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/include/linux/irq.h b/include/linux/irq.h
index cefacf9..096b74d 100644 (file)
--- a/include/linux/irq.h
+++ b/include/linux/irq.h
@@ -400,6 +400,7 @@ static inline struct irq_2_iommu *irq_data_get_iommu(struct irq_data *d)
 
 int irq_alloc_descs(int irq, unsigned int from, unsigned int cnt, int node);
 void irq_free_descs(unsigned int irq, unsigned int cnt);
+int irq_reserve_irqs(unsigned int from, unsigned int cnt);
 
 static inline int irq_alloc_desc(int node)
 {

diff --git a/kernel/irq/irqdesc.c b/kernel/irq/irqdesc.c
index 2e7e94e..35d9052 100644 (file)
--- a/kernel/irq/irqdesc.c
+++ b/kernel/irq/irqdesc.c
@@ -463,6 +463,32 @@ err:
        return ret;
 }
 
+/**
+ * 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