v4.19.13 snapshot.
diff --git a/arch/mips/sgi-ip27/ip27-irqno.c b/arch/mips/sgi-ip27/ip27-irqno.c
new file mode 100644
index 0000000..957ab58
--- /dev/null
+++ b/arch/mips/sgi-ip27/ip27-irqno.c
@@ -0,0 +1,48 @@
+/*
+ * This file is subject to the terms and conditions of the GNU General Public
+ * License. See the file "COPYING" in the main directory of this archive
+ * for more details.
+ */
+#include <linux/init.h>
+#include <linux/irq.h>
+#include <linux/types.h>
+
+#include <asm/barrier.h>
+
+static DECLARE_BITMAP(irq_map, NR_IRQS);
+
+int allocate_irqno(void)
+{
+ int irq;
+
+again:
+ irq = find_first_zero_bit(irq_map, NR_IRQS);
+
+ if (irq >= NR_IRQS)
+ return -ENOSPC;
+
+ if (test_and_set_bit(irq, irq_map))
+ goto again;
+
+ return irq;
+}
+
+/*
+ * Allocate the 16 legacy interrupts for i8259 devices. This happens early
+ * in the kernel initialization so treating allocation failure as BUG() is
+ * ok.
+ */
+void __init alloc_legacy_irqno(void)
+{
+ int i;
+
+ for (i = 0; i <= 16; i++)
+ BUG_ON(test_and_set_bit(i, irq_map));
+}
+
+void free_irqno(unsigned int irq)
+{
+ smp_mb__before_atomic();
+ clear_bit(irq, irq_map);
+ smp_mb__after_atomic();
+}