt.
+ *
+ * @sim:        The interrupt simulator object.
+ * irq:         Allocated interrupt number.
+ *
+ * Perform a reverse lookup for the interrupt number and return its offset in
+ * the array allocated by sim_irq.
+ */
+unsigned int irq_sim_irq2offset(struct irq_sim *sim, int irq)
+{
+	return irq - sim->irq_base;
+}
+EXPORT_SYMBOL_GPL(irq_sim_irq2offset);
-- 
2.13.2