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/arch/powerpc/platforms/iseries/setup.c b/arch/powerpc/platforms/iseries/setup.c
index 6ce8a404ba6b..a6fd9bedb074 100644
--- a/arch/powerpc/platforms/iseries/setup.c
+++ b/arch/powerpc/platforms/iseries/setup.c
@@ -54,6 +54,7 @@
 #include <asm/iseries/hv_lp_event.h>
 #include <asm/iseries/lpar_map.h>
 #include <asm/udbg.h>
+#include <asm/irq.h>
 
 #include "naca.h"
 #include "setup.h"
@@ -684,6 +685,12 @@ static int __init iseries_probe(void)
         powerpc_firmware_features |= FW_FEATURE_ISERIES;
         powerpc_firmware_features |= FW_FEATURE_LPAR;
 
+        /*
+         * The Hypervisor only allows us up to 256 interrupt
+         * sources (the irq number is passed in a u8).
+         */
+        virt_irq_max = 255;
+
         return 1;
 }