genirq: Implement irq reservation
Mark a range of interrupts as allocated. In the SPARSE_IRQ=n case we
need this to update the bitmap for the legacy irqs so the enumerator
via irq_get_next_irq() works.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
diff --git a/kernel/irq/irqdesc.c b/kernel/irq/irqdesc.c
index 2e7e94e..35d9052 100644
--- a/kernel/irq/irqdesc.c
+++ b/kernel/irq/irqdesc.c
@@ -464,6 +464,32 @@
}
/**
+ * irq_reserve_irqs - mark irqs allocated
+ * @from: mark from irq number
+ * @cnt: number of irqs to mark
+ *
+ * Returns 0 on success or an appropriate error code
+ */
+int irq_reserve_irqs(unsigned int from, unsigned int cnt)
+{
+ unsigned long flags;
+ unsigned int start;
+ int ret = 0;
+
+ if (!cnt || (from + cnt) > nr_irqs)
+ return -EINVAL;
+
+ raw_spin_lock_irqsave(&sparse_irq_lock, flags);
+ start = bitmap_find_next_zero_area(allocated_irqs, nr_irqs, from, cnt, 0);
+ if (start == from)
+ bitmap_set(allocated_irqs, start, cnt);
+ else
+ ret = -EEXIST;
+ raw_spin_unlock_irqrestore(&sparse_irq_lock, flags);
+ return ret;
+}
+
+/**
* irq_get_next_irq - get next allocated irq number
* @offset: where to start the search
*