powerpc: iSeries has only 256 IRQs

The iSeries Hypervisor only allows us to specify IRQ numbers up to 255 (it
has a u8 field to pass it in).  This patch allows platforms to specify a
maximum to the virtual IRQ numbers we will use and has iSeries set that
to 255.  If not set, the maximum is NR_IRQS - 1 (as before).

Signed-off-by: Stephen Rothwell <sfr@canb.auug.org.au>

1 files changed, 7 insertions, 0 deletions

diff --git a/include/asm-powerpc/irq.h b/include/asm-powerpc/irq.h
index 51f87d9993b6..7bc6d73b2823 100644
--- a/include/asm-powerpc/irq.h
+++ b/include/asm-powerpc/irq.h
@@ -54,6 +54,13 @@
  */
 extern unsigned int virt_irq_to_real_map[NR_IRQS];
 
+/* The maximum virtual IRQ number that we support.  This
+ * can be set by the platform and will be reduced by the
+ * value of __irq_offset_value.  It defaults to and is
+ * capped by (NR_IRQS - 1).
+ */
+extern unsigned int virt_irq_max;
+
 /* Create a mapping for a real_irq if it doesn't already exist.
  * Return the virtual irq as a convenience.
  */