x86, acpi/irq: Handle isa irqs that are not identity mapped to gsi's.

ACPI irq source overrides are allowed for the 16 isa irqs and are
allowed to map any gsi to any isa irq.  A few motherboards have been
seen to take advantage of this and put the isa irqs on the 2nd or
3rd ioapic.  This causes some problems, most notably the fact
that we can not use any gsi < 16.

To correct this move the gsis that are not isa irqs and have
a gsi number < 16 into the linux irq space just past gsi_end.
This is what the es7000 platform is doing today.  Moving only the
low 16 gsis above the rest of the gsi's only penalizes weird
platforms, leaving sane acpi implementations with a 1-1 mapping
of gsis and irqs.

Signed-off-by: Eric W. Biederman <ebiederm@xmission.com>
LKML-Reference: <1269936436-7039-14-git-send-email-ebiederm@xmission.com>
Signed-off-by: H. Peter Anvin <hpa@zytor.com>

1 files changed, 6 insertions, 2 deletions

diff --git a/arch/x86/kernel/apic/io_apic.c b/arch/x86/kernel/apic/io_apic.c
index 9f3f6ca86dac..594827c3c615 100644
--- a/arch/x86/kernel/apic/io_apic.c
+++ b/arch/x86/kernel/apic/io_apic.c
@@ -1037,7 +1037,11 @@ static int pin_2_irq(int idx, int apic, int pin)
                  */
                 if (ioapic_renumber_irq)
                         gsi = ioapic_renumber_irq(apic, gsi);
-                irq = gsi;
+
+                if (gsi >= NR_IRQS_LEGACY)
+                        irq = gsi;
+                else
+                        irq = gsi_end + 1 + gsi;
         }
 
 #ifdef CONFIG_X86_32
@@ -3852,7 +3856,7 @@ void __init probe_nr_irqs_gsi(void)
 {
         int nr;
 
-        nr = gsi_end + 1;
+        nr = gsi_end + 1 + NR_IRQS_LEGACY;
         if (nr > nr_irqs_gsi)
                 nr_irqs_gsi = nr;