ARM: 7177/1: GIC: avoid skipping non-existent PPIs in irq_start calculation

Commit 4294f8baa ("ARM: gic: add irq_domain support") defines irq_start
as irq_start = (irq_start & ~31) + 16; On a platform with a GIC and a
CPU without PPIs, this results in irq_start being off by 16.

This patch fixes gic_init so that we only carve out a PPI space when
PPIs exist for the GIC being initialised.

Cc: Rob Herring <rob.herring@calxeda.com>
Signed-off-by: Will Deacon <will.deacon@arm.com>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>

1 files changed, 8 insertions, 5 deletions

diff --git a/arch/arm/common/gic.c b/arch/arm/common/gic.c
index 43240f315dea..410a546060a2 100644
--- a/arch/arm/common/gic.c
+++ b/arch/arm/common/gic.c
@@ -582,13 +582,16 @@ void __init gic_init(unsigned int gic_nr, int irq_start,
          * For primary GICs, skip over SGIs.
          * For secondary GICs, skip over PPIs, too.
          */
+        domain->hwirq_base = 32;
         if (gic_nr == 0) {
                 gic_cpu_base_addr = cpu_base;
-                domain->hwirq_base = 16;
-                if (irq_start > 0)
-                        irq_start = (irq_start & ~31) + 16;
-        } else
-                domain->hwirq_base = 32;
+
+                if ((irq_start & 31) > 0) {
+                        domain->hwirq_base = 16;
+                        if (irq_start != -1)
+                                irq_start = (irq_start & ~31) + 16;
+                }
+        }
 
         /*
          * Find out how many interrupts are supported.